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Military personnel engage in vigorous exercise, often resulting in higher bone mineral density; however, leg bone injuries occur frequently in this population. Predictors of change in tibial bone quality and strength need to be characterized in this high-risk population. To examine the effects of an 8-week military training intervention on total body and site-specific bone density and tibial bone quality, serum biomarkers (parathyroid hormone and sclerostin), body composition, and physical performance and to investigate which outcome variables (biomarkers, body composition, and physical performance) predict estimated tibial bone strength in college-aged Reserve Officers' Training Corps (ROTC) participants. Prospective cohort study. University of Oklahoma. The ROTC participants (14 males, 4 females) were matched for sex, age, and mass to physically active control participants (14 males, 4 females). The ROTC participants engaged in an 8-week training intervention, while the physically active control group made no changes to their exercise routines. Preintervention general health questionnaires were completed. Pre-, mid-, and postintervention bone scans (dual-energy x-ray absorptiometry and peripheral quantitative computed tomography); serum blood draws (parathyroid hormone and sclerostin); and physical performance measures (muscle strength and aerobic capacity) were obtained. The ROTC participants exhibited increased hip bone density mineral and content (both P values ≤.02) after the 8-week intervention. Sclerostin, but not parathyroid hormone, was a positive correlate and predictor in all ROTC models for estimated bone strength at the fracture-prone 38% tibial site (ie, 38% of the tibial length proximal to the distal end of the tibia). Both groups displayed decreased total body and regional fat mass, and ROTC participants' aerobic capacity increased (all P values ≤.05). All bone, body composition, and performance measures either improved or were maintained in response to ROTC training. Sclerostin should be further investigated as a potential early indicator of changes in estimated tibial bone strength in military cohorts. [ABSTRACT FROM AUTHOR]

Baker, BS, Buchanan, SR, and Bemben, DA. Skeletal health and associated injury risk in collegiate female rowers. J Strength Cond Res 36(4): 1125-1133, 2022-Rowing has been associated with low bone mass and stress fractures. The aim of this study was to compare bone density, geometry, and skeletal asymmetries between competitive female rowers and matched controls and within rowers based on reported injury status, allowing for the calculation of practical injury risk prediction equations. Rowers (n = 24) and controls (n = 24) completed total body, lumbar spine, and and dual femur and radii dual energy x-ray absorptiometry and peripheral quantitative computed tomography scans. One-way analyses of covariance were performed between rowers and controls, and one-way analyses of variance were performed between rowers based on reported rib injury status (injured [ n = 11]; injury-free [ n = 13]). Logistic regression was used to create prediction models of rowers' injury status. Significance was set at p <= 0.05. Rowers were taller, had greater lean mass, less fat mass, and mostly equivalent skeletal measures compared to controls, which were within normal ranges (p < 0.048). Injury-free rowers consumed over 500 mg[middle dot]d-1 more calcium and were less symmetrical at the 4% tibiae and hips (p < 0.015). The strongest predictive regression model of reported rib injury in rowers comprised calcium intake and the symmetry index of hip strength index (R 2 = 0.833; p < 0.001). A more practical model including daily calcium intake and total bone specific physical activity (PA) scores can be used to correctly predict injury status 75% of the time (R 2 = 0.750; p = 0.022). This is the first study to provide practitioners an injury prediction model for competitive rowers, reiterating the importance of proper nutrition and auxiliary PA focusing on balanced movement patterns. /> [ABSTRACT FROM AUTHOR]

Military personnel experience elevated bone injury incidence, partly due to arduous and repetitive training. Non-traditional High-Intensity Interval Training-style (HIIT) may benefit pre-enlisted Reserve Officer Training Corps (ROTC) cadet's musculoskeletal health and performance prior to military service. This study investigated 16 ROTC (n = 12 males; n = 4 females) and 15 physically active sex-, age-, and body mass-matched Controls' musculoskeletal health and performance from November to April. Total body, lumbar spine, and dual- hip dual-energy X-ray absorptiometry scans and 4%, 38%, 66% tibial peripheral quantitative computed tomography scans, blood draws (serum sclerostin and parathyroid hormone), and maximal muscle strength and aerobic capacity testing were completed. From November to April, ROTC improved bone density (DXA) of the dominant total hip and greater trochanter and non-dominant greater trochanter and 38% and 66% tibial total volumetric and cortical bone density (pQCT) similarly or more than Controls (all p ≤ 0.049). From November to April, ROTC also improved bench and leg press, and peak aerobic capacity (all p ≤ 0.013). From November to January, serum sclerostin increased (p ≤ 0.007) and remained elevated through April, while parathyroid hormone was unchanged. HIIT-style training induced positive musculoskeletal adaptations, suggesting it may be an excellent pre-service training modality for this injury prone group. [ABSTRACT FROM AUTHOR]

This cross-sectional study examined the associations between serum interleukin-6 (IL-6) and muscle, bone, and fat parameters in recreationally active women. One-hundred forty-five women (48.7 ± 17.8 years; 164.4 ± 7.1 cm; 66.8 ± 10.7 kg; and 24.7 ± 3.9 kg/m2) underwent dual energy x-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) assessments to determine total and regional muscle, bone, and fat parameters. Muscle performance of the knee extensors was examined via isometric, isotonic, and isokinetic dynamometry assessments, and serum IL-6 was measured via enzyme linked immunosorbent assay. Serum IL-6 was inversely associated with thigh muscle cross-sectional area (mCSA, r = -0.28, p < 0.01); isometric strength (r = -0.19, p < 0.05); hip areal bone mineral density [aBMD] (r = -0.18, p < 0.05); trochanter aBMD (r = -0.23, p < 0.01); total body aBMD (r = -0.20, p < 0.05); cortical volumetric bone density at 38 and 66% tibia (r = -0.18 and r = -0.19, respectively, both p < 0.05), and 66% cortical thickness (r = -0.17, p < 0.05). These associations were present after adjusting for age, BMI, and physical activity. Thigh mCSA was significantly lower in the tertile possessing the greatest IL-6 compared to the lowest tertile (p < 0.01); after adjusting for age, body mass index, and physical activity. Collectively, these observations indicate that IL-6 is inversely associated with skeletal muscle and bone parameters independent of relevant confounders. These observations bolster the prognostic value of serum IL-6. [ABSTRACT FROM AUTHOR]

Few data exist identifying the influence of age on midthigh muscle composition. Further understanding how muscle composition of the midthigh changes with aging may improve current exercise prescriptions. PURPOSE: To examine the influence of chronological age on midthigh composition in 142 women (49.1±17.7 years, 164.5±7.1 cm, 66.6±10.7 kg). METHODS: Midthigh peripheral quantitative computed tomography scans were completed at the 40% site of the right femur and were analyzed using BoneJ software. Muscle density (MuD), cross-sectional area (mCSA), and intramuscular fat area (IMAT) were derived from the scans. One-way ANOVA compared group means by decade 20-29 (n=28), 30-39 (n=21), 40-49 (n=22), 50-59 (n=25), 60-69 (n=29), ≥70 years (n=17), while Dunnett's test performed post-hoc pairwise comparisons with the youngest group. Spearman's correlations examined each parameters association with age. A significance level of p<0.05 was selected a priori. RESULTS: MuD and mCSA displayed significant negative associations with age (r=-0.58 and r=-0.67, respectively, both p<0.01), while IMAT displayed a significant positive association with age (r=0.17, p=0.04). Group differences were observed for MuD (p<0.01), mCSA (p<0.01), IMAT (p=0.029). Dunnett's test revealed that MuD was significantly greater in the 20-29 years group compared to both age groups ≥60 years (81.5±1.2mg/cm³ vs 79.1±2.2mg/cm³ and 78.2±2.9mg/cm³, respectively; both p<0.01), and mCSA was significantly greater in the 20-29 years group compared to each age group ≥50 years (104.4±15.4cm² vs 85.9±14.3cm², 78.8±12.4cm², and 72.3±14.5cm², respectively, all p<0.01). IMAT was significantly greater in ≥70 years group compared to the 20-29 years group (6.23±2.3cm² vs 4.3±1.8cm², p=0.04). Interestingly, MuD, a surrogate for muscle quality, displayed smaller age-related decreases than mCSA (MuD: -3.9% vs mCSA: -29.7%) between the 20-29 and ≥70 years group. CONCLUSIONS: The current observations reveal that increased age displayed significant associations with midthigh muscle composition (MuD, mCSA, IMAT). However, future research is needed to identify which muscle composition parameter(s) contribute most effectively to maintaining muscle strength and physical performance with advanced age. [ABSTRACT FROM AUTHOR]