Preventive Moderate Continuous Running-Exercise Conditioning Improves the Healing of Non-Critical Size Bone Defects in Male Wistar Rats: A Pilot Study Using µCT.

Céline Bourzac,Morad Bensidhoum,Nicolas Michoux,Christine Chappard,Mathieu Manassero,Stéphane Pallu,Hugues Portier

doi:10.3390/life10120308

Abstract

Although physical exercise has unquestionable benefits on bone health, its effects on bone healing have been poorly investigated. This study evaluated the effects of preemptive moderate continuous running on the healing of non-critical sized bone defects in rats by µCT. We hypothesized that a preemptive running exercise would quicken bone healing. Twenty 5-week-old, male, Wistar rats were randomly allocated to one of the following groups (n = 10): sedentary control (SED) or continuous running (EX, 45 min/d, 5 d/week at moderate speed, for 8 consecutive weeks). A 2 mm diameter bone defect was then performed in the right tibia and femur. No exercise was performed during a 4 week-convalescence. Healing-tissue trabecular microarchitectural parameters were assessed once a week for 4 weeks using µCT and plasma bone turnover markers measured at the end of the study protocol (time point T12). At T12, bone volume fraction (BV/TV; BV: bone volume, TV: tissue volume) of the healing tissue in tibiae and femurs from EX rats was higher compared to that in SED rats (p = 0.001). BV/TV in EX rats was also higher in tibiae than in femurs (p < 0.01). The bone mineral density of the healing tissue in femurs from EX rats was higher compared to that in femurs from SED rats (p < 0.03). N-terminal telopeptide of collagen type I in EX rats was decreased compared to SED rats (p < 0.05), while no differences were observed for alkaline phosphatase and parathyroid hormone. The study provides evidence that preemptive moderate continuous running improves the healing of non-critical sized bone defects in male Wistar rats.

Highlights

Physical exercise (PE) has unquestionable beneficial effects on bone health [1,2,3,4,5]
Moderate continuous running (MCR) on a treadmill, (i) increased the bone mineral density (BMD) in the tibiae or femora as a result of increased trabecular volume, number or thickness of trabeculae, (ii) decreased trabecular separation [6,9,10,11,12,13] and (iii) increased cortical bone volume in the tibiae [11], compared to respective results obtained in sedentary controls
We investigated whether exercise in the form of treadmill MCR prior to a bone injury can be a preemptive method that increases bone healing in a non-critical bone defect rat model

Summary

Introduction

Physical exercise (PE) has unquestionable beneficial effects on bone health [1,2,3,4,5]. Using rats as a model, the effects of different exercise modalities on bone biochemical characteristics and biomechanical properties have been previously investigated [6,7,8]. Some prophylactic effects of MCR on bone health were reported. MCR prevented trabecular bone loss related to hormone suppression in ovariectomized female [11] or castrated male [15] rats. MCR prevented decreased femoral BMD induced by age, most likely by limiting bone resorption [16]. Treadmill exercise prevented deterioration of subchondral bone in a rat model of osteoarthritis [17]

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