Exercise training augments regional bone and marrow blood flow during exercise

Abstract

Introduction: The principal nutrient artery to the femur demonstrates an increase in nitric oxide-mediated vasodilation in rats after treadmill exercise training. The present study sought to determine whether exercise training improves hindlimb bone and marrow blood flow distribution at rest and during exercise.

Methods: Six 8-month old male Sprague-Dawley rats were exercise trained (ET) with treadmill walking at 15 m · min(-1) up a 15° incline for 60 min · d(-1) over a 10- to 12-wk period. Sedentary (SED) control animals were acclimated to treadmill exercise for 5 min · d(-1) during the week preceding the blood flow measurements. Blood flow to nine distinct regions of the femur, tibia, and fibula was determined at rest and during low-intensity exercise (15 m · min(-1) walking, 0° incline) using the reference sample microsphere method.

Results: The results demonstrate an augmentation of exercise hyperemia above that observed in SED rats during exercise in only one region of the bone, the femoral diaphysis, of ET rats. However, whereas exercise hyperemia occurred in three of the nine hindlimb bone regions measured in SED rats, exercise hyperemia occurred in seven of nine regions in ET rats.

Conclusions: These data indicate an increase in generalized hindlimb bone and marrow blood flow during physical activity after a period of exercise training. Elevations in regional bone and marrow blood flow after training may augment medullary pressure and bone interstitial fluid flow, thus benefiting bone integrity.

Conflict of interest statement

The authors have no conflicts of interest to declare. The results of the present study do not constitute endorsement by the American College of Sports Medicine.

Figures

Figure 1

Effects of acute exercise and chronic exercise training on regional bone and marrow blood flow (A) and vascular conductance (B) in the femur. Values are means ± SE. *Mean is different from sedentary (SED) resting mean (P†Mean is different from SED exercising mean (P<0.05).‡Mean is different from exercise trained (ET) resting mean (P<0.05).

Figure 2

Effects of acute exercise and chronic exercise training on regional bone and marrow blood flow (A) and vascular conductance (B) in the tibia. Values are means ± SE. *Mean is different from sedentary (SED) resting mean (Pβ (P<0.1). ‡Mean is different from exercise trained (ET) resting mean (P<0.05);α (P<0.1).

Figure 3

Effects of acute exercise and chronic exercise training on bone and marrow blood flow (A) and vascular conductance (B) in the fibula. Values are means ± SE. *Mean is different from sedentary (SED) resting mean (P†Mean is different from SED exercising mean (P<0.05).‡ Mean is different from exercise trained (ET) resting mean (P<0.05);α (P<0.1).