The effect of transversus abdominis activation on exercise-related transient abdominal pain

Objectives: Exercise-related transient abdominal pain (ETAP) affects 40-60% of the physically active population, is detrimental to performance but of unknown aetiology. Excessive movement of abdominal peritoneum is one proposed mechanism. Transversus abdominis (TrA) function may play a role reducing in the incidence of Exercise-related transient abdominal pain via the tensioning of the thoracolumbar fascia or increasing intra-abdominal pressure. The aim of this study is to identify any relationship between transversus abdominis function and exercise-related transient abdominal pain, hypothesing that those with stronger transversus abdominis will have lower incidence of exercise-related transient abdominal pain.

Design: Observational study design.

Methods: Trunk muscle strength was measured clinically using the functional Sahrmann test. Contraction of transversus abdominis was measured by ultrasound imaging of resting muscle size and calculating the change in thickness with a voluntary contraction. Participants completed questionnaires describing any exercise-related transient abdominal pain symptoms, and were divided into four groups dependent upon frequency of any symptoms (never, yearly, monthly and weekly). Between group differences were analysed using analysis of covariance, with Bonferroni correction adjusting for age and training of participants using STATA. Poisson regression determined incident rate ratios for relevant variables.

Results: Data was obtained from fifty runners (28 male, 25.8 ± 7.0 years). Sahrmann test score and frequency of Exercise-related transient abdominal pain were significantly different between groups (p = 0.002) with asymptomatic runners having significantly higher Sahrmann test scores (stronger muscles) than weekly and yearly Exercise-related transient abdominal pain groups (p = 0.001, p = 0.02). There were significant between group differences for resting transversus abdominis thickness (p = 0.034) but not for transversus abdominis thickness change (p = 0.555).

Conclusions: Participants who had stronger trunk muscles and larger resting Transversus abdominis size experienced Exercise-related transient abdominal pain less.