The Influence of High-Impact Exercise on Cortical and Trabecular Bone Mineral Content and 3D Distribution Across the Proximal Femur in Older Men: A Randomized Controlled Unilateral Intervention

Abstract

Regular exercisers have lower fracture risk, despite modest effects of exercise on bone mineral content (BMC). Exercise may produce localized cortical and trabecular bone changes that affect bone strength independently of BMC. We previously demonstrated that brief, daily unilateral hopping exercises increased femoral neck BMC in the exercise leg versus the control leg of older men. This study evaluated the effects of these exercises on cortical and trabecular bone and its 3D distribution across the proximal femur, using clinical CT. Fifty healthy men had pelvic CT scans before and after the exercise intervention. We used hip QCT analysis to quantify BMC in traditional regions of interest and estimate biomechanical variables. Cortical bone mapping localized cortical mass surface density and endocortical trabecular density changes across each proximal femur, which involved registration to a canonical proximal femur model. Following statistical parametric mapping, we visualized and quantified statistically significant changes of variables over time in both legs, and significant differences between legs. Thirty-four men aged mean (SD) 70 (4) years exercised for 12-months, attending 92% of prescribed sessions. In traditional regions of interest, cortical and trabecular BMC increased over time in both legs. Cortical BMC at the trochanter increased more in the exercise than control leg, whereas femoral neck buckling ratio declined more in the exercise than control leg. Across the entire proximal femur, cortical mass surface density increased significantly with exercise (2.7%; p < 0.001), with larger changes (> 6%) at anterior and posterior aspects of the femoral neck and anterior shaft. Endocortical trabecular density also increased (6.4%; p < 0.001), with localized changes of > 12% at the anterior femoral neck, trochanter, and inferior femoral head. Odd impact exercise increased cortical mass surface density and endocortical trabecular density, at regions that may be important to structural integrity. These exercise-induced changes were localized rather than being evenly distributed across the proximal femur.

Reduction of trabecular and cortical volumetric bone mineral density at the proximal femur in patients with acromegaly

“…vBMD was obtained from the hip QCT analysis performing the following automated steps i) extraction of the proximal femur and ii) rotation and segmentation of bone voxels from soft tissue in three planes (axial, sagittal, and coronal). For each scan at each time point, a fixed threshold (450 mg/cm 3 ) was used to discriminate cortical from trabecular compartment (8). Mechanical properties were obtained using the BIT software.…”

Effects of a 20-week high-intensity strength and sprint training program on tibial bone structure and strength in middle-aged and older male sprint athletes: a randomized controlled trial

“…A previous meta-analysis [13] found no significant exercise effects on bone strength, which may partly be explained by the short duration and inadequate power of the few published trials, along with the use of non-athletic study populations and less intensive training programs. Since then, studies on middle-aged and older people have found positive, site-specific effects on proximal femoral bone mass after impact training [14] but no effects on mid-femoral or mid-tibial structure and strength after strength training or combined strength and impact training [15,16]. To date, no attempts have been made to investigate the effects of intensive strength, sprint and plyometric training on bone in older athletes.…”

Vertical Jump Test as a Health-Promotion Screening Tool for Predicting Bone Strength in Young Adults

“…The researchers found a significant increase in cortical bone mineral content (BMC) in the exercise leg compared to the control leg. Not only did they find that the odd-loading impact exercise increased overall cortical mass surface density, cortical density, and endocortical trabecular density, they also found that there were substantially larger increases in the exercise leg at specific regions important in structural integrity of the proximal femur (Allison et al, 2015). These findings demonstrate the positive localized and overall changes in bone strength resulting from an odd-loading exercise of great enough magnitude and short enough duration, described by Turner (1998) as being necessary for bone adaptation.…”

“…During a 12-month randomized controlled trial of a unilateral hopping exercise intervention in healthy older men (ages 65-80), Allison et al (2015) studied the effect of high-impact, odd-loading, osteogenic exercise on cortical and trabecular bone mass at the proximal femur. Study participants were assigned randomly an exercise leg (right or left), with the opposite leg serving as the control, and they completed a single-leg hopping intervention.…”