Sex-Differences In Bench Press Muscle Activation With Pre-Exhaustion Of Triceps Brachii

• Purpose: Pre-exhaustion is a resistance training method which activates a stronger single-joint muscle to momentary exhaustion directly before a multi-joint exercise including the pre-exhausted muscle. This results in greater recruitment of muscles in the multi-joint exercise to further increase muscle strength. The pre-exhaustion method in bench press has mainly been studied in men and it is uncertain if sex-differences exists. Men are stronger than women in absolute strength, especially in the upper body but if this holds true for upper body relative strength is debated. The purpose was to investigate muscle activity by surface electromyography (EMG) between women and men in bench press with and without pre-exhaustion of triceps brachii (TB) and to compare relative strength in 10RM bench press between the sexes.Methods: 15 women and 15 men in their 20s with weight lifting experience were recruited to the study. During the first session body composition and 10 repetition maximum (10RM) bench press were determined Participants performed both protocol A and B in a cross-over design on separate days. Protocol A began with 10 RM bench press, five minutes recovery, pre-exhaustion exercise (triceps extensions to failure) immediately followed by a second round of bench press with the same 10RM load as before pre-exhaustion. Protocol B started with triceps extensions to failure immediately before bench press at their before established 10RM, five minutes of recovery then they performed 10RM bench press again. IN both protocols, EMG electrodes were attached to TB), pectoralis major (PM) and deltoideus anterior (DA). EMG values were normalized to maximum voluntary isometric contraction (MVIC) and expressed as % MVIC.Results: Bench press only EMG activity in %MVIC was similar between women and men, but analysis of variance (TB interaction p=0.02) showed that women had higher %MVIC in TB after pre-exhaustion whereas muscle activity decreased in men compared to bench press without pre-exhaustion. Yet, the number of repetitions completed in bench press after pre-exhaustion of TB were the same (women 4.3 ± 2.6 vs men 3.8 ± 2.2; p=0.55). As expected, in 10RM weight men (64.0 ± 7.1 kg) were stronger than women (37.1 ± 6.5 kg; p<0.01), however when related to fat free mass no difference was evident in relative strength between women and men.Conclusion: Men and women have similar muscle activation patterns during a 10RM bench press, but TB pre-exhaustion followed by a bench press appears to have a greater effect on TB activation in women compared to men. Absolute strength was greater in men, but normalized to fat free mass women and men had similar upper body relative strength.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Fysiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Physiology (hsv//eng)

Nyckelord

exercise physiology

wellness

health

electromyography

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