Recovery from exercise-induced desaturation in the paraspinal muscles in idiopathic scoliosis

Study Design. A study using near-infrared light spectroscopy to measure recovery from exercise-induced desaturation in the paraspinal muscles of patients with idiopathic scoliosis. Objectives. To measure oxygenation of the paraspinal muscles and obtain differences between the convex and concave sides. Summary of Background Data. Authors of previous studies have reported that some patients experience pain on the convex side of the paraspinal muscles. The muscles on the convex side are more stretched and stressed than those on the concave side. The current authors investigated the degree of stress by measuring oxygenation and blood volume changes. Methods. Paraspinal muscle spectral properties at L3 were investigated using near-infrared light spectroscopy. Thirty-six patients (8 men and 28 women) underwent this procedure. To assess a level of peripheral adaptations to exercise, the half- time of Oxyhemoglobin/Myoglobin recovery was measured, which indicates the recovery from energy deficit after exercise. Results. The average half-time recovery on the convex side was 3.38 seconds (range, 1.5-5.5 seconds), whereas that on the concave side was 1.51 seconds (range, 0.7-4.0 seconds). The average difference between the convex side and the concave side was 1.87 seconds (range, 0.9-3.5 seconds). Conclusions. Half-time recovery on the convex side in the patients with idiopathic scoliosis was slower than that in healthy adults (P < 0.05). Half-time recovery on the concave side in such patients was faster than that on the convex side (P < 0.01). The authors consider half-time recovery an indication of back muscle stress.