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Physiological Responses to Exercise in Hypoxia: The Effect of Cold-Air Exposure and Sex Differences
Full text linkThe effects of acute hypoxic exposure on physiological responses during exercise have been extensively studied in recent decades, given the growing number of individuals engaging in high-altitude (HA) activities for both training and recreational purposes. Understanding the impact of reduced oxygen availability on the physiological mechanisms involved in exercise responses is crucial for enhancing human tolerance to HA, thereby mitigating the health risks associated with this extreme environment. However, real-world HA scenarios often involve multiple stressors, with one of the most common being extremely low ambient temperatures. Despite the prevalence of such conditions, there is a scarcity of specific studies investigating the interaction between cold and hypoxic effects on exercising responses. This is largely due to the experimental, temporal, and practical challenges associated with such approaches. Additionally, many studies exploring the effects of acute hypoxic exposure on exercise physiology have predominantly focused on male subjects. This limitation complicates the understanding of whether tailored interventions based on biological sex are necessary to ensure the safest high-altitude exposure for both men and women.
This doctoral thesis addresses these gaps by investigating the combined cold-hypoxic effects on whole-body exercise responses and examining the influence of biological sex on various aspects related to oxygen transportation within the organism at high altitudes. The research provides valuable insights into the intricate interaction between exercise and hypoxic stimuli while considering the real-world characteristics of HA exposure and its implications for all practitioners.
In particular, Study 1 explores the independent and combined effects of cold and hypoxia on maximal, submaximal, and lactate threshold responses in trained male subjects. The findings indicate that both cold and hypoxia independently impact exercising responses, with the combination of the two stressors exhibiting additive effects on the majority of considered outcomes.
Continuing from Study 1, Study 2 aims to investigate potential exacerbation effects of combined cold-hypoxic exposure on respiratory muscle fatigue (RMF) and exercise-induced bronchoconstriction (EIB). This study seeks to elucidate the relationship between exercising ventilatory responses and the pulmonary function and respiratory muscles work at simulated freezing altitudes. Results show that both respiratory muscle fatigue and exercise-induced bronchoconstriction are negatively affected by cold exposure, with no significant additional impairments related to the hypoxic stimulus, at least after high-intensity exercise of short duration.
Finally, study 3 compares ventilatory responses, lung diffusion capacity, and cardiovascular adaptations in trained men and women during exercise in hypoxia. Similar responses to exercise during simulated high-altitude exposure have been observed in both sexes, suggesting no influence of biological sex on the variations in the functioning of the examined systems when circulating oxygen availability is reduced.
This doctoral thesis and the data presented herein want to expand our understanding of hypoxic exercise and stimulate new research on this topic, minding the gap between experimental settings and real-world situations
Eager to set a record in a vertical race? Test your VO2max first!
No full textWe investigated the relationship between maximal oxygen consumption (VO2max) and performance in vertical races (VRs). In total, 270 performances, from 26 VRs, and cardiopulmonary data of 64 highly-trained mountain runners (53 M, V O-2max: 75.7 +/- 5.8 mL/min/kg; 11 F: 65.7 +/- 3.4 mL/min/kg), collected over a 11-year period (2012-2022), were analysed. The relationship between performance and VO2max was modelled separately for national (NVRs), international (IVRs), and VRs of current pole-unassisted and pole-assisted vertical kilometre (VK) records (RVRs). Three different (p<0.001) exponential models described the relationship between performance and VO2max in IVRs (R-2=0.96, p<0.001), NRs (R-2=0.91, p<0.001) and RVRs (R-2=0.97, p<0.001). Estimated VO2max requirements (with 95% CI) to win/set a record time in IVRs were 86.2(85.3-87.1)/89.4(88.2-90.5) and 74.0(73.6-74.4)/76.8(76.4-77.3) mL/min/kg, for males and females, respectively, 86.1(85.0-87.1)/90.4(89.0-91.8) and 74.8(74.2-75.3)/77.1(77.6-77.7) mL/min/kg in RVRs, decreasing to 83.7(82.5-84.9)/87.6(86.0-89.2) and 66.8(65.9-67.7)/70.7(70.1-71.4) mL/min/kg in NVRs. Our study also suggested a tendency towards a non-uniform variation in the metabolic demand of off-road running, likely attributable to the different features of the VRs (e.g., terrain, technical level, use of poles). These data provide mean VO2max requirements for mountain runners to win and establish new records in VRs and stimulate new research on the energy cost of off-road running
Combined effects of normobaric hypoxia and cold on respiratory system responses to high-intensity exercise
Full text linkCold temperatures (<-15°C) increase exercise-induced bronchoconstriction (EIB), while hypoxic-induced hyperventilation exacerbates respiratory muscle fatigue for a given exercising task. This study aimed to determine the individual and combined effects of cold and normobaric hypoxia on the respiratory system responses to high-intensity exercise. Fourteen trained male runners ( V̇O2max : 64 ± 5 mL/kg/min) randomly performed an incremental cardiopulmonary exercise test (CPET) to volitional exhaustion under four environmental conditions: normothermic (18°C) normoxia ( FIO2 : 20.9%) and hypoxia ( FIO2 : 13.5%), and cold (-20°C) normoxia and hypoxia. Ventilatory responses during exercise and lung function (LF), maximal inspiratory (MIP) and expiratory (MEP) pressure measurements before and after exercise were evaluated. Volume of air forcefully exhaled in 1 s (FEV1), FEV1/forced vital capacity (FVC), peak expiratory flow, forced expiratory flow during the mid (25-75%) portion of the FVC, and maximal expiratory flow at 50% of FVC were affected by cold exposure. No significant pre- to post-exercise change in MIP and MEP was found, independent of environmental conditions. Greater LF impairments in cold-normoxia and coldhypoxia were associated with the lowest peak ventilatory responses during exercise. Cold exposure was found to negatively impact peak ventilatory responses and post-exercise LF, further highlighting a relationship between EIB presence and the blunted ventilatory response in the cold. Respiratory muscle strength remained unchanged after exercise regardless of the environmental condition, suggesting no detrimental effect of hypoxia on this parameter when intermittent short-duration high-intensity exercises are performed. Future studies should investigate the combined cold-hypoxic effect on longer exercise durations at a sustained high intensity, accounting for differences between normobaric and hypobaric hypoxia exposures
Exercising at the time of the COVID-19 pandemic: acute physiological, perceptual and performance responses of wearing face masks during sports activity
Full text linkBackground: The COVID-19 pandemic requires the adoption of strict preventive measures, such as wearing a protective face mask , but few studies investigated its impact during exercise. We investigated the effects of wearing a protective face mask while exercising at different intensities and verified whether differences between two types of protective face masks exist. Methods: Twenty subjects performed 4-min running at 8 km•h-1 and at 10 km•h-1, 8 x 90-m Intermittent running bouts and the Yo-Yo Intermittent Recovery Test Level-1, while wearing either a surgical mask, a sports-reusable mask or no mask. Physiological responses (HR, [La], SpO2), overall and breathlessness perceived exertion and YYIRT1-distance were assessed. Results: Breathlessness RPE was greater with surgical than without mask at the end of the run at 8 km•h-1 (+7.18 [3.21, 11.50]) and with both surgical and sports-reusable mask than without mask at the end of the run at 10 km•h-1 (+8.09 [4.09, 12.60] and +8.21 [4.53, 12.70]) and intermittent exercise (+11.10 [6.41, 16.10] and +10.50 [6.18, 15.30]). Overall RPE was greater with surgical than without mask at the end of the run at 8 (+3.71 [1.15, 6.91]) and 10 km•h-1 (+5.29 [2.26, 8.85]). Furthermore, YYIRT1 performance was lower with surgical (-150 m [44, 240]) and sports-reusable mask (-201 m [108, 286]) than without mask. Conclusions: Regardless of exercise intensity and mask type, wearing a protective face mask mostly affects perceptual responses, also causing a performance reduction during maximal exercise. These findings must be considered when prescribing/practicing exercise while wearing a protective face mask
Analysis of sprint ski mountaineering performance
No full textSki mountaineering sprint competitions are short individual races involving 3 uphill sections (U), 3 transitions (T), and a final descent. To date, relatively little is known about this novel Olympic discipline, and here we examined (1) the contribution of the time spent on U, T, and final descent to overall finishing time and (2) the potential relationships with final ranking. During the different rounds of 2 International Ski Mountaineering Federation World Cup sprint competitions, male and female ski mountaineers were video recorded. Correlation and multiple linear regression analyses were used to investigate the impact of U, T, and final descent on the best overall finishing time. Linear-mixed model analysis was applied to explore potential interactions between section times, rounds, and final ranking. Overall, U (r = .90-.97) and T (r = .57-.89) were closely correlated with the best overall finishing time (all P < .05). U explained approximately 80% to 90% of the variation in the best finishing time for both sexes, with U + T explaining approximately 95% to 98% of this variation. In each successive round, the ski mountaineers eliminated were all slower on U than the Top 3 (all P < .05). The fastest skiers increased their performance on U in the later rounds of the competitions, while those eliminated showed a tendency toward a decrease. Our findings reveal that world-class sprint ski mountaineers conduct transitions optimally and perform effectively uphill. Training for such competitions should aim to improve short supramaximal uphill performance (∼1.5-2.5 min), ensuring that this does not decline with multiple efforts. These insights into ski mountaineering sprint performance are of considerable value in connection with training for the 2026 Winter Olympics
Participation and performance by women and men in ski-mountaineering sprint races during the past decade
No full textBackground: The sprint is one of the two ski-mountaineering disciplines that will be held at the coming Milano Cortina 2026 Winter Olympics (Italy). To date little information exists on this novel Olympic discipline. Methods: We characterized retrospectively the participation and performance in international male and female ski mountaineering sprint races from November 2012 to April 2022. Potential associations between sex and season with participation, as well as between sex, period, round and final ranking with parameters of performance were examined with linear-mixed models. Results: The minimal performance time required for success (i.e., being eligible for the next round/winning a medal) decreased progressively from the qualifications (Qs) to the final (F). Finalists adopted a conservative strategy in the Qs, improving their performance in the quarter-finals (QFs) and semifinals (SFs). The best and second-best male skier and the best female skier improved their performances even further in the F, which appears to be a key feature for success. For women, the number of participants and level of competition increased over the decade, whereas male participation did not. During the last two seasons, male sprint winners performed relatively more slowly in the preliminary rounds leaving more room for improvement in the F, which could reflect increased specialization in this discipline. Conclusions: Our findings provide novel insights into ski-mountaineering sprint races that can guide competition strategies and could be of considerable importance in connection with the Milano Cortina 2026 Winter Olympics (Italy)
Effects of three-exercise sessions in the heat on endurance cycling performance
Full text linkPurpose: To investigate the effects of a very short-term acclimation protocol (VSTAP) on performance, physiological and perceptual responses to exercise in the heat. Methods: 12 trained male cyclists (age 31.2 ± 7; weight 71.3 ± 7 kg, VO2max: 58.4 ± 3.7 mL/kg/min) randomly performed two Time to Exhaustion Tests (TTE) at 75% of normothermic peak power output (PPO), one in normothermia (N,18°C-50% RH) and one in the heat (H,35°C-50% RH), before and after a VSTAP intervention, consisting of 3 days-90 min exercise (10min at 30% of PPO+80 min at 50% of PPO) in H (≈4.5h of heat exposure). Performance time of TTEs and physiological and perceptual variables of both TTEs and training sessions (T1, T2 and T3) were evaluated. Results: Magnitude Based Inferences (MBI) revealed 92/6/1% and 62/27/11% chances of positive/trivial/negative effects of VSTAP of improving performance in H (+17%) and in N (+9%), respectively. Heart Rate (HR) decreased from T1 to T3 (p < 0.001) and T2 to T3 (p < 0.001), whereas Tympanic Temperature (TyT) decreased from T1 to T2 (p = 0.047) and from T1 to T3 (p = 0.007). Furthermore, despite the increased tolerance to target Power Output (PO) throughout training sessions, RPE decreased from T1 to T3 (p = 0.032). Conclusions: The VSTAP determined meaningful physiological (i.e. decreased HR and TyT) and perceptual (i.e. decreased RPE) adaptations to submaximal exercise. Furthermore, showing good chances to improve performance in the heat, it represents a valid acclimation strategy to be implemented when no longer acclimation period is possible. Finally, no cross-over effect of the VSTAP on performance in temperate conditions was detected
Competitive Demands and Performance-Determining Variables in Olympic Ski Mountaineering
No full textPurpose: To investigate the competitive demands and performance-determining variables in the Sprint and Mixed-Relay formats in male and female ski mountaineers. Methods: Performance data of 76 ski mountaineers (36 females) competing in a World Cup event were analyzed. A total of 20 ski mountaineers (11 females) completed ski-mountaineering-specific maximal and supramaximal (intensity > VO2max) tests, with a subgroup of 10 ski mountaineers (5 females) being monitored during the races. Results: Near-maximal cardiac responses (>95% of maximal heart rate) were observed in the 2 formats, with significantly higher ascent speed and contribution of lactic anaerobic metabolism in the Sprint than in the Mixed Relay (blood lactate 12.9 [3.2] vs 6.3 [1.2] mmol/L, P < .001). Uphill skiing represented the majority of race time in both formats and accounted for most of the variance in performance (∼80%-90%), with transition times explaining almost all the remaining variance (∼10%-15%). In the Mixed Relay, the skiing speed at the second ventilatory threshold (R2 = .78, P = .001) and the maximal speed at the end of the VO2max test (R2 = .78, P = .019) were the best predictors of performance in the whole pool of ski mountaineers and in males, respectively. The maximal sustainable skiing speed over a 2-minute effort was the best predictor of performance in the Sprint (R2 = .95, P < .001) for both sexes. Discussion: Ski mountaineers should tailor their training considering the specific physiological demands of each race, emphasizing near-maximal to maximal intensities for the Mixed Relay and supramaximal intensities for the Sprint. These insights into Olympic ski-mountaineering disciplines are of considerable value for athletes and coaches in preparation for the Winter Olympics
Immediate effects of sports massage on muscle strength, power and balance after simulated trail running in the cold
Full text linkPurpose
Despite the efficacy of sports massage as a recovery strategy is still debated and most research suggests minor effects, little is known about the potential effects on recovery after exercise in a cold environment.
Methods
A cross-sectional study was performed on 13 male trail runners (30 years, range 23–37) who ran on a treadmill inside a climatic chamber at 5 °C, for 15 min uphill (15%) at 40% of the maximum aerobic velocity (VAM), followed by 15 min downhill (− 15%) at 70% of the VAM. After the run, sports massage was performed on a randomized anterior and posterior thigh for 10 min total. Assessments were performed before the run (t0) and after the massage (t2), and results were compared with the non-treated lower limb, including single-leg isometric strength and jump, balance, skin temperature and pain.
Results
Sports massage was associated with increased anterior thigh skin temperature (p = 0.001, ηp2 = 0.455) and improved single-leg balance (p = 0.008, ηp2 = 0.452) and pain (p < 0.001, ηp2 = 0.509), whereas a non-significant effect was found for isometric strength and jump.
Conclusions
The results from this study suggest that sports massage performed in a cold environment after uphill–downhill running might reduce the effects of fatigue on balance and perceived pain and might be useful to promote recovery after strenuous exercise
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