Vandre C. Figueiredo

Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training

Cold water immersion is a popular strategy to recover from exercise. However, whether regular cold water immersion influences muscle adaptations to strength training is not well understood. We compared the effects of cold water immersion and active recovery on changes in muscle mass and strength after 12 weeks of strength training. We also examined the effects of these two treatments on hypertrophy signalling pathways and satellite cell activity in skeletal muscle after acute strength exercise. Cold water immersion attenuated long term gains in muscle mass and strength. It also blunted the activation of key proteins and satellite cells in skeletal muscle up to 2 days after strength exercise. Individuals who use strength training to improve athletic performance, recover from injury or maintain their health should therefore reconsider whether to use cold water immersion as an adjuvant to their training.

Ribosome biogenesis adaptation in resistance training-induced human skeletal muscle hypertrophy

Resistance training (RT) has the capacity to increase skeletal muscle mass, which is due in part to transient increases in the rate of muscle protein synthesis during postexercise recovery. The role of ribosome biogenesis in supporting the increased muscle protein synthetic demands is not known. This study examined the effect of both a single acute bout of resistance exercise (RE) and a chronic RT program on the muscle ribosome biogenesis response. Fourteen healthy young men performed a single bout of RE both before and after 8 wk of chronic RT. Muscle cross-sectional area was increased by 6 ± 4.5% in response to 8 wk of RT. Acute RE-induced activation of the ERK and mTOR pathways were similar before and after RT, as assessed by phosphorylation of ERK, MNK1, p70S6K, and S6 ribosomal protein 1 h postexercise. Phosphorylation of TIF-IA was also similarly elevated following both RE sessions. Cyclin D1 protein levels, which appeared to be regulated at the translational rather than transcriptional level, were acutely increased after RE. UBF was the only protein found to be highly phosphorylated at rest after 8 wk of training. Also, muscle levels of the rRNAs, including the precursor 45S and the mature transcripts (28S, 18S, and 5.8S), were increased in response to RT. We propose that ribosome biogenesis is an important yet overlooked event in RE-induced muscle hypertrophy that warrants further investigation.

The effects of cold water immersion and active recovery on inflammation and cell stress responses in human skeletal muscle after resistance exercise

Cold water immersion and active recovery are common post‐exercise recovery treatments. A key assumption about the benefits of cold water immersion is that it reduces inflammation in skeletal muscle. However, no data are available from humans to support this notion. We compared the effects of cold water immersion and active recovery on inflammatory and cellular stress responses in skeletal muscle from exercise‐trained men 2, 24 and 48 h during recovery after acute resistance exercise. Exercise led to the infiltration of inflammatory cells, with increased mRNA expression of pro‐inflammatory cytokines and neurotrophins, and the subcellular translocation of heat shock proteins in muscle. These responses did not differ significantly between cold water immersion and active recovery. Our results suggest that cold water immersion is no more effective than active recovery for minimizing the inflammatory and stress responses in muscle after resistance exercise.

Dose‐dependent increases in p70S6K phosphorylation and intramuscular branched‐chain amino acids in older men following resistance exercise and protein intake

Resistance exercise and whey protein supplementation are effective strategies to activate muscle cell anabolic signaling and ultimately promote increases in muscle mass and strength. In the current study, 46 healthy older men aged 60–75 (69.0 ± 0.55 years, 85.9 ± 1.8 kg, 176.8 ± 1.0 cm) performed a single bout of unaccustomed lower body resistance exercise immediately followed by ingestion of a noncaloric placebo beverage or supplement containing 10, 20, 30, or 40 g of whey protein concentrate (WPC). Intramuscular amino acid levels in muscle biopsy samples were measured by Gas Chromatography–Mass Spectrometry (GC‐MS) at baseline (before exercise and WPC supplementation) plus at 2 h and 4 h post exercise. Additionally, the extent of p70S6K phosphorylation at Thr389 in muscle biopsy homogenates was assessed by western blot. Resistance exercise alone reduced intramuscular branch chain amino acid (BCAA; leucine, isoleucine, and valine) content. Supplementation with increasing doses of whey protein prevented this fall in muscle BCAAs during postexercise recovery and larger doses (30 g and 40 g) significantly augmented postexercise muscle BCAA content above that observed following placebo ingestion. Additionally, the fold change in the phosphorylation of p70S6K (Thr389) at 2 h post exercise was correlated with the dose of whey protein consumed (r = 0.51, P < 001) and was found to be significantly correlated with intramuscular leucine content (r = 0.32, P = 0.026). Intramuscular BCAAs, and leucine in particular, appear to be important regulators of anabolic signaling in aged human muscle during postexercise recovery via reversal of exercise‐induced declines in intramuscular BCAAs.

ZFAS1: a long noncoding RNA associated with ribosomes in breast cancer cells

BackgroundMost of the eukaryotic genome is transcribed, yielding a complex network of transcripts including thousands of lncRNAs that generally lack protein coding potential. However, only a small percentage of these molecules has been functionally characterised, and discoveries of specific functions demonstrate layers of complexity. A large percentage of lncRNAs is located in the cytoplasm, associated with ribosomes but the function of the majority of these transcripts is unclear. The current study analyses putative mechanisms of action of the lncRNA species member ZFAS1 that was initially discovered by microarray analysis of murine tissues undergoing mammary gland development. As developmental genes are often deregulated in cancer, here we have studied its function in breast cancer cell lines.ResultsUsing human breast cancer cell lines, ZFAS1 was found to be expressed in all cell lines tested, albeit at different levels of abundance. Following subcellular fractionation, human ZFAS1 was found in both nucleus and cytoplasm (as is the mouse orthologue) in an isoform-independent manner. Sucrose gradients based on velocity sedimentation were utilised to separate the different components of total cell lysate, and surprisingly ZFAS1 was primarily co-localised with light polysomes. Further investigation into ribosome association through subunit dissociation studies showed that ZFAS1 was predominantly associated with the 40S small ribosomal subunit. The expression levels of ZFAS1 and of mRNAs encoding several ribosomal proteins that have roles in ribosome assembly, production and maturation were tightly correlated. ZFAS1 knockdown significantly reduced RPS6 phosphorylation.ConclusionA large number of lncRNAs associate with ribosomes but the function of the majority of these lncRNAs has not been elucidated. The association of the lncRNA ZFAS1 with a subpopulation of ribosomes and the correlation with expression of mRNAs for ribosomal proteins suggest a ribosome-interacting mechanism pertaining to their assembly or biosynthetic activity. ZFAS1 may represent a new class of lncRNAs which associates with ribosomes to regulate their function.ReviewersThis article was reviewed by Christine Vande Velde, Nicola Aceto and Haruhiko Siomi.

Ibuprofen treatment blunts early translational signaling responses in human skeletal muscle following resistance exercise.

Cyclooxygenase-1 and -2 pathway-derived prostaglandins (PGs) have been implicated in adaptive muscle responses to exercise, but the role of PGs in contraction-induced muscle signaling has not been determined. We investigated the effect of inhibition of cyclooxygenase-1 and -2 activities with the nonsteroidal anti-inflammatory drug ibuprofen on human muscle signaling responses to resistance exercise. Subjects orally ingested 1,200 mg ibuprofen (or placebo control) in three 400-mg doses administered ∼30 min before and ∼6 h and ∼12 h following a bout of unaccustomed resistance exercise (80% one repetition maximum). Muscle biopsies were obtained at rest (preexercise), immediately postexercise (0 h), 3 h postexercise, and at 24 h of recovery. In the placebo (PLA) group, phosphorylation of ERK1/2 (Thr202/Tyr204), ribosomal protein S6 kinase (RSK, Ser380), mitogen-activated kinase 1 (Mnk1, Thr197/202), and p70S6 kinase (p70S6K, Thr421/Ser424) increased at both 0 and 3 h postexercise, with delayed elevation of phospho (p)-p70S6K (Thr389) and p-rpS6 (Ser235/S36 and Ser240/244) at 3 h postexercise. Only p-ERK1/2 (Thr202/Tyr204) remained significantly elevated in the 24-h postexercise biopsy. Ibuprofen treatment prevented sustained elevation of MEK-ERK signaling at 3 h (p-ERK1/2, p-RSK, p-Mnk1, p-p70S6K Thr421/Ser424) and 24 h (p-ERK1/2) postexercise, and this was associated with suppressed phosphorylation of ribosomal protein S6 (Ser235/236 and Ser240/244). Early contraction-induced p-Akt (Ser473) and p-p70S6K (Thr389) were not influenced by ibuprofen, but p-p70S6K (Thr389) remained elevated 24 h postexercise only in those receiving ibuprofen treatment. Early muscle signaling responses to resistance exercise are, in part, ibuprofen sensitive, suggesting that PGs are important signaling molecules during early postexercise recovery.

Is carbohydrate needed to further stimulate muscle protein synthesis/hypertrophy following resistance exercise?

It is now well established that protein supplementation after resistance exercise promotes increased muscle protein synthesis, which ultimately results in greater net muscle accretion, relative to exercise alone or exercise with supplementary carbohydrate ingestion. However, it is not known whether combining carbohydrate with protein produces a greater anabolic response than protein alone. Recent recommendations have been made that the composition of the ideal supplement post-exercise would be a combination of a protein source with a high glycemic index carbohydrate. This is based on the hypothesis that insulin promotes protein synthesis, thus maximising insulin secretion will maximally potentiate this action. However, it is still controversial as to whether raising insulin level, within the physiological range, has any effect to further stimulate muscle protein synthesis. The present commentary will review the evidence underpinning the recommendation to consume carbohydrates in addition to a protein supplementation after resistance exercise for the specific purpose of increasing muscle mass. The paucity of data will be discussed, thus our conclusions are that further studies are necessary prior to any conclusions that enable evidence-based recommendations to be made.

Volume for Muscle Hypertrophy and Health Outcomes: The Most Effective Variable in Resistance Training

Resistance training is the most effective method to increase muscle mass. It has also been shown to promote many health benefits. Although it is deemed safe and of clinical relevance for treating and preventing a vast number of diseases, a time-efficient and minimal dose of exercise has been the focus of a great number of research studies. Similarly, an inverted U-shaped relationship between training dose/volume and physiological response has been hypothesized to exist. However, the majority of available evidence supports a clear dose-response relationship between resistance training volume and physiological responses, such as muscle hypertrophy and health outcomes. Additionally, there is a paucity of data to support the inverted U-shaped response. Although it may indeed exist, it appears to be much more plastic than previously thought. The overarching principle argued herein is that volume is the most easily modifiable variable that has the most evidenced-based response with important repercussions, be these muscle hypertrophy or health-related outcomes.

Considerations on mTOR regulation at serine 2448: implications for muscle metabolism studies

The mammalian target of rapamycin (mTOR) complex exerts a pivotal role in protein anabolism and cell growth. Despite its importance, few studies adequately address the complexity of phosphorylation of the mTOR protein itself to enable conclusions to be drawn on the extent of kinase activation following this event. In particular, a large number of studies in the skeletal muscle biology field have measured Serine 2448 (Ser2448) phosphorylation as a proxy of mTOR kinase activity. However, the evidence to be described is that Ser2448 is not a measure of mTOR kinase activity nor is a target of AKT activity and instead has inhibitory effects on the kinase that is targeted by the downstream effector p70S6K in a negative feedback loop mechanism, which is evident when revisiting muscle research studies. It is proposed that this residue modification acts as a fine-tuning mechanism that has been gained during vertebrate evolution. In conclusion, it is recommended that Ser2448 is an inadequate measure and that preferential analysis of mTORC1 activation should focus on the downstream and effector proteins, including p70S6K and 4E-BP1, along mTOR protein partners that bind to mTOR protein to form the active complexes 1 and 2.

The effect of dietary arachidonic acid supplementation on acute muscle adaptive responses to resistance exercise in trained men: a randomized controlled trial

Arachidonic acid (ARA), a polyunsaturated ω-6 fatty acid, acts as precursor to a number of prostaglandins with potential roles in muscle anabolism. It was hypothesized that ARA supplementation might enhance the early anabolic response to resistance exercise (RE) by increasing muscle protein synthesis (MPS) via mammalian target of rapamycin (mTOR) pathway activation and/or the late anabolic response by modulating ribosome biogenesis and satellite cell expansion. Nineteen men with ≥1 yr of resistance-training experience were randomized to consume either 1.5 g daily ARA or a corn-soy-oil placebo in a double-blind manner for 4 wk. Participants then undertook fasted RE (8 sets each of leg press and extension at 80% 1-repetition maximum), with vastus lateralis biopsies obtained before exercise, immediately postexercise, and at 2, 4, and 48 h of recovery. MPS (measured via stable isotope infusion) was not different between groups ( P = 0.212) over the 4-h recovery period. mTOR pathway members p70 S6 kinase and S6 ribosomal protein were phosphorylated postexercise ( P < 0.05), with no difference between groups. 45S preribosomal RNA increased 48 h after exercise only in ARA ( P = 0.012). Neural cell adhesion molecule-positive satellite cells per fiber increased 48 h after exercise ( P = 0.013), with no difference between groups ( P = 0.331). Prior ARA supplementation did not alter the acute anabolic response to RE in previously resistance-trained men; however, at 48 h of recovery, ribosome biogenesis was stimulated only in the ARA group. The findings do not support a mechanistic link between ARA and short-term anabolism, but ARA supplementation in conjunction with resistance training may stimulate increases in translational capacity. NEW & NOTEWORTHY Four weeks of daily arachidonic acid supplementation in trained men did not alter their acute muscle protein synthetic or anabolic signaling response to resistance exercise. However, 48 h after exercise, men supplemented with arachidonic acid showed greater ribosome biogenesis and a trend toward greater change in satellite cell content. Chronic arachidonic acid supplementation does not appear to regulate the acute anabolic response to resistance exercise but may augment muscle adaptation in the following days of recovery.