Is there a synergy between physical exercise and drug therapies for osteoporosis?

Combining physical exercise with drug therapies for osteoporosis has been attempted with the aim to maximize osteogenic stimulus. Potential synergetic effects may prevent post-menopausal bone loss, or maximise gains during peak bone mass acquisition. However, research studies yielded mixed results, impeding the emergence of a consensus on the effects of exercise and drug therapies for osteoporosis on bone tissue. Independent, additive or synergetic effects of exercise and drug therapies have been reported, but while animal studies offer promising results, human studies are less clear. The aim of this work was to critically review existing data on the subject in an attempt to clarify existing knowledge and to encourage further investigations with a 2 x 2 factorial design, as elucidation of these questions will benefit osteoporosis prevention.

Relationships between serum leptin and bone markers during stable weight, weight reduction and weight regain in male and female judoists.

OBJECTIVE: Despite a preliminary understanding of leptin-skeletal interactions, data in humans are inconsistent and the exact roles of leptin on bone metabolism have not yet been defined. The aim of this study was to examine the possible role of leptin in the regulation of bone metabolism in healthy, physically trained adults. METHODS AND DESIGN: Body composition and bone mass (dual-energy X-ray absorptiometry), anthropometry, serum leptin, insulin, cortisol, osteocalcin, C-terminal telopeptide of type I collagen (CTx) and total plasma proteins were measured in judoists at normal body weight, after weight reduction and after weight regain. Physical training, weight cycling history, menstrual status and nutritional intake using a 7-day food record were assessed. RESULTS: Precompetitive weight loss averaged 4 +/- 0.3% of bodyweight and resulted in a significant decrease in leptin levels of 64% (P < 0.001) and of 31% for insulin (P < 0.0001). CTx and cortisol concentrations rose by 33% (P < 0.0001) and 81% (P < 0.05) respectively. Osteocalcin and total plasma protein remained unaffected by weight loss. A 4 +/- 0.5% weight regain induced a 276% increase in leptin levels (P < 0.001) and an 18% increase in insulin (P < 0.001). CTx and cortisol decreased by 23% (P < 0.0001) and 27% (P < 0.05) respectively. Changes in leptin were significantly correlated with changes in bone resorption marker in response to both weight loss (r = 0.56, P < 0.01) and regain (r = 0.44, P < 0.05). CONCLUSIONS: These findings suggest that leptin is involved in the regulation of bone metabolism in healthy adults and might play a potential role in the prevention of osteoporosis.

Thicker radial cortex in physically active prepubertal girls compared to controls.

This study was carried out to investigate the effects of physical activity on cortical bone of the radius in a population of prepubertal girls. Forty-nine healthy girls, 17 actives (10.62 +/- 1.56 years) and 32 controls (9.84 +/- 1.23 years) participated in this study. The active group was involved in gymnastics, judo, and dance on average 7.76 +/- 3.94 h/week. Bone mineral content (BMC) and density (BMD) were performed at the distal third of the non-dominant radius using DXA. The lean mass of the non-dominant forearm was derived from the total body analysis performed with DXA. In order to obtain bone cortical thickness, standard radiographs of the non-dominant radius were scanned and computed using a software program based on radiogrammetry. BMD and BMC values were higher in actives than in controls. Cortical thickness at the ulnar side correlated significantly with all the anthropometric and densitometric values as well as the duration of training. In addition, cortical thickness at the ulnar side was significantly higher in the actives compared to the controls. After adjustment for the duration of training per week, cortical thickness of the ulnar side did not differ any more between actives and controls. The same observation was obtained after adjustment for the forearm lean mass. In our active population, physical practice seemed to have induced greater BMC and higher cortical thickness than those observed in the sedentary.

Fractal analysis of bone texture: a screening tool for stress fracture risk?

BACKGROUND: The aim of this study was to identify specific bone characteristics of stress fracture (SF) cases in sportswomen. To date, no tool is able to distinguish individuals who are at risk, limiting preventive measures. MATERIAL AND METHODS: We investigated the skeletal system of sportswomen who did sustain SF in the past (n = 19) and compared it with that of female controls (C) with a similar sporting history but without any fracture history (n = 20). Bone mass and body composition were measured using dual-energy X-ray absorptiometry. Bone micro-architecture was investigated by calcaneal ultrasound and fractal analysis of calcaneus radiographic images. Oestradiol levels were measured by E.I.A, and IGF-1 by R.I.A. Menstrual characteristics, nutrient intake, and training were assessed using questionnaires. RESULTS: The result of the fractal analysis, expressed by the Hmean parameter, was significantly lower in the SF group, reflecting a more complex structure of the trabecular micro-architectural organization (P < 0.005). Body mass index (BMI) at birth was also found to be lower in the SF cases as compared with their C (P < 0.03). Multivariate analysis revealed that the fractal parameter Hmean, bone mineral content (BMC) at Ward's triangle and the BMI at birth correctly assigned 84.85% of the female athletes into their respective SF or C groups (P = 0.001). CONCLUSION: These results suggest that the fractal parameter and the BMI at birth may be able to identify female athletes most at risk for this overuse bone injury, as their low indexes might reflect a greater skeletal sensitivity.