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Influence of neural adjustments and muscle oxygenation on task failure during sustained isometric contractions with elbow flexor muscles.
Exp Physiol. 2012 Aug; 97(8):918-29.EP

Abstract

This study investigated the adjustments in muscle activation and oxygenation in biceps and triceps brachii during two tasks sustained to failure at 20 and 60% of the maximal voluntary contraction (MVC) force. The tasks required participants either to push against a rigid restraint (force task) or to support an inertial load (position task) with the elbow flexor muscles. The surface EMG was recorded for biceps brachii, brachioradialis, triceps brachii and trapezius superior muscles. Muscle oxygenation of biceps and triceps brachii was measured by near-infrared spectroscopy. The position task was briefer (404 ± 159 s) than the force task (533 ± 194 s) when performed at 20% MVC (P = 0.011), but endurance time did not differ at 60% MVC (54 ± 19 versus 64 ± 16 s, respectively; P = 0.13). Biceps brachii oxygenation decreased slightly (by ~7%) during tasks performed at 20% MVC, whereas it dropped (-40%) for tasks sustained at 60% MVC. However, the decrease in muscle oxygenation was not a significant predictor of time to failure at the two target forces, although its contribution to muscle fatigue cannot be completely ruled out at 60% MVC. In contrast, time to failure was predicted by the increase in EMG of biceps brachii for both tasks at 20% MVC, and EMG of brachioradialis and trapezius for both tasks at 60% MVC. These results suggest that neural adjustments rather than muscle oxygenation limited the time to failure for the force and position tasks at low and high target forces.

Authors+Show Affiliations

Laboratory of Applied Biology, Université Libre de Bruxelles, 808 route de Lennik, 1070 Brussels, Belgium.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

22496501

Citation

Booghs, Cédric, et al. "Influence of Neural Adjustments and Muscle Oxygenation On Task Failure During Sustained Isometric Contractions With Elbow Flexor Muscles." Experimental Physiology, vol. 97, no. 8, 2012, pp. 918-29.
Booghs C, Baudry S, Enoka R, et al. Influence of neural adjustments and muscle oxygenation on task failure during sustained isometric contractions with elbow flexor muscles. Exp Physiol. 2012;97(8):918-29.
Booghs, C., Baudry, S., Enoka, R., & Duchateau, J. (2012). Influence of neural adjustments and muscle oxygenation on task failure during sustained isometric contractions with elbow flexor muscles. Experimental Physiology, 97(8), 918-29. https://doi.org/10.1113/expphysiol.2011.064303
Booghs C, et al. Influence of Neural Adjustments and Muscle Oxygenation On Task Failure During Sustained Isometric Contractions With Elbow Flexor Muscles. Exp Physiol. 2012;97(8):918-29. PubMed PMID: 22496501.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Influence of neural adjustments and muscle oxygenation on task failure during sustained isometric contractions with elbow flexor muscles. AU - Booghs,Cédric, AU - Baudry,Stéphane, AU - Enoka,Roger, AU - Duchateau,Jacques, Y1 - 2012/04/11/ PY - 2012/4/13/entrez PY - 2012/4/13/pubmed PY - 2012/12/18/medline SP - 918 EP - 29 JF - Experimental physiology JO - Exp Physiol VL - 97 IS - 8 N2 - This study investigated the adjustments in muscle activation and oxygenation in biceps and triceps brachii during two tasks sustained to failure at 20 and 60% of the maximal voluntary contraction (MVC) force. The tasks required participants either to push against a rigid restraint (force task) or to support an inertial load (position task) with the elbow flexor muscles. The surface EMG was recorded for biceps brachii, brachioradialis, triceps brachii and trapezius superior muscles. Muscle oxygenation of biceps and triceps brachii was measured by near-infrared spectroscopy. The position task was briefer (404 ± 159 s) than the force task (533 ± 194 s) when performed at 20% MVC (P = 0.011), but endurance time did not differ at 60% MVC (54 ± 19 versus 64 ± 16 s, respectively; P = 0.13). Biceps brachii oxygenation decreased slightly (by ~7%) during tasks performed at 20% MVC, whereas it dropped (-40%) for tasks sustained at 60% MVC. However, the decrease in muscle oxygenation was not a significant predictor of time to failure at the two target forces, although its contribution to muscle fatigue cannot be completely ruled out at 60% MVC. In contrast, time to failure was predicted by the increase in EMG of biceps brachii for both tasks at 20% MVC, and EMG of brachioradialis and trapezius for both tasks at 60% MVC. These results suggest that neural adjustments rather than muscle oxygenation limited the time to failure for the force and position tasks at low and high target forces. SN - 1469-445X UR - https://www.unboundmedicine.com/medline/citation/22496501/Influence_of_neural_adjustments_and_muscle_oxygenation_on_task_failure_during_sustained_isometric_contractions_with_elbow_flexor_muscles_ DB - PRIME DP - Unbound Medicine ER -