Most U.S. adults do not meet minimum exercise recommendations by ACSM. We and others have shown an increase in GLUT4 protein and glucose uptake with electrical stimulation induced muscle contraction using an in vitro cell culture model. However, effectiveness of neuromuscular electrical stimulation (NMES) in humans to improve insulin sensitivity is not clear.
Purpose: To determine the effects of four weeks of NMES on insulin sensitivity, substrate utilization, and muscle mass in sedentary humans.
Methods: Sedentary overweight/obese subjects (n=10; Age 36.8 ±3.8 yrs; BMI 32.0 ±1.3 kg/m2) were randomized into a control (Con) or NMES group. All participants received bilateral quadriceps stimulation (3x/wk; 30 min/ses) either at low intensity sensory level (Con) or high intensity neuromuscular level (NMES) for 4 weeks (50Hz). Insulin sensitivity was assessed by oral glucose tolerance test (OGTT), substrate utilization by indirect calorimetry, blood lactate by lactate analyzer, and body composition by DXA.
Results: Con and NMES groups had comparable fasting blood glucose, glucose tolerance, substrate utilization, and muscle mass (all p>0.05) at baseline. Four weeks of NMES tended to improve glucose tolerance, measured by glucose area under the curve (AUC) (455.6 ±26.1 to 415.4 ±25.9 AU; p=0.07) whereas no change was observed in Con (430.7 ±20.2 to 494.7 ±77.2 AU; p=0.76). Glucose level after 2 hours of glucose consumption during OGTT was significantly lower after 4 weeks of NMES (150.9 ±7.6 to 138.2 ±7.6 mg/dL; p=0.03) whereas no change was observed in Con (151.8 ±6.1 to 173.2 ±34.2 mg/dL; p=0.33).Additionally, lactate AUC assessed during 30 min of NMES, was significantly greater compared to that of Con (p<0.02). There was no change in substrate utilization (p=0.85) or muscle mass (p=0.17) after NMES intervention.
Conclusion: NMES is a novel and effective strategy to improve insulin sensitivity and glucose utilization in an at-risk overweight/obese sedentary population.
S. Bajpeyi: None. M. Galvan: None. M.J. Sanchez: None. J.B. Boyle: None. K. Min: None. F.J. Agullo: None. J.D. Covington: None.
University of Texas at El Paso