Myogenic and proteolytic mRNA expression following blood flow restricted exercise

• Published in: Acta Physiologica 2011-02, Vol.201 (2), p.255-263
• Main Authors: Manini, T.M, Vincent, K.R, Leeuwenburgh, C.L, Lees, H.A, Kavazis, A.N, Borst, S.E, Clark, B.C
• Format: Article
• Language: English
• Subjects: Adult; Biological and medical sciences; Biopsy; blood flow restriction; Blood pressure; Data processing; Electromyography; Female; FOXO3 protein; Fundamental and applied biological sciences. Psychology; Gene expression; Humans; Hypertrophy; Insulin-like growth factor I; KAATSU; Knee; Male; mRNA; muscle; Muscle Development; Muscle Proteins - biosynthesis; Muscles; MyoD protein; myogenin; myostatin; Physical training; Polymerase chain reaction; Protein biosynthesis; Proteolysis; Quadriceps Muscle - blood supply; Quadriceps Muscle - growth & development; Quadriceps Muscle - metabolism; Regional Blood Flow; Repetition; Resistance Training; RNA, Messenger - metabolism; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Young Adult
• ISSN: 1748-1708; 1748-1716
• DOI: 10.1111/j.1748-1716.2010.02172.x

Aim: Resistance exercise performed at low loads (20-30% of maximal strength) with blood flow restriction (BFR) acutely increases protein synthesis and induces hypertrophy when performed chronically. We investigated myogenic and proteolytic mRNA expression 8 h following an acute bout of knee extension exercise. Methods: Fifteen subjects (22.8 ± 3.7 years, eight men and seven women) were randomized to two exercise conditions: BFR or control exercise. All participants performed four sets of exercise (30, 15, 15 and 15 repetitions) at 20% of maximal strength. Persons in the BFR group had a cuff placed on the upper thigh inflated to 1.5 times brachial systolic blood pressure (cuff pressure range: 135-186 mmHg). Muscle biopsies from the vastus lateralis were excised 24 h before and 8 h following the exercise. Results: RT-PCR analysis demonstrated no change in myogenic gene expression (insulin-like growth factor-1, MyoD, myogenin, myostatin - a negative regulator) with either exercise condition (P > 0.123). However, BFR exercise downregulated mRNA expression in transcripts associated with proteolytic pathways (FOXO3A, Atrogin-1 and MuRF-1) with no change in the control exercise condition. Specifically, median mRNA expression of FOXO3A decreased by 1.92-fold (P = 0.01), Atrogin-1 by 2.10-fold (P = 0.01) and MuRF-1 by 2.44-fold (P = 0.01). Conclusion: These data are consistent with the downregulation of proteolytic transcripts observed following high-load resistance exercise. In summary, myogenic genes are unchanged and proteolytic genes associated with muscle remodelling are reduced 8 h following low-load BFR exercise.