Changes in performance, energetics and kinematics during age-group swimmers off-season inform the prescription of training for the following season. Age-group swimmers (n = 15, age 14.3 ± 0.7 years) of equal maturational stage performed a 400-m front crawl (T400) before and after a four-weeks training cessation period. Performance-related energetic and kinematic variables were obtained controlling for anthropometric changes and non-swimming specific physical activities during off-season. T400 time decreased 3.8% (95%CI 1.4 to 6.1%; p < 0.01; d = 0.90) with non-specific physical activities (1814 ± 1989 MET-min•wk −1) accounting for~40% of the underlying variance (p = 0.01; η 2 = 0.40). Stroke rate and stroke index decreased despite similar stroke length and index of coordination values. Although mean response time, amplitude, maximal oxygen uptake, heart rate, total energy expenditure, metabolic power and energy cost were similar, aerobic contribution decreased by~1.8% (−2.7 to −0.9%; p < 0.01; d = −1.19) and anaerobic lactic contribution increased by~1.6% (0.8 to 2.5%; p < 0.01; d = 1.08) over the off-season. Impaired performance was mainly associated with a decreased stroke rate (r = −0.85 to −0.61; p ≤ 0.02), increased peak blood lactate (r = −0.52; p = 0.05) and fewer non-swimming specific physical activities performed during the offseason (r = −0.58; p = 0.03). The end-of-season cessation of training yielded moderate impairments in agegroup swimmers performance-related energetic and kinematic factors, however non-specific physical activities can minimise fitness losses.
Osteoporosis is characterized by bone loss. The present study aims to investigate the effects of bovine colostrum (BC) on bone metabolism using ovariectomized (OVX) and orchidectomized (ORX) rat models. Twenty-seven-week-old Wistar Han rats were randomly assigned as: (1) placebo control, (2) BC supplementation dose 1 (BC1: 0.5 g/day/OVX, 1 g/day/ORX), (3) BC supplementation dose 2 (BC2: 1 g/day/OVX, 1.5 g/day/ORX) and (4) BC supplementation dose 3 (BC3: 1.5 g/day/OVX, 2 g/day/ORX). Bone microarchitecture, strength, gene expression of VEGFA, FGF2, RANKL, RANK and OPG, and bone resorption/formation markers were assessed after four months of BC supplementation. Compared to the placebo, OVX rats in the BC1 group exhibited significantly higher cortical bone mineral content and trabecular bone mineral content (p < 0.01), while OVX rats in the BC3 group showed significantly higher trabecular bone mineral content (p < 0.05). ORX rats receiving BC dose 2 demonstrated significantly higher levels of trabecular bone mineral content (p < 0.05). Serum osteocalcin in the ORX was pointedly higher in all BC supplementation groups than the placebo (BC1: p < 0.05; BC2, BC3: p < 0.001). Higher doses of BC induced significantly higher relative mRNA expression of OPG, VEGFA, FGF2 and RANKL (p < 0.05). BC supplementation improves bone metabolism of OVX and ORX rats, which might be associated with the activation of the VEGFA, FGF2 and RANKL/RANK/OPG pathways.
Given the lack of relevant data, the aim of this study was to examine femur cortical and trabecular bone in female and male professional ballet dancers. 40 professional ballet dancers and 40 sex- and age-matched non-exercising controls volunteered. Femoral bone density was scanned by dual-energy X-ray absorptiometry (DXA) scan. A 3D-DXA software was used to analyse trabecular and cortical bone. Anthropometry, maturation (Tanner staging), menstrual parameters (age at menarche and primary amenorrhea), energy availability and nutritional analysis (3-day record) were also assessed.Compared to non-exercising participants, dancers exhibited significantly higher volumetric density for integral, cortical and trabecular bone, and thicker cortex at the femur. Ballet dancers demonstrated lower body weight compared to controls (p < 0.01). Female dancers had their menarche later than controls, and the prevalence of primary amenorrhea were significantly higher in dancers than controls (p < 0.01). Dancer's energy availability was below the normal range (<30 kcal/kgFFM/day). Despite the presence of certain osteoporosis risk factors such as low energy availability, primary amenorrhoea and lower body weight, professional ballet dancers revealed higher bone density for both cortical and trabecular bone compartments compared to controls.
Purpose To determine whether risk factors normally associated with low bone mass in athletic populations (i.e. nutrition intake, energy expenditure and energy availability) are significant predictors of bone mass changes in vocational dance students. MethodsThe total of 101 vocational dancers (63 females, 12.8±2.2yrs; 38 males, 12.7±2.2yrs) and 118 age-matched controls (50 females, 13.0±2.1yrs; 68 males, 13.0±1.8yrs) were monitored for three consecutive years. Bone mass parameters were measured annually at impact sites (femoral neck -FN; lumber spine -LS) and nonimpact site (forearm) using DXA. Nutrition (3-day record), energy expenditure (accelerometer), energy availability and IGF-1 serum concentration (immunoradiometric assays) were also assessed. ResultsFemale and male vocational dancers had consistently reduced bone mass at all anatomical sites (p<0.001) than controls. IGF-1 did not differ between male vocational dancers and controls, but female dancers showed it higher than controls. At baseline, calcium intake was significantly greater in female vocational dancers than controls (p<0.05). Male vocational dancers' fat and carbohydrate intakes were significantly lower than matched controls (p<0.001 and p<0.05, respectively). Energy availability of both female and male vocational dancers was within the normal range.A significant group effect was found at the FN regarding energy intake (p<0.05) in female dancers. No significant predictors were found to explain bone mass differences in males. ConclusionOur 3-years study revealed that both female and male vocational dancers displayed lower bone mass compared to controls, at both impact and non-impact sites.The aetiology of these findings may be grounded on factors different than those usually considered in athletic populations.
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