Vascular Dynamics and Peripheral Oxygen Uptake in Obese Individuals during Progressive Physical Exercise

摘要

Background: Obese men show higher O-2 consumption than lean men during physical exercise, with a trend toward higher peripheral O-2 extraction; this is probably due to their larger muscle mass. Objectives: The aim of this study was to examine this phenomenon by measuring 2 vasoactive substances, endothelin-1 (ET-1) and nitric oxide (NO), during a progressive submaximal exercise. Methods: Seventeen obese (body mass index [BMI] 38.6) and 15 lean (BMI 22.5) men performed a maximal progressive cycle ergometer exercise to determine peak power output (PPO) and peak O-2 consumption ((V)over dotO-2peak); thereafter, they performed a submaximal cycle ergometer incremental test (every 6 min) at the same percentage of (V)over dotO-2peak until they reached 57.5% PPO. Blood samples were collected at rest and at the end of every step to measure ET-1 and NO concentrations. Results: At rest, the ET-1 and NO concentrations in obese men and lean controls were the same. However, during exercise, the ET-1 concentration at each step was significantly lower (p 0.05) in the obese group. There was no significant difference in NO concentration between the 2 groups, although the increase at the beginning of the exercise session was faster in obese individuals. During submaximal exercise, end-tidal O-2 pressure (PETO2) was lower in the obese group, with a significant difference in the PETO2/fat-free mass ratio at each step. Conclusions: ET-1 and NO levels during physical exercise are different in obese versus lean men. This may support the notion that increased O-2 consumption in obesity is due to different behaviors of the cardiorespiratory and circulatory systems. (c) 2017 S. Karger AG, Basel