The effect of induced alkalosis and submaximal cycling on neuromuscular response during sustained isometric contraction |
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| Authors: | Angus M Hunter Giuseppe De Vito Claire Bolger Hugh Mullany Stuart D R Galloway |
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| Institution: | 1. Nutrition, Physical Activity and Health Research Group , University of Stirling , Stirling, Scotland a.m.hunter1@stir.ac.uk;3. Nutrition, Physical Activity and Health Research Group , University of Stirling , Stirling, Scotland;4. UCD Institute for Sport and Health, University College Dublin , Dublin, Ireland;5. Nutrition, Physical Activity and Health Research Group , University of Stirling , Stirling, Scotland;6. Mullany Engineering Consultancy Ltd , Dublin, Ireland |
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| Abstract: | Abstract The aim of this study was to determine if inducing metabolic alkalosis would alter neuromuscular control after 50 min of standardized submaximal cycling. Eight trained male cyclists (mean age 32 years, s = 7; Vdot]O2max 62 ml · kg?1 · min?1, s = 8) ingested capsules containing either CaCO3 (placebo) or NaHCO3 (0.3 g · kg?1 body mass) in eight doses over 2 h on two separate occasions, commencing 3 h before exercise. Participants performed three maximal isometric voluntary contractions (MVC) of the knee extensors while determining the central activation ratio by superimposing electrical stimulation both pre-ingestion and post-exercise, followed by a 50-s sustained maximal contraction in which force, EMG amplitude, and muscle fibre conduction velocity were assessed. Plasma pH, blood base excess, and plasma HCO3 were higher (P < 0.01) during the NaHCO3 trial. After cycling, muscle fibre conduction velocity was higher (P < 0.05) during the 50-s sustained maximal contraction with NaHCO3 than with placebo (5.1 m · s?1, s = 0.4 vs. 4.2 m · s?1, s = 0.4) while the EMG amplitude remained the same. Force decline rate was less (P < 0.05) during alkalosis-sustained maximal contraction and no differences were shown in central activation ratio. These data indicate that induced metabolic alkalosis can increase muscle fibre conduction velocity following prolonged submaximal cycling. |
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| Keywords: | Muscle fibre conduction velocity central activation ratio bicarbonate ingestion pH electromyography |
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