Comparative effects of various running exercise modalities on femoral bone quality in rats

BACKGROUND

It is now well established that physical exercise is an effective preventive method to reduce and treat certain chronic diseases, particularly musculoskeletal disorders. At the bone level, running exercise is well known for its positive effects on various parameters of bone quality. There is, however, no consensus regarding the effects of different running exercise modalities on bone quality.

AIM

The objective of this study was to compare the effects of three treadmill running modalities: intermittent, moderate continuous, and a combination of both-on bone quality parameters in rats.

METHODS

Thirty-nine, 5-week-old, male Wistar rats were randomly divided in 4 groups: sedentary control (SED; n = 10), intermittent running exercise (IE; n = 10), continuous running exercise (CE; n = 10) and combined running exercise (COME; n = 9). Rats in running groups were exercised 45 min/day, 5 days/week, for 8 consecutive weeks. Femoral micro-architectural parameters were assessed by micro-CT; femoral osteocyte apoptosis, osteoclast resorption and bone histomorphometry were assessed by histology.

RESULTS

Femoral trabecular thickness in the combined running group was increased (p < 0.0001) compared to respective results in the other running groups (0.13 mm vs 0.11 mm). The cortical thickness, osteocyte lacunae occupancy rate in the whole femur, numbers of apoptotic osteocytes and osteoclastic resorption surfaces were not significantly different between groups. Statistical differences were occasionally noted depending on the femoral anatomical region.

CONCLUSION

These results suggest that the femur should not be considered as the better bone to study the effects of running protocols.

Physical Activity and Bone Vascularization: A Way to Explore in Bone Repair Context?

Physical activity is widely recognized as a biotherapy by WHO in the fight and prevention of bone diseases such as osteoporosis. It reduces the risk of disabling fractures associated with many comorbidities, and whose repair is a major public health and economic issue. Bone tissue is a dynamic supportive tissue that reshapes itself according to the mechanical stresses to which it is exposed. Physical exercise is recognized as a key factor for bone health. However, the effects of exercise on bone quality depend on exercise protocols, duration, intensity, and frequency. Today, the effects of different exercise modalities on capillary bone vascularization, bone blood flow, and bone angiogenesis remain poorly understood and unclear. As vascularization is an integral part of bone repair process, the analysis of the preventive and/or curative effects of physical exercise is currently very undeveloped. Angiogenesis–osteogenesis coupling may constitute a new way for understanding the role of physical activity, especially in fracturing or in the integration of bone biomaterials. Thus, this review aimed to clarify the link between physical activities, vascularization, and bone repair.

The Specificities of Elite Female Athletes: A Multidisciplinary Approach

Female athletes have garnered considerable attention in the last few years as more and more women participate in sports events. However, despite the well-known repercussions of female sex hormones, few studies have investigated the specificities of elite female athletes. In this review, we present the current but still limited data on how normal menstrual phases, altered menstrual phases, and hormonal contraception affect both physical and cognitive performances in these elite athletes. To examine the implicated mechanisms, as well as the potential performances and health risks in this population, we then take a broader multidisciplinary approach and report on the causal/reciprocal relationships between hormonal status and mental and physical health in young (18-40 years) healthy females, both trained and untrained. We thus cover the research on both physiological and psychological variables, as well as on the Athlete Biological Passport used for anti-doping purposes. We consider the fairly frequent discrepancies and summarize the current knowledge in this new field of interest. Last, we conclude with some practical guidelines for eliciting improvements in physical and cognitive performance while minimizing the health risks for female athletes.

Quick benefits of interval training versus continuous training on bone: a dual-energy X-ray absorptiometry comparative study

To delay age-related bone loss, physical activity is recommended during growth. However, it is unknown whether interval training is more efficient than continuous training to increase bone mass both quickly and to a greater extent. The aim of this study was to compare the effects of a 10-week interval training regime with a 14-week continuous training regime on bone mineral density (BMD). Forty-four male Wistar rats (8 weeks old) were separated into four groups: control for 10 weeks (C10), control for 14 weeks (C14), moderate interval training for 10 weeks (IT) and moderate continuous training for 14 weeks (CT). Rats were exercised 1 h/day, 5 day/week. Body composition and BMD of the whole body and femur respectively were assessed by dual-energy X-ray absorptiometry at baseline and after training to determine raw gain and weight-normalized BMD gain. Both trained groups had lower weight and fat mass gain when compared to controls. Both trained groups gained more BMD compared to controls when normalized to body weight. Using a 30% shorter training period, the IT group showed more than 20% higher whole body and femur BMD gains compared to the CT. Our data suggest that moderate IT was able to produce faster bone adaptations than moderate CT.

Oral contraceptive use and saliva diurnal pattern of metabolic steroid hormones in young healthy women

BACKGROUND

The impact of oral contraceptives (OCs) on the saliva diurnal pattern of metabolic steroid hormones remained unknown.

STUDY DESIGN

Saliva samples were taken from young healthy women (11 OC users, 10 non-OC users) to analyze cortisol, dehydroepiandrosterone (DHEA) and testosterone 4 times (days 1, 8, 15 and 22) over one menstrual cycle.

RESULTS

OC use decreased saliva testosterone concentrations (p<.01) under all conditions of day and time, but not saliva cortisol. OC also decreased saliva DHEA concentrations during the first part of the day (p<.05), with a dampened amplitude in its diurnal pattern.

CONCLUSION

The clinical relevance requires further study.

Effect of the alcohol consumption on osteocyte cell processes: a molecular imaging study

We have previously shown microarchitectural tissue changes with cellular modifications in osteocytes following high chronic alcohol dose. The aim of this study was to assess the dose effect of alcohol consumption on the cytoskeleton activity, the cellular lipid content and modulation of differentiation and apoptosis in osteocyte. Male Wistar rats were divided into three groups: Control (C), Alcohol 25% v/v (A25) or Alcohol 35% v/v (A35) for 17 weeks. Bone mineral density (BMD) was assessed by DXA, osteocyte empty lacunae, lacunae surface, bone marrow fat with bright field microscopy. Osteocyte lipid content was analysed with transmission electron microscopy (TEM) and epifluorescence microscopy. Osteocyte apoptosis was analysed with immunolabelling and TEM. Osteocyte differentiation and cytoskeleton activity were analysed with immunolabelling and real time quantitative PCR. At the end of the protocol, BMD was lower in A25 and A35 compared with C, while the bone marrow lipid content was increased in these groups. More empty osteocyte lacunae and osteocyte containing lipid droplets in A35 were found compared with C and A25. Cleaved caspase-3 staining and chromatin condensation were increased in A25 and A35 versus C. Cleaved caspase-3 was increased in A35 versus A25. CD44 and phosphopaxillin stainings were higher in A35 compared with C and A25. Paxillin mRNA expression was higher in A35 versus A25 and C and sclerostin mRNA expression was higher in A35 versus C. We only observed a dose effect of alcohol consumption on cleaved caspase-3 osteocyte immunostaining levels and on the number of lipid droplets in the bone marrow.

Chronic and intermittent exposure to alcohol vapors: a new model of alcohol-induced osteopenia in the rat

BACKGROUND

Different models are used to study the effects of chronic alcohol consumption on bone tissue in the rat. However, the current models take several months to show indices of osteopenia as observed in chronic drinkers. Numerous studies have supported that chronic and intermittent exposure to ethanol vapors has predictive validity as a model of alcohol dependence in humans. However, this model has never been applied to bone research to study its effects on the parameters that define osteopenia. This was the goal of this study in the rat.

METHODS

Male Wistar rats were exposed to ethanol vapor inhalation (n = 6) or air (controls, n = 6). Animals were exposed to chronic (11 weeks) and intermittent (14 hours a day) ethanol vapor reaching stable blood alcohol levels (BALs; 150 to 250 mg/dl) at the end of the third week of inhalation. After the sacrifice, right and left femur and tibia were dissected free of fat and connective tissue and bone mineral density (BMD) was assessed by dual X-ray absorptiometry. The microarchitecture of the femur was studied using microcomputed tomography.

RESULTS

The BMD of the left and right femurs and the left tibia was lower in the ethanol group compared with the control group. The bone volume fraction (BV/TV) and the bone surface density (BS/TV) were lower in the ethanol group compared with control animals. The trabecular number (Tb.N) was lower in the ethanol group while the trabecular spacing was higher.

CONCLUSIONS

The decrease in the BMD, BV/TV, and Tb.N is in the same range as what is observed in human drinkers and what is reported with other animal alcohol models (Lieber-DeCarli liquid diet, ethanol in the tap water). Therefore, this model could be useful to study the effects of chronic alcohol consumption in the bone research field and has the advantage of controlling easily targeted BALs.

Osteocyte apoptosis and lipid infiltration as mechanisms of alcohol-induced bone loss

AIMS

We carried out an in vivo study to assess the relationship between increase in adiposity in the marrow and osteocyte apoptosis in the case of alcohol-induced bone loss.

METHODS AND RESULTS

After alcohol treatment, the number of apoptotic osteocytes was increased and lipid droplets were accumulated within the osteocytes, the bone marrow and the cortical bone micro-vessels. At last, we found an inverse correlation between bone mineral density and osteocyte apoptosis and strong significant correlations between the osteocyte apoptotic number and lipid droplet accumulation in osteocyte and bone micro-vessels.

CONCLUSION

These data show that alcohol-induced bone loss is associated with osteocyte apoptosis and lipid accumulation in the bone tissue. This lipid intoxication, or 'bone steatosis', is correlated with lipid accumulation in bone marrow and blood micro-vessels.

Cortical bone is more sensitive to alcohol dose effects than trabecular bone in the rat

OBJECTIVE

While chronic alcohol consumption is known to decrease bone mineral content (BMC), bone mineral density (BMD), and negatively modify trabecular bone microarchitecture, the impact of alcohol on cortical microarchitecture is still unclear. The aim of this study was to investigate the effects of various doses of alcohol on bone density, trabecular and cortical parameters and bone strength in rats.

METHODS

Forty-eight male Wistar rats were divided into four groups: control (C), alcohol 25% v/v (A25), alcohol 30% v/v (A30) and alcohol 35% v/v (A35). Rats in the alcohol groups were fed a solution composed of ethanol and water for 17 weeks while the control group drank only water. Bone quality and quantity were evaluated through the analysis of density, trabecular and cortical bone microarchitectural parameters, osteocalcin and N-Telopeptide concentrations and a 3-point bending test.

RESULTS

Bone density along with trabecular and cortical thickness were lower in alcohol groups compared to C. BMD was lower in A35 vs. A30 and cortical thickness was lower in A35 vs. A25 and A30. Pore number was increased by alcohol and the porosity was greater in A35 compared to C. N-Telopeptide concentration was decreased in alcohol groups compared to control whereas no differences were observed in osteocalcin concentrations. Maximal energy to failure was lower in A25 and A35 compared to C.

CONCLUSION

Chronic ethanol consumption increases cortical bone damage in rats and may have detrimental effects on bone strength. These effects were dose-dependent, with greater negative effects proportionate to greater alcohol doses.

Osteocalcin-insulin relationship in obese children: a role for the skeleton in energy metabolism

OBJECTIVE

Osteocalcin is a bone-specific protein secreted by osteoblasts and often used as a bone formation biomarker. Rodent studies have reported a hormonal role of osteocalcin on glucose metabolism, increasing insulin secretion and sensitivity and increasing energy expenditure. However, it is unknown whether osteocalcin fulfils the same function in humans.

METHODS

We investigated the relationship between serum osteocalcin and insulin concentrations in 27 prepubertal obese children (9-12 years old) randomly divided into two groups, one of which entered a physical training programme, and 16 nonobese control children. Whole body bone mineral density (WB-BMD), serum osteocalcin, circulating insulin and adiponectin were measured at baseline and after 6 months.

RESULTS

Trained and untrained obese children had higher WB-BMD than controls at baseline. Trained children also displayed a significant insulin increase and a significant adiponectin decrease while osteocalcin was increased compared to untrained obese children. Significant linear correlations between WB-BMD and adiponectin, delta BMD (variation between baseline and after-training values) and delta adiponectin, insulin and osteocalcin, delta insulin and delta osteocalcin, delta insulin and delta under-carboxylated osteocalcin were found only in trained obese children with no significant relationship in control and untrained obese children.

CONCLUSIONS

In trained obese children, correlations indicate that when BMD is increased, osteocalcin is increased and insulin lowered. This suggests that increased BMD is associated with increased energy metabolism and a decreased level of insulin. We thus report statistically significant relationships between the skeleton (osteocalcin) and energy metabolism (insulin), suggesting a regulatory hormonal loop including osteocalcin and insulin.

Bone mass in a group of Lebanese girls from Beirut and French girls from Orleans

AIM OF THE STUDY

To compare bone mineral content (BMC) and bone mineral density (BMD) in a group of Lebanese girls from Beirut and French girls from Orléans.

METHODS

This study included 26 French adolescent girls (153 +/- 0.7 years old) and 24 maturation-matched (15.4 +/- 1.1 years old) Lebanese adolescent girls. BMC, BMD at the whole body (WB) and body composition (lean mass and fat mass) were assessed by dual-energy X-ray absorptiometry (DXA). Calculations of the bone mineral apparent density (BMAD) and the ratio BMC/height were completed for the WB. Weight and height were similar in the two groups.

RESULTS

Lean mass was higher in French girls compared to Lebanese girls (p < 0.05). In the whole population, lean mass was a positive determinant of BMC and BMD. French girls displayed higher values of BMC, BMD, BMC/height and BMAD than Lebanese girls (p < 0.05). Finally, BMC and BMD remained higher in French girls in comparison to Lebanese girls even after adjusting for lean mass.

CONCLUSION

In this study group, Lebanese girls have lower BMC and BMD in comparison to French girls.

Bone geometry and strength adaptations to physical constraints inherent in different sports: comparison between elite female soccer players and swimmers

Sports training characterized by impacts or weight-bearing activity is well known to induce osteogenic effects on the skeleton. Less is known about the potential effects on bone strength and geometry, especially in female adolescent athletes. The aim of this study was to investigate hip geometry in adolescent soccer players and swimmers compared to normal values that stemmed from a control group. This study included 26 swimmers (SWIM; 15.9 ± 2 years) and 32 soccer players (SOC; 16.2 ± 0.7 years), matched in body height and weight. A group of 15 age-matched controls served for the calculation of hip parameter Z-scores. Body composition and bone mineral density (BMD) were assessed by dual-energy X-ray absorptiometry (DXA). DXA scans were analyzed at the femoral neck by the hip structure analysis (HSA) program to calculate the cross-sectional area (CSA), cortical dimensions (inner endocortical diameter, ED; outer width and thickness, ACT), the centroid (CMP), cross-sectional moment of inertia (CSMI), section modulus (Z), and buckling ratio (BR) at the narrow neck (NN), intertrochanteric (IT), and femoral shaft (FS) sites. Specific BMDs were significantly higher in soccer players compared with swimmers. At all bone sites, every parameter reflecting strength (CSMI, Z, BR) favored soccer players. In contrast, swimmers had hip structural analysis (HSA) Z-scores below the normal values of the controls, thus denoting weaker bone in swimmers. In conclusion, this study suggests an influence of training practice not only on BMD values but also on bone geometry parameters. Sports with high impacts are likely to improve bone strength and bone geometry. Moreover, this study does not support the argument that female swimmers can be considered sedentary subjects regarding bone characteristics.

Influence of the weight status on bone mineral content and bone mineral density in a group of Lebanese adolescent girls

AIM

The aim of this study was to determine the influence of being overweight on whole-body (WB) bone mineral content (BMC) and bone mineral density (BMD) in a group of Lebanese adolescent girls.

METHODS

This study included 32 overweight (BMI>25 kg/m2) adolescent girls (15.3+/-2.3 years old) and 24 maturation-matched (15.7+/-1.7 years old) controls (BMI<25 kg/m2). Bone mineral area (BMA), BMC, BMD at the WB and body composition (lean mass and fat mass) were assessed by dual-energy X-ray absorptiometry (DXA). Calculation of the ratio BMC/height and bone mineral apparent density (BMAD) were completed for the WB.

RESULTS

Expressed as crude values, BMA, BMC and the ratio BMC/height were higher in overweight adolescent girls compared to controls. After adjusting for body weight, there were no differences in BMC or in the ratio BMC/height between the two groups. However, BMA was lower in overweight girls compared to controls. After adjusting for either lean mass or fat mass, there were no significant differences between the two groups regarding these variables: BMC, BMA, BMD, BMC/height and BMAD.

CONCLUSION

This study suggests that the positive effect of overweight on BMC is due to body weight. In fact, the difference in BMC between the overweight and the control girls disappears after adjusting for body weight. In contrast, overweight girls have lower BMA compared to controls when values are adjusted to body weight.

[Body mass index and quantitative osseous ultrasonography of the phalanges in Lebanese post-menarcheal adolescent girls]

AIM OF THE STUDY

To explore the relation between body mass index and phalanx ultrasound measurements in a group of Lebanese post-menarchal girls.

METHODS AND RESULTS

Amplitude-dependent speed of sound (AD-SoS) and bone transmission time (BTT) were measured in 168 post-menarchal girls aged 12-17 years using a DBM sonic bone profiler device. Anthropometrical characteristics (weight and height) were measured. Age and maturation index (years since menarche) were positively related to AD-SoS and BTT (p < 0.01). AD-SoS values were negatively related to BMI and body weight (r = -0,27; p < 0.001 and r = - 0,25; p < 0.001 respectively). There was no relation between BTT values and neither BMI nor body weight. Overweight girls (n = 36) had lower AD-SoS values than normal-weight girls (n = 122) (1994 +/- 87 m x sec(-1) vs 2041 +/- 82 m x sec(-1) respectively; p < 0.01). Obese girls (n = 10) had lower AD-SoS values than normal-weight girls (n = 122) (1976 +/- 96 m x sec(-1) vs 2041 +/- 82 m x sec(-1) respectively; p < 0.05).

CONCLUSION

In this group of Lebanese post-menarchal girls, AD-SoS values are inversely correlated to BMI while BTT values were not related to BMI.

[Daily calcium intake and body mass index in a group of Lebanese adolescents]

AIM OF THE STUDY

To investigate the relationship between daily calcium intake (DCI) and body mass index (BMI) in a group of Lebanese adolescents.

METHODS AND RESULTS

419 adolescents (219 boys and 169 girls) aged 13-18 years participated in our study. DCI was calculated using a validated questionnaire, and anthropometrical characteristics (weight and height) were measured. In this study, only 20% of the adolescents met the adequate DCI recommendation of 1300 mg/day. Boys had a significantly higher mean DCI than girls (1023 +/- 360 mg/d and 839 +/- 303 mg/d respectively for boys and girls ; p < 0.001). DCI was negatively related to BMI in boys (r = -0,15; p < 0.05) but not in girls. Obese boys had a significantly lower mean DCI than those whose BMI was normal (869 +/- 249 mg/d and 1043 +/- 373 mg/d respectively ; p < 0.05).

CONCLUSION

In this study, 80% of the adolescents do not meet the DCI adequate intake. It seems important to encourage these adolescents to increase their DCI. Moreover, this study shows that DCI is inversely related to age in girls and to BMI in boys.

Does exercise modify the effects of zoledronic acid on bone mass, microarchitecture, biomechanics, and turnover in ovariectomized rats?

Regular activity has effects on bone size, shape, and density, resulting in an increase in mechanical strength. The mechanism of action that underlies this improvement in bone strength is mainly linked to an increase in bone formation. Zoledronic acid (Z), in contrast, may prevent bone strength changes in ovariectomized (OVX) rodents by its potent antiresorptive effects. Based on these assumptions we hypothesized that combined effects of exercise (E) and Z may produce higher benefits on bone changes resulting from estrogen deficiency than either intervention alone. At 6 months of age, 60 female Wistar rats were OVX or sham operated (SH) and divided into five groups: SH, OVX, OVX-E, OVX-Z, and OVX-ZE. OVX rats were treated with a single IV injection of Z (20 microg/kg) or vehicle and submitted or not to treadmill exercise (15 m/min, 60 min/day, 5 days/week) for 12 weeks. Whole-body BMD and bone turnover markers were analyzed longitudinally. At sacrifice, femurs were removed. BMD by DXA, three-point bending test, and microCT were performed to study biomechanical and trabecular structure parameters, respectively. After 12 weeks, bone volume fraction decreased in OVX rats, whereas bone turnover rate, trabecular spacing, and structure model index increased compared with those in the SH group (P < 0.05). Zoledronic acid prevented the ovariectomy-induced trabecular bone loss and its subsequent trabecular microarchitectural deterioration. Treadmill exercise running was shown to preserve the bone strength and to induce bone turnover changes in favor of bone formation. However, the combined effects of zoledronic acid and running exercise applied simultaneously did not produce any synergetic or additive effects.

Total body, lumbar spine and hip bone mineral density in overweight adolescent girls: decreased or increased?

Despite the epidemic of overweight adolescents, the effect of being overweight on bone mineral density (BMD) during this period is poorly understood. However, recent studies have suggested that overweight adolescents have lower BMD compared to normal-weighted adolescents after adjusting for body weight. The aim of this study was to determine the influence of being overweight on bone status in a group of adolescent girls. This study included 22 overweight (BMI >25 kg/m(2)) adolescent girls (15.4 +/- 2.4 years old) and 20 maturation-matched (15.2 +/- 1.9 years old) controls (BMI <25 kg/m(2)). Bone mineral area, bone mineral content, BMD at the whole body (WB), lumbar spine (L2-L4), femoral neck (FN), total hip (TH) and body composition (lean mass and fat mass) were assessed by dual-energy X-ray absorptiometry (DXA). Calculation of the bone mineral apparent density (BMAD) was completed for the WB and for L2-L4. Expressed as crude values, DXA measurements of BMD at all bone sites (TB, L2-L4, TH and FN) were higher in overweight adolescent girls compared to controls. After adjusting for either body weight, lean mass or fat mass, these differences disappeared. Finally, BMAD of the L2-L4 remained higher in overweight girls compared to controls after adjusting for lean mass. We conclude that overweight adolescent girls do not have lower BMD when compared with controls, even when BMD values are adjusted for weight, lean mass or fat mass.

[Leptin, insulin, IGF-1 and bone mass in a group of sedentary adolescent girls]

AIM OF THE STUDY

To investigate the relationships between serum leptin, IGF-1, insulin and bone mineral content and density in a group of Lebanese sedentary adolescent girls.

METHODS AND RESULTS

Twenty Lebanese sedentary adolescent girls participated in our study. Total body bone mineral content and density were measured by dual-energy X-ray absorptiometry (DEXA). In parallel, fasting leptin, IGF-1 and insulin concentrations were also measured. Serum leptin, IGF-1 and insulin concentrations were not associated with total body bone mineral content (BMC), total body bone mineral density (BMD) or pelvis BMD.

CONCLUSION

Serum leptin, IGF-1 and insulin concentrations are not positive predictors of total body bone mineral content or density in this study group.

Preserved Bone Health in Adolescent Elite Rhythmic Gymnasts despite Hypoleptinemia

BACKGROUND/AIMS

Leptin is linked to hormonal disturbances occurring in anorexia and positively linked with bone mineral density. The aim of this study was to determine whether hypoleptinemia occurring in rhythmic gymnasts may affect bone health.

METHOD

Leptin, insulin, cortisol, IGF1 levels and bone markers were determined in 36 rhythmic gymnasts (EG) and 20 controls (C). Body composition, BMD at the whole body (WBBMD), lumbar spine (LSBMD) and bone ultrasound properties (SOS, BUA) were measured.

RESULTS

The rhythmic gymnasts had lower fat mass and leptin level than the controls. There was no difference for IGF1, cortisol and insulin levels. Bone turnover rate was higher in elite gymnasts. The uncoupling index showed that remodeling favored the bone formation. LSBMD, WBBMD, SOS and BUA were higher in elite gymnasts after adjustment for fat mass. Leptin correlated positively with fat mass and negatively with physical activity.

CONCLUSION

High impact training is able to counterbalance bone effects usually encountered in hormonally disturbed subjects. Our results suggest that hypoleptinaemia might be related to direct osteogenic effects and indirect hormonal mechanisms including preservation of IGF and cortisol levels.

The mode of bone conservation does not affect the architecture and the tensile properties of rat femurs

The bone samples used in clinical and experimental trials must be the less damaged as possible to avoid alterations of their properties. However, the mode of storage might possibly alter the bone properties, particularly microarchitecture and strength. The aim of our study was to analyze the effects of deep-freezing and alcohol conservation techniques on the densitometric, microarchitectural and biomechanical parameters of rat femurs. The left femurs were elongated in uniaxial tension up to breakdown in order to calculate biomechanical parameters. The densitometric and microarchitectural properties of right femurs were evaluated using dual-energy X-ray absorptiometry and microcomputed tomography, respectively. Results showed no significant difference in the parameters investigated between deep-freezing, alcohol storage and fresh femurs when comparing each parameter separately. Therefore, one month storage in alcohol or deep-freezing seemed to induce no harmful effect on densitometric, microarchitectural and biomechanical parameters of rat femurs.

Cumulative effects of calcium supplementation and physical activity on bone accretion in premenarchal children: a double-blind randomised placebo-controlled trial

High calcium intake combined with physical activity during childhood have been shown to improve bone mass accrual and bone mineral density. Our aim was to study the combined effect of calcium and exercise on bone gain in children. Two milk-powder products containing either 800 mg of calcium phosphate (calcium) or not (placebo) were randomly allocated to 113 healthy premenarchal girls on a daily basis for 1 year. The group was composed of 63 exercise (7.2 +/- 4 hours of exercise/week) and 50 sedentary (1.2 +/- 0.8 hours of exercise/week) children. The final experiment had 4 groups: exercise/calcium (n = 12), exercise/placebo (n = 42), sedentary/calcium (n = 10), and sedentary/placebo (n = 21). Bone mineral density (BMD) at 6 skeletal sites and body composition were determined by DXA. Bone age was calculated and the daily spontaneous calcium intake was assessed by a frequency questionnaire. All the tests were performed at baseline and 1 year by the same observer. BMD gains were significantly greater in the exercise/calcium group than in other groups at the total body (increase of 6.3 %, p < 0.05), lumbar spine (11 %, p < 0.05), femoral neck (8.2 %, p < 0.02), and Ward's triangle (9.3 %, p < 0.01). There was no difference between the other groups. These data suggest that calcium supplementation increases the effect of physical exercise on bone mineral acquisition in the period preceding puberty, and that calcium supplementation without physical activity does not improve the BMD acquisition during this period. Physical exercise that stimulates bone accretion needs a high calcium intake to be completely effective.

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.

Effects of Long-Term Tennis Playing on the Muscle-Bone Relationship in the Dominant and Nondominant Forearms

The relationship between muscle strength and bone mineral density illustrates the positive effect of mechanical loading on bone. But local and systemic factors may affect both muscle and bone tissues. This study investigated the effects of long-term tennis playing on the relationship between lean tissue mass and bone mineral content in the forearms, taking the body dimensions into account. Fifty-two tennis players (age 24.2 ± 5.8 yrs, 16.2 ± 6.1 yrs of practice) were recruited. Lean tissue mass (LTM), bone area, bone mineral content (BMC), and bone mineral density were measured at the forearms from a DXA whole-body scan. Grip strength was assessed with a dynamometer. A marked side-to-side difference (p <  0.0001) was found in favor of the dominant forearm in all parameters. Bone area and BMC correlated with grip strength on both sides (r = 0.81-0.84, p <  0.0001). The correlations were still significant after adjusting for whole-body BMC, body height, or forearm length. This result reinforced the putative role of the muscles in the mechanical loading on bones. In addition, forearm BMC adjusted to LTM or grip strength was higher on the dominant side, suggesting that tennis playing exerts a direct effect on bone. Key words: bone mineral content, muscle strength, unilateral loading, mechanical stress, absorptiometry

Effects of chronic intensive training on androgenic and cortisol profiles in premenarchal female gymnasts

The effect of intensive exercise training on urinary androgen and cortisol excretions in prepubertal girls of various ages was tested in competitive premenarchal gymnasts ( n=56) and in age-matched controls ( n=53). Both sexual maturation and bone age were assessed. Urinary excretions of androstenedione, dehydroepiandrosterone sulphate (DHEA-S), testosterone and cortisol were determined by radioimmunoassay procedures. The gymnasts were taller [mean (SD) 138.3 (9.0) cm vs 144.7 (8.3) cm; P<0.001] and lighter [32.0 (6.9) kg vs 36.7 (8.2) kg; P<0.001], and had a lower percentage of fat mass [16.8 (2.2)% vs 22.5 (6.6)%; P<0.0001] than the controls. There was no difference between groups in urinary testosterone, cortisol and DHEA-S levels, while androstenedione levels were significantly lower in gymnasts than in controls [mean (SEM) 187.10 (18.00) nmol/24 h vs 256.50 (15.00) nmol/24 h; P<0.01). There was no difference in the regression slopes between the two groups for all hormonal values. In conclusion, these results suggest that during the prepubertal period, intensive training alters only urinary androstenedione concentrations in girls.

High-impact loading training induces bone hyperresorption activity in young elite female gymnasts

The aim of this study was to investigate the effect of intensive exercise on bone turnover (as reflected by bone resorption) in young elite female gymnasts. Forty-five healthy girls including 24 gymnasts (11.9+/-2 yr) and 21 controls (12.3+/-1.4 yr) were studied. Body weight, height, bone age and body composition were measured. Bone mineral density (BMD) was assessed at the whole body, lumbar vertebrae, hip and radius by means of DXA. Volumetric density (BMAD) was calculated. Bone velocity (SOS) and attenuation (BUA) were measured by QUS at the calcaneus. Urinary androstenedione (delta4), dehydroepiandrosterone sulfate (DHEA-S), and CrossLaps (CTx) were measured. BMD and BMAD were significantly greater in the gymnasts at all sites except whole body. SOS was found significantly higher. Delta4 values were significantly lower in the gymnasts. The distribution of the subjects according to Tanner stages was not different between groups. CTx levels were significantly higher in the gymnasts (989.08+/-154.63 microg/mmol Cr.) vs controls (580.25+/-123.99 microg/mmol Cr., p=0.02). CTx values decreased from Tanner stage 1 to stage 4 in each group, the gymnasts' levels always being higher than those of the controls. In conclusion, gymnastics seems to stimulate bone resorption activity in highly-trained young females. The coexistence of bone hyperresorption and higher BMD in gymnasts suggests increased bone turnover resulting in increased bone density in these subjects.