Impact of yoga asanas on flexion and relaxation phenomenon in women with chronic low back pain: Prophet model prospective study

Chronic nonspecific low back pain (NSLBP) is a prevalent condition with socioeconomic and healthcare challenges. The flexion–relaxation phenomenon (FRP) evaluation is a valid clinical tool for low back pain (LBP) assessment. Yoga, a holistic mind–body practice, has been explored as an LBP intervention. This study aimed to evaluate the impact of yoga asanas on the FRP in women with NSLBP. The study included healthy and chronic NSLBP females who underwent an eight-session yoga asanas program, with the first session conducted in-clinic and the rest delivered with tele-approach. Outcome measures included pain intensity, flexion–relaxation ratio (FRR), and trough surface electromyography collected during trunk maximum voluntary flexion (MVF). The study included 11 healthy and 10 NSLBP women. Repeated measures test in chronic NSLBP group showed a significant decrease in pain intensity after the 4 weeks follow-up (visual analog scale [VAS]: 6.80 ± 1.48 vs. 3.30 ± 1.25; p < 0.001) and an FRR improvement after the intervention (5.12 ± 0.93 vs. 9.49 ± 0.92; p < 0.001). VAS and FRR effect sizes were 0.77 and 0.47, respectively. Therefore, we performed a Prophet evaluation to assess FRR trends, finding a growth rate (k) of 0.405 ± 0.448, with a forecast 1 month after the end of the intervention approaching the trend line of the control group. The findings suggested that tele-yoga asana might have a positive impact on pain intensity and the FRP in chronic LBP. Further research is warranted to confirm the long-term effects of yoga for managing LBP.