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Exhaustive Intermittent Cycling Preferentially Decreases Explosive Over Maximal Voluntary Torque in the Knee Extensors, With No Difference Between Normoxia and Moderate to Severe Hypoxia.

Authors :
Girard, Olivier
Racinais, Sébastien
Source :
International Journal of Sports Physiology & Performance; Nov2023, Vol. 18 Issue 11, p1352-1356, 5p
Publication Year :
2023

Abstract

Purpose: To compare the effects of graded hypoxia during exhaustive intermittent cycling on subsequent rapid and maximal torque-production capacity. Methods: Fifteen well-trained cyclists repeated intermittent cycling bouts (15 s at 30% of anaerobic power reserve; rest = 45 s) until exhaustion at sea level (FiO<subscript>2</subscript> ∼0.21/end-exercise arterial oxygen saturation ∼96%), moderate hypoxia (FiO<subscript>2</subscript> ∼0.16/∼90%), and severe hypoxia (FiO<subscript>2</subscript> ∼0.12/∼79%). Rapid (rate of torque development [RTD]) and maximal isometric torque-production capacities of the knee extensors were assessed at baseline (visit 1) and exhaustion (visits 2–4). Results: Exercise capacity decreased with hypoxia severity (39 [30], 22 [13], and 13 [6] cycle efforts in sea level, moderate hypoxia, and severe hypoxia, respectively; P =.002). Changes in maximal-voluntary-contraction torque between baseline and postexercise in all conditions were not statistically significant (pooled values: −2.6% [5.7%]; P =.162). Peak RTD measured postexercise was reduced below baseline in all conditions (–21.5% [5.1%]; P ≤.015). Compared with baseline, absolute RTD values were lower at 0- to 30-millisecond (–35.1% [5.3%], P ≤.020), 0- to 50-millisecond (–40.0% [3.9%], P ≤.002), 0- to 100-millisecond (–30.7% [3.7%], P ≤.001), and 0- to 200-millisecond (–18.1% [2.4%], P ≤.004) time intervals in all conditions. Conclusions: Exhaustive intermittent cycling induces substantial yet comparable impairments in RTD of knee extensors between normoxia and moderate to severe hypoxia. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
15550265
Volume :
18
Issue :
11
Database :
Complementary Index
Journal :
International Journal of Sports Physiology & Performance
Publication Type :
Academic Journal
Accession number :
173231076
Full Text :
https://doi.org/10.1123/ijspp.2023-0101