Influence of exercise mode and osteogenic index on bone biomarker responses during short-term physical training
ABSTRACT Prescribing exercise based on intensity, frequency, and duration of loading may maximize osteogenic responses in bone, but a model of the osteogenic potential of exercise has not been established in humans. In rodents, an osteogenic index (OI) has been used to predict the osteogenic potential of exercise. The current study sought to determine whether aerobic, resistance, or combined aerobic and resistance exercise programs conducted over eight weeks and compared to a control group could produce changes in biochemical markers of bone turnover indicative of bone formation. We further sought to determine whether an OI could be calculated for each of these programs that would reflect observed biochemical changes. We collected serum biomarkers [bone-specific alkaline phosphatase (BAP), osteocalcin, tartrate-resistant acid phosphatase (TRAP), C-terminal telopeptide fragment of type I collagen (CTx), deoxypyridinoline (DPD), 25-hydroxy vitamin D (25(OH)D), and parathyroid hormone (PTH)] in 56 women (20.3+/-1.8 years) before, during and after eight weeks of training. We also measured bone mineral density (BMD) at regional areas of interest using DXA and pQCT. Biomarkers of bone formation (BAP and osteocalcin) increased in the Resistance and Combined groups (p<0.05), while biomarkers of bone resorption (TRAP and DPD) decreased and increased, respectively, after training (p<0.05) in all groups. Small changes in volumetric and areal BMD (p<0.05) were observed in the distal tibia in the Aerobic and Combined groups, respectively. Mean weekly OIs were 16.0+/-1.9, 20.6+/-2.2, and 36.9+/-5.2 for the Resistance, Aerobic, and Combined groups, respectively. The calculated osteogenic potential of our programs did not correlate with the observed changes in biomarkers of bone turnover. The results of the present study demonstrate that participation in an eight week physical training program that incorporates a resistance component by previously inactive young women results in alterations in biomarkers of bone remodeling indicative of increased formation without substantial alterations in markers of resorption.
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ABSTRACT: Although combination of physical activity with supplementation has being investigated on its effects in maintaining and enhancing bone health, muscular strength and immune functions, little is known about the effectiveness of combined Eurycoma longifolia Jack supplementation and a circuit training programme on bone metabolism markers, muscular strength and power, and immune functions in adult men. This study investigated the combined effects of 8 weeks Eurycoma longifolia Jack supplementation and circuit training programme on bone metabolism markers, isokinetic muscular strength and power, and immune functions in adult men. Forty adult male subjects (mean age:46.8±5.5 years), were age-matched and subsequently assigned into four groups with n=10 per group: Control group with placebo supplementation (C), Eurycoma longifolia Jack supplementation group (ElJ), circuit training programme group with placebo (Ex), and combined circuit training programme with Eurycoma longifolia Jack group (ElJEx). Circuit training programme consisted of 2 circuits of exercise, with 10 different exercise stations per circuit, three times per week for a total of 8 weeks. Subjects in C and Ex group consumed placebo, subjects in ElJ and ElJEx groups consumed Eurycoma longifolia Jack, 7 days/week for 8 weeks. Before and after 8 weeks of experimental period, subjects’ anthropometry, isokinetic muscular strength and power were measured. Blood samples were taken to determine bone metabolism markers and immune functions. ElJEx increased knee extension peak torque at 60o.s-1, shoulder flexion average power at 300o.s-1 and shoulder extension average power at 300o.s-1. Meanwhile, Ex alone could only increase shoulder extension average power at 300o.s-1. These results suggested that combination of circuit training with Eurycoma longifolia Jack (ElJEx) elicited more beneficial effect on isokinetic muscular strength and power than circuit training alone (Ex). Regarding bone metabolism markers and immune function parameters, ElJEx, Ex and ElJ did not elicit any effect on these measured parameters after 8 weeks of experimental period. Combined Eurycoma longifolia Jack supplementation with circuit training programme has potential to be proposed for formulating guidelines in planning exercise and nutritional promotion programmes for the enhancement of muscular strength and power in adult men.
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ABSTRACT: Calcium and vitamin D are essential nutrients for bone health. Periods of activity with repetitive mechanical loading, such as military training, may result in increases in parathyroid hormone (PTH), a key regulator of Ca metabolism, and may be linked to the development of stress fractures. Previous studies indicate that consumption of a Ca and vitamin D supplement may reduce stress fracture risk in female military personnel during initial military training, but circulating markers of Ca and bone metabolism and measures of bone density and strength have not been determined. This randomized, double-blind, placebo-controlled trial sought to determine the effects of providing supplemental Ca and vitamin D (Ca+Vit D, 2000mg and 1000IU/d, respectively), delivered as 2 snack bars per day throughout 9weeks of Army initial military training (or basic combat training, BCT) on PTH, vitamin D status, and measures of bone density and strength in personnel undergoing BCT, as well as independent effects of BCT on bone parameters. A total of 156 men and 87 women enrolled in Army BCT (Fort Sill, OK; 34.7°N latitude) volunteered for this study. Anthropometric, biochemical, and dietary intake data were collected pre- and post-BCT. In addition, peripheral quantitative computed tomography was utilized to assess tibia bone density and strength in a subset of volunteers (n=46). Consumption of supplemental Ca+Vit D increased circulating ionized Ca (group-by-time, P=0.022), maintained PTH (group-by-time, P=0.032), and increased the osteoprotegerin:RANKL ratio (group-by-time, P=0.006). Consistent with the biochemical markers, Ca+Vit D improved vBMD (group-by-time, P=0.024) at the 4% site and cortical BMC (group-by-time, P=0.028) and thickness (group-by-time, P=0.013) at the 14% site compared to placebo. These data demonstrate the benefit of supplemental Ca and vitamin D for maintaining bone health during periods of elevated bone turnover, such as initial military training. This trial was registered with ClincialTrials.gov, NCT01617109.Bone 08/2014; 68. DOI:10.1016/j.bone.2014.08.002 · 4.46 Impact Factor
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ABSTRACT: The primary purpose was to identify the relationship between muscle cross sectional area (mCSA), echo intensity (EI), and body composition of Division I cross-country runners. The secondary purpose was to examine differences in these variables in athletes stratified based on stress fracture (SFx) history. Thirty-six athletes were stratified based on sex and previous SFx history. A panoramic scan vastus lateralis (VL) was performed using a GE logiq-e B-mode ultrasound (US). Echo intensity and mCSA were determined from the scan by using a grayscale imaging software (Image-J). Body composition measures were determined using dual-energy x-ray absorptiometry (DEXA). For females, mCSA was significantly correlated with left leg lean mass (LM; R=0.54) and EI (R= -0.57). Lean mass was significantly correlated with bone mineral density (BMD; R=0.58) and content (BMC; R=0.56), while BMC was also correlated with leg LM (R=0.72). For males, mCSA was significantly correlated with leg LM (R=0.66), BMD (R=0.50), and BMC (R=0.54). Leg LM was significantly correlated with BMD (R=0.53) and BMC (R=0.77). Personal best times for males were significantly correlated with FM (R=0.489) and %fat (R=0.556) for the 10 kilometer and 5 kilometer races, respectively. Female and male athletes with previous history of SFx were not significantly different across any variables when compared to athletes with no previous history. These correlations suggest more muscle mass may associate with higher BMD and BMC for stronger bone structure. Modifications in training strategies to include heavy resistance training and plyometrics may be advantageous for preventing risk factors associated with stress fracture reoccurrence.