title: Intermittent stretch training of rabbit plantarflexor muscles increases soleus mass and serial sarcomere number.
abstract: In humans, enhanced joint range of motion is observed after static stretch training and results either from an increased stretch tolerance or from a change in the biomechanical properties of the muscle-tendon unit. We investigated the effects of an intermittent stretch training on muscle biomechanical and structural variables. The left plantarflexors muscles of seven anesthetized New Zealand (NZ) White rabbits were passively and statically stretched three times a week for 4 wk, while the corresponding right muscles were used as nonstretched contralateral controls. Before and after the stretching protocol, passive torque produced by the left plantarflexor muscles as a function of the ankle angle was measured. The left and right plantarflexor muscles were harvested from dead rabbits and used to quantify possible changes in muscle structure. Significant mass and serial sarcomere number increases were observed in the stretched soleus but not in the plantaris or medial gastrocnemius. This difference in adaptation between the plantarflexors is thought to be the result of their different fiber type composition and pennation angles. Neither titin isoform nor collagen amount was modified in the stretched compared with the control soleus muscle. Passive torque developed during ankle dorsiflexion was not modified after the stretch training on average, but was decreased in five of the seven experimental rabbits. Thus, an intermittent stretching program similar to those used in humans can produce a change in the muscle structure of NZ White rabbits, which was associated in some rabbits with a change in the biomechanical properties of the muscle-tendon unit.
authors.affiliation: Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada; and Laboratoire de Physiologie et de Biomécanique de la Locomotion, Institute of NeuroScience, Université catholique de Louvain, Louvain-la-Neuve, Belgium Dominique.dejaeger@uclouvain.be.
authors.forename: Dominique
authors.initials: D
authors.lastname: De Jaeger
authors.affiliation: Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada; and.
authors.forename: Venus
authors.initials: V
authors.lastname: Joumaa
authors.affiliation: Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada; and.
authors.forename: Walter
authors.initials: W
authors.lastname: Herzog
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D003094:Collagen / Q000378:metabolism; D064211:Connectin / Q000378:metabolism; D005260:Female; D006614:Hindlimb / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D052580:Muscle Stretching Exercises; D018482:Muscle, Skeletal / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D010805:Physical Conditioning, Animal / Q000502:physiology*; D011817:Rabbits; D016059:Range of Motion, Articular / Q000502:physiology; D012518:Sarcomeres / Q000648:ultrastructure*; D013710:Tendons / Q000502:physiology; D019415:Torque
chemical_list: D064211:Connectin; D003094:Collagen
keywords: muscle properties; muscle stretching; sarcomerogenesis