Effects of high-volume and high-intensity resistance training on skeletal muscle ultrastructure

Abstract

Background: Recently there has been enthusiasm surrounding the differential training adaptations that result from higher-load (HL) versus higher-volume (HV) resistance training. The purpose of this study was to evaluate the effects of HL versus HV training on markers of skeletal muscle hypertrophy and strength as well as a broad spectrum of molecular markers obtained from skeletal muscle biopsies. Methods: Trained college-age males (n=15, age: 23±3 years old; training age: 7±3 years; squat 1RM relative to body mass: 1.9) performed unilateral lower body training three days per week over 6 weeks, with one leg being randomly assigned to HV training and the other to HL training. Vastus lateralis (VL) biopsies were obtained prior to the start of the study (PRE), 72 hours following the last exercise bout (POST), and following 10 days of passive recovery (POSTDL). Body composition and strength tests were also performed at each testing session, and various biochemical assays were performed on muscle tissue. RESULTS: Condition×time interactions were observed for unilateral leg extension 1RM (HL>HV at POST and POSTDL) and VL muscle cross-sectional area (post hoc tests indicated no significance between conditions over time). A main effect of condition was observed for unilateral leg extension 1RM (HL>HV) and sarcoplasmic protein concentrations (HV>HL). A main effect of time was observed for unilateral leg press 1RM (PRE<POST and POSTDL), unilateral leg extension 1RM (PRE<POST<POSTDL), knee extensor peak torque at 60°/sec (PRE and POST<POSTDL), dual-energy x-ray absorptiometry (DXA)-derived upper leg total and lean mass values (PRE<POST and POSTDL), ultrasound-derived VL thickness (PRE and POSTDL<POST), sarcoplasmic protein concentrations (POST and POSTDL<PRE), and tropomyosin and troponin protein abundances (PRE>POST and POSTDL). CONCLUSION: In summary, our data suggest that short-term HV and HL training elicit similar hypertrophic, strength, and molecular adaptations.