Validation of Air Storage System for Hypoxia Exposure During Exercise.

Norberto, Matheus S., João Victor G. Torini, Matheus S. Firmino, and Marcelo Papoti. Validation of air storage system for hypoxia exposure during exercise. High Alt Med Biol. 00:000-000, 2024.-Considering the importance of optimizing normobaric hypoxia exposure (i.e., higher delivery capacity), the current study aims to validate a hypoxic air storage system. The study has a cross-over, one-blind randomized design. The air storage is composed of a piping system that directs hypoxic air from a hypoxia generator into nylon bags. Sixteen men (age, 25.4 ± 4.8 years; height, 174.9 ± 9.4 cm; weight, 77.1 ± 17.2 kg) performed three incremental treadmill tests until exhaustion on different days. For test-retest, the subjects repeated two tests in similar hypoxia conditions (H1 and H2; fraction of inspired O2 [FIO2] = ∼0.13; reliability analysis), and one time in normoxia (FIO2 = ∼0.20; condition comparison). Subjects' performance, blood lactate concentration ([La-]), arterial oxygen saturation (SpO2), oxygen consumption (VO2), heart rate (HR), and several respiratory-derived variables were evaluated. A comparison was made between the rest, moderate intensity, and exhaustion stages. All variables were compared using the Friedman test with Durbin-Conover post hoc (p < 0.05). The hypoxia test-retest showed no statistical differences for any variable. Time analysis showed similar behavior for SpO2, HR, and cardiorespiratory variables (p < 0.01) for both conditions. The mean FIO2 at rest and during the incremental treadmill test was higher for normoxia (20.6 ± 0.2%) than for H1 (13.8 ± 0.8%) and H2 (13.7 ± 0.3%) (p < 0.001). The VO2 response was higher in normoxia than during hypoxia exposure at moderate intensity (Normoxia = 43.1 ± 8.1; H1 = 38.7 ± 5.7; H2 = 35.8 ± 8.8 ml.kg-1.min-1) and at the exhaustion stage (Normoxia = 52.7 ± 12.5; H1 = 41.9 ± 8.8; H2 = 40.5 ± 8.9 ml.kg-1.min-1) (p < 0.01). SpO2 and HR showed excellent intraclass correlation coefficient (ICC) during all moments, whereas VO2, SpO2, ratio between ventilation and CO2 production (VE/VCO2), ratio between oxygen consumption and ventilation (VE/VO2), and HR showed moderate or good ICC and coefficient of variation <9% during hypoxia test-retest exercises. Thus, the air storage system showed validity for its application and reliability in the measurements associated.

Inspiratory muscles pre-activation in young swimmers submitted to a tethered swimming test: effects on mechanical, physiological, and skin temperature parameters.

Inspiratory muscles pre-activation (IMPA) has been studied to improve subsequent performance in swimming. However, the effects of IMPA on various parameters in swimmers are still unknown. Therefore, this study aimed to investigate the effects of IMPA on the mechanical parameters, physiological responses, and their possible correlations with swimming performance. A total of 14 young swimmers (aged 16 ± 0 years) underwent a 30-s all-out tethered swimming test, preceded or not by IMPA, a load of 40% of the maximal inspiratory pressure (MIP), and with a volume of 2 sets of 15 repetitions. The mechanical (strength, impulse, and fatigue index) and physiological parameters (skin temperature and lactatemia) and the assessment of perceived exertion and dyspnea were monitored in both protocols. The IMPA used did not increase the swimming force, and skin temperature, decrease blood lactate concentration, or subjective perception of exertion and dyspnea after the high-intensity tethered swimming exercises. Positive correlations were found between mean force and blood lactate (without IMPA: r = 0.62, P = 0.02; with IMPA: r = 0.65, P = 0.01). The impulse was positively correlated with blood lactate (without IMPA: r = 0.71, P < 0.01; with IMPA: r = 0.56, P = 0.03). Our results suggest that new IMPA protocols, possibly with increased volume, should be developed in order to improve the performance of young swimmers.

Four-week experimental plus 1-week taper period using live high train low does not alter muscle glycogen content.

This study aimed to investigate the effects of a 4-week live high train low (LHTL; FiO2 ~ 13.5%), intervention, followed by a tapering phase, on muscle glycogen concentration. Fourteen physically active males (28 ± 6 years, 81.6 ± 15.4 kg, 179 ± 5.2 cm) were divided into a control group (CON; n = 5), and the group that performed the LHTL, which was exposed to hypoxia (LHTL; n = 9). The subjects trained using a one-legged knee extension exercise, which enabled four experimental conditions: leg training in hypoxia (TLHYP); leg control in hypoxia (CLHYP, n = 9); leg trained in normoxia (TLNOR, n = 5), and leg control in normoxia (CLNOR, n = 5). All participants performed 18 training sessions lasting between 20 and 45 min [80-200% of intensity corresponding to the time to exhaustion (TTE) reached in the graded exercise test]. Additionally, participants spent approximately 10 h day-1 in either a normobaric hypoxic environment (14.5% FiO2; ~ 3000 m) or a control condition (i.e., staying in similar tents on ~ 530 m). Thereafter, participants underwent a taper protocol consisting of six additional training sessions with a reduced training load. SpO2 was lower, and the hypoxic dose was higher in LHTL compared to CON (p < 0.001). After 4 weeks, glycogen had increased significantly only in the TLNOR and TLHYP groups and remained elevated after the taper (p < 0.016). Time to exhaustion in the LHTL increased after both the 4-week training period and the taper compared to the baseline (p < 0.001). Although the 4-week training promoted substantial increases in muscle glycogen content, TTE increased in LHTL condition.

Use of Inter-Effort Recovery Hypoxia as a New Approach to Improve Anaerobic Capacity and Time to Exhaustion.

Putti, Germano Marcolino, Gabriel Peinado Costa, Matheus Silva Norberto, Carlos Dellavechia de Carvalho, Rômulo Cássio de Moraes Bertuzzi, and Marcelo Papoti. Use of inter-effort recovery hypoxia as a new approach to improve anaerobic capacity and time to exhaustion. High Alt Med Biol. 25:68-76, 2024. Background: Although adding hypoxia to high-intensity training may offer some benefits, a significant problem of this training model is the diminished quality of the training session when performing efforts in hypoxia. The purpose of this study was to investigate the effects of training and tapering combined with inter-effort recovery hypoxia (IEH) on anaerobic capacity, as estimated by alternative maximum accumulated oxygen deficit (MAODALT) and time to exhaustion (TTE). Methods: Twenty-four amateur runners performed, for 5 weeks, 3 sessions per week of training consisted of ten 1-minute bouts at 120% (weeks 1-3) and 130% (weeks 4 and 5) of maximum velocity (VMAX) obtained in graded exercise test, separated by a 2-minute interval in IEH (IEH, n = 11, FIO2 = 0.136) or normoxia (NOR, n = 13, fraction of inspired oxygen = 0.209). Before training, after training, and after 1 week of tapering, a graded exercise test and a maximal effort to exhaustion at 120% of VMAX were performed to determine TTE and MAODALT. The results were analyzed using generalized linear mixed models, and a clinical analysis was also realized by the smallest worthwhile change. Results: MAODALT increased only in IEH after training (0.8 ± 0.5 eq.lO2) and tapering (0.8 ± 0.5 eq.lO2), with time x group interaction. TTE increased for the pooled groups after taper (23 ± 11 seconds) and only for IEH alone (29 ± 16 seconds). Clinical analysis revealed a small size increase for NOR and a moderate size increase for IEH. Conclusions: Although the effects should be investigated in other populations, it can be concluded that IEH is a promising model for improving anaerobic performance and capacity. World Health Organization Universal Trial Number: U1111-1295-9954. University's ethics committee registration number: CAAE: 32220020.0.0000.5659.

Reliability of Anaerobic Contributions during a Single Exhaustive Knee-extensor Exercise.

The total anaerobic contribution (AC[La-]+PCr) is a valid and reliable methodology. However, the active muscle mass plays an important role in the AC[La-]+PCr determination, which might influence its reliability. Thus, this study aimed to investigate the effects of two exhaustive intensities on the reliability of the AC[La-]+PCr during a one-legged knee extension (1L-KE) exercise. Thirteen physically active males were submitted to a graded exercise to determine the peak power output (PPO) in the 1L-KE. Then, two constant-load exercises were conducted to task failure at 100% (TTF100) and 110% (TTF110) of PPO, and the exercises were repeated on a third day. The blood lactate accumulation and the oxygen uptake after exercise were used to estimate the anaerobic lactic and alactic contributions, respectively. Higher values of AC[La-]+PCr were found after the TTF100 compared to TTF110 (p=0.042). In addition, no significant differences (p=0.432), low systematic error (80.9 mL), and a significant ICC (0.71; p=0.004) were found for AC[La-]+PCr in the TTF100. However, an elevated coefficient of variation was found (13.7%). In conclusion, we suggest the use of the exhaustive efforts performed at 100% of the PPO with the 1L-KE model, but its elevated individual variability must be carefully considered in future studies.

Acute and cumulative effects of hypoxia exposure in people with Parkinson's disease: A scoping review and evidence map.

Hypoxia exposure may promote neuroprotection for people with Parkinson's disease (PwPD). However, to implement hypoxia in practical settings and direct future research, it is necessary to organize the current knowledge about hypoxia responses/effects in PwPD. Thus, the present scoping review elucidates the evidence about hypoxia exposure applied to PwPD. Following the PRISMA Extension for Scoping Reviews, papers were searched in PubMed/NCBI, Web of Science, and Scopus (descriptors: Parkinson and hypoxia, mountain, or altitude). We included original articles published in English until August 12, 2023. Eight studies enrolled participants with early to moderate stages of disease. Acute responses demonstrated that PwPD exposed to normobaric hypoxia presented lower hypoxia ventilatory responses (HVR), perceptions of dyspnea, and sympathetic activations. Cumulative exposure to hypobaric hypoxia (living high; 7 days; altitude not reported) induced positive effects on motor symptoms (hypokinesia) and perceptions of PwPD (quality of life and living with illness). Normobaric hypoxia (isocapnic rebreathe, 14 days, three times/day of 5-7 min at 8-10 % of O2) improved HVR. The included studies reported no harmful effects. Although these results demonstrate the effectiveness and safety of hypoxia exposure applied to PwPD, we also discuss the methodological limitations of the selected experimental design (no randomized controlled trials), the characterization of the hypoxia doses, and the range of symptoms investigated. Thus, despite the safety of both normobaric hypoxia and hypobaric hypoxia for early to moderate levels of disease, the current literature is still incipient, limiting the use of hypoxia exposure in practical settings.

3-min All-out Test to Evaluate Aerobic and Anaerobic Indexes in Court Team Sports.

This study aimed to test the reproducibility of the 3-min all-out effort applied using shuttle running and compare its values to aerobic parameters. On the first day, 14 futsal players underwent an exhaustive test to determine the maximal incremental speed (MIS) and anaerobic threshold (AnT). On the second day, the participants performed the 3-min all-out effort (n=14), which was repeated after 48 h (third day) to test its reproducibility (n=11). Peak oxygen consumption (V̇ O2PEAK) and peak blood lactate concentrations ([La-]) were determined from 3-min all-out efforts performed through a 20-m shuttle run on the official court. The distance covered, mean speed, and critical speed (CS) during the 3-min all-out presented direct relationships with aerobic parameters determined through the incremental test (r>0.62). The distance covered above CS (D') presented a direct relationship with peak lactate concentrations induced by a 3-min all-out effort (r=0.81). Despite the acceptable levels of reproducibility observed for most of the 3-min all-out variables, the minimal detectable change for D' was high (72%). Our results demonstrated the potential use of mean speed to evaluate aerobic fitness. However, the applicability of the 3-min all-out shuttle run test to monitor training adaptations should be avoided, at least in nonexperienced athletes.

Acute physiological responses to "recovery intermittent hypoxia" in hiit / Respuestas agudas a la "hipoxia intermitente de recuperación" en el hiit / Respostas fisiológicas agudas à "hipóxia intermitente de recuperação" no hiit

ABSTRACT Introduction: Traditional intermittent hypoxia training improves sport performance after short periods of exposure, but acute exposure to intermittent hypoxia leads to decreased training intensity and technical quality. The solution to overcome these negative effects may be to perform efforts in normoxia and the intervals between efforts in hypoxia, maintaining the quality of training and the benefits of hypoxia. Objective: This study aimed to evaluate the acute physiological responses to hypoxia exposure during recovery between high intensity efforts. Materials and methods: Randomized, one-blind, placebo-controlled study. Sixteen men performed a graded exercise test to determine their maximal intensity and two sessions of high-intensity interval training. The training intervals could be in hypoxia (HRT), FIO2: 0.136 or normoxia (NRT), FIO2: 0.209. During the two-minute interval between the ten one-minute efforts, peripheral oxygen saturation (SpO2), heart rate (HR), blood lactate ([La]), blood glucose ([Glu]) were constantly measured. Results: There were differences in HR (TRN = 120 ± 14 bpm; TRH = 129 ± 13 bpm, p < 0.01) and SpO2 (TRN = 96.9 ± 1.0%; TRH = 86.2 ± 3.5%, p < 0.01). No differences in [La] and [Glu] TRN (4.4 ± 1.7 mmol.l-1; 3.9 ± 0.5 mmol.l-1) and TRH (5.2 ± 2.0 mmol.l-1; 4.0 ± 0.8 mmol.l-1, p = 0.17). Conclusion: The possibility of including hypoxia only in the recovery intervals as an additional stimulus to the training, without decreasing the quality of the training, was evidenced. Level of Evidence II; Randomized Clinical Trial of Minor Quality.

RESUMEN Introducción: El entrenamiento tradicional en hipoxia intermitente mejora el rendimiento deportivo tras cortos periodos de exposición, sin embargo, la exposición aguda a la hipoxia intermitente conduce a una disminución de la intensidad del entrenamiento y de la calidad técnica. La solución para superar estos efectos negativos puede ser realizar los esfuerzos en normoxia y los intervalos entre esfuerzos en hipoxia, manteniendo la calidad del entrenamiento y los beneficios de la hipoxia. Objetivo: Este estudio pretendía evaluar las respuestas fisiológicas agudas a la exposición a la hipoxia durante la recuperación entre esfuerzos de alta intensidad. Materiales y métodos: Estudio aleatorizado, a ciegas y controlado con placebo. Dieciséis hombres realizaron una prueba de ejercicio graduado para determinar su intensidad máxima y dos sesiones de entrenamiento por intervalos de alta intensidad. Los intervalos de entrenamiento podían ser en hipoxia (HRT), FIO2: 0,136 o normoxia (NRT), FIO2: 0,209. Durante el intervalo de dos minutos entre los diez esfuerzos de un minuto, se midieron constantemente la saturación periférica de oxígeno (SpO2), la frecuencia cardiaca (FC), el lactato en sangre ([La]) y la glucemia ([Glu]). Resultados: Hubo diferencias en la FC (TRN = 120 ± 14 lpm; TRH = 129 ± 13 lpm, p < 0,01) y la SpO2 (TRN = 96,9 ± 1,0%; TRH = 86,2 ± 3,5%, p < 0,01). No hubo diferencias en [La] y [Glu] TRN (4,4 ± 1,7 mmol.l-1; 3,9 ± 0,5 mmol.l-1) y TRH (5,2 ± 2,0 mmol.l-1; 4,0 ± 0,8 mmol.l-1, p = 0,17). Conclusión: Se evidenció la posibilidad de incluir hipoxia sólo en los intervalos de recuperación como estímulo adicional al entrenamiento sin disminuir la calidad del mismo. Nivel de Evidencia II; Ensayo Clínico Aleatorizado de Baja Calidad.

RESUMO Introdução: O treinamento de hipóxia intermitente tradicional melhora o desempenho esportivo após curtos períodos de exposição, porém a exposição aguda à hipóxia intermitente leva à diminuição da intensidade do treinamento e da qualidade técnica. A solução para superar esses efeitos negativos pode ser realizar esforços em normóxia e os intervalos entre os esforços em hipóxia, mantendo a qualidade do treinamento e os benefícios da hipóxia. Objetivo: Este estudo teve como objetivo avaliar as respostas fisiológicas agudas à exposição de hipóxia durante a recuperação entre esforços de alta intensidade. Materiais e métodos: Estudo aleatório e one-blinded, com efeito placebo controlado. Dezesseis homens realizaram um teste de exercício graduado para determinar sua intensidade máxima e duas sessões de treinamento intervalado de alta intensidade. Os intervalos de treinamento podem ser em hipóxia (TRH), FIO2: 0,136 ou normóxia (TRN), FIO2: 0,209. Durante os dois minutos de intervalo entre os dez esforços de um minuto, foram medidos constantemente a saturação periférica de oxigênio (SpO2), frequência cardíaca (FC), lactato sanguíneo ([La]), glicemia ([Glu]). Resultados: Houve diferenças na FC (TRN = 120 ± 14 bpm; TRH = 129 ± 13 bpm, p <0,01) e SpO2 (TRN = 96,9 ± 1,0%; TRH = 86,2 ± 3,5%, p <0,01). Sem diferenças em [La] e [Glu] TRN (4,4 ± 1,7 mmol.l-1; 3,9 ± 0,5 mmol.l-1) e TRH (5,2 ± 2,0 mmol.l-1; 4,0 ± 0,8 mmol.l-1, p = 0,17). Conclusão: Evidenciou-se a possibilidade de incluir a hipóxia apenas nos intervalos de recuperação como um estímulo adicional ao treinamento, sem diminuir a qualidade do treinamento. Nível de Evidência II; Estudo Clínico Randomizado de Menor Qualidade.

Inter-effort recovery hypoxia: a new paradigm in sport science?

High-intensity interval training (HIIT) is a popular method for optimising sports performance and, more recently, improving health-related parameters. The inclusion of hypoxia during HIIT can promote additional gains compared with normoxia. However, reductions in the effort intensities compared with the same training performed in normoxia have been reported. Studies have reported that adding hypoxia during periods of inter-effort recovery (IEH) enables maintenance of the intensity of efforts. It also promotes additional gains from exposure to hypoxia. Our call is for researchers to consider IEH in experiments involving different models of HIIT. Additionally, we consider the need to answer the following questions: What is the clinically relevant minimum dose of exposure to hypoxia during the recovery periods between efforts so that favourable adaptations of parameters are associated with health and sports performance? How does the intensity of exertion influence the responses to hypoxia exposure during recovery periods? What are the chronic effects of different models of HIIT and hypoxia recovery on sports performance?

The Percentage of Total and Regional Fat Is Negatively Correlated with Performance in Judo.

This study investigated the associations between total and regional body composition with performance in the special judo fitness test (SJFT), as well as strength and power tests (countermovement vertical jump-CMJ, squat jump-SJ, plyometric push-up-PPU, and force push-up-FPU). Twenty-three high-level judo athletes participated in this study. Initially, they underwent dual-energy X-ray absorptiometry, after which they performed the CMJ, SJ, PPU, and FPU tests. On another day, the SJFT was carried out. Correlations were tested using Pearson's test. The performance in the SJFT was correlated with the total and arm %fat mass (r = -0.759), torso fat mass (r = -0.802), torso %fat mass (r = -0.822) and in the lower limb regions with the leg fat mass (r = -0.803) and leg %fat (r = -0.745). In the strength and power tests, there were also negative correlations observed between regional fat and performance. There was a negative correlation between the percentage of total fat and performance in the SJFT (r = -0.824), SJ (r = -0.750), CMJ (r = -0.742), PPU (r = -0.609), and FPU (r = -0.736). Fat, both total fat and regional fat in the arms, torso, and legs, is strongly correlated with a poor performance in the SJFT and poor strength and power.

Influence of photobiomodulation therapy on the physical performance of women during the follicular phase of the menstrual cycle: A double-blind Sham-controlled randomized clinical trial.

To evaluate the effects of photobiomodulation on the physical performance of healthy women, considering the menstrual cycle. 27 physically active healthy women (age 25.68 ± 3.99 years; mass 63.76 ± 12.77 kg; height 1.65 ± 0.59 cm) during the initial follicular phase (FF1 and FF2) of the menstrual cycle underwent performance evaluations, through a supramaximal test, subjective perception of exertion, blood lactate, and evaluations in the isokinetic dynamometer. Photobiomodulation (PBM) (200J) and Sham (0J) therapy were applied 10 min before the performance evaluations on the quadriceps femoris, hamstrings, and triceps surae muscles. A significance level of 5% was adopted and the effect size was calculated by Cohen's d. It was not possible to observe a significant difference (p > 0.05) in any of the performance variables evaluated in the comparison between groups, only small effects for total distance, final subjective perception of exertion, lactate peak and lactate delta in the PBM group. PBM did not improve muscle performance, resistance to fatigue, perceived exertion, and blood lactate concentrations during a predominantly anaerobic test in healthy women during the FF of the menstrual cycle.

Two Different Approaches to Dry-land Training Do Not Improve the Water Performance of Swimmers.

Literature diverges about the performance improvement after dry-land training. Thus, the objective of the present study was to compare the effect of two models of dry-land training. Twenty-nine swimmers were divided into three groups, combined strength and power training (PTG), only strength training (STG), and a control group (CG). Measurements were taken for six weeks, before dry-land exposure (M1), after four weeks of specific training with exposure to dry-land training by two groups (M2), and after two weeks of taper without exposure to dry-land training (M3). Strength in specific exercises, jumping tests, and 50, 100, and 200m freestyle performance were evaluated on M1 and M3, while hematological and strength parameters in tethered swimming were measured in M1, M2, and M3. PTG showed time-effect improvement for 200, 100, and 50m performance (p<0.014), CG for 200 and 100m (p<0.047), and STG only for 100m (p:0.01). No differences were found in Δ performance between groups. PTG showed improvement in the peak force of tethered swimming on M2 (p:0.019), followed by a decrease on M3 (p:0.003). PTG and STG also showed an increase in creatinine, lactate dehydrogenase (LDH), and creatine kinase (CK) after M2 (p<0.038). Finally, it was concluded that both dry-land training sessions could change hematological parameters and improve physical attributes on dry-land and tethered swimming tests without improving performance.

Living high - training low model applied to C57BL/6J mice: Effects on physiological parameters related to aerobic fitness and acid-base balance.

There is a scarcity of data regarding the acclimation to high altitude (hypoxic environment) accompanied by training at low altitude (normoxic conditions), the so-called "living high-training low" (LHTL) model in rodents. We aimed to investigate the effects of aerobic training on C57BL/6J mice living in normoxic (NOR) or hypoxic (HYP) environments on several parameters, including critical velocity (CV), a parameter regarded as a measure of aerobic capacity, on monocarboxylate transporters (MCTs) in muscles and hypothalamus, as well as on hematological parameters and body temperature. In each environment, mice were divided into non-trained (N) and trained (T). Forty rodents were distributed into the following experimental groups (N-NOR; T-NOR; N-HYP and T-HYP). HYP groups were in a normobaric tent where oxygen-depleted air was pumped from a hypoxia generator set an inspired oxygen fraction [FiO2] of 14.5 %. The HYP-groups were kept (18 h per day) in a normobaric tent for consecutive 8-weeks. Training sessions were conducted in normoxic conditions ([FiO2] = 19.5 %), 5 times per week (40 min per session) at intensity equivalent to 80 % of CV. In summary, eight weeks of LHTL did not promote a greater improvement in the CV, protein expression of MCTs in different tissues when compared to the application of training alone. The LHTL model increased red blood cells count, but reduced hemoglobin per erythrocyte was found in mice exposed to LHTL. Although the LHTL did not have a major effect on thermographic records, exercise-induced hyperthermia (in the head) was attenuated in HYP groups when compared to NOR groups.

Effects of Training and Taper on Neuromuscular Fatigue Profile on 100-m Swimming Performance.

This study aimed to investigate the effects of 6-week specific preparatory period and 2-week taper period on neuromuscular fatigue profile in 100-m front crawl swimming performance. Seventeen competitive-level young-adult swimmers performed a 100-m swimming performance at baseline and after 6-week specific preparatory followed by 2-week taper periods. Neuromuscular fatigue profile was assessed through percutaneous electrical stimuli on the femoral nerve during a maximal voluntary contraction performed before and immediately after each 100-m maximal effort. Performance improved (p=0.001) 2.24 and 3.06% after specific and taper, respectively. Potentiated peak force at post-effort condition decreased (p<0.001) 16.26% at baseline, 11.70% at specific, and 12.86% at taper period. Maximal voluntary contraction force also decreased (p<0.001) at post-effort condition by about 6.77 and 9.33% at baseline and specific period, respectively. Both variables did not present significant differences between times. No condition or time effects were observed to superimposed peak force and voluntary activation, both related to central fatigue. In conclusion, neuromuscular fatigue during 100-m swimming performance was exclusively developed by peripheral mechanisms regardless of the training period, and 2-week taper was able to prevent decreases in maximal voluntary contraction induced by 100-m maximal effort.

Can Hypoxia Alter the Anaerobic Capacity Measured by a Single Exhaustive Exercise?

The present study aimed to compare the MAODALT in situations of hypoxia and normoxia to confirm the method validity. Seventeen healthy and physically active men participated in this study, aged 25.2±3.2 years. All participants underwent four days of evaluation. The first day was performed a body composition test, an incremental test to exhaustion to determine the maximum oxygen uptake, familiarizing the hypoxia (H) and normoxia (N) situation and the equipment used. On the second, third and fourth days, supramaximal efforts were performed until exhaustion at 110% of maximum oxygen uptake, in a situation of hypoxia (FIO2=14.0%) and normoxia (FIO2=20.9%). The anaerobic capacity was considered the sum of energy supply of the alactic and lactic systens. The absolute or relative anaerobic capacity values were not different (H=3.9±1.1 L, N=3.8±0.9 L, p=0.69), similarly no differences were found for the alactic contribution (H=1.7±0.5 L, N=1.5±0.5 L, p=0.30) and lactic contribution (H=2.3±0.9 L, N=2.3±0.7 L, p=0.85). It can be concluded that the anaerobic capacity measured by a single exhaustive effort is not altered by hypoxia.

Effects of Moderate-Intensity Training Under Cyclic Hypoxia on Cardiorespiratory Fitness and Hematological Parameters in People Recovered From COVID-19: The AEROBICOVID Study.

BACKGROUND: Recent studies have indicated that people who live at altitude have a lower incidence of coronavirus disease (COVID-19) and lesser severity in infection cases. HYPOTHESIS: Hypoxia exposure could lead to health benefits, and it could be used in the recovery process as an additional stimulus to physical training to improve cardiorespiratory fitness (CRF). STUDY DESIGN: Randomized controlled clinical trial. LEVEL OF EVIDENCE: Level 2. METHODS: The 43 participants, aged 30 to 69 years, were divided into control group (CG, n = 18) and 2 training groups: normoxia (NG, n = 9) and hypoxia (HG, n = 16). Before and after the intervention were evaluated the lactate threshold 2 (L2), peak oxygen uptake (VO2peak), and a blood sample was collected at rest to evaluate hematological adaptation. Both groups performed an 8-week moderate-intensity physical training on a bike. The HG were trained under normobaric hypoxic conditions (fractional inspired oxygen [FiO2] = 13.5%). RESULTS: The 8-week intervention promoted a similar improvement in CRF of people recovered from COVID-19 in the HG (L2 = 34.6%; VO2peak = 16.3%; VO2peak intensity = 24.6%) and NG (L2 = 42.6%; VO2peak = 16.7%; VO2peak intensity = 36.9%). Only the HG presented differences in hematological variables (erythropoietin = 191.7%; reticulocytes = -32.4%; off-score = 28.2%) in comparison with the baseline. CONCLUSION: The results of the present study provide evidence that moderate-intensity training in normoxia or hypoxia promoted similar benefits in CRF of people recovered from COVID-19. Furthermore, the hypoxia offered an additional stimulus to training promoting erythropoietin increase and hematological stimulation. CLINICAL RELEVANCE: The present exercise protocol can be used for the rehabilitation of people recovered from COVID-19, with persistent low CRF. In addition, this is the first study demonstrating that physical training combined with hypoxia, as well as improving CRF, promotes greater hematological stimulation in people recovered from COVID-19.

Interaction predictors of self-perception menstrual symptoms and influence of the menstrual cycle on physical performance of physically active women.

OBJECTIVE: To analyze the physical performance, self-perception menstrual symptoms, of physically active eumenorrheic women with endogenous ovarian cycle in two phases of the menstrual cycle. METHODS: Twenty-six women participated in the study (age 25.8 ± 3.9 years; height 1.64 ± 0.58 m; mass 64 ± 12.32 kg; menarche 11.69 ± 1.28 years). Assessments were performed in two phases of the menstrual cycle (MC), Early-Follicular Phase (FP) and Mid-Luteal Phase (LP), performance was assessed through total time to exhaustion (TTE), complete stages (CE), and final speed (FE), through a graded exercise test (GXT). Information on the participants' menstrual symptoms and their perceptions of the influence of MC on their performance were also collected. Data normality was assessed using the Shapiro-Wilk test. Paired analyses were conducted (t test or Wilcoxon) to examine the responses between the menstrual phases. The interaction analysis of symptom predictors was performed by multiple linear regression, with a significance level of p ≤ 0.05. RESULTS: There was no significant difference in physical performance between the phases during the GXT in TTE (mean difference 8.50; 95% CI - 11.99 to 42; p = 0.36). During FP, women with heavy flow had shorter performance in the GXT (t = - 2.5; p = 0.01), demonstrating an r2 = 0.32. In LP, for the women who reported not having the perception of the influence of the menstrual cycle on exercise, the total test time was longer (t = 2.55; p = 0.01), with an r2 = 0.45. CONCLUSION: There was no difference in physical performance between FP and LP. However, menstrual flow intensity and perception of cycle interference demonstrated a decrease in TTE.

Effectiveness, implementation, and monitoring variables of intermittent hypoxic bicycle training in patients recovered from COVID-19: The AEROBICOVID study.

Hypoxic exposure is safely associated with exercise for many pathological conditions, providing additional effects on health outcomes. COVID-19 is a new disease, so the physiological repercussions caused by exercise in affected patients and the safety of exposure to hypoxia in these conditions are still unknown. Due to the effects of the disease on the respiratory system and following the sequence of AEROBICOVID research work, this study aimed to evaluate the effectiveness, tolerance and acute safety of 24 bicycle training sessions performed under intermittent hypoxic conditions through analysis of peripheral oxyhemoglobin saturation (SpO2), heart rate (HR), rate of perceived exertion (RPE), blood lactate concentration ([La-]) and symptoms of acute mountain sickness in patients recovered from COVID-19. Participants were allocated to three training groups: the normoxia group (GN) remained in normoxia (inspired fraction of O2 (FiO2) of ∼20.9%, a city with 526 m altitude) for the entire session; the recovery hypoxia group (GHR) was exposed to hypoxia (FiO2 ∼13.5%, corresponding to 3,000 m altitude) all the time except during the effort; the hypoxia group (GH) trained in hypoxia (FiO2 ∼13.5%) throughout the session. The altitude simulation effectively reduced SpO2 mean with significant differences between groups GN, GHR, and GH, being 96.9(1.6), 95.1(3.1), and 87.7(6.5), respectively. Additionally, the proposed exercise and hypoxic stimulus was well-tolerated, since 93% of participants showed no or moderate acute mountain sickness symptoms; maintained nearly 80% of sets at target heart rate; and most frequently reporting session intensity as an RPE of "3" (moderate). The internal load calculation, analyzed through training impulse (TRIMP), calculated using HR [TRIMPHR = HR * training volume (min)] and RPE [TRIMPRPE = RPE * training volume (min)], showed no significant difference between groups. The current strategy effectively promoted the altitude simulation and monitoring variables, being well-tolerated and safely acute exposure, as the low Lake Louise scores and the stable HR, SpO2, and RPE values showed during the sessions.

Comparison between low, moderate, and high intensity aerobic training with equalized loads on biomarkers and performance in rats.

This study investigated the physiological and molecular responses of Wistar Hannover rats, submitted to three 5-week chronic training models, with similar training loads. Twenty-four Wistar Hanover rats were randomly divided into four groups: control (n = 6), low-intensity training (Z1; n = 6), moderate-intensity training (Z2; n = 6) and high-intensity training (Z3; n = 6). The three exercise groups performed a 5-week running training three times a week, with the same prescribed workload but the intensity and the volume were different between groups. An increase in maximal speed was observed after four weeks of training for the three groups that trained, with no difference between groups. Higher rest glycogen was also observed in the soleus muscle after training for the exercise groups compared to the control group. We also found that the Z2 group had a higher protein content of total and phosphorylated GSK3-ß compared to the control group after five weeks of training. In conclusion, the present study shows that five weeks of treadmill training based on intensity zones 1, 2, and 3 improved performance and increased resting glycogen in the soleus muscle, therefore intensity modulation does not change the training program adaptation since the different program loads are equalized.

Physical activity in the post-COVID-19: AEROBICOVID project design and perspectives / Atividade física no pós-COVID-19: escopo do projeto AEROBICOVID e suas perspectivas

During the COVID-19 pandemic, several late-onset impairments have been observed, affecting the health and functionality of those involved. On the other hand, lower SARS-CoV-2 infection rates and severity of symptoms were observed in high-altitude cities. In this sense, the AEROBICOVID project was developed with the hypothesis that exercise would be an important opportunity for health improvement and that hypoxia would promote additional benefits in the recovery process. The cohort was about 84 participants with approximately 30 days since the COVID-19 symptoms recovery, 25 in the control group, and 59 divided into three moderate physical training groups. The project had good results in teaching, research, and extension, but also faced difficulties in operationalization. This experience is the basis for future proposals through an extension project at the University of São Paulo and in a Family Health Unit, besides a research project that will develop a new low-cost hypoxia technology (AU)

Durante a pandemia de COVID-19 estão sendo observados vários efeitos tardios, afetando a saúde e a funcionalidade dos acometidos. Por outro lado, foram observadas menores taxas de infecção pelo SARS-CoV-2 e gravidade dos sintomas em cidades de elevada altitude. Neste sentido, o projeto AEROBICOVID foi desenvolvido com a hipótese de que o exercício seria uma proposta importante para a melhoria da saúde e que a hipóxia promoveria benefícios adicionais no processo de recuperação. Participaram 84 pessoas com aproximadamente 30 dias desde a recuperação dos sintomas da COVID-19, 25 no grupo de controle e 59 divididos em três grupos de treinamento físico moderado. O projeto teve bons resultados no ensino, pesquisa e extensão, mas também enfrentou dificuldades na operacionalização. Estas experiências são a base para propostas futuras através de um projeto de extensão na Universidade de São Paulo e em uma Unidade de Saúde da Família, além de um projeto de pesquisa que desenvolverá uma nova tecnologia de hipóxia de baixo custo (AU)