The WATER study: Which AquaTic ExeRcises increase muscle activity and limit pain for people with low back pain?

Aquatic exercise therapy is used for the treatment and management of chronic low back pain (CLBP). However, to the authors’ knowledge, no studies to date have compared muscle activity between different aquatic exercises performed by people with CLBP. As such, this study assessed and compared muscle activity, pain, perceived exertion and exercise intensity between different rehabilitative aquatic exercises. Cross-sectional. A 25-m indoor swimming pool within a university building. Twenty participants with non-specific CLBP. Twenty-six aquatic exercises in shallow water (1.25-m depth). Muscle activity was quantified bilaterally for the erector spinae, multifidus, gluteus maximus and medius, rectus abdominis, and external and internal obliques. Mean and peak muscle activity, pain (visual analogue scale), perceived exertion (Borg scale) and exercise intensity (heart rate). Hip abduction/adduction and extension/flexion exercises produced higher activity for gluteal muscles. Variations of squat exercises increased the activity of back extensors. Higher abdominal muscle activity was produced with exercises that made use of buoyancy equipment and included leg and trunk movements while floating on the back, and with some proprioceptive and dynamic lower limb exercises. Pain occurrence and intensity were very low, with 17 exercises being pain free. This study provides evidence on trunk and gluteal muscle activity, pain, intensity and perceived exertion for people with CLBP performing aquatic exercises. The findings may be useful when prescribing exercises for rehabilitation, as physiotherapists seek to implement progression in effort and muscle activity, variation in exercise type, and may wish to target or avoid particular muscles. •This is the first study to compare trunk or gluteal muscle activity between 26 different aquatic rehabilitative exercises performed by people with CLBP.•Pain occurrence and intensity of aquatic exercises are very low, with most exercises being completely pain free.•The following aquatic exercises are particularly effective in increasing muscle activity: (a) hip abduction/adduction and extension/flexion exercises for gluteus maximus and medius; (b) squat exercises for back extensors (erector spinae and multifidus); and (c) exercises that make use of support buoyancy equipment and include leg movements while floating on the back for abdominals (rectus abdominis, and external and internal obliques).