A stretching program increases the dynamic passive length and passive resistive properties of the calf muscle-tendon unit of unconditioned younger women
ABSTRACT This study examined the effects of a 6-week stretching program on the dynamic passive elastic properties of the calf muscle-tendon unit (MTU) of unconditioned younger women. After random assignment of 12 women (age 18-31 years) to a stretching group (SG) or to a control group (CG), six subjects in the SG and four subjects in the CG completed the study. For the initial tests, a Kin-Com dynamometer moved the ankle from plantarflexion to maximal dorsiflexion (DF) with negligible surface EMG activity in the soleus, gastrocnemius and tibialis anterior muscles. Angular displacement, passive resistive torque, area under the curve (passive elastic energy) and stiffness variables were reduced from the passive DF torque curves. The SG then completed ten static wall stretches held 15 s each, five times a week for 6 weeks, the CG did not. The tests were repeated and the changes between the tests and retests were examined for group differences (Mann-Whitney U). The SG had significant increases in the maximal passive DF angle (7 degrees +/- 4 degrees ), maximal passive DF torque (11.2 +/- 8.3 N m), full stretch range of motion (23 degrees +/- 24 degrees ), full stretch mean torque (3.4 +/- 2.1 N m), and area under the full stretch curve (22.7 +/- 23.5 degrees N m) compared to the CG (P < or = 0.019). The passive stiffness did not change significantly. The results showed that a stretching program for unconditioned calf MTUs increased the maximal DF angle and length extensibility, as well as the passive resistive properties throughout the full stretch range of motion. The adaptations within the calf MTU provide evidence that stretching enhances the dynamic passive length and passive resistive properties in unconditioned younger women.
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- "), Immobilization in lengthened position (Tabary et al. 1972; Pontén and Fridén 2008; Williams and Goldspink 1971; Pattullo et al. 1992; Goldspink and Scutt 1992), stretch regimen (Nordez et al. 2009; Gajdosik et al. 2007; Nordez et al. 2006; LaRoche and Connolly 2006; Nakamura et al. 2012; Reid and Mcnair 2004; Goldspink 1999) Sarcomeres in series ↑ (Makarov et al. 2009; Boakes et al. 2007; Lindsey et al. 2002; Simpson and Williams 1995; Williams and Goldspink 1971; Tabary et al. 1972; De Deyne 2002) Sarcomere length ↑ (Makarov et al. 2009; Elsalanty et al. 2007) Slower MHC ↑ (De Deyne et al. 1999; Goldspink and Scutt 1992) Fiber length ↑ (Makarov et al. 2009; Elsalanty et al. 2007; Lindsey et al. 2002) Slower fiber type ↑ (Pattullo et al. 1992; De Deyne et al. 1999) Passive stiffness ↑ (Reid and Mcnair 2004; Williams et al. 1998), mixed (Nordez et al. 2006), NC (LaRoche and Connolly 2006; Gajdosik et al. 2007) ECM ↑ (Pontén and Fridén 2008) Collagen ↑ (Williams et al. 1998) Pennation angle ↓ (Elsalanty et al. 2007) Fascicle length ↑ (Boakes et al. 2007; Elsalanty et al. 2007; Williams et al. 1998; Simpson and Williams 1995) "
ABSTRACT: Skeletal muscle undergoes continuous turnover to adapt to changes in its mechanical environment. Overload increases muscle mass, whereas underload decreases muscle mass. These changes are correlated with, and enabled by, structural alterations across the molecular, subcellular, cellular, tissue, and organ scales. Despite extensive research on muscle adaptation at the individual scales, the interaction of the underlying mechanisms across the scales remains poorly understood. Here, we present a thorough review and a broad classification of multiscale muscle adaptation in response to a variety of mechanical stimuli. From this classification, we suggest that a mathematical model for skeletal muscle adaptation should include the four major stimuli, overstretch, understretch, overload, and underload, and the five key players in skeletal muscle adaptation, myosin heavy chain isoform, serial sarcomere number, parallel sarcomere number, pennation angle, and extracellular matrix composition. Including this information in multiscale computational models of muscle will shape our understanding of the interacting mechanisms of skeletal muscle adaptation across the scales. Ultimately, this will allow us to rationalize the design of exercise and rehabilitation programs, and improve the long-term success of interventional treatment in musculoskeletal disease.Biomechanics and Modeling in Mechanobiology 09/2014; 14(2). DOI:10.1007/s10237-014-0607-3 · 3.25 Impact Factor
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- "Stretching routines are an integral part of fitness and applied in sport, recreational and clinical environments (Magnusson et al., 1996; Gajdosik et al., 2007; Morse et al., 2008). Despite the widespread use of many different stretching modalities, limited knowledge exists regarding its mechanisms and efficacy . "
ABSTRACT: The present study determined human skeletal muscle oxygenation dynamics during and after a single bout of self-administered stretching (SAS) of the plantar flexors. Nine healthy recreationally fit men (n = 7; age = 25.7 yrs) and women (n = 2; age = 23.5 yrs) performed two protocols: 1) one bout of SAS for 4 min, and 2) one bout of moderate intensity cycling for 4 min. We used near infrared spectroscopy to measure changes in muscle deoxygenated hemoglobin-myoglobin ([HHb]) and blood volume ([Hbtot]) of gastrocnemius medialis muscle before, during and after stretching. The SAS caused an increase (P < 0.05) in [HHb] during stretching between 60 and 240 s relative to baseline, but not at 30 s. No significant difference was found for [Hbtot] at any time interval during SAS. Furthermore, the increase in local blood flow (suggested by [Hbtot] changes) was found to be significantly increased relative to baseline at 1, 5 and 10 min after SAS, thus providing novel evidence for a post-stretch hyperemia. No significant interaction for [HHb] was found between stretching and cycling conditions, suggesting that the metabolic disturbance during stretching closely resembles moderate intensity exercise. These findings suggest that a single self-administered stretch for 60 s can produce a substantial microcirculatory event and that blood flow may be enhanced for up to 10 min after stretching.Clinical Physiology and Functional Imaging 09/2014; DOI:10.1111/cpf.12205 · 1.33 Impact Factor
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- "Results from quality assessment are presented in Table 1. Of the studies selected for inclusion, 13 featured a control group [2,3,5,12,16,18,19,21],[23,25,29,31,32,38]. Sixteen of the included studies randomly assigned participants to treatment groups [1-3,5,12,14-16,18,19,21,23],[25,29,31,32], nine studies featured blinding of the participants, assessors or therapists [1,2,12,13,16,19,21,31], and 13 studies reported on the reliability of the measures used [1,3,5,12,14,16,23,25],[27,29-32]. "
ABSTRACT: Ankle joint equinus, or restricted dorsiflexion range of motion (ROM), has been linked to a range of pathologies of relevance to clinical practitioners. This systematic review and meta-analysis investigated the effects of conservative interventions on ankle joint ROM in healthy individuals and athletic populations. Keyword searches of Embase Medline Cochrane and CINAHL databases were performed with the final search being run in August 2013. Studies were eligible for inclusion if they assessed the effect of a non-surgical intervention on ankle joint dorsiflexion in healthy populations. Studies were quality rated using a standard quality assessment scale. Standardised mean differences (SMDs) and 95% confidence intervals (CIs) were calculated and results were pooled where study methods were homogenous. Twenty-three studies met eligibility criteria, with a total of 734 study participants. Results suggest that there is some evidence to support the efficacy of static stretching alone (SMDs: range 0.70 to 1.69) and static stretching in combination with ultrasound (SMDs: range 0.91 to 0.95), diathermy (SMD 1.12), diathermy and ice (SMD 1.16), heel raise exercises (SMDs: range 0.70 to 0.77), superficial moist heat (SMDs: range 0.65 to 0.84) and warm up (SMD 0.87) in improving ankle joint dorsiflexion ROM. Some evidence exists to support the efficacy of stretching alone and stretching in combination with other therapies in increasing ankle joint ROM in healthy individuals. There is a paucity of quality evidence to support the efficacy of other non-surgical interventions, thus further research in this area is warranted.Journal of Foot and Ankle Research 11/2013; 6(1):46. DOI:10.1186/1757-1146-6-46 · 1.83 Impact Factor