Causal effect of intra-abdominal pressure on maximal voluntary isometric hip extension torque
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Intra-abdominal pressure (IAP) has been recently shown to be associated specifically with maximal voluntary isometric contraction (MVC) torque of hip extension, although the causal relationship remains unclear. The present study aimed to elucidate whether IAP has a causal effect on hip extension MVC torque.
IAP during hip extension MVC was changed by controlling the lung volume (i.e., depth of inspiration). Twelve healthy males conducted MVCs of hip extension during breath-hold at full inspiration (inspiratory condition) or expiration (expiratory condition), or during normal breath-hold (normal condition). IAP during MVCs was measured a pressure transducer placed in the rectum.
The IAP during hip extension MVC was significantly higher in inspiratory condition (132.0 ± 46.1 mmHg) than in the other two conditions and also higher in normal condition (104.6 ± 35.9 mmHg) than in expiratory condition (77.0 ± 39.1 mmHg). The hip extension MVC torque was significantly higher in inspiratory condition (297.7 ± 82.7 N m) than in expiratory condition (266.4 ± 84.5 N m). In each condition, the hip extension MVC torque correlated with IAP during the MVC task.
The current results suggest that IAP has a positive causal effect on hip extension MVC torque and that a sufficient increase in IAP directly leads to an enhancement of hip extension MVC torque.
KeywordsLung volume Core stability Abdominal muscle Diaphragm Electromyogram
Analysis of variance
Average amplitude of electromyogram
Coefficient of variation
Maximal voluntary isometric contraction
The authors do not have any financial and personal relationship with other people or organizations that could inappropriately bias this work. The authors would like to thank all the participants in this study.
Compliance with Ethical Standards
Conflict of interest
The authors declare that they have no conflict of interest.