Update October 9, 2017 – Bloody Elbow’s Iain Kidd discusses the below study here doing a good job of pointing out its strengths and shortcomings.

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It is difficult to stress the absurdity of regulators allowing rapid extreme weight cuts in mixed martial arts and other combative sports.

In short, two men or women of similar size profoundly dehydrate themselves to a smaller similar size the day before fighting . They ‘make weight’ then can rebound back to their original similar size and competition occurs. There is insufficient time to re-hydrate adequately over this period of time. This practice has led to countless injuries and and least two documented deaths in mixed martial arts.

Athletes that don’t wish to participate in rapid cuts will continue to do so unless they are comfortable facing a larger opponent.

Adding to the discussion about the consequences of rapid weight cuts, a recent study was published in the Journal of Strength and Conditioning Research noting that even 24 hours after rapid dehydration and athletes performance is impacted.

In the study, titled Repeat Effort Performance is Reduced 24 h Following Acute Dehydration in Mixed Martial Arts Athletes, the researchers had 14 MMA athletes use various rapid extreme weight cut techniques to induce 5% dehydration. After achieving the dehydrated state the athletes were allowed to re-hydrate. Following this a series of physical exercises were performed at 3 hours and 24 hours following the dehydrated state. The authors found that the athletes had reduced athletic performance even 24 hours out.

The full abstract can be found here and reads as follows –

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[degrees]C to induce 5% dehydration) or thermoneutral control (25[degrees]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.