The relationship between test protocol and the development of exercise-induced hypoxemia (EIH) in highly trained athletes

Abstract

Healthy male endurance-trained cyclists [n = 11, age = 27.3 (3.9) years; mass = 73.0 (9.3) kg; height = 180.5 (6.9) cm; maximal oxygen consumption ($\dot VO_{2max}$ = 71.1 (5.8) ml · kg⁻¹ · min⁻¹, mean ± (SD)] were recruited to assess the relationship between test protocol and the development of desaturation of arterial hemoglobin with oxygen, during incremental exercise tests to maximal aerobic capacity$(\dot VO_{2max} )$. All subjects demonstrated resting pulmonary function within normal limits [forced vital capacity (FVC) = 6.0 (0.9); forced expiratory volume (FEV_1.0) = 4.9 (0.6); FEV_1.0/FVC = 0.8 (0.1)] and completed three ramped$\dot VO_{2max}$ tests (Mijnhardt KEM-3 electronically braked cycle ergometer) beginning at 0 W with increments of either 20, 30 or 40 W · min⁻¹. All periods of testing were separated by a minimum of 72 h.$\dot VO_{2max}$, peak minute ventilation$(\dot V_{Epeak} )$ (Medical Graphics, CPX-D), peak heart rate (ƒ_cpeak)), peak power output$(\dot W_{peak} )$, and minimum percentage arterial oxyhemoglobin saturation (%S _aO_2min) (Omeda Biox 3740 pulse oximeter) were determined. There were no significant differences (p > 0.05) in$(\dot W_{peak} )$ [191.5 (26.2), 196.0 (24.4), 194.3 (23.9) 1 · min⁻¹] ƒ_cpeak [191.4 (7.0), 190.3 (5.5), 187.8 (5.9) beats · min⁻¹],$\dot VO_{2max}$ [5.0 (0.5), 5.1 (0.4), 5.1 (0.5) 1 · min⁻¹] or %S _aO_2min [89.5 (1.5), 89.6 (1.3), 90.0 (2.3)] between protocols. The 20-W protocol [417 (27) W] demonstrated significantly lower$\dot W_{peak}$ (P < 0.05) than the 30-W [434 (36) W] and 40-W [453 (38) W] protocols, indicating that peripheral fatigue may play an important factor in response to these tests. The results of this study demonstrate that arterial desaturation occurs as a result of intense exercise in highly trained athletes independent of the rate of attainment of$\dot VO_{2max}$.