Does intermittent hypoxia increase erythropoiesis in professional cyclists during a 3-week race?

Adequacy of an Altitude Fitness Program (Living and Training) plus Intermittent Exposure to Hypoxia for Improving Hematological Biomarkers and Sports Performance of Elite Athletes: A Single-Blind Randomized Clinical Trial

Athletes incorporate altitude training programs into their conventional training to improve their performance. The purpose of this study was to determine the effects of an 8-week altitude training program that was supplemented with intermittent hypoxic training (IHE) on the blood biomarkers, sports performance, and safety profiles of elite athletes. In a single-blind randomized clinical trial that followed the CONSORT recommendations, 24 male athletes were randomized to an IHE group (HA, n = 12) or an intermittent normoxia group (NA, n = 12). The IHE consisted of 5-min cycles of hypoxia−normoxia with an FIO2 of between 10−13% for 90 min every day for 8 weeks. Hematological (red blood cells, hemoglobin, hematocrit, hematocrit, reticulated hemoglobin, reticulocytes, and erythropoietin), immunological (leukocytes, monocytes, and lymphocytes), and renal (urea, creatinine, glomerular filtrate, and total protein) biomarkers were assessed at the baseline (T1), day 28 (T2), and day 56 (T3). Sports performance was evaluated at T1 and T3 by measuring quadriceps strength and using three-time trials over the distances of 60, 400, and 1000 m on an athletics track. Statistically significant increases (p < 0.05) in erythropoietin, reticulocytes, hemoglobin, and reticulocyte hemoglobin were observed in the HA group at T3 with respect to T1 and the NA group. In addition, statistically significant improvements (p < 0.05) were achieved in all performance tests. No variations were observed in the immunological or renal biomarkers. The athletes who were living and training at 1065 m and were supplemented with IHE produced significant improvements in their hematological behavior and sports performance with optimal safety profiles.

Effects of intermittent hypoxic training performed at high hypoxia level on exercise performance in highly trained runners

This study exanimated the effects of intermittent hypoxic training (IHT) conducted at a high level of hypoxia with recovery at ambient air on aerobic/anaerobic capacities at sea level and hematological variations. According to a double-blind randomized design, fifteen highly endurance-trained runners completed a 6-weeks regimented training with 3 sessions per week consisting of intermittent runs (6x work-rest ratio of 5':5') on a treadmill at 80-85% of maximal aerobic speed ([Formula: see text]). Nine athletes (hypoxic group, HG) performed the exercise bouts at FI0₂ = 10.6-11.4% while six athletes (normoxic group, NG) exercised at ambient air. Running time to exhaustion at a velocity corresponding to 95% [Formula: see text] significantly increased for HG while no effect was found for NG. Regarding [Formula: see text], no significant effects were found in either training group. In addition, the decline of jumping performances over a 45s-continuous maximal vertical jump test (i.e. anaerobic capacity index) tended to be lower in HG compared to NG. The levels of the studied hematological variables, including erythropoietin and hematocrit, did not significantly change for either HG or NG. These results highlight that our IHT protocol may induce additional effects on aerobic performance without compromising the anaerobic capacity index in highly-trained athletes.

Decrement in Professional Cyclists' Performance After a Grand Tour

PURPOSE

To analyze professional cyclists' performance declines after, and the exercise demands during, a Grand Tour.

METHODS

Seven professional cyclists performed 2 incremental exercise tests, 1 wk before and the day after the Vuelta España. During the race the exercise demands were analyzed on the basis of heart rate (HR). Three intensity zones were established according to reference HR values corresponding to the ventilatory- (VT) and respiratory-compensation (RCT) thresholds determined during the prerace test. In addition, exercise demands for the last weeks of the Vuelta were recalculated using the reference HR determined during the postrace test for the 3rd week and averaging the change observed in the VT and RCT per stage for the 2nd week. The reference HR for the beginning of the 2nd week was estimated.

RESULTS

A significant (P-value range, .044-.000) decrement in oxygen uptake, power output, and HR at maximal exercise, VT, and RCT was found after the race. Based on the prerace test, the mean time spent daily above the RCT was 13.8 ± 10.2 min. This time decreased -1.2 min·day^-1 across the race. When the exercise intensity was corrected according to the postrace test, the time above RCT (34.1 ± 9.9 min) increased 1.0 min·day^-1.

CONCLUSION

These data indicate that completing a Grand Tour may result in a significant decrement in maximal and submaximal endurance performance capacity. This may modify reference values used to analyze exercise demands. As a consequence, the high-intensity exercise performed by cyclists may be underestimated.

Intermittent hypoxia mobilizes hematopoietic progenitors and augments cellular and humoral elements of innate immunity in adult men

This study tested the hypothesis that intermittent hypoxia treatment (IHT) modulates circulating hematopoietic stem and progenitor cells (HSPC) and augments humoral and cellular components of innate immunity in young, healthy men. Ten subjects (group 1: age 31±4 yr) were studied before and at 1 and 7 days after a 14-day IHT program consisting of four 5-min bouts/day of breathing 10% O2, lowering arterial O2 saturation to 84% to 85%, with intervening 5-min room-air exposures. Five more subjects (group 2: age 29±5 yr) were studied during 1 IHT session. Immunofluorescence detected HSPCs as CD45+CD34+ cells in peripheral blood. Phagocytic and bactericidal activities of neutrophils, circulating immunoglobulins (IgM, IgG, IgA), immune complexes, complement, and cytokines (erythropoietin, TNF-α, IL-4, IFN-γ) were measured. In group 1, the HSPC count fell 27% below pre-IHT baseline 1 week after completing IHT, without altering erythrocyte and reticulocyte counts. The IHT program also activated complement, increased circulating platelets, augmented phagocytic and bactericidal activities of neutrophils, sharply lowered circulating TNF-α and IL-4 by >90% and ∼75%, respectively, and increased IFN-γ, particularly 1 week after IHT. During acute IHT (group 2), HSPC increased by 51% after the second hypoxia bout and by 19% after the fourth bout, and total leukocyte, neutrophil, monocyte, and lymphocyte counts also increased; but these effects subsided by 30 min post-IHT. Collectively, these results demonstrate that IHT enhances innate immunity by mobilizing HSPC, activating neutrophils, and increasing circulating complement and immunoglobulins. These findings support the potential for eventual application of IHT for immunotherapy.

Effects of intermittent hypoxic training on cycling performance in well-trained athletes

This study aimed to investigate the effects of a short-term period of intermittent hypoxic training (IHT) on cycling performance in athletes. Nineteen participants were randomly assigned to two groups: normoxic (NT, n = 9) and intermittent hypoxic training group (IHT, n = 10). A 3-week training program (5 x 1 h-1 h 30 min per week) was completed. Training sessions were performed in normoxia (approximately 30 m) or hypoxia (simulated altitude of 3,000 m) for NT and IHT group, respectively. Each subject performed before (W0) and after (W4) the training program, three cycling tests including an incremental test to exhaustion in normoxia and hypoxia for determination of maximal aerobic power (VO2max) and peak power output (PPO) as well as a 10-min cycle time trial in normoxia (TT) to measure the average power output (P(aver)). No significant difference in VO2max was observed between the two training groups before or after the training period. When measured in normoxia, the PPO significantly increased (P < 0.05) by 7.2 and 6.6% in NT and IHT groups, respectively. However, only the IHT group significantly improved (11.3%; P < 0.05) PPO when measured in hypoxia. The NT group improved (P < 0.05) P(aver) in TT by 8.1%, whereas IHT group did not show any significant difference. Intermittent training performed in hypoxia was less efficient for improving endurance performance at sea level than similar training performed in normoxia. However, IHT has the potential to assist athletes in preparation for competition at altitude.