E T. Schroeder

Acute Response of PGC-1α and IGF-1 Isoforms to Maximal Eccentric Exercise in Skeletal Muscle of Postmenopausal Women.

Abstract Dieli-Conwright, CM, Kiwata, JL, Tuzon, C, Spektor, TM, Sattler, FR, Rice, JC, and Schroeder, ET. Acute response of PGC-1&agr; and IGF-1 isoforms to maximal eccentric exercise in skeletal muscle of postmenopausal women. J Strength Cond Res 30(4): 1161–1170, 2016—PGC-1&agr;4, a novel isoform of the transcriptional coactivator PGC-1&agr;, was recently postulated to modulate the expression of anabolic and catabolic genes and therefore regulate skeletal muscle hypertrophy. Resting levels of PGC-1&agr;4 messenger RNA (mRNA) expression were found to increase in healthy adults after resistance training. However, the acute effect of resistance exercise (RE) on PGC-1&agr;4 expression in populations prone to progressive muscle loss, such as postmenopausal women, has not been evaluated. Here, we investigated alterations in mRNA expression of PGC-1&agr;4 and PGC-1&agr;1, a regulator of muscle oxidative changes, in postmenopausal women after high-intensity eccentric RE and analyzed these findings with respect to changes in insulin-like growth factor (IGF)-1 and catabolic gene expression. Nine postmenopausal women (age, 57.9 ± 3.2 years) performed 10 sets of 10 maximal eccentric repetitions of single-leg extension with 20-second rest periods between sets. Muscle biopsies were obtained from the vastus lateralis of the exercised leg before and 4 hours after the RE bout with mRNA expression determined by quantitative real-time polymerase chain reaction. No significant changes in the mRNA expression of either PGC-1&agr; isoform were observed after acute eccentric RE (p > 0.05). IGF-1Ea mRNA expression significantly increased (p ⩽ 0.05), whereas IGF-1Eb and mechano-growth factor (MGF) did not significantly change (p > 0.05). PGC-1&agr;4 mRNA expression was associated with reduced mRNA expression of the catabolic gene myostatin (R = −0.88, p < 0.01), whereas MGF mRNA expression was associated with reduced mRNA expression of the catabolic gene FOXO3A (R = −0.81, p ⩽ 0.05). These data demonstrate an attenuated response of PGC-1&agr; isoforms to an acute bout of maximal eccentric exercise with short rest periods in postmenopausal women.

Abstract 988: Effect of a supervised exercise intervention on sarcopenic obesity and metabolic syndrome in prostate cancer patients: A randomized pilot study

Purpose: Prostate cancer survivors (PCS) on androgen deprivation therapy (ADT) experience adverse side effects such as skeletal muscle loss and adiposity gain, together called sarcopenic obesity, and changes in cardiometabolic factors that increase risk of metabolic syndrome (MetS). Resistance exercise can increase skeletal muscle mass, but no exercise interventions to date in PCS on ADT have concomitantly improved sarcopenic obesity and cardiometabolic risk factors. Utilizing a 12-week intervention of progressive resistance exercise designed to target skeletal muscle mass, this ongoing pilot trial investigates sarcopenic obesity and as a secondary analyses, MetS components, in PCS on ADT. Methods: Eighteen PCS (65.6±8.8 yr) on current or previous ADT were recruited from the USC Norris Comprehensive Cancer Center and randomized to resistance training (RT; n=9) or a control stretching program (CS; n=9). Body composition, measured through dual-x-ray absorptiometry, and MetS outcomes, including waist circumference, blood pressure, fasting blood glucose, triglycerides and HDL, were assessed at baseline and after the 12-week intervention. Appendicular skeletal muscle index (ASMI), a common index of sarcopenia, was calculated from body composition. RT performed a supervised total-body resistance exercise and stretching program 3 times/week. CS performed home-based stretching 3 times/week. Baseline differences were tested with univariate ANOVA. Differences in all outcomes were tested with 2(group) x 2(time) ANOVA. Results: No significant differences in ADT duration, Gleason score, body fat, skeletal muscle mass, or MetS components were found between groups at baseline (P>0.05). RT program compliance was 98.3%, while CS program compliance was 75.5%. Post-intervention, significant increases were observed in RT compared to CS for appendicular skeletal mass (mean±SE; 0.8±.4 kg; P=0.04) and ASMI (0.3±.1 kg/m2; P=0.041). A nonsignificant decrease in body fat (%) was observed in RT compared to CS (1.3±.7 %; P=.067; d=0.89). No differences were found in MetS components. Conclusions: While 12 weeks of resistance exercise in PCS on ADT improved skeletal muscle mass, no changes in adiposity and MetS variables were observed. Future interventions are needed for PCS to determine the optimal exercise prescription to target both sarcopenic obesity and cardiometabolic risk factors. Citation Format: Jacqueline L. Kiwata, Tanya B. Dorff, E. T. Schroeder, Christina M. Dieli-Conwright. Effect of a supervised exercise intervention on sarcopenic obesity and metabolic syndrome in prostate cancer patients: A randomized pilot study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 988. doi:10.1158/1538-7445.AM2017-988