Myogenic and proteolytic mRNA expression following blood flow restricted exercise.
OBJECTIVE
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).


CONCLUSIONS
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.
Manini
T M
TM
Department of Aging and Geriatric Research, University of Florida, Gainesville, FL 32611-0107, USA. tmanini@aging.ufl.edu
Vincent
K R
KR
Leeuwenburgh
C L
CL
Lees
H A
HA
Kavazis
A N
AN
Borst
S E
SE
Clark
B C
BC
D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D006984:Hypertrophy; D008297:Male; D024510:Muscle Development; D009124:Muscle Proteins / Q000096:biosynthesis*; D052097:Quadriceps Muscle / Q000098:blood supply / Q000254:growth & development / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012039:Regional Blood Flow; D055070:Resistance Training; D055815:Young Adult
D009124:Muscle Proteins; D012333:RNA, Messenger