Key result
Hypoxic exercise at the same power output as normoxic exercise increased mean heart rate (154 vs 139 bpm, p<0.01) and delayed cardiac autonomic recovery.
Why the study?
Exercise physiological responses can be markedly affected by acute hypoxia, prompting investigation into cardiac autonomic and physiological responses to different hypoxic training protocols.
Does hypoxic exercise alter cardiac autonomic and physiological responses compared to normoxic exercise in men?
Does hypoxic exercise alter cardiac autonomic and physiological responses compared to normoxic exercise in men?
Absolute Event Rate: 154% vs 139%
p-value: p=<0.01
Heart rate-matched hypoxic exercise yields similar cardiac autonomic responses to normoxic exercise despite lower mechanical load, whereas power-matched hypoxic exercise increases metabolic stress and delays autonomic recovery.
May warrant HR monitoring in hypoxic training; leaves open clinical relevance for autonomic recovery.
Exercise physiological responses can be markedly affected by acute hypoxia. We investigated cardiac autonomic and physiological responses to different hypoxic training protocols. Thirteen men performed three exercise sessions (5×5-min; 1-min passive recovery): normoxic exercise at 80% of the power output (PO) at the first ventilatory threshold (N), hypoxic exercise (FiO2=14.2%) with the same PO as N (HPO) and hypoxic exercise at the same heart rate (HR) as N (HHR). PO was lower in HHR (21.1±9.3%) compared to N and HPO. Mean HR was higher in HPO (154±11 bpm, p<0.01) than N and HHR (139±10 vs. 138±9 bpm; p=0.80). SpO2 was reduced (p<0.01) to a similar extent (p>0.05) in HPO and HHR compared to N. HR recovery (HRR) and HR variability indices were similar in N and HHR (p>0.05) but reduced in HPO (p<0.05), mirroring a delayed parasympathetic reactivation. Blood lactate and ventilation were similar in N and HHR (p>0.05) and increased in HPO (p<0.001). During recovery oxygen consumption and ventilation were similar in N and HHR (p>0.05) and increased in HPO (p<0.01). Moderate HR-matched hypoxic exercise triggers similar cardiac autonomic and physiological responses to normoxic exercise with a reduced mechanical load. On the contrary, the same absolute intensity exercise in hypoxia is associated with increased exercise-induced metabolic stress and delayed cardiac autonomic recovery.
No takes yet. Share an insight, caveat, or question.
Fornasiero et al. (2019) studied this question. Hypoxic exercise vs. Normoxic exercise was evaluated on Mean heart rate (p=<0.01). Hypoxic exercise at the same power output as normoxic exercise increased mean heart rate (154 vs 139 bpm, p<0.01) and delayed cardiac autonomic recovery.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: