Assessing Muscle Protein Synthesis Rates In Vivo in Humans: The Deuterated Water (HO) Method.

Skeletal muscle tissue is in a constant state of turnover, with muscle tissue protein synthesis and breakdown rates ranging between 1% and 2% across the day in vivo in humans. Muscle tissue remodeling is largely controlled by the up- and down-regulation of muscle tissue protein synthesis rates. Research studies generally apply stable isotope-labeled amino acids to assess muscle protein synthesis rates in vivo in humans.

A Single Sauna Session Does Not Improve Postprandial Blood Glucose Handling in Individuals with Type 2 Diabetes Mellitus: A Cross-Over, Randomized, Controlled Trial.

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.

Administration of Free Amino Acids Improves Exogenous Amino Acid Availability when Compared with Intact Protein in Critically Ill Patients: A Randomized Controlled Study.

Background: Protein digestion and amino acid absorption appear compromised in critical illness. The provision of enteral feeds with free amino acids rather than intact protein may improve postprandial amino acid availability.

Objective: Our objective was to quantify the uptake of diet-derived phenylalanine after the enteral administration of intact protein compared with an equivalent amount of free amino acids in critically ill patients.

Graded Replacement of Carbohydrate-Rich Breakfast Products with Dairy Products: Effects on Postprandial Aminoacidemia, Glycemic Control, Bone Metabolism, and Satiety.

Background: Postprandial metabolic responses following dairy consumption have mostly been studied using stand-alone dairy products or milk-derived nutrients.

Objective: Assessing the impact of ingesting dairy products as part of a common breakfast on postprandial aminoacidemia, glycemic control, markers of bone metabolism, and satiety.

Methods: In this randomized, crossover study, 20 healthy young males and females consumed on 3 separate occasions an iso-energetic breakfast containing no dairy (NO-D), 1 dairy (ONE-D), or 2 dairy (TWO-D) products.

Higher Muscle Protein Synthesis Rates Following Ingestion of an Omnivorous Meal Compared with an Isocaloric and Isonitrogenous Vegan Meal in Healthy, Older Adults.

Background: Plant-derived proteins are considered to have fewer anabolic properties when compared with animal-derived proteins. The anabolic properties of isolated proteins do not necessarily reflect the anabolic response to the ingestion of whole foods. The presence or absence of the various components that constitute the whole-food matrix can strongly impact protein digestion and amino acid absorption and, as such, modulate postprandial muscle protein synthesis rates.

Acute Quark Ingestion Increases Muscle Protein Synthesis Rates at Rest with a Further Increase after Exercise in Young and Older Adult Males in a Parallel-Group Intervention Trial.

Background: Ingestion of protein concentrates or isolates increases muscle protein synthesis rates in young and older adults. There is far less information available on the anabolic response following the ingestion of dairy wholefoods, which are commonly consumed in a normal diet.

Objectives: This study investigates whether ingestion of 30 g protein provided as quark increases muscle protein synthesis rates at rest and whether muscle protein synthesis rates are further increased after resistance exercise in young and older adult males.

The effect of minimally invasive surgical aortic valve replacement on postoperative pulmonary and skeletal muscle function.

New Findings: What is the central question of this study? How does surgical aortic valve replacement affect cardiopulmonary and muscle function during exercise? What is the main finding and its importance? Early after the surgical replacement of the aortic valve a significant decline in pulmonary function was observed, which was followed by a decline in skeletal muscle function in the subsequent weeks of recovery. These date reiterate, despite restoration of aortic valve function, the need for a tailored rehabilitation programme for the respiratory and peripheral muscular system.

Abstract: Suboptimal post-operative improvements in functional capacity are often observed after minimally invasive aortic valve replacement (mini-AVR).

Protein Ingestion before Sleep Increases Overnight Muscle Protein Synthesis Rates in Healthy Older Men: A Randomized Controlled Trial.

The loss of skeletal muscle mass with aging has been attributed to the blunted anabolic response to protein intake. Presleep protein ingestion has been suggested as an effective strategy to compensate for such anabolic resistance. We assessed the efficacy of presleep protein ingestion on dietary protein digestion and absorption kinetics and overnight muscle protein synthesis rates in older men.

Glucose Plus Fructose Ingestion for Post-Exercise Recovery-Greater than the Sum of Its Parts?

Carbohydrate availability in the form of muscle and liver glycogen is an important determinant of performance during prolonged bouts of moderate- to high-intensity exercise. Therefore, when effective endurance performance is an objective on multiple occasions within a 24-h period, the restoration of endogenous glycogen stores is the principal factor determining recovery. This review considers the role of glucose-fructose co-ingestion on liver and muscle glycogen repletion following prolonged exercise.

Beetroot Juice Supplementation Improves High-Intensity Intermittent Type Exercise Performance in Trained Soccer Players.

It has been shown that nitrate supplementation can enhance endurance exercise performance. Recent work suggests that nitrate ingestion can also increase intermittent type exercise performance in recreational athletes. We hypothesized that six days of nitrate supplementation can improve high-intensity intermittent type exercise performance in trained soccer players.

Fructose and Sucrose Intake Increase Exogenous Carbohydrate Oxidation during Exercise.

Peak exogenous carbohydrate oxidation rates typically reach ~1 g∙min-1 during exercise when ample glucose or glucose polymers are ingested. Fructose co-ingestion has been shown to further increase exogenous carbohydrate oxidation rates. The purpose of this study was to assess the impact of fructose co-ingestion provided either as a monosaccharide or as part of the disaccharide sucrose on exogenous carbohydrate oxidation rates during prolonged exercise in trained cyclists.

Dietary nitrate does not reduce oxygen cost of exercise or improve muscle mitochondrial function in patients with mitochondrial myopathy.

Muscle weakness and exercise intolerance negatively affect the quality of life of patients with mitochondrial myopathy. Short-term dietary nitrate supplementation has been shown to improve exercise performance and reduce oxygen cost of exercise in healthy humans and trained athletes. We investigated whether 1 wk of dietary inorganic nitrate supplementation decreases the oxygen cost of exercise and improves mitochondrial function in patients with mitochondrial myopathy.

Pre-Sleep Protein Ingestion to Improve the Skeletal Muscle Adaptive Response to Exercise Training.

Protein ingestion following resistance-type exercise stimulates muscle protein synthesis rates, and enhances the skeletal muscle adaptive response to prolonged resistance-type exercise training. As the adaptive response to a single bout of resistance exercise extends well beyond the first couple of hours of post-exercise recovery, recent studies have begun to investigate the impact of the timing and distribution of protein ingestion during more prolonged recovery periods. Recent work has shown that overnight muscle protein synthesis rates are restricted by the level of amino acid availability.

Habituation to low or high protein intake does not modulate basal or postprandial muscle protein synthesis rates: a randomized trial.

Background: Muscle mass maintenance is largely regulated by basal muscle protein synthesis rates and the ability to increase muscle protein synthesis after protein ingestion. To our knowledge, no previous studies have evaluated the impact of habituation to either low protein intake (LOW PRO) or high protein intake (HIGH PRO) on the postprandial muscle protein synthetic response.

Objective: We assessed the impact of LOW PRO compared with HIGH PRO on basal and postprandial muscle protein synthesis rates after the ingestion of 25 g whey protein.

Muscle fibre capillarization is a critical factor in muscle fibre hypertrophy during resistance exercise training in older men.

Background: Adequate muscle fibre perfusion is critical for the maintenance of muscle mass; it is essential in the rapid delivery of oxygen, nutrients and growth factors to the muscle, stimulating muscle fibre growth. Muscle fibre capillarization is known to decrease substantially with advancing age. However, whether (relative) low muscle fibre capillarization negatively impacts the muscle hypertrophic response following resistance exercise training in older adults is unknown.

Increasing Insulin Availability Does Not Augment Postprandial Muscle Protein Synthesis Rates in Healthy Young and Older Men.

Context: Skeletal muscle protein synthesis is highly responsive to food intake. It has been suggested that the postprandial increase in circulating insulin modulates the muscle protein synthetic response to feeding.

Objective: The objective of the study was to investigate whether a greater postprandial rise in circulating insulin level increases amino acid uptake in muscle and augments postprandial muscle protein synthesis rates.

Neuromuscular electrical stimulation prior to presleep protein feeding stimulates the use of protein-derived amino acids for overnight muscle protein synthesis.

Unlabelled: Short periods of muscle disuse result in substantial skeletal muscle atrophy. Recently, we showed that both neuromuscular electrical stimulation (NMES) as well as presleep dietary protein ingestion represent effective strategies to stimulate muscle protein synthesis rates. In this study, we test our hypothesis that NMES can augment the use of presleep protein-derived amino acids for overnight muscle protein synthesis in older men.

Presleep protein ingestion does not compromise the muscle protein synthetic response to protein ingested the following morning.

Protein ingestion before sleep augments postexercise muscle protein synthesis during overnight recovery. It is unknown whether postexercise and presleep protein consumption modulates postprandial protein handling and myofibrillar protein synthetic responses the following morning. Sixteen healthy young (24 ± 1 yr) men performed unilateral resistance-type exercise (contralateral leg acting as a resting control) at 2000.

Habitual Dietary Nitrate Intake in Highly Trained Athletes.

Although beetroot juice, as a nitrate carrier, is a popular ergogenic supplement among athletes, nitrate is consumed through the regular diet as well. We aimed to assess the habitual dietary nitrate intake and identify the main contributing food sources in a large group of highly trained athletes. Dutch highly trained athletes (226 women and 327 men) completed 2-4 web-based 24-hr dietary recalls and questionnaires within a 2- to 4-week period.

Resistance Training Increases Skeletal Muscle Capillarization in Healthy Older Men.

Purpose: Skeletal muscle capillarization plays a key role in oxygen and nutrient delivery to muscle. The loss of muscle mass with aging and the concept of anabolic resistance have been, at least partly, attributed to changes in skeletal muscle capillary structure and function. We aimed to compare skeletal muscle capillarization between young and older men and evaluate whether resistance-type exercise training increases muscle capillarization in older men.

Dietary Protein Intake and Distribution Patterns of Well-Trained Dutch Athletes.

Dietary protein intake should be optimized in all athletes to ensure proper recovery and enhance the skeletal muscle adaptive response to exercise training. In addition to total protein intake, the use of specific proteincontaining food sources and the distribution of protein throughout the day are relevant for optimizing protein intake in athletes. In the present study, we examined the daily intake and distribution of various proteincontaining food sources in a large cohort of strength, endurance and team-sport athletes.

Diurnal Rhythm of Cardiac Troponin: Consequences for the Diagnosis of Acute Myocardial Infarction.

Background: Interpretation of serial high-sensitivity cardiac troponin (hs-cTn) measurements for the diagnosis of acute myocardial infarction (AMI) assumes random fluctuation of hs-cTn around an individual's homeostatic set point. The aim of this study was to challenge this diagnostic concept.

Methods: Study 1 examined the presence of a diurnal hs-cTn rhythm by hourly blood sampling, day and night, in 24 individuals without a recent history of AMI.

Resistance Exercise Augments Postprandial Overnight Muscle Protein Synthesis Rates.

Introduction: We have previously shown that protein ingestion before sleep increases overnight muscle protein synthesis rates. Whether prior exercise further augments the muscle protein synthetic response to presleep protein ingestion remains to be established.

Objective: This study aimed to assess whether resistance-type exercise performed in the evening increases the overnight muscle protein synthetic response to presleep protein ingestion.