Preserving sarcomere number after tenotomy requires stretch and contraction

Abstract

Passive stretch alone does not prevent shortening adaptation. Contraction is required in combination with stretch to preserve the number of sarcomeres in series. The combination of stretch and contraction is necessary to maintain proper muscle fiber length.

Efficacy of stretching in physiotherapy and sports

“…The key to understanding muscle length changes as an adaptive process seems to lie in muscular activity in the course of immobilization. 21 Animal testing has provided a chance of comparing the effects of passive stretching and passive stretching with contraction on the soleus muscle length after the Achilles tendonectomy. Passively stretching the muscle for 20 minutes daily, under anaesthesia, did not have any impact on reducing the number of sarcomeres.…”

Standing Programs to Promote Hip Flexibility in Children With Spastic Diplegic Cerebral Palsy

“…15,16 Evidence suggests that the exclusive application of passive stretches is not enough to prevent muscles from shortening. 5 However, stretches combined with isometric contractions have resulted in significant increases in joint ROM and extensibility. 5 According to Fowless contraction is required in combination with a stretch to preserve the number of sarcomeres, and maintain proper muscle fiber length.…”

“…5 However, stretches combined with isometric contractions have resulted in significant increases in joint ROM and extensibility. 5 According to Fowless contraction is required in combination with a stretch to preserve the number of sarcomeres, and maintain proper muscle fiber length. 17 In studies of children with spasticity, some evidence indicates that sustained stretching is preferable to improve ROM and reduce spasticity in joints and muscles, respectively, when compared with manual stretching.…”

Stretching adversely modulates locomotor capacity following spinal cord injury via activation of nociceptive afferents.

“…did not prevent the shortening adaptation (loss of sarcomeres) while the induction of the contraction by electrical stimulation of the stretched muscle significantly increased the number of sarcomeres [334]. Furthermore, stretching does not prevent the development of knee contracture in the rats with a thoracic spinal cord transection [72].…”

“…The failure to observe similar effects of stretching on muscle properties as reported by Williams et al, in rats likely results from an inadvertent omission of subtle observations such as muscle contractions occurring simultaneously with the stretching applied to the cast-immobilized limb. As it became apparent in later more carefully designed studies, muscle contraction during stretching is the key to the increased number of sarcomeres, as passive stretching alone does not prevent shortening of the immobilized muscle [334]. Nevertheless, stretching has become a leading therapy for the treatment of contractures as a result of overly enthusiastic extrapolation of the misleading results to human subjects without proper clinical trials to confirm the effectiveness of stretching.…”