Swimming Phase-Based Performance Evaluation Using a Single IMU in Main Swimming Techniques

Comprehensive monitoring of performance is essential for swimmers and swimming coaches to optimize the training. Regardless of the swimming technique, the swimmer passes various swimming phases from wall to wall, including a dive into the water or wall push-off, then glide and strokes preparation and finally, swimming up to the turn. The coach focuses on improving the performance of the swimmer in each of these phases. The purpose of this study was to assess the potential of using a sacrum-worn inertial measurement unit (IMU) for performance evaluation in each swimming phase (wall push-off, glide, stroke preparation and swimming) of elite swimmers in four main swimming techniques (i.e. front crawl, breaststroke, butterfly and backstroke). Nineteen swimmers were asked to wear a sacrum IMU and swim four one-way 25 m trials in each technique, attached to a tethered speedometer and filmed by cameras in the whole lap as reference systems. Based on the literature, several goal metrics were extracted from the instantaneous velocity (e.g. average velocity per stroke cycle) and displacement (e.g. time to reach 15 m from the wall) data from a tethered speedometer for the swimming phases, each one representing the goodness of swimmer’s performance. Following a novel approach, that starts from swimming bout detection and continues until detecting the swimming phases, the IMU kinematic variables in each swimming phase were extracted. The highly associated variables with the corresponding goal metrics were detected by LASSO (least absolute shrinkage and selection operator) variable selection and used for estimating the goal metrics with a linear regression model. The selected kinematic variables were relevant to the motion characteristics of each phase (e.g. selection of propulsion-related variables in wall push-off phase), providing more interpretability to the model. The estimation reached a determination coefficient (R2) value more than 0.75 and a relative RMSE less than 10% for most goal metrics in all swimming techniques. The results show that a single sacrum IMU can provide a wide range of performance-related swimming kinematic variables, useful for performance evaluation in four main swimming techniques.

Effect of long-haul transmeridian travel on recovery and performance in international level swimmers

This study holistically examined the effects of long-haul transmeridian travel (LHTT) on physiological, perceptual, sleep and performance markers in nine international level swimmers preparing for the 2019 FINA World Long Course Championships in Gwangju, South Korea. Baseline (BL) measurements were taken over two days during the week before a long-haul eastward flight across eight time-zones. Following the flight, measurements were taken over a six-day holding camp in Japan (C1-C6), and over four days at the competition venue in Gwangju before the Championships commenced (PR1-PR4). Salivary cortisol (sCort), immunoglobulin A (sIgA), alpha-amylase (sAA) concentrations and perceptual measures via the Liverpool John Moore's University Jetlag Questionnaire were assessed. Sleep was monitored using wrist activity monitors and self-report sleep diaries. Performance was assessed via squat jump (SJ), countermovement jump (CMJ) and a 4 × 100 m swim test. Participants perceived themselves to be significantly more fatigued and jet lagged than BL for five- and nine-days post-travel, respectively. Morning sCort decreased by 70% on C1 and remained significantly lower than BL until C6 ( p < 0.05). Sleep ratings improved significantly in comparison to BL from C5 onwards ( p < 0.05). Compared with BL, there was no significant change in swim performance or SJ height following travel; however, there was a 3.8 cm improvement ( p < 0.001) in CMJ height on C5. It took ten days for elite swimmers to perceive themselves recovered from jet lag following LHTT in an eastward direction across eight time-zones. LHTT did not negatively affect sleep or physical performance in the swimmers in comparison to BL.

The Impact of COVID-19 on the Preparation for the Tokyo Olympics: A Comprehensive Performance Assessment of Top Swimmers

Background: The Olympic preparation of athletes has been highly influenced by COVID and post-COVID syndrome. As the complex screening of athletes is essential for safe and successful sports, we aimed to repeat the 2019-year sports cardiology screening of the Olympic Swim Team before the Olympics and to compare the results of COVID and non-COVID athletes. Methods: Patient history, electrocardiogram, laboratory tests, body composition analysis, echocardiography, cardiopulmonary exercise test (CPET) were performed. We used time-ranking points to compare swimming performance. Results: From April 2019, we examined 46 elite swimmers (24 ± 4 years). Fourteen swimmers had COVID infection; all cases were mild. During CPET there was no difference in the performance of COVID (male: VO2 max 55 ± 4 vs. 56.5 ± 5 mL/kg/min, p = 0.53; female: VO2 max 54.6 ± 4 vs. 56 ± 5.5 mL/kg/min, p = 0.86) vs. non-COVID athletes (male VO2 max 56.7 ± 5 vs. 55.5 ± 4.5 mL/kg/min, p = 0.50; female 49.6 ± 3 vs. 50.7 ± 2.6 mL/kg/min, p = 0.47) between 2019 and 2021. When comparing the time results of the National Championships, 54.8% of the athletes showed an improvement (p = 0.75). Conclusion: COVID infection with short-term detraining did not affect the performance of well-trained swimmers. According to our results, the COVID pandemic did not impair the effectiveness of the preparation for the Tokyo Olympics.

Metabolic Power, Active Drag, Mechanical and Propelling Efficiency of Elite Swimmers at 100 Meter Events in Different Competitive Swimming Techniques

Eight elite swimmers—four females and four males—were studied, each of whom specialized in different swimming techniques and ranked among the top 10 in the world in the 100 m event in their swimming specialty. Methods included a complex of physiological, biomechanical and hydrodynamic procedures, as well as mathematical modeling. During the special preparation period for the 2017 Swimming World Championship, all subjects performed an 8 × 100 m swimming step-test using their main swimming technique. The relationships between velocity, mechanical and metabolic power were obtained and analyzed for each swimming technique. It was found that, at the last stage of the test, in all swimming techniques, men demonstrated higher values of metabolic power (Pai = 3346–3560 W) and higher mechanical efficiency (eg = 0.062–0.068) than women (Pai = 2248–2575 W; eg = 0.049–0.052). As for propelling efficiency, women (ep = 0.67–0.71) and men (ep = 0.65–0.71) did not differ from each other. Results showed that the frontal component of active drag force is the main reason for the existing differences in maximal swimming velocity between different techniques, since no relevant differences were observed for mechanical and propelling efficiencies among swimming techniques.

Underwater and Surface Swimming Parameters Reflect Performance Level in Elite Swimmers

Although the role of underwater phases is well-known, no study has taken an interest in describing and quantifying the distance and time spent in apnea as a condition for optimal performance. This study aimed to investigate the impact of time and distance spent underwater and surface parameters on the swimming performance of elite swimmers. The performances of 79 swimmers in 100-m freestyle were analyzed (short-course). The underwater and spatiotemporal parameters of three groups have been recorded: finalists of the 2018 World Swimming Championships (WORLD), French swimmers who reached a 100 m performance time under 50 s at the 2018 French National Championships (UND50), and those who reached a 100 m performance time above 50 s (UP50). The WORLD group spent more distance underwater (37.50 ± 4.92 m) in comparison with UND50 (31.90 ± 4.88 m, p &lt; 0.05) and UP50 (31.94 ± 4.93 m, p &lt; 0.01) groups. The total percentage of non-swimming time was higher for WORLD (39.11 ± 4.73%) vs. UND50 (34.21 ± 4.55%, p &lt; 0.05) and UP50 (33.94 ± 5.00%, p &lt; 0.01). In addition, underwater speed was higher for WORLD (2.54 ± 0.05 m/s) compared with UND50 (2.46 ± 0.09 m/s, p &lt; 0.05) and UP50 (2.38 ± 0.11 m/s, p &lt; 0.01). Three parameters among the underwater phases (i.e. distance underwater, speed underwater, and total percentage of non-swimming time) determine the 100-m freestyle short course performance. These data suggest an appropriate focus on specific apnea training to improve underwater skills during short-course swimming performances.

Heart Rate Variability in Elite Swimmers before, during and after COVID-19 Lockdown: A Brief Report on Time Domain Analysis

Background: Many athletes worldwide have endured home confinement during the COVID-19 pandemic, and their opportunities to train were strongly limited. This study describes the impact of lockdown on training volume and heart rate variability (HRV) in elite swimmers. Methods: HRV data of seven elite males were collected each Monday morning over 20 weeks, including 8 weeks of lockdown. The training volume was quantified retrospectively. Results: During the lockdown period (weeks 4–11) swimming was not allowed, and the total training volume was reduced by 55.2 ± 7.5% compared to the baseline volume (from 27.2 to 12.2 training hours). This drop was associated with a decrease in vagal activity (a 9.2 ± 5.4% increase in resting HR and a 6.5 ± 3.4% decrease in the natural logarithm of rMSSD from baseline values). After the lockdown (weeks 12–20), the training volume was gradually increased before attaining 68.8% and 88.2% of the baseline training volume at weeks 15 and 17, respectively. Resting HR and Ln rMSSD returned to baseline values four weeks after the lockdown. Conclusions: The lockdown period induced a decreased training volume which was associated with a decrease in vagal activity. However, HRV values returned to the baseline 4 weeks after the resumption of swimming training.

Effect of glutathione supplementation on swimmers’ performance

Background and Study Aim. Continuously increasing the volume and intensity of the training sessions often leads to overtraining. It has been demonstrated that glutathione supplementation might improve the aerobic metabolism in skeletal muscle and reduce exercise-induced muscle fatigue. The aim of the study was to assess the effect of glutathione supplementation on fatigue, recovery processes, and competitive results of elite swimmers during a six-week training period. Material and Methods. Twenty-four elite swimmers (10 women and 14 men) from the Bulgarian national swimming team, with a mean age of 18.7±3.78 years, took part in this double-blind placebo control study. The swimmers from the experimental group were supplemented once a day with a capsule of 250mg glutathione, whilst the swimmers from the control group took a placebo once a day. The urine concentration levels of cortisol and cortisone, as well as the degree of overtraining, were evaluated on the 1st(T1), 14th(T2), 28th(T3), and 42nd(T4) days. Anthropometric measurements and a nutritional assessment were performed at T1 and T4. Results. The swimmers showed a gradual decrease of cortisol and cortisone during the study, with significantly lower concentrations in the experimental vs the control group at T4 (19.4 vs 42.5 ng/mL, p < 0.05). At the end of the study, the swimmers from the experimental group showed improvements in their time in 41 out of the 43 swimming events, whilst those from the control group had significantly smaller improvements (-1.66 vs -0.97%, p < 0.05). Conclusions. In conclusion, glutathione supplementation at a dose of 250mg/day for six weeks improves the adaptation of elite swimmers towards training schedules, which is likely to lead to better sports results.