Georges El Khoury

Physical Performance Variables and Bone Mineral Density in a Group of Young Overweight and Obese Men

The aim of this study was to explore the relationships between performances obtained in different physical tests and bone parameters (bone mineral density [BMD], bone mineral content, hip geometry indices, and trabecular bone score [TBS]) in a group of young Lebanese overweight and obese adult men. Fifty-two overweight and/or obese (body mass index > 25 kg/m2) young men whose ages range from 18 to 35 yr participated in this study. Weight and height were measured, and body mass index was calculated. Body composition, BMD, cross-sectional area and section modulus (Z) of the femoral neck (FN), and TBS were measured by dual-energy X-ray absorptiometry. Maximum oxygen consumption (VO2 max, in liter per minute) was determined by direct measurement while exercising on a medical treadmill. One-repetition-maximum half-squat and maximum power (P max) of the lower limbs were measured using validated exercises. Lean mass was a positive determinant of whole-body bone mineral content (r = 0.71, p < 0.001), FN cross-sectional area (r = 0.51, p < 0.001), and FN Z (r = 0.58, p < 0.001). VO2 max (in liter per minute) was a positive determinant of whole-body BMD (r = 0.47, p < 0.001), total hip BMD (r = 0.43, p < 0.01), and FN BMD (r = 0.42, p < 0.01). VO2 max (in milliliter per minute per kilogram) was a positive determinant of TBS (r = 0.30, p < 0.05). One repetition maximum was a positive determinant of L1-L4 BMD (r = 0.33, p < 0.05). This study suggests that VO2 max (in liter per minute) is a positive determinant of BMD, and VO2 max (in milliliter per minute per kilogram) is a positive determinant of TBS in overweight and obese men.

Decreased Composite Indices of Femoral Neck Strength in Young Obese Men

The aim of the current study was to compare compression strength index (CSI), bending strength index (BSI) and impact strength index (ISI) among obese, overweight and normal-weight young women. 117 young women (20 obese, 36 overweight and 61 normal-weight) whose ages range from 18 to 35 years participated in this study. Body composition and BMD were evaluated by dual-energy X-ray absorptiometry (DXA). CSI, BSI and ISI values were significantly lower in obese and overweight women compared to normal-weight women (p < 0.001). In the whole population (n = 117), body mass index (BMI) was negatively correlated to CSI (r = −0.66; p < 0.001), BSI (r = −0.56; p < 0.001) and ISI (r = −0.54; p < 0.001). This study suggests that obesity is associated with lower CSI, BSI and ISI values in young women.

Maximal Oxygen Consumption and Composite Indices of Femoral Neck Strength in a Group of Young Overweight and Obese Men

Several studies have shown positive associations between anaerobic power and bone strength variables (1–4). However, little is known concerning the relation between aerobic power and bone strength in young adults (5–10). Maximal oxygen uptake (VO2 max) is the maximum rate of oxygen consumption as measured during incremental exercise (5–10).VO2 max is widely accepted as the single best measure of cardiovascular fitness and maximal aerobic power (5–10). VO2 max is expressed either as an absolute rate (liter per minute) or as a relative rate (milliliter per minute per kilogram) (5–10). Bone mineral density (BMD) is generally considered as the best determinant of bone strength (11). However, only 50%–70% of bone strength variability can be explained by BMD (11–13). Hip bone strength is also influenced by other factors such as femoral neck (FN) width and bending strength (11–13).Karlamangla et al (14) have examined the prediction of incident hip fracture risk by composite indices of FN strength (compression strength index [CSI], bending strength index [BSI], and impact strength index [ISI]) constructed from dual-energy X-ray absorptiometry scans of the hip.These indices integrate FN size and body size with bone density (14). CSI, BSI, and ISI reflect the ability of the FN to withstand axial compressive and bending forces and to absorb energy from an impact (14–21).These indices have been shown to improve hip fracture risk and bone strength assessments in the elderly (14–16). In children and young adults, physical activity practice positively influences these indices (18–20). In a recent study, we have shown that obesity is associated with low composite indices of FN strength in young obese men (21).Overweight and obese subjects seem to have low VO2 max (milliliter per minute per kilogram) values (22). However, little is known concerning the relation between maximal oxygen consumption and composite indices of FN strength in young obese adults. The aim of the current study was to explore the relationship between maximal oxygen consumption and composite indices of FN strength in a group of young overweight and obese men. Seventy-three overweight and obese (body mass index > 25 kg/m) young men whose ages ranged from 18 to 35 yr participated in the present study.The 73 participants were recruited from3 private universities located inNorthLebanon. All participants were nonsmokers and had no history ofmajor orthopedic problems or other disorders known to affect bone metabolism or physical tests of the study.Other inclusion criteria included no diagnosis of comorbidities and no history of fracture.An informed written consent was obtained from the participants.The current study was approved by the University of BalamandEthics Committee.Bonemineral content and BMD were determined for each individual by dualenergy X-ray absorptiometry at whole body, total hip, and FN (GE Healthcare, Madison, WI). Composite indices of FN strength (CSI,BSI, and ISI) were calculated as previously described (14). We directly assessed the VO2 max of the participants using a Cosmed Fitmate Pro device (version 2.20, Cosmed, Rome, Italy) while exercising on a bicycle ergometer (Siemens-Elema RE 820; Rodby Elektronik AB, Enhorna, Sweden). A progressive 2-min step protocol (20–30W/step) was used as previously described (23). VO2 max (milliliter per minute per kilogram) was positively correlated to CSI (r = 0.51, p < 0.001), BSI (r = 0.28, p < 0.05), and ISI (r = 0.48, p < 0.001). The positive associations between VO2 max (milliliter per minute per kilogram) and 2 indices (CSI and ISI) remained significant after controlling for body mass index using multiple linear regression models. To our knowledge, this is the first study to show positive associations between maximal oxygen consumption (milliliter per minute per kilogram) and composite indices of FN strength in young overweight and obese men. Enhancing cardiovascular fitness may help to reduce osteoporotic fractures in overweight and obese men.

Bone Variables in Active Overweight/Obese Men and Sedentary Overweight/Obese Men

The aim of this study was to compare bone variables in active overweight/obese men and sedentary overweight/obese men. Thirty-seven active overweight/obese men and 45 sedentary overweight/obese men participated in this study. Weight and height were measured, and body mass index was calculated. Body composition and bone variables (bone mineral content [BMC], bone mineral density [BMD], geometric indices of hip bone strength, and trabecular bone score) were measured by DXA. Physical activity level, daily calcium intake, daily protein intake, and sleep duration were measured by validated questionnaires. Maximum oxygen consumption (VO2 max) was determined by direct measurement while exercising on a medical treadmill. One-repetition-maximum half-squat of the lower limbs was measured using a validated protocol. Body weight and body mass index were higher in sedentary overweight/obese men than in active overweight/obese men. In the whole population (n = 82), VO2 max (in liter per minute), lean mass, and one-repetition-maximum half-squat were positively correlated to BMC, BMD, and geometric indices of hip bone strength (cross-sectional area and section modulus [Z] of the femoral neck [FN]). After adjusting for body weight using a 1-way analysis of covariance, active overweight/obese men displayed higher whole-body BMC, lumbar spine BMD, total hip BMD, FN BMD, FN cross-sectional area, and FN Z values than sedentary overweight/obese men. In conclusion, the current study suggests that physical activity level positively affects bone variables in overweight/obese men. Optimizing lean mass and muscular strength of the lower limbs can help to prevent osteoporosis in overweight and obese men.

Trabecular Bone Score in Overweight and Normal-Weight Young Women

The aim of this study was to compare Trabecular Bone Score (TBS) in overweight and normal-weight young women. This study included 14 overweight (BMI > 25 kg/m2) and 42 normal-weight (BMI < 25 kg/m2) young Lebanese women whose ages range from 18 to 32 years. Body composition, Bone Mineral Content (BMC), Bone Mineral Density (BMD), and lumbar spine (L1–L4) TBS were assessed by dual-energy X-ray asborptiometry (DXA). The DXA measurements were completed for the whole body (WB), the lumbar spine (L1–L4), the total hip (TH) and the femoral neck (FN). Physical activity, daily calcium intake, daily protein intake and sleep quality index were evaluated using validated questionnaires. Maximal oxygen consumption (VO2 max in l/mn) was measured whilst exercising on a bicycle ergometer using a specialized device. Weight, height, BMI, lean mass, fat mass, WB BMC, WB BMD, TH BMD and FN BMD were significantly higher in overweight women compared to normal-weight women. Trabecular Bone Score (TBS) was not significantly different between the two groups (overweight and normal-weight). In the whole population (n = 56), weight, height, BMI, lean mass and fat mass were positively correlated to BMC and BMD values but not to TBS values. VO2 max (l/mn) was positively correlated to BMC, BMD and TBS (p < 0.05). This study suggests that being overweight is not associated with higher trabecular bone score values in young women.

Maximal Oxygen Consumption and Composite Indices of Femoral Neck Strength in a Group of Young Women

The aim of this study was to explore the relationship between maximal oxygen consumption (VO2 max; mL/mn/kg) and composite indices of femoral neck strength in a group of young women. 41 young women whose ages ranged from 18 to 35 years participated in the present study. Femoral neck bone mineral density was measured by DXA. Composite indices of femoral neck strength (CSI, BSI and ISI) were calculated. VO2 max (mL/mn/kg) of the participants was measured using a Cosmed Fitmate pro device (version 2.20) while exercising on a bicycle ergometer (Siemens-Elema RE 820; Rodby Elektronik AB, Enhorna, Sweden). VO2 max (mL/mn/kg) was positively correlated to CSI (r = 0.52; p < 0.001) and ISI (r = 0.45; p < 0.01). The positive associations between VO2 max (mL/mn/kg) and these two indices (CSI and ISI) remained significant after controlling for body mass index using multiple linear regression models.

Vitamin D Level and Composite Indices of Femoral Neck Strength in a Group of Young Lebanese Women

Low serum vitamin D is associated with low bone mineral density (BMD), which is an important predictor of fracture risk (1–6). However, hypovitaminosis D is a prevalent disorder in the Lebanese population (7–13). BMD is generally considered as the best determinant of bone strength and can therefore practically predict fracture risk (14). However, only 50%–70% of bone strength variability can be explained by BMD (15). Hip bone strength is also influenced by other factors such as femoral neck (FN) width and bending strength (16). Karlamangla et al (17) have examined the prediction of incident hip fracture risk by composite indices of FN strength (compression strength index [CSI], bending strength index [BSI], and impact strength index [ISI]) constructed from dualenergy X-ray absorptiometry (DXA) scans of the hip. These indices integrate FN size and body size with bone density (17). CSI, BSI, and ISI reflect the ability of the FN to withstand axial compressive and bending forces and to absorb energy from an impact (17). These indices have been shown to improve hip fracture risk and bone strength assessments in the elderly (17–19). In children and young adults, physical activity practice positively influences these indices (20–23). In a recent study, we have shown that obesity is associated with low composite indices of FN strength in young obese men (24). The aim of the present study was to explore the relationships between serum vitamin D and composite indices of FN strength in a group of young Lebanese men. A total of 116 young Lebanese men (43 obese, 51 overweight, and 22 normal weight) whose ages ranged from 18 to 35 yr participated in the current study. Normal weight, overweight, and obesity are defined by a body mass index (BMI) between 20.0 and 24.9 kg/m, between 25.0 and 29.9 kg/m, and 30 kg/m or more, respectively. The participants were recruited from 3 private universities located in North Lebanon. All participants were nonsmokers and had no history of major orthopedic problems or other disorders known to affect bone metabolism or physical tests of the study. Other inclusion criteria included no diagnosis of comorbidities and no history of fracture. An informed written consent was obtained from the participants. The study was approved by the University of Balamand Ethics Committee. Bone mineral content and BMD were determined for each individual by DXA at whole body, lumbar spine (L1–L4), total hip, and FN (GE Healthcare, Madison,WI). Body composition and trabecular bone score were also evaluated by DXA. Composite indices of FN strength (CSI, BSI, and ISI) were calculated as previously described (17–19). Serum 25-hydroxyvitamin D level was measured by the Nichols Advantage competitive binding chemiluminescence immunoassay (25). Vitamin D insufficiency is defined as a 25(OH)D concentration of <30 ng/mL (26). The mean serum vitamin D level of the studied population was 27.3 ± 12.4 ng/mL. Overall, 65.6% of the subjects were vitamin D insufficient (serum vitamin D < 30 ng/mL). In the whole population (n = 116), serum vitamin D was negatively correlated to body weight (r = −0.33, p < 0.01), BMI (r = −0.30, p < 0.01), fat mass (r = −0.31, p < 0.01), and fat mass percentage (r = −0.26, p < 0.05), but positively correlated to CSI (r = 0.28,p < 0.01), BSI (r = 0.22, p < 0.05), and ISI (r = 0.19, p < 0.05). Serum vitamin D was not significantly correlated to bone mineral content, BMD, or trabecular bone score values. Vitamin D-sufficient men (n = 40) had a significantly higher CSI than vitamin D-insufficient men (n = 76). Our results are in accordance with those reported by Kim et al (27) in Korean women aged ≥50 years. Given that our study sample included obese, overweight, and normal-weight subjects, future larger studies are necessary to confirm whether the relation between serum vitamin D and CSI is independent of or dependent on BMI. Our study suggests that serum vitamin D is a positive but weak determinant of composite indices of FN strength in young men. To our knowledge, this is the first study to find positive correlations between serum vitamin D and composite indices of FN strength in young men. Optimization of serum vitamin D levels may be associated with greater composite indices of FN strength in young Lebanese men. Our study provides an additional evidence of vitamin D on bone health.

Performance Physique et Densité Minérale Osseuse chez de Jeunes Adultes Libanais

Introduction The aim of this study was to explore the relationships between performances obtained in different physical tests and bone parameters (bone mineral density (BMD) and bone mineral content (BMC)) in a group of young Lebanese adults. Methods One hundred and six young Lebanese adults (45 women and 61 men) whose ages range from 17 to 34 years participated in this study. Weight and height were measured, and body mass index (BMI) was calculated. Daily calcium intake, daily protein intake and physical activity level (h/week) were evaluated using validated questionnaires. The level of physical performance was measured using several physical tests: vertical-jump test, standing long jump test, 3-jumptest, 5-jump-test and 1-RM half-squat. Body composition, bone mineral content (BMC) and BMD at whole body (WB), lumbar spine (L2-L4), total hip (TH) and femoral neck (FN) were measured by dual-energy X-ray absorptiometry (DXA). Results In women, height, lean mass, 1- RM half-squat and performances obtained in three physical tests (vertical jump test, 5-jump-test and 1-RM halfsquat) were positively correlated to BMD and BMC. In men, lean mass and 1-RM half-squat were positively correlated to BMD and BMC. Conclusion This study suggests that lean mass and maximum strength obtained in half-squat are positively correlated to BMD in young adults.