The Relationship between Vitamin D Levels, Injury and Muscle Function in Adolescent Dancers.

Vitamin D has been shown to benefit a diverse range of health functions including muscle function. The aim of the present study was to identify serum 25(OH)D3 levels in a sample of adolescent dancers and compare them to muscle function and injury incidence. We incorporated a cross-sectional design to study 49 pre-professional male and female dancers (17±4.44 yrs, 52.1±6.72 kg, 1.63±0.07 m) in full-time training in Bazil. Serum 25[OH]D3 was analyzed by Enzyme-linked Immunosorbent Assay; quadriceps and hamstring peak torque and muscle fatigue were measured by isokinetic dynamometer at 60 and 300° s-1. Injury type and location in the previous 6-months were determined by self-report questionnaire. Participants were categorized into 2 groups: normal or insufficient/deficient (>or<30 ng/ml 25[OH]D3). Results indicated the normal serum 25[OH]D3 group had significantly lower fatigue rates than the insufficient/deficient group (p<0.05) but not for the other muscle function parameters. Fifty-seven percent of participants reported at least 1 injury. The most common were sprains (33%) and tendinopathies (19%). Injured dancers had significantly lower peak torque at 60°/s. The link between serum 25[OH]D3 and reduced muscle fatigue resistance has not been shown before, though the underlying mechanisms aren't apparent and the link between muscular strength and injury has been previously evidenced.

The impact of obesity in the kinematic parameters of gait in young women.

BACKGROUND: The prevalence of obesity is increasing in the population, particularly in women. Obesity has an impact on the musculoskeletal system, leading to knee and ankle overexertion, difficulty with balance, and functional disability. The aim of this study was to identify changes in kinematic parameters of gait in obese young women. METHODS: A case-control study with 24 obese women (mean age 35.20 ± 9.9 years and mean body mass index of 31.85 ± 2.94 kg/m(2)) and 24 eutrophic women (mean age of 36.33 ± 11.14 and mean body mass index of 21.82 ± 1.58 kg/m(2)). The gait of women was evaluated by the system Vicon Motus® 9.2. The linear parameters of speed, cadence, right and left step, and stride lengths were studied, as well as the angular parameters of knee and ankle. RESULTS: There was a decrease in linear gait parameters (P < 0.001), speed, cadence, right and left step, and stride lengths. In regard to the angular parameters of the knee and ankle, there were also differences between the analyses (P < 0.001). At the knee joint, obese women have delayed onset of the second wave of flexion, exacerbating such movement in order to compensate. In regard to the ankle, both groups showed curves of normal plantar flexion and dorsiflexion, but there was a delay in the path graph in the ankle of obese women indicating a reduced range of motion and possible over-exertion of the pretibial muscles and soleus muscles simultaneously. CONCLUSION: The results of this study revealed that obesity is a factor that negatively influences the kinematic parameters of gait of young women.