AUTHOR=Garnacho-Castaño Manuel V. , Albesa-Albiol Lluis , Serra-Payá Noemí , Gomis Bataller Manuel , Felíu-Ruano Raquel , Guirao Cano Lluis , Pleguezuelos Cobo Eulogio , Maté-Muñoz José Luis 

TITLE=The Slow Component of Oxygen Uptake and Efficiency in Resistance Exercises: A Comparison With Endurance Exercises

JOURNAL=Frontiers in Physiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2019.00357

DOI=10.3389/fphys.2019.00357

ISSN=1664-042X

ABSTRACT=<sec><title>Introduction</title><p>There is a lack of information regarding the slow component of oxygen uptake (VO<sub>2</sub>sc) and efficiency/economy in resistance exercises despite the crucial role played in endurance performance.</p></sec><sec><title>Purpose</title><p>this study aimed to compare the VO<sub>2</sub>sc, efficiency/economy, metabolic, cardiorespiratory responses, rating of perceived effort and mechanical fatigue between cycling and half-squat (HS) exercises during a constant-load test at lactate threshold (LT<sub>1</sub>) intensity.</p></sec><sec><title>Methods</title><p>Twenty-one healthy men were randomly assigned in a crossover design to perform cycle-ergometer or HS tests. The order of the two cycle ergometer tests was an incremental test for determining load-intensity in watts (W) at LT<sub>1</sub>, followed by a constant-load test at the LT<sub>1</sub> intensity. For the three HS tests, the order was a 1RM test to determine the load (kg) corresponding to the 1RM percentages to be used during the second test, incremental HS exercise to establish the load (kg) at the LT<sub>1</sub> intensity, and finally, a constant-load HS test at the LT<sub>1</sub> intensity. A rest period of 48 h between each test was established. During the HS and cycle-ergometer constant-load tests, cardiorespiratory and metabolic responses were recorded. Lower limbs fatigue was determined by a jump test before and after the constant-load tests.</p></sec><sec><title>Results</title><p>A significant exercise mode × time interaction effect was detected in VO<sub>2</sub>, heart rate, energy expenditure (EE), gross efficiency (GE), and economy (<italic>p</italic> &lt; 0.05). A significant and sustained VO<sub>2</sub> raise was confirmed in HS exercise (<italic>p</italic> &lt; 0.05) and a steady-state VO<sub>2</sub> was revealed in cycle-ergometer. A higher GE and economy were obtained in HS test than in cycle-ergometer exercise (<italic>p</italic> &lt; 0.001). In both exercises, a non-significant decrease was observed in GE and economy (<italic>p</italic> &gt; 0.05). Lower limbs fatigue was only detected after constant-load HS test.</p></sec><sec><title>Conclusion</title><p>Although the VO<sub>2</sub>, heart rate and EE responses were higher in cycling exercise, the constant-load HS test induced a greater VO<sub>2</sub>sc and EE raise than the cycling test in a predominantly aerobic metabolism. These results could explain a decrease observed in jump performance only after HS test. GE and economy could benefit from the eccentric phase of the HS exercise.</p></sec>