Repeat Effort Performance is Reduced 24 h following Acute Dehydration in Mixed Martial Arts AthletesBarley, Oliver, R.1,*; Iredale, Fiona1; Chapman, Dale, W.1,2; Hopper, Amanda1; Abbiss, Chris1The Journal of Strength & Conditioning Research: September 11, 2017 - Volume Publish Ahead of Print - Issue - p doi: 10.1519/JSC.0000000000002249 Original Research: PDF Only Abstract Author Information This study sought to determine the influence of acute dehydration on physical performance and physiology in Mixed Martial Arts (MMA). MMA athletes (n=14; age: 23±4 years), completed in a randomised counterbalanced order a dehydration protocol, (DHY: 3 h cycling at 60 W in 40°C to induce 5% dehydration) or thermoneutral control (25°C: CONT) exercise, followed by ad libitum fluid/food intake. Performance testing (a repeat sled push test, medicine ball chest throw and vertical jump) was completed 3 and 24 h following the intervention, while urine and blood samples were collected before, 20 min, 3 and 24 h following the intervention. Body mass was reduced (4.8±0.8%) following DHY (p<0.001) and remained lower than CONT at 3 and 24 h post (p=0.003 and p=0.024, respectively). Compared to CONT average sled push times were slower 3 and 24 h following DHY (19±15%; p=0.001; g=1.229 and 14±15%; p=0.012; g=0.671, respectively). When compared to the CONT hand grip was weaker 3 h following DHY (53±8 and 51±8 kg; p=0.044, g=0.243 respectively) and medicine ball chest throw distances were shorter 24 h following DHY (474±52 and 449±44 cm; p=0.016, g=0.253 respectively). No significant differences were observed in vertical jump (p=0.467). Urine specific gravity was higher than CONT 20 min (p=0.035) and 24 h (p=0.035) following DHY. Acute dehydration of 4.8% body mass results in reduced physical performance 3 and 24 h following. There is need for caution when athletes use dehydration for weight loss 24 h prior to competition. 1Centre for Exercise and Sports Science Research, School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA, Australia 2Australian Institute of Sport, Bruce, Australian Capital Territory Corresponding author: Oliver Barley Centre for Exercise and Sports Science Research School of Medical and Health Sciences Edith Cowan University 270 Joondalup Drive, Joondalup WA 6027, Australia Phone: 61406670190, email@example.com Copyright © 2018 by the National Strength & Conditioning Association.