The effect of inspiratory muscle fatigue on acid-base status and performance during race-paced middle-distance swimming

Effect of inspiratory muscle training on pulmonary function, respiratory muscle strength, aerobic performance, sports skills, and quality of life in wheelchair rugby athletes

INTRODUCTION

Inspiratory muscle training (IMT) has been used in sports to improve factors that can positively influence sports performance. However, the effects of IMT on athletes with disabilities are less well explored. This study aimed to investigate the effects of IMT on the pulmonary function, respiratory muscle strength, aerobic performance, sports skills, and quality of life (QoL) of wheelchair rugby (WCR) athletes.

METHODS

A pre-post-intervention case series study of IMT was carried out with six WCR athletes. Pulmonary function (spirometry), respiratory muscle strength (manovacuometry), aerobic (cardiopulmonary exercise test) and WCR skills (Beck Battery) performance and QoL (WHOQOL-DIS) were investigated. Participants were submitted to a six-week IMT with a linear load resistor involving 30 dynamic inspiratory maneuvers twice daily for five days/week.

RESULTS

Increases in maximum load (+14.6%; p = 0.03), maximum effort time (+19.4%; p = 0.03), absolute and percent of predicted maximal expiratory muscle pressure (both +13.2%; p = 0.04) and absolute and percent of predicted maximal inspiratory muscle pressure (both +28.6%; p = 0.04) were observed. No significant differences were observed for pulmonary function variables, WCR skills performance or QoL.

CONCLUSION

IMT seemed to be effective at improving the respiratory muscle strength and aerobic performance of WCR players but there was no impact on pulmonary function, sports skills or QoL.

Higher Blood Lactate with Prolongation of Underwater Section in Submaximal Front-Crawl Swimming

The underwater phase (UP) is highly important for overall swimming performance in most swimming events. However, the metabolic effects of the prolonged UP remain unclear. The purpose of this cross-sectional study was to compare the blood lactate response to submaximal front-crawl swimming with short and extended UP. Twelve (four females) junior competitive swimmers (aged 15.4 (1.4) years) undertook 200 m front-crawl swim trials in a 25 m pool at a pre-determined "anaerobic threshold" velocity on two occasions using short (<5 m) and extended (12.5 m) UP after each turn. Pacing and total time were ensured to be identical between the trials. Capillary blood lactate response was measured. Testing for 25 m swim time with <5 m and 12.5 m UP was conducted on a separate occasion. When athletes undertook and extended UP after each propulsion from the wall, their post-exercise blood lactate concentration reached 7.9 (2.1) mmol/L, more than two times higher than the response to trial with short UP (p < 0.001). All-out 25 m swimming with <5 m or 12.5 m UP disclosed no difference in locomotion velocity (p > 0.05). In conclusion, extending UP of submaximal front-crawl swimming close to maximally allowed during the races substantially increases blood lactate accumulation, i.e., increases the reliance on anaerobic metabolism. Therefore, extended UP is most likely counterproductive for the performance in long-distance swimming, at least for the athletes with a FINA score of <800. On the other hand, the extension of UP could be an effective strategy to train 'lactate tolerance', lactate shuttling, removal, and recycling.

Stability analysis and prediction of pacing in elite 1500 m freestyle male swimmers

This study aimed to analyse the stability of elite male long-distance swimmers (1500 m), and to identify the main predictors related to the pace. The performance of 16 elite male swimmers (22.59 ± 2.10 years-old) participating in the 1500 m event at the 2016 (London) and 2018 (Glasgow) LEN European Aquatic Championships were analysed. The lap performance, clean swim performance, turn performance, and a set of stroke mechanics variables were assessed. The lap performance presented a significant and moderate variation with all laps included (p < 0.001) and deleting the first and last lap (p = 0.002). Swimmers were significantly faster in the first half in comparison of the second. The total turn also presented a significant and moderate variation. The hierarchical linear modelling retained the time (estimate = 0.0019, p = 0.007), stroke frequency (estimate = -27.49, p < 0.001) and stroke length (estimate = -6.55, p < 0.001) as the main predictors of the clean swim performance. By contrast to the analysis based on the lap performance, clean swim performance presented a non-significant variation. Coaches should be aware that stroke length maintenance could negatively affect the clean swim performance, whereas a small increase of stroke frequency may present a meaningful enhancement of the total race time.

Inspiratory muscle fatigue at the swimming tumble turns: its occurrence and effects on kinematic parameters of the turns

Introduction: The present study had two objectives: 1) to investigate the effects of tumble turns on the development of inspiratory muscle fatigue (IMF) and compare this to whole swimming, and 2) to evaluate the effects of pre-induced IMF on the kinematic parameters of tumble turns. Fourteen young club-level swimmers (13 ± 2 years of ages) completed three swim trials. Methods: The first trial was used to determine the 400-m front crawl swim time at maximal effort (400FC). The other two trials consisted of a series of 15 tumble turns at the 400FC pace. In one of the turn-only trials, IMF was pre-induced (TURNS-IMF), whereas in the other turn-only trial it was not (TURNS-C). Results: Compared with baseline values, the values for maximal inspiratory mouth pressure (PImax) at the end of the swim were significantly lower at all trials. However, the magnitude of inspiratory muscle fatigue was less after TURNS-C (PImax decreased by 12%) than after 400FC (PImax decreased by 28%). The tumble turns were slower during 400FC than during TURNS-C and TURNS-IMF. In addition, compared to TURNS-C, turns in the TURNS-IMF were performed with higher rotation times and shorter apnea and swim-out times. Discussion: The results of the present study suggest that tumble turns put a strain on the inspiratory muscles and directly contribute to the IMF observed during 400FC swimming. Furthermore, pre-induced IMF resulted in significantly shorter apneas and slower rotations during tumble turns. IMF therefore has the potential to negatively affect overall swimming performance, and strategies should be sought to reduce its effects.

Analysis of pacing and kinematics in 3000 m freestyle in elite level swimmers

This study aimed to determine elite swimmers' pacing strategy in the 3000 m event and to analyse the associated performance variability and pacing factors. Forty-seven races were performed by 17 male and 13 female elite swimmers in a 25 m pool (20.7 ± 2.9 years; 807 ± 54 FINA points). Lap performance, clean swim velocity (CSV), water break time (WBT), water break distance (WBD), stroke rate (SR), stroke length (SL) and stroke index (SI) were analysed including and excluding the first (0-50 m) and last lap (2950-3000 m). The most common pacing strategy adopted was parabolic. Lap performance and CSV were faster in the first half of the race compared to the second half (p < 0.001). WBT, WBD, SL and SI were reduced (p < 0.05) in the second half compared to the first half of the 3000 m when including and excluding the first and last laps for both sexes. SR increased in the second half of the men's race when the first and last laps were excluded. All studied variables showed significant variation between the two halves of the 3000 m, the highest variation being obtained in WBT and WBD, suggesting that fatigue negatively affected swimming kinematics.

Change in short distance swimming performance following inspiratory muscle fatigue

BACKGROUND

Inspiratory muscle fatigue (IMF) may impair performance in a subsequent exercise. A few studies have reported that IMF decreased swimming performance in sub-maximal intensity or severe intensity domain. However, the impact of IMF on high-intensity short-duration swimming is not clear. The purpose of this study was to clarify the effect of pre-induced IMF on extreme intensity domain swimming.

METHODS

Seven male competitive swimmers swam two 100-m all-out front crawl swimming trials with and without pre-induced IMF. Maximal inspiratory and expiratory mouth pressure (PImax and PEmax, respectively) was used as indicators of inspiratory and expiratory muscle strength before and after swimming, and stroke parameters during swimming were measured. IMF was achieved by having the subjects breathe against an inspiratory pressure threshold load while generating 40% of their predetermined PImax for 10 min.

RESULTS

After the induction of IMF, swimming time (55.94 ± 1.15 s) was significantly slower compared with that in control swimming without IMF (54.09 ± 0.91 s) (p < 0.05). During swimming followed IMF, a significant decrease in stroke rate and a significant increase in stroke length were observed in the latter half of the 100-m swimming trial. In addition, the sense of dyspnea was significantly higher in swimming in the IMF condition than in control condition.

CONCLUSIONS

IMF prior to swimming negatively affects swimming performance in the extreme intensity domain. It is suggested that due to the dual use of respiration and generate propulsion in accessory respiratory muscles, IMF affected swimmers' ability to maintain swimming velocity.