Changes in passive tension after stretch of unexercised and eccentrically exercised human plantarflexor muscles

• Published in: Experimental brain research Vol. 193; no. 4; pp. 545 - 554
• Main Authors: Reisman, Simone, Allen, Trevor J, Proske, Uwe
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Berlin/Heidelberg : Springer-Verlag 01.03.2009; Springer-Verlag; Springer; Springer Nature B.V
• Subjects: Analysis of Variance; Ankle; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Elbow; Electromyography; Experiments; Female; Fundamental and applied biological sciences. Psychology; Humans; Injuries; Male; Mechanical properties; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Muscle Contraction; Muscle Strength - physiology; Muscle Stretching Exercises; Muscle Tonus; Muscle, Skeletal - physiology; Neurology; Neurosciences; Pain - physiopathology; Pain Measurement; Pain Threshold - physiology; Research Article; Strain gauges; Striated muscle. Tendons; Torque; Vertebrates: nervous system and sense organs; Vertebrates: osteoarticular system, musculoskeletal system; Young Adult; Thixotropy; Passive tension; Pain; Eccentric exercise; Warm-up; Human; Cross bridge; Mechanical properties; Strategy; Striated muscle; Muscle contraction; Eccentric movement
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/s00221-008-1657-5

The study measured the effect of stretch on passive mechanical properties in unexercised and eccentrically exercised plantarflexor muscles, to obtain insight into how stretch might serve athletes as a warm-up strategy. Passive torque, voluntary contraction strength and muscle soreness were measured before and after a large amplitude stretch given before and after a period of eccentric exercise and at 0, 1, 2 and 24 h later. Stretch of the unexercised muscle led to a 20% fall in passive torque which recovered within an hour. About 40% of the fall could be recovered immediately with a voluntary contraction. After eccentric exercise there was a rise in passive torque by 20% at 2 h post-exercise. This rise was postulated to result from an injury contracture in muscle fibres damaged by the exercise. It was accompanied by a fall in maximum voluntary torque and the development of muscle soreness at 24 h. Stretch of the exercised muscle led to a fall in passive torque and rise in pain threshold. It is proposed that in response to a stretch there is a fall in passive tension in the muscle due to stable cross-bridges in sarcomeres which could be recovered with a voluntary contraction and an additional component attributable to the elastic filament, titin. The size of the fall was not significantly different between exercised and unexercised muscle. These observations provide a physiological basis for the effects of passive stretches on skeletal muscle and help to explain why they are used as a popular warm-up strategy.