Effects of Yoga Training on Flexibility and Stress in Secondary School Students: A Randomized Controlled Trial

Abstract

Background: Adolescent secondary school students in Pakistan face a dual burden of sedentary behavior and escalating psychological stress. Yoga, an integrative mind-body discipline comprising physical postures, breathing regulation, and meditative components, has demonstrated efficacy in improving physical flexibility and reducing stress across diverse populations. However, evidence from South Asian secondary school contexts particularly from conservative sociocultural settings such as Peshawar, Khyber Pakhtunkhwa remains absent from the published literature. Objective: This study evaluated the efficacy of a 12-week structured yoga-based training program on physical flexibility (sit-and-reach, shoulder flexibility, hip flexor range of motion) and psychological stress (Perceived Stress Scale-10; PSS-10) among secondary school students in Peshawar District, Pakistan. Methods: A parallel-group, pre-test/post-test randomized controlled trial (RCT) was conducted with 90 students (aged 13–17 years) recruited from six secondary schools (Grades 8–10) across Peshawar District using stratified random sampling. Participants were randomly allocated to a Yoga Group (n = 45) receiving a 12-week, three-sessions-per-week progressive yoga program, or a Control Group (n = 45) maintaining their standard physical education routine. Allocation concealment was maintained using sequentially numbered opaque sealed envelopes, and outcome assessors were blinded to group assignment throughout. Primary outcomes were sit-and-reach flexibility (cm), shoulder flexibility (cm), hip flexor range of motion (°), and PSS-10 score. Assessments were conducted at baseline and post-intervention (Week 12). Between-group differences were analyzed using mixed-model repeated-measures ANOVA, with Cohen’s d for effect size estimation. Intention-to-treat analysis was applied for all participants. Results: The Yoga Group demonstrated significant improvements in all flexibility measures (sit-and-reach: +8.45 cm, d = 2.07; shoulder flexibility: +6.45 cm, d = 1.80; hip flexor ROM: +16.33°, d = 2.02) and a substantial reduction in perceived stress (PSS-10: −8.56 points, d = 1.96) compared to negligible changes in the Control Group (all p < .001). The proportion of students in the high-stress category declined from 26.7% to 4.4% in the Yoga Group versus 24.4% to 22.2% in controls. Flexibility gains were significantly and negatively correlated with stress reduction (r = −0.64 to −0.71, p < .01). Conclusions: A 12-week school-based yoga program produced large, clinically meaningful improvements in physical flexibility and psychological stress among adolescent students in Peshawar, Pakistan, with effect sizes (d = 1.80–2.07 for flexibility; d = 1.96 for perceived stress) among the largest reported in comparable adolescent yoga RCT literature. The program was culturally feasible and operationally deliverable within existing school infrastructure. Integration of structured yoga training into the Khyber Pakhtunkhwa school physical education curriculum is recommended.

Keywords: Yoga; physical flexibility; psychological stress; adolescents; secondary school; Peshawar; Pakistan; randomized controlled trial; PSS-10; sit-and-reach.