Low-intensity Walk Training With Blood-Flow Reduction Concurrently Improved VO2peak and Muscular Function In Elderly Women

Abstract

Low-intensity walk training with leg blood flow reduction (BFR-walk) has been shown to elicit a significant increase in skeletal muscle size and strength, and may also improve in aerobic capacity in young subjects. However, it is unknown if BFR-walk training would improve muscular function/ hypertrophy and aerobic capacity in older subjects. PURPOSE: To investigate the effects of BFR-walk training on MRI-measured muscle size and function as well as peak oxygen uptake (VO2peak) in the elderly women. METHODS: 18 elderly women (age, 65.7±4.3 yrs; BMI, 22.8±2.8 kg/m2) were divided into two walk training groups: BFR-walk (n=10) and control walk (n=8, CON-walk). Both groups performed 20 min treadmill walking at an exercise intensity of 45% of heart rate reserve, 4 days per week for 10 weeks. The BFR-walk group wore pressure cuff belts (5 cm wide) on the proximal part of both upper legs during training (external compression: 160-200 mmHg). MRI-measured mid-thigh muscle cross-sectional area (CSA), and also maximal isometric and isokinetic (30 and 180 deg/sec) knee extension and flexion strength (Biodex system-3) were measured before and after training. VO2peak was estimated by fitting age-predicted maximum heart rate (HRmax) value into a linear regression equation computed from the individual VO2 and HR values obtained during a graded cycle exercise test (until ∼80% HRmax). Functional ability was assessed by the Timed Up and Go test (time to walk both ways from the chair to 2.4m marker, UG-Test) and the Chair Stand test (repeated chair stand in 30 seconds, CS-Test). RESULTS: Maximum isometric (6%) and isokinetic (3∼22%) strength and thigh muscle CSA (3.3%) increased in the BFR-walk group, but not in the CON-walk group. VO2peak also increased (P<0.05), but only in the BFR-walk group (pre, 25.0±4.0; post, 27.5±5.2 ml/kg/min), however, there was a trend for improvement in the CON-walk group (pre, 26.3±3.1; post, 29.1±3.9 ml/kg/min). Similarly, functional ability improved (P<0.01) only in the BFR-walk group (10.7% for UG-Test, 20.5% for CS-Test). CONCLUSION: Our results suggest that 40-50% intensity BFR-walk training improves both muscle hypertrophy and aerobic capacity concurrently in the elderly. The improvements of functional ability were probably due in part to the increases in muscular function.