Muscle activity during aquatic and land exercises in people with and without low back pain

Background: Chronic low back pain (CLBP) is the most prevalent musculoskeletal disorder. Aquatic exercises are commonly used by physiotherapists for CLBP treatment and management but there are no data on trunk muscle activation during aquatic exercises in people with CLBP.
Objective: We quantified activation of trunk and gluteal muscles, exercise intensity, pain and perceived exertion in people with and without CLBP when performing water and land exercises.
Design: Cross-sectional.
Methods: Twenty participants with non-specific CLBP and 20 healthy participants performed 15 aquatic exercises and 15 similar land exercises. Mean and peak muscle activation were measured bilaterally from erector spinae, multifidus, gluteus maximus, gluteus medius, rectus abdominis, external oblique and internal oblique, using waterproof and wireless surface electromyography. Exercise intensity (heart rate), perceived exertion (Borg scale) and, for the CLBP group, pain (visual-to-analogue scale) were recorded.
Results: There were no significant between-group differences. Between-environment significant differences were found in heart rate (always higher on land), exertion (higher in the water for three exercises and on land for six exercises) and muscle activation (higher on land in 29% and in the water in 5% of comparisons). Pain levels were low, but pain was reported more than twice as frequently on land (7.7% Vs 3.7% of cases).
Limitations: People with high levels of disability and CLBP classification were not included.
Conclusions: People with mild-to-moderate CLBP had similar exercise responses to healthy controls. Aquatic exercise produced sufficient muscle activation, intensity and exertion, and should not be assumed to be less strenuous or less effective in activating trunk and pelvic muscles than exercise on land. These data can be used to inform design and prescription of rehabilitation programmes and interventions.