Abstract
We determined myofibrillar and mitochondrial protein fractional synthesis rates (FSR), intramuscular signaling protein phosphorylation, and mRNA expression responses after isolated bouts of resistance exercise (RE), aerobic exercise (AE), or in combination [termed concurrent exercise (CE)] in sedentary middle-aged men. Eight subjects (age 53.3 1.8 yr;
body mass index 29.4 1.4 kg·m2) randomly completed 8 8 leg
extension repetitions at 70% of one repetition-maximum, 40 min of
cycling at 55% peak aerobic power output (AE), or (consecutively)
50% of the RE and AE trials (CE). Biopsies were obtained (during a
primed, constant infusion of L-[ring-13C6]phenylalanine) while fasted,
and at 1 and 4 h following postexercise ingestion of 20 g of protein.
All trials increased mitochondrial FSR above fasted rates (RE
1.3-fold; AE 1.5; CE 1.4; P 0.05), although only CE (2.2) and
RE (1.8) increased myofibrillar FSR (P 0.05). At 1 h postexercise,
phosphorylation of Akt on Ser473 (CE 7.7; RE 4.6) and Thr308
(CE 4.4; RE 2.9), and PRAS40 on Thr246 (CE 3.8; AE 2.5)
increased (P 0.05), with CE greater than AE for Akt Ser473-Thr308
and greater than RE for PRAS40 (P 0.05). Despite increased
phosphorylation of Akt-PRAS40, phosphorylation of mammalian target
of rapamycin (Ser2448) remained unchanged (P 0.05), while
rpS6 (Ser235/236) increased only in RE (10.4) (P 0.05). CE and AE
both resulted in increased peroxisome proliferator receptor- coactivator
1- (PGC1 ) expression at 1 h (CE 2.9; AE 2.8; P 0.05) and 4
h (CE 2.6; AE 2.4) and PGC1 expression at 4 h (CE 2.1; AE
2.6; P 0.05). These data suggest that CE-induced acute stimulation of
myofibrillar and mitochondrial FSR, protein signaling, and mRNA expression are equivalent to either isolate mode (RE or AE). These results
occurred without an interference effect on muscle protein subfractional
synthesis rates, protein signaling, or mRNA expression.
body mass index 29.4 1.4 kg·m2) randomly completed 8 8 leg
extension repetitions at 70% of one repetition-maximum, 40 min of
cycling at 55% peak aerobic power output (AE), or (consecutively)
50% of the RE and AE trials (CE). Biopsies were obtained (during a
primed, constant infusion of L-[ring-13C6]phenylalanine) while fasted,
and at 1 and 4 h following postexercise ingestion of 20 g of protein.
All trials increased mitochondrial FSR above fasted rates (RE
1.3-fold; AE 1.5; CE 1.4; P 0.05), although only CE (2.2) and
RE (1.8) increased myofibrillar FSR (P 0.05). At 1 h postexercise,
phosphorylation of Akt on Ser473 (CE 7.7; RE 4.6) and Thr308
(CE 4.4; RE 2.9), and PRAS40 on Thr246 (CE 3.8; AE 2.5)
increased (P 0.05), with CE greater than AE for Akt Ser473-Thr308
and greater than RE for PRAS40 (P 0.05). Despite increased
phosphorylation of Akt-PRAS40, phosphorylation of mammalian target
of rapamycin (Ser2448) remained unchanged (P 0.05), while
rpS6 (Ser235/236) increased only in RE (10.4) (P 0.05). CE and AE
both resulted in increased peroxisome proliferator receptor- coactivator
1- (PGC1 ) expression at 1 h (CE 2.9; AE 2.8; P 0.05) and 4
h (CE 2.6; AE 2.4) and PGC1 expression at 4 h (CE 2.1; AE
2.6; P 0.05). These data suggest that CE-induced acute stimulation of
myofibrillar and mitochondrial FSR, protein signaling, and mRNA expression are equivalent to either isolate mode (RE or AE). These results
occurred without an interference effect on muscle protein subfractional
synthesis rates, protein signaling, or mRNA expression.
| Original language | English |
|---|---|
| Pages (from-to) | 1992-2001 |
| Number of pages | 10 |
| Journal | Journal of Applied Physiology |
| Volume | 112 |
| Issue number | 12 |
| Early online date | 5 Apr 2012 |
| DOIs | |
| Publication status | Published - 15 Jun 2012 |
| Externally published | Yes |
Keywords
- untrained adults
- muscle protein synthesis
- anabolic protein signaling
- gene expression