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.
"Exercise that exerts in high muscle-contraction or ground-reaction forces on the skeleton, such as resistance training  or structured jump-training, respectively, increase BMD in pre-and post-menopausal women   . Consistent with controlled studies of high-impact exercise and resistance training in women, voluntary long-term participation in running or weightlifting was associated with greater BMD compared with participation in cycling, a weight-supported activity, in adult men  . However, there are very few controlled trials that examine the effects of resistance training or high-impact exercise on bone mass in men        . "
"Studies on male athletic populations have demonstrated that non-weight bearing physical activity can have a negative impact on bone density (Smathers et al., 2009). Low BMD has been observed in both weight and non-weight bearing male athletic populations such jockeys, cyclists and endurance runners (Fredericson et al., 2007; Greene et al., 2013; Nichols & Rauh, 2011; Rector et al., 2008; Smathers et al., 2009) The recommended dietary intakes for calcium focus on maximizing bone mass accretion "
[Show abstract][Hide abstract] 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.
International journal of sport nutrition and exercise metabolism 02/2015; DOI:10.1123/ijsnem.2014-0202 · 2.44 Impact Factor
"Cycling is classed as a nonweight bearing sport (Rector et al. 2008) and cyclists frequently present with lower total and site-specific bone mineral density (BMD) compared with athletes participating in weight-bearing sports (Rector et al. 2008; Stewart and Hannan 2000) or even compared with age-matched sedentary controls (Campion et al. 2010; Medelli et al. 2009b), with a consistent finding of 60% of cyclists tested being classed as osteopenic (Medelli et al. 2009a; Nichols et al. 2003 ; Rector et al. 2008). Moreover, BMD in competitive ( Barry et al. 2011; Guillemant et al. 2004 ; Herrmann et al . "
[Show abstract][Hide abstract] ABSTRACT: Previous studies suggest that seasoned cyclists may incur a low bone mineral density. This study investigated the effect of multiday cycling on bone turnover. Ten male cyclists completed 4 consecutive days of cycling for 3 h·day(-1). Sweat calcium excretion during exercise and serum calcium, cortisol, bone formation marker (bone alkaline phosphotase (bone-ALP)), bone resorptive marker (C-terminal telopeptide of type I collagen (β-CTX)), and parathyroid hormone concentration were measured before and immediately postexercise each day. Serum β-CTX concentration increased from pre- to postcycling on days 1 and 2 (p = 0.01) (day 1: 0.31 ± 0.14 to 0.60 ± 0.4 ng·mL(-1); day 2: 0.58 ± 0.26 to 0.87 ± 0.42 ng·mL(-1)), while serum bone-ALP concentration remained unchanged. Conversely, on days 3 and 4 both serum β-CTX (day 3: 0.60 ± 0.26 to 0.43 ± 0.26 ng·mL(-1), p < 0.05; day 4: 0.63 ± 0.21 to 0.43 ± 0.22 ng·mL(-1), p < 0.001) and bone-ALP (p < 0.01) response to exercise was suppressed. Interestingly, calcium lost to sweat and postexercise serum cortisol concentration were also significantly lower on days 3 and 4 than on day 1 (p < 0.05). However, both serum β-CTX (102%-124%) and bone-ALP (25%-29%) remained persistently elevated after 21 h of overnight recovery on all successive days compared with day 1 pre-exercise, where the percentage increase was greater for β-CTX (p < 0.05). Bone resorption, immediately following prolonged cycling, is acutely reduced by the third and fourth consecutive days and is coincident to reduced sweat calcium excretion and cortisol concentration. However, multiday cycling imposes a persistent increase in bone resorption following overnight recovery.
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