Short term e-bicycle riding results in favorable cardiometabolic shifts in moderately active adults.

Purpose: Electric bikes (EB) are a form of active transportation with demonstrated health benefits. The purpose of this study was to determine the influence of riding an EB for one week on indices of cardiometabolic health in middle-aged adults.

Methods: Adults (n = 22; age = 57.

A comparison of energy expenditure and perceived exertion between standard axillary crutches, knee scooters, and a hands-free crutch.

Background: Ambulation using standard axillary crutches (SACs) is associated with increased energy expenditure (EE) and decreased ability to perform activities of daily living (ADLs). Using a hands-free crutch (HFC) displays potential for easier completion of ADLs and reduction in energy requirements.

Objectives: To determine if a HFC elicits lower EE and heart rate (HR), improvement in performance of ADLs, and decreased rating of perceived exertion (RPE) compared to common ambulatory devices.

Intuitive Eating and Biomarkers Related to Cardiovascular Disease in Older Adults.

Objective: Examine whether exercise and diet motivation are associated with 4 biomarkers related to cardiovascular disease.

Design: Cross-sectional analysis. Data collection involved questionnaires, blood draws, body composition assessments, and accelerometry.

Perceptions of Weight Loss in Older Adults Following a 6-Month Weight Loss Program: A Qualitative Research Study.

Background: Obesity in older adults contributes to increasing comorbidities and decreased quality of life. There is limited research that includes older adults' perspectives on weight loss.

Objective: The purpose of this qualitative study was to gain a better understanding of older adults' perceptions and experiences related to weight loss immediately after a 6-month weight loss intervention.

Influence of time of day and intermittent aerobic exercise on vascular endothelial function and plasma endothelin-1 in healthy adults.

Reduced flow-mediated dilation (FMD) and elevated plasma endothelin-1 (ET-1) levels may contribute to the higher incidence of adverse cardiovascular events observed in the morning hours. A single bout of intermittent exercise abolishes the diurnal variation in FMD. Studies examining the effects of exercise on vascular and plasma ET-1 responses at different times of day are lacking.

Associations Among Physical Activity Level and Skeletal Muscle Antioxidants in Older Adults.

Background: Endogenous antioxidants are critical to limiting cellular oxidative damage.

Methods: The authors determined if habitual physical activity (PA) and cardiorespiratory fitness were associated with skeletal muscle expression of endogenous antioxidants (superoxide dismutase, catalase, and glutathione peroxidase) and circulating oxidative stress markers (serum 8-hydroxy-2'-deoxyguanosine [8-OHdG]; oxidized low-density lipoprotein [LDL]) in older adults. Moderate to vigorous PA (MVPA) was estimated using a validated PA questionnaire in 26 older adults (mean [SD]; M/F = 9/17, age = 68 [4] y, body mass index = 26 [3] kg·m-2).

Aerobic or resistance exercise performed the previous day does not attenuate postprandial hyperglycemia-induced endothelial dysfunction in overweight/obese adults.

Introduction: Postprandial hyperglycemia (PPH) impairs vascular endothelial function (VEF). A single bout of aerobic exercise (AE) attenuates PPH-induced decreases in brachial artery flow-mediated dilation (FMD), a non-invasive measure of VEF, in healthy adults for up to 17 h post-exercise. Studies examining the effects of resistance exercise (RE) on postprandial FMD responses are lacking.

Altering Physical Activity Influences Insulin Responses to Glucose Ingestion in Healthy Adults.

This study determined if varying physical activity (PA) the day prior to an oral glucose tolerance test (OGTT) differentially influenced postprandial glucose and insulin kinetics. Fifteen healthy, young adults participated in three OGTT trials the morning after performing 50% (LOW), 100% (HABITUAL), or 150% (HIGH) of their habitual PA (determined by 7-day pedometry). Trials were randomized and separated by at least 1-wk.

Effect of Aerobic Exercise Training and Essential Amino Acid Supplementation for 24 Weeks on Physical Function, Body Composition, and Muscle Metabolism in Healthy, Independent Older Adults: A Randomized Clinical Trial.

Background: Essential amino acids (EAA) and aerobic exercise (AE) acutely and independently stimulate skeletal muscle protein anabolism in older adults.

Objective: In this Phase 1, double-blind, placebo-controlled, randomized clinical trial, we determined if chronic EAA supplementation, AE training, or a combination of the two interventions could improve muscle mass and function by stimulating muscle protein synthesis.

Methods: We phone-screened 971, enrolled 109, and randomized 50 independent, low-active, nonfrail, and nondiabetic older adults (age 72 ± 1 years).

Effects of prior aerobic exercise on sitting-induced vascular dysfunction in healthy men.

Introduction: Acute aerobic exercise prevents sitting-induced impairment of flow-mediated dilation (FMD). Further, evidence suggests that sitting-induced impairment of FMD occurs via an oxidative stress-dependent mechanism that disrupts endothelial function.

Purpose: We hypothesized that acute aerobic exercise would prevent impairment of femoral artery FMD by limiting oxidative stress responses that increase endothelin-1 (ET-1) levels and disrupt nitric oxide (NO) status.

Skeletal muscle TLR4 and TACE are associated with body fat percentage in older adults.

Elevated skeletal muscle expression of toll-like receptor 4 (TLR4) has been linked to increased inflammation in clinical populations. TNFα converting enzyme (TACE), which cleaves membrane-bound TNFα (mTNFα) to its soluble (sTNFα) and more bioactive form, has been linked to chronic disease. In contrast, higher physical activity level is associated with decreased chronic disease risk and inflammation.

Effect of age on basal muscle protein synthesis and mTORC1 signaling in a large cohort of young and older men and women.

The rate of muscle loss with aging is higher in men than women. However, women have smaller muscles throughout the adult life. Protein content is a major determinant of skeletal muscle size.

Blunted IL-6 and IL-10 response to maximal aerobic exercise in patients with traumatic brain injury.

Introduction: In healthy individuals, strenuous exercise typically results in a transient increase in the inflammatory cytokine, interleukin-6 (IL-6). This increase in IL-6 is reported to have pleiotropic effects including increased glucose uptake, increased fat oxidation, and anti-inflammatory actions.

Purpose: The purpose of this study was to determine if patients with a traumatic brain injury (TBI) have a differential cytokine response to exercise compared to healthy control subjects (CON).

Exercise training modifies ghrelin and adiponectin concentrations and is related to inflammation in older adults.

The purpose of this study was to observe exercise training-induced effects on adiponectin, leptin, and ghrelin. Twenty-nine older, healthy participants were classified as physically active (comparison group: N = 15, 70.9 ± 1.

Short-term bed rest increases TLR4 and IL-6 expression in skeletal muscle of older adults.

Bed rest induces significant loss of leg lean mass in older adults. Systemic and tissue inflammation also accelerates skeletal muscle loss, but it is unknown whether inflammation is associated to inactivity-induced muscle atrophy in healthy older adults. We determined if short-term bed rest increases toll-like receptor 4 (TLR4) signaling and pro-inflammatory markers in older adult skeletal muscle biopsy samples.

Addition of carbohydrate or alanine to an essential amino acid mixture does not enhance human skeletal muscle protein anabolism.

In humans, essential amino acids (EAAs) stimulate muscle protein synthesis (MPS) with no effect on muscle protein breakdown (MPB). Insulin can stimulate MPS, and carbohydrates (CHOs) and insulin decrease MPB. Net protein balance (NB; indicator of overall anabolism) is greatest when MPS is maximized and MPB is minimized.

Protein blend ingestion following resistance exercise promotes human muscle protein synthesis.

High-quality proteins such as soy, whey, and casein are all capable of promoting muscle protein synthesis postexercise by activating the mammalian target of rapamycin (mTORC1) signaling pathway. We hypothesized that a protein blend of soy and dairy proteins would capitalize on the unique properties of each individual protein and allow for optimal delivery of amino acids to prolong the fractional synthetic rate (FSR) following resistance exercise (RE). In this double-blind, randomized, clinical trial, 19 young adults were studied before and after ingestion of ∼19 g of protein blend (PB) or ∼18 g whey protein (WP) consumed 1 h after high-intensity leg RE.

Skeletal muscle autophagy and protein breakdown following resistance exercise are similar in younger and older adults.

Background: The loss of skeletal muscle mass and strength during aging, sarcopenia, increases the risk for falls and dependency. Resistance exercise (RE) training is effective at improving muscle mass and strength in older adults; however, aging is associated with reduced training-induced hypertrophy. Recent research has illustrated an impaired muscle protein synthetic response following an acute bout of RE in older adults but much less is known regarding the effect of acute RE on muscle protein breakdown (MPB).

Rapamycin does not affect post-absorptive protein metabolism in human skeletal muscle.

Unlabelled: Administration of the mTORC1 inhibitor, rapamycin, to humans blocks the increase in skeletal muscle protein synthesis in response to resistance exercise or amino acid ingestion.

Objective: To determine whether rapamycin administration influences basal post-absorptive protein synthesis or breakdown in human skeletal muscle.

Materials/methods: Six young (26±2 years) subjects were studied during two separate trials, in which each trial was divided into two consecutive 2 h basal periods.

PAX7+ satellite cells in young and older adults following resistance exercise.

Introduction: Resistance exercise (RE) stimulates a muscle protein anabolic response partially through enhanced satellite cell (SC) activity, however, age- and gender-related changes in SC content over a 24-h time course are not known.

Methods: Ten young (27 ± 2 years) men and women and 11 older (70 ± 2 years) men and women performed an acute bout of RE. Myofiber and SC characteristics were determined from muscle biopsies of the vastus lateralis using immunohistochemistry.

A moderate acute increase in physical activity enhances nutritive flow and the muscle protein anabolic response to mixed nutrient intake in older adults.

Background: Nutrient stimulation of muscle protein anabolism is blunted with aging and may contribute to the development and progression of sarcopenia in older adults. This is likely due to insulin resistance of protein metabolism and/or endothelial dysfunction with a reduction in nutritive flow, both of which can be improved by aerobic exercise.

Objective: Our objective was to determine whether increasing physical activity can enhance the muscle protein anabolic effect of essential amino acid (EAA) + sucrose intake in older subjects by improving nutritive flow and/or insulin signaling.

Reactive hyperemia is not responsible for stimulating muscle protein synthesis following blood flow restriction exercise.

Blood flow restriction (BFR) to contracting skeletal muscle during low-intensity resistance exercise training increases muscle strength and size in humans. However, the mechanism(s) underlying these effects are largely unknown. We have previously shown that mammalian target of rapamycin complex 1 (mTORC1) signaling and muscle protein synthesis (MPS) are stimulated following an acute bout of BFR exercise.

Bed rest impairs skeletal muscle amino acid transporter expression, mTORC1 signaling, and protein synthesis in response to essential amino acids in older adults.

Skeletal muscle atrophy during bed rest is attributed, at least in part, to slower basal muscle protein synthesis (MPS). Essential amino acids (EAA) stimulate mammalian target of rapamycin (mTORC1) signaling, amino acid transporter expression, and MPS and are necessary for muscle mass maintenance, but there are no data on the effect of inactivity on this anabolic mechanism. We hypothesized that bed rest decreases muscle mass in older adults by blunting the EAA stimulation of MPS through reduced mTORC1 signaling and amino acid transporter expression in older adults.

Aging impairs contraction-induced human skeletal muscle mTORC1 signaling and protein synthesis.

Background: Sarcopenia, the loss of skeletal muscle mass during aging, increases the risk for falls and dependency. Resistance exercise (RE) training is an effective treatment to improve muscle mass and strength in older adults, but aging is associated with a smaller amount of training-induced hypertrophy. This may be due in part to an inability to stimulate muscle-protein synthesis (MPS) after an acute bout of RE.