Neuromuscular performance after rapid weight loss in Olympic-style boxers

Abstract

The present study investigated the effect of a 3% rapid weight loss (RWL) procedure on neuromuscular performance in elite, Olympic-style boxers. Nine boxers were randomly assigned to two experimental procedures (RWL and control, in a randomized counter-balance order) to perform 5-s maximum isometric voluntary contractions (MVC) of the dominant leg knee extensors prior to (MVC1), and following (MVC2), a sustained, isometric contraction at 70% MVC until exhaustion. The voluntary activation (VA) was determined using percutaneous muscle stimulation and interpolated twitch technique. High (at 80 Hz) and low (at 20 Hz) frequency tetanic impulses were also delivered before and after the sustained 70% MVC to assess peripheral fatigue. Hydration status, hemodynamic parameters, and lactate concentration were assessed throughout the study. Body-mass was reduced by ∼3% (during RWL) compared to control (p = .001). As a result of the RWL protocol, MVC1 force output was 12% lower and VA deficits of 7% were observed after the fatigue protocol compared to control (p = .001). Following RWL, time to exhaustion for the sustained 70% MVC was 69 ± 20 s compared to 86 ± 34 s for control (p = .020). Peak lactate production was 53% lower in RWL compared to control (p = .001). In conclusion, the 3% RWL procedure translated into significant decline in neuromuscular performance for both brief and sustained contractions in competitive boxers.

Keywords:

• Dehydration
• combat sports
• caloric restriction
• fatigue

Acknowledgements

The authors would like to thank all athletes for their dedication and participation in this investigation. We thank the Boxing Commission of Slovenia (Boks Zveza Slovenija) and Boks Koper, especially coach Mr Milan Ðukič, for their support of this project. Thank you to Mr Marko Vidnjevič, Ms Sabina Ličen, and Ms Olivera Rakovič-Bošnjak for their technical support throughout the data collection period. We would also like to thank to Dr Adam McDonnell and Dr Vincent Martin for their thoughtful comments on the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by the Slovenian Foundation of Sport [Fundacija za šport, grant number RR-15-073, dr. Šimunič, B.].