Range of motion, neuromechanical, and architectural adaptations to plantar flexor stretch training in humans

Article


Blazevich, A., Cannavan, D., Waugh, C., Miller, S., Thorlund, J., Aagaard, P. and Kay, A. 2014. Range of motion, neuromechanical, and architectural adaptations to plantar flexor stretch training in humans. Journal of Applied Physiology. 117 (5), pp. 452-462. https://doi.org/10.1152/japplphysiol.00204.2014
TypeArticle
TitleRange of motion, neuromechanical, and architectural adaptations to plantar flexor stretch training in humans
AuthorsBlazevich, A., Cannavan, D., Waugh, C., Miller, S., Thorlund, J., Aagaard, P. and Kay, A.
Abstract

The neuromuscular adaptations in response to muscle stretch training have not been clearly described. In the present study, changes in muscle (at fascicular and whole muscle levels) and tendon mechanics, muscle activity, and spinal motoneuron excitability were examined during standardized plantar flexor stretches after 3 wk of twice daily stretch training (4 × 30 s). No changes were observed in a nonexercising control group (n = 9), however stretch training elicited a 19.9% increase in dorsiflexion range of motion (ROM) and a 28% increase in passive joint moment at end ROM (n = 12). Only a trend toward a decrease in passive plantar flexor moment during stretch (−9.9%; P = 0.15) was observed, and no changes in electromyographic amplitudes during ROM or at end ROM were detected. Decreases in Hmax:Mmax (tibial nerve stimulation) were observed at plantar flexed (gastrocnemius medialis and soleus) and neutral (soleus only) joint angles, but not with the ankle dorsiflexed. Muscle and fascicle strain increased (12 vs. 23%) along with a decrease in muscle stiffness (−18%) during stretch to a constant target joint angle. Muscle length at end ROM increased (13%) without a change in fascicle length, fascicle rotation, tendon elongation, or tendon stiffness following training. A lack of change in maximum voluntary contraction moment and rate of force development at any joint angle was taken to indicate a lack of change in series compliance of the muscle-tendon unit. Thus, increases in end ROM were underpinned by increases in maximum tolerable passive joint moment (stretch tolerance) and both muscle and fascicle elongation rather than changes in volitional muscle activation or motoneuron pool excitability.

Keywordsmuscle stiffness; tendon stiffness; stretch tolerance; flexibility; elasticity
Research GroupBiomechanics at the London Sport Institute
PublisherAmerican Physiological Society
JournalJournal of Applied Physiology
ISSN8750-7587
Publication dates
Print01 Sep 2014
Online19 Jun 2014
Publication process dates
Deposited14 Jan 2015
Accepted13 Jun 2014
Submitted03 Mar 2014
Output statusPublished
Digital Object Identifier (DOI)https://doi.org/10.1152/japplphysiol.00204.2014
LanguageEnglish
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