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Caffeine Ingestion Attenuates Fatigue-induced Loss of Muscle Torque Complexity

Pethick, Jamie, Winter, Samantha L., Burnley, Mark (2017) Caffeine Ingestion Attenuates Fatigue-induced Loss of Muscle Torque Complexity. Medicine & Science in Sports & Exercise, 50 (2). pp. 236-245. ISSN 0195-9131. E-ISSN 1530-0315. (doi:10.1249/MSS.0000000000001441) (KAR id:63920)


Purpose: We tested the hypothesis that caffeine administration would attenuate the fatigue-induced loss of torque complexity. Methods: Eleven healthy participants performed intermittent isometric contractions of the knee extensors to task failure at a target torque of 50% maximal voluntary contraction (MVC), with a 60% duty factor (6 s contraction, 4 s rest), 60 min after ingesting 6 mg·kg?1 caffeine or a placebo. Torque and surface EMG signals were sampled continuously. Complexity and fractal scaling of torque were quantified using approximate entropy (ApEn) and the detrended fluctuation analysis (DFA) ? scaling exponent. Global, central and peripheral fatigue were quantified using MVCs with femoral nerve stimulation. Results: Caffeine ingestion increased endurance by 30 ± 16% (mean ± SD, P = 0.019). Complexity decreased in both trials (decreased ApEn, increased DFA ?; both P < 0.01), as global, central and peripheral fatigue developed (all P < 0.01). Complexity decreased significantly more slowly following caffeine ingestion (ApEn, -0.04 ± 0.02 vs. –0.06 ± 0.01, P = 0.004; DFA ?, 0.03 ± 0.02 vs. 0.04 ± 0.03, P = 0.024), as did the rates of global (-18.2 ± 14.1 vs. –23.0 ± 17.4 N.m.min?1, P = 0.004) and central (-3.5 ± 3.4 vs. –5.7 ± 3.9 %·min?1, P = 0.02) but not peripheral (-6.1 ± 4.1 vs. –7.9 ± 6.3 N.m.min?1, P = 0.06) fatigue. Conclusion: Caffeine ingestion slowed the fatigue-induced loss of torque complexity and increased the time to task failure during intermittent isometric contractions, most likely through central mechanisms.

Item Type: Article
DOI/Identification number: 10.1249/MSS.0000000000001441
Uncontrolled keywords: knee extension; exercise; non-linear dynamics; electromyography
Subjects: G Geography. Anthropology. Recreation > GV Recreation. Leisure > Sports sciences
Divisions: Divisions > Division of Natural Sciences > Sport and Exercise Sciences
Depositing User: Mark Burnley
Date Deposited: 09 Oct 2017 14:50 UTC
Last Modified: 09 Dec 2022 07:49 UTC
Resource URI: (The current URI for this page, for reference purposes)

University of Kent Author Information

Pethick, Jamie.

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Winter, Samantha L..

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Burnley, Mark.

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