Electromyographic analysis of abdominal muscle activation during side bridge variations: effects of hip angle and breathing pattern

Purpose This study investigated the influence of hip angle and breathing patterns on electromyography (EMG) of abdominal muscles during side bridge (SB) exercises. While certain studies have explored the isolated effects of hip position or breathing on abdominal EMG activity, there is limited evidence on how their interaction affects abdominal EMG activity, particularly during functional tasks such as SB. Methods Thirty healthy males performed three side bridge: SB in neutral, SB with hip flexion (SB+HF), and SB with hip extension (SB+HE), each with resting (RE) and maximal expiration (ME) breathing. Surface EMG recorded muscle activity from the rectus abdominis (RA), external oblique (EO), and transverse abdominis/internal oblique (TrA/IO) muscles. Before testing, maximum voluntary isometric contractions (MVICs) were recorded for each muscle. EMG data were normalised to %MVIC. The Friedman test was used for analysis. Results The results showed significant differences in muscle activity between exercise combinations. EO and RA activity differed notably between RE and ME conditions (p < 0.05), with ME producing higher %MVIC. The highest activity for RA and EO occurred during SB+HE/ME, averaging 24.80 ± 13.66 and 28.67 ± 12.21, respectively. For TrA/IO, significant differences (p < 0.05) were primarily between RE and ME in most comparisons, with the highest activation seen during SB+HF/RE (18.30 ± 1.69). Conclusions The hip angle and breathing pattern significantly affect abdominal muscle activity during SB exercises. For instance, practitioners might prioritise ME during exercises with a hip extension position to maximise RA and EO activity. Understanding the varying impacts of hip positioning and breathing techniques will ultimately lead to improved athletic performance and rehabilitation outcomes.