Electromyographic and haemodynamic activities in lumbar muscles during bicycle ergometer exercise and walking

Although bicycle ergometer exercise and walking are recommended as aerobic exercise for patients with lumbago, little research has been done to examine the muscular activities and circulatory dynamics during these exercises. In this study, we aimed at obtaining basic information on aerobic exercises effective for patients with lumbago by investigating the activities and circulatory dynamics of their lumbar muscles during bicycle ergometer exercise and walking. As subjects, we selected 10 healthy adults (23.7 +/- 3.4 years old) with no anamnestic history of lumbago. The measurement conditions were 4 types of exercise: walking (4.0 km/h); 25W, 50W and 75W bicycle ergometer exercises. The activities of the lumbar muscles during the exercises were measured by a surface electromyograph, and percent of MVC was calculated from the maximal voluntary contraction (MVC). With regard to the circulatory dynamics of the lumbar muscles, we measured oxygenated hemoglobin (Oxy-Hb) and deoxygenated hemoglobin (Deoxy-Hb) before and after the exercises with near infrared spectroscopy (NIRS). The change rates during the exercises were calculated based on the values before the exercises. Paired t test was employed to analyse the comparison of the circulatory dynamics of the lumbar muscles between, before and during the exercises. With respect to the comparison of the change rates of the muscular activities and circulatory dynamics among each of the exercises, we employed the one-way analysis of variance (ANOVA) (p < .05). The lumbar muscular activities during the walking were significantly higher than those during the bicycle ergometer exercise were at each load level. The Oxy-Hb increased significantly during the 25W and 50W bicycle ergometer exercises, as opposed to before the exercises. It showed a tendency to decrease during the 75W bicycle ergometer exercise and walking, but not significant. The change rate of the Oxy-Hb during the 25W bicycle ergometer exercise indicated a higher value than that of the other exercises. The Deoxy-Hb, on the other hand, declined significantly in every exercise compared with those before the exercises, with no significant differences in the change rates between each of the exercises. Bicycle ergometer exercise has been suggested as an aerobic exercise permitting as much oxygen uptake as walking does, with fewer loads on lumbar muscles and less likelihood of inducing a hypoxic state on lumbar muscles.