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Optimal stretching dose for improving range of motion in non-athletes and athletes with hamstring shortening: a
Guillermo Mendez-Rebolledo1, Joaquín Salazar-Méndez2, Felipe Araya-Quintanilla3
1Laboratorio de Investigación Somatosensorial y Motora, Escuela de Kinesiología, Facultad de Salud, Universidad Santo Tomás, Av Circunvalación Norte, 1855, 3460000 Talca, Chile.
Background:
Hamstring stretching is widely used to improve range of motion (ROM), but the optimal stretching dose remains unclear.
Objective:
To determine the dose-response relationship between total stretching volume and ROM gains in healthy people with hamstring shortening, whether athletes or non-athletes, differentiating between stretching modalities. The secondary objective was to analyze dose-response patterns for single-session and post-program effects.
Methods:
MEDLINE (PubMed), Web of Science, SPORTDiscus, CINAHL, and SCOPUS were searched. Randomized controlled and crossover trials including healthy participants without active musculoskeletal injury and with clinically confirmed hamstring shortening were included. Outcomes were ROM using active knee extension (AKE), passive knee extension (PKE), and straight leg raise (SLR) tests. Random-effects meta-analyses pooled mean differences, and dose-response meta-analyses assessed associations between total stretching time and ROM change. Risk of bias (RoB 2) and certainty (GRADE) were evaluated.
Results:
Eighty-four studies were included (non-athlete, n = 3008; athletes, n = 1059). In non-athletes, static stretching improved AKE (mean differences, MD 9.03°), PKE (MD 8.44°), and SLR (MD 12.11°) vs no intervention. Proprioceptive neuromuscular facilitation (PNF) improved AKE vs no intervention (MD 10.10°) and showed a small advantage over static stretching (MD 3.18°). In athletes, static stretching improved AKE vs no intervention (MD 9.00°). Dose-response curves were nonlinear. For static stretching, a brief single-session dose (1.5 min) did not exceed the minimal detectable change (12°) for AKE. In contrast, repeated stretching delivered over at least 1 week, with a cumulative volume of 70 min, was more likely to exceed this threshold. Most studies had high/some concerns risk of bias, yielding very low-to-high certainty across outcomes.
Conclusion:
ROM gains followed a nonlinear, modality-specific dose-response pattern in people with hamstring shortening. Repeated stretching programs lasting at least 1 week were more likely than a brief single session to produce meaningful ROM improvements.
Prospero Id:
CRD42024535372.
