Intermittent stretch training of rabbit plantarflexor muscles increases soleus mass and serial sarcomere number

Abstract

De Jaeger D, Joumaa V, Herzog W. Intermittent stretch training of rabbit plantarflexor muscles increases soleus mass and serial sarcomere number. J Appl Physiol 118: 1467-1473, 2015. First published April 2, 2015 doi:10.1152/japplphysiol.00515.2014.-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. sarcomerogenesis; muscle properties; muscle stretching REGULARLY PRACTICED by humans, passive static stretching systematically and significantly enhances specific joint range of movement (ROM) (9, 26). One single 30-s stretch applied 3 days/wk for 4 wk appears to be enough to significantly increase knee extension ROM in young adult subjects with tight hamstrings (7). However, what causes this enhanced ROM, an increased stretch tolerance or a change in the biomechanical properties of the muscle-tendon unit, is not clear (32).In humans, the effects of a stretching program on muscletendon biomechanical properties are studied through the changes in passive torque-angle curves measured before and after the stretching program. Published results regarding these curves are neither numerous nor consistent and seem to depend on the stretched muscle group or on the stretching protocol.Contrasting results have been obtained when different muscle groups were exposed to the same stretching program. Different results are obtained when different stretching programs are used on the same muscle group. Passive torque and stiffness, measured at ...

Titin force enhancement following active stretch of skinned skeletal muscle fibres

“…HYP concentration was determined by the reaction of oxidized HYP with 4-(dimethylamino) benzaldehyde (DMAB), resulting in a colorimetric product (560 nm) proportional to the concentration of HYP present. Measured HYP mass (μg) was used to calculate approximate collagen mass using the equation: collagen mass=7.25×measured mass of HYP (De Jaeger et al, 2015;Woessner, 1961). Collagen mass is expressed as a percentage normalized to the mass of pooled control (n=6) and mutant (n=5) skinned fibres.…”

Phase‐contrast hard X‐ray microscopy using synchrotron radiation for the properties of skeletal muscle in mouse hind limbs

“…The soleus is a muscle that has a spindle and long shape. It makes a plantar flexion of the ankle joint, plays an important role in walking, and is used for analyzing the muscle tissue in animals (De Jaeger, Joumaa, & Herzog, ). The image obtained in this study is the middle part of the muscle belly, which in Figure is marked in black, and indicated by the square‐dotted line, except for the part of the soleus tendon at both ends of the image obtained in this study.…”

Does Stretching Have Long-Term Effects on Muscle Performance? A Clinical Commentary

“…Normally, there are three main mechanisms used to explain an increase in muscle length: sarcomerogenesis [24,25], increase in stretching tolerance (increase in passive torque at end ROM) [26,27] and decrease in MTU stiffness [28].…”

“…If there had been any adaptations within the muscle cell, it is probable that some improvement in performance would have been observed. Indeed, sarcomerogenesis is a real adaptation [24] and it has been observed in animal studies [24] and muscle lengthening approaches [36]. However, the duration and the intensity of the flexibility training necessary to induce such adaptation remain an issue of debate.…”