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.

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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.

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BACKGROUND: Environment with low oxygen availability can have detrimental effects on cognitive abilities. Nevertheless, exercise can have beneficial effects on cognitive abilities, and these effects may vary with the environment. Therefore, it is important for the performance of individuals to understand the uncertainties about the conditions that can compromise cognitive function. AIM: To identify which hypoxic conditions can cause attention disturbance. METHOD: A total of fourteen volunteers (24.4 ± 3.9 years old; 82.8 ± 14.9 kg weight; 178.6 ± 7.9 cm height) participated in this single-blind, randomized, with a within-subjects design study. Participants completed an adapted version of the Stroop Color-Word Test (SCWT) before and after exposure in normoxia and hypoxia (FIO 2 = 0.209 and 0.138, respectively), in two conditions: (i) at rest for 30 minutes and (ii) under exhaustive effort. The data were analyzed using a Bayesian statistical approach. RESULTS: SCWT performance under hypoxic conditions showed no difference compared with exposure moments (before and after), as well as showed no difference compared with normoxic conditions. The SpO 2 in hypoxic conditions was significantly lower than in normoxia conditions, unlike HR, which revealed no difference. The hypoxia dose at rest and under exhaustive effort was 2.5 and 0.8 %.h, respectively. CONCLUSION: Despite a drop in SpO 2 and with hypoxia doses equivalent to 2.5 and 0.8 %.h, it was not possible to confirm differences in the indices related to attention. This indicates the existence of a minimum hypoxia dose to affect cognitive performance.