Acute and Chronic Effects of Traditional and Blood Flow Restricted Resistance Exercise on Bone Markers

Abstract

The adaptive mechanisms underlying the well described effect of low-intensity resistance exercise (RE) with blood flow restriction (BFR) to increase muscle strength and muscle mass in humans are not fully understood. Although the influence of Akt/mTOR signalling and a stimulating effect on protein synthesis have been demonstrated, the potential role of myogenic satellite cell activation has not been examined. In the present study BFR RE was hypothesized to activate myogenic satellite cells (SC) expressing Pax-7. PURPOSE:To examine the effect of short-term low-intensity RE with BFR on the activation of Pax7 + SC in relation to muscle cell growth and myonuclei distribution.METHODS: 10 young men (23 ±2 yrs) completed 7 sessions of BFR knee extensor resistance exercise (20% 1-RM load) in 5 days. Training consisted of 4 sets of isolated knee extensor contractions (20% 1-RM loads) to concentric failure during concurrent blood flow restriction (100 mmHg cuff pressure). Muscle biopsies were obtained (VL) at baseline (pre) and day 8 (post 2 days resting). SC expressing Pax-7, myonuclei density and muscle fiber area were assessed by immunohistochemistry.