Bjarne Rud

• Lund-Hansen, Magne; Gløersen, Øyvind; Rud, Bjarne & Losnegard, Thomas Johansen (2023). What is the optimal classical style sub-technique during uphill roller skiing in elite male cross-country skiers? European Journal of Applied Physiology. ISSN 1439-6319. 123, s. 2833–2842. doi: 10.1007/s00421-023-05261-w. Fulltekst i vitenarkiv
• Dahl, Even B.; Øygard, Eivind; Paulsen, Gøran; Rud, Bjarne & Losnegard, Thomas Johansen (2021). Morning Preconditioning Exercise Does Not Increase Afternoon Performance in Competitive Runners. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 16(12), s. 1816–1823. doi: 10.1123/ijspp.2020-0747. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: Preconditioning exercise is a widely used strategy believed to enhance performance later the same day. The authors examined the influence of preconditioning exercises 6 hours prior to a time-to-exhaustion (TTE) test during treadmill running. Methods: Ten male competitive runners (age = 26 [3] y, height = 184 [8] cm, weight = 73 [9] kg, maximum oxygen consumption = 72 [7] mL·kg−1·min−1) did a preconditioning session of running (RUN) or resistance exercise (RES) or no morning exercise (NoEx) in a randomized order, separated by >72 hours. The RUN consisted of 15 minutes of low-intensity running and 4 × 15 seconds at race pace (21–24 km·h−1) on a treadmill; RES involved 5 minutes of low-intensity running and 2 × 3 repetitions of isokinetic 1-leg shallow squats with maximal mobilization. Following a 6-hour break, electrically evoked force (m. vastus medialis), countermovement jump, running economy, and a TTE of approximately 2 minutes were examined. Results: Relative to NoEx, no difference was seen for RUN or RES in TTE (mean ± 95% CI: −1.3% ± 3.4% and −0.5% ± 6.0%) or running economy (0.2% ± 1.6% and 1.9% ± 2.7%; all Ps > .05). Jump height was not different for the RUN condition (1.0% ± 2.7%]) but tended to be higher in RES than in the NoEx condition (1.5% ± 1.6%, P = .07). The electrically evoked force tended to reveal low-frequency fatigue (reduced 20:50-Hz peak force ratio) only after RES compared to NoEx (−4.5% ± 4.6%, P = .06). Conclusion: The RUN or RES 6 hours prior to approximately 2 minutes of TTE running test did not improve performance in competitive runners.

• Rud, Bjarne; Øygard, Eivind; Dahl, Even B.; Paulsen, Gøran & Losnegard, Thomas Johansen (2021). The Effect of Resistance Exercise Priming in the Morning on Afternoon Sprint Cross-Country Skiing Performance. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 16(12), s. 1786–1793. doi: 10.1123/ijspp.2020-0881. Vis sammendrag

  Purpose: We tested whether a single session of heavy-load resistance priming conducted in the morning improved double-poling (DP) performance in the afternoon. Methods: Eight national-level male cross-country skiers (mean [SD]: 23 [3] y, 184 [6] cm, 73 [7] kg, maximum oxygen consumption = 69 [6] mL·kg−1·min−1) carried out 2 days of afternoon performance tests. In the morning, 5 hours before tests, subjects were counterbalanced to either a session of 3 × 3 repetitions (approximately 85%–90% 1-repetition maximum) of squat and sitting pullover exercises or no exercise. The performance was evaluated in DP as time to exhaustion (TTE) (approximately 3 min) on a treadmill and 30-m indoor sprints before and after TTE (30-m DP pre/post). Furthermore, submaximal DP oxygen cost, countermovement jump, and isometric knee-extension force during electrical stimulation were conducted. Participants reported perceived readiness on test days. Results: Resistance exercise session versus no exercise did not differ for TTE (approximately 3 min above) (mean ± 95% confidence interval = 3.6% ± 6.0%; P = .29; effect size [ES], Cohen d = 0.27), 30-m DP pre (−0.56% ± 0.80%; P = .21; ES = 0.20), 30-m DP post (−0.18% ± 1.13%; P = .76; ES = 0.03), countermovement jump (−2.0% ± 2.8%; P = .21; ES = 0.12), DP oxygen cost (−0.13% ± 2.04%; P = .91; ES = 0.02), or perceived readiness (P ≥ .11). Electrical stimulation force was not different in contraction or relaxation time but revealed low-frequency fatigue in the afternoon for the resistance exercise session only (−12% [7%]; P = .01; ES = 1.3). Conclusion: A single session of heavy-load, low-volume resistance exercise in the morning did not increase afternoon DP performance of short duration in high-level skiers. However, leg low-frequency fatigue after resistance priming, together with the presence of small positive effects in 2 out of 3 DP tests, may indicate that the preconditioning was too strenuous.

• Trøen, Erik; Rud, Bjarne; Karlsson, Øyvind; Carlsen, Camilla Høivik; Gilgien, Matthias & Paulsen, Gøran [Vis alle 8 forfattere av denne artikkelen] (2020). Pole Length’s Influence on Performance During Classic-Style Snow Skiing in Well-Trained Cross-Country Skiers. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 15(6), s. 884–891. doi: 10.1123/ijspp.2019-0310. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: To investigate how self-selected pole length (PL) of ∼84% (PL84%) compared with ∼90% (PL90%) of body height influenced performance during a 700-m time trial with undulating terrain on snow. Methods: Twenty-one cross-country skiers, 7 of whom were women, performed 4 trials at a maximal effort in a counterbalanced fashion with PL84% and PL90% separated by 20-minute breaks between trials. In trials I and II, only double poling was allowed, while in trials III and IV, skiers used self-selected classical subtechniques. Continuous speed, cyclic parameters, and heart rate were collected using microsensors in addition to a post-time-trial rating of perceived exertion (RPE). Results: The 700-m times with only double poling were significantly shorter with PL90% than PL84% (mean ± 95% confidence limits –1.6% ± 1.0%). Segment analyses showed higher speed with PL90% in uphill sections than with PL84% (3.7% ± 2.1%), with the greatest difference found for the female skiers (5.6% ± 2.9%). In contrast, on flat terrain at high skiing speeds, speed was reduced with PL90% compared with PL84% (–1.5% ± 1.4%); this was only significant for the male skiers. During free choice of classical subtechniques, PL did not influence performance in any segments, choice of subtechnique, or cycle rate during the trials. No differences in rating of perceived exertion or heart rate between PLs were found. Conclusions: PL90% improved performance in uphills at low speeds when using double poling but hindered performance on flat terrain and at higher speeds compared with self-selected PLs. Choice of PL should, therefore, be based on racecourse topography, preferred subtechniques, and the skier’s physiological and technical abilities.

• Skattebo, Øyvind; Calbet, Jose Antonio Lopez; Rud, Bjarne; Capelli, Carlo & Hallén, Jostein (2020). Contribution of oxygen extraction fraction to maximal oxygen uptake in healthy young men. Acta Physiologica. ISSN 1748-1708. 230(2). doi: 10.1111/apha.13486. Fulltekst i vitenarkiv Vis sammendrag

  We analysed the importance of systemic and peripheral arteriovenous O2 difference ( urn:x-wiley:17481708:media:apha13486:apha13486-math-0001 difference and a‐vfO2 difference, respectively) and O2 extraction fraction for maximal oxygen uptake ( urn:x-wiley:17481708:media:apha13486:apha13486-math-0002). Fick law of diffusion and the Piiper and Scheid model were applied to investigate whether diffusion versus perfusion limitations vary with urn:x-wiley:17481708:media:apha13486:apha13486-math-0003. Articles (n = 17) publishing individual data (n = 154) on urn:x-wiley:17481708:media:apha13486:apha13486-math-0004, maximal cardiac output ( urn:x-wiley:17481708:media:apha13486:apha13486-math-0005; indicator‐dilution or the Fick method), urn:x-wiley:17481708:media:apha13486:apha13486-math-0006 difference (catheters or the Fick equation) and systemic O2 extraction fraction were identified. For the peripheral responses, group‐mean data (articles: n = 27; subjects: n = 234) on leg blood flow (LBF; thermodilution), a‐vfO2 difference and O2 extraction fraction (arterial and femoral venous catheters) were obtained. urn:x-wiley:17481708:media:apha13486:apha13486-math-0007 and two‐LBF increased linearly by 4.9‐6.0 L · min–1 per 1 L · min–1 increase in urn:x-wiley:17481708:media:apha13486:apha13486-math-0008 (R2 = .73 and R2 = .67, respectively; both P < .001). The urn:x-wiley:17481708:media:apha13486:apha13486-math-0009 difference increased from 118‐168 mL · L–1 from a urn:x-wiley:17481708:media:apha13486:apha13486-math-0010 of 2‐4.5 L · min–1 followed by a reduction (second‐order polynomial: R2 = .27). After accounting for a hypoxemia‐induced decrease in arterial O2 content with increasing urn:x-wiley:17481708:media:apha13486:apha13486-math-0011 (R2 = .17; P < .001), systemic O2 extraction fraction increased up to ~90% ( urn:x-wiley:17481708:media:apha13486:apha13486-math-0012: 4.5 L · min–1) with no further change (exponential decay model: R2 = .42). Likewise, leg O2 extraction fraction increased with urn:x-wiley:17481708:media:apha13486:apha13486-math-0013 to approach a maximal value of ~90‐95% (R2 = .83). Muscle O2 diffusing capacity and the equilibration index Y increased linearly with urn:x-wiley:17481708:media:apha13486:apha13486-math-0014 (R2 = .77 and R2 = .31, respectively; both P < .01), reflecting decreasing O2 diffusional limitations and accentuating O2 delivery limitations. In conclusion, although O2 delivery is the main limiting factor to urn:x-wiley:17481708:media:apha13486:apha13486-math-0015, enhanced O2 extraction fraction (≥90%) contributes to the remarkably high urn:x-wiley:17481708:media:apha13486:apha13486-math-0016 in endurance‐trained individuals.

• Skattebo, Øyvind; Capelli, Carlo; Rud, Bjarne; Auensen, Marius; Calbet, Jose Antonio Lopez & Hallén, Jostein (2020). Increased oxygen extraction and mitochondrial protein expression after small muscle mass endurance training. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 30(9), s. 1615–1631. doi: 10.1111/sms.13707. Vis sammendrag

  When exercising with a small muscle mass, the mass‐specific O2 delivery exceeds the muscle oxidative capacity resulting in a lower O2 extraction compared with whole‐body exercise. We elevated the muscle oxidative capacity and tested its impact on O2 extraction during small muscle mass exercise. Nine individuals conducted six weeks of one‐legged knee extension (1L‐KE) endurance training. After training, the trained leg (TL) displayed 45% higher citrate synthase and COX‐IV protein content in vastus lateralis and 15%‐22% higher pulmonary oxygen uptake ( urn:x-wiley:09057188:media:sms13707:sms13707-math-0001) and peak power output ( urn:x-wiley:09057188:media:sms13707:sms13707-math-0002) during 1L‐KE than the control leg (CON; all P < .05). Leg O2 extraction (catheters) and blood flow (ultrasound Doppler) were measured while both legs exercised simultaneously during 2L‐KE at the same submaximal power outputs (real‐time feedback‐controlled). TL displayed higher O2 extraction than CON (main effect: 1.7 ± 1.6% points; P = .010; 40%‐83% of urn:x-wiley:09057188:media:sms13707:sms13707-math-0003) with the largest between‐leg difference at 83% of urn:x-wiley:09057188:media:sms13707:sms13707-math-0004 (O2 extraction: 3.2 ± 2.2% points; arteriovenous O2 difference: 7.1 ± 4.8 mL· L−1; P < .001). At 83% of urn:x-wiley:09057188:media:sms13707:sms13707-math-0005, muscle O2 conductance (DMO2; Fick law of diffusion) and the equilibration index Y were higher in TL (P < .01), indicating reduced diffusion limitations. The between‐leg difference in O2 extraction correlated with the between‐leg ratio of citrate synthase and COX‐IV (r = .72‐.73; P = .03), but not with the difference in the capillary‐to‐fiber ratio (P = .965). In conclusion, endurance training improves O2 extraction during small muscle mass exercise by elevating the muscle oxidative capacity and the recruitment of DMO2, especially evident during high‐intensity exercise exploiting a larger fraction of the muscle oxidative capacity.

• Mølmen, Knut Sindre; Hallén, Jostein & Rud, Bjarne (2019). Peripheral adaptations to endurance training - Effect of active muscle mass. Translational Sports Medicine (TSM). ISSN 2573-8488. 2(5), s. 240–247. doi: 10.1002/tsm2.87. Fulltekst i vitenarkiv Vis sammendrag

  The purpose of this study was to evaluate whether adaptations to endurance training are affected by active muscle mass during training. Eleven healthy subjects performed 5 weeks of one‐legged knee extension (1‐KE) training with both legs, separately. During the 1‐KE workouts for one of the legs, arm cycling was added (1L2A), while the other leg only performed 1‐KE (1L). During the training sessions, the 1‐KE power output and session duration were equal for both legs. Whole‐body oxygen uptake (V̇O2), adrenaline, and noradrenaline plasma concentrations were 112% ± 11%, 139% ± 144%, and 197% ± 101% higher during 1L2A than 1L, respectively. However, this did not affect the 1‐KE training adaptations since submaximal O2‐cost, heart rate and blood lactate concentration, maximal V̇O2, and power output all improved equally in both legs. This was supported by similar capillarization and concentration of oxidative enzymes in the legs after the training period. The present study therefore indicates that the size of active muscle mass per se during exercise does not affect adaptations to endurance training.

• Losnegard, Thomas Johansen; Tosterud, Ola Kristoffer; Trøen, Erik; Carlsen, Camilla Høivik; Paulsen, Gøran & Rud, Bjarne (2019). The influence of pole lengths on O2-cost, kinematics, and performance in double poling at high speeds before and after a training period with long poles. European Journal of Applied Physiology. ISSN 1439-6319. 119(11-12), s. 2579–2587. doi: 10.1007/s00421-019-04237-z. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: Previous studies have found an acute performance improvement with longer pole lengths in double poling (DP) at low-to-moderate speeds. We investigated the influence of pole lengths (PL) on O2-cost, 3D kinematics, and performance in DP at moderate-to-high speeds before (Pre) and after (Post) eight training sessions with long poles on a rollerski treadmill. Methods: Seven male and four female skiers completed tests with two different PLs (84 and 90% of body height). Submaximal O2-cost (1º; 4.5 [females] or 6 m s−1 [males]) and a peak velocity test (1º; ∼  7.3 m s−1) were assessed before and after a six week training period. The training sessions consisted of 50 min of low-moderate intensity training and 4 × 10 s maximal sprints with PL90%. Results: On average for all tests, PL84% induced 1.0 ± 1.0% higher peak velocity compared to PL90% (mean ± CI) with no difference in vertical displacement of center of mass (COMz). From Pre to Post, peak velocity and cycle time were increased and the displacement of COMz were reduced similarly for both PLs. At moderate speed, PL90% induced less displacement of COMz with subsequent 1.1 ± 0.7% lower O2-cost compared to PL84%. From Pre to Post, the O2-cost and COMz were reduced similarly for both PLs. Conclusions: Longer PL than skiers self-selected lengths reduce O2-cost at moderate speeds, but induced lower peak velocity. Eight sessions of training with PL90% did not influence the difference between PL84% and PL90% on O2-cost, kinematics or peak velocity.

• Karlsson, Øyvind; Gilgien, Matthias; Gløersen, Øyvind Nøstdahl; Rud, Bjarne & Losnegard, Thomas Johansen (2018). Exercise intensity during cross-country skiing described by oxygen demands in flat and uphill terrain. Frontiers in Physiology. ISSN 1664-042X. 9, s. 1–12. doi: 10.3389/fphys.2018.00846. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: In this study wearable global navigation satellite system units were used on athletes to investigate pacing patterns by describing exercise intensities in flat and uphill terrain during a simulated cross-country ski race. Methods: Eight well-trained male skiers (age: 23.0 ± 4.8 years, height: 183.8 ± 6.8 cm, weight: 77.1 ± 6.1 kg, VO2peak: 73 ± 5 mL⋅kg-1⋅min-1) completed a 13.5-km individual time trial outdoors and a standardized indoor treadmill protocol on roller skis. Positional data were recorded during the time trial using a differential global navigation satellite system to calculate external workloads in flat and uphill terrain. From treadmill tests, the individual relationships between oxygen consumption and external workload in flat (1°) and uphill (8°) terrain were determined, in addition to VO2peak and the maximal accumulated O2-deficit. To estimate the exercise intensity in the time trial, the O2-demand in two different flat and five different uphill sections was calculated by extrapolation of individual O2-consumption/workload ratios. Results: There was a significant interaction between section and average O2-demands, with higher O2-demands in the uphill sections (110–160% of VO2peak) than in the flat sections (≤100% of VO2peak) (p < 0.01). The maximal accumulated O2-deficit associated with uphill treadmill roller skiing was significantly higher compared to flat (6.2 ± 0.5 vs. 4.6 ± 0.5 L, p < 0.01), while no significant difference was found in VO2peak. Conclusion: Cross-country (XC) skiers repeatedly applied exercise intensities exceeding their maximal aerobic power. ΣO2-deficits were higher during uphill skiing compared to flat which has implications for the duration and magnitude of supramaximal work rates that can be applied in different types of terrain.

• Carlsen, Camilla Høivik; Rud, Bjarne; Myklebust, Håvard & Losnegard, Thomas Johansen (2017). Pole lengths influence O2-cost during double poling in highly trained cross-country skiers. European Journal of Applied Physiology. ISSN 1439-6319. 118(2), s. 271–281. doi: 10.1007/s00421-017-3767-x. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: In elite cross-country skiing, double poling is used in different terrain. This study compared O2-cost and kinematics during double poling with four different pole lengths [self-selected (SS), SS − 5 cm, SS + 5 cm, SS + 10 cm] at Low versus Moderate incline. Methods: Thirteen highly trained male cross-country skiers (mean ± SD 23 ± 3 years; 182 ± 4 cm; 77 ± 6 kg) completed eight submaximal trials with roller skis on a treadmill at two conditions: “Low incline” (1.7°; 4.5 m s−1) and “Moderate incline” (4.5°; 2.5 m s−1) with each of the four pole lengths. O2-cost and 3D body kinematics were assessed in each trial. Results: In Low incline, SS + 10 cm induced a lower O2-cost than all the other pole lengths [P < 0.05; effect size (ES) 0.5–0.8], whereas no differences were found between the remaining pole lengths (P > 0.05; ES 0.2–0.4). In Moderate incline, significant differences between all pole lengths were found for O2-cost, with SS − 5 cm > SS > SS + 5 cm > SS + 10 cm (P < 0.05; ES 0.6–1.8). The relative differences in O2-cost between SS and the other pole lengths were greater in Moderate incline than Low incline (SS − 5 cm; 1.5%, ES 0.8, SS + 5 cm; 1.3%, ES 1.0, and SS + 10 cm; 1.9%, ES 1.0, all P < 0.05). No difference was found in cycle, poling or reposition times between pole lengths. However, at both conditions a smaller total vertical displacement of center of mass was observed with SS + 10 cm compared to the other pole lengths. Conclusion: Increasing pole length from SS − 5 cm to SS + 10 cm during double poling induced lower O2-cost and this advantage was greater in Moderate compared to Low incline.

• Børve, Jørgen; Jevne, Steffen N.; Rud, Bjarne & Losnegard, Thomas Johansen (2017). Upper-Body Muscular Endurance Training Improves Performance Following 50 min of Double Poling in Well-Trained Cross-Country Skiers. Frontiers in Physiology. ISSN 1664-042X. 8(690). doi: 10.3389/fphys.2017.00690. Fulltekst i vitenarkiv Vis sammendrag

  This study investigated the effect of muscular endurance training on O2-cost and performance in double poling (DP) on a rollerski treadmill. Twenty-two well-trained cross-country skiers (31 ± 4 years, 77 ± 9 kg, 181 ± 8 cm, VO2max running: 64 ± 5 mL·kg−1·min−1) were counter-balanced to either a combined muscular endurance and running interval training group [MET; n = 11 (♂ = 9, ♀ = 2)], or an endurance running interval training group [ET; n = 11 (♂ = 9, ♀ = 2)]. Both groups continued their normal low-and moderate intensity training, but replaced 2 weekly high intensity-training sessions with two project-specific sessions for 6 weeks. In these sessions, MET combined upper-body muscular endurance training (4 × 30 repetitions, 90 s rest between sets) and running intervals (3 × 4 or 2 × 6 min, 3 min rest), while ET performed running intervals only (6 × 4 or 4 × 6 min, 3 min rest). The DP test-protocol consisted of 50 min submaximal poling for O2-cost measurement, followed by a self-paced 1,000-m performance test. In addition, subjects performed a VO2max test in running. MET increased muscular endurance (P < 0.05) and 1RM in simulated DP (P < 0.01) more than ET. Further, MET reduced the 1,000-m time and O2-cost compared to baseline values (P < 0.05), and tended to improve the 1,000-m time more than ET (P = 0.06). There were no changes in VO2max running or VO2peak DP in either MET or ET. In conclusion, 6 weeks of muscular endurance training increased both muscular endurance and 1RM in simulated DP. Further, specific upper-body muscular endurance training improved DP performance and thus, seems as a promising training model to optimize performance in well-trained cross-country skiers.

• Rud, Bjarne; Secher, Niels H; Nilsson, Johnny Erik; Smith, Gerald & Hallén, Jostein (2014). Metabolic and mechanical involvement of arms and legs in simulated double pole skiing. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 24(6), s. 913–919. doi: 10.1111/sms.12133.
• Slettaløkken, Gunnar; Rehn, Tommy Aune; Munkvik, Morten; Rud, Bjarne; Nymark, Bernt Sivert & Lunde, Per Kristian [Vis alle 9 forfattere av denne artikkelen] (2013). Normal training response in skeletal muscle of post-infarction heart failure patients. European Journal of Sport Science (EJSS). ISSN 1746-1391. 13(2), s. 231–239. doi: 10.1080/17461391.2011.624197. Vis sammendrag

  Congestive heart failure (CHF) patients experience reduced muscle fatigue resistance and exercise capacity. The aim of this study was to assess whether skeletal muscle in CHF patients has a normal training response compared to healthy subjects. We compared the effect of one-legged knee extensor (1-KE) endurance training in CHF patients (n=10), patients with coronary artery disease (CAD, n=9) and healthy subjects (n=13). The training response was evaluated by comparing trained leg and control leg after the training period. The fall in peak torque during 75 maximal 1-KE isokinetic contractions revealed that CHF patients were less fatigue resistant than healthy subjects in the control leg, but not in the trained leg. Peak power and peak oxygen uptake during dynamic 1-KE exercise was ~10–16% higher in trained leg than control leg. This training response was not significant different between groups. Muscle biopsies of vastus lateralis showed that fibre type composition was not different between trained leg and control leg. Capillary density was 6.5% higher in trained leg than control leg when all groups were pooled. In conclusion, the more fatigable skeletal muscle of CHF patients responds equally to endurance training compared to skeletal muscle of CAD patients and healthy subjects.

• Rud, Bjarne; Foss, Øivind; Krustrup, Peter; Secher, Niels H & Hallén, Jostein (2012). One-legged endurance training: leg blood flow and oxygen extraction during cycling exercise. Acta Physiologica. ISSN 1748-1708. 205(1), s. 177–185. doi: 10.1111/j.1748-1716.2011.02383.x. Vis sammendrag

  Aim:  As a consequence of enhanced local vascular conductance, perfusion of muscles increases with exercise intensity to suffice the oxygen demand. However, when maximal oxygen uptake (VO2max) and cardiac output are approached, the increase in conductance is blunted. Endurance training increases muscle metabolic capacity, but to what extent that affects the regulation of muscle vascular conductance during exercise is unknown. Methods:  Seven weeks of one-legged endurance training was carried out by twelve subjects. Pulmonary VO2 during cycling and one-legged cycling was tested before and after training, while VO2 of the trained leg (TL) and control leg (CL) during cycling was determined after training. Results: VO2max for cycling was unaffected by training, although one-legged VO2max became 6.7 (2.3)% (mean ± SE) larger with TL than with CL. Also TL citrate synthase activity was higher [30 (12)%; P < 0.05]. With the two legs working at precisely the same power during cycling at high intensity (n = 8), leg oxygen uptake was 21 (8)% larger for TL than for CL (P < 0.05) with oxygen extraction being 3.5 (1.1)% higher (P < 0.05) and leg blood flow tended to be higher by 16.0 (7.0)% (P = 0.06). Conclusion:  That enhanced VO2max for the trained leg had no implication for cycling VO2max supports that there is a central limitation to VO2max during whole-body exercise. However, the metabolic balance between the legs was changed during high-intensity exercise as oxygen delivery and oxygen extraction were higher in the trained leg, suggesting that endurance training ameliorates blunting of leg blood flow and oxygen uptake during whole-body exercise.

• Slettaløkken, Gunnar; Rehn, Tommy Aune; Munkvik, Morten; Rud, Bjarne; SØKJER-PETERSEN, MARTIN & Lunde, Per Kristian [Vis alle 9 forfattere av denne artikkelen] (2012). Preserved metabolic reserve capacity in skeletal muscle of post-infarction heart failure patients. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 22(2), s. 199–206. doi: 10.1111/j.1600-0838.2010.01226.x. Vis sammendrag

  It has been proposed that exercise capacity during whole body exercise in post-infarction congestive heart failure (CHF) patients is limited by skeletal muscle function. We therefore investigated the balance between cardiopulmonary and muscular metabolic capacity. CHF patients (n58) and healthy subjects (HS, n512) were included. Patients with coronary artery disease (CAD, n58) were included as a control for medication. All subjects performed a stepwise incremental load test during bicycling ( 24 kg muscle mass), two-legged knee extensor (2-KE) exercise ( 4 kg muscle mass) and onelegged knee extensor (1-KE) exercise ( 2 kg muscle mass). Peak power and peak pulmonary oxygen uptake (VO2peak) increased and muscle-specific VO2peak decreased with an increasing muscle mass involved in the exercise. Peak power and VO2peak were lower for CHF patients than HS, with values for CAD patients falling between CHF patients and HS. During bicycling, all groups utilized 24?29% of the muscle-specific VO2peak as measured during 1-KE exercise, with no difference between the groups. Hence, the muscle metabolic reserve capacity during whole body exercise is not different between CHF patients and HS, indicating that appropriately medicated and stable post-infarction CHF patients are not more limited by intrinsic skeletal muscle properties during whole body exercise than HS.

• Losnegard, Thomas; Mikkelsen, Kristin L.; Rønnestad, Bent R.; Hallén, Jostein; Rud, Bjarne & Raastad, Truls (2011). The effect of heavy strength training on muscle mass and physical performance in elite cross country skiers. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 21(3), s. 389–401. doi: 10.1111/j.1600-0838.2009.01074.x. Vis sammendrag

  To investigate the effect of supplementing high-volume endurance training with heavy strength training on muscle adaptations and physical performance in elite cross country skiers. Eleven male (18–26 years) and eight female (18–27 years) were assigned to either a strength group (STR) (n=9) or a control group (CON) (n=10). STR performed strength training twice a week for 12 weeks in addition to their normal endurance training. STR improved 1 repetition maximum (RM) for seated pull-down and half squat (19±2% and 12±2%, respectively), while no change was observed in CON. Cross-sectional area (CSA) increased in m. triceps brachii for both STR and CON, while there was no change in the m. quadriceps CSA. VO2max during skate-rollerskiing increased in STR (7±1%), while VO2max during running was unchanged. No change was observed in energy consumption during rollerskiing at submaximal intensities. Double-poling performance improved more for STR than for CON. Both groups showed a similar improvement in rollerski time-trial performance. In conclusion, 12 weeks of supplemental heavy strength training improved the strength in leg and upper body muscles, but had little effect on the muscle CSA in thigh muscles. The supplemental strength training improved both VO2max during skate-rollerskiing and double-poling performance.

• Rud, Bjarne; Christensen, Carl Christian; Ryg, Morten; Edvardsen, A.; Skumlien, Siri & Hallén, Jostein (2009). Higher skeletal muscular metabolic reserve capacity in COPD patients than healthy subjects. Scandinavian Journal of Medicine & Science in Sports. ISSN 0905-7188. 19(6), s. 857–864. doi: 10.1111/j.1600-0838.2008.00846.x. Vis sammendrag

  We investigated the interaction between skeletal muscle exercise capacity and central restrictions using exercise modalities, which recruit differing levels of muscle mass in eight patients chronic obstructive lung disease (COPD) (FEV1% of predicted; 35 [SE 4%]) and eight healthy controls. Subjects performed conventional bicycling, two-leg knee extensor (2-KE) and single-leg knee extensor (1-KE) exercises. Maximal values for pulmonary O2 (VO2max), power output, blood lactate, heart rate, blood pressure, and arterial oxygen saturation of hemoglobin were registered. VO2max in controls was 2453 (210), 1468 (124), and 976 (76) mL/min during bicycling, 2-KE and 1-KE, respectively. The COPD patients achieved 48% (P<0.05), 62% (P<0.05), and 81% (P=0.10) of the control values. The mass-specific VO2max (VO2max/exercising muscle mass) during 1-KE was 345 (25) and 263 (30) mL/kg/min (P<0.05) in controls and COPD patients, respectively. During 2-KE the controls and COPD patients achieved 85% (4%) and 67% (5%) (P=0.06) of the mass-specific O2 during 1-KE, while during bicycling they achieved 31% (2%) and 17% (1%) (P<0.05), respectively. The COPD patients have central restrictions when exercising with a relatively small muscle mass (2-KE) and have a higher muscular metabolic reserve capacity than controls during whole body exercise.

• Rud, Bjarne & Hallén, Jostein (2009). Is the balance between skeletal muscular metabolic capacity and oxygen supply capacity the same in endurance trained and untrained subjects? European Journal of Applied Physiology. ISSN 1439-6319. 105(5), s. 679–685. doi: 10.1007/s00421-008-0947-8. Vis sammendrag

  We attempted to test whether the balance between muscular metabolic capacity and oxygen supply capacity in endurance-trained athletes (ET) differs from that in a control group of normal physically active subjects by using exercises with different muscle masses. We compared maximal exercise in nine ET subjects [Maximal oxygen uptake (VO(2)max) 64 ml kg(-1) min(-1) +/- A SD 4] and eight controls (VO(2)max 46 +/- A 4 ml kg(-1) min(-1)) during one-legged knee extensions (1-KE), two-legged knee extensions (2-KE) and bicycling. Maximal values for power output (P), VO(2)max, concentration of blood lactate ([La-]), ventilation (VE), heart rate (HR), and arterial oxygen saturation of haemoglobin (SpO(2)) were registered. P was 43 (2), 89 (3) and 298 (7) W (mean +/- A SE); and VO(2)max: 1,387 (80), 2,234 (113) and 4,115 (150) ml min(-1)) for controls in 1-KE, 2-KE and bicycling, respectively. The ET subjects achieved 126, 121 and 126% of the P of controls (p < 0.05) and 127, 124, and 117% of their VO(2)max (p < 0.05). HR and [La-] were similar for both groups during all modes of exercise, while VE in ET was 147 and 114% of controls during 1-KE and bicycling, respectively. For mass-specific VO(2)max (VO(2)max divided by the calculated active muscle mass) during the different exercises, ET achieved 148, 141, and 150% of the controls' values, respectively (p < 0.05). During bicycling, both groups achieved 37% of their mass-specific VO2 during 1-KE. Finally we conclude that ET subjects have the same utilization of the muscular metabolic capacity during whole body exercise as active control subjects.

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• Rønnestad, Bent R.; Rønnestad, Bent R.; Losnegard, Thomas J.; Hallén, Jostein; Hallén, Jostein & Raastad, Truls [Vis alle 8 forfattere av denne artikkelen] (2009). The effect of heavy strength training on muscle adaptations and performance in elite cross-country skiers.
• Slettaløkken, Gunnar; Rud, Bjarne & Hallén, Jostein (2009). The balance between central and peripheral limitation for VO2max in heart and lung patients, and endurance trained subjects.
• Slettaløkken, Gunnar; Rehn, Tommy A; Munkvik, Morten; Rud, Bjarne; Søkjer-Petersen, Martin & Lunde, Per-Kristian [Vis alle 9 forfattere av denne artikkelen] (2009). Similar skeletal muscle metabolic reserve capacity in heart failure patients and healthy subjects. Vis sammendrag

  It is suggested that that patients with congestive heart failure (CHF) are more peripherally limited during exercise than healthy subjects (HS), due to intrinsic alterations in the skeletal muscle. Therefore we investigated the balance between peripheral and central limitations and the effect of 6 weeks of one-legged knee extensor (1-KE) endurance training. HS (n=13), patients with coronary artery disease (CAD, n=9) and CHF (n=10) were compared. One leg was trained (TL) and the untrained leg served as control (CL). Maximum values of VO2 (VO2max) for HS was 1164 (83) (mean, SE), 1579 (82) and 2359 (135) mL*min-1 during 1-KE, two legged knee extensor (2-KE) exercise and cycle ergometer exercise respectively. Corresponding values for CAD was not different from HS while CHF patients achived 66% (p<0.05), 73% (p<0.05) and 64% (p<0.05) of HS, respectively. For HS, muscle VO2max was 378 (37), 283 (24) and 84 (6) mL*kg-1*min-1 during 1-KE, 2-KE and cycle ergometer exercise respectively. Corresponding values for CAD was not different from HS while CHF patients achieved 71% (p<0.05), 79% (ns) and 70% (p<0.05) of HS. Mass-specific VO2max during 2-KE and cycle ergometer was 83% and 25% of 1-KE (CL) exercise, respectively with no difference between groups. Hence the metabolic reserve during 2-KE and bicycling was similar between the groups. After the training period the mass-specific VO2max was 12% higher (P<0.05) in TL compared to CL only for CHF patients. Therefore the metabolic reserve in TL compared to CL was 15% and 4% higher during 2-KE and bicycling (p<0.05), respectively for the CHF patients. In conclusion, CHF patients had a reduced work capacity and muscular metabolic capacity that increased in response to training. Importantly, muscular reserve capacity was not lower in CHF patients, suggesting that CHF patients are not more peripherally limited than HS.

• Rud, Bjarne & Hallén, Jostein (2009). The balance between central and peripheral limitation for VO2max in heart and lung patients, and endurance trained subjects.
• Rud, Bjarne & Hallén, Jostein (2009). The balance between central and peripheral limitation for VO2max in heart and lung patients, and endurance trained subjects.
• Slettaløkken, Gunnar; Rehn, Tommy A; Munkvik, Morten; Rud, Bjarne; Nymark, Bernt Sivert & Svarstad, Sjur Ole [Vis alle 11 forfattere av denne artikkelen] (2009). Muscular exercise capacity in patients with congestive heart failure and adaptations to one-legged knee extension endurance training. Vis sammendrag

  Congestive heart failure patients (CHF) are characterized by a low work capacity even during exercise with a small muscle mass (~2kg) when oxygen supply is not limited by cardiac output. We wanted to investigate whether CHF patients have a normal response to endurance training as compared to healthy subjects (HS). Work capacity as well as metabolic- and hemodynamic adoptions in the skeletal muscle was evaluated during fatiguing exercise. Nine CHF patients and eleven HS performed six weeks of supervised one-legged knee extension (1-KE) endurance training (TL) four days a week, leaving the untrained leg as control (CL). After the training period, the subjects performed two-legged knee extension (2-KE) exercise on two submaximal intensities to test work economy, and a 1-KE time to exhaustion (TTE) endurance test (~14 min) with TL and CL separately. Leg oxygen uptake (VO2) was measured invasively in both legs. Biopsies from vastus lateralis and CT scan of quadriceps femoris (QF) were obtained for both legs after the training period. In the endurance tests the workload in CL was 23.1 (1.9) (mean ± SE) and 34.3 (1.8) W for CHF patients and HS respectively (p<0.01) while TTE was not different (11.5 (2.9) and 13.9 (3.3) min for HS and CHF, respectively). Hence work capacity was lower in CHF patients. To avoid TTE longer than 60 min in TL, workload was set based on pretests and was 7.6 (1.4)% and 16.4 (3.1)% higher in TL than in CL in HS and CHF patients respectively (p<0.01). Despite this, TTE was 0.8 (2.9) (ns) and 2.8 (1.0) (p<0.05) min longer in TL than CL for HS and CHF patients respectively. This demonstrates a training induced increase in work capacity that was higher in CHF patients than HS (p<0.05). Evaluated from VO2 during 2-KE on submaximal intensities, the two groups showed same work economy which was unaltered by training. At exhaustion, leg blood flow and VO2 in CHF patients was 72 and 70% of that of HS respectively, and both variables were related to the mass of QF (R=0.57 and R=0.77 respectively; p<0.01). Hence leg perfusion and mass specific VO2 was not different between the groups. CHF patients had a higher oxygen extraction in TL compared to CL, but none of the groups showed any leg differences in blood flow or VO2. Number of capillaries around muscle fibers was lower for CHF patients than HS (86% of HS p<0.05) with no differences between legs. There was 65 (4)% and 58 (2)% muscle fiber type II in CHF patients and HS, respectively (ns) with no differences between legs. Fiber area and citrate synthase activity was the same between groups and legs. In conclusion CHF patients have a lower work capacity during one legged exercise which was related to active muscle mass involved. In contrast to HS, CHF patients increased O2-extraction in trained leg, but no other changes in metabolic or hemodynamic variables were detected. However, CHF patients increased their work capacity even more than HS.

• Slettaløkken, Gunnar; Munkvik, Morten; Rehn, Tommy A; Rud, Bjarne; Leirstein, Svein & Lunde, Per-Kristian [Vis alle 9 forfattere av denne artikkelen] (2008). Muscle fatigue in heart failure patients. Vis sammendrag

  Congestive heart failure (CHF) is characterized by low work capacity caused not only by the failing heart but possibly also by alterations in the skeletal muscles. This study investigates whether skeletal muscles of CHF patients are more fatigable than those of healthy subjects (HS) during intermittent isometric exercise. To minimize any limitation of performance by restricted cardiac output, exercise was performed by one leg¿s quadriceps muscle. Six CHF patients and six age matched healthy subjects performed right leg intermittent 6 seconds isometric knee extensor contractions every 10 seconds. The workload was chosen so that the subject was exhausted after 7-18 min. Maximal voluntary contraction (MVC) and electrical stimulation of the muscle at 20 and 50 Hz were performed before the exercise, at 3 and 9 min of exercise, and immediately after exhaustion. MVC tended to be lower in CHF patients compared to HS. When corrected for a lower muscle cross sectional area (CSA), there was no difference. MVC per CSA fell by 35 ±18 (mean ±SD) and 28 ±12 % for CHF and HS respectively from rest to exhaustion which was not significantly different (NS). Absolute workload, but not relative or time to exhaustion, was significantly different for CHF patients compared to HS (216 ¿64 N vs. 312 ¿71 N, p<0.05; 43 ¿10 % vs. 47 ¿7 % of MVC, NS and 15 ¿3 vs. 14 ¿4 min, NS; respectively). Electrical stimulation revealed a low-frequency fatigue since the ratio between the forces recorded at 20 and at 50 Hz fell during the exercise. The fall of 20/50 Hz force-ratio was not different between the two groups. We conclude that skeletal muscle of CHF patients have lower capacity for isometric exercise due to smaller CSA, but they are not more fatigable than in HS.

• Hallén, Jostein; Hallén, Jostein; Losnegard, Thomas J.; Mikkelsen, Kristin L.; Rønnestad, Bent R. & Rønnestad, Bent R. [Vis alle 16 forfattere av denne artikkelen] (2007). Effects of 12 weeks of heavy strength training on muscle strength and performance in elite cross-country skiers.
• Rud, Bjarne; Strand, Lars Erik; Nilsson, Johnny Erik; Secher, Niels H; Smith, Gerald A. & Hallén, Jostein (2006). Double poling at submaximal intensity: Mechanical power and oxygen uptake distribution, International Congress on Science and Nordic Skiing, 18-20. juni 2006. Department of Biology of Physical Activity, University of Jyväskylä.
• Rud, Bjarne; Strand, Lars Erik; Nilsson, Johnny Erik; Smith, Gerald A.; Secher, Niels H & Hallén, Jostein (2005). Double Poling at Submaximal Intensity: Mechanical Power and Oxygen Uptake Distribution. Vis sammendrag

  Previous studies have shown that not only the arms, but also the legs show significant muscle activity during cross country double poling. The purpose of the present study was to examine the arm and leg oxygen uptake distribution during different exercise intensities. Eight male cross-country skiers (mean +/- SD) 24 +/- 7 yr, 178 +/- 6 cm, VO2max 66 +/- 5 ml/kg?min performed low (54 +/- 5% of VO2max poling) and moderate (76 +/- 7%) intensity steady state double poling exercise on a double poling ergometer (modified Concept2) over two 8-10 minute trials. From catheters in an artery, one arm vein and one leg vein, blood samples were drawn after 3 and 6 min of exercise. Blood flow was determined by thermodilution technique simultaneously in both veins, immediately after blood samples were drawn. Oxygen uptake was calculated from a-v O2 diff and blood flow. Measurements of kinematic and kinetic characteristics included pole, elbow, hip and knee angles, vertical displacement of the pelvis, horizontally applied poling force and horizontal displacement. Low intensity workload trials were about 82 watts (range 66 - 97 watts) while the moderate intensity trials were at 117 (79 - 143) watts. Corresponding oxygen uptakes during low intensity exercise were 0.71 +/- 0.07 Lxmin-1 and 0.80 +/- 0.06 Lxmin-1 in arms and legs, respectively (ns) while during moderate exercise these were 0.86 +/- 0.08 Lxmin-1 and 1.24 +/- 0.07 Lxmin-1 (p < 0.01) (mean +/- SE). The oxygen uptake increases from low to moderate intensity were 22 +/- 7% (p < 0.05) and 60 +/- 10% (p < 0.01) in arms and legs, respectively. The increase in oxygen to the legs corresponded with increased mechanical work by the legs working against gravity. Leg work per stroke increased from 69.9 +/- 6.7 J to 100.0 +/- 9.6 J in the moderate trials (p < 0.01). Kinematic changes associated with increased workload included increased horizontal poling displacement (1.41 vs. 1.47 m, p < 0.02) while trunk, shoulder, elbow and pole ranges of motion were unchanged. The main finding in this study was the pronounced greater increase in oxygen uptake in legs than arms as exercise intensity increased from low to moderate levels in simulated ski double poling. The different responses of arms and legs were related to changes in technique toward more mechanical work done by the legs while trunk and arm motions changed relatively little. Andersen P & Saltin B (1985). Maximal perfusion of skeletal muscle in man. J Physiol 366: 233-249. Calbet JA, Jensen-Urstad M, van HG, Holmberg HC, Rosdahl H, & Saltin B (2004). Maximal muscular vascular conductances during whole body upright exercise in humans. J Physiol 558: 319-331. Holmberg HC, Lindinger S, Stoggl T, Eitzlmair E, & Muller E (2005). Biomechanical analysis of double poling in elite cross-country skiers. Med Sci Sports Exerc 37: 807-818.

• Rud, Bjarne; Myklebust, Paul Johan & Hallén, Jostein (2005). Training induced increase in maximal oxygen uptake is due to a balanced increase in both metabolic and oxygen supply capacity. Vis sammendrag

  In the last decades several studies strongly suggest that muscular maximal oxygen uptake are oxygen supply limited during whole body exercise. Despite this it has been argued that endurance training leads to a switch from metabolic to oxygen supply limitation during whole body exercise (Wagner, 2000). The purpose of this study was to test if the ratio of metabolic to oxygen supply capacity differs between endurance trained and normally active subjects. Nine endurance trained subjects (mean+/-SD 25+/-3 yr, 180+/-9 cm, VO2max 64+/-4 ml/kg.min) and eight normal physical active controls (27+/-3 yr, 181+/-9 cm, VO2max 46+/-4 ml), performed single-legged knee extensions (1-leg) and bicycling with stepwise increments of intensity until exhaustion (9-12 min): Pulmonary oxygen uptake (VO2) were measured continuously before and during the exercise tests. From rest 1-leg VO2 increased by (mean+/-SE) 1059+/-69 and 1473+/-80 ml/min (p<0.05) (Fig.1) in controls and trained, respectively. 1-leg quadriceps muscle mass was estimated to 2.8+/-0.1 and 2.5+/-0.1 kg and the maximal VO2 per kg muscle was calculated to 387+/-27 and 585+/-25 ml/min (p<0.05), respectively. The exercising muscle mass during bicycling was set to 25% of body mass, and the mass specific VO2 during bicycling were estimated to 171+/-6 (controls) and 237+/-6 (trained) ml/min (p<0.05), 46+/-4 and 41+/-2% of the 1-leg mass specific VO2, respectively (ns). The endurance trained group showed both higher metabolic and oxygen supply capacity than controls, evidenced by higher mass specific VO2 during 1-leg exercise and higher VO2max during bicycling. However, the difference between trained and untrained are suggested to be balanced and in support of the symmorphosis concept which advocate a close match between all links in the O2 transporting chain (Weibel et al.1991), indicated by no difference in mass specific VO2 during bicycling relative to mass specific VO2 during 1-leg in the two groups. In conclusion this study does not support a switch from metabolic to oxygen supply limitation in endurance trained subjects. Wagner PD (2000). New ideas on limitations to VO2max. Exerc Sport Sci Rev 28, 10-14. Weibel ER, Taylor CR, & Hoppeler H (1991). The concept of symmorphosis: a testable hypothesis of structure-function relationship. Proc Natl Acad Sci U S A 88, 10357-10361.

• Rud, Bjarne; Myklebust, Paul Johan & Hallén, Jostein (2005). Training induced increase in maximal oxygen uptake is due to a balanced increase in both metabolic and oxygen supply capacity. Vis sammendrag

  In the last decades several studies strongly suggest that muscular maximal oxygen uptake are oxygen supply limited during whole body exercise. Despite this it has been argued that endurance training leads to a switch from metabolic to oxygen supply limitation during whole body exercise (Wagner, 2000). The purpose of this study was to test if the ratio of metabolic to oxygen supply capacity differs between endurance trained and normally active subjects. Nine endurance trained subjects (mean+/-SD 25+/-3 yr, 180+/-9 cm, VO2max 64+/-4 ml/kg.min) and eight normal physical active controls (27+/-3 yr, 181+/-9 cm, VO2max 46+/-4 ml), performed single-legged knee extensions (1-leg) and bicycling with stepwise increments of intensity until exhaustion (9-12 min): Pulmonary oxygen uptake (VO2) were measured continuously before and during the exercise tests. From rest 1-leg VO2 increased by (mean+/-SE) 1059+/-69 and 1473+/-80 ml/min (p<0.05) (Fig.1) in controls and trained, respectively. 1-leg quadriceps muscle mass was estimated to 2.8+/-0.1 and 2.5+/-0.1 kg and the maximal VO2 per kg muscle was calculated to 387+/-27 and 585+/-25 ml/min (p<0.05), respectively. The exercising muscle mass during bicycling was set to 25% of body mass, and the mass specific VO2 during bicycling were estimated to 171+/-6 (controls) and 237+/-6 (trained) ml/min (p<0.05), 46+/-4 and 41+/-2% of the 1-leg mass specific VO2, respectively (ns). The endurance trained group showed both higher metabolic and oxygen supply capacity than controls, evidenced by higher mass specific VO2 during 1-leg exercise and higher VO2max during bicycling. However, the difference between trained and untrained are suggested to be balanced and in support of the symmorphosis concept which advocate a close match between all links in the O2 transporting chain (Weibel et al.1991), indicated by no difference in mass specific VO2 during bicycling relative to mass specific VO2 during 1-leg in the two groups. In conclusion this study does not support a switch from metabolic to oxygen supply limitation in endurance trained subjects. Wagner PD (2000). New ideas on limitations to VO2max. Exerc Sport Sci Rev 28, 10-14. Weibel ER, Taylor CR, & Hoppeler H (1991). The concept of symmorphosis: a testable hypothesis of structure-function relationship. Proc Natl Acad Sci U S A 88, 10357-10361.

• Hallén, Jostein; Foss, Øivind; Rud, Bjarne; Krustrup, Peter; Secher, Niels H & Müller, Erich [Vis alle 9 forfattere av denne artikkelen] (2003). Muscle efficiency was not changed by 7 weeks of endurance training. Vis sammendrag

  Introduction: An extensive research has been conducted on humans to study the effects of endurance training on maximal oxygen uptake. However, only a few studies have focused on how training effects muscle efficiency. The aim of the present study was therefore to study the effect of 7 weeks of endurance training on skeletal muscle efficiency. Methods: Six subjects of both sexes participated. Their age was 20-25 years, weight 66 (59-75) kg and maximal oxygen uptake 59 (50-72) ml/kg•min. Subjects trained one leg 40-100 min, four times per week, in 7 weeks on a cycle ergometer (Monark 818E). Training workload was 90 (75-115) W, corresponding to 70% (65-77) of maximal heart rate. After the training period, both legs were tested separately at three submaximal workloads (females n=3 at 40, 60 and 80 Watts, males n=3 at 50, 75 and 100 Watts) on an electromagnetically braked cycle ergometer at a constant cadence (80 rpm). Each workload lasted 8 min with 2 min rest in between. Blood samples were takenafter 3 and 6 min at each workload from vena femoralis in both legs and in one arteria brachialis. Blood flow was determined by the thermodilution technique simultaneously in the vena femoralis of both legs immediately after blood samples were taken. Skeletal muscle oxygen uptake and lactate release were calculated from arterial venous differences and leg blood flow. Pulmonary oxygen uptake was measured from 5-7.5 min. Results: There were no differences in blood flow, arterial venous oxygen difference (a-v O2 diff) or oxygen uptake (Fig. 1) at submaximal workloads between the trained and the untrained leg. Lactate release during exercise was markedly lower in the trained leg than in the untrained leg (p<0.05) (Fig. 1). An uptake of lactate was seen in the resting legs during exercise at the highest workloads (p<0.05). There was no statistical difference in pulmonary oxygen uptake during exercise with the trained and untrained leg, respectively. Discussion/Conclusion: Leg oxygen uptake at three submaximal workloads was not different in the trained and untrained leg. However, less lactate was released from the trained leg compared to the untrained leg while exercising. However, the decreased anaerobic metabolism is not big enough to result in a significant reduction in the total energy turnover rate and therefore it is concluded that the type of training conducted in this study do not effect muscle efficiency.

• Rud, Bjarne; Foss, Øivind; Krustrup, Peter; Secher, Niels H; Hallén, Jostein & Müller, Erich [Vis alle 9 forfattere av denne artikkelen] (2003). Maximal leg oxygen uptake during whole body exercise - effect of training. Vis sammendrag

  Despite extensive research over the last 70 yr it is still debated whether muscle VO2max is determined by the cardiorespiratory systems ability to deliver oxygen or by the muscles capacity to utilize oxygen. The purpose of the present study was to examine the effect of training on muscle oxygen uptake during high intensity whole body exercise. Five subjects 23 (20-25) yr, 66 (59-74) kg and VO2max 59 (50-72) ml/kg•min trained one leg 4 times pr week in 7 weeks. Mean training volume was 1150 (600-1800) kJ/week , workload 90 (75-115) W corresponding to 70 (65-76) % of maximal heart rate. After the training period, both legs were tested simultaneously on a cycle ergometer at a workload corresponding to 91±2.2% (mean±SD) of VO2max until exhaustion (7±1 min). With visible feedback from strain gauges at the crank arms, subjects kept power output equal in both legs. From catheters in one artery (brachialis) and both vena femoralis, blood samples were drawn after 3, 41/2 and 6 min of exercise. Blood flow was determined by thermodilution technique, simultaneously in both vena femoralis, immediately after blood samples were drawn. Skeletal muscle VO2 was calculated from arterial venous difference and leg blood flow. The maximal pulmonary oxygen uptake din not changed during the training period. Four out of five subjects had higher oxygen uptake, 3 subjects had higher blood blood flow and all of the subjects had larger a-v O2 diff in the trained leg. There were no statistical differences. Thesubjects in this study were moderate to highly endurance trained. Four out of five subjects had a higher oxygen uptake during exhaustive bicycling in the trained leg compared to the untrained leg. The subject who did not achieve a higher oxygen uptake in the trained leg, was the subject with the highest maximal oxygen uptake (72 ml/kg•min). The preliminary data suggest that training increases leg oxygen uptake during maximal whole body exercise in moderate endurance trained subjects. This indicates that peripheral factors affects maximal muscle oxygen uptake even during whole body exercise.

• Foss, Øivind; Rud, Bjarne; Krustrup, Peter; Secher, Niels H; Hallén, Jostein & Müller, Erich [Vis alle 9 forfattere av denne artikkelen] (2003). Skeletal muscle oxygen uptake and blood flow at different contraction frequencies. Vis sammendrag

  A considerable effort has been put into studying muscle efficiency in humans during exercise at different speeds of shortening. Traditionally, whole body exercise such as cycling at a constant workload has been used in which pulmonary oxygen uptake hasbeen shown to increase as contraction frequency (cadence) increases. However, it is not clear whether the differences in pulmonary oxygen uptake reflect a difference in the oxygen uptake of the contracting muscle. The aim of the present study was to test the hypothesis that human skeletal muscle oxygen uptake are elevated at high (100 rpm) compared to moderate (80 rpm) contraction frequencies. Six subjects of both sexes participated. Their age was 23 (20-25) years, weight 66 (59-75) kg and maximal oxygen uptake 59 (50-72) ml/kg•min. Both legs of each subject were separately tested at both 80 and 100 rpm (randomised order) on an electromagnetically braked cycle ergometer (Lode Excalibur Sport) and pooled together in a subsequent analysis. Externalpower was 60 Watt for females and 75 Watt for males at both cadences. Each workload lasted 8 min and was separated with 5 min rest in between. Blood samples were taken after 3 and 6 min at each workload from one artery (brachialis) and both vena femoralis. Blood flow was determined by the thermodilution technique (Andersen & Saltin 1985) in vena femoralis immediately after blood samples were taken. Leg muscle oxygen uptake and lactate release were calculated from arterial venous differences and leg blood flow. Leg oxygen uptake was 12.6% higher at 100 compared to 80 rpm (p<0.05). This was mainly caused by a 9.6% higher blood flow at 100 compared to 80 rpm. The remaining difference was explained by a higher a-v O2 diff at 100 rpm partially due to ahigher arterial [Hb] compared to 80 rpm (13.5 vs. 13.3 g/dl, p<0.05). Also leg lactate release was higher at 100 compared to 80 rpm (p<0.05). This study supports the hypothesis that skeletal muscle oxygen uptake are greater at high (100 rpm) comparedto moderate (80 rpm) contraction frequencies (cadences). This difference was explained mainly by a larger leg blood flow. Also leg lactate release was considerably higher at 100 compared to 80 rpm. Together these data reveals that the energy requirement ofthe exercising muscles is higher at a high compared to a moderate contraction frequency.

• Rud, Bjarne; Christensen, Carl Christian; Ryg, Morten; Skumlien, Siri & Hallén, Jostein (2002). Høy metabolsk reserve kapasitet hos kronisk obstruktiv lunge (KOLS) pasienter. Vis sammendrag

  KOLS pasienter har betydelig redusert arbeidskapasitet i forhold til friske. I tillegg til redusert lunge og kardiovaskulær funksjon har de også endringer i skjelettmuskulaturen; redusert konsentrasjon av oksidative enzymer, lav kapillærtetthet, lav andel type I fibre og redusert tverrsnittsareal. Disse endringene gir redusert muskulær metabolsk kapasitet, og i dette studiet ønsket vi å teste om dette kan være årsak til redusert arbeidskapasitet. Åtte KOLS pasienter (59+/-6år, FEV1 35+/-8% av predikert) og åtte friske sedate kontroller (51+/-8år) gjennomførte arbeidstester med trinnvis økende intensitet til utmattelse (normalt 9-12 min) i tre ulike arbeidsmodeller: Ett-beins kneekstensjon (1-BK), to-beins kneekstensjon (2-BK) og ergometersykling (sykling). Pulmonalt oksygenopptak (VO2), hjertefrekvens (HF) og arterielt blodtrykk (BT) ble målt kontinuerlig under testene. VO2 i hvile var 321+/-25 (SE) og 352&#61617;34 ml.min-1 for kontroller og KOLS pasienter, (ns). Ved 1-BK økte VO2peak med 667+/-66 (kontroller) og 452+/-71 mlxmin-1 (KOLS). Økningen i VO2peak fra 1-BK til 2-BK var 73+/-10 % av økningen fra hvile til 1-BK hos kontrollene, mens den tilsvarende økningen bare var 34+/-13 % for KOLS pasientene. Ved sykling var VO2peak respektivt 249+/-6 og 145+/-4 % av 1-BK VO2peak hos kontrollene og KOLS pasientene. Massen til quadriceps ble estimert til 2.0+/-0.2 (kontroller) og 1.7+/-0.3 kg (KOLS pasienter). VO2peak per kg muskel ble under 1-BK kalkulert til respektivt 348+/-25 og 241+/-26 ml.min-1. Under sykling brukte de arbeidende musklene hos kontrollene 30% per kg aktiv muskel (muskelmasse satt til 25% av kroppsvekt) av 1-BK massespesifikke VO2peak, mens KOLS-pasientene brukte bare 19%. KOLS pasientene hadde lavere HF og høyere BT enn kontrollene under arbeidene. Konkluderende har KOLS pasienter større metabolsk reservekapasiet enn kontroller under arbeid med hele kroppen og musklene deres er ikke så detrent som tidligere antatt.

• Rud, Bjarne; Skumlien, Siri; Ryg, Morten; Christensen, Carl Christian & Hallén, Jostein (2002). Exercise Capacity in Chronic Obstructive Pulmonary Disease (COPD) Patients.
• Rud, Bjarne; Christensen, Carl Christian; Ryg, Morten; Skumlien, Siri & Hallén, Jostein (2002). Higher Metabolic Reserve Capacity in Chronic Obstructive Pulmonary Disease (COPD) Patients. Vis sammendrag

  HIGH METABOLIC RESERVE CAPACITY IN CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD) PATIENTS B. Rud1, C. C. Christensen2, M. Ryg2, S. Skumlien2 and J. Hallén1 1Norwegian University of Sport and Physical Education, Oslo, Norway; 2The Glittre Clinic, Norway In COPD patients exercise capacity is markedly reduced compared to healthy aged-matched controls. This is due to pulmonary and cardiovascular dysfunctions. However, COPD patients also have alteration in the muscles, such as low levels of oxidative enzymes, low capillary density, low fraction of type I fibres and decreased fiber cross-sectional area (Jakobsson et al., 1990; Whittom et al., 1998). This probably leads to reduced metabolic capacity and whether these peripheral changes limit the exercise capacity has being discussed (Richardson, 1999). In this study we attempted to test if skeletal muscle limits exercise capacity in COPD patients. Eight COPD patients and eight healthy sedentary controls (mean+/-SD 59&#61617;6yr, FEV1 35+/-8% of predicted and 51+/-8yr, FEV1 103+/-12% of predicted, respectively) performed three different exercise tests with stepwise increments of intensity until exhaustion (defined as inability to maintain pedal frequency, normally lasting 9-12 min): single-legged knee extension (SLE), two legged knee extension (TLE) and bicycling. All tests were performed in one day with at least 1 hour’s rest in between. Pulmonary oxygen uptake (VO2), heart rate (HR) and arterial blood pressure (BP) were measured continuously before, during and 6 min after the exercise tests. VO2 at rest, sitting on the ergometers, was (mean+/-SE) 321+/-25 and 352+/-34 ml.min-1 in controls and COPD patients, respectively (ns). At SLE VO2peak increased by 667+/-66 (controls) and 452+/-71 mlxmin-1 (COPD). The increase in VO2peak from SLE to TLE was 73+/-10 % of the increase from rest to SLE in the controls while the corresponding value in COPD was only 34+/-13 %. With bicycling VO2peak was 249+/-6 and 145+/-4 % of SLE VO2peak in controls and COPD patients, respectively. From anthropometrical measures quadriceps muscle mass can be calculated to 2.0+/-0.2 and 1.7+/-0.3 kg in controls and COPD. Peak VO2 per kg muscle mass during SLE was calculated to 348+/-25 and 241+/-26 in the two groups, respectively. During bicycling, the exercising muscles of controls utilized 30% per kg active muscle mass (set to 25% of body weight) of the SLE mass specific VO2peak while COPD patients utilized only 19%. The COPD patients showed lower HR and higher BP than controls during exercise. In conclusion, COPD patients have larger metabolic reserve capacity than controls during whole body exercise. The muscles of COPD patients are not as seriously detrained as previously suggested. REFERENCES Jakobsson, P., Jorfeldt, L., & Brundin, A. (1990). Eur.Respir.J. 3, 192-196. Richardson, R. S. (1999). J Appl.Physiol 86, 1751-1753. Whittom, F., Jobin, J., Simard, P. M., Leblanc, P., Simard, C., Bernard, S., Belleau, R., & Maltais, F. (1998). Med.Sci.Sports Exerc. 30, 1467-1474

• Rud, Bjarne; Raastad, Truls & Hallén, Jostein (2001). Effect of strength exercise intensity on neuromuscular fatigue and recovery.
• Rud, Bjarne (2011). The significance of the skeletal muscular oxidative capacity during whole body exercise. Norwegian School of Sport Sciences. ISSN 978-82-502-0472-0. Vis sammendrag

  The present thesis consists of four studies with the main objective to examine the significance of the skeletal muscular metabolic capacity during whole body exercise. Exercise capacity was studied in chronic obstructive lung disease (COPD) patients and a control group in study I, and in endurance‐trained subjects and normal physical active subjects in study II. In both studies, muscular metabolic capacity was quantified during exercise with a small muscle mass (1.7‐2.8 kg) to avoid the issue of muscular oxygen uptake being limited by oxygen supply. Thereafter, we tested how much the muscular metabolic capacity could be exploited during whole body exercise (bicycling). Exploitation less than 100% indicated a muscular metabolic reserve probably due to oxygen supply limitations. The muscular metabolic capacity ranged from 264 to 570 ml.kg‐1.min‐1 for the four groups. However, there was less variation in the relative exploitation of the muscular metabolic capacity during whole body exercise for the healthy groups (31%‐37%), while this percentage was smaller (17%) for the COPD patients. Based on these results, we concluded that the exploitation of the muscular metabolic capacity was relatively equal for the healthy groups despite large differences in age and maximal oxygen uptake (VO2max). The COPD patients were least capable of exploiting the muscular metabolic capacity during bicycling and consequently, they had a relatively higher muscular metabolic reserve during whole body exercise compared with healthy subjects.

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