Effects of a 3-month weight-bearing and resistance exercise training on circulating osteogenic cells and bone formation markers in postmenopausal women with low bone mass.

Osteoporosis is a health issue in postmenopausal women. Physical activity is recommended in these subjects, since it has positive effects on bone mass. Cellular mechanisms underlying this effect are still unclear. Osteogenic cells, released after physical exertion, could be a key factor in exercise-induced bone formation. INTRODUCTION: The aim of our research was to explore if a weight-bearing and resistance exercise program could positively affect circulating osteogenic cells (OCs), markers of bone formation and quality of life (QoL) in osteopenic postmenopausal women. METHODS: We recruited 33 postmenopausal women with a T-score at lumbar spine or femoral neck between - 1 and - 2.5 SD. Anthropometric and fitness parameters, bone-remodeling markers, OCs, and QoL were evaluated at the time of enrolment, after 1-month run-in period, and after 3 months of weight-bearing and resistance exercise. RESULTS: After 3 months of training, the pro-collagen type 1 N-terminal peptide (P1NP) and the number of OCs were significantly increased, with no significant increase of the type 1 collagen cross-linked C-telopeptide (sCTX). We also observed a significant increase in body height, one-repetition maximum (1RM) on the pull-down lat machine and leg press, and mean VO2max. The increase of immature circulating OCs was significantly correlated with the improvement of 1RM both of the upper and lower limbs. Moreover, QoL was significantly improved with regard to pain, physical function, mental function, and general QoL. The improvement in QoL, namely in the overall score and in the pain score, was significantly correlated with the increase in height. CONCLUSIONS: The exercise program we trialed is able to increase the markers of bone formation and the commitment of immature OCs with no significant increase in the markers of bone resorption. Our results confirm that combined weight-bearing and resistance physical activity is an effective tool to improve QoL of postmenopausal women with low bone mass. TRIAL REGISTRATION: NCT03195517.

Femoral neck bone adaptation to weight-bearing physical activity by computational analysis.

Individual differences in bone mass distribution at the proximal femur may be determined by daily weight-bearing physical activity (PA) since bone self-adapts according to the mechanical loads that is submitted. The aim of this study was to analyse computationally the effect of different weight-bearing PA types in the adaptation of the femoral neck (FN) by analysing regional differences in bone mineral density (BMD) at the integral FN and its superior, inferior, anterior and posterior subregions. To achieve this, it was adopted a 3-D femoral finite element (FE) model coupled with a suitable bone remodeling model. Different PA types were determined based both on ordinary lifestyle and mechanically more demanding PA as low magnitude impacts (L-I), moderate-magnitude impacts from odd directions (O-I) and high-magnitude vertical impacts (H-I). It was observed that as time spent in weight-bearing PA increases, BMD augment around the integral FN, but with different bone mass gain rates between subregions depending on the magnitude and directions of the hip contact forces; H-I was the type of weight-bearing PA which structurally most favor the gain of bone mass superiorly at the FN while both the H-I and the O-I types of PA promoted the largest bone mass gain rates at the anterior and posterior subregions of the FN. Because these types of weight-bearing PA were associated with a more uniform bone mass spatial distribution at the FN, they should provide a potential basis for targeted PA-based intervention programs for improving hip strength.