Study – Rapid Weight Cuts in MMA Can Lead to Impaired Strength and Cognitive Function at Fight Time

A study was recently published in the British Journal of Sports Medicine with critical findings addressing rapid extreme weight cutting practices in mixed martial arts.

In the study, titled “The cognitive and physical effects of pre-competition rapid weight loss and gain in mixed martial arts athletes” the authors recruited 60 mixed martial artists and examined their weight loss and weight gain prior to competition.   Their weight was measure 10-14 days prior to competition, 24 hours prior to competition and 3 hours prior to competition.  The authors noted that those that made weight through profound dehydration had measurably impaired strength and cognitive function which did not rebound prior to competition time.  Specifically the authors concluded that “In athletes who experienced the most Time-2 fluid loss, the return of body mass and USG to near baseline levels at Time-3 did not fully reverse the effects on SSHR, lower body power and some cognitive functions (KDst). It was concluded that weight cutting causes a substantial disruption to physiology that may impact health and performance“.

The full abstract reads as follows:

This study examined the acute physiological and cognitive effects of pre-competition rapid weight loss and gain (weight cutting) on mixed martial arts (MMA) athletes. 60 (8 female; 52 male) licensed amateur and professional MMA athletes participated in the study. Measurements were collected at three time points prior to a competition: 10–14 days (Time-1; n=50), 24 hours (Time-2; n=40) and 1–3 hours (Time-3; n=26). Measurements included body mass (kg), King-Devick Test (KD), Sit-to-Stand Heart Rate Test (SSHR), Vertical Jump Test (VJ), grip strength (kg) and urine specific gravity (USG) (mmol). Also, relative change [((Time-1 – Time-2)/Time-1) × 100] in both body mass and USG were compared to other dependent variables. The following variables [mean(SD)] at Time-2 were different from Time-1 before returning to near baseline at Time-3: body mass [74.44 (13.11) vs 70.77 (12.26) vs 74.07 (13.33) kg; F (1,1.24)=50.72, p=0.00], left grip strength [111 (27) vs 98 (25) vs 108 (27) kg; F (1,2)=23.38, p=0.00], right grip strength [112 (25) vs 100 (23) vs 110 (24) kg; F (1,2)=17.91, p=0.00], USG [1.008 (0.003) vs 1.032 (0.004) vs 1.007 (1.003) mmol; F (1,2)=299, p=0.00] and KD sum time (KDst) adjusted for errors [41.39 (4.78) vs 42.44 (5.92) vs 38.58 (4.58) s; F (1,1.41)=8, p=0.00]. Relative change in USG was significantly correlated with relative change in body mass [rs (30)=−0.405; p=0.03]; and left leg VJ force at Time-2 [rs (18)=−0.71; p=0.00] and Time-3 [rs (11)=−0.64; p=0.04]. Relative change in body mass was significantly correlated with KDst at Time-2 [rs (30)=−0.57; p=0.00] and Time-3 [rs (21)=−0.49; p=0.00]; and SSHR maximum at Time-2 [rs (30)=0.41; p=0.03] and Time-3 [rs (21)=0.49; p=0.03]. Findings indicate that a significant amount of weight loss while weight cutting was due to fluid loss that was sufficient at Time-2 to impair upper body strength, lower body power, SSHR response and cognitive function (higher KDst and errors). In athletes who experienced the most Time-2 fluid loss, the return of body mass and USG to near baseline levels at Time-3 did not fully reverse the effects on SSHR, lower body power and some cognitive functions (KDst). It was concluded that weight cutting causes a substantial disruption to physiology that may impact health and performance.

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