I am behind on some cool research, so I have jammed a bunch into one long post. Be sure to look towards the end for a new study on protein and carb timing while in a FED state (translation-more applicable to the standard athlete since most are not fasting).
Here we go!
Vps34 is activated following high resistance contraction.
Mackenzie MG, Hamilton DL, Murray JT, Taylor PM, Baar K.
University of Dundee. Following resistance exercise in the fasted state, both protein synthesis and degradation in skeletal muscle are increased. The addition of essential amino acids potentiates the synthetic response suggesting that an amino acid sensor, which is involved in both synthesis and degradation, may be activated by resistance exercise. One such candidate protein is the class 3 phosphatidylinositol 3OH -kinase (PI3K) Vps34. To determine whether mammalian Vps34 (mVps34) is modulated by high resistance contractions, mVps34 and S6K1 (an index of mTORC1) activity were measured in the distal hindlimb muscles of rats 0.5, 3, 6, and 18 hours after acute unilateral high resistance contractions with the contralateral muscles serving as a control.
In the lengthening tibialis anterior (TA) muscle, S6K1 (0.5h=366.3+/-112.08%, 3h=124.7+/-15.96%, and 6h=129.2+/-0%) and mVps34 (3h=68.8+/-15.1% and 6h=36.0+/-8.79%) activity both increased, whereas in the shortening soleus and plantaris (PLN) muscles the increase was significantly lower (PLN S6K1 0.5h=33.1+/-2.29% and 3h=47.0+/-6.65%; mVps34 3h=24.5+/-7.92%). HPLC analysis of the TA demonstrated a 25% increase in intramuscular leucine concentration in rats 1.5 hours after exercise. A similar level of leucine added to C2C12 cells in vitro increased mVps34 activity 3.2-fold.
Conclusion: These data suggest that, following high resistance contractions, mammalian Vps34 activity is stimulated by an influx of essential amino acids such as leucine and this may prolong mTORC1 signalling and contribute to muscle hypertrophy.
My notes: More data that protein around training time is a good thing!
Voluntary Wheel Running Initially Increases Adrenal Sensitivity to Adrenocorticotrophic Hormone, which is Attenuated with Long-term Training.
Campbell JE, Rakhshani N, Fediuc S, Bruni S, Riddell MC.
York University. Although exercise is a common and potent activator of the hypothalamic-pituitary adrenal (HPA) axis, the effects of exercise on the acute stress response are not well understood. Here, we investigated the effects of short (2wk)- and long-term (8wk) voluntary wheel running on adrenal sensitivity to ACTH stimulation and the acute stress response to restraint in male rats. Diurnal glucocorticoid (GC) patterns were measured on days 7 (all groups) and 35 (8 wk groups). Rats were subjected to 20 minutes of restraint stress on either week 1 or on week 7 of treatment to assess HPA activation. One week later, exogenous ACTH (75 ng/kg) was administered to assess adrenal sensitivity to ACTH. Following this, adrenals were collected and analyzed for key proteins involved in corticosterone (CORT) synthesis.
By the end of week one, exercising (E) animals had a 2-fold higher peak diurnal CORT levels compared with sedentary (S) animals (p
Concluison: These results show that volitional wheel running initially causes hyperactivation of the hypothalamic-pituitary adrenal -axis, due to enhanced adrenal sensitivity to ACTH, but that these alterations in hypothalamic-pituitary adrenal activity are completely restored by 8 weeks of training.
My notes: Very cool study that shows ACUTE (short lived) effects may not (and normally do not) hang around when viewed over a longer time frame.
Also note, this was VOLUNTARY wheel running and the results may be different if they force the little buggers to run on the wheel. Higher stress = even higher cortisol.
Age-related differences in dose response of muscle protein synthesis to resistance exercise in young and old men.
Kumar V, Selby A, Rankin D, Patel R, Atherton P, Hildebrandt W, Williams J, Smith K, Seynnes O, Hiscock N, Rennie MJ.
University of Nottingham, School of Graduate Entry Medicine and Health, Derby, DE22 3DT. We investigated how myofibrillar protein synthesis and muscle anabolic signalling were affected by resistance exercise at 20-90% of 1 repetition maximum (1 RM) in two groups of 25 each, postabsorptive, healthy, young (24+/-6 y) and old (70+/-5 y) men with identical body mass indices (24+/-2 kg.m(-2)). We hypothesized that, in response to exercise, anabolic signalling molecule phosphorylation and MPS would be modified in a dose-dependant fashion, but to a lesser extent in older men. Vastus lateralis muscle was sampled before, immediately after, and 1, 2 and 4 h post-exercise. MPS was measured by incorporation of [1,2-(13)C]leucine (gas chromatography-combustion-mass spectrometry using plasma [1,2-(13)C]alpha-ketoisocaparoate as surrogate precursor); the phosphorylation of p70 ribosomal S6 kinase (p70s6K) and eukaryotic initiation factor 4E binding protein 1(4EBP1) was measured using Western analysis with anti-phosphoantibodies.
In each group, there was a sigmoidal dose-response relationship between MPS at 1-2 h post-exercise and exercise intensity, which was blunted (P
Conclusion: The results suggest that in the postabsorptive state (i) muscle protein synthesis is dose-dependant on intensity rising to a plateau at 60-90% 1 repetition maximum; (ii) older men show anabolic resistance of signalling and muscle protein synthesis to resistance exercise.
My Notes: There are more and more data to suggest that the response of older adults to the same amount of protein is different. I talked about this briefly in a recent newsletter (sign up on the upper right of this blog) and this is another study helping that argument along.
Nutritional consideration in the aging athlete.
Tarnopolsky MA.
Department of Pediatrics, Faculty of Health Science, McMaster University, Hamilton, Ontario, Canada. tarnopol@mcmaster.ca OBJECTIVE:: To evaluate the evidence for dietary recommendations in older adult athletes. DESIGN:: Interpretive review of the literature.
RESULTS:: Regarding resistance training, a protein intake of slightly more than 0.8 g/kg/d is
required to optimize gains in muscle strength.
The early provision of protein and carbohydrate following a weight training session can enhance resultant strength and fat-free mass gains. Supplementation with creatine monohydrate (approximately 5 g/d) can potentiate some of the gains in strength and fat free mass attained through resistance exercise training. Regarding endurance exercise training, there are no studies evaluating carbohydrate loading, during-event, or postexercise carbohydrate/nutritional replacement in older adults.
CONCLUSIONS::
The amount and timing of dietary protein is important to maximize strength and gains in fat-free mass during resistance exercise training. Creatine monohydrate supplementation can potentiate some of these gains during the first 4 to 6 months of training.
Older adults should consume adequate carbohydrates during endurance training (6-8 g/kg/d) and may benefit from the provision of carbohydrate and protein in the early recovery phase following endurance exercise to maximize glycogen re-synthesis for a subsequent exercise bout.
There is no scientific reason to assume that older athletes will respond differently to the pre- and during-race fluid and carbohydrate replacement strategies suggested for younger athletes.
My Notes: Note that the last few lines in the conclusion take about ENDURANCE training not strength training! Creatine is good—word!
Coingestion of carbohydrate and protein hydrolysate stimulates muscle protein synthesis during exercise in young men, with no further increase during subsequent overnight recovery.
Beelen M, Tieland M, Gijsen AP, Vandereyt H, Kies AK, Kuipers H, Saris WH, Koopman R, van Loon LJ.
Department of Movement Sciences, Nutrition and Toxicology Research Institute Maastricht, Maastricht University, 6200 MD Maastricht, The Netherlands. milou.beelen@bw.unimaas.nl We investigated the effect of carbohydrate and protein hydrolysate ingestion on whole-body and muscle protein synthesis during a combined endurance and resistance exercise session and subsequent overnight recovery. Twenty healthy men were studied in the evening after consuming a standardized diet throughout the day. Subjects participated in a 2-h exercise session during which beverages containing both carbohydrate (0.15 g x kg(-1) x h(-1)) and a protein hydrolysate (0.15 g x kg(-1) x h(-1)) (C+P, n = 10) or water only (W, n = 10) were ingested. Participants consumed 2 additional beverages during early recovery and remained overnight at the hospital.
Continuous i.v. infusions with L-[ring-(13)C(6)]-phenylalanine and L-[ring-(2)H(2)]-tyrosine were applied and blood and muscle samples were collected to assess whole-body and muscle protein synthesis rates. During exercise, whole-body and muscle protein synthesis rates increased by 29 and 48% with protein and carbohydrate coingestion (P
Conclusion: We conclude that, even in a fed state, protein and carbohydrate supplementation stimulates muscle protein synthesis during exercise. Ingestion of protein with carbohydrate during and immediately after exercise improves whole-body protein synthesis but does not further augment muscle protein synthesis rates during 9 h of subsequent overnight recovery.
My Notes: Most studies of this type are done on fasting subjects, so it is cool to see more work done on subjects in a fed (they ate recently) state as this is more applicable to most athletes.
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