Effects of Water-Cutting on Neuromuscular Performance

Title of Article: Effects of Water Cutting on Neuromuscular Performance

Journal: Journal of the International Society of Sports Nutrition (2016)

Link to Article

Key Findings:

1. In order to reach a lower weight class, athletes commonly utilize water manipulation techniques in the days leading to a competition weigh-in.

2. The most recurrent methods of weight-cutting include fluid restriction, sweating via saunas, and the use of diuretics.

3. In the time between weigh-in and the event, most athletes are not able to fully reverse the hypohydration.

4. Data suggests that even partial rehydration recovers neuromuscular performance.

5. The benefit of competing in a lower weight category can compensate for a decline in performance.

Background

In combat sports and powerlifting, competitors are divided into classes based on gender and body weight. The purpose of weight-class divisions is to match competitors in size and muscle mass for a level playing field and to reduce injuries. Weigh-ins are typically done 6 to 24 hours before the competition. In an attempt to gain a competitive edge, athletes commonly undergo a weight-cut in order to qualify for a lower weight category. A few days before weigh-in, many athletes also employ aggressive water-cutting techniques to further lower their body weight. In the time between weigh-in and competition, athletes then quickly regain weight and rehydrate as much as possible.

Impact of Weight Loss on Performance

There are several weight-loss methods used, often in combination, including gradual calorie restriction, increased energy expenditure through cardio, and the use of diet pills, laxatives, and diuretics. In regards to water-manipulation practices, athletes may restrict water intake and induce water loss by spitting and extended sauna use. Water-cutting is often used in the last few days before an official weigh-in because in a short period of time, loss of body fluid can result in a rapid loss in body weight. Research has suggested that a 3% loss in body mass is safe and does not decrease performance. Larger losses in body mass (>3%) has been shown to impair performance. This may be attributed to electrolyte derangements that occur in acute dehydration which can impair neuromuscular function.

Conclusion

This study aimed to evaluate if hypohydration affects neuromuscular performance, measured through muscle strength, power output, and contraction velocity. Based on urine osmolality as a marker of hydration, results revealed that 84% of participants were hypohydrated at weigh-in, showing the prevalence of water-cutting practices. Before the competition, participants were partially rehydrated but did not attain euhydration. The study found that severe dehydration, defined by a urine osmolality >1080 mOsm kg/H2O, decreased bench press muscle contraction velocity and jumping power. However, even partial rehydration resulted in increased contraction velocity and countermovement jump power at statistically significant levels. Notably, 63% of participants competed at a body weight above their weigh-in category and 69% won medals, signifying satisfactory performance in the setting of hypohydration. The data suggests that the advantage of competing in a lower weight class compensates for sub-optimal hydration.