**4.1. Cobb angle**

The SBP exercise improved the Cobb angle very significantly. This is consistent with previous findings [17, 20, 21, 31, 32] in AIS patients. Curves of adult AIS patients can be reduced through multi-modal rehabilitation approaches [13, 14, 16]. SEAS (Scientific Exercise Approach to Scoliosis Exercises) [15, 17], Schroth [18] and side shift exercises [31] have been reported to reduce curve severity in adult AIS patients. Negrini et al. reported an adult AIS female, aged 25 with a double curve, treated by SEAS for 1 year. The main lumbar curve reduced from 47 to 28.5° [15]. Similarly, Yang et al. reported an AIS adult female with thoracic Cobb angle of 20.51°, treated by stretching, SBP, and strengthening exercises. In 8 weeks, the Cobb angle reduced to 16.35° [18]. Side shift exercises were also reported to reduce the Cobb angle of 69 patients with a mean age of 16.3 years. After an average follow up of 4.2 years, the mean Cobb angle reduced from 31.5 to 30.3° [31]. A retrospective cohort study also showed that curves of adult AIS patients can be reduced through SEAS. After 2 years of intervention, 68% experienced an improvement which averaged 4.6°. On average, the thoracolumbar curve reduced by 3° and the lumbar curve reduced by 3.6°. The improvement, however, was not statistically significant [17]. In comparison, our results showed that the improvement rate was 33.3%, when 6° curve reduction was regarded as an improvement. The average improvement was 4.2°. The findings closely matched that of the study by Negrini et al. [17]. It has, however, to be noted that not all of the patients in the present study had adult AIS.

Interestingly, nonscoliosis specific exercises have also been found to improve the Cobb angle in AIS and DLS patients [32]. Fishman et al. found that performing side plank yoga pose with the curve convexity facing downwards, for as long as possible once daily for 3–22 months resulted in an improvement of the Cobb angle [32]. The side plank yoga pose improved the Cobb angle in the 12 patients with DLS, from an average of 50.4–33.1° [32]. Yet, the study has a number of weaknesses and limitations. The study included patients with Cobb angle as small as 6°. Strictly speaking, these patients should not be regarded as suffering from scoliosis. Also, a reduction of 3° Cobb was regarded as improvement, though curve improvement is defined as a reduction of 6° Cobb angle [30].
