Repeated-sprint training in hypoxia induced by voluntary hypoventilation improves running repeated-sprint ability in rugby players

Additional Benefits of Repeated-Sprint Training With Prolonged End-Expiratory Breath Holding for Improving Repeated-Sprint Ability in Semiprofessional Soccer Players

PURPOSE

To investigate the effects of running repeated-sprint training with voluntary hypoventilation at low lung volume (RSH-VHL) including prolonged end-expiratory breath holding (EEBH) on running repeated-sprint ability (RSA).

METHODS

Twenty semiprofessional male soccer players completed 12 sessions of repeated 50-m running sprints over a 6-week period either with EEBH (RSH-VHL, n = 10) or with normal breathing (RSN, n = 10). Before (Pre) and after (Post) training, a running RSA test consisting of performing maximum 30-m "all-out" sprints until task failure, with a minimum of 10 sprints, was implemented.

RESULTS

The maximum number of sprints was increased at Post compared to Pre in RSH-VHL only (13.5 [4.4] vs 7.7 [2.3], P < .01) and was greater in RSH-VHL than in RSN at Post (P < .01). The mean velocity for sprints 1 to 10 and sprints 6 to 10 was increased in both groups at Post (P < .01) but was greater in RSH-VHL than in RSN after the training period (P < .01). There was no change in the reference velocity (P = .80) or in the maximal velocity reached during the RSA test (P = .52) in either group. The mean minimal arterial oxygen saturation recorded during training at the end of the sprints was lower in RSH-VHL (78.5% [1.4%]) than in RSN (97.3% [0.1%]).

CONCLUSIONS

This study shows that an RSH-VHL intervention including prolonged EEBH can provide an additional benefit for improving RSA in male semiprofessional soccer players. This result may be due in large part to the strong hypoxic effect induced by the prolonged EEBH.

The Effects of a Short-Term Supplemental Breathwork Protocol on the Aerobic Performance of Recreational Runners

We investigated the effects of a functional breathing program on the aerobic performance of recreational runners. Runners participated in an aerobic endurance training program with functional breathing (FBP; n = 8, 34.8 ± 5.1 yrs, 25.3 ± 2.5 kg·m2) or without functional breathing (CON; n = 8, 29 ± 5 yrs, 23 ± 2 kg·m2). The treatment group underwent daily breathing exercises, and nasal-only breathing during low-intensity sessions of the training program. The primary outcome variables measured before and after the program included the following: the breath-hold time at rest, the duration and VO2max with nasal-only breathing, and the VO2max with normal breathing during a graded running test. The data were analyzed using two-way ANOVA (p < 0.05). We found a significant group x time interaction for breath-hold time (∆ from PRE: +1.9 s [CON], +11.7 s [FBP]; p = 0.04; d = 1.13). However, the changes in the time and VO2max with nasal-only breathing, and in the VO2max with normal breathing, did not differ between the FBP and CON groups. A small but significant time (main) effect for the increase in VO2max (~3.0%, p < 0.05) suggested that both groups had adequate stimuli for physiological adaptations. The four-week supplementary functional breathing protocol increased the breath-hold time, but not the maximum nasal-only breathing time, nasal-only breathing VO2max, or VO2max, in recreational runners.

Cardiorespiratory and muscle oxygenation responses to voluntary hypoventilation at low lung volume in upper body repeated sprints

PURPOSE

To investigate the impact of voluntary hypoventilation at low lung volumes (VHL) during upper body repeated sprints (RS) on performance, metabolic markers and muscle oxygenation in Brazilian Jiu-Jitsu (BJJ) athletes.

METHODS

Eighteen male well-trained athletes performed two randomized RS sessions, one with normal breathing (RSN) and another with VHL (RS-VHL), on an arm cycle ergometer, consisting of two sets of eight all-out 6-s sprints performed every 30 s. Peak (PPO), mean power output (MPO), and RS percentage decrement score were calculated. Arterial oxygen saturation (SpO2), heart rate (HR), gas exchange, and muscle oxygenation of the long head of the triceps brachii were continuously recorded. Blood lactate concentration ([La]) was measured at the end of each set. Bench press throw peak power (BPPP) was recorded before and after the RS protocol.

RESULTS

Although SpO2 was not different between conditions, PPO and MPO were significantly lower in RS-VHL. V ˙ E, HR, [La], and RER were lower in RS-VHL, and VO2 was higher in RS-VLH than in RSN. Muscle oxygenation was not different between conditions nor was its pattern of change across the RS protocol influenced by condition. [La] was lower in RS-VHL than in RSN after both sets.

CONCLUSION

Performance was significantly lower in RS-VHL, even though SPO2 was not consistent with hypoxemia. However, the fatigue index was not significantly affected by VHL, nor was the neuromuscular upper body power after the RS-VHL protocol. Additionally, [La] was lower, and oxygen consumption was higher in RS-VHL, suggesting a higher aerobic contribution in this condition.

Effects of Apnea-Induced Hypoxia on Hypoalgesia in Healthy Subjects

INTRODUCTION

Exercise-induced hypoalgesia is a phenomenon in which exercise bouts induce a reduction in pain sensitivity. Apnea training involves similar characteristics that could potentially induce hypoalgesia.

OBJECTIVES

The objectives of this study are to explore the effect of apnea training on hypoalgesia; assess the correlation between conditioned pain modulation (CPM) response and apnea-induced hypoalgesia; and examine the association between hypoalgesia with hypoxemia, and heart rate (HR) during apnea.

METHODS

A randomized controlled trial was conducted comparing a walking protocol employing intermittent apnea compared with normal breathing in healthy volunteers. Hypoalgesia was tested with pressure pain thresholds (PPTs) and CPM. Oxygen saturation (SpO2) and HR were also tested.

RESULTS

Relevant but not significant changes were detected in the thumb (MD = 0.678 kg/cm2), and tibialis (MD = 0.718 kg/cm2) in favor of the apnea group. No significant differences were detected in CPM. The apnea group presented lower SpO2, but HR values similar to those of the control group during the intervention. Basal CPM and intrasession hypoxemia significantly correlated with the PPT response. However, HR did not correlate with the PPT response.

CONCLUSIONS

The current results suggest a trend, though not statistically significant, toward an improvement in the PPT in favor of apnea training compared to normal breathing. Nevertheless, subjects who presented greater basal CPM and lower oxygen saturation during the session presented a greater PPT response, suggesting the possibility of mediators of response. Future investigations should clarify this phenomenon.

Repeated Sprint Training in Hypoxia Improves Repeated Sprint Ability to Exhaustion Similarly in Active Males and Females

PURPOSE

The aim of this study was to compare the physiological adaptations of males and females to repeated sprint training in hypoxia (RSH).

METHODS

Active males and females completed 7 wk of repeated sprint training in normoxia (RSN; F i O 2 = 0.209, males: n = 11, females: n = 8) or RSH (F i O 2 = 0.146, males: n = 12, females: n = 10). Before (Pre-) and after (Post-) training, a repeated sprint ability (RSA) test was performed (10-s cycle sprints with 20-s recovery between sprints, until exhaustion), and aerobic and anaerobic qualities were evaluated in normoxia.

RESULTS

The number of sprints during RSA increased after training in HYP from 11 to 21 in males and from 8 to 14 in females ( P < 0.001, 95% confidence interval = 5-11), without significant changes after RSN (10 vs 14 and 8 vs 10 in males and females, respectively). No improvements in mean or peak power output were found in either group. Total work during RSA improved after training in all groups (+9 ± 2 kJ, P < 0.001). Tissue saturation index during the repeated sprints was higher in females than males (+10% ± 2%, P < 0.001). The difference in tissue saturation index between the recovery and sprint phases remained unchanged after training. O 2 peak during an incremental exercise test increased in all groups (+3 ± 1 mL·kg -1 ·min -1 , P = 0.039). Mean power output during a Wingate test also increased in both males and females in RSN and RSH (+0.38 ± 0.18 W·kg -1 , P = 0.036). No changes were observed in hematological parameters after training.

CONCLUSIONS

Seven weeks of RSH further increased the number of repeated sprints performed to exhaustion compared with RSN in females, in the same order of magnitude as in males.

Hypoventilation training including maximal end-expiratory breath holding improves the ability to repeat high-intensity efforts in elite judo athletes

Purpose

To investigate the effects of a repeated-sprint training in hypoxia induced by voluntary hypoventilation at low lung volume (RSH-VHL) including end-expiratory breath holding (EEBH) of maximal duration.

Methods

Over a 4-week period, twenty elite judo athletes (10 women and 10 men) were randomly split into two groups to perform 8 sessions of rowing repeated-sprint exercise either with RSH-VHL (each sprint with maximal EEBH) or with unrestricted breathing (RSN, 10-s sprints). Before (Pre-), 5 days after (Post-1) and 12 days after (Post-2) the last training session, participants completed a repeated-sprint ability (RSA) test on a rowing ergometer (8 × 25-s "all-out" repetitions interspersed with 25 s of passive recovery). Power output (PO), oxygen uptake, perceptual-motor capacity (turning off a traffic light with a predetermined code), cerebral (Δ[Hbdiff]) and muscle (Δ[Hb/Mb]diff) oxygenation, cerebral total haemoglobin concentration (Δ[THb]) and muscle total haemoglobin/myoglobin concentration (Δ[THb/Mb]) were measured during each RSA repetition and/or recovery period.

Results

From Pre-to Post-1 and Post-2, maximal PO, mean PO (MPO) of the first half of the test (repetitions 1-4), oxygen uptake, end-repetition cerebral Δ[Hbdiff] and Δ[THb], end-repetition muscle Δ[Hb/Mb]diff and Δ[THb/Mb] and perceptual-motor capacity remained unchanged in both groups. Conversely, MPO of the second half of the test (repetitions 5-8) was higher at Post-1 than at Pre-in RSH-VHL only (p < 0.01), resulting in a lower percentage decrement score over the entire RSA test (20.4% ± 6.5% vs. 23.9% ± 7.0%, p = 0.01). Furthermore, MPO (5-8) was greater in RSH-VHL than in RSN at Post-1 (p = 0.04). These performance results were accompanied by an increase in muscle Δ[THb/Mb] (p < 0.01) and a concomitant decrease in cerebral Δ[THb] (p < 0.01) during the recovery periods of the RSA test at Post-1 in RSH-VHL.

Conclusion

Four weeks of RSH-VHL including maximal EEBH improved the ability of elite judo athletes to repeat high-intensity efforts. The performance improvement, observed 5 days but not 12 days after training, may be due to enhanced muscle perfusion. The unchanged oxygen uptake and the decrease in cerebral regional blood volume observed at the same time suggest that a blood volume redistribution occurred after the RSH-VHL intervention to meet the increase in muscle perfusion.

Apnoea as a novel method to improve exercise performance: A current state of the literature

Acute breath-holding (apnoea) induces a spleen contraction leading to a transient increase in haemoglobin concentration. Additionally, the apnoea-induced hypoxia has been shown to lead to an increase in erythropoietin concentration up to 5 h after acute breath-holding, suggesting long-term haemoglobin enhancement. Given its potential to improve haemoglobin content, an important determinant for oxygen transport, apnoea has been suggested as a novel training method to improve aerobic performance. This review aims to provide an update on the current state of the literature on this topic. Although the apnoea-induced spleen contraction appears to be effective in improving oxygen uptake kinetics, this does not seem to transfer into immediately improved aerobic performance when apnoea is integrated into a warm-up. Furthermore, only long and intense apnoea protocols in individuals who are experienced in breath-holding show increased erythropoietin and reticulocytes. So far, studies on inexperienced individuals have failed to induce acute changes in erythropoietin concentration following apnoea. As such, apnoea training protocols fail to demonstrate longitudinal changes in haemoglobin mass and aerobic performance. The low hypoxic dose, as evidenced by minor oxygen desaturation, is likely insufficient to elicit a strong erythropoietic response. Apnoea therefore does not seem to be useful for improving aerobic performance. However, variations in apnoea, such as hypoventilation training at low lung volume and repeated-sprint training in hypoxia through short end-expiratory breath-holds, have been shown to induce metabolic adaptations and improve several physical qualities. This shows promise for application of dynamic apnoea in order to improve exercise performance. HIGHLIGHTS: What is the topic of this review? Apnoea is considered as an innovative method to improve performance. This review discusses the effectiveness of apnoea (training) on performance. What advances does it highlight? Although the apnoea-induced spleen contraction and the increase in EPO observed in freedivers seem promising to improve haematological variables both acutely and on the long term, they do not improve exercise performance in an athletic population. However, performing repeated sprints on end-expiratory breath-holds seems promising to improve repeated-sprint capacity.

Effects of Repeated High-Intensity Effort Training or Repeated Sprint Training on Repeated High-Intensity Effort Ability and In-Game Performance in Professional Rugby Union Players

ABSTRACT

Glaise, P, Rogowski, I, and Martin, C. Effects of repeated high-intensity effort training or repeated sprint training on repeated high-intensity effort ability and in-game performance in professional rugby union players. J Strength Cond Res 38(5): 932-940, 2024-This study investigated the effects of repeated high-intensity efforts (RHIE) training compared with repeated sprint exercise (RSE) training on RHIE ability (RHIEa) and in-game performance in professional rugby union players. Thirty-nine, male, professional, rugby union players were randomly assigned to 3 training groups (RHIE training, RSE training, and control). Repeated high-intensity effort ability and high-intensity effort characteristics (including sprints, acceleration, and contact efforts) during official games were measured before and after a 10-week specific (RHIE, RSE, or control) training period. The results of this study showed that concerning RHIEa, both the RHIE and RSE training significantly increased the players' average sprint velocity ( p < 0.001, d = -0.39 and p < 0.001, d = -0.53 respectively), average sled push velocity (ASPV; p < 0.001, d = -0.81 and p = 0.017, d = -0.48 respectively), and RHIE score ( p < 0.001, d = -0.72 and p < 0.001, d = -0.60 respectively). Repeated high-intensity effort training trended in a smaller increase in average sprint velocity than RSE training, a larger increase in ASPV, and a similar increase in RHIE score. Concerning in-game high-intensity efforts, both the RHIE and RSE training produced significant improvements in the number of sprints ( p = 0.047, d = -0.28 and p < 0.001, d = -0.47 respectively), total distance ( p < 0.001, d = -0.50 and p = 0.002, d = -0.38 respectively), the number of accelerations ( p < 0.001, d = -0.37 and p = 0.003, d = -0.32 respectively), and contact rate ( p < 0.001, d = -0.97 and p = 0.020, d = -0.28 respectively). Conversely, the magnitude of the increase in contact rate was almost twice as high in RHIE compared with RSE training. To conclude, the findings of this study were that both RSE and RHIE training are effective methods for developing RHIEa and in-game high-intensity efforts in professional rugby union. In practical applications, as the gains in certain abilities and game performance data differed depending on the training method chosen, we suggest that coaches choose the most appropriate method according to the profile of the players, their position, and the style of play they want to develop.

Effects of a 6-Week Repeated-Sprint Training With Voluntary Hypoventilation at Low and High Lung Volume on Repeated-Sprint Ability in Female Soccer Players

PURPOSE

To investigate the effects of repeated-sprint training with voluntary hypoventilation at low (RSH-VHL) and high (RS-VHH) lung volume on repeated-sprint ability (RSA) in female athletes.

METHODS

Over a 6-week period, 24 female soccer players completed 12 sessions of repeated 30-m running sprints with end-expiratory breath holding (RSH-VHL, n = 8), end-inspiratory breath holding (RS-VHH, n = 8), or unrestricted breathing (RS-URB, n = 8). Before and after training, a running RSA test consisting of performing 30-m all-out sprints until exhaustion was implemented.

RESULTS

From before to after training, the number of sprints completed during the RSA test was increased in both RSH-VHL (19.3 [0.9] vs 22.6 [0.9]; P < .01) and RS-VHH (19.3 [1.5] vs 20.5 [1.7]; P < .01) but not in RS-URB (19.4 [1.3] vs 19.5 [1.7]; P = .67). The mean velocity and the percentage decrement score calculated over sprints 1 to 17 were, respectively, higher (82.2% [1.8%] vs 84.6% [2.1%] of maximal velocity) and lower (23.7% [3.1%] vs 19.4% [3.2%]) in RSH-VHL (P < .01), whereas they remained unchanged in RS-VHH and RS-URB. The mean arterial oxygen saturation recorded during training at the end of the sprints was lower in RSH-VHL (92.1% [0.4%]) than in RS-VHH (97.3% [0.1%]) and RS-URB (97.8% [0.1%]).

CONCLUSIONS

This study shows that female athletes can benefit from the RSH-VHL intervention to improve RSA. The performance gains may have been limited by the short sprinting distance with end-expiratory breath holding, which provoked only moderate hypoxemia. The increase in the number of sprints in RS-VHH seems to show that factors other than hypoxia may have played a role in RSA improvement.

Effect of dry dynamic apnea on aerobic power in elite rugby athletes: a warm-up method

Objective: While long-term dynamic breath-holding training has been extensively studied to enhance cardiopulmonary function in athletes, limited research has explored the impact of a single breath-holding session on subsequent athletic capacity. In addition, Dry Dynamic Apnea (DA) has a more immediate physiological response than wet and static breath-holding. This study aims to assess the immediate effects of a single session of DA on the aerobic power and hematological parameters of elite athletes. Methods: Seventeen elite male rugby athletes (average age 23.5 ± 1.8) participated in this study. Two warm-up protocols were employed prior to incremental exercise: a standard warm-up (10 min of no-load pedaling) and a DA warm-up (10 min of no-load pedaling accompanied by six maximum capacity breath holds, with 30 s between each breath hold). Fingertip blood indicators were measured before and after warm-up. The incremental exercise test assessed aerobic parameters with self-regulation applied throughout the study. Results: Compared to the baseline warm-up, the DA warm-up resulted in a significant increase in VO2peak from 3.14 to 3.38 L/min (7.64% change, p < 0.05). HRmax increased from 170 to 183 bpm (7.34% change, p < 0.05), and HRpeak increased from 169 to 182 bpm (7.52% change, p < 0.05). Hematocrit and hemoglobin showed differential changes between the two warm-up methods (PHematocrit = 0.674; Phemoglobin = 0.707). Conclusion: This study investigates how DA influences physiological factors such as spleen contraction, oxygen uptake, and sympathetic nerve activation compared to traditional warm-up methods. Immediate improvements in aerobic power suggest reduced vagus nerve stimulation, heightened sympathetic activity, and alterations in respiratory metabolism induced by the voluntarily hypoxia-triggered warm-up. Further research is warranted to comprehensively understand these physiological responses and optimize warm-up strategies for elite athletic performance.

Different categories of VO2 kinetics in the 'extreme' exercise intensity domain

The aim of this study was to classify potential sub-zones within the extreme exercise domain. Eight well-trained male cyclists participated in this study. The upper boundary of the severe exercise domain (Pupper-bound) was estimated by constant-work-rate tests. Then three further extreme-work-rate tests were performed in discrete regions within the extreme domain: extreme-1) at a work-rate greater than the Pupper-bound providing an 80-110-s time to task failure; extreme-2) a 30-s maximal sprint; and extreme-3) a 4-s maximal sprint. Different functions were used to describe the behaviour of the V ˙ O 2 kinetics over time. V ˙ O 2 on-kinetics during extreme-1 exercise was best described by a single-exponential model (R2 ≥ 0.97; SEE ≤ 0.10; p < 0.001), and recovery V ˙ O 2 decreased immediately after the termination of exercise. In contrast, V ˙ O 2 on-kinetics during extreme-2 exercise was best fitted by a linear function (R2 ≥ 0.96; SEE ≤ 0.16; p < 0.001), and V ˙ O 2 responses continued to increase during the first 10-20 s of recovery. During the extreme-3 exercise, V ˙ O 2 could not be modelled due to inadequate data, and there was an M-shape recovery V ˙ O 2 response with an exponential decay at the end. The V ˙ O 2 response to exercise across the extreme exercise domain has distinct features and must therefore be characterised with different fitting strategies in order to describe the responses accurately.

The Acute Demands of Repeated-Sprint Training on Physiological, Neuromuscular, Perceptual and Performance Outcomes in Team Sport Athletes: A Systematic Review and Meta-analysis

BACKGROUND

Repeated-sprint training (RST) involves maximal-effort, short-duration sprints (≤ 10 s) interspersed with brief recovery periods (≤ 60 s). Knowledge about the acute demands of RST and the influence of programming variables has implications for training prescription.

OBJECTIVES

To investigate the physiological, neuromuscular, perceptual and performance demands of RST, while also examining the moderating effects of programming variables (sprint modality, number of repetitions per set, sprint repetition distance, inter-repetition rest modality and inter-repetition rest duration) on these outcomes.

METHODS

The databases Pubmed, SPORTDiscus, MEDLINE and Scopus were searched for original research articles investigating overground running RST in team sport athletes ≥ 16 years. Eligible data were analysed using multi-level mixed effects meta-analysis, with meta-regression performed on outcomes with ~ 50 samples (10 per moderator) to examine the influence of programming factors. Effects were evaluated based on coverage of their confidence (compatibility) limits (CL) against elected thresholds of practical importance.

RESULTS

From 908 data samples nested within 176 studies eligible for meta-analysis, the pooled effects (± 90% CL) of RST were as follows: average heart rate (HRavg) of 163 ± 9 bpm, peak heart rate (HRpeak) of 182 ± 3 bpm, average oxygen consumption of 42.4 ± 10.1 mL·kg-1·min-1, end-set blood lactate concentration (B[La]) of 10.7 ± 0.6 mmol·L-1, deciMax session ratings of perceived exertion (sRPE) of 6.5 ± 0.5 au, average sprint time (Savg) of 5.57 ± 0.26 s, best sprint time (Sbest) of 5.52 ± 0.27 s and percentage sprint decrement (Sdec) of 5.0 ± 0.3%. When compared with a reference protocol of 6 × 30 m straight-line sprints with 20 s passive inter-repetition rest, shuttle-based sprints were associated with a substantial increase in repetition time (Savg: 1.42 ± 0.11 s, Sbest: 1.55 ± 0.13 s), whereas the effect on sRPE was trivial (0.6 ± 0.9 au). Performing two more repetitions per set had a trivial effect on HRpeak (0.8 ± 1.0 bpm), B[La] (0.3 ± 0.2 mmol·L-1), sRPE (0.2 ± 0.2 au), Savg (0.01 ± 0.03) and Sdec (0.4; ± 0.2%). Sprinting 10 m further per repetition was associated with a substantial increase in B[La] (2.7; ± 0.7 mmol·L-1) and Sdec (1.7 ± 0.4%), whereas the effect on sRPE was trivial (0.7 ± 0.6). Resting for 10 s longer between repetitions was associated with a substantial reduction in B[La] (-1.1 ± 0.5 mmol·L-1), Savg (-0.09 ± 0.06 s) and Sdec (-1.4 ± 0.4%), while the effects on HRpeak (-0.7 ± 1.8 bpm) and sRPE (-0.5 ± 0.5 au) were trivial. All other moderating effects were compatible with both trivial and substantial effects [i.e. equal coverage of the confidence interval (CI) across a trivial and a substantial region in only one direction], or inconclusive (i.e. the CI spanned across substantial and trivial regions in both positive and negative directions).

CONCLUSIONS

The physiological, neuromuscular, perceptual and performance demands of RST are substantial, with some of these outcomes moderated by the manipulation of programming variables. To amplify physiological demands and performance decrement, longer sprint distances (> 30 m) and shorter, inter-repetition rest (≤ 20 s) are recommended. Alternatively, to mitigate fatigue and enhance acute sprint performance, shorter sprint distances (e.g. 15-25 m) with longer, passive inter-repetition rest (≥ 30 s) are recommended.

Effects of apnoea training on aerobic and anaerobic performance: A systematic review and meta-analysis

Background Trained breath-hold divers have shown physiological adaptations that might improve athletes’ aerobic and anaerobic performance.

Objective This study aimed to systematically review the scientific literature and perform a meta-analysis to assess the effects of voluntary apnoea training on markers of anaerobic and aerobic performance, such as blood lactate and VO2max.

Methods A literature search on three databases (Web of Science, PubMed and SCOPUS) was conducted in March 2022. The inclusion criteria were 1) peer-reviewed journal publication; 2) clinical trials; 3) healthy humans; 4) effects of apnoea training; 5) variables included markers of aerobic or anaerobic performance, such as lactate and VO2max.

Results 545 manuscripts were identified following database examination. Only seven studies met the inclusion criteria and were, therefore, included in the meta-analysis. 126 participants were allocated to either voluntary apnoea training (ApT; n = 64) or normal breathing (NB; n = 63). Meta-analysis on the included studies demonstrated that ApT increased the peak blood lactate concentration more than NB (MD = 1.89 mmol*L−1 [95% CI 1.05, 2.73], z = 4.40, p &lt; 0.0001). In contrast, there were no statistically significant effects of ApT on VO2max (MD = 0.89 ml*kg−1*min−1 [95% CI −1.23, 3.01], z = 0.82, p = 0.41).

Conclusion ApT might be an alternative strategy to enhace anaerobic performance associated with increased maximum blood lactate; however, we did not find evidence of ApT effects on physiological aerobic markers, such as VO2max.

Systematic Review Registration: [PRISMA], identifier [registration number].

Comparison of systemic and peripheral responses during high-intensity interval exercise under voluntary hypoventilation vs. hypoxic conditions

[Purpose]

This study aimed to determine the systemic and peripheral responses to high-intensity interval exercise (HIIE) with voluntary hypoventilation at low lung volume (VHL) or HIIE under hypoxic conditions.

[Methods]

Ten male participants completed a single session of HIIE (three sets of 6 × 8-s high-intensity pedaling at 170% of maximal oxygen uptake [VO_2max]) under three different conditions: normoxia with normal breathing (NOR: 23 °C, 20.9% of fraction of inspired oxygen [FiO₂]), hypoxia with normal breathing (HYP: 23 °C, 14.5% FiO₂), and normoxia with VHL (VHL: 23 °C, 20.9% FiO₂). A randomized crossover design was used. Power output, arterial oxygen saturation (SpO₂), heart rate, and muscle oxygenation were monitored during the exercise and the 16-s recovery. Muscle blood flow (mBF) of the vastus lateralis was also evaluated.

[Results]

SpO₂ during the exercise and the 16-s recovery in the VHL group was significantly lower than in that of the NOR group. However, this parameter in the VHL group was significantly higher than that of the HYP group (NOR: 94.9 ± 0.4%, HYP: 82.8 ± 1.2%, VHL: 90.4 ± 0.5%; p < 0.001). Muscle oxygen saturation was significantly lower in the HYP group than those in the VHL and NOR groups (NOR: 79.6 ± 17.4%, HYP: 65.5 ± 7.7%, VHL: 74.4 ± 7.8%; p = 0.024). No significant difference in this parameter was observed between the VHL and NOR groups (p > 0.05). Additionally, the exercise-induced increase in mBF did not differ significantly among three groups (p > 0.05).

[Conclusion]

HIIE-induced SpO₂ decrease was smaller under hypoxic conditions than during VHL. Moreover, mBF was not enhanced by the addition of VHL during HIIE.

Ketone Bodies Impact on Hypoxic CO2 Retention Protocol During Exercise

Exogenous ketone esters have demonstrated the capacity to increase oxygen availability during acute hypoxic exposure leading to the potential application of their use to mitigate performance declines at high altitudes. Voluntary hypoventilation (VH) with exercise reliably reduces oxygen availability and increases carbon dioxide retention without alterations to ambient pressure or gas content. Utilizing a double-blind randomized crossover design, fifteen recreational male distance runners performed submaximal exercise (4 × 5 min; 70% VO₂ Max) with VH. An exogenous ketone ester (KME; 573 mg⋅kg^–1) or iso-caloric flavor matched placebo (PLA) was consumed prior to exercise. Metabolites, blood gases, expired air, heart rate, oxygen saturation, cognition, and perception metrics were collected throughout. KME rapidly elevated R-β-hydroxybutyrate and reduced blood glucose without altering lactate production. KME lowered pH, bicarbonate, and total carbon dioxide. VH with exercise significantly reduced blood (SpO₂) and muscle (SmO₂) oxygenation and increased cognitive mean reaction time and respiratory rate regardless of condition. KME administration significantly elevated respiratory exchange ratio (RER) at rest and throughout recovery from VH, compared to PLA. Blood carbon dioxide (PCO₂) retention increased in the PLA condition while decreasing in the KME condition, leading to a significantly lower PCO₂ value immediately post VH exercise (IPE; p = 0.031) and at recovery (p = 0.001), independent of respiratory rate. The KME’s ability to rapidly alter metabolism, acid/base balance, CO₂ retention, and respiratory exchange rate independent of respiratory rate changes at rest, during, and/or following VH exercise protocol illustrates a rapid countermeasure to CO₂ retention in concert with systemic metabolic changes.

Transferable Benefits of Cycle Hypoventilation Training for Run-Based Performance in Team-Sport Athletes

PURPOSE

To determine whether high-intensity training with voluntary hypoventilation at low lung volume (VHL) in cycling could improve running performance in team-sport athletes.

METHODS

Twenty well-fit subjects competing in different team sports completed, over a 3-week period, 6 high-intensity training sessions in cycling (repeated 8-s exercise bouts at 150% of maximal aerobic power) either with VHL or with normal breathing conditions. Before (Pre) and after (Post) training, the subjects performed a repeated-sprint-ability test (RSA) in running (12 × 20-m all-out sprints), a 200-m maximal run, and the Yo-Yo Intermittent Recovery Level 1 test (YYIR1).

RESULTS

There was no difference between Pre and Post in the mean and best velocities reached in the RSA test, as well as in performance and maximal blood lactate concentration in the 200-m-run trial in both groups. On the other hand, performance was greater in the second part of the RSA test, and the fatigue index of this test was lower (5.18% [1.3%] vs 7.72% [1.6%]; P < .01) after the VHL intervention only. Performance was also greater in the YYIR1 in the VHL group (1468 [313] vs 1111 [248] m; P < .01), whereas no change occurred in the normal-breathing-condition group.

CONCLUSION

This study showed that performing high-intensity cycle training with VHL could improve RSA and possibly endurance performance in running. On the other hand, this kind of approach does not seem to induce transferable benefits for anaerobic performance.

Hold your breath: peripheral and cerebral oxygenation during dry static apnea

PURPOSE

Acute breath-holding deprives the human body from oxygen. In an effort to protect the brain, the diving response is initiated, coupling several physiological responses. The aim of this study was to describe the physiological responses to apnea at the cardiac, peripheral and cerebral level.

METHODS

31 physically active subjects (17 male, 14 female, 23.3 ± 1.8 years old) performed a maximal static breath-hold in a seated position. Heart rate (HR), muscle and cerebral oxygenation (by means of near-infrared spectroscopy, NIRS) were continuously measured. RM MANOVA's were used to identify changes in HR, peripheral (mTOI) and cerebral (cTOI) tissue oxygenation and oxygenated (O₂Hb) and deoxygenated (HHb) hemoglobin during apnea.

RESULTS

Average apnea duration was 157 ± 41 s. HR started decreasing after 10 s (p < 0.001) and dropped on average by 27 ± 14 bpm from baseline (p < 0.001). mTOI started decreasing 10 s after apnea (p < 0.001) and fell by 8.6 ± 4.0% (p < 0.001). Following an immediate drop after 5 s (p < 0.001), cTOI increased continuously, reaching a maximal increase of 3.7 ± 2.4% followed by a steady decrease until the end of apnea. cTOI fell on average 5.4 ± 8.3% below baseline (p < 0.001).

CONCLUSION

During apnea, the human body elicits several protective mechanisms to protect itself against the deprivation of oxygen. HR slows down, decreasing O₂ demand of the cardiac muscle. The decrease in mTOI and increase in cTOI imply a redistribution of blood flow prioritizing the brain. However, this mechanism is not sufficient to maintain cTOI until the end of apnea.

Impact of Hypoventilation Training on Muscle Oxygenation, Myoelectrical Changes, Systemic [K+], and Repeated-Sprint Ability in Basketball Players

This study investigated the impact of repeated-sprint (RS) training with voluntary hypoventilation at low lung volume (VHL) on RS ability (RSA) and on performance in a 30-15 intermittent fitness test (30-15_IFT). Over 4 weeks, 17 basketball players included eight sessions of straight-line running RS and RS with changes of direction into their usual training, performed either with normal breathing (CTL, n = 8) or with VHL (n = 9). Before and after the training, athletes completed a RSA test (12 × 30-m, 25-s rest) and a 30-15_IFT. During the RSA test, the fastest sprint (RSA_best), time-based percentage decrement score (RSA_Sdec), total electromyographic intensity (RMS), and spectrum frequency (MPF) of the biceps femoris and gastrocnemius muscles, and biceps femoris NIRS-derived oxygenation were assessed for every sprint. A capillary blood sample was also taken after the last sprint to analyse metabolic and ionic markers. Cohen's effect sizes (ES) were used to compare group differences. Compared with CTL, VHL did not clearly modify RSA_best, but likely lowered RSA_Sdec (VHL: −24.5% vs. CTL: −5.9%, group difference: −19.8%, ES −0.44). VHL also lowered the maximal deoxygenation induced by sprints ([HHb]_max; group difference: −2.9%, ES −0.72) and enhanced the reoxygenation during recovery periods ([HHb]_min; group difference: −3.6%, ES −1.00). VHL increased RMS (group difference: 18.2%, ES 1.28) and maintained MPF toward higher frequencies (group difference: 9.8 ± 5.0%, ES 1.40). These changes were concomitant with a lower potassium (K⁺) concentration (group difference: −17.5%, ES −0.67), and the lowering in [K⁺] was largely correlated with RSA_Sdec post-training in VHL only (r = 0.66, p < 0.05). However, VHL did not clearly alter PO₂, hemoglobin, lactate and bicarbonate concentration and base excess. There was no difference between group velocity gains for the 30-15_IFT (CTL: 6.9% vs. VHL: 7.5%, ES 0.07). These results indicate that RS training combined with VHL may improve RSA, which could be relevant to basketball player success. This gain may be attributed to greater muscle reoxygenation, enhanced muscle recruitment strategies, and improved K⁺ regulation to attenuate the development of muscle fatigue, especially in type-II muscle fibers.

An Updated Panorama of "Living Low-Training High" Altitude/Hypoxic Methods

With minimal costs and travel constraints for athletes, the “living low-training high” (LLTH) approach is becoming an important intervention for modern sport. The popularity of the LLTH model of altitude training is also associated with the fact that it only causes a slight disturbance to athletes' usual daily routine, allowing them to maintain their regular lifestyle in their home environment. In this perspective article, we discuss the evolving boundaries of the LLTH paradigm and its practical applications for athletes. Passive modalities include intermittent hypoxic exposure at rest (IHE) and Ischemic preconditioning (IPC). Active modalities use either local [blood flow restricted (BFR) exercise] and/or systemic hypoxia [continuous low-intensity training in hypoxia (CHT), interval hypoxic training (IHT), repeated-sprint training in hypoxia (RSH), sprint interval training in hypoxia (SIH) and resistance training in hypoxia (RTH)]. A combination of hypoxic methods targeting different attributes also represents an attractive solution. In conclusion, a growing number of LLTH altitude training methods exists that include the application of systemic and local hypoxia stimuli, or a combination of both, for performance enhancement in many disciplines.

A Physiological Overview of the Demands, Characteristics, and Adaptations of Highly Trained Artistic Swimmers: a Literature Review

Artistic swimming (AS) is a very unique sport consisting of difficult artistically choreographed routines ranging in the number of athletes (one to ten: solo, duet, team, combination, highlight routine) and with elements performed quickly and precisely above, below, and on the surface of the water. As a result, the physical and physiological demands placed on an athlete are unique to the sport with the most pronounced adaptation being the bradycardic response to long apneic periods spent underwater while performing strenuous movements. This indeed influences training prescription and the desired training outcomes. This review paper explores the physiological demands of AS, the physiological characteristics that influence AS performance, and innovative approaches to enhancing training and performance in elite performers.

Upper-body repeated-sprint training in hypoxia in international rugby union players

This study investigated the effects of upper-body repeated-sprint training in hypoxia vs. in normoxia on world-level male rugby union players' repeated-sprint ability (RSA) during an international competition period. Thirty-six players belonging to an international rugby union male national team performed over a 2-week period four sessions of double poling repeated-sprints (consisting of 3 × eight 10-s sprints with 20-s passive recovery) either in normobaric hypoxia (RSH, simulated altitude 3000 m, n = 18) or in normoxia (RSN, 300 m; n = 18). At pre- and post-training intervention, RSA was evaluated using a double-poling repeated-sprint test (6 × 10-s maximal sprint with 20-s passive recovery) performed in normoxia. Significant interaction effects (P < 0.05) between condition and time were found for RSA-related parameters. Compared to Pre-, peak power significantly improved at post- in RSH (423 ± 52 vs. 465 ± 69 W, P = 0.002, η²=0.12) but not in RSN (395 ± 65 vs. 397 ± 57 W). Averaged mean power was also significantly enhanced from pre- to post-intervention in RSH (351 ± 41 vs. 388 ± 53 W, P < 0.001, η²=0.15), while it remained unchanged in RSN (327 ± 49 vs. 327 ± 43 W). No significant change in sprint decrement (P = 0.151, η² = 0.02) was observed in RSH (-17 ± 2% vs. -16 ± 3%) nor RSN (-17 ± 2% vs. -18 ± 4%). This study showed that only four upper-body RSH sessions were beneficial in enhancing repeated power production in international rugby union players. Although the improvement from RSA to game behaviour remains unclear, this finding appears of practical relevance since only a short preparation window is available prior to international games.