Sewan Kim1, Eric P Homestead2, William C Byrnes2. 1. Department of Integrative Physiology, University of Colorado Boulder, 1725 Pleasant St., 354 UCB, Boulder, CO, 80309, USA. sewan.kim@colorado.edu. 2. Department of Integrative Physiology, University of Colorado Boulder, 1725 Pleasant St., 354 UCB, Boulder, CO, 80309, USA.
Abstract
PURPOSE: To determine the impact of breathing valve resistance on peak aerobic capacity ([Formula: see text]) and running economy (RE) in endurance-trained and recreationally active individuals. METHODS: Ten endurance-trained males (ETM), 10 endurance-trained females (ETF), 10 recreationally active males (RAM), and 10 recreationally active females (RAF) participated in this study. On two separate occasions, subjects performed identical graded exercise treadmill protocols using either a Hans Rudolph 2700 (high resistance) or a Daniels' (low resistance) two-way non-rebreathing valve. Parameters obtained from these protocols included energy expenditure (EE), ventilation ([Formula: see text]), heart rate, respiratory exchange ratio, RE, [Formula: see text], and time to exhaustion (TTE). RESULTS: When using the Daniels' valve, all groups had lower submaximal EE (- 2.4, - 3.4, - 2.7, and - 2.0% for ETM, ETF, RAM, and RAF) and better RE (- 2.7, - 3.5, - 1.9, and - 1.8% for ETM, ETF, RAM and RAF) across all submaximal speeds. Only the ET groups had lower submaximal [Formula: see text] (4.6 and 3.8% for ETM and ETF) when using the Daniels' valve. TTE increased when using the Daniels' valve for all groups (6.0, 10.9, 6.2 and 9.8% for ETM, ETF, RAM and RAF), but [Formula: see text] was unaltered. CONCLUSION: Compared to the Daniels' valve, the Hans Rudolph 2700 valve altered the assessment of RE, submaximal EE, and TTE regardless of fitness level or sex, but did not change [Formula: see text]. Therefore, airflow resistance of a breathing valve must be considered when assessing and comparing EE, RE and TTE in the applied and research settings.
PURPOSE: To determine the impact of breathing valve resistance on peak aerobic capacity ([Formula: see text]) and running economy (RE) in endurance-trained and recreationally active individuals. METHODS: Ten endurance-trained males (ETM), 10 endurance-trained females (ETF), 10 recreationally active males (RAM), and 10 recreationally active females (RAF) participated in this study. On two separate occasions, subjects performed identical graded exercise treadmill protocols using either a Hans Rudolph 2700 (high resistance) or a Daniels' (low resistance) two-way non-rebreathing valve. Parameters obtained from these protocols included energy expenditure (EE), ventilation ([Formula: see text]), heart rate, respiratory exchange ratio, RE, [Formula: see text], and time to exhaustion (TTE). RESULTS: When using the Daniels' valve, all groups had lower submaximal EE (- 2.4, - 3.4, - 2.7, and - 2.0% for ETM, ETF, RAM, and RAF) and better RE (- 2.7, - 3.5, - 1.9, and - 1.8% for ETM, ETF, RAM and RAF) across all submaximal speeds. Only the ET groups had lower submaximal [Formula: see text] (4.6 and 3.8% for ETM and ETF) when using the Daniels' valve. TTE increased when using the Daniels' valve for all groups (6.0, 10.9, 6.2 and 9.8% for ETM, ETF, RAM and RAF), but [Formula: see text] was unaltered. CONCLUSION: Compared to the Daniels' valve, the Hans Rudolph 2700 valve altered the assessment of RE, submaximal EE, and TTE regardless of fitness level or sex, but did not change [Formula: see text]. Therefore, airflow resistance of a breathing valve must be considered when assessing and comparing EE, RE and TTE in the applied and research settings.
Entities:
Keywords:
Energy expenditure; Running economy; Time to exhaustion