Prophylactic stretching does not reduce cramp susceptibility

Introduction: Some clinicians advocate stretching to prevent muscle cramps. It is unknown whether static or proprioceptive neuromuscular facilitation (PNF) stretching increases cramp threshold frequency (TF_c), a quantitative measure of cramp susceptibility. Methods: Fifteen individuals completed this randomized, counterbalanced, cross-over study. We measured passive hallux range of motion (ROM) and then performed 3 minutes of either static stretching, PNF stretching (hold–relax—with agonist contraction), or no stretching. ROM was reassessed and TF_c was measured. Results: PNF stretching increased hallux extension (pre-PNF 81 ± 11°, post-PNF 90 ± 10°; P < 0.05) but not hallux flexion (pre-PNF 40 ± 7°, post-PNF 40 ± 7°; P > 0.05). Static stretching increased hallux extension (pre-static 80 ± 11°, post-static 88 ± 9°; P < 0.05) but not hallux flexion (pre-static 38 ± 9°, post-static 39 ± 8°; P > 0.05). No ROM changes occurred with no stretching (P > 0.05). TF_c was unaffected by stretching (no stretching 18 ± 7 Hz, PNF 16 ± 4 Hz, static 16 ± 5 Hz; P = 0.37). Discussion: Static and PNF stretching increased hallux extension, but neither increased TF_c. Acute stretching may not prevent muscle cramping. Muscle Nerve 57: 473–477, 2018.