A majority of human genes produce non-protein-coding RNA (ncRNA), and some have roles in development and disease. Neither ncRNA nor human skeletal muscle is ideally studied using short-read sequencing, so we used a customized RNA pipeline and network modelling to study cell-type specific ncRNA responses during muscle growth at scale. We completed five human resistance-training studies ( = 144 subjects), identifying 61% who successfully accrued muscle-mass.
View Article and Find Full Text PDFBackground: Essential amino acid (EAA) and omega-3 fatty acid ingestion independently attenuate leg skeletal muscle disuse atrophy in uninjured persons. However, no data exist regarding the effectiveness of combined EAA and omega-3 fatty acid ingestion to mitigate skeletal muscle disuse atrophy in response to anterior cruciate ligament reconstruction (ACLR) surgery. This pilot trial will explore the feasibility of recruitment and retention of ACLR outpatients from a single center across 18 months to consume either a combination of omega-3 fatty acids and EAAs, or a placebo control, for 4 weeks before and 2 weeks after surgery.
View Article and Find Full Text PDFA majority of human genes produce non-protein-coding RNA (ncRNA), and some have roles in development and disease. Neither ncRNA nor human skeletal muscle is ideally studied using short-read sequencing, so we used a customised RNA pipeline and network modelling to study cell-type specific ncRNA responses during muscle growth at scale. We completed five human resistance-training studies (n=144 subjects), identifying 61% who successfully accrued muscle-mass.
View Article and Find Full Text PDFAerobic and resistance exercise (RE) induce distinct molecular responses. One hypothesis is that these responses are antagonistic and unfavorable for the anabolic response to RE when concurrent exercise is performed. This thesis may also depend on the participants' training status and concurrent exercise order.
View Article and Find Full Text PDFSequencing the human genome empowers translational medicine, facilitating transcriptome-wide molecular diagnosis, pathway biology, and drug repositioning. Initially, microarrays are used to study the bulk transcriptome; but now short-read RNA sequencing (RNA-seq) predominates. Positioned as a superior technology, that makes the discovery of novel transcripts routine, most RNA-seq analyses are in fact modeled on the known transcriptome.
View Article and Find Full Text PDFBackground: We determined the short-term (i.e. 4 days) impacts of disuse atrophy in relation to muscle protein turnover [acute fasted-fed muscle protein synthesis (MPS)/muscle protein breakdown (MPB) and integrated MPS/estimated MPB].
View Article and Find Full Text PDFDecreased skeletal muscle contractile activity (disuse) or unloading leads to muscle mass loss, also known as muscle atrophy. The balance between muscle protein synthesis (MPS) and muscle protein breakdown (MPB) is the primary determinant of skeletal muscle mass. A reduced mechanical load on skeletal muscle is one of the main external factors leading to muscle atrophy.
View Article and Find Full Text PDFBackground: The stimulation of muscle protein synthesis (MPS) by dietary protein is reduced with age. We hypothesized that twice-daily milk consumption would increase daily rates of MPS in older women relative to a nondairy milk alternative and that MPS would be enhanced by increased physical activity (PA).
Methods: Twenty-two older women were randomly assigned to 1 of 3 experimental groups: whole milk (WM; n = 7, 69 ± 3 y), skim milk (SM; n = 7, 68 ± 3 y), or an almond beverage (AB; n = 8, 63 ± 3 y).
Muscle disuse leads to a rapid decline in muscle mass, with reduced muscle protein synthesis (MPS) considered the primary physiological mechanism. Here, we employed a systems biology approach to uncover molecular networks and key molecular candidates that quantitatively link to the degree of muscle atrophy and/or extent of decline in MPS during short-term disuse in humans. After consuming a bolus dose of deuterium oxide (D O; 3 mL.
View Article and Find Full Text PDFSkeletal muscle is the organ of locomotion, its optimal function is critical for athletic performance, and is also important for health due to its contribution to resting metabolic rate and as a site for glucose uptake and storage. Numerous endogenous and exogenous factors influence muscle mass. Much of what is currently known regarding muscle protein turnover is owed to the development and use of stable isotope tracers.
View Article and Find Full Text PDFMagnetic resonance imaging (MRI) is the current gold standard for measuring changes in muscle size (cross-sectional area [CSA] and volume) but can be cost-prohibitive and resource-intensive. We evaluated the validity of B-mode ultrasonography (US) as a low-cost alternative to MRI for measuring muscle hypertrophy and atrophy in response to resistance training and immobilization, respectively. Fourteen young men performed 10wk of unilateral resistance training (RT) to induce muscle hypertrophy.
View Article and Find Full Text PDFObjective: Sleep loss has emerged as a risk factor for the development of impaired glucose tolerance. The mechanisms underpinning this observation are unknown; however, both mitochondrial dysfunction and circadian misalignment have been proposed. Because exercise improves glucose tolerance and mitochondrial function, and alters circadian rhythms, we investigated whether exercise may counteract the effects induced by inadequate sleep.
View Article and Find Full Text PDFLoading of skeletal muscle changes the tissue phenotype reflecting altered metabolic and functional demands. In humans, heterogeneous adaptation to loading complicates the identification of the underpinning molecular regulators. A within-person differential loading and analysis strategy reduces heterogeneity for changes in muscle mass by ∼40% and uses a genome-wide transcriptome method that models each mRNA from coding exons and 3' and 5' untranslated regions (UTRs).
View Article and Find Full Text PDFSkeletal muscle plays a pivotal role in the maintenance of physical and metabolic health and, critically, mobility. Accordingly, strategies focused on increasing the quality and quantity of skeletal muscle are relevant, and resistance exercise is foundational to the process of functional hypertrophy. Much of our current understanding of skeletal muscle hypertrophy can be attributed to the development and utilization of stable isotopically labeled tracers.
View Article and Find Full Text PDFKey Points: Sleep restriction has previously been associated with the loss of muscle mass in both human and animal models. The rate of myofibrillar protein synthesis (MyoPS) is a key variable in regulating skeletal muscle mass and can be increased by performing high-intensity interval exercise (HIIE), although the effect of sleep restriction on MyoPS is unknown. In the present study, we demonstrate that participants undergoing a sleep restriction protocol (five nights, with 4 h in bed each night) had lower rates of skeletal muscle MyoPS; however, rates of MyoPS were maintained at control levels by performing HIIE during this period.
View Article and Find Full Text PDFEndocrinol Diabetes Metab
October 2019
Background: The effect of substantive doses of essential amino acids (EAA) on incretin and insulin production, and the impact of age upon this effect, is ill-defined.
Methods: A 15-g oral EAA drink was administered to young (N = 8; 26 ± 4.4 years) and older (N = 8; 69 ± 3.
Sarcopenia is the age-related loss of skeletal muscle mass, strength and function, which may be accelerated during periods of physical inactivity. Declines in skeletal muscle and functionality not only impacts mobility but also increases chronic disease risk, such as type 2 diabetes. The aim of this study was to measure adaptive metabolic responses to acute changes in habitual activity in a cohort of overweight, pre-diabetic older adults (age = 69 ± 4 years; BMI = 27 ± 4 kg/m, = 17) when using non-targeted metabolite profiling by multisegment injection-capillary electrophoresis-mass spectrometry.
View Article and Find Full Text PDFAge is a primary risk factor for a number of chronic diseases including mobility disability, cardiovascular disease (CVD), type 2 diabetes (T2D), and cancer. Most physical activity guidelines emphasize the performance of 150 min of moderate-to-vigorous or 75 min of vigorous aerobic exercise training (AET) weekly for reduction of chronic disease risk. Nonetheless, there is an emerging body of evidence showing that resistance exercise training (RET) appears to be as effective as AET in reducing risk of several chronic diseases.
View Article and Find Full Text PDFThe maintenance of skeletal muscle mass and strength throughout life is a key determinant of human health and well-being. There is a gradual loss of both skeletal muscle mass and strength with ageing (a process termed sarcopenia) that increases the risk of functional dependence, morbidity and mortality. Understanding the factors that regulate the size of human muscle mass, particularly during the later years of life, has therefore become an area of intense scientific inquiry.
View Article and Find Full Text PDFSkeletal muscle supports locomotion and serves as the largest site of postprandial glucose disposal; thus it is a critical organ for physical and metabolic health. Skeletal muscle mass is regulated by the processes of muscle protein synthesis (MPS) and muscle protein breakdown (MPB), both of which are sensitive to external loading and aminoacidemia. Hyperaminoacidemia results in a robust but transient increase in rates of MPS and a mild suppression of MPB.
View Article and Find Full Text PDFBackground: Physical inactivity impairs insulin sensitivity, which is exacerbated with aging. We examined the impact of 2 wk of acute inactivity and recovery on glycemic control, and integrated rates of muscle protein synthesis in older men and women.
Methods: Twenty-two overweight, prediabetic older adults (12 men, 10 women, 69 ± 4 y) undertook 7 d of habitual activity (baseline; BL), step reduction (SR; <1,000 steps.