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This study compared adaptations in fascicle lengths, pennation angles, and muscle thickness of the lateral and medial gastrocnemii in response to 6 weeks of stretch training. The nondominant plantar flexors of 11 males were stretched five times per week for 6 weeks and compared with the contralateral leg and a nonstretched control group of 10 males. During stretch training, instantaneous electromyography was utilized to ensure passive muscle stretch. At baseline, week three, week six and 1 week after the conclusion of stretch training, ultrasound was used to measure fascicle lengths, pennation angles, muscle thickness of the lateral gastrocnemius and medial gastrocnemius, and Achilles tendon thickness and length. Plantar flexion torque was measured, and voluntary activation was assessed. Muscle thickness increased 5.6% after 6 weeks of stretch training ( P=.009). The fascicles in the lateral gastrocnemius lengthened to a greater extent than the medial. Overall, fascicles lengthened 25% ( P<.001) in the muscle tendon junction and 5.1% ( P<.001) in the muscle belly. Pennation angles were unchanged in the medial gastrocnemius but decreased in the lateral gastrocnemius 7.1% ( P=.02). There was no change in maximal voluntary contraction, voluntary activation, tendon length, or thickness. This study demonstrates that stretch training is a viable modality to alter muscle architecture of the human gastrocnemius through lengthening of muscle fascicles, decreasing pennation angles, and increasing muscle thickness, albeit adaptations are unequal between the lateral and medial heads. [ABSTRACT FROM AUTHOR]

Repetitive strain or 'overuse' is thought to be a major factor contributing to the development of tendinopathy. The aims of our study were to develop a novel cyclic loading system, and use it to investigate the effect of defined loading conditions on the mechanical properties and gene expression of isolated tendon fascicles. Tendon fascicles were dissected from bovine-foot extensors and subjected to cyclic tensile strain (1 Hz) at 30% or 60% of the strain at failure, for 0 h (control), 15 min, 30 min, 1 h, or 5 h. Post loading, a quasi-static test to failure assessed damage. Gene expression at a selected loading regime (1 h at 30% failure strain) was analyzed 6 h post loading by quantitative real-time polymerase chain reaction. Compared with unloaded controls, loading at 30% failure strain took 5 h to lead to a significant decrease in failure stress, whereas loading to 60% led to a significant reduction after 15 min. Loading for 1 h at 30% failure strain did not create significant structural damage, but increased Collagen-1-alpha-chain-1 and interleukin-6 ( IL6) expression, suggesting a role of IL6 in tendon adaptation to exercise. Correlating failure properties with fatigue damage provides a method by which changes in gene expression can be associated with different degrees of fatigue damage. [ABSTRACT FROM AUTHOR]

Pre-ascent climbing route visual inspection (route preview) has been suggested as a key climbing performance parameter although its role has never been verified experimentally. We examined the efficacy of this perceptual-cognitive skill on indoor sport climbing performance. Twenty-nine male climbers, divided into intermediate, advanced and expert climbing level groups, climbed two indoor sport routes matching their climbing level and, where applicable, routes below their climbing level. At each level, one route was climbed with a preview, where participants benefited from a 3-min pre-ascent climbing route visual inspection. Performance was assessed in terms of output (route completion) and form (number and duration of moves and stops). Route preview did not influence the output performance. Climbers using visual inspection were no more likely to finish the ascent than those without the option of using visual inspection. Conversely, route preview did influence form performance; climbers made fewer, and shorter stops during their ascent following a preview of the route. Form performances differences remained when baseline ability levels were taken into account, although for shorter duration of stops only with expert climbers benefiting most from route preview. The ability to visually inspect a climb before its ascent may represent an essential component of performance optimization. [ABSTRACT FROM AUTHOR]

To describe prospective associations between ambulatory activity (AA), body composition and muscle function in older adults, 697 community-dwelling participants (49% female; mean age=62 ± 7 years) were assessed for changes in body fat and leg lean mass using dual-energy x-ray absorptiometry, leg strength using dynamometer, and whole body muscle quality (WBMQ; an estimate of specific force) over 2.6 ± 0.4 years. AA was negatively associated with fat mass in both sexes but baseline AA did not predict change in fat mass. Habitual AA was weakly, but significantly, negatively associated with change in total body fat (−0.16 kg/step × 103/day, P=0.011) and trunk fat (−0.12 kg/step × 103/day, P=0.044) in men. Habitual AA was also weakly, but significantly, positively associated with change in leg lean mass in both men and women (both P<0.05), as well as change in leg strength (1.37 kg/step × 103/day, P=0.001) and WBMQ (0.03 kg/kg/step × 103/day, P=0.002) in women only. Partial R2s for these associations were in the range of 1.2-3.2%. Although, these associations are modest, increases in objectively assessed physical activity may represent a target for improving body composition and muscle function in community-dwelling older adults. [ABSTRACT FROM AUTHOR]