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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]

Aim This study aims to describe the lifetime picture of vitamin D deficiency, as measured by serum 25( OH) D concentration, in Tasmania (latitude 43° S). Methods Five cross-sectional studies were used: a sample of primary schoolchildren ( n = 201, aged 7-8 years), two samples of adolescents (sample 1: n = 374, aged 15-18 years; sample 2: n = 136, aged 16-19 years), a sample of young to middle-aged adults ( n = 262, aged 19-59 years) and a sample of older adults ( n = 1092, aged 50-80 years). Results In winter/spring, approximately two-thirds of the adolescents and adults (young, middle-aged and older) had 25( OH) D levels ≤50 nmol/ L, and around 10% had 25( OH) D levels ≤25 nmol/L. The prevalence of vitamin D deficiency was much lower for primary schoolchildren (11.5% < 50 nmol/ L, 0.5% ≤ 25 nmol/ L). In summer/autumn, approximately one-third of the adolescents and adults had 25( OH) D levels ≤50 nmol/ L, and very few had 25( OH) D levels ≤25 nmol/L. For the adolescents and adults, even among those who reported the highest category of sun exposure, approximately 45% had 25( OH) D levels ≤50 nmol/ L in winter/spring. Conclusions Vitamin D deficiency was uncommon among our sample of primary school children but increased substantially during the teenage years and seemed to remain high throughout the rest of life, suggesting that mild vitamin D deficiency is endemic in Tasmania apart from in the very young. [ABSTRACT FROM AUTHOR]

Background: There is controversy about whether pain and radiographic osteoarthritis (ROA) predict subsequent cartilage loss. The aim of this study was to describe the relationship between ROA, pain and cartilage loss in the knee. Methods: We studied randomly selected subjects at baseline and approximately 2.9 years later ( n= 399). The presence of ROA was assessed at baseline with a standing anteroposterior semiflexed radiograph scored using the Osteoarthritis Research Society International atlas for osteophytes (OP) and joint space narrowing (JSN). Pain was assessed by the Western Ontario McMaster Osteoarthritis Index. Subjects' medial and lateral tibial cartilage volumes were determined by magnetic resonance imaging at both time points. Results: In cross-sectional analysis, both medial and lateral tibial cartilage volumes were lower in those with ROA. Any medial ROA predicted medial tibial cartilage loss (3.2% (standard deviation (SD) 5.6) vs 1.9% (SD 5.3) per annum) while any lateral ROA predicted both medial (4.0% (SD 6.0) vs 2.2% (SD 5.3) per annum) and lateral (3.5% (SD 5.8) vs 1.6% (SD 4.2) per annum) tibial cartilage loss (all P < 0.05). In multivariate analysis, JSN and OP at both medial and lateral sites had independent dose-response associations with tibial cartilage loss at both sites. Pain was an independent predictor of lateral, but not medial, tibial cartilage loss after taking ROA into account. Conclusions: Subjects with ROA (either JSN or OP) and, to a lesser extent, pain lose cartilage faster than subjects without ROA and the more severe the ROA the greater the rate of loss. These findings have implications for the design of clinical trials. [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]