The Effect of Eight Weeks of Aquatic Training on the Kinematic and Continuous Relative Phase of Trunk-Pelvis During Gait in Patients with Chronic Back Pain

Low back pain is one of the most common disorders that affect one's functional ability in daily life and workplace activities, as well as their general health and quality of life. The motion range and the trunk-pelvis coordination are important kinematic variables that seem to be affected by low back pain. Currently, aquatic training is one of the popular methods to treat patients with low back pain. This study aims to investigate the effect of eight weeks of aquatic training on the kinematic and continuous relative phase trunk-pelvis coordination during gait in patients with chronic back pain. In this quasi-experimental and causal-comparative study, 50 subjects with chronic back pain were divided into control and experimental groups. Noraxon IMU system was used to measure the pelvis and trunk kinematic variables during walking before and after aquatic training. The angular information of the pelvis and trunk was extracted with IMU software. Subsequently, the range of motion and continuous relative phase index were calculated. Following the pretest, the participants underwent three days a week of water walking training lasting eight weeks. Gait speed was increased after each week of gait training. The control group continued their daily activities after the pretest. For statistical analysis, the dependent t-test was used for within-group comparison, and the independent t-test was used for between-group comparison (P≤0.05). The results of this study showed that aquatic training reduces the trunk's range of motion (P<0.05). Aquatic training increased the coordination between the trunk and pelvis, which indicates greater coordination between the trunk and pelvis during walking (P<0.05). Moreover, the variability of coordination decreased significantly within and between groups after training in water (P<0.05). According to the current study's results, eight weeks of water gait training at different speeds reduces the range of motion of the trunk due to the features of aquatic training, such as buoyancy and flow resistance. This decrease in the range of motion balances the movement of the trunk around the pelvis, and consequently, the coordination between these two segments increases. On the other hand, the results of this study pointed to the greater stability of walking of patients with back pain after performing the exercise, indicating that the walking pattern in high repetitions is closer to normal gait.