Publications by authors named "Stephens F"

Optimal adaptation to resistance exercise requires maximal rates of myofibrillar protein synthesis (MyoPS), which can be achieved by postexercise consumption of >20 g of protein or ∼2 g of the essential amino acid (EAA) leucine. These nutritional recommendations are based on studies in males. The aim of the present study was to compare the postexercise MyoPS response to nutrition in young females.

View Article and Find Full Text PDF

Introduction: Microalgae provide a sustainable basis for protein-rich food production. However, human data concerning microalgae ingestion, subsequent postprandial amino acid (AA) availability and associated metabolic responses are minimal.

Objectives: We investigated ingesting sp.

View Article and Find Full Text PDF

We characterized daily dietary protein intakes, focusing on protein source (animal and nonanimal) and form (whole-foods and supplemental) in young (18-40 years) resistance trained (training ≥ 3×/week for ≥ 6 months; TRA; male, n = 30; female, n = 14) and recreationally active (no structured training; REC; male, n = 30; female, n = 30) individuals. Using 3-day weighed food diaries from 10 previous studies, we assessed macronutrient intakes using dietary analysis software. Energy intakes trended greater in TRA compared with REC (p = .

View Article and Find Full Text PDF

Background: High-protein diets have been recognized as a potential strategy in the nutritional management of type 2 diabetes (T2D). Mycoprotein is a high-fibre, high-protein food ingredient previously shown to improve acute glycaemic control. We determined whether incorporating mycoprotein into a high-protein vegan diet would improve glycaemic control to a greater extent than an isonitrogenous omnivorous diet in people with T2D.

View Article and Find Full Text PDF

Introduction: The reduction in sex hormone production across the menopause transition is thought to accelerate age-related decline in muscle mass, strength, and stability, increasing the risk of falls and fractures. We aimed to investigate whether a novel low-impact resistance exercise program could improve strength, balance, and body composition and whether any improvement was affected by menopause status.

Methods: Seventy healthy, moderately active pre- (PRE; 46.

View Article and Find Full Text PDF

It is not clear if fat oxidation is attenuated at higher exercise intensities, when exercising with a small muscle mass, and therefore, we studied leg fat oxidation during graded one-leg exercise. Ten males (age: 27 ± 2 years, body mass: 82 ± 3 kg, BMI: 24 ± 1 kg m, V̇O: 49 ± 2 mL min kg) performed one-leg exercise at 25% of maximal workload (W) for 30 min, followed by 120-min exercise at 55% W with the contralateral leg, and finally 30-min exercise at 85% W with the first leg. Blood was sampled from an artery and both femoral veins, and blood flow was determined using Doppler ultrasound.

View Article and Find Full Text PDF

Background: Mycoprotein is a high-fibre food previously shown to reduce postprandial glucose concentrations when ingested within a mixed-meal. We applied a dual stable isotope tracer approach to determine whether this is due to a reduced rate of appearance of glucose, in participants of ranging BMI.

Methods: Twenty-four adults (F = 8, BMI 30 ± 6 kg·m) attended 2 trials in a double-blind, randomised, cross-over design.

View Article and Find Full Text PDF

Background: Industrial processing can alter the structural complexity of dietary proteins and, potentially, their digestion and absorption upon ingestion. High-moisture extrusion (HME), a common processing method used to produce meat alternative products, affects in vitro digestion, but human data are lacking. We hypothesized that HME of a mycoprotein/pea protein blend would impair in vitro digestion and in vivo postprandial plasma amino acid availability.

View Article and Find Full Text PDF

The regulation of postprandial muscle protein synthesis (MPS) with or without physical activity has been an intensely studied area within nutrition and physiology. The leucine content of dietary protein and the subsequent plasma leucinemia it elicits postingestion is often considered the primary drivers of the postprandial MPS response. This concept, generally known as the leucine "trigger" hypothesis, has also been adopted within more applied aspects of nutrition.

View Article and Find Full Text PDF
Article Synopsis
  • - The study explores the effectiveness of a new plant-based protein blend compared to whey protein in promoting myofibrillar protein synthesis (MyoPS) after resistance exercise, given that plant proteins typically have less favorable amino acid profiles.
  • - Ten resistance-trained young adults participated in a double-blind trial where they underwent leg exercises and ingested either whey protein or the plant blend, with blood and muscle samples collected to assess amino acid levels and MyoPS rates over several hours.
  • - Results showed that while plasma essential amino acid levels were higher after whey protein ingestion, the MyoPS rates after exercising and consuming either protein source were nearly identical, indicating the plant blend can be as effective as whey for muscle synthesis post-exercise
View Article and Find Full Text PDF

Aims/hypothesis: The aim of the present study was to conduct a randomised, placebo-controlled, double-blind, crossover trial to determine whether pre-meal ketone monoester ingestion reduces postprandial glucose concentrations in individuals with type 2 diabetes.

Methods: In this double-blind, placebo-controlled, crossover design study, ten participants with type 2 diabetes (age 59±1.7 years, 50% female, BMI 32±1 kg/m, HbA 54±2 mmol/mol [7.

View Article and Find Full Text PDF
Article Synopsis
  • * Results showed a significant decline in insulin-stimulated leg glucose uptake and leg muscle volume after bed-rest, along with reduced myofibrillar protein synthesis and decreased muscle glycogen storage.
  • * After reintroducing exercise (short-term exercise-supplemented remobilization), the study aimed to assess potential improvements in muscle volume, protein turnover, and glucose uptake, but the effects of this remobilization were not detailed.
View Article and Find Full Text PDF

Background: Substituting dietary meat and fish for mycoprotein, a fungal-derived food source rich in protein and fibre, decreases circulating cholesterol concentrations in laboratory-controlled studies. However, whether these findings can be translated to a home-based setting, and to decrease cholesterol concentrations in overweight and hypercholesterolemic individuals, remains to be established.

Objective: We investigated whether a remotely-delivered, home-based dietary intervention of mycoprotein-containing food products would affect various circulating cholesterol moieties and other markers of cardio-metabolic health in overweight (BMI >27.

View Article and Find Full Text PDF

Although the mechanisms underpinning short-term muscle disuse atrophy and associated insulin resistance remain to be elucidated, perturbed lipid metabolism might be involved. Our aim was to determine the impact of acipimox administration [i.e.

View Article and Find Full Text PDF

Whole-body tissue protein turnover is regulated, in part, by the postprandial rise in plasma amino acid concentrations, although minimal data exist on the amino acid response following non-animal-derived protein consumption. We hypothesised that the ingestion of novel plant- and algae-derived dietary protein sources would elicit divergent plasma amino acid responses when compared with vegan- and animal-derived control proteins. Twelve healthy young (male (m)/female (f): 6/6; age: 22 ± 1 years) and 10 healthy older (m/f: 5/5; age: 69 ± 2 years) adults participated in a randomised, double-blind, cross-over trial.

View Article and Find Full Text PDF

Nasogastric feeding of protein-rich liquids is a nutritional support therapy that attenuates muscle mass loss. However, whether administration via a nasogastric tube per se augments whole-body or muscle protein anabolism compared with oral administration is unknown. Healthy participants were administered a protein-rich drink (225 ml containing 21 g protein) orally (ORAL; n=13; age 21 ± 1 year; BMI 22.

View Article and Find Full Text PDF

Studies of extreme endurance have suggested that there is an alimentary limit to energy intake (EI) of ∼2.5 × resting metabolic rate (RMR). To gain further insight, this study aimed to simultaneously measure EI, total energy expenditure (TEE) body mass and muscle mass in a large cohort of males and females of varying ages during a transatlantic rowing race.

View Article and Find Full Text PDF

Background: Critically ill patients suffer from acute muscle wasting, which is associated with significant physical functional impairment. We describe data from nested muscle biopsy studies from two trials of functional electrical stimulation (FES) that did not shown improvements in physical function.

Methods: Primary cohort: single-centre randomized controlled trial.

View Article and Find Full Text PDF

The mechanisms underpinning short-term muscle disuse atrophy remain to be elucidated, but perturbations in lipid metabolism may be involved. Specifically, positive muscle non-esterified fatty acid (NEFA) balance has been implicated in the development of disuse-induced insulin and anabolic resistance. Our aim was to determine the impact of acipimox administration (i.

View Article and Find Full Text PDF

Myostatin negatively regulates skeletal muscle growth and appears upregulated in human obesity and associated with insulin resistance. However, observations are confounded by ageing, and the mechanisms responsible are unknown. The aim of this study was to delineate between the effects of excess adiposity, insulin resistance and ageing on myostatin mRNA expression in human skeletal muscle and to investigate causative factors using in vitro models.

View Article and Find Full Text PDF

Background: Spirulina [SPIR] (cyanobacterium) and chlorella [CHLO] (microalgae) are foods rich in protein and essential amino acids; however, their capacity to stimulate myofibrillar protein synthesis (MyoPS) in humans remains unknown.

Objectives: We assessed the impact of ingesting SPIR and CHLO compared with an established high-quality nonanimal-derived dietary protein source (fungal-derived mycoprotein [MYCO]) on plasma amino acid concentrations, as well as resting and postexercise MyoPS rates in young adults.

Methods: Thirty-six healthy young adults (age: 22 ± 3 y; BMI: 23 ± 3 kg·m; male [m]/female [f], 18/18) participated in a randomized, double-blind, parallel-group trial.

View Article and Find Full Text PDF

Background: Dietary protein ingestion augments post (resistance) exercise muscle protein synthesis (MPS) rates. It is thought that the dose of leucine ingested within the protein (leucine threshold hypothesis) and the subsequent plasma leucine variables (leucine trigger hypothesis; peak magnitude, rate of rise, and total availability) determine the magnitude of the postprandial postexercise MPS response.

Methods: A quantitative systematic review was performed extracting data from studies that recruited healthy adults, applied a bout of resistance exercise, ingested a bolus of protein within an hour of exercise, and measured plasma leucine concentrations and MPS rates (delta change from basal).

View Article and Find Full Text PDF

Pea protein is an attractive nonanimal-derived protein source to support dietary protein requirements. However, although high in leucine, a low methionine content has been suggested to limit its anabolic potential. Mycoprotein has a complete amino acid profile which, at least in part, may explain its ability to robustly stimulate myofibrillar protein synthesis (MyoPS) rates.

View Article and Find Full Text PDF

Background: The decline in postabsorptive and postprandial muscle protein fractional synthesis rates (FSR) does not quantitatively account for muscle atrophy during uncomplicated, short-term disuse, when atrophy rates are the highest. We sought to determine whether 2 days of unilateral knee immobilization affects mixed muscle protein fractional breakdown rates (FBR) during postabsorptive and simulated postprandial conditions.

Methods: Twenty-three healthy, male participants (age: 22 ± 1 year; height: 179 ± 1 cm; body mass: 73.

View Article and Find Full Text PDF