Resistance exercise reduces intramuscular substrate stores through activation of ERK1/2 in obese women

Abstract

The negative association between intramuscular triglycerides (IMTG) and metabolic health highlights the importance of characterizing interventions that effectively lower muscular substrate stores. The purpose of this study was to evaluate the influence of acute resistance exercise (RE) on IMTG and glycogen content in obese women. Six women with high percent body fat (age 29±3 yr; BMI 28±3 kg/m2, body fat 38±4%) performed 6 sets of 10 repetitions of knee extension exercise at 70% 1RM. Muscle biopsies were obtained from the vastus lateralis before, 1 min after (POST1), and 2h after (POST2) exercise. Muscle glycogen and IMTG content were measured biochemically and western blotting techniques were used to assess activation of ERK1/2 and AMPKα. Acute RE reduced (P<0.05) muscle glycogen ~25% at POST1 and remained lower at POST2 (317±14; 241±30; 235±26 mmol/kg/dry wt). IMTG content was also significantly reduced (P<0.05) at POST1 and POST2 (75±5; 45±6; 50±10 mmol/kg/dry wt). ERK1/2 phosphorylation was increased (P<0.05) ~3-fold at POST1 and POST2. However, AMPKα phosphorylation was unchanged in response to RE. In conclusion, acute RE is an effective intervention to lower IMTG content in obese women. Furthermore, IMTG use during RE in obese women appears to be independent of AMPKα signaling.