Christian Helland

• Lindberg, Kolbjørn Andreas; Solberg, Paul Andre; Bjørnsen, Thomas; Helland, Christian; Rønnestad, Bent & Frank, Martin Thorsen [Vis alle 13 forfattere av denne artikkelen] (2022). Strength and Power Testing of Athletes: Associations of Common Assessments Over Time. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 17(8), s. 1280–1288. doi: 10.1123/ijspp.2021-0557. Vis sammendrag

  Purpose: This study examined the associations among common assessments for measuring strength and power in the lower body of high-performing athletes, including both cross-sectional and longitudinal data. Methods: A total of 100 participants, including both male (n = 83) and female (n = 17) athletes (21 [4] y, 182 [9] cm, 78 [12] kg), were recruited for the study using a multicenter approach. The participants underwent physical testing 4 times. The first 2 sessions (1 and 2) were separated by ∼1 week, followed by a period of 2 to 6 months, whereas the last 2 sessions (3 and 4) were also separated by ∼1 week. The test protocol consisted of squat jumps, countermovement jumps, jump and reach, 30-m sprint, 1-repetition-maximum squat, sprint cycling, and a leg-press test. Results: There were generally acceptable correlations among all performance measures. Variables from the countermovement jumps and leg-press power correlated strongly with all performance assessments (r = .52–.79), while variables from sprint running and squat-jump power displayed more incoherent correlations (r = .21–.82). For changes over time, the correlations were mostly strong, albeit systematically weaker than for cross-sectional measures. Conclusions: The associations observed among the performance assessments seem to be consistent for both cross-sectional data and longitudinal change scores. The weaker correlations for change scores are most likely mainly caused by lower between-subjects variations in the change scores than for the cross-sectional data. The present study provides novel information, helping researchers and practitioners to better interpret the relationships across common performance assessment methods.

• Lindberg, Kolbjørn Andreas; Solberg, Paul Andre; Bjørnsen, Thomas; Helland, Christian; Rønnestad, Bent & Frank, Martin [Vis alle 13 forfattere av denne artikkelen] (2022). Strength and Power Testing of Athletes: A Multicenter Study of Test-Retest Reliability. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 17(7), s. 1103–1110. doi: 10.1123/ijspp.2021-0558. Fulltekst i vitenarkiv Vis sammendrag

  Purpose:This study examined the test–retest reliability of common assessments for measuring strength and power of the lowerbody in high-performing athletes.Methods:A total of 100 participants, including both male (n=83) and female (n=17) athletes(21 [4] y, 182 [9] cm, and 78 [12] kg), were recruited for this study, using a multicenter approach. The participants underwentphysical testing 4 times. Thefirst 2 sessions (1 and 2) were separated by∼1 week, followed by a period of 2 to 6 months, whereasthe last 2 sessions (3 and 4) were again separated by∼1 week. The test protocol consisted of squat jumps, countermovementjumps, jump and reach, 30-m sprint, 1-repetition-maximum squat, sprint cycling, and a leg-press test.Results:The typical error(%) ranged from 1.3% to 8.5% for all assessments. The change in means ranged from−1.5% to 2.5% for all assessments, whereasthe interclass correlation coefficient ranged from .85 to .97. The smallest worthwhile change (0.2 of baseline SD) ranged from1.2% to 5.0%. The ratio between the typical error (%) and the smallest worthwhile change (%) ranged from 0.5 to 1.2. Whenobserving the reliability across testing centers, considerable differences in reliability were observed (typical error [%] ratio: 0.44–1.44).Conclusions:Most of the included assessments can be used with confidence by researchers and coaches to measurestrength and power in athletes. Our results highlight the importance of controlling testing reliability at each testing center and notrelying on data from others, despite having applied the same protocol.

• Rakovic, Elvir; Paulsen, Gøran; Helland, Christian; Haugen, Thomas André & Eriksrud, Ola (2022). Validity and Reliability of a Motorized Sprint Resistance Device. Journal of Strength and Conditioning Research. ISSN 1064-8011. 36(8), s. 2335–2338. doi: 10.1519/JSC.0000000000003830. Fulltekst i vitenarkiv Vis sammendrag

  An increasing number of sprint-related studies have used motorized devices to provide resistance while sprinting. The aim of this study was to establish within-session reliability and criterion validity of sprint times obtained from a motorized resistance device. Seventeen elite, female, handball players (22.9 ± 3.0 years; 176.5 ± 6.5 cm; 72.7 ± 5.5 kg; training volume 9.3 ± 0.7 hours per week) performed two 30-m sprints under 3 different resistance loading conditions (50, 80 and 110 N). Sprint times (t0–5m, t5–10m, t10–15m, t15–20m, t20–30m, and t0–30m) were assessed simultaneously by a 1080 Sprint motorized resistance device and a postprocessing timing system. The results showed that 1080 Sprint timing was equivalent to the postprocessing timing system within the limits of precision (±0.01 seconds). A systematic bias of approximately 0.34 ± 0.01 seconds was observed for t0–5m caused by different athlete location and velocity at triggering point between the systems. Coefficient of variation was approximately 2% for t0–5 and approximately 1% for the other time intervals, although standard error of measurement ranged from 0.01 to 0.05 seconds, depending on distance and phase of sprint. Intraclass correlation ranged from 0.86 to 0.95. In conclusion, the present study shows that the 1080 Sprint is valid and reliable for sprint performance monitoring purposes.

• Lindberg, Kolbjørn Andreas; Solberg, Paul; Bjørnsen, Thomas; Helland, Christian; Rønnestad, Bent & Frank, Martin Thorsen [Vis alle 12 forfattere av denne artikkelen] (2021). Force-velocity profiling in athletes: Reliability and agreement across methods. PLOS ONE. ISSN 1932-6203. 16(2). doi: 10.1371/journal.pone.0245791. Fulltekst i vitenarkiv Vis sammendrag

  The aim of the study was to examine the test-retest reliability and agreement across methods for assessing individual force-velocity (FV) profiles of the lower limbs in athletes. Using a multicenter approach, 27 male athletes completed all measurements for the main analysis, with up to 82 male and female athletes on some measurements. The athletes were tested twice before and twice after a 2- to 6-month period of regular training and sport participation. The double testing sessions were separated by ~1 week. Individual FV-profiles were acquired from incremental loading protocols in squat jump (SJ), countermovement jump (CMJ) and leg press. A force plate, linear encoder and a flight time calculation method were used for measuring force and velocity during SJ and CMJ. A linear regression was fitted to the average force and velocity values for each individual test to extrapolate the FV-variables: theoretical maximal force (F0), velocity (V0), power (Pmax), and the slope of the FV-profile (SFV). Despite strong linearity (R2>0.95) for individual FV-profiles, the SFV was unreliable for all measurement methods assessed during vertical jumping (coefficient of variation (CV): 14–30%, interclass correlation coefficient (ICC): 0.36–0.79). Only the leg press exercise, of the four FV-variables, showed acceptable reliability (CV:3.7–8.3%, ICC:0.82–0.98). The agreement across methods for F0 and Pmax ranged from (Pearson r): 0.56–0.95, standard error of estimate (SEE%): 5.8–18.8, and for V0 and SFV r: -0.39–0.78, SEE%: 12.2–37.2. With a typical error of 1.5 cm (5–10% CV) in jump height, SFV and V0 cannot be accurately obtained, regardless of the measurement method, using a loading range corresponding to 40–70% of F0. Efforts should be made to either reduce the variation in jumping performance or to assess loads closer to the FV-intercepts. Coaches and researchers should be aware of the poor reliability of the FV-variables obtained from vertical jumping, and of the differences across measurement methods.

• Helland, Christian; Midttun, Magnus; Sæland, Fredrik; Haugvad, Lars; Olstad, Daniela Schäfer & Solberg, Paul Andre [Vis alle 7 forfattere av denne artikkelen] (2020). A strength-oriented exercise session required more recovery time than a power-oriented exercise session with equal work. PeerJ. ISSN 2167-8359. 8. doi: 10.7717/peerj.10044. Fulltekst i vitenarkiv Vis sammendrag

  The present randomized cross-over controlled study aimed to compare the rate of recovery from a strength-oriented exercise session vs. a power-oriented session with equal work. Sixteen strength-trained individuals conducted one strength-oriented session (five repetitions maximum (RM)) and one power-oriented session (50% of 5RM) in randomized order. Squat jump (SJ), countermovement jump (CMJ), 20-m sprint, and squat and bench press peak power and estimated 1RMs were combined with measures of rate of perceived exertion (RPE) and perceived recovery status (PRS), before, immediately after and 24 and 48 h after exercise. Both sessions induced trivial to moderate performance decrements in all variables. Small reductions in CMJ height were observed immediately after both the strength-oriented session (7 ± 6%) and power-oriented session (5 ± 5%). Between 24 and 48 h after both sessions CMJ and SJ heights and 20 m sprint were back to baseline. However, in contrast to the power-oriented session, recovery was not complete 48 h after the strength-oriented session, as indicated by greater impairments in CMJ eccentric and concentric peak forces, SJ rate of force development (RFD) and squat peak power. In agreement with the objective performance measurements, RPE and PRS ratings demonstrated that the strength-oriented session was experienced more strenuous than the power-oriented session. However, these subjective measurements agreed poorly with performance measurements at the individual level. In conclusion, we observed a larger degree of neuromuscular impairment and longer recovery times after a strength-oriented session than after a power-oriented session with equal total work, measured by both objective and subjective assessments. Nonetheless, most differences were small or trivial after either session. It appears necessary to combine several tests and within-test analyses (e.g., CMJ height, power and force) to reveal such differences. Objective and subjective assessments of fatigue and recovery cannot be used interchangeably; rather they should be combined to give a meaningful status for an individual in the days after a resistance exercise session.

• Paulsen, Gøran; Eidsheim, Hedda; Helland, Christian; Seynnes, Olivier R.; Solberg, Paul Andre & Rønnestad, Bent (2019). Eccentric cycling does not improve cycling performance in amateur cyclists. PLOS ONE. ISSN 1932-6203. 14:e0208452(1), s. 1–15. doi: 10.1371/journal.pone.0208452. Fulltekst i vitenarkiv Vis sammendrag

  Eccentric cycling training induces muscle hypertrophy and increases joint power output in non-athletes. Moreover, eccentric cycling can be considered a movement-specific type of strength training for cyclists, but it is hitherto unknown if eccentric cycling training can improve cycling performance in trained cyclists. Twenty-three male amateur cyclists were randomized to an eccentric or a concentric cycling training group. The eccentric cycling was performed at a low cadence (~40 revolution per minute) and the intensity was controlled by perceived effort (12–17 on the Borgs scale) during 2 min intervals (repeated 5–8 times). The cadence and perceived effort of the concentric group matched those of the eccentric group. Additionally, after the eccentric or concentric cycling, both groups performed traditionally aerobic intervals with freely chosen cadence in the same session (4–5 x 4–15 min). The participants trained twice a week for 10 weeks. Maximal oxygen uptake (VO2max), maximal aerobic power output (Wmax), lactate threshold, isokinetic strength, muscle thickness, pedaling characteristics and cycling performance (6- and 30-sec sprints and a 20-min time trial test) were assessed before and after the intervention period. Inferences about the true value of the effects were evaluated using probabilistic magnitude-based inferences. Eccentric cycling induced muscle hypertrophy (2.3 ± 2.5% more than concentric) and augmented eccentric strength (8.8 ± 5.9% more than concentric), but these small magnitude effects seemed not to transfer into improvements in the physiological assessments or cycling performance. On the contrary, the eccentric training appeared to have limiting or detrimental effects on cycling performance, measured as Wmax and a 20-min time trial. In conclusion, eccentric cycling training did not improve cycling performance in amateur cyclists. Further research is required to ascertain whether the present findings reflect an actual lack of efficacy, negative effects or a delayed response to eccentric cycling training.

• Helland, Christian; Haugen, Thomas André; Rakovic, Elvir; Eriksrud, Ola; Seynnes, Olivier R. & Mero, Antti A. [Vis alle 7 forfattere av denne artikkelen] (2019). Force–velocity profiling of sprinting athletes: single-run vs. multiple-run methods. European Journal of Applied Physiology. ISSN 1439-6319. 119(2), s. 465–473. doi: 10.1007/s00421-018-4045-2. Vis sammendrag

  Purpose: This study explored the agreement between a single-run and a multiple-run method for force–velocity (Fv) profiling of sprinting athletes; we evaluated both absolute values and changes over time caused by sprint training. Methods: Seventeen female handball players (23 ± 3 years, 177 ± 7 cm, 73 ± 6 kg) performed 30 m un-resisted and resisted sprints (50, 80 and 110 N resistance) before and after an 8-week sprint training intervention. Two approaches were used to calculate theoretical maximal velocity (v0), horizontal force (F0), power (Pmax), and the force–velocity slope (SFv): (1) the single-run method, based on inverse dynamics applied to the centre-of-mass movement, was calculated from anthropometric and sprint split time data; and (2) the multiple-run method, where peak velocity from un-resisted and resisted sprints were plotted against the horizontal resistances. Results: Trivial differences in v0 (0.7%) were observed between the two calculation methods. Corresponding differences for F0, Pmax and SFv were 16.4, 15.6 and 17.6%, respectively (most likely; very large effect size). F0 showed poor agreement between the methods (r = 0.26 and 0.16 before and after the intervention). No substantial correlation between the changes (from pre- to post-training tests) in SFV calculated with the single-run and the multiple-run methods were observed (r = 0.02). Conclusions: This study revealed poor agreement between the Fv relationships of the investigated calculation methods. In practice, both methods may have a purpose, but the single-run and the multiple-run methods appear to measure somewhat different sprint properties and cannot be used interchangeably.

• Rakovic, Elvir; Paulsen, Gøran; Helland, Christian; Eriksrud, Ola & Haugen, Thomas (2018). The effect of individualised sprint training in elite female team sport athletes: A pilot study. Journal of Sports Sciences. ISSN 0264-0414. 36(24), s. 2802–2808. doi: 10.1080/02640414.2018.1474536. Fulltekst i vitenarkiv Vis sammendrag

  This study aimed to evaluate whether an individualised sprint-training program was more effective in improving sprint performance in elite team-sport players compared to a generalised sprint-training program. Seventeen elite female handball players (23 ± 3 y, 177 ± 7 cm, 73 ± 6 kg) performed two weekly sprint training sessions over eight weeks in addition to their regular handball practice. An individualised training group (ITG, n = 9) performed a targeted sprint-training program based on their horizontal force-velocity profile from the pre-training test. Within ITG, players displaying the lowest, highest and mid-level force-velocity slope values relative to body mass were assigned to a resisted, an assisted or a mixed sprint-training program (resisted sprinting in the first half and assisted sprinting in the second half of the intervention period), respectively. A control group (CG, n = 8) performed a generalised sprint-training program. Both groups improved 30-m sprint performance by ~1% (small effect) and maximal velocity sprinting by ~2% (moderate effect). Trivial or small effect magnitudes were observed for mechanical outputs related to horizontal force- or power production. All between-group differences were trivial. In conclusion, individualised sprint-training was no more effective in improving sprint performance than a generalised sprint-training program.

• Helland, Christian; Hole, Eirik; Olsson, Monica Charlotte; Seynnes, Olivier R.; Solberg, Paul Andre & Paulsen, Gøran (2016). Training Strategies to Improve Muscle Power: Is Olympic-style Weightlifting Relevant? Medicine & Science in Sports & Exercise. ISSN 0195-9131. 49(4), s. 736–745. doi: 10.1249/MSS.0000000000001145. Fulltekst i vitenarkiv Vis sammendrag

  Introduction: This efficacy study investigated the effects of (1) Olympic-style weightlifting (OWL), (2) motorized strength and power training (MSPT), and (3) free weight strength and power training (FSPT) on muscle power. Methods: Thirty-nine young athletes (20±3 yr.; ice hockey, volleyball and badminton) were randomized into the three training groups. All groups participated in 2-3 sessions/week for 8 weeks. The MSPT and FSPT groups trained using squats (two legs and single leg) with high force and high power, while the OWL group trained using clean and snatch exercises. MSPT was conducted as slow-speed isokinetic strength training and isotonic power training with augmented eccentric load, controlled by a computerized robotic engine system. FSPT used free weights. The training volume (sum of repetitions x kg) was similar between all three groups. Vertical jumping capabilities were assessed by countermovement jump (CMJ), squat jump (SJ), drop jump (DJ), and loaded CMJs (10-80 kg). Sprinting capacity was assessed in a 30 m sprint. Secondary variables were squat 1-repetitionmaximum, body composition and quadriceps thickness and architecture. Results: OWL resulted in trivial improvements, and inferior gains compared to FSPT and MSPT for CMJ, SJ, and DJ. MSPT demonstrated small, but robust effects on SJ, DJ and loaded CMJs (3-12%). MSPT was superior to FSPT in improving 30 m sprint performance. FSPT and MSPT, but not OWL, demonstrated increased thickness in the vastus lateralis and rectus femoris (4-7%). Conclusion: MSPT was time-efficient and equally or more effective than FSPT training in improving vertical jumping and sprinting performance. OWL was generally ineffective and inferior to the two other interventions.

• Helland, Christian; Bojsen-Møller, Jens; Raastad, Truls; Seynnes, Olivier R.; Moltubakk, Marie M. & Jakobsen, Vidar Eivind [Vis alle 8 forfattere av denne artikkelen] (2013). Mechanical properties of the patellar tendon in elite volleyball players with and without patellar tendinopathy. British Journal of Sports Medicine. ISSN 0306-3674. 47(13), s. 862–868. doi: 10.1136/bjsports-2013-092275. Vis sammendrag

  Background: Although differences in mechanical properties between symptomatic and healthy tendons have been observed for the Achilles tendon, the impact of tendinopathy on patellar tendon mechanics is not fully documented. The aim of the present case–control study was to assess the mechanical properties of the tendon and jump performance in elite athletes with and without patellar tendinopathy. Methods: We identified 17 male volleyball players with patellar tendinopathy and 18 healthy matched controls from a 5-year prospective cohort study on junior elite volleyball players. Outcome variables included three measures of maximal vertical jump performance and ultrasound-based assessments of patellar tendon cross-sectional area, stiffness and Young's modulus. Results: The proximal cross-sectional area of the patellar tendon was significantly larger in the tendinopathic group (133±11 vs 112±9 mm2, respectively; p<0.001). Pathological tendons presented lower stiffness (2254±280 vs 2826±603 N/mm, respectively; p=0.006) and Young's modulus (0.99±0.16 vs 1.17±0.25 GPa, respectively; p=0.04) than healthy tendons. However, the difference between the countermovement jump height and the squat jump height (3.4±2.2 vs 1.2±1.5 cm, p=0.005) was significantly higher in the tendinopathic group compared with the control group. Conclusions: Patellar tendinopathy is associated with a decrease in the mechanical and material properties of the tendon in elite athletes subjected to a high volume of jumping activity. However, compared with their healthy counterparts, tendinopathic volleyball players have a better ability to utilise the stretch-shortening cycle when jumping.

• Seynnes, Olivier R.; Kamandulis, Sigitas; Kairaitis, Ramutis; Helland, Christian; Campbell, Emma-Louise & Brazaitis, Marius [Vis alle 8 forfattere av denne artikkelen] (2013). Effect of Androgenic-Anabolic Steroids and Heavy Strength Training on Patellar Tendon Morphological and Mechanical Properties. Journal of applied physiology. ISSN 8750-7587. 115(1), s. 84–89. doi: 10.1152/japplphysiol.01417.2012. Vis sammendrag

  Combined androgenic-anabolic steroids (AAS) and overloading affects tendon collagen metabolism and ultrastructure, and is often associated with a higher risk of injury. The aim of this prospective study was to investigate whether such effects would be reflected in the patellar tendon properties of individuals with a history of long-term resistance training and AAS abuse (RTS group), when compared to trained (RT) and untrained (CTRL) non-steroids users. Tendon cross-sectional area (CSA), stiffness, Young's modulus and toe-limit strain were measured in vivo, from synchronized ultrasonography and dynamometry data. The patellar tendon of RT and RTS subjects was much stiffer and larger than in the CTRL group. However, stiffness and modulus were higher in the RTS group (26%, P < 0.05 and 30%, P < 0.01, respectively) than in the RT group. Conversely, tendon CSA was 15% (P < 0.05) larger in the RT group than in RTS, although differences disappeared when this variable was normalized to quadriceps maximal isometric torque. Yet maximal tendon stress was higher in RTS than in RT (15%, P < 0.05), without any statistical difference in maximal strain and toe limit strain between groups. The present lack of difference in toe-limit strain does not substantiate the hypothesis of changes in collagen crimp pattern associated with AAS abuse. However, these findings indicate that tendon adaptations from years of heavy resistance training are different in AAS users, suggesting differences in collagen remodelling. Some of these adaptations (e.g. higher stress) could be linked to a higher risk of tendon injury.

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• Solstad, Tom Erik Jorung; Shaw, Matthew Peter & Helland, Christian (2020). Episode 33 - Styrketreningsmodaliteter del 1 og del 2. [Internett]. Idrettsforskning.
• Lindberg, Kolbjørn; Solberg, Paul Andre; Bjørnsen, Thomas; Helland, Christian; Rønnestad, Bent & Frank, Martin [Vis alle 10 forfattere av denne artikkelen] (2020). FORCE-VELOCITY PROFILING IN ELITE ATHLETES: RELIABILITY AND AGREEMENT BETWEEN METHODS.
• Helland, Christian; Haugen, Tommy; Rakovic, Elvir; Eriksrud, Ola; Seynnes, Olivier R. & Mero, Antti A. [Vis alle 7 forfattere av denne artikkelen] (2019). Correction to: Force–velocity profiling of sprinting athletes: single-run vs. multiple-run methods (European Journal of Applied Physiology, (2019), 119, 2, (465-473), 10.1007/s00421-018-4045-2). European Journal of Applied Physiology. ISSN 1439-6319. 119(2). doi: 10.1007/s00421-018-04057-7.

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