Respiratory Muscle Strength and Jiu-Jitsu-Specific Performance in Male Brazilian Jiu-Jitsu Athletes

Brazilian Jiu-Jitsu (BJJ) is an intermittent combat sport that requires repeated high-intensity efforts and sustained gripping. This analytical cross-sectional study will examine whether respiratory muscle strength is associated with BJJ-specific anaerobic performance and static kimono grip endurance in adult male BJJ athletes. Forty athletes will attend three assessment visits separated by 48 to 72 hours. Maximal inspiratory pressure, maximal expiratory pressure, and spirometric indices (forced vital capacity \[FVC\], forced expiratory volume in 1 second \[FEV1\], FEV1/FVC ratio, and peak expiratory flow \[PEF\]) will be measured at the first visit. The Jiu-Jitsu Anaerobic Performance Test and the Maximum Static Kimono Grip Test will be completed at the other two visits in randomized order. The primary analysis will examine the association between maximal inspiratory pressure and the total number of valid repetitions completed during the Jiu-Jitsu Anaerobic Performance Test. Spirometric indices will be evaluated as secondary outcomes.

Inclusion Criteria: * Male sex * Age 18 to 40 years * At least 1 year of Brazilian Jiu-Jitsu experience * Brazilian Jiu-Jitsu training on at least 2 days per week during the previous 3 months * Familiarity with gi/kimono training and the butterfly-guard lifting movement * Ability to safely and technically perform the Maximum Static Kimono Grip Test and the Jiu-Jitsu Anaerobic Performance Test * Provision of written informed consent Exclusion Criteria: * Diagnosed cardiovascular, respiratory, neurological, metabolic, or musculoskeletal condition that may affect maximal testing or participant safety * Active pain, acute injury, or relevant surgery during the previous 6 months * Current regular use of cigarettes, electronic cigarettes, or inhaled nicotine products * Medical advice to avoid maximal physical effort * Regular use of medication that may materially affect study measurements