Bjørn Harald Olstad

• Keller, Sebastian; Olstad, Bjørn Harald & Wahl, Patrick (2024). Lower and upper extremity contributions to propulsion and resistance during semi-tethered load-velocity profiling in front crawl swimming. Journal of Sports Sciences. ISSN 0264-0414. doi: 10.1080/02640414.2024.2326347.
• Ljødal, Ingeborg; Olstad, Bjørn Harald & Pensgaard, Anne Marte (2023). Motives, Motivation, and Motivational Climate of Young Norwegian Swimmers, and their Parents’ Belief. Scandinavian Sport Studies Forum. ISSN 2000-088X. 14, s. 151–175. Fulltekst i vitenarkiv Vis sammendrag

  Motivation is important for enjoyment, skill development, and persistence in swimming. The quality and direction of motivation is influenced by a swimmer’s perceived motivational climate, which is created by coaches and parents. The theoretical framework combines self-determination theory and achievement goal theory, to analyse the motives and motivation of swimmers and the influence of social climate on their motivation. Parents greatly impact young children’s participation motives and motivation, but few studies ask parents about their beliefs about their child’s motives and motivation. Online questionnaires were distributed to 11-13-year-old swimmers and their parents. The children responded to five questionnaires measuring sport participation motives, self-determined motivation, goal orientation, coach-initiated motivational climate, and parent-initiated motivational climate. Parents responded to the first two indicating their belief in their child’s motives and self-determined motivation. Results showed that swimmers are predominantly intrinsically motivated, task oriented, and perceive a mastery climate from coaches and parents. Parent’s belief of their child’s motives and self-determined motivation matched the swimmers’ self-reported motives and self-determined motivation. Coaches are shown to impact self-determined motivation and goal orientations to a greater extent than parents. In conclusion, coaches and parents should aim to maintain their current focus on mastery and enjoyment. This can ensure longer participation in and greater enjoyment of the sport, which would lead to further development and improved performance.

• Wettengl, Christina; Karlsson, Rebecca Vilde Martine Krohn; Olstad, Bjørn Harald & Gonjo, Tomohiro (2023). Load-Velocity Profile and Active Drag in Young Female Swimmers: An Age-Group Comparison. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 19(1), s. 44–52. doi: 10.1123/ijspp.2022-0213. Fulltekst i vitenarkiv
• Szczepan, Stefan; Wróblewska, Zofia; Klich, Sebastian; Michalik, Kamil; Gonjo, Tomohiro & Olstad, Bjørn Harald [Vis alle 7 forfattere av denne artikkelen] (2023). Reliability of a semi-tethered front crawl sprint performance test in adolescent swimmers. Frontiers in Physiology. ISSN 1664-042X. 14. doi: 10.3389/fphys.2023.1260346. Fulltekst i vitenarkiv
• Barbosa, Augusto C.; Araújo, Leonardo Tomasello; Leis, Leonardo Vecchi; Lourenço, Thiago Fernando; Barroso, Renato & Gonjo, Tomohiro [Vis alle 9 forfattere av denne artikkelen] (2023). The gold rush in para swimming: changes in the speed curve of a visually impaired world and paralympic champion–a case study. Sports Biomechanics. ISSN 1476-3141. doi: 10.1080/14763141.2023.2221680. Vis sammendrag

  This case study examined the association between 50 m freestyle and speed curve parameters of a world-class Paralympic swimmer and analysed the changes in speed curves and their frequency components across her performance levels. From 2018 to 2021, a visually impaired female swimmer (26.59 s in 50 m freestyle, S12 class) underwent 22 tests to obtain instantaneous speed synchronised with video recording. She regularly performed 50 m freestyle in competitions and time trials. The fast Fourier transformation method converted the speed signal into frequency domains and determined the relative contribution of the harmonics with two maxima and minima (H2, arms actions) and six maxima and minima (H6, legs actions). The functional paired t-test compared the speed curves at the beginning (PRE) and end (POST) of the analysed period. The 50 m freestyle time correlated with average speed (r = −0.50, p = 0.02). The contribution of H6 increased in the first year and remained large, whereas the contribution of H2 was lower throughout the whole period. POST was faster than PRE in five moments that coincide with the downward leg kick moments. These changes allowed her to stay longer at the upper part of the curve and improve performance over time.

• Gonjo, Tomohiro; Olstad, Bjørn Harald; Štastný, Jan; Conceição, Ana & Seifert, Ludovic (2023). Intra- and inter-individual variability in the underwater pull-out technique in 200 m breaststroke turns. PLOS ONE. ISSN 1932-6203. 18(3). doi: 10.1371/journal.pone.0283234. Fulltekst i vitenarkiv Vis sammendrag

  The purpose of the present study was to investigate the intra- and inter-individual variability in arm-leg coordination during the underwater phase of the turn segment in 200 m breaststroke. Thirteen male swimmers were recruited and performed a 200 m breaststroke in a pre-calibrated 25 m pool. Sub-phases during the underwater segment were obtained using a notational analysis, and the mean velocity, displacement and duration during each sub-phase were obtained. A hierarchical cluster analysis (HCA) was performed using the analysed variables in all phases to identify inter-individual variability and random intra-individual variability. In addition, a linear mixed model (LMM: lap as a fixed effect and the participant as a random effect) was conducted to investigate systematic intra-individual variability. HCA identified three coordination patterns that were distinguished by the timing of the dolphin kick relative to the arm pull-out and the duration of the glide with arms at the side. All swimmers except one performed the arm pull-out after the dolphin kick. Nine swimmers maintained one coordination pattern, but other swimmers switched their coordination during the trial, particularly by shortening the duration of the glide with arms at the side. LMM showed a linear decrease (from the first to the last turn) in the time gap between the end of the dolphin kick and the start of the arm pull-out (a glide with the streamlined body position; F = 9.64, p = 0.034) and the glide duration with the arms at the side (F = 11.66, p = 0.015). In conclusion, both inter- and intra-individual variabilities during the underwater phase were evident in 200 m breaststroke turns, which were categorised into three patterns based on the timing of the dolphin kick and the duration of glides.

• Gonjo, Tomohiro; Polach, Marek; Olstad, Bjørn Harald; Romann, Michael & Born, Dennis-Peter (2022). Differences in Race Characteristics between World-Class Individual-Medley and Stroke-Specialist Swimmers. International Journal of Environmental Research and Public Health (IJERPH). ISSN 1661-7827. 19(20). doi: 10.3390/ijerph192013578. Fulltekst i vitenarkiv Vis sammendrag

  The purpose of the present study was to investigate differences between world-class individual medley (IM) swimmers and stroke-specialists using race analyses. A total of eighty 200 m races (8 finalists × 2 sexes × 5 events) at the 2021 European long-course swimming championships were analysed. Eight digital video cameras recorded the races, and the video footage was manually analysed to obtain underwater distance, underwater time, and underwater speed, as well as clean-swimming speed, stroke rate, and distance per stroke. Each lap of the IM races was compared with the first, second, third, and fourth laps of butterfly, backstroke, breaststroke, and freestyle races, respectively. Differences between IM swimmers and specialists in each analysed variable were assessed using an independent-sample t-test, and the effects of sex and stroke on the differences were analysed using a two-way analysis of variance with relative values (IM swimmers’ score relative to the mean specialists’ score) as dependent variables. Breaststroke specialists showed faster clean-swimming speed and longer distance per stroke than IM swimmers for both males (clean-swimming speed: p = 0.011; distance per stroke: p = 0.023) and females (clean-swimming speed: p = 0.003; distance per stroke: p = 0.036). For backstroke and front crawl, specialists exhibited faster underwater speeds than IM swimmers (all p < 0.001). Females showed faster relative speeds during butterfly clean-swimming segments (p < 0.001) and breaststroke underwater segments than males (p = 0.028). IM swimmers should focus especially on breaststroke training, particularly aiming to improve their distance per stroke.

• Born, Dennis-Peter; Schönfelder, Michel; Logan, Oliver; Olstad, Bjørn Harald & Romann, Michael (2022). Performance Development of European Swimmers Across the Olympic Cycle. Frontiers in Sports and Active Living. ISSN 2624-9367. 4. doi: 10.3389/fspor.2022.894066. Fulltekst i vitenarkiv Vis sammendrag

  The aims of the study were to (1) quantify the performance development of race times and key performance indicators of European swimmers across the last Olympic cycle (from 2016 to 2021) and (2) provide reference values for long-course swimming pool events for both sexes from 50 m to 1,500 m including butterfly, backstroke, breaststroke, freestyle, and individual medley. Individual events from the 2016 and 2021 European swimming championships were included. Specifically, 246 men (age: 24.2 ± 3.4 years, FINA points: 890 ± 40) and 256 women races (age: 24.2 ± 4, FINA points: 879 ± 38) of the finalists were recorded and key performance indicators and split times analyzed. Performance differences in finalists of the 2016 and 2021 European championships were determined by an independent t-test and Cohen's d effect size. Reference values were retrieved from 2021 European championship finalists and are provided for all key performance indicators. Race times improved significantly (P < 0.05) or showed moderate (d = 0.5–1) to large effect sizes (d > 1) in 14 (men) and 6 (women) out of 16 events. Improvements were primarily evident in 100 m and 200 m events for males, as well as BR and sprint events for female swimmers. While start times improved in 15 (men) and 14 (women) events, turn times remained inconclusive in both sexes. Generally, breakout distances increased. Clean swimming velocities were faster in 12 (men) and 5 (women) events. In particular, for alternating swimming strokes, i.e., backstroke and freestyle, effect sizes indicated improved swimming efficiency with an inverse relationship between reduced stroke rate and increased distance per stroke. Coaches and performance analysts may use the present reference values as comparative data for race analyses and to specifically prepare swimmers for the various race sections. Data on the performance development should be used to analyze swimmers' potential and set goals for the various events and the next Olympic cycle.

• Gonjo, Tomohiro & Olstad, Bjørn Harald (2022). Reliability of the active drag assessment using an isotonic resisted sprint protocol in human swimming. Scientific Reports. ISSN 2045-2322. 12. doi: 10.1038/s41598-022-17415-5. Fulltekst i vitenarkiv Vis sammendrag

  The purpose of the presents study was to investigate the reliability of the active drag (Da) assessment using the velocity perturbation method (VPM) with different external resisted forces. Eight male and eight female swimmers performed 25 m sprints with five isotonic loads (1–2–3–4–5 kg for females; 1–3–5–7–9 kg for males), which were repeated twice on different days. The mean velocity and semi-tethered force were computed for each condition, and the free-swimming maximum velocity was estimated with load-velocity profiling. From the obtained variables, Da at the maximum free-swimming condition was calculated using VPM. Absolute and typical errors and the intra-class correlation (ICC) were calculated to assess test–retest reliability. 95% confidence interval (95% CI) lower bound of ICC was larger than 0.75 in 3, 4 (females only) and 5 kg trials in both sexes (corresponding to 37–60 N additional resistance; all p < 0.001), which also showed small absolute and relative typical errors (≤ 2.7 N and ≤ 4.4%). In both sexes, 1 kg load trial (16–17 N additional resistance) showed the lowest reliability (95% CI of ICC; − 0.25–0.83 in males and 0.07–0.94 in females). These results suggested that a tethered force of 37–60 N should be used to assess Da using VPM.

• Barbosa, Augusto C.; Barroso, Renato; Gonjo, Tomohiro; Rossi, Marcel M.; Paolucci, Leopoldo A. & Olstad, Bjørn Harald [Vis alle 7 forfattere av denne artikkelen] (2021). 50 m freestyle in 21, 22 and 23 s: What differentiates the speed curve of world-class and elite male swimmers? International Journal of Performance Analysis in Sport. ISSN 2474-8668. doi: 10.1080/24748668.2021.1971509. Fulltekst i vitenarkiv Vis sammendrag

  We examined the association between 50 m freestyle performance (50FS) and average speed (AS), peak speed (PS), minimum speed (MS) and intracyclic speed variation (ISV) and compared the speed curves from swimmers with different performance levels using functional analysis of variance (FANOVA). Fourteen male swimmers (50FS: 22.50 ± 0.58 s) performed a maximal sprint with a speedometer and AS, PS, MS, and IVV were assessed for correlational analysis. 50FS were obtained in official competitions. Swimmers were assigned to three groups based on actual 50FS: G21 (n = 2, 21.99 ± 0.04 s), G22 (n = 6, 22.82 ± 0.10 s) or G23 (n = 6, 23.55 ± 0.18 s). FANOVA compared the average curves. 50FS correlated to AS (r = −0.781, p = 0.001) and PS (ρ = −0.766, p = 0.001), but not to MS (r = −0.185, p = 0.527) or IVV (r = −0.323, p = 0.259). FANOVA showed that faster swimmers achieved higher PS and stayed longer at the upper part of the curve. 50FS performance is related to average and peak speed assessed with the speedometer. Swimmers should seek techniques to maintain the speed at the upper part of the curve as long as possible.

• Olstad, Bjørn Harald; Gonjo, Tomohiro; Conceição, Ana; Šťastný, Jan & Seifert, Ludovic (2021). Arm–leg coordination during the underwater pull-out sequence in the 50, 100 and 200 m breaststroke start. Journal of Science and Medicine in Sport. ISSN 1440-2440. doi: 10.1016/j.jsams.2021.08.006. Fulltekst i vitenarkiv Vis sammendrag

  Objectives: To investigate the arm–leg coordination from different perspectives of motor control during the underwater start sequence to understand whether differences exist between the three competitive breaststroke swimming events. Design: Cross-sectional study. Methods: Forty-one breaststroke races (with race times relative to the world record): 50-meter (n = 14, 87.6%), 100-meter (n = 14, 88.5%) and 200-meter (n = 13, 85.4%) were recorded. A race analysis system tracked the two-dimensional displacement of the head. Key points from the underwater start sequence were obtained from notational analysis in order to compute seven time-gaps and four phases to assess the arm–leg coordination and timing of the dolphin kick. A one-way ANOVA with Bonferroni post-hoc correction was used to assess differences between the time gaps and phases for the three events. Results: Differences between the three events were found for total underwater glide, and the first (T0) and second (T1) major glide phase. No differences between the events were found in relative duration and distance for the time gaps related to arm–leg coordination (T1–3, T4, T6) and timing of the dolphin kick (T4–5) during the underwater start sequence. Conclusions: The arm–leg coordination and timing of the dolphin kick showed no difference between the events, but the total underwater glide duration was longer in both the 100- and 200-meter compared with the 50-meter start. This shows that swimmers did not change the complex inter-limb coordination between the competitive events, but only modified the least complex movement, gliding, to adapt to the swimming speed of the respective events.

• Gonjo, Tomohiro & Olstad, Bjørn Harald (2021). Differences between elite and sub-elite swimmers in a 100 m breaststroke: a new race analysis approach with time-series velocity data. Sports Biomechanics. ISSN 1476-3141. doi: 10.1080/14763141.2021.1954238. Fulltekst i vitenarkiv Vis sammendrag

  The purpose of the present study was to investigate differences in a 100 m breaststroke time-trial between elite and sub-elite swimmers. Elite and sub-elite male swimmers (seven each; 772.1 ± 35.2 and 610.6 ± 24.7 FINA point, respectively) performed 100 m breaststroke, which was recorded by a multi-camera system that provided the mean and time-series velocity data in the glide, pull-out, and clean-swimming segments. The mean velocity in each segment was compared between the groups using an independent-samples t-test (for the 1st lap) and two-way mixed-design ANOVA (for the 2nd—4th laps), which suggested a larger mean clean-swimming (in all laps; 7–11% difference) and glide (in the 2nd and 3rd lap; about 13% difference) velocity for the elite swimmers. The time-series data displayed faster velocity in elite swimmers than in the sub-elite group during the first part (up to 40% time) of the glide segment (p < 0.05). Differences in the clean-swimming segment between the groups were observed (p < 0.001) apart from the first 5–15% time of the segment. No differences in the pull-out and at the beginning of the clean-swimming imply that coaches and swimmers should not assume that a good clean-swimming technique also guarantees fast velocity in these segments.

• Seifert, Ludovic; Conceição, Ana; Gonjo, Tomohiro; Stastny, Jan & Olstad, Bjørn Harald (2021). Arm–Leg coordination profiling during the dolphin kick and the arm pull-out in elite breaststrokers. Journal of Sports Sciences. ISSN 0264-0414. doi: 10.1080/02640414.2021.1950446. Fulltekst i vitenarkiv Vis sammendrag

  In breaststroke races, the dolphin kick could finish before, at the same time, or during the arm pull-out, but it is unclear how swimmers perform this technique. The aim of this study was to investigate whether swimmers glide between the dolphin kick and arm pull-out, favour continuity or even overlap those two phases, as it would impact the active underwater sequence. Fourteen international and national male swimmers performed 100-m breaststroke with all-out effort in a pre-calibrated 25 m swimming pool. A multi-camera system tracked the head of the swimmers. Key points of the active underwater sequence were obtained from notational analysis. A hierarchical cluster analysis identified three coordination profiles. All swimmers started their dolphin kick before the arm pull-out. However, one swimmer started the arm pull-out before the end of the dolphin kick, seven swimmers started the arm pull-out after the end of the dolphin kick, and four swimmers synchronised the beginning of the arm pull-out and the end of the dolphin kick, while two other swimmers mixed two coordination profiles among the start and the three turns. Those different profiles allow achieving similar performance outcome, suggesting individual training regarding the underwater phase.

• Gonjo, Tomohiro; Njøs, Nikolai; Eriksrud, Ola & Olstad, Bjørn Harald (2021). The Relationship Between Selected Load-Velocity Profile Parameters and 50 m Front Crawl Swimming Performance. Frontiers in Physiology. ISSN 1664-042X. 12. doi: 10.3389/fphys.2021.625411. Fulltekst i vitenarkiv Vis sammendrag

  The purpose of the present study was to establish relationships between sprint front crawl performance and a swimming load-velocity profile. Fourteen male national-level swimmers performed 50 m front crawl and semi-tethered swimming with three progressive loads. The 50 m performance was recorded with a multi-camera system, with which two-dimensional head displacement and the beginning of each arm-stroke motion were quantified. Forward velocity (V50m), stroke length (SL) and frequency (SF) were quantified for each cycle, and the mean value of all cycles, excluding the first and last cycles, was used for the analysis. From the semi-tethered swimming test, the mean velocity during three stroke cycles in mid-pool was calculated and plotted as a function of the external load, and a linear regression line expressing the relationship between the load and velocity was established for each swimmer. The intercepts between the established line and the axes of the plot were defined as theoretical maximum velocity (V0) and load (L0). Large to very large correlations were observed between V50m and all variables derived from the load-velocity profiling; L0 (R = 0.632, p = 0.015), L0 normalized by body mass (R = 0.743, p = 0.002), V0 (R = 0.698, p = 0.006), and the slope (R = 0.541, p < 0.046). No significant relationships of SL and SL with V50m and the load-velocity variables were observed, suggesting that each swimmer has his own strategy to achieve the highest swimming velocity. The findings suggest that load-velocity profiling can be used to assess swimming-specific strength and velocity capabilities related to sprint front crawl performance.

• Reichmuth, Daniela; Olstad, Bjørn Harald & Born, Dennis-Peter (2021). Key performance indicators related to strength, endurance, flexibility, anthropometrics, and swimming performance for competitive aquatic lifesaving. International Journal of Environmental Research and Public Health (IJERPH). ISSN 1661-7827. 18(7). doi: 10.3390/ijerph18073454. Fulltekst i vitenarkiv Vis sammendrag

  The aim of the study was to investigate key performance indicators for the individual pool-based disciplines of competitive lifesaving regarding strength, flexibility, sprint and endurance swimming performance, anthropometric characteristics, and technical skills specific to competitive lifesaving. Data were collected from Swiss national team members (seven males: age 19 ± 2 yrs, body mass 77 ± 11 kg, body height 177 ± 7 cm and seven females age 21 ± 5 yrs, body mass 64 ± 6 kg, body height 171 ± 4 cm) competing at the 2019 European lifesaving championships. Potential key performance indicators were assessed with race times derived from the 2019 long-course season using Spearman’s correlation coefficient. Large and significant correlations showed that sprint, i.e., 50 m freestyle performance (r ≥ 0.770), was related to race time of all pool-based disciplines, rather than endurance swimming performance. Additionally, significant correlations revealed upper body strength, i.e., bench press (r ≥ −0.644) and pull (r ≥ −0.697), and leg strength (r ≥ −0.627) as key performance indicators. Importance of the lifesaving-specific skills, anthropometric characteristics, and core strength varied between the disciplines. Flexibility was not significantly related to race times of competitive lifesaving. The present study showed that sprint swimming performance, upper body, and leg strength are particularly important for competitive lifesaving. As other physical and technical requirements varied between the pool-based disciplines, coaches may use the present key performance indicators to establish training guidelines and conditioning programs as well as prioritize skill acquisition in training to specifically prepare athletes for their main disciplines.

• Barbosa, Augusto C.; Barroso, Renato; Olstad, Bjørn Harald & Andrade, André G. (2021). Long-term changes in the speed curve of a world-class butterfly swimmer. Journal of Sports Medicine and Physical Fitness. ISSN 0022-4707. 61(1), s. 152–158. doi: 10.23736/S0022-4707.20.11557-3. Fulltekst i vitenarkiv Vis sammendrag

  This study describes the changes in selected points of the speed curve, stroke rate (SR), and stroke length (SL) of an elite butterfly swimmer and examines their relationship with average speed (AS) and competitive performance. Over eight years, a male swimmer (50 and 100 m: 22.70 and 51.47 s) underwent 18 tests to assess AS, SR, SL, intracyclic speed variation (ISV), and eight selected points of the speed curve. Peak1 is the maximum speed in the upward kick executed during the arm recovery; peak2 is the maximum speed in the first downward kick after the arm entered into the water; peak3 is the maximum speed during the arm pull; and peak4 is the maximum speed during the arm push combined with the second downward kick. Min1, min2, min3, min4 corresponds to the minimum speeds found respectively before each peak speed. Official competitive results in 50 (50BF) and 100 m (100BF) within three weeks of the speed tests were registered. SR (r=0.736), ISV (r=-0.493), peak1 (r=0.555), min2 (r=0.558), and min3 (r=0.539) were correlated with AS. 50BF was correlated with AS (r=-0.658) and peak1 (r=-0.820), whereas 100BF with AS (r=-0.676), SR (r=-0.571), peak1 (r=-0.758), and peak2 (r=-0.594). AS increased by improving SR, peak1 and peak3. Increases in min2 and min3 indicate better transitions from resistive to propulsive phases. Selected points of the speed curve may predict butterfly performance.

• Olstad, Bjørn Harald (2021). Helse, miljø og sikkerhet i svømmeog livredningsopplæring. I Gjølme, Egil Galaaen (Red.), Utendørs svømme- og livredningsopplæring. Universitetsforlaget. ISSN 9788215034423. s. 99–126.
• Olstad, Bjørn Harald; Berg, Pernille Ravn & Kjendlie, Per-Ludvik (2020). Outsourcing Swimming Education - Experiences and Challenges. International Journal of Environmental Research and Public Health (IJERPH). ISSN 1661-7827. 18(1). doi: 10.3390/ijerph18010006. Fulltekst i vitenarkiv Vis sammendrag

  In Norway, swimming and lifesaving education (swimming education) is an obligatory part of physical education, with explicit learning aims after grade four. After recent reports of Norwegian pupils achieving low scores in swimming abilities, the Government has outlined strategies for improving swimming education. There is a notable trend toward using external providers in delivering swimming education. This article examines the outsourcing of swimming education in Norwegian primary schools. Eighteen semi-structured interviews were conducted with school leaders, physical education teachers and swimming instructors involved in outsourcing arrangements. The outsourcing was organized through private providers, municipalities, or local swimming clubs. Data were analyzed thematically and separated into highlighted areas of outsourcing practices. The results showed that outsourcing may be a solution for schools that lack staff with swimming experience and knowledge. It also indicates that teacher courses, professional development through collaboration, and strategies for measuring quality would improve swimming education.

• Gonjo, Tomohiro & Olstad, Bjørn Harald (2020). Race Analysis in Competitive Swimming: A Narrative Review. International Journal of Environmental Research and Public Health (IJERPH). ISSN 1661-7827. 18(1). doi: 10.3390/ijerph18010069. Fulltekst i vitenarkiv Vis sammendrag

  Researchers have quantified swimming races for several decades to provide objective information on race strategy and characteristics. The purpose of the present review was to summarize knowledge established in the literature and current issues in swimming race analysis. A systematic search of the literature for the current narrative review was conducted in September 2020 using Web of Science, SPORTDiscus (via EBSCO), and PubMed. After examining 321 studies, 22 articles were included in the current review. Most studies divided the race into the start, clean swimming, turn, and/or finish segments; however, the definition of each segment varied, especially for the turn. Ideal definitions for the start and turn-out seemed to differ depending on the stroke styles and swimmers’ level. Many studies have focused on either 100 m or 200 m events with the four strokes (butterfly, backstroke, breaststroke, and freestyle). Contrastingly, there were few or no studies for 50 m, long-distance, individual medley, and relay events. The number of studies examining races for short course, junior and Paralympic swimmers were also very limited. Future studies should focus on those with limited evidence as well as race analysis outside competitions in which detailed kinematic and physiological analyses are possible.

• Gonjo, Tomohiro & Olstad, Bjørn Harald (2020). Start and turn performances of competitive swimmers in sprint butterfly swimming. Journal of Sports Science and Medicine. ISSN 1303-2968. 19(4), s. 727–734. Fulltekst i vitenarkiv
• Olstad, Bjørn Harald; Wathne, Henrik & Gonjo, Tomohiro (2020). Key Factors Related to Short Course 100 m Breaststroke Performance. International Journal of Environmental Research and Public Health (IJERPH). ISSN 1661-7827. 17(17). doi: 10.3390/ijerph17176257. Fulltekst i vitenarkiv Vis sammendrag

  Background and aim: To identify kinematic variables related to short course 100 m breaststroke performance. Methods: An automatic race analysis system was utilized to obtain start (0–15 m), turn (5 m before the wall until 10 m out), finish (95–100 m), and clean swimming (the rest of the race) segment times as well as cycle rate and cycle length during each swimming cycle from 15 male swimmers during a 100 m breaststroke race. A bivariate correlation and a partial correlation were employed to assess the relationship between each variable and swimming time. Results: Turns were the largest time contributor to the finishing time (44.30 ± 0.58%), followed by clean swimming (38.93 ± 0.50%), start (11.39 ± 0.22%), and finish (5.36 ± 0.18%). The finishing time was correlated (p < 0.001) with start segment time (r = 0.979), clean swimming time (r = 0.940), and 10 m turn-out time (r = 0.829). The clean swimming time was associated with the finishing time, but cycle rate and cycle length were not. In both start and turns, the peak velocity (i.e., take-off and push-off velocity) and the transition velocity were related to the segment time (r ≤ −0.673, p ≤ 0.006). Conclusions: Breaststroke training should focus on: (I) 15 m start with generating high take-off velocity, (II) improving clean swimming velocity by finding an optimal balance between cycle length and rate, (III) 10 m turn-out with maintaining a strong wall push-off, and (IV) establishing a high transition velocity from underwater to surface swimming.

• Olstad, Bjørn Harald; Gonjo, Tomohiro; Njøs, Nikolai; Abächerli, Kathrin & Eriksrud, Ola (2020). Reliability of Load-Velocity Profiling in Front Crawl Swimming. Frontiers in Physiology. ISSN 1664-042X. 11, s. 1–8. doi: 10.3389/fphys.2020.574306. Fulltekst i vitenarkiv Vis sammendrag

  The purposes of this study were to establish test-retest reliability of calculating load-velocity profiles in front crawl swimming using five and three different external loads, and if outcome results were comparable between calculation methods for monitoring performance over time. Fifteen swimmers at either national or international competition level (seven females and eight males) participated in this study. The subjects performed 25 m of semi-tethered swimming with maximal effort with five progressive loads (females 1, 2, 3, 4, and 5 kg and males 1, 3, 5, 7, and 9 kg) as well as 50 m maximal front crawl on 2 different days. The mean velocity during three stroke cycles in mid-pool was calculated and plotted as a function of the external load. Relationship between the load and velocity was expressed by a linear regression line and established for each swimmer. The intercepts between the axes of the plot and the established regression line were defined as theoretical maximum velocity (V0) and load (L0). In addition, L0 was also expressed as a percentage of body mass (rL0). The coefficient of determination (R2) and the slope (Slv) of the linear load-velocity relationship were calculated. The intra-class correlation coefficient (ICC) showed excellent agreement (ICC ≥0.902) for all variables. The coefficient of variation was ≤3.14% and typical error was rated as “good” in all variables. A difference was found between day 1 and 2 in V0 for three- and five-load calculations and for 50 m front crawl time (p < 0.05). No difference was found between the load-velocity profile outcomes variables compared between the three- and five-trial protocols on neither day 1 nor 2. The Bland-Altman plots showed a small bias across all resistance conditions for five loads, L0: 0.04 kg, rL0: 0.13%, V0: −0.03 m/s, and Slv: 0.003 −m/s/kg and for three loads, L0: −0.24 kg, rL0: −0.27%, V0: −0.04 m/s, Slv: 0.002 −m/s/kg. In conclusion, the load-velocity profile for front crawl swimming can be calculated with high reliability from both five and three external loads and comparable results in outcome variables were established. These methods can be used to monitor performance parameters over time, and to investigate and compare swimmers’ velocity and strength capabilities to allow for individualized training prescription to improve performance.

• Olstad, Bjørn Harald & Zinner, Christoph (2020). Validation of the Polar OH1 and M600 optical heart rate sensors during front crawl swim training. PLOS ONE. ISSN 1932-6203. 15(4). doi: 10.1371/journal.pone.0231522. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: The Polar OH1 is an optical heart rate (HR) sensor which can be used on different parts of the body. The purpose of the study was to evaluate the validity of the OH1 as well as a wrist worn heart rate device (Polar M600) during swimming. Methods: Twenty-six well-trained competitive swimmers performed a regular training session including different swimming intensities. During the training the swimmers wore a H10 HR sensor with Polar Pro strap (H10) underneath the swim suit, a Polar OH1 optical HR sensor (OH1) underneath the swimming cap at the temple, and a sports watch with optical HR sensor, Polar M600 smart watch (M600) on the wrist. Results: No difference in HRmax, HRmean and HRmin between H10 and OH1 were evident. The HRmax and HRmean obtained by the M600 was significantly lower than the obtained by H10 and OH1 (p < 0.05). The ICC showed mostly excellent agreements between H10 and OH1 and poor to good agreements between H10 and M600. Bland-Altmann plot for M600 vs. H10 indicates upper and lower limits of agreement of -53.0 to 33.9 beats per minute. For OH1 vs. H10 the upper and lower limits of agreement were -26.9 to 24.7 beats per minute. Conclusion: The Polar OH1 optical HR sensor is a valid tool to monitor HR of different intensities during swimming whereas the Polar M600 smart watch as a wrist worn device is less accurate.

• Gonjo, Tomohiro; Eriksrud, Ola; Papoutsis, Filip Dimitrios Evje & Olstad, Bjørn Harald (2020). Relationships between a Load-velocity Profile and Sprint Performance in Butterfly Swimming. International Journal of Sports Medicine (IJSM). ISSN 0172-4622. 41(7), s. 461–467. doi: 10.1055/a-1103-2114. Vis sammendrag

  The purpose of this study was to establish the relationships between 50 m sprint swimming performance and variables acquired from a swimming load-velocity profile established by semi-tethered butterfly swimming. Twelve male elite swimmers participated in the present study and performed 50 m sprint and semi-tethered butterfly swimming with different loads. The mean velocity among all upper-limb cycles was obtained from the 50 m swimming (race velocity), and maximum load and velocity were predicted from the load-velocity profile established by the semi-tethered swimming test. There was a very large correlation (r=0.885, p<0.01) and a high intra-class correlation (0.844, p<0.001) between the race velocity and the predicted maximum velocity. Significant correlations were also observed between the predicted maximum load and the 50 m time as well as the race velocity (r=− 0.624 and 0.556, respectively, both p<0.05), which imply that an ability to achieve a large tethered swimming force is associated with 50 m butterfly performance. These results indicate that the load-velocity profile is a useful tool for predicting and assessing sprint butterfly swimming performance.

• Kamandulis, Sigitas; Juodsnukis, Antanas; Stanislovaitiene, Jurate; Zuoziene, Ilona Judita; Bogdelis, Andrius & Mickevicius, Mantas [Vis alle 10 forfattere av denne artikkelen] (2020). Daily resting heart rate variability in adolescent swimmers during 11 weeks of training. International Journal of Environmental Research and Public Health (IJERPH). ISSN 1661-7827. 17(6). doi: 10.3390/ijerph17062097. Vis sammendrag

  Adolescent athletes are particularly vulnerable to stress. The current study aimed to monitor one of the most popular and accessible stress markers, heart rate variability (HRV), and its associations with training load and sleep duration in young swimmers during an 11-week training period to evaluate its relevance as a tool for monitoring overtraining. National-level swimmers (n = 22, age 14.3 ± 1.0 years) of sprint and middle distance events followed individually structured training programs prescribed by their swimming coach with the main intention of preparing for the national championships. HRV after awakening, during sleep and training were recorded daily. There was a consistent ~4.5% reduction in HRV after 3–5 consecutive days of high (>6 km/day) swimming volume, and an inverse relationship of HRV with large (>7.0 km/day) shifts in total training load (r = −0.35, p < 0.05). Day-to-day HRV did not significantly correlate with training volume or sleep duration. Taken together, these findings suggest that the value of HRV fluctuations in estimating the balance between the magnitude of a young athlete’s physical load and their tolerance is limited on a day-to-day basis, while under sharply increased or extended training load the lower HRV becomes an important indicator of potential overtraining.

• Felix, Eduardo Ramos; da Silva, Hugo Plácido; Olstad, Bjørn Harald; Cabri, Jan Maria Hendrick & Correia, Paulo Lobato (2019). SwimBIT: A novel approach to stroke analysis during swim training based on attitude and heading reference system (AHRS). Sports. ISSN 2075-4663. 7(11). doi: 10.3390/sports7110238. Fulltekst i vitenarkiv Vis sammendrag

  In a world where technology is assuming a pervasive role, sports sciences are also increasingly exploiting the possibilities opened by advanced sensors and intelligent algorithms. This paper focuses on the development of a convenient, practical, and low-cost system, SwimBIT, which is intended to help swimmers and coaches in performance evaluation, improvement, and injury reduction. Real-world data were collected from 13 triathletes (age 20.8 ± 3.5 years, height 173.7 ± 5.3 cm, and weight 63.5 ± 6.3 kg) with different skill levels in performing the four competitive styles of swimming in order to develop a representative database and allow assessment of the system’s performance in swimming conditions. The hardware collects a set of signals from swimmers based on an attitude and heading reference system (AHRS), and a machine learning workflow for data analysis is used to extract a selection of indicators that allows analysis of a swimmer’s performance. Based on the AHRS data, three novel indicators are proposed: trunk elevation, body balance, and body rotation. Experimental evaluation has shown promising results, with a 100% accuracy in swim lap segmentation, a precision of 100% in the recognition of backstroke, and a precision of 89.60% in the three remaining swimming techniques (butterfly, breaststroke, and front crawl). The performance indicators proposed here provide valuable information for both swimmers and coaches in their quest for enhancing performance and preventing injuries.

• Olstad, Bjørn Harald; Bjørlykke, Veronica O. & Olstad, Daniela Schäfer (2019). Maximal heart rate for swimmers. Sports. ISSN 2075-4663. 7(11). doi: 10.3390/sports7110235. Fulltekst i vitenarkiv Vis sammendrag

  The main purpose of this study was to identify whether a different protocol to achieve maximal heart rate should be used in sprinters when compared to middle-distance swimmers. As incorporating running training into swim training is gaining increased popularity, a secondary aim was to determine the difference in maximal heart rate between front crawl swimming and running among elite swimmers. Twelve elite swimmers (4 female and 8 male, 7 sprinters and 5 middle-distance, age 18.8 years and body mass index 22.9 kg/m2) swam three different maximal heart rate protocols using a 50 m, 100 m and 200 m step-test protocol followed by a maximal heart rate test in running. There were no differences in maximal heart rate between sprinters and middle-distance swimmers in each of the swimming protocols or between land and water (all p ≥ 0.05). There were no significant differences in maximal heart rate beats-per-minute (bpm) between the 200 m (mean ± SD; 192.0 ± 6.9 bpm), 100 m (190.8 ± 8.3 bpm) or 50 m protocol (191.9 ± 8.4 bpm). Maximal heart rate was 6.7 ± 5.3 bpm lower for swimming compared to running (199.9 ± 8.9 bpm for running; p = 0.015). We conclude that all reported step-test protocols were suitable for achieving maximal heart rate during front crawl swimming and suggest that no separate protocol is needed for swimmers specialized on sprint or middle-distance. Further, we suggest conducting sport-specific maximal heart rate tests for different sports that are targeted to improve the aerobic capacity among the elite swimmers of today.

• Olstad, Bjørn Harald; Vaz, Joao Rocha; Zinner, Christoph; Cabri, Jan Maria Hendrick & Kjendlie, Per-Ludvik (2017). Muscle coordination, activation and kinematics of world-class and elite breaststroke swimmers during submaximal and maximal efforts. Journal of Sports Sciences. ISSN 0264-0414. 35(11), s. 1107–1117. doi: 10.1080/02640414.2016.1211306. Vis sammendrag

  The aims of this study were to describe muscular activation patterns and kinematic variables during the complete stroke cycle (SC) and the different phases of breaststroke swimming at submaximal and maximal efforts. Surface electromyography (sEMG) was collected from eight muscles in nine elite swimmers; five females (age 20.3 ± 5.4 years; Fédération Internationale de Natation [FINA] points 815 ± 160) and four males (27.7 ± 7.1 years; FINA points 879 ± 151). Underwater cameras were used for 3D kinematic analysis with automatic motion tracking. The participants swam 25 m of breaststroke at 60%, 80% and 100% effort and each SC was divided into three phases: knee extension, knee extended and knee flexion. With increasing effort, the swimmers decreased their SC distance and increased their velocity and stroke rate. A decrease during the different phases was found for duration during knee extended and knee flexion, distance during knee extended and knee angle at the beginning of knee extension with increasing effort. Velocity increased for all phases. The mean activation pattern remained similar across the different effort levels, but the muscles showed longer activation periods relative to the SC and increased integrated sEMG (except trapezius) with increasing effort. The muscle activation patterns, muscular participation and kinematics assessed in this study with elite breaststroke swimmers contribute to a better understanding of the stroke and what occurs at different effort levels. This could be used as a reference for optimising breaststroke training to improve performance.

• Olstad, Bjørn Harald; Zinner, Christoph; Vaz, Joao Rocha; Cabri, Jan Maria Hendrick & Kjendlie, Per-Ludvik (2016). Muscle Activation in World Champions, World-Class and National Breaststroke Swimmers. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 12(4), s. 538–547. doi: 10.1123/ijspp.2015-0703. Vis sammendrag

  Purpose: Investigating the muscle activation patterns and coactivation with the support of kinematics in some of the world’s best breaststrokers and identify performance discriminates related to national elites at maximal effort. Methods: Surface electromyography was collected in eight muscles from four world-class (including two world champions) and four national elite breaststroke swimmers during a 25 m of breaststroke at maximal effort. Results: World-class spent less time during the leg recovery (p = .043), began this phase with a smaller knee angle (154.6° vs 161.8°) and had a higher median velocity of 0.18 m/s during the leg glide compared to national elites. Compared to national elites, world-class swimmers showed a difference in the muscular activation patterns for all eight muscles. In leg propulsion phase; less triceps brachii activation (one swimmer 6% vs median 23.0% (8.8)). In leg glide phase; activation in rectus femoris and gastrocnemius during the beginning of this phase (all world-class vs only one national elite), a longer activation in pectoralis major (world champions 71% (0.5) vs 50.0 (4.3)) (propulsive phase of the arms). In leg recovery phase; more activation in biceps femoris (50.0% (15.0) vs 20.0% (14.0)), and a later and quicker activation in tibialis anterior (40.0% (7.8) vs 52.0% (6.0)). In the stroke cycle; no coactivation in tibialis anterior and gastrocnemius for world champions. Conclusion: These components are important performance discriminants. They can be used for improving muscular activation patterns and kinematics through the different breaststroke phases. Further, they can also be used as focus points for learning breaststroke to beginners.

• Vaz, Joao Rocha; Olstad, Bjørn Harald; Cabri, Jan Maria Hendrick; Kjendlie, Per-Ludvik; Pezarat-Correia, Pedro & Hug, Francois (2016). Muscle coordination during breaststroke swimming: Comparison between elite swimmers and beginners. Journal of Sports Sciences. ISSN 0264-0414. 34(20), s. 1941–1948. doi: 10.1080/02640414.2016.1143109. Vis sammendrag

  The present study aimed to compare muscle coordination strategies of the upper and lower limb muscles between beginners and elite breaststroke swimmers. Surface electromyography (EMG) of eight muscles was recorded in 16 swimmers (8 elite, 8 beginners) during a 25 m swimming breaststroke at 100% of maximal effort. A decomposition algorithm was used to identify the muscle synergies that represent the temporal and spatial organisation of muscle coordination. Between-groups indices of similarity and lag times were calculated. Individual muscle patterns were moderately to highly similar between groups (between-group indices range: 0.61 to 0.84). Significant differences were found in terms of lag time for pectoralis major (P < 0.05), biceps brachii, rectus femoris and tibialis anterior (P < 0.01), indicating an earlier activation for these muscles in beginners compared to elites (range: −13.2 to −3.8% of the swimming cycle). Three muscle synergies were identified for both beginners and elites. Although their composition was similar between populations, the third synergy exhibited a high within-group variability. Moderate to high indices of similarity were found for the shape of synergy activation coefficients (range: 0.63 to 0.88) but there was a significant backward shift (−8.4% of the swimming cycle) in synergy #2 for beginners compared to elites. This time shift suggested differences in the global arm-to-leg coordination. These results indicate that the synergistic organisation of muscle coordination during breaststroke swimming is not profoundly affected by expertise. However, specific timing adjustments were observed between lower and upper limbs.

• Olstad, Bjørn Harald; Grydeland, May; Vaz, Joao Rocha; Zinner, Christoph; Cabri, Jan Maria Hendrick & Kjendlie, Per-Ludvik (2015). Muscle Activation of World-Class Breaststroke Swimmers. I Radmann, Aage; Hedenborg, S & Tsolakidis, E (Red.), 20th annual Congress of the EUROPEAN COLLEGE OF SPORT SCIENCE 24th - 27th June 2015, Malmö – Sweden BOOK OF ABSTRACTS. European College of Sport Science. ISSN 978-91-7104-567-6. s. 469–469. doi: 10.1123/ijspp.2015-0703.
• Guignard, Brice; Olstad, Bjørn Harald; Escobar, David Simbaña; Lauer, Jessy; Kjendlie, Per-Ludvik & Rouard, Annie H. (2015). Different muscle-recruitment strategies among elite breaststrokers. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 10(8), s. 1061–1065. doi: 10.1123/ijspp.2014-0498. Vis sammendrag

  Purpose: To investigate electromyographical (EMG) profiles characterizing the lower-limb flexion-extension in an aquatic environment in high-level breaststrokers. Methods: The 2-dimensional breaststroke kick of 1 international- and 2 national-level female swimmers was analyzed during 2 maximal 25-m swims. The activities of biceps femoris, rectus femoris, gastrocnemius, and tibialis anterior were recorded. Results: The breaststroke kick was divided in 3 phases, according to the movements performed in the sagittal plane: push phase (PP) covering 27% of the total kick duration, glide phase (GP) 41%, and recovery phase (RP) 32%. Intrasubject reproducibility of the EMG and kinematics was observed from 1 stroke cycle to another. In addition, important intersubject kinematic reproducibility was noted, whereas muscle activities discriminated the subjects: The explosive PP was characterized by important muscle-activation peaks. During the recovery, muscles were likewise solicited for swimmers 1 (S1) and 2 (S2), while the lowest activities were observed during GP for S2 and swimmer 3 (S3), but not for S1, who maintained major muscle solicitations. Conclusions: The main muscle activities were observed during PP to perform powerful lower-limb extension. The most-skilled swimmer (S1) was the only 1 to solicit her muscles during GP to actively reach better streamlining. Important activation peaks during RP correspond to the limbs acting against water drag. Such differences in EMG strategies among an elite group highlight the importance of considering the muscle parameters used to effectively control the intensity of activation among the phases for a more efficient breaststroke kick.

• Lauer, Jessy; Olstad, Bjørn Harald; Minetti, Alberto Enrico; Kjendlie, Per-Ludvik & Rouard, A.H. (2015). Breaststroke swimmers moderate internal work increases toward the highest stroke frequencies. Journal of Biomechanics. ISSN 0021-9290. 48(12), s. 3012–3016. doi: 10.1016/j.jbiomech.2015.07.033.
• Pimentel, Angela; Gomes, Ricardo; Olstad, Bjørn Harald & Gamboa, Hugo (2015). A new tool for the automatic detection of muscular voluntary contractions in the analysis of electromyographic signals. Interacting with computers. ISSN 0953-5438. 27(5), s. 492–499. doi: 10.1093/iwc/iwv008. Vis sammendrag

  Electromyographic (EMG) signals play a key role in many clinical and biomedical applications. They can be used for identifying patients with muscular disabilities, assessing lower-back pain, kinesiology and motor control. There are three common applications of the EMG signal: (1) to determine the activation timing of the muscle; (2) to estimate the force produced by the muscle and (3) to analyze muscular fatigue through analysis of the frequency spectrum of the signal. We have developed an EMG tool that was incorporated in an existing web-based biosignal acquisition and processing framework. This tool can be used on a post-processing environment and provides not only frequency and time parameters, but also an automatic detection of starting and ending times for muscular voluntary contractions using a threshold-based algorithm with the inclusion of the Teager–Kaiser energy operator. The algorithm for the muscular voluntary contraction detection can also be reported after a real-time acquisition, in order to discard possible outliers and simultaneously compare activation times in different muscles. This tool covers all known applications and allows a careful and detailed analysis of the EMG signal for both clinicians and researchers. The detection algorithm works without user interference and is also user-independent. It manages to detect muscular activations in an interactive process. The user simply has to select the signal's time interval as input, and the outcomes are provided afterwards.

• Olstad, Bjørn Harald; Zinner, Christoph; Cabri, Jan Maria Hendrick & Kjendlie, Per-Ludvik (2014). Surface electromyographic measurements on land prior to and after 90 min of submersion (swimming) are highly reliable. Journal of Electromyography & Kinesiology. ISSN 1050-6411. 24(5), s. 698–703. doi: 10.1016/j.jelekin.2014.06.006. Vis sammendrag

  The purpose of this study was to investigate the reliability of surface electromyography (sEMG) measurements after submersion (swimming) for 90 min. Isometric maximal voluntary contractions (MVC) on land and in water were collected from eight muscles on the right side of the body in 12 healthy participants (6 women and 6 men). Repeated measures analyses of variance (general linear model ANOVA) showed no significant differences in the peak amplitude MVC scores between land pre and post measurements for all muscles, p > .05. The mean of the Intraclass correlation coefficient (1, 1) for land pre and land post was .985 with (95% Cl = .978–.990), for land pre and water pre .976 (95% Cl = .964–.984) and for land pre and post, water pre and post .981 (95% Cl = .974–.987). Measuring sEMG on land before and after a prolonged submersion is highly reliable without additional waterproofing when using electrodes with 57 mm diameter.

• Olstad, Bjørn Harald; Zinner, Christoph; Cabri, Jan Maria Hendrick; Håkonsen, D. & Kjendlie, Per-Ludvik (2012). STRONG POSITIVE CORRELATIONS WERE FOUND BETWEEN MUSCLE ACTIVATION AND BREASTSTROKE SPEED MEASURED WITH 3D AUTOMATIC TRACKING. I Meeusen, R; Duchateau, J; Roelands, B; Klass, M; De Geus, B; Baudry, S & Tsolakidis, E (Red.), 17th annual Congress of the ECSS. BlosoVlaamseoverheid. ISSN 978-90902686-8-2. s. 463–463.
• Olstad, Bjørn Harald; Zinner, Christoph; Håkonsen, D.; Cabri, Jan Maria Hendrick & Kjendlie, Per-Ludvik (2012). 3D AUTOMATIC MOTION TRACKING IN WATER FOR MEASURING INTRA CYCLIC VELOCITY VARIATIONS IN BREASTSTROKE SWIMMING. I Meeusen, R; Duchateau, J; Roelands, B; Klass, M; De Geus, B; Baudry, S & Tsolakidis, E (Red.), 17th annual Congress of the ECSS. BlosoVlaamseoverheid. ISSN 978-90902686-8-2. s. 22–22.
• Olstad, Bjørn Harald; Cabri, Jan Maria Hendrick; Zinner, Christoph; Nunes, Neuza & Kjendlie, Per-Ludvik (2011). SEMG measurements on land and in water prior to and after 60-90 minutes of submersion (swimming) are highly reliable. Revista Portuguesa de Ciências do Desporto. ISSN 1645-0523. 11, s. 763–765. Vis sammendrag

  The purpose of this study was to investigate the reliability of surface electromyography (sEMG) measurements after being submerged (swimming) for 60-90 minutes. Isometric maximal voluntary contractions (MVC) on land and in water were collected of eight muscles in three males and three females (mean age 22.5±4.5 years). A paired samples t-test showed no significant differences in the mean MVC signal between pre and post test after prolonged water submersion (p<0.954 for average of the two highest MVC scores and p<0.946 for the highest MVC score pre and post submerging respectively). Intraclass Correlation (ICC)(1,1) were 0.977 and 0.972, the Chronbach’s alpha was 0.976 and 0.972. The mean coefficient of variation for all muscles was 11%. Testing sEMG in water exercises, before or after a prolonged submersion seems to be highly reliable.

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• Odberg, Ann-Helen; Tjellaug, Gisle Vedvik; Grydeland, May & Olstad, Bjørn Harald (2020). Opplæring og bading ute. 360 vandring.
• Olstad, Bjørn Harald (2018). Optical heart rate in swimming: a pilot study.
• Olstad, Bjørn Harald; Cabri, Jan Maria Hendrick & Kjendlie, Per-Ludvik (2018). Correspondence of muscular activation during maximal breaststroke swimming and self-selected drill exercises.
• Olstad, Bjørn Harald; Cabri, Jan Maria Hendrick & Kjendlie, Per-Ludvik (2017). A Common Drill Exercise In A World Champion Breaststroker - Does It Offer What It Promises? Medicine & Science in Sports & Exercise. ISSN 0195-9131. 49(5), s. 480–480.
• Olstad, Daniela Schäfer; Kjendlie, Per-Ludvik; Cabri, Jan Maria Hendrick & Olstad, Bjørn Harald (2017). Can Rate Of Perceived Exertion Be Used To Estimate Muscle Activation? Medicine & Science in Sports & Exercise. ISSN 0195-9131. 49(5), s. 1041–1041.
• Guignard, B; Olstad, Bjørn Harald; Escobar, David Simbaña; Lauer, Jessy; Kjendlie, Per-Ludvik & Rouard, A.H. (2015). Knee and ankle muscles coactivations in breaststroke swimming kick and recovery: Exploratory approach.
• Grydeland, May; Olstad, Bjørn Harald; Cabri, Jan Maria Hendrick & Kjendlie, Per-Ludvik (2015). Muscle activation and kinematic differences between female and male elite breaststroke swimmers.
• Olstad, Bjørn Harald; Grydeland, May; Vaz, Joao Rocha; Zinner, Christoph; Cabri, Jan Maria Hendrick & Kjendlie, Per-Ludvik (2015). Muscle Activation of World-Class Breaststroke Swimmers.
• Schäfer, Daniela; Olstad, Bjørn Harald & Wilhelm, Matthias (2015). Can Heart Rate Variability Segment Length During Orthostatic Test Be Reduced To 2 Min? Medicine & Science in Sports & Exercise. ISSN 0195-9131. 46(5), s. 38–38.
• Olstad, Bjørn Harald; Lauer, Jessy; Zinner, Christoph; Haakonsen, David; Cabri, Jan Maria Hendrick & Kjendlie, Per-Ludvik (2014). Muscle activation and kinematic differences between breaststroke swimming and technique/drill exercises: a case study of a world champion breaststroker.
• Kjendlie, Per-Ludvik; Pedersen, Tommy; Stallman, Robert K. & Olstad, Bjørn Harald (2014). The effects of unsteady water on choice of swimming stroke.
• Kjendlie, Per-Ludvik; Haakonsen, David & Olstad, Bjørn Harald (2014). Automatic 3D underwater motion capture is highly accurate.
• Olstad, Bjørn Harald & Ekeland, Halvor (2014). Differences in stroke length, frequency and velocity for the men's 100m long course freestyle for international and Norwegian finalists.
• Olstad, Bjørn Harald; Lauer, Jessy; Zinner, Christoph; Haakonsen, David; Cabri, Jan Maria Hendrick & Kjendlie, Per-Ludvik (2014). Muscle activation and kinematic differences between breaststroke swimming and technique/drill exercises: a case study of a world champion breaststroker. I Mason, Bruce (Red.), Proceedings of th XIIth International Symposium on Biomechanics and Medicine in Swimming. Australian Institute of Sport. ISSN 978-0-646-91868-6. s. 200–205.
• Olstad, Bjørn Harald; Zinner, Christoph; Haakonsen, David; Cabri, Jan Maria Hendrick & Kjendlie, Per-Ludvik (2014). A new approach for identifying phases of the breaststroke wave kick and calculation of feet slip using 3D automatic motion tracking. I Mason, Bruce (Red.), Proceedings of th XIIth International Symposium on Biomechanics and Medicine in Swimming. Australian Institute of Sport. ISSN 978-0-646-91868-6. s. 195–199.
• Olstad, Bjørn Harald; Zinner, Christoph; Haakonsen, David; Cabri, Jan Maria Hendrick & Kjendlie, Per-Ludvik (2014). A new approach for identifying phases of the breaststroke wave kick and calculation of feet slip using 3D automatic motion tracking.
• Guignard, B; Simbana, E.D.; Olstad, Bjørn Harald; Kjendlie, Per-Ludvik; Lauer, Jessy & Rouard, A.H. (2013). Ecological kinematics and electromyography approach of the lower limb in breaststroke.
• Kjendlie, Per-Ludvik & Olstad, Bjørn Harald (2012). Automatic 3D Motion Capture of Swimming: Marker Resistance. Medicine & Science in Sports & Exercise. ISSN 0195-9131. 44, s. 476–476.
• Olstad, Bjørn Harald; Cabri, Jan Maria Hendrick; Zinner, Christoph; Nunes, Neuza & Kjendlie, Per-Ludvik (2011). Mean and peak frequency in the SEMG Power-Spectrum is not different between land and water.
• Stallman, Robert Keig; Kjendlie, Per-Ludvik & Olstad, Bjørn Harald (2011). Bridging the gap - the transition between pool and open water : a pedagogical drowning prevention approach.
• Kjendlie, Per-Ludvik; Stallman, Robert Keig & Olstad, Bjørn Harald (2011). Water safety education is more than teaching swimming skills: comprehensive drowning prevention education.

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