Augmented supraspinal fatigue following constant-load cycling in the heat

Goodall, Stuart, Charlton, Kayleigh, Hignett, C., Prichard, Jonathan, Barwood, Martin, Howatson, Glyn and Thomas, Kevin (2015) Augmented supraspinal fatigue following constant-load cycling in the heat. Scandinavian Journal Of Medicine & Science In Sports, 25 (S1). pp. 164-172. ISSN 0905-7188

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Official URL: http://dx.doi.org/10.1111/sms.12370

Abstract

The development of central fatigue is prominent following exercise-induced hyperthermia, but the contribution of supraspinal fatigue is not well understood. Seven endurance-trained cyclists (mean ± SD peak O2 uptake, 62.0 ± 5.6 mL/kg/min) completed two high-intensity constant-load cycling trials (296 ± 34 W) to the limit of tolerance in a hot (34 °C, 20% relative humidity) and, on a separate occasion, for the same duration, a control condition (18 °C, 20% relative humidity). Core body temperature (Tc) was measured throughout. Before and immediately after each trial, twitch responses to supramaximal femoral nerve and transcranial magnetic stimulation were obtained from the knee extensors to assess neuromuscular and corticospinal function, respectively. Exercise time was 11.4 ± 2.6 min. Peak Tc was higher in the hot compared with control (38.36 ± 0.43 °C vs 37.86 ± 0.36 °C; P = 0.035). Post-exercise reductions in maximal voluntary contraction force (13 ± 9% vs 9 ± 5%), potentiated twitch force (16 ± 12% vs 21 ± 13%) and voluntary activation (9 ± 7% vs 7 ± 7%) were similar in hot and control trials, respectively. However, cortical voluntary activation declined more in the hot compared with the control (8 ± 3% vs 3 ± 2%; P = 0.001). Exercise-induced hyperthermia elicits significant central fatigue of which a large portion can be attributed to supraspinal fatigue. These data indicate that performance decrements in the heat might initially originate in the brain.

Item Type: Article
Uncontrolled Keywords: Brain; exercise; hyperthermia; performance
Subjects: C600 Sports Science
Department: Faculties > Health and Life Sciences > School of Life Sciences > Sport, Exercise and Rehabilitation
Depositing User: Paul Burns
Date Deposited: 12 May 2015 09:23
Last Modified: 03 Nov 2016 12:57
URI: http://nrl.northumbria.ac.uk/id/eprint/22440

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