Participation in road cycling vs running is associated with lower bone mineral density in men
ABSTRACT The effects of regular non-weight-bearing (NWB) exercise on bone health are largely unknown. The objective of the study was to determine the effects of participation in NWB sports on bone health in adult male recreational athletes. Male cyclists (NWB; n = 27) and runners (weight-bearing [WB]; n = 16) aged 20 to 59 years were recruited from the community. Whole-body and regional bone mineral content and bone mineral density (BMD), and body composition were assessed using dual x-ray absorptiometry. Bone formation and resorption markers, and hormones were measured in serum. Bone-loading history was estimated from a sports participation history questionnaire. Nutrient intake and current physical activity were estimated from 7-day written logs. The NWB athletes had significantly lower BMD of the whole body and spine than the WB athletes, despite having similar age, weight, body mass index, body composition, hormonal status, current activity level, and nutrient intakes. Sixty-three percent of NWB athletes had osteopenia of the spine or hip, compared with 19% of WB athletes. Cyclists were 7 times more likely to have osteopenia of the spine than runners, controlling for age, body weight, and bone-loading history. There were no group differences in serum markers of bone turnover. Based on the results of this study, current bone loading is an important determinant of whole-body and lumbar spine BMD. Therefore, bone-loading activity should be sustained during adulthood to maintain bone mass.
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ABSTRACT: Some athletes avoid dairy in the meal consumed before exercise due to fears about gastrointestinal discomfort. Regular exclusion of dairy foods may unnecessarily reduce intake of high quality proteins and calcium with possible implications for body composition and bone health. This study compared the effects of meals that included (Dairy) or excluded (Control) dairy foods on gastric comfort and subsequent cycling performance. Well-trained female cyclists (n=32; mean ± SD; 24.3 ± 4.1 y; VO2peak 57.1 ± 4.9 ml/kg/min) completed two trials (randomised cross-over design) in which they consumed a meal (2 g/kg carbohydrate and 54 kJ/kg) 2 h prior to a 90 min cycle session (80 min at 60% maximal aerobic power followed by a 10 min time trial; TT). The Dairy meal contained 3 serves of dairy foods providing ~1350 mg calcium. Gut comfort and palatability were measured using questionnaires. Performance was measured as maximum mean power during the TT (MMP10min). There was no statistical or clinical evidence of an effect of meal type on MMP10min with a mean difference (Dairy - Control) of 4 W (95% CI [-2, 9]). There was no evidence of an association between pre-trial gut comfort and meal type (p=0.15) and between gut comfort Δ scores and meal type post-meal (p=0.31), pre-exercise (p=0.17) or post-exercise (p=0.80). There was no statistical or clinical evidence of a difference in palatability between meal types. In summary, substantial amounts of dairy foods can be included in meals consumed prior to strenuous cycling without impairing either gut comfort or performance.International journal of sport nutrition and exercise metabolism 07/2014; 24(5). DOI:10.1123/ijsnem.2014-0069 · 1.98 Impact Factor
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ABSTRACT: Abstract Mountain biking (MB), unlike road cycling (RC) involves exposure to ground impact bone strain and requires upper-body muscle forces to maintain stability over uneven terrain and therefore may have differential effects on radial bone structure and strength. This study aimed to compare serum bone turnover marker concentration, 1-repetition maximum muscle strength and the radial proximal (diaphysis) and distal (metaphysis) bone structure [bone mineral content, total and cortical area (CoA), density and thickness, diameter and circumference], strength strain indices and muscle cross-sectional area (MCSA) using peripheral quantitative computed tomography (pQCT) between 30 male cyclists (18-34 years) MB (n = 10), RC (n = 10) and non-athletes controls (CON, n = 10). Differences were assessed by ANOVA and an ANCOVA (adjusting for body mass and height) where appropriate. MB radii were characterised by significantly stronger (14-16%), denser (9-27%) and larger (10%) metaphyses and stronger (22-23%) and larger (11-13%) diaphyses compared to RC and CON. RC had significantly 7% higher strength indices and 4% greater CoA and thickness than CON at the diaphysis, with no differences for other bone measurements. Serum C-terminal telopeptides of type-1 collagen concentration (bone resorption marker) was higher in RC than MB (p < 0.05) and above the age-reference range. MCSA and strength were greater in MB than RC (p < 0.05). Muscle forces generated during RC appear to produce an osteogenic stimulus to increase radial bone strength indices with minimal improvement in bone structure. However greater resorptive activity in RC suggests inadequate loading to support bone maintenance. In conclusion, bone loading, muscle size and strength of MB are superior to RC.European Journal of Sport Science 07/2014; DOI:10.1080/17461391.2014.933881 · 1.31 Impact Factor
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ABSTRACT: Research examining the preventative effects of calcium and vitamin D supplementation has focused on children and females, leaving the effects on male bone mineral density (BMD) largely unexplored. Thus, the aim of this systematic review and meta-analysis is to examine the efficacy of calcium supplementation, with or without vitamin D for improving BMD in healthy males. Medline, EMBASE, SPORTDiscus, Academic Search Complete, CINHAHL Plus and PubMed databases were searched for studies including healthy males which provided participants calcium supplementation with or without vitamin D and used changes to BMD as the primary outcome measure. Between trial standardised mean differences of percentage change from baseline in BMD of femoral neck, lumbar spine, total body and total hip sites were calculated. Nine studies were included in the systematic review with six references totaling 867 participants contributing to the meta-analysis. Significant pooled effects size (ES) for comparison between supplementation and control groups were found at all sites included in the meta-analysis. The largest effect was found in total body (ES=0.644; 95% CI=0.406 to 0.883; p=0.000), followed by total hip (ES=0.483, 95% CI= 0.255 to 0.711, p=0.000), femoral neck (ES=0.402, 95% CI=0.233 to 0.570, p=0.000) and lumbar spine (ES=0.306, 95% CI=0.173 to 0.440,p=0.000). Limited evidence appears to support the use of calcium and vitamin D supplementation for improving BMD in older males. There is a need for high quality randomised controlled trials, especially in younger and middle-aged male cohorts and athletic populations to determine whether supplementation provides a preventative benefit.