Reproducibility of Acute Changes in Range of Motion Following Short-Term Static Stretching of the Hamstrings and Gastrocnemius.

Background and

Objectives

Acute responses to exercise interventions may vary within individuals across repeated exposures, potentially limiting the interpretation of individuals as "responders" or "non-responders". This study investigated whether acute changes in range of motion following short-term static stretching are reproducible within individuals.

Methods

Twenty-six healthy young adults completed two identical sessions separated by one week. Flexibility was assessed before and after static stretching using the Sit-and-Reach Test (SRT) and ankle dorsiflexion range of motion (ADF ROM). The intervention consisted of three 30 s static stretches for the hamstrings and gastrocnemius.

Results

Baseline measurements showed excellent reproducibility (SRT: ICC = 0.98; ADF ROM: ICC = 0.95). SRT performance and ADF ROM increased significantly after stretching (p < 0.001), with no evidence of a systematic difference in the mean response between visits (time × visit interactions: p > 0.05). Reproducibility of individual pre-to-post change scores was moderate by point estimate but imprecisely estimated (SRT: ICC = 0.74; 95% CI: 0.50-0.88; ADF ROM: ICC = 0.57; 95% CI: 0.25-0.78).

Conclusions

Individual change scores showed limited reproducibility. The design cannot separate measurement error, normal day-to-day variation, and variability specifically attributable to the stretching response. Classifying individuals as "responders" or "non-responders" based on a single acute stretching session should therefore be approached with caution.