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: The aim of this study was to examine and compare the effects of different resistance training protocols on bone marker concentrations in older men. Thirty-seven healthy older male subjects were assigned to one of three groups: high-intensity resistance training (HI-RT, age = 57.5 ± 0.8); low-intensity resistance training with vascular restriction (LI-VRT, age = 59.9 ± 1.0); and control (CON, age = 57.0 ± 1.1). Blood samples were collected before and after 6 weeks of resistance training to measure the changes in bone formation [bone alkaline phosphatase, (Bone ALP)] and resorption (C-terminal cross-linking telopeptide of Type-I collagen, CTX) marker concentrations. A significant main effect for time was detected in Bone ALP to CTX ratio for the exercise groups (p < 0.05). There was a significant group effect for percentage changes in serum Bone ALP (21% for LI-VRT, 23% for HI-RT, and 4.7% for CON) and post hoc analysis identified significant increases in serum Bone ALP concentrations in LI-VRT (p = 0.03) and HI-RT (p = 0.02) when compared with CON. The exercise groups had significantly (p < 0.01) greater strength increases in all upper body and leg exercises compared with CON with no significant differences between the exercise groups except for leg extension strength (HI-RT > LI-VRT, p < 0.05). Serum concentrations of Bone ALP and Bone ALP to CTX ratio improved in both resistance training protocols, suggesting increased bone turnover with a balance favoring bone formation. Therefore, despite using low mechanical load, LI-VRT is a potentially effective training alternative to traditional HI-RT for enhancing bone health in older men.Arbeitsphysiologie 08/2011; 111(8):1659-67. DOI:10.1007/s00421-010-1796-9 · 2.30 Impact Factor
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ABSTRACT: This study was designed as a proof-of-concept study to assess the osteogenic index (OI) and changes in bone markers during an 8-wk jump training program. On the basis of the OI, jumps were completed in one or two daily sessions with total jumps per day being equal. Seven males served as controls and participated in their normal strength training program. Fourteen males were divided into two groups, jumping once daily (J1x) or jumping twice daily (J2x), with a 6-h recovery period between sessions (J2x only). Jumping-type exercises were performed on a Plyo Press and started at 20 plyo-jumps per day, three times per week and progressed to 60 plyo-jumps per day, three times per week for the last 3 wk. Blood samples were collected at baseline and at 4 and 8 wk to determine serum concentrations of bone-specific alkaline phosphate and C-terminal telopeptides of type I collagen. OI for each session and week were different (P < 0.05) between the two jumping groups (baseline OI per week, J1x = 28 +/- 0.9, J2x = 34 +/- 0.9). There was a significant change (P = 0.005) in bone-specific alkaline phosphate over time, with 8-wk values being significantly higher than baseline values (change from baseline: J1x = 2.7 +/- 1.4 microg.L-1, J2x = 3.5 +/- 1.3 microg.L-1). J2x had an overall mean change significantly different from zero. C-terminal telopeptides of type I collagen did not change significantly during the 8 wk. The data demonstrate that the bone of young adult males does respond to a high-impact exercise. In addition, compared with completing all plyo-jumps in one session, the use of recovery periods between exercise sessions on the same day may result in positive changes in bone turnover, indicative of an osteogenic effect. The beneficial impact of the OI and how it can be used to design programs to influence bone turnover still remain to be determined.Medicine and science in sports and exercise 02/2010; 42(8):1485-92. DOI:10.1249/MSS.0b013e3181d0fa7a · 4.46 Impact Factor
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ABSTRACT: Cardiovascular disease (CVD) mortality rates are greatly elevated in chronic kidney disease patients receiving maintenance haemodialysis therapy. The purpose of this study was to evaluate the efficacy of intradialytic endurance exercise training on novel risk factors that may contribute to this excessive CVD risk. Seventeen haemodialysis patients were randomized to either an intradialytic exercise training (cycling) group (EX; n = 8) or a non-exercising control group (CON; n = 9) for 4 months. At baseline and following the intervention, we measured serum parameters related to CVD risk and renal function, used echocardiography to measure variables related to cardiac structure and function and assessed physical performance by a validated shuttle walk test. Performance on the shuttle walk test increased by 17% in EX (P < 0.05), but did not change in CON. There was no change in serum lipids or inflammatory markers (C-reactive protein, interleukin-6) in either group. Serum thiobarbituric acid reactive substances, a marker of oxidative stress, were reduced by 38% in EX (P < 0.05), but did not change in CON. In addition, serum alkaline phosphatase (ALP), a putative risk factor for vascular calcification, was reduced by 27% in EX (P < 0.05), but did not change in CON. There was no change in left atrial volume, left ventricular mass or myocardial performance index in either group. However, the thickness of the epicardial fat layer was reduced by 11% in EX (P < 0.05), but did not change in CON. Furthermore, the change in physical performance was inversely correlated to the change in epicardial fat (r = -0.63; P = 0.03). These results suggest that endurance exercise training may improve CVD risk in haemodialysis patients by decreasing novel risk factors including serum oxidative stress, ALP and epicardial fat.Nephrology Dialysis Transplantation 02/2010; 25(8):2695-701. DOI:10.1093/ndt/gfq106 · 3.49 Impact Factor