Repeat Effort Performance Is Reduced 24 Hours After Acute Dehydration in Mixed Martial Arts Athletes

Abstract

Barley, OR, Iredale, F, Chapman, DW, Hopper, A, and Abbiss, C. Repeat effort performance is reduced 24 hours after acute dehydration in mixed martial arts athletes. J Strength Cond Res 32(9): 2555-2561, 2018-This study sought to determine the influence of acute dehydration on physical performance and physiology in mixed martial arts (MMA). Mixed martial arts athletes (n = 14; age: 23 ± 4 years) completed in a randomized counterbalanced order a dehydration protocol, (DHY: 3-hour 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 hours and 24 hours after the intervention, whereas urine and blood samples were collected before, 20 minutes, 3 hours, and 24 hours after the intervention. Body mass was reduced (4.8 ± 0.8%) after DHY (p < 0.001) and remained lower than CONT at 3 hours and 24 hours after DHY (p = 0.003 and p = 0.024, respectively). Compared with CONT, average sled push times were slower 3 hours and 24 hours after DHY (19 ± 15%; p = 0.001; g = 1.229 and 14 ± 15%; p = 0.012; g = 0.671, respectively). When compared with the CONT, handgrip was weaker 3 hours after DHY (53 ± 8 and 51 ± 8 kg; p = 0.044, g = 0.243, respectively) and medicine ball chest throw distances were shorter 24 hours after 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 minutes (p = 0.035) and 24 hours (p = 0.035) after DHY. Acute dehydration of 4.8% body mass results in reduced physical performance 3 and 24 hours after DHY. There is need for caution when athletes use dehydration for weight loss 24 hours before competition.

Acute Dehydration Impairs Endurance Without Modulating Neuromuscular Function

“…Ad libitum fluid and food consumption resulted in body mass, serum osmolality and haematocrit returning to baseline, however, urine osmolality and USG did not (Table 1 ). These results are similar to those reported previously in research examining acute dehydration in combat athletes ( Barley et al, 2017b ) and indicate the complexity of assessing dehydration and the limitations of using a single (or even multiple) measure of hydration status ( Armstrong, 2007 ). Nevertheless, and of significant practical importance, acute dehydration followed by a rehydration period has been found to impair exercise performance even when several markers of hydration have returned to baseline ( Barley et al, 2017b ).…”

“…The method of how dehydration is induced may also be of some importance, as it can be induced using exercise (actively) or by using environmental stress at rest (passively) ( Cheuvront and Kenefick, 2014 ). The negative effects of both active and passive dehydration have also been found to persist even following rehydration, with researchers reporting impairments in repeat-effort capacity ( Barley et al, 2017b ), sports-specific skills ( Baker et al, 2007 ), mood ( Hall and Lane, 2001 ) and cognitive function ( Choma et al, 1998 ) for up to 5 h, and in some cases 24 h, despite ad libitum rehydration. Such findings have substantial implications for athletes in sports with weight classifications (e.g., combat sports), as athletes often attempt to rapidly lose and regain body mass prior to being weighed for competition, with athletes reporting losing 3–5% of their body mass rapidly before being weighed for competition ( Barley et al, 2017a ).…”

“…However, the effects of acute dehydration on performance and neuromuscular function following a periods of recovery and/or rehydration is even less clear due to a paucity of research ( Bigard et al, 2001 ; Rodrigues et al, 2014 ). As a result, it is currently unclear whether the reduction in exercise capacity observed in the hours following dehydration ( Hall and Lane, 2001 ; Barley et al, 2017b ) results from prolonged alterations in neuromuscular function (i.e., central and peripheral fatigue) or other mechanisms such as altered carbohydrate metabolism or mental fatigue ( Sjøgaard, 1985 ; Montain et al, 1998 ; Casa, 1999 ; Bigard et al, 2001 ; Minshull and James, 2012 ). Indeed, dehydration has also been found to negatively influence mood and cognitive function ( Choma et al, 1998 ; Hall and Lane, 2001 ) and increase perceived exertion, which could be associated with increased mental fatigue ( Marcora et al, 2009 ; Barley et al, 2017b ).…”

Weight Loss Strategies in Combat Sports and Concerning Habits in Mixed Martial Arts

“…greater amount compared with BJJ (P<0.001) ( Table 3). In most 239 combat sports, it was reported that the majority of weight lost in 240 the 24 h before weigh-in was recovered prior to competition and 241 the majority of weight lost was typically regained 7 days 242 following weigh-in ( The present study sought to investigate the strategies used for tasks, 6,12,17 or at least no increase in competitive success. 24,25 We 315 also provide further evidence that weight loss practices in MMA 316 may be more extreme than other combat sports 6 with MMA 317 reporting significantly greater weight loss than other combat 318 sports within two weeks and 24 h of weighing-in (Table 3).…”

“…These findings conflict with previous research indicating that 335 even when provided with 24 h of ad libitum fluid/food intake 336 athletes may not be adequately rehydrating. 2,12 Clearly, further 337 research is needed to assess the recovery strategies and their 338 efficacy in combat sports following weigh-ins.…”