VENTILATORY CHEMOSENSIVITY OF JUNIOR ELITE CYCLISTS AT ALTITUDE

Abstract

Early acclimatization to altitude is characterized by an increase in resting ventilation facilitated by an increase in hypoxic ventilatory response (HVR), but there is little information comparing ventilatory chemosensitivity of athletes undergoing short-term altitude training with those native to altitude. PURPOSE To examine ventilatory adaptation following short-term or life-long residence at 2690m altitude in elite junior cyclists. METHODS Subjects were seven members of the Australian men's U23 cycling team (AU) and six from the State of Mexico men's U19 cycling team (MX). For AU, end-tidal CO2 pressure (PETCO2), HVR and oxyhemoglobin saturation (SpO2) were measured at sea level (SL) and after 15 d at altitude (D15). Hypercapnic ventilatory response (HCVR) was measured at SL and after 10 d at altitude (D10). For MX, all variables were measured at altitude. RESULTS At D15, PETCO2 for AU was lower (p < 0.001) than at SL. PETCO2 tended to be lower for AU than MX (32.1 ±3.3 vs 34.1 ±0.9mmHg; p = 0.18; F-ratio for variances, p < 0.01) and SpO2 was lower for AU than MX (94.0 ±1.7 vs 95.8 ±0.7%; p < 0.05). There was a significant correlation between SpO2 and PETCO2 at D15 for AU (r = −0.92, p < 0.005), but not for MX (r=0.28). HVR tended to be higher for AU than MX (0.69 ±0.49 vs 0.25 ±0.17L.min−1.%−1; p = 0.06), as was HCVR (2.03 ±0.62 vs 1.42 ±0.43L.min−1.mmHg−1; p = 0.07). For AU, the HVR at SL was correlated with SpO2 (r=0.78) and PETCO2 (p = −0.81) at D15, and HCVR at D10 was correlated with SpO2 (r=0.81) and PETCO2 (r = −0.81) at D15 (all p < 0.05). There were no significant correlations amongst HVR, HCVR and SpO2 or PETCO2 for MX. CONCLUSION For elite junior cyclists undergoing short-term altitude exposure, HVR and HCVR play a role in ventilatory acclimatization and maintenance of SpO2, but these variables are not related to PETCO2 or SpO2 in cyclists who are life-long altitude residents. This research was supported by an Australian Sports Comission grant