Journal Article

Dissociation of Increases in PGC-1α and Its Regulators from Exercise Intensity and Muscle Activation Following Acute Exercise

Foster, William S., Graham, Ryan B., Little, Jonathan P., Gurd, Brendon J., Simpson, Craig A., Edgett, Brittany A., Hankinson, Paul B.

2013

Overview

Muscle activation as well as changes in peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) following high-intensity interval exercise (HIIE) were examined in young healthy men (n  = 8; age, 21.9±2.2 yrs; VO2peak, 53.1±6.4 ml/min/kg; peak work rate, 317±23.5 watts). On each of 3 visits HIIE was performed on a cycle ergometer at a target intensity of 73, 100, or 133% of peak work rate. Muscle biopsies were taken at rest and three hours after each exercise condition. Total work was not different between conditions (∼730 kJ) while average power output (73%, 237±21; 100%, 323±26; 133%, 384±35 watts) and EMG derived muscle activation (73%, 1262±605; 100%, 2089±737; 133%, 3029±1206 total integrated EMG per interval) increased in an intensity dependent fashion. PGC-1α mRNA was elevated after all three conditions (p<0.05), with a greater increase observed following the 100% condition (∼9 fold, p<0.05) compared to both the 73 and 133% conditions (∼4 fold). When expressed relative to muscle activation, the increase in PGC-1α mRNA for the 133% condition was less than that for the 73 and 100% conditions (p<0.05). SIRT1 mRNA was also elevated after all three conditions (∼1.4 fold, p<0.05), with no difference between conditions. These findings suggest that intensity-dependent increases in PGC-1α mRNA following submaximal exercise are largely due to increases in muscle recruitment. As well, the blunted response of PGC-1α mRNA expression following supramaximal exercise may indicate that signalling mediated activation of PGC-1α may also be blunted. We also indentify that increases in PDK4, SIRT1, and RIP140 mRNA following acute exercise are dissociated from exercise intensity and muscle activation, while increases in EGR1 are augmented with supramaximal HIIE (p<0.05).

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Activation / Adult / Biology / Biopsy / Biosynthesis / Dissociation / Early Growth Response Protein 1 - genetics / Early Growth Response Protein 1 - metabolism / EGR-1 protein / Electromyography / EMG / Exercise - physiology / Exercise intensity / Fitness training programs / Gene Expression / Humans / Kinesiology / Male / Medicine / Muscle contraction / Muscle, Skeletal - physiology / Muscles / Musculoskeletal system / Oxygen Consumption / Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha / Protein-Serine-Threonine Kinases - genetics / Protein-Serine-Threonine Kinases - metabolism / Recruitment / Regulators / RNA, Messenger - genetics / RNA, Messenger - metabolism / Rodents / Signal transduction / Signaling / SIRT1 protein / Sirtuin 1 - genetics / Sirtuin 1 - metabolism / Studies / Transcription Factors - genetics / Transcription Factors - metabolism / Tumor Suppressor Protein p53 - genetics / Tumor Suppressor Protein p53 - metabolism / Young Adult