Resistance Exercise–induced Regulation of Muscle Protein Synthesis to Intraset Rest

• Published in: Medicine and science in sports and exercise Vol. 52; no. 5; pp. 1022 - 1030
• Main Authors: SALVADOR, AMADEO F., ASKOW, ANDREW T., MCKENNA, COLLEEN F., FANG, HSIN-YU, BURKE, SARAH K., LI, ZHONG, ULANOV, ALEXANDER V., PALUSKA, SCOTT A., PETRUZZELLO, STEVEN J., BOPPART, MARNI D., OLIVER, JONATHAN M., BURD, NICHOLAS A.
• Format: Journal Article
• Language: English
• Published: United States Lippincott Williams & Wilkins 01-05-2020; American College of Sports Medicine
• Subjects: Adaptor Proteins, Signal Transducing - biosynthesis; Amino Acids - blood; Blood Glucose - metabolism; Cross-Over Studies; Female; Humans; Insulin - blood; Lactic Acid - blood; Male; MAP Kinase Signaling System; Mechanistic Target of Rapamycin Complex 1 - biosynthesis; Muscle Proteins - biosynthesis; Myofibrils - metabolism; Perception - physiology; Phosphorylation; Physical Exertion - physiology; Resistance Training - methods; Rest; Transcription Factors - biosynthesis; Young Adult
• ISSN: 0195-9131; 1530-0315
• DOI: 10.1249/MSS.0000000000002213

During a traditional set configuration of resistance exercise (TRD), characterized by a continuous completion of repetitions, a decrease in power output tends to occur throughout a set of repetitions. Inclusion of intraset rest, otherwise known as a cluster set configuration (CLU), counteracts this power decline. However, the effect of a CLU configuration on postexercise myofibrillar protein synthesis rates (MPS) and anabolic signaling has not been investigated.
PURPOSEWe aimed to determine if any mechanistic differences exist between TRD and CLU signaling events associated with muscle anabolism.
METHODSIn randomized crossover trials, eight resistance-trained participants (23 ± 1 yr, 81 ± 4.7 kg, body fat18% ± 1.9%; 1 repetition maximum [1RM], 150 ± 9.1 kg) performed an acute bout of CLU (4 sets × (2 × 5) repetitions, 30-s intraset rest, 90-s interset rest) and TRD (4 sets × 10 repetitions, 120-s interset rest) barbell back squats at approximately 70% 1RM with total volume load equated during primed continuous L-[ring-C6]phenylalanine infusions. Blood and muscle biopsy samples were collected at rest and after exercise at 0, 2, and 5 h.
RESULTSThere was no difference in postexercise MPS between the CLU and TRD condition (P > 0.05) and no changes in phosphorylation of mTORC1 downstream targets (p70S6K and 4EBP1). Total and phosphorylated yes-associated protein on Ser127 transiently increased (P < 0.01) immediately after exercise (t = 0) in CLU (~2.1-fold) and TRD condition (~2.2-fold).
CONCLUSIONSOur results show that CLU is a viable anabolic option by preserving power output with similar MPS stimulation when compared with the TRD condition in trained young adults.