Neuromuscular factors influencing the maximum stretch limit of the human plantar flexors
- 1 November 2012
- journal article
- research article
- Published by American Physiological Society in Journal of Applied Physiology
- Vol. 113 (9), 1446-1455
- https://doi.org/10.1152/japplphysiol.00882.2012
Abstract
Maximum joint range of motion is an important parameter influencing functional performance and musculoskeletal injury risk. Nonetheless, a complete description of the muscle architectural and tendon changes that occur during stretch and the factors influencing maximum range of motion is lacking. We measured muscle-tendon elongation and fascicle lengthening and rotation sonographically during maximal plantar flexor stretches in 21 healthy men. Electromyogram (EMG) recordings were obtained synchronously with ultrasound and joint moment data, and H-reflex measurements were made with the ankle at neutral (0°) and dorsiflexed (50% maximal passive joint moment) positions; the maximum H amplitude (normalized to maximum M-wave amplitude; Mmax) and H-amplitude elicited at a stimulation intensity that evoked 10% Mmaxwere obtained. Maximal stretch was accomplished through significant muscle (14.9%; 30 mm) and tendon lengthening (8.4%; 22 mm). There were similar relative changes in fascicle length and angle, but planimetric modeling indicated that the contribution of fascicle rotation to muscle lengthening was small (<4 mm). Subjects with a greater range of motion showed less resistance to stretch and a greater passive joint moment at stretch termination than less flexible subjects (i.e., greater stretch tolerance). Also, greater fascicle rotation accompanied muscle elongation (9.7 vs. 5.9%) and there was a greater tendon length at stretch termination in more flexible subjects. Finally, a moderate correlation between the angle of EMG onset and maximum range of motion was obtained ( r = 0.60, P < 0.05), despite there being no difference in H-reflex magnitudes between the groups. Thus clear differences in the neuromuscular responses to stretch were observed between “flexible” and “inflexible” subjects.Keywords
This publication has 54 references indexed in Scilit:
- Plantarflexor stretch training increases reciprocal inhibition measured during voluntary dorsiflexionJournal of Neurophysiology, 2012
- Plasticity of human Achilles tendon mechanical and morphological properties in response to cyclic strainJournal of Biomechanics, 2010
- Regular stretch does not increase muscle extensibility: a randomized controlled trialScandinavian Journal of Medicine & Science in Sports, 2010
- The relative lengthening of the myotendinous structures in the medial gastrocnemius during passive stretching differs among individualsJournal of Applied Physiology, 2009
- Influence of concentric and eccentric resistance training on architectural adaptation in human quadriceps musclesJournal of Applied Physiology, 2007
- Adaptational responses of the human Achilles tendon by modulation of the applied cyclic strain magnitudeJournal of Experimental Biology, 2007
- Risk Factors for Injuries in FootballThe American Journal of Sports Medicine, 2004
- Effect of Static Stretching on Prevention of Injuries for Military RecruitsMilitary Medicine, 2003
- Altered reflex sensitivity after repeated and prolonged passive muscle stretchingJournal of Applied Physiology, 1999
- Flexibility of the shoulder joint measured as range of abduction in a large representative sample of men and women over 65 years of ageEuropean Journal of Applied Physiology, 1989