Effect Of F1O2 On Hb/Mb-reoxygenation Rate In Human Skeletal Muscle Following Submaximal Exercise

Abstract

Previous studies have shown that Phosphocreatine (PCr) recovery is significantly altered by F1O2 even after submaximal exercise. Furthermore, recent studies have reported a high correlation between PCr recovery and Hb/Mb-O2 recovery kinetics. PURPOSE This study examined to see whether reoxygenation rate after submaximal exercise is altered by F1O2. METHODS Twenty well trained male cyclists and triathletes (31±6 yr, 180±6 cm, 76.0±9.3 kg, 9.8±4.4 BF%, VO2max = 4.81±0.60 L·min−1/63.5±5.9 ml·kg−1·min−1) who were residents of moderate altitude (1800–1900 m) participated in the study. Testing was conducted at 1860 m (PB 610–612 Torr, P1O2 ∼128 Torr). Each subject performed two randomized, single-blinded bouts of 10-minute sub-threshold steady state exercise (at 60%max) while breathing two different F1O2 concentrations (0.21 and 0.60). Immediately after exercise, 5 minutes of passive recovery took place with the exercised leg positioned horizontally. A portable near infrared continuous wave spectroscopy was used to measure changes in Hb/Mb-reoxygenation (reoxy) of the vastus lateralis using 730, 805, and 850nm wavelength. Reoxygenation rate (% • sec−1) was calculated by taking the initial 10-sec recovery slope and dividing it by the maximal deoxygenation obtained during cuff ischemia. A single-factor (F1O2) univariate repeated measures ANOVA was used to evaluate mean differences between the F1O2 0.21 and 0.60 trials. RESULTS Average power output (W) was higher in hyperoxic condition (F1O2 0.60) than in control condition (F1O2 0.21) (237±30 vs. 214±25, P< 0.01). Reoxgenation rate during initial recovery was also significantly higher (P< 0.001) in F1O2 0.60 (3.53±0.3% • sec−1) than in F1O2 0.21 (3.14±0.3% • sec−1). Compared with the control trial (F1O2 0.21) (91.1±2.2%), SpO2 was significantly higher (P< 0.01) in F1O2 0.60 (98.9±1.8%). VO2 and bLa, but not HR or RPE, were also significantly different (P< 0.01) between the two conditions. CONCLUSIONS Higher F1O2 may lead to enhanced O2 gradients between the capillary and the muscle tissue resulting in greater diffusion of O2. The results of this study suggest that, even after submaximal exercise, reoxygenation of Hb and Mb may be highly influenced by O2 availability. Supported by the United States Olympic Committee and NIH HL44125