Summary of an article looking at an anabolic signaling response to morning (AM) and afternoon (PM) resistance training bout (80% RM).
24 physically active healthy males who did not perfrom resistance training regularly during the last 6 months (UK).
Intervention study (non-randomized).
Strength training group
- 40 minutes (AM session around 8am and PM session around 6pm separated by at least by 72 hours)
- exercises: seated leg press, chest press, lat pull down, shoulder press
- 50% 1RM for 2 sets 10 repetitions, 80% 1RM for 3 sets 10 repetitions (2 minutes rest between sets)
- 40 minutes
- of rest
acute anabolic signaling markers: IGFBP-3 (insulin-like growth factor-binding protein-3), myogenic index
cortisol (blood sample)
temperature (infrared ear thermometer)
serum samples were treated on C2C12 mice cell lines
IGFBP-3 – a protein that binds insulin-like growth factor IGF-1, which has an anabolic effect.
cortisol – a hormone that among other functions increases muscle breakdown.
myogenic index – a measure of cells acquiring specialization.
Body temperature was higher pre-exercise at PM (37.3°C) than at AM (36.9°C)
Pre- and post-exercise cortisol concentration was lower at PM than AM in both groups.
Myogenic index was higher (114%) pre-exercise at PM than at AM, but post-exercise myogenic index was higher at AM than PM.
Serum IGFBP-3 increased significantly after PM exercise when compared with decrease after AM exercise. No differences were observed in non-exercising group.
Post-exercise lactate was higher at PM (6.4mmol/L) than AM (5.8mmol/L)
Pre-exercise myotube width was greater at PM compared to AM. No difference in myotube width between groups post-exercise.
No difference in pre-exercise serum, glucose level or haematocrit at AM compared to PM
Haematocrit and serum changed from pre- to post-exercie both AM and PM.
Take home message
Burley SD, Whittingham-Dowd J, Allen J, Grosset JF, Onambele-Pearson GL. The differential hormonal milieu of morning versus evening may have an impact on muscle hypertrophic potential. PLoS One. 2016 Sep 1;11(9):e0161500.