Maximal Oxygen Uptake May be Limited by Sensation of Muscle Oxygenation

ABSTRACT

Background: The aim of the present study was to investigate the effects of restricted muscular oxygenation on VO2max, peak power output (PPO), and maximum heart rate (HRmax).

Methods: Six young healthy male subjects participated in four testing sessions within a 2-week period. On four separate days, participants performed stepwise incremental exercise tests to exhaustion (VO2maxNor) on a cycle ergometer under control condition and with thigh cuffs inflated to external pressure of 60, 90 and 120 mmHg, respectively (Cuff60, Cuff90, Cuff120), following a counterbalanced order. Respiratory gas exchange responses, heart rate and near infrared spectroscopy (NIRS) measurements of muscle oxygenation from rectus femoris muscle were continuously monitored during the four tests.

Results: A decrease proportional to the degree of cuff inflation was observed in VO2max (Nor = 42.9 ± 3.7, Cuff60 = 34.5 ± 5.8, Cuff90 = 33.4 ± 3.5, Cuff120 = 31.2 ± 6.8 ml·kg-1·min-1; p<0.05). Lower values of PPO (Nor= 298 ± 64, Cuff60 = 252 ± 35, Cuff90 = 213 ± 26, Cuff120 = 210 ± 20 Watts, P<0.05) and HRmax (Nor = 183.7 ± 4.8, Cuff60 = 177.5 ± 7.7, Cuff90 = 168.8 ± 14.0, Cuff120 = 170.8 ± 17.1 beats·min-1, p<0.05) were recorded in cuff conditions. Final values of muscle deoxygenation and rate of perceived exertion were not different among the four conditions.

Conclusions: It appears that with cuff application, muscle oxygenation is compromised leading to premature sensation of maximum effort, which in turn prevents the heart and the muscle from attaining their maximum capacity.