Key pointsr 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.r 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.r 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.r 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.Abstract We investigated functional, morphological and molecular adaptations to strength training exercise and cold water immersion (CWI) through two separate studies. In one study, 21 physically active men strength trained for 12 weeks (2 days per week), with either 10 min of CWI or active recovery (ACT) after each training session. Strength and muscle mass increased more in the ACT group than in the CWI group (P < 0.05). Isokinetic work (19%), type II muscle fibre cross-sectional area (17%) and the number of myonuclei per fibre (26%) increased in the ACT group (all P < 0.05), but not the CWI group. In another study, nine active men performed a bout of single-leg strength exercises on separate days, followed by CWI or ACT. Muscle biopsies were collected before and 2, 24 and 48 h after exercise. The number of satellite cells expressing neural cell adhesion molecule (NCAM) (10−30%) and paired box protein (Pax7) (20−50%) increased 24-48 h after exercise with ACT. The number of NCAM + satellite cells increased 48 h after exercise with CWI. NCAM + -and Pax7 + -positive satellite cell numbers were greater after ACT than after CWI (P < 0.05). Phosphorylation of p70S6 kinase Thr421/Ser424 increased after exercise in both conditions but was greater after ACT (P < 0.05). These data suggest that CWI attenuates the acute changes in satellite cell numbers and activity of kinases that regulate muscle hypertrophy, which Abbreviations DAPI, 4 ,6-diamidino-2-phenylindole; ERK, extracellular regulated kinase; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; MRI, magnetic resonance imaging; mTOR, mammalian target of rapamycin; NCAM, neural cell adhesion molecule; Pax7, paired box protein 7; p70S6K, p70S6 kinase; RFD, rate of force development; RIPA, radioimmunoprecipitation assay; RM, repetition maximum; rpS6, ribosomal protein S6; Ser, serine; Thr, threonine; Tyr, tyrosine; 4E-BP1, (eukaryotic translation initiation factor) 4E-binding protein1.

Classical proinflammatory eicosanoids, and more recently discovered lipid mediators with anti-inflammatory and proresolving bioactivity, exert a complex role in the initiation, control, and resolution of inflammation. Using a targeted lipidomics approach, we investigated circulating lipid mediator responses to resistance exercise and treatment with the NSAID ibuprofen. Human subjects undertook a single bout of unaccustomed resistance exercise (80% of one repetition maximum) following oral ingestion of ibuprofen (400 mg) or placebo control. Venous blood was collected during early recovery (0 -3 h and 24 h postexercise), and serum lipid mediator composition was analyzed by LC-MS-based targeted lipidomics. Postexercise recovery was characterized by elevated levels of cyclooxygenase (COX)-1 and 2-derived prostanoids (TXB2, PGE2, PGD2, PGF2␣, and PGI2), lipooxygenase (5-LOX, 12-LOX, and 15-LOX)-derived hydroxyeicosatetraenoic acids (HETEs), and leukotrienes (e.g., LTB4), and epoxygenase (CYP)-derived epoxy/dihydroxy eicosatrienoic acids (EpETrEs/DiHETrEs). Additionally, we detected elevated levels of bioactive lipid mediators with anti-inflammatory and proresolving properties, including arachidonic acid-derived lipoxins (LXA4 and LXB4), and the EPA (E-series) and DHA (D-series)-derived resolvins (RvD1 and RvE1), and protectins (PD1 isomer 10S, 17S-diHDoHE). Ibuprofen treatment blocked exercise-induced increases in COX-1 and COX-2-derived prostanoids but also resulted in off-target reductions in leukotriene biosynthesis, and a diminished proresolving lipid mediator response. CYP pathway product metabolism was also altered by ibuprofen treatment, as indicated by elevated postexercise serum 5,6-DiHETrE and 8,9-DiHETrE only in those receiving ibuprofen. These findings characterize the blood inflammatory lipid mediator response to unaccustomed resistance exercise in humans and show that acute proinflammatory signals are mechanistically linked to the induction of a biological active inflammatory resolution program, regulated by proresolving lipid mediators during postexercise recovery. eicosanoid; exercise; inflammation; nonsteroidal anti-inflammatory drug; resolution LIPID MEDIATORS ARE A DIVERSE class of bioactive autocrine/ paracrine signaling molecules that are synthesized endogenously from essential omega-6 and omega-3 fatty acids. Oxidation of free fatty acid substrates via cyclooxygenase (COX-1 and COX-2), lipoxygenase (5-LOX, 12-LOX, and 15-LOX), epoxygenase (CYP), and nonenzymatic pathways, produces a potential array of more than 100 distinct lipid mediators. Bioactive lipid mediators are involved in a wide range of physiological and pathological processes, one of the best characterized of which is their key role in the inflammatory response (reviewed in Ref. 91). Classical eicosanoids derived from omega-6 arachidonic acid (AA, -6 20:4), including prostaglandins (PGs; synthesized via COX-1 and COX-2) and leukotrienes (LTs, synthesized via 5-LOX), are well established proinflammatory signaling molecules that stimul...

-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 Ϯ 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. ribosomal RNA; cyclin D1; upstream binding protein; transcription initiation factor 1A

This study investigated the effects of high-intensity interval training (HIIT) vs. work-matched moderate-intensity continuous exercise (MOD) on metabolism and counterregulatory stress hormones. In a randomized and counterbalanced order, 10 well-trained male cyclists and triathletes completed a HIIT session [81.6 Ϯ 3.7% maximum oxygen consumption (V O2 max); 72.0 Ϯ 3.2% peak power output; 792 Ϯ 95 kJ] and a MOD session (66.7 Ϯ 3.5% V O2 max; 48.5 Ϯ 3.1% peak power output; 797 Ϯ 95 kJ). Blood samples were collected before, immediately after, and 1 and 2 h postexercise. Carbohydrate oxidation was higher (P ϭ 0.037; 20%), whereas fat oxidation was lower (P ϭ 0.037; Ϫ47%) during HIIT vs. MOD. Immediately after exercise, plasma glucose (P ϭ 0.024; 20%) and lactate (P Ͻ 0.01; 5.4ϫ) were higher in HIIT vs. MOD, whereas total serum free fatty acid concentration was not significantly different (P ϭ 0.33). Targeted gas chromatography-mass spectromtery metabolomics analysis identified and quantified 49 metabolites in plasma, among which 11 changed after both HIIT and MOD, 13 changed only after HIIT, and 5 changed only after MOD. Notable changes included substantial increases in tricarboxylic acid intermediates and monounsaturated fatty acids after HIIT and marked decreases in amino acids during recovery from both trials. Plasma adrenocorticotrophic hormone (P ϭ 0.019), cortisol (P Ͻ 0.01), and growth hormone (P Ͻ 0.01) were all higher immediately after HIIT. Plasma norepinephrine (P ϭ 0.11) and interleukin-6 (P ϭ 0.20) immediately after exercise were not significantly different between trials. Plasma insulin decreased during recovery from both HIIT and MOD (P Ͻ 0.01). These data indicate distinct differences in specific metabolites and counterregulatory hormones following HIIT vs. MOD and highlight the value of targeted metabolomic analysis to provide more detailed insights into the metabolic demands of exercise. exercise intensity; metabolites; stress hormones; amino acids; free fatty acids; tricarboxylic acid intermediates INTEREST IN HIGH-INTENSITY exercise as an effective mode of exercise training has intensified over the past decade in recognition of three main factors that are commonly cited as limitations to regular physical activity: lack of time, lack of motivation, and chronic diseases that restrict work capacity during exercise (64). This type of training generally consists of relatively brief, intermittent exercise performed either at "allout" effort or at intensities close to maximum oxygen consumption (V O 2 max ) (16). The body of literature supporting the health and fitness benefits of high-intensity interval training (HIIT) is expanding. So too is our knowledge of the molecular mechanisms that accompany adaptations to this form of training (19).Improved metabolism is integral to the benefits of HIIT. Carbohydrate (CHO) oxidation increases with exercise intensity, whereas fat oxidation increases during exercise up to 65-75% V O 2 max and decreases at higher workloads (52, 60). Exercise also stimulates amino ...