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Whey protein ingestion during recovery from exercise increases myofibrillar but not muscle connective protein synthesis rates. It has been speculated that whey protein does not provide sufficient glycine to maximize postexercise muscle connective protein synthesis rates. In the present study, we assessed the impact of coingesting different amounts of collagen with whey protein as a nutritional strategy to increase plasma glycine availability during recovery from exercise. In a randomized, double-blind, crossover design, 14 recreationally active men (age: 26 ± 5 years; body mass index: 23.8 ± 2.1 kg·m−2) ingested in total 30 g protein, provided as whey protein with 0 g (WHEY), 5 g (WC05); 10 g (WC10), and 15 g (WC15) of collagen protein immediately after a single bout of resistance exercise. Blood samples were collected frequently over 6 hr of postexercise recovery to assess postprandial plasma amino acid kinetics and availability. Protein ingestion strongly increased plasma amino acid concentrations (p <.001) with no differences in plasma total amino acid availability between treatments (p >.05). The postprandial rise in plasma leucine and essential amino acid availability was greater in WHEY compared with the WC10 and WC15 treatments (p <.05). Plasma glycine and nonessential amino acid concentrations declined following whey protein ingestion but increased following collagen coingestion (p <.05). Postprandial plasma glycine availability averaged −8.9 ± 5.8, 9.2 ± 3.7, 23.1 ± 6.5, and 39.8 ± 11.0 mmol·360 min/L in WHEY, WC05, WC10, and WC15, respectively (incremental area under curve values, p <.05). Coingestion of a small amount of collagen (5 g) with whey protein (25 g) is sufficient to prevent the decline in plasma glycine availability during recovery from lower body resistance-type exercise in recreationally active men. [ABSTRACT FROM AUTHOR]

The present study assessed whether single-leg daily blood flow restriction (BFR) treatment attenuates the decline in muscle fiber size, capillarization, and satellite cell (SC) content during 2 wk of bed rest in healthy, young men. Twelve healthy, young men (age: 24 ± 3 yr; BMI: 23.7 ± 3.1 kg/m2) were subjected to 2 wk of bed rest, during which one leg was exposed to three times daily 5 min of BFR, whereas the contralateral leg received sham treatment [control (CON)]. Muscle biopsies were obtained from the m. vastus lateralis from both the BFR and CON legs before and immediately after 2 wk of bed rest. Types I and II muscle fiber size, myonuclear content, capillarization, and SC content were assessed by immunohistochemistry. No significant decline in either type I or type II muscle fiber size was observed following bed rest, with no differences between the CON and BFR legs (P > 0.05). Type I muscle fiber capillary density increased in response to bed rest in both legs (P < 0.05), whereas other muscle fiber capillarization measures remained unaltered. SC content decreased in both type I (from 7.4 ± 3.2 to 5.9 ± 2.7 per 100 fibers) and type II (from 7.2 ± 3.4 to 6.5 ± 3.2 per 100 fibers) muscle fibers (main effect of time P = 0.018), with no significant differences between the BFR and CON legs (P > 0.05). In conclusion, 2 wk of bed rest has no effect on muscle capillarization and decreases the SC content, and daily BFR treatment does not affect skeletal muscle fiber size and SC content in healthy, young men. NEW & NOTEWORTHY: We recently reported that the application of daily blood flow restriction (BFR) treatment does not preserve muscle mass or strength and does not modulate daily muscle protein synthesis rates during 2 wk of bed rest. Here, we show that 2 wk of bed rest resulted in a decrease in satellite cell (SC) content. In addition, the BFR treatment did not affect muscle fiber size, capillarization, and SC content during 2 wk of bed rest. [ABSTRACT FROM AUTHOR]

Prolonged passive heat treatment (PHT) has been suggested to trigger skeletal muscle adaptations that may improve muscle maintenance in older individuals. To assess the effects of PHT on skeletal muscle tissue capillarization, perfusion capacity, protein synthesis rates, hypertrophy and leg strength, 14 older adults (9 males, 5 females; 73 ± 6 years) underwent 8 weeks of PHT (infrared sauna: 3× per week, 45 min at ∼60°C). Before and after PHT we collected muscle biopsies to assess skeletal muscle capillarization and fibre cross‐sectional area (CSA). Basal and postprandial muscle tissue perfusion kinetics and protein synthesis rates were assessed using contrast‐enhanced ultrasound and primed continuous l‐[ring‐13C6]phenylalanine infusions, respectively. One‐repetition maximum (1RM) leg strength and vastus lateralis muscle CSA were assessed. Type I and type II muscle fibre capillarization strongly increased following PHT (capillary‐to‐fibre perimeter exchange index: +31 ± 18 and +33 ± 30%, respectively; P < 0.001). No changes were observed in basal (0.24 ± 0.27 vs. 0.18 ± 0.11 AU; P = 0.266) or postprandial (0.20 ± 0.12 vs. 0.18 ± 0.14 AU; P = 0.717) microvascular blood flow following PHT. Basal (0.048 ± 0.014 vs. 0.051 ± 0.019%/h; P = 0.630) and postprandial (0.041 ± 0.012 vs. 0.051 ± 0.024%/h; P = 0.199) muscle protein synthesis rates did not change in response to prolonged PHT. Furthermore, no changes in vastus lateralis muscle CSA (15.3 ± 4.6 vs. 15.2 ± 4.6 cm2; P = 0.768) or 1RM leg strength (46 ± 12 vs. 47 ± 12 kg; P = 0.087) were observed over time. In conclusion, prolonged PHT increases muscle tissue capillarization but this does not improve muscle microvascular blood flow or increase muscle protein synthesis rates in healthy, older adults. Prolonged PHT does not induce skeletal muscle hypertrophy or increase leg strength in healthy, older adults. Key points: Repeated exposure to heat has been suggested to trigger skeletal muscle adaptive responses.We investigated the effect of 8 weeks of whole‐body passive heat treatment (PHT; infrared sauna: 3× per week for 45 min at ∼60°C) on skeletal muscle tissue capillarization, perfusion capacity, basal, and postprandial muscle protein synthesis rates, muscle (fibre) hypertrophy, and leg strength in healthy, older adults.Prolonged PHT increases muscle tissue capillarization, but this does not improve muscle microvascular blood flow or increase muscle protein synthesis rates.Despite increases in muscle tissue capillarization, prolonged PHT does not suffice to induce skeletal muscle hypertrophy or increase leg strength in healthy, older adults. [ABSTRACT FROM AUTHOR]

Introduction Passive heat treatment has been suggested to improve glycemic control in individuals with type 2 diabetes mellitus (T2DM). Previous studies have focused predominantly on hot water immersion and traditional sauna bathing, as opposed to the more novel method of infrared-based sauna bathing. Here, the impact of a single infrared sauna session on post-prandial glycemic control was assessed in older individuals with T2DM. Methods In this randomized controlled crossover trial, 12 participants with T2DM (male/female: 10/2, age: 69±7 y, BMI: 27.5±2.9 kg/m2) rested in an infrared sauna twice: once in a heated (60°C) and once in a thermoneutral (21°C) condition for 40 min, immediately followed by a 2-h oral glucose tolerance test (OGTT). Venous blood samples were obtained to assess plasma glucose and insulin concentrations and to determine the whole-body composite insulin sensitivity index. Results Body core and leg skin temperature were higher following the heated condition compared to the thermoneutral condition (38.0±0.3 vs. 36.6±0.2°C and 39.4±0.8 vs. 31.3±0.8°C, respectively; P<0.001 for both). The incremental area under the curve (iAUC) of plasma glucose concentrations during the OGTT was higher after the heated condition compared to the thermoneutral condition (17.7±3.1 vs. 14.8±2.8 mmol/L/120 min; P<0.001). No differences were observed in plasma insulin concentrations (heated: 380±194 vs. thermoneutral: 376±210 pmol/L/120 min; P=0.93) or whole-body composite insulin sensitivity indexes (4.5±2.8 vs. 4.5±2.1; P=0.67). Conclusions A single infrared sauna session does not improve postprandial blood glucose handling in individuals with T2DM. Future studies should assess the effect of more prolonged application of infrared sauna bathing on daily glycemic control. [ABSTRACT FROM AUTHOR]

Introduction: Microvascular perfusion is essential for post-exercise skeletal muscle recovery to ensure adequate delivery of nutrients and growth factors. This study assessed the relationship between various indices of muscle fiber capillarization and microvascular perfusion assessed by contrast-enhanced ultrasound (CEUS) at rest and during recovery from a bout of resistance exercise in older adults. Methods: Sixteen older adults (72 ± 6 y, 5/11 male/female) participated in an experimental test day during which a muscle biopsy was collected from the vastus lateralis and microvascular perfusion was determined by CEUS at rest and at 10 and 40 min following a bout of resistance exercise. Immunohistochemistry was performed on muscle tissue samples to determine various indices of both mixed and fiber-type-specific muscle fiber capillarization. Results: Microvascular blood volume at t = 10 min was higher compared with rest and t = 40 min (27.2 ± 4.7 vs. 3.9 ± 4.0 and 7.0 ± 4.9 AU, respectively, both p < 0.001). Microvascular blood volume at t = 40 min was higher compared with rest (p < 0.001). No associations were observed between different indices of mixed muscle fiber capillarization and microvascular blood volume at rest and following exercise. A moderate (r = 0.59, p < 0.05) and strong (r = 0.81, p < 0.001) correlation was observed between type II muscle fiber capillary-to-fiber ratio and the microvascular blood volume increase from rest to t = 10 and t = 40 min, respectively. In addition, type II muscle fiber capillary contacts and capillary-to-fiber perimeter exchange index were strongly correlated with the microvascular blood volume increase from rest to t = 40 min (r = 0.66, p < 0.01 and r = 0.64, p < 0.01, respectively). Conclusion: Resistance exercise strongly increases microvascular blood volume for at least 40 min after exercise cessation in older adults. This resistance exercise-induced increase in microvascular blood volume is strongly associated with type II muscle fiber capillarization in older adults. [ABSTRACT FROM AUTHOR]

Pompe disease is an inherited metabolic myopathy caused by deficiency of acid alpha‐glucosidase (GAA), resulting in lysosomal glycogen accumulation. Residual GAA enzyme activity affects disease onset and severity, although other factors, including dysregulation of cytoplasmic glycogen metabolism, are suspected to modulate the disease course. In this study, performed in mice and patient biopsies, we found elevated protein levels of enzymes involved in glucose uptake and cytoplasmic glycogen synthesis in skeletal muscle from mice with Pompe disease, including glycogenin (GYG1), glycogen synthase (GYS1), glucose transporter 4 (GLUT4), glycogen branching enzyme 1 (GBE1), and UDP‐glucose pyrophosphorylase (UGP2). Expression levels were elevated before the loss of muscle mass and function. For first time, quantitative mass spectrometry in skeletal muscle biopsies from five adult patients with Pompe disease showed increased expression of GBE1 protein relative to healthy controls at the group level. Paired analysis of individual patients who responded well to treatment with enzyme replacement therapy (ERT) showed reduction of GYS1, GYG1, and GBE1 in all patients after start of ERT compared to baseline. These results indicate that metabolic changes precede muscle wasting in Pompe disease, and imply a positive feedforward loop in Pompe disease, in which lysosomal glycogen accumulation promotes cytoplasmic glycogen synthesis and glucose uptake, resulting in aggravation of the disease phenotype. [ABSTRACT FROM AUTHOR]

Background Plant-derived proteins are considered to have lesser anabolic properties when compared with animal-derived proteins. The attenuated rise in muscle protein synthesis rates following ingestion of plant-derived compared with animal-derived protein has been, at least partly, attributed to deficiencies in specific amino acids such as leucine, lysine, and/or methionine. Combining different plant-derived proteins could provide plant-derived protein blends with a more balanced amino acid profile. Objectives This study aimed to compare postprandial muscle protein synthesis rates following the ingestion of 30 g milk protein with a 30 g blend combining wheat, corn, and pea protein in healthy young men. Methods In a randomized, double-blind, parallel-group design, 24 young males (aged 24 ± 4 y) received a primed continuous l -[ring-13C6]-phenylalanine infusion after which they ingested 30 g milk protein (MILK) or a 30 g plant-derived protein blend combining 15 g wheat, 7.5 g corn, and 7.5 g pea protein (PLANT-BLEND). Blood and muscle biopsies were collected frequently for 5 h to assess postprandial plasma amino acid profiles (secondary outcome) and subsequent muscle protein synthesis rates (primary outcome). Data were analyzed by 2-factor repeated measures ANOVA and 2-samples t tests. Results MILK increased plasma essential amino acid concentrations more than PLANT-BLEND over the 5 h postprandial period (incremental AUC = 151 ± 31 compared with 79 ± 12 mmol·300 min·L−1, respectively; P  < 0.001). Ingestion of both MILK and PLANT-BLEND increased myofibrillar protein synthesis rates (P  < 0.001), with no significant differences between treatments (0.053 ± 0.013%/h and 0.064 ± 0.016%/h, respectively; P  = 0.08). Conclusions Ingestion of 30 g plant-derived protein blend combining wheat-, corn-, and pea-derived protein increases muscle protein synthesis rates in healthy young males. The muscle protein synthetic response to the ingestion of 30 g of this plant-derived protein blend does not differ from the ingestion of an equivalent amount of a high-quality animal-derived protein. Clinical trial registry number for Nederlands Trial Register: NTR6548 (https://trialsearch.who.int/Trial2.aspx?TrialID=NTR6548). [ABSTRACT FROM AUTHOR]

Plant-based proteins are considered to be less effective in their capacity to stimulate muscle protein synthesis when compared with animal-based protein sources, likely due to differences in amino acid contents. We compared the postprandial muscle protein synthetic response following the ingestion of a lysine-enriched plant-based protein product with an isonitrogenous amount of chicken. Twenty-four men (age 24 ± 5 years; BMI 22·9 ± 2·6 kg·m−2) participated in this parallel, double-blind, randomised controlled trial and consumed 40 g of protein as a lysine-enriched wheat and chickpea protein product (Plant, n 12) or chicken breast fillet (Chicken, n 12). Primed, continuous intravenous l-(ring-13C6)-phenylalanine infusions were applied while repeated blood and muscle samples were collected over a 5-h postprandial period to assess plasma amino acid responses, muscle protein synthesis rates and muscle anabolic signalling responses. Postprandial plasma leucine and essential amino acid concentrations were higher following Chicken (P < 0·001), while plasma lysine concentrations were higher throughout in Plant (P < 0·001). Total plasma amino acid concentrations did not differ between interventions (P = 0·181). Ingestion of both Plant and Chicken increased muscle protein synthesis rates from post-absorptive: 0·031 ± 0·011 and 0·031 ± 0·013 to postprandial: 0·046 ± 0·010 and 0·055 ± 0·015 % h−1, respectively (P -time < 0·001), with no differences between Plant and Chicken (time x treatment P = 0·068). Ingestion of 40 g of protein in the form of a lysine-enriched plant-based protein product increases muscle protein synthesis rates to a similar extent as an isonitrogenous amount of chicken in healthy, young men. Plant-based protein products sold as meat replacers may be as effective as animal-based protein sources to stimulate postprandial muscle protein synthesis rates in healthy, young individuals. [ABSTRACT FROM AUTHOR]