Impact of local heating and cooling on skeletal muscle transcriptional response related to myogenesis and proteolysis

The combined influences of local heat application and resistance exercise on the acute mRNA response of skeletal muscle

Introduction

The development and maintenance of the skeletal muscle is crucial for the support of daily function. Heat, when applied locally, has shown substantial promise in the maintenance of the muscle. The purpose of this study was to determine the combined effects of local heat application and acute resistance exercise on gene expression associated with the human muscle growth program.

Materials and methods

Participants (n = 12, 26 ± 7 years, 1.77 ± 0.07 m, 79.6 ± 15.4 kg, and 16.1 ± 11.6 %BF) completed an acute bilateral bout of resistance exercise consisting of leg press (11 ± 2 reps; 170 ± 37 kg) and leg extension (11 ± 1 reps; 58 ± 18 kg). Participants wore a thermal wrap containing circulating fluid (40°C, exercise + heat; EX + HT) during the entire experimental period and 4 h post-exercise, while the other leg served as an exercise-only (EX) control. Biopsies of the vastus lateralis were collected (Pre, Post, and 4hPost) for gene expression analyses.

Results

Intramuscular temperatures increased (Post, +2.2°C ± 0.7°C, and p < 0.001; 4hPost, +2.5°C ± 0.6°C, and p < 0.001) and were greater in the EX + HT leg post-exercise (+0.35°C ± 0.3°C, and p = 0.005) and after 4hPost (+2.1°C ± 0.8°C and p < 0.001). MYO-D1 mRNA was greater in the EX + HT leg vs. the EX (fold change = 2.74 ± 0.42 vs. 1.70 ± 0.28, p = 0.037). No other genes demonstrated temperature sensitivity when comparing both legs (p > 0.05). mRNA associated with the negative regulator, myostatin (MSTN), decreased post-exercise (p = 0.001) and after 4 h (p = 0.001). mRNA associated with proteolysis decreased post-exercise (FBXO32, p = 0.001; FOXO3a, p = 0.001) and after 4 h (FBXO32, p = 0.001; FOXO3a, p = 0.027).

Conclusion

The elevated transcription of the myogenic differentiation factor 1 (MYO-D1) after exercise in the heated condition may provide a mechanism by which muscle growth could be enhanced.

Oleanolic acid alleviates obesity-induced skeletal muscle atrophy via the PI3K/Akt signaling pathway

Oleanolic acid (OA) is a pentacyclic triterpene with reported protective effects against various diseases, including diabetes, hepatitis, and different cancers. However, the effects of OA on obesity-induced muscle atrophy remain largely unknown. This study investigated the effects of OA on skeletal muscle production and proliferation of C2C12 cells. We report that OA significantly increased skeletal muscle mass and improved glucose intolerance and insulin resistance. OA inhibited dexamethasone (Dex)-induced muscle atrophy in C2C12 myoblasts by regulating the PI3K/Akt signaling pathway. In addition, it also inhibited expression of MuRF1 and Atrogin1 genes in skeletal muscle of obese mice suffering from muscle atrophy, and increased the activation of PI3K and Akt, thereby promoting protein synthesis, and eventually alleviating muscle atrophy. Taken together, these findings suggest OA may have potential for the prevention and treatment of muscle atrophy.

The isolated effects of local cold application on proteolytic and myogenic signaling

Post-exercise cooling studies reveal inhibitory effects on markers of skeletal muscle growth. However, the isolated effect of local cold application has not been adequately addressed. It is unclear if the local cold or the combination of local cold and exercise is driving negatively altered skeletal muscle gene expression. The purpose was to determine the effects of a 4 h local cold application to the vastus lateralis on the myogenic and proteolytic response. Participants (n = 12, 27 ± 6 years, 179 ± 9 cm, 82.8 ± 13.0 kg, 18.4 ± 7.1 %BF) rested with a thermal wrap placed on each leg with either circulating cold fluid (10 °C, COLD) or no fluid circulation (room temperature, RT). Muscle samples were collected to quantify mRNA (RT-qPCR) and proteins (Western Blot) associated with myogenesis and proteolysis. Temperatures in COLD were lower than RT at the skin (13.2 ± 1.0 °C vs. 34.8 ± 0.9 °C; p < 0.001) and intramuscularly (20.5 ± 1.3 °C vs. 35.6 ± 0.8 °C, p < 0.001). Myogenic-related mRNA, MYO-G and MYO-D1, were lower in COLD (p = 0.001, p < 0.001, respectively) whereas myogenic-mRNA, MYF6, was greater in COLD (p = 0.002). No other myogenic associated genes were different between COLD and RT (MSTN, p = 0.643; MEF2a, p = 0.424; MYF5, p = 0.523; RPS3, p = 0.589; RPL3-L, p = 0.688). Proteolytic-related mRNA was higher in COLD (FOXO3a, p < 0.001; Atrogin-1, p = 0.049; MURF-1, p < 0.001). The phosphorylation:total protein ratio for the translational repressor of muscle mass, 4E-BP1Thr37/46, was lower in COLD (p = 0.043), with no differences in mTORser2448 (p = 0.509) or p70S6K1Thr389 (p = 0.579). Isolated local cooling over 4 h exhibits inhibited myogenic and higher proteolytic skeletal muscle molecular response.

The independent effects of local heat application on muscle growth program associated mRNA and protein phosphorylation

The development and maintenance of skeletal muscle is crucial for the support of daily function. Recent evidence suggests that genes coded for proteins associated with the human muscle growth program (myogenic and proteolytic genes) are sensitive to local heat application. Therefore, the purpose of this investigation was to determine the effect of 4 h of local heat application to the vastus lateralis at rest on acute phosphorylation (mTORSer2448, p70-S6K1Thr389, and 4E-BP1Thr47/36) and gene expression changes for proteins associated with the muscle growth program. Intramuscular temperature of the HOT limb was 1.2 ± 0.2 °C higher than CON limb after 4 h of local heating. However, this local heat stimulus did not influence transcription of genes associated with myogenesis (MSTN, p = 0.321; MYF5, p = 0.445; MYF6, p = 0.895; MEF2a, p = 0.809; MYO-G, p = 0.766; MYO-D1, p = 0.118; RPS3, p = 0.321; and RPL-3L, p = 0.577), proteolysis (Atrogin-1, p = 0.573; FOXO3a, p = 0.452; MURF-1, p = 0.284), nor protein phosphorylation (mTORSer2448, p = 0.981; P70-S6K1Thr389, p = 0.583; 4E-BP1Thr37/46, p = 0.238) associated with the muscle growth program. These findings suggest little to no association between the local application of heat, at rest, and the activation of the observed muscle growth program-related markers.

Interrelated but Not Time-Aligned Response in Myogenic Regulatory Factors Demethylation and mRNA Expression after Divergent Exercise Bouts

INTRODUCTION

DNA methylation regulates exercise-induced changes in the skeletal muscle transcriptome. However, the specificity and the time course responses in the myogenic regulatory factors DNA methylation and mRNA expression after divergent exercise modes are unknown.

PURPOSE

This study aimed to compare the time course changes in DNA methylation and mRNA expression for selected myogenic regulatory factors ( MYOD1 , MYF5 , and MYF6 ) immediately after, 4 h after, and 8 h after a single bout of resistance exercise (RE), high-intensity interval exercise (HIIE), and concurrent exercise (CE).

METHODS

Nine healthy but untrained males (age, 23.9 ± 2.8 yr; body mass, 70.1 ± 14.9 kg; peak oxygen uptake [V̇O 2peak ], 41.4 ± 5.2 mL·kg -1 ·min -1 ; mean ± SD) performed a counterbalanced, randomized order of RE (4 × 8-12 repetition maximum), HIIE (12 × 1 min sprints at V̇O 2peak running velocity), and CE (RE followed by HIIE). Skeletal muscle biopsies (vastus lateralis) were taken before (REST) immediately (0 h), 4 h, and 8 h after each exercise bout.

RESULTS

Compared with REST, MYOD1 , MYF5 , and MYF6 , mean methylation across all CpGs analyzed was reduced after 4 and 8 h in response to all exercise protocols ( P < 0.05). Reduced levels of MYOD1 methylation were observed after HIIE and CE compared with RE ( P < 0.05). Compared with REST, all exercise bouts increased mRNA expression over time ( MYOD1 at 4 and 8 h, and MYF6 at 4 h; P < 0.05). MYF5 mRNA expression was lower after 4 h compared with 0 h and higher at 8 h compared with 4 h ( P < 0.05).

CONCLUSIONS

We observed an interrelated but not time-aligned response between the exercise-induced changes in myogenic regulatory factors demethylation and mRNA expression after divergent exercise modes. Despite divergent contractile stimuli, changes in DNA methylation and mRNA expression in skeletal muscle were largely confined to the late (4-8 h) recovery period and similar between the different exercise challenges.

A Conformable Two-Dimensional Resistance Temperature Detector for Measuring Average Skin Temperature

Thermoregulation research and various medical procedures are accomplished by manipulating skin temperature in a nonuniform pattern. Skin temperature monitoring is essential to assess conformance to protocol specifications and to prevent thermal injury. Existing solutions for skin temperature monitoring include single point sensors, such as thermocouples, and two-dimensional methods of sensing surface temperature, such as infrared thermography, and wearable technology. Single point sensors cannot detect the average temperature and consequently their measurements cannot be representative of average surface temperature in a nonuniform temperature field. Infrared thermography requires optical access, and existing ambulatory sensors may require complex manufacturing processes and impede the heat exchange with a source by including a structural substrate layer. Our solution is a two-dimensional resistance temperature detector (two-dimensional (2D) RTD) created by knitting copper magnet wire into custom shapes. The 2D RTDs were calibrated, compared to one-dimensional sensors and wearable sensors, and analyzed for hysteresis, repeatability, and surface area conformation. Resistance and temperature were correlated with an R² of 0.99. The 2D RTD proved to be a superior device for measuring average skin temperature over a defined area exposed to a nonuniform temperature boundary in the absence of optical access such as when a full body thermal control garment is worn.

Novel methods for cold exposure of skeletal muscle in vivo and in vitro show temperature-dependent myokine production

Proteins secreted from skeletal muscle serving a signalling role have been termed myokines. Many of the myokines are exercise factors, produced and released in response to muscle activity. Cold exposures affecting muscle may occur in recreational, occupational and therapeutic settings. Whether muscle temperature independently affects myokine profile, is still to be elucidated. We hypothesized that manipulating muscle temperature by means of external cooling would change myokine production and release. In the present study we have established new models for cold exposure of muscle in vivo and in vitro where rat hind limb or cultured human myotubes were cooled to 18 °C. After a recovery period, muscle tissue, cells and culture media were harvested for further analysis by qPCR and immunoassays. Expression of several myokine genes were significantly increased after cold exposure in both models: in rat muscle, mRNA levels of CCL2 (p = 0.04), VEGFA (p = 0.02), CXCL1 (p = 0.02) and RBM3 (p = 0.02) increased while mRNA levels of IL-6 (p = 0.03) were decreased; in human myotubes, mRNA levels of IL6 (p = 0.01), CXCL8 (p = 0.04), VEGFA (p = 0.03) and CXCL1 (p < 0.01) were significantly increased, as well as intracellular protein levels of IL-8 (CXCL8 gene product; p < 0.01). The corresponding effect on myokine secretion was not observed, on the contrary, IL-8 (p = 0.02) and VEGF (VEGFA gene product) p < 0.01) concentrations in culture media were reduced after cold exposure in vitro. In conclusion, cold exposure of muscle in vivo and in vitro had an effect on the production and release of several known exercise-related myokines. Myokine expression at the level of mRNA and protein was increased by cold exposure, whereas secretion tended to be decreased.

Beneficial effects of whole-body cryotherapy on glucose homeostasis and amino acid profile are associated with a reduced myostatin serum concentration

The study investigated the effect of single and chronic (10 sessions) whole-body cryotherapy (WBC; 3-min, − 110 °C) on amino acid (AA) profile, myostatin, fibroblast growth factor 21 (FGF21), and concentrations of brain-derived neurotrophic factor (BDNF), irisin and adiponectin in relation to glucose homeostasis. Thirty-five, healthy men were randomly split into experimental (young: 28 ± 7 years and middle-aged: 51 ± 3 years) and control groups. Blood samples were taken before and 1 h after the first and last (10th) WBC session. Baseline myostatin correlated significantly with visceral fat area, glucose, insulin, HOMA-IR and irisin (all p < 0.05). The single session of WBC induced temporary changes in AA profile, whereas chronic exposure lowered valine and asparagine concentrations (p < 0.01 and p = 0.01, respectively) compared to the baseline. The chronic WBC reduced fasting glucose (p = 0.04), FGF21 (− 35.8%, p = 0.06) and myostatin (-18.2%, p = 0.06). Still, the effects were age-dependent. The decrease of myostatin was more pronounced in middle-aged participants (p < 0.01). Concentrations of irisin and adiponectin increased in response to chronic WBC, while BDNF level remained unchanged. By improving the adipo-myokine profile, chronic WBC may reduce effectively the risk of the metabolic syndrome associated with hyperinsulinemia, increased levels of valine and asparagine, and muscle atrophy.

Effect of local cold application during exercise on gene expression related to mitochondrial homeostasis

Exercise training increases mitochondrial content in active skeletal muscle. Previous work suggests that mitochondrial-related genes respond favorably to exercise in cold environments. However, the impact of localized tissue cooling is unknown. The purpose of this study was to determine the impact of local muscle cooling during endurance exercise on human skeletal muscle mitochondrial-related gene expression. Twelve subjects (age, 28 ± 6 years) cycled at 65% peak power output. One leg was cooled (C) for 30 min before and during exercise with a thermal wrap while the other leg was wrapped but not cooled, room temperature (RT). Muscle biopsies were taken from each vastus lateralis before and 4 h after exercise for the analysis of gene expression. Muscle temperature was lower in the C (29.2 ± 0.7 °C) than the RT (34.1 ± 0.3 °C) condition after pre-cooling for 30 min before exercise (p < 0.001) and remained lower after exercise in the C (36.9 ± 0.5) than the RT (38.4 ± 0.2, p < 0.001) condition. PGC-1α and NRF1 mRNA expression were lower in the C (p = 0.012 and p = 0.045, respectively) than the RT condition at 4 h after exercise. There were no temperature-related differences in other genes (p > 0.05). These data suggest that local cooling has an inhibitory effect on exercise-induced PGC-1α and NRF1 expression in human skeletal muscle. Those considering using local cooling during exercise should consider other systemic cooling options. Novelty: Local cooling has an inhibitory effect on exercise-induced PGC-1α and NRF1 expression in human skeletal muscle. Local cooling may lead to a less robust exercise stimulus compared with standard conditions.

The Effects of Cold Water Immersion and Active Recovery on Molecular Factors That Regulate Growth and Remodeling of Skeletal Muscle After Resistance Exercise

Regular postexercise cooling attenuates muscle hypertrophy, yet its effects on the key molecular factors that regulate muscle growth and remodeling are not well characterized. In the present study, nine men completed two sessions of single-leg resistance exercise on separate days. On 1 day, they sat in cold water (10°C) up to their waist for 10 min after exercise. On the other day, they exercised at a low intensity for 10 min after exercise. Muscle biopsies were collected from the exercised leg before, 2, 24, and 48 h after exercise in both trials. These muscle samples were analyzed to evaluate changes in genes and proteins involved in muscle growth and remodeling. Muscle-specific RING finger 1 mRNA increased at 2 h after both trials (P < 0.05), while insulin-like growth factor (IGF)-1 Ec, IGF-1 receptor, growth arrest and DNA damage-inducible protein 45, collagen type I alpha chain A, collagen type III alpha chain 1, laminin and tissue inhibitor of metallopeptidase 1 mRNA increased 24−48 h after both trials (P < 0.05). By contrast, atrogin-1 mRNA decreased at all time points after both trials (P < 0.05). Protein expression of tenascin C increased 2 h after the active recovery trial (P < 0.05), whereas FoxO3a protein expression decreased after both trials (P < 0.05). Myostatin mRNA and ubiquitin protein expression did not change after either trial. These responses were not significantly different between the trials. The present findings suggest that regular cold water immersion attenuates muscle hypertrophy independently of changes in factors that regulate myogenesis, proteolysis and extracellular matrix remodeling in muscle after exercise.

Hot-water immersion does not increase postprandial muscle protein synthesis rates during recovery from resistance-type exercise in healthy, young males

The purpose of this study was to assess the impact of postexercise hot-water immersion on postprandial myofibrillar protein synthesis rates during recovery from a single bout of resistance-type exercise in healthy, young men. Twelve healthy, adult men (age: 23 ± 1 y) performed a single bout of resistance-type exercise followed by 20 min of water immersion of both legs. One leg was immersed in hot water [46°C: hot-water immersion (HWI)], while the other leg was immersed in thermoneutral water (30°C: CON). After water immersion, a beverage was ingested containing 20 g intrinsically L-[1-¹³C]-phenylalanine and L-[1-¹³C]-leucine labeled milk protein with 45 g of carbohydrates. In addition, primed continuous L-[ring-²H₅]-phenylalanine and L-[1-¹³C]-leucine infusions were applied, with frequent collection of blood and muscle samples to assess myofibrillar protein synthesis rates in vivo over a 5-h recovery period. Muscle temperature immediately after water immersion was higher in the HWI compared with the CON leg (37.5 ± 0.1 vs. 35.2 ± 0.2°C; P < 0.001). Incorporation of dietary protein-derived L-[1-¹³C]-phenylalanine into myofibrillar protein did not differ between the HWI and CON leg during the 5-h recovery period (0.025 ± 0.003 vs. 0.024 ± 0.002 MPE; P = 0.953). Postexercise myofibrillar protein synthesis rates did not differ between the HWI and CON leg based upon L-[1-¹³C]-leucine (0.050 ± 0.005 vs. 0.049 ± 0.002%/h; P = 0.815) and L-[ring-²H₅]-phenylalanine (0.048 ± 0.002 vs. 0.047 ± 0.003%/h; P = 0.877), respectively. Hot-water immersion during recovery from resistance-type exercise does not increase the postprandial rise in myofibrillar protein synthesis rates. In addition, postexercise hot-water immersion does not increase the capacity of the muscle to incorporate dietary protein-derived amino acids in muscle tissue protein during subsequent recovery.NEW & NOTEWORTHY This is the first study to assess the effect of postexercise hot-water immersion on postprandial myofibrillar protein synthesis rates and the incorporation of dietary protein-derived amino acids into muscle protein. We observed that hot-water immersion during recovery from a single bout of resistance-type exercise does not further increase myofibrillar protein synthesis rates or augment the postprandial incorporation of dietary protein-derived amino acids in muscle throughout 5 h of postexercise recovery.

Effects of 7°C environmental temperature acclimation during a 3-week training period

Cold environmental temperatures during exercise and recovery alter the acute response to cellular signaling and training adaptations. Approximately 3 wk is required for cold temperature acclimation to occur. To determine the impact of cold environmental temperature on training adaptations, fitness measurements, and aerobic performance, two groups of 12 untrained male subjects completed 1 h of cycling in 16 temperature acclimation sessions in either a 7°C or 20°C environmental temperature. Fitness assessments before and after acclimation occurred at standard room temperature. Muscle biopsies were taken from the vastus lateralis muscle before and after training to assess molecular markers related to mitochondrial development. Peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) mRNA was higher in 7°C than in 20°C in response to acute exercise before training (P = 0.012) but not after training (P = 0.813). PGC-1α mRNA was lower after training (P < 0.001). BNIP3 was lower after training in the 7°C than in the 20°C group (P = 0.017) but not before training (P = 0.549). No other differences occurred between temperature groups in VEGF, ERRα, NRF1, NRF2, TFAM, PINK1, Parkin, or BNIP3L mRNAs (P > 0.05). PGC-1α protein and mtDNA were not different before training, after training, or between temperatures (P > 0.05). Cycling power increased during the daily training (P < 0.001) but was not different between temperatures (P = 0.169). V̇o_2peak increased with training (P < 0.001) but was not different between temperature groups (P = 0.460). These data indicate that a 3-wk period of acclimation/training in cold environmental temperatures alters PGC-1α gene expression acutely but this difference is not manifested in a greater increase in V̇o_2peak and is dissipated as acclimation takes place.NEW & NOTEWORTHY This study examines the adaptive response of cellular signaling during exercise in cold environmental temperatures. We demonstrate that peroxisome proliferator-activated receptor-γ coactivator 1α mRNA is different between cold and room temperature environments before training but after training this difference no longer exists. This initial difference in transcriptional response between temperatures does not lead to differences in performance measures or increases in protein or mitochondria.

Postexercise cooling impairs muscle protein synthesis rates in recreational athletes

Key points

Protein ingestion and cooling are strategies employed by athletes to improve postexercise recovery and, as such, to facilitate muscle conditioning. However, whether cooling affects postprandial protein handling and subsequent muscle protein synthesis rates during recovery from exercise has not been assessed.

We investigated the effect of postexercise cooling on the incorporation of dietary protein‐derived amino acids into muscle protein and acute postprandial (hourly) as well as prolonged (daily) myofibrillar protein synthesis rates during recovery from resistance‐type exercise over 2 weeks.

Cold‐water immersion during recovery from resistance‐type exercise lowers the capacity of the muscle to take up and/or direct dietary protein‐derived amino acids towards de novo myofibrillar protein accretion. In addition, cold‐water immersion during recovery from resistance‐type exercise lowers myofibrillar protein synthesis rates during prolonged resistance‐type exercise training.

Individuals aiming to improve skeletal muscle conditioning should reconsider applying cooling as a part of their postexercise recovery strategy.

Abstract

We measured the impact of postexercise cooling on acute postprandial (hourly) as well as prolonged (daily) myofibrillar protein synthesis rates during adaptation to resistance‐type exercise over 2 weeks. Twelve healthy males (aged 21 ± 2 years) performed a single resistance‐type exercise session followed by water immersion of both legs for 20 min. One leg was immersed in cold water (8°C: CWI), whereas the other leg was immersed in thermoneutral water (30°C: CON). After water immersion, a beverage was ingested containing 20 g of intrinsically (l‐[1‐¹³C]‐phenylalanine and l‐[1‐¹³C]‐leucine) labelled milk protein with 45 g of carbohydrates. In addition, primed continuous l‐[ring‐²H₅]‐phenylalanine and l‐[1‐¹³C]‐leucine infusions were applied, with frequent collection of blood and muscle samples to assess myofibrillar protein synthesis rates in vivo over a 5 h recovery period. In addition, deuterated water (²H₂O) was applied with the collection of saliva, blood and muscle biopsies over 2 weeks to assess the effects of postexercise cooling with protein intake on myofibrillar protein synthesis rates during more prolonged resistance‐type exercise training (thereby reflecting short‐term training adaptation). Incorporation of dietary protein‐derived l‐[1‐¹³C]‐phenylalanine into myofibrillar protein was significantly lower in CWI compared to CON (0.016 ± 0.006 vs. 0.021 ± 0.007 MPE; P = 0.016). Postexercise myofibrillar protein synthesis rates were lower in CWI compared to CON based upon l‐[1‐¹³C]‐leucine (0.058 ± 0.011 vs. 0.072 ± 0.017% h⁻¹, respectively; P = 0.024) and l‐[ring‐²H₅]‐phenylalanine (0.042 ± 0.009 vs. 0.053 ± 0.013% h⁻¹, respectively; P = 0.025). Daily myofibrillar protein synthesis rates assessed over 2 weeks were significantly lower in CWI compared to CON (1.48 ± 0.17 vs. 1.67 ± 0.36% day⁻¹, respectively; P = 0.042). Cold‐water immersion during recovery from resistance‐type exercise reduces myofibrillar protein synthesis rates and, as such, probably impairs muscle conditioning.

Protein ingestion and cooling are strategies employed by athletes to improve postexercise recovery and, as such, to facilitate muscle conditioning. However, whether cooling affects postprandial protein handling and subsequent muscle protein synthesis rates during recovery from exercise has not been assessed.

We investigated the effect of postexercise cooling on the incorporation of dietary protein‐derived amino acids into muscle protein and acute postprandial (hourly) as well as prolonged (daily) myofibrillar protein synthesis rates during recovery from resistance‐type exercise over 2 weeks.

Cold‐water immersion during recovery from resistance‐type exercise lowers the capacity of the muscle to take up and/or direct dietary protein‐derived amino acids towards de novo myofibrillar protein accretion. In addition, cold‐water immersion during recovery from resistance‐type exercise lowers myofibrillar protein synthesis rates during prolonged resistance‐type exercise training.

Individuals aiming to improve skeletal muscle conditioning should reconsider applying cooling as a part of their postexercise recovery strategy.

E-Textiles for Healthy Ageing

The ageing population has grown quickly in the last half century with increased longevity and declining birth rate. This presents challenges to health services and the wider society. This review paper considers different aspects (e.g., physical, mental, and social well-being) of healthy ageing and how health devices can help people to monitor health conditions, treat diseases and promote social interactions. Existing technologies for addressing non-physical (e.g., Alzheimer's, loneliness) and physical (e.g., stroke, bedsores, and fall) related challenges are presented together with the drivers and constraints of using e-textiles for these applications. E-textiles provide a platform that enables unobtrusive and ubiquitous deployment of sensors and actuators for healthy ageing applications. However, constraints remain on battery, integration, data accuracy, manufacturing, durability, ethics/privacy issues, and regulations. These challenges can only effectively be met by interdisciplinary teams sharing expertise and methods, and involving end users and other key stakeholders at an early stage in the research.

An oleanolic acid derivative reduces denervation-induced muscle atrophy via activation of CNTF-mediated JAK2/STAT3 signaling pathway

Denervation caused by sciatic nerve injury has brought great harm to the patients, especially denervation-induced muscle atrophy. The body stress produces a large number of Schwann cells when the sciatic nerve is injured, and the cells secrete some cytokines including ciliary neurotrophic factor (CNTF) that not only play a role in promoting the repair of sciatic nerve, but also maintain the normal physiological function of the muscles surrounding the damaged nerves. CNTF upregulates janus kinase 2 (JAK2) and signal transducers and activators of transcription 3 (STAT3) signals in myoblasts, and consequently accelerates the proliferation and differentiation of myoblasts. This effect on myoblasts is the most effective way to relieve muscle atrophy. Therefore, increasing CNTF is a promising direction to improve muscle atrophy. In the present study, an oleanolic acid derivative, HA-19, increased the proliferation of Schwann cells, and elevated CNTF production of the cells. HA-19 up-regulated the phosphorylation of JAK2 and STAT3 not only by directly acting on myoblasts, but also by increasing the secretion of CNTF of Schwann cells; and consequently, promoted the proliferation and differentiation of myoblasts. In denervation-induced muscle atrophy mice model, treatment with HA-19 significantly increased the weights of tibialis anterior (TA), gastrocnemius (Gastroc.), extensor digitorum longus (EDL), soleus and quadriceps (Quad.) under atrophied state. And, very interestingly, these muscles under normal condition were also strengthened by HA-19. Our finding demonstrated that HA-19 has a great potential as a lead compound for the drug discovery of anti-denervation-induced muscle atrophy.

A novel oleanolic acid derivative HA-19 ameliorates muscle atrophy via promoting protein synthesis and preventing protein degradation

Muscle atrophy refers to a decrease in the size of muscles in the body, occurs in certain muscles with inactivity in many diseases and lacks effective therapies up to date. Natural products still play an important role in drug discovery. In the present study, derivatives of a natural product, oleanolic acid, were screened with myoblast differentiation and myotube atrophy assays, respectively. Results revealed that one of the derivatives, HA-19 showed the most potent anti-muscle atrophy activity, and was used for further studies. We demonstrated that HA-19 led to the increase of the protein synthesis by activating mechanistic target of rapamycin complex 1 (mTORC1)/p70 S6K pathways, and also enhanced myoblast proliferation and terminal differentiation via up-regulating of the myogenic transcription factors Pax7, MyoD and Myogenin. The interesting thing was that HA-19 also suppressed protein degradation to prevent myotube atrophy by down-regulating negative growth factors, FoxO1, MuRF1 and Atrogin-1. The results were also supported by puromycin labelling and protein ubiquitination assays. These data revealed that HA-19 possessed a "dual effect" on inhibition of muscle atrophy. In disuse-induced muscle atrophy mice model, HA-19 treatment significantly increased the weights of bilateral tibialis anterior (TA), gastrocnemius (Gastroc.), quadriceps (Quad.), suggesting the effectiveness of HA-19 to remit disuse-induced muscle atrophy. Our finding demonstrated that HA-19 has a great potential as an inhibitor or lead compound for the anti-muscle atrophy drug discovery.

Negative Energy Balance Does Not Alter Fat-Free Mass During the Yukon Arctic Ultra-The Longest and the Coldest Ultramarathon

Purpose: The objective of this study was to determine alterations in caloric balance, body composition, metabolites, and cytokines in athletes participating in the Yukon Arctic Ultra.

Methods: Ten participants traveling on foot in the 2017 692-km event were recruited for the study. Measurements and samples were obtained at pre-event, 278 km (C1), 384 km (C2), and post-event. Body composition measurements were obtained using bioelectrical impedance analysis. Accelerometer devices were utilized to provide an estimation of caloric expenditure and dietary recalls provided assessments of caloric intake. Blood serum samples were collected, processed, and analyzed using enzyme-linked immunosorbent assays or nuclear magnetic resonance. Results were analyzed using linear mixed model, presented as means ± SD, and considered significant at p < 0.05.

Results: Participants (8 males, 2 females; age: 37 ± 10 years; body mass index: 24.4 ± 2.5 kg/m²) were recruited. Four males and one female completed the entire event in 260 ± 19 h. Caloric intake/expenditure was 4,126 ± 1,115 kcal/day and 6,387 ± 781 kcal/day, respectively, indicating a caloric deficit of 2,261 ± 1,543 kcal/day. Total mass, body mass index, and fat mass were reduced at each time point of the event. Fat-free mass (FFM) was unchanged throughout the event. Follistatin was increased at C1 (1,715 ± 876 pg/ml) in comparison to baseline. Acetoacetate increased significantly at post-event (6.1 ± 1.5 mg/ml).

Conclusions: Despite a pronounced caloric deficit and sustained activity under extreme cold conditions, FFM was preserved with an increase in serum follistatin and acetoacetate. Future studies should be directed at the role of nutrient strategies and/or training methods on the retention of FFM under these conditions.