Lack of Neuromuscular Origins of Adaptation After a Long-Term Stretching Program

Abstract

Ankle dorsiflexion increased by 42.25% after 6 wk of static stretching, but no significant neurological changes resulted at any point of the study, contrasting current literature. Significant neuromuscular origins of adaptation do not exist in the Ia-reflex-pathway components after a long-term stretching program as currently understood. Thus, any increases in flexibility are the result of other factors, potentially mechanical changes or stretch tolerance.

Stretch training induces unequal adaptation in muscle fascicles and thickness in medial and lateral gastrocnemii

“…5,7,8 One reason increased fascicle length has not been recorded in humans could be the difficulty in administering a stretch to the magnitude required to elicit conformation changes to the muscle fascicles. In human studies, most stretches are applied to the level of tolerance of the subject [12][13][14]16 ; therefore, establishing the degree of stretch intensity is challenged by perception and tolerance. In this study, the stretch intensity was based upon the MVC of each subject, thereby ensuring a load that was initiated at 20% MVC and progressively increased.…”

“…9,10 These animal studies highlight that with sufficient intensity of stretch fascicle length and muscle size increase. 5,7,8,11 In humans, stretch intensity is typically based upon subject tolerance or a pre-established end range of motion [12][13][14][15][16] and this is ostensibly insufficient to stimulate neural and muscle adaptation similar to that observed in animal stretch studies or human resistance or eccentric training.…”

Les étirements musculo-tendineux : des données scientifiques à une pratique raisonnée

“…Il a été suggéré que les étirements pouvaient induire une diminution de l'amplitude des réponses réflexes [18,19], et de telles réponses peuvent mener à des adaptations favorisant l'augmentation de l'amplitude des mouvements lors d'étire-ments répétés [20]. Cependant, ces résultats ne sont pas très robustes avec des modifications de l'excitabilité motoneuronale après l'étirement peu évidentes en position de repos [21,22] ; mais d'autres études [23,24] …”

Acute Passive Static Stretching and Cramp Threshold Frequency

“…1 Static stretching is a common pre-event modality that has historically been used to improve sport performance or limit performance-related injury or both. 17 Static stretching has been reported to alter a-motoneuron pool activity proportionally to the stretching intensity, 18 as evidenced by a decreased H-reflex. Palmieri et al 19 described the H-reflex as a measure of a-motoneuron pool excitability stemming from spinal afferent stimulation.…”

“…The effects of static stretching on the H-reflex have been seen during, immediately after, and up to 60 minutes poststretching. 18,[21][22][23] We accept the proposed mechanism of EAMC as a result of a-motoneuron pool hyperexcitability and elected to investigate static stretching as a perturbation to reduce the excitatory input from the muscle spindles to the amotoneuron pool. To our knowledge, no authors have researched the acute effect of static stretching on CTF.…”