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Effects of Rapid Weight Loss on Physiology and Performance in Mixed Martial Arts Athletes

Athletes competing in Mixed Martial Arts (MMA) weigh in 24 h before their event starts. Rapid weight loss using dehydration is a common method used by MMA athletes to rapidly reduce body weight prior to weigh in, thereby allowing them to compete in a lower than intended weight class. Changes in electrolyte concentration, plasma volume and haematocrit associated with dehydration may negatively affect aerobic performance. However studies have provided mixed results on the effect of dehydrations on anaerobic performance. There is currently no known published data examining the amount of weight lost by MMA athletes prior to competition, nor on the effect of such rapid weight loss on their physiology and performance.

The present study aims to examine: i) the amount of weight lost by MMA athletes of different weight classes, and ii) to examine the effect of such rapid weight loss on performance (vertical jump, medicine ball throw and repeated sled push) and physiology (body composition, total haemoglobin mass, haematocrit, electrolyte concentration, urine specific gravity and urine osmolality) of MMA athletes. A total of 14 MMA athletes between the ages of 18 to 40 y with at least 2 y of competitive experience will be recruited. Participants will perform a familiarisation session, followed by two experimental sessions euhydrated and hypohydrated in a randomised order. During the hypohydrated trial athletes will lose 4% of their bodyweight (BW) over 3 h in a heated chamber wearing a sweat suit, they will then undergo a 3 h recovery period to consume fluids/food, followed by performance testing. Then a further 21 h recovery period will be allowed before a second performance testing session. Prior to weight loss, immediately post weight loss, pre performance testing and 21 h post weight loss a urine sample and blood sample will be obtained. At the same time points blood pressure, heart rate and body weight will be assessed. Total haemoglobin mass will be measured immediately post weight loss and after the 21 h recovery. Body composition will be assessed before both performance tests.

Rapid weight loss is a common practice in combat sports and it is essential that accurate data is collected to aid in the development of best practice guidelines.

Project duration



Mr Oliver Barley
Associate Professor Chris Abbiss
Mrs Fiona Iredale

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