Sample size calculation was performed to eliminate type II error. Sample size was calculated using the G*Power 3.1.3 (Heinrich-Heine-University) software [5]. Significance level was set at 0.05 and a medium effect size (0.25) with two-sided calculation was used. Effect size contains the magnitude of difference between groups and values of 0.25, indicates medium effect of treatment [6]. By these assumptions, to achieve a power of 0.80, a sample size of 36 participants was necessary. Conservatively, 48 subjects were recruited since we expected a 20% dropout rate due to the demanding nature of the intervention program and our previous experience.