Antiaging agents: pharmacological therapy targeted at preserving skeletal muscle size and function in aging adults.

Purpose Of Review: Aging population rates are significantly increasing and improved quality of life during aging is a top priority. The decline in skeletal muscle mass and strength is a major concern with aging, as it impairs the ability to perform activities of daily living and significantly diminishes quality of life. Effective strategies to counteract this decline are necessary for supporting longevity and enhancing quality of life in older adults.

Understanding Dietary Protein Quality: Digestible Indispensible Amino Acid Scores and Beyond.

Dietary protein quality refers to the capacity of a food to meet the human metabolic needs for essential amino acids (EAAs) and nitrogen. This is critical in low- and middle-income countries, where severe protein malnutrition occurs, and relevant in higher-income countries, where increasing dietary EAA intake may improve health and function. There are several methods to assess protein quality, each with different objectives.

Effects of exercise with or without a hypocaloric diet on intermuscular and intramuscular fat: a systematic review.

Background: Intermuscular (InterMAT) and intramuscular (IntraMAT) adipose tissues are key contributors to skeletal muscle function and metabolic health.

Objective: In this systematic review, we aimed to investigate the impact of different types of exercise with or without a hypocaloric diet on reducing InterMAT and IntraMAT in various muscle tissues.

Method: A literature search was performed via PubMed, Cochrane Library, Scopus, and Web of Science from inception until February 2025.

The effect of nandrolone decanoate administration on fatigue during a volume-overload stress in male mice.

The effect of nandrolone decanoate on fatigue was examined during a volume-overload training stress in 3-month-old male C57Bl/6J mice (n = 24). Mice were randomized into two exercising groups and a control group (C). The exercising animals performed a 3-day per week resistance training program for 3 weeks.

The Effect of Nicotinamide Mononucleotide and Riboside on Skeletal Muscle Mass and Function: A Systematic Review and Meta-Analysis.

Introduction: Sarcopenia is associated with the loss of skeletal muscle function and mass. Nicotinamide precursors, such as nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR), have received attention for their potential to improve NAD levels and mitigate age-related sarcopenia in preliminary models, though evidence on their effects in older adults remains inconclusive.

Methods: We searched PubMed, Cochrane Library, Web of Science, and Scopus to identify randomized controlled trials (RCTs), comparing NR or NMN vs.

Crossover Trial of Exogenous Ketones on Cardiometabolic Endpoints in Heart Failure With Preserved Ejection Fraction.

Background: The etiology of exercise intolerance in heart failure with preserved ejection fraction (HFpEF) is multifactorial. Several contributing pathways may be improved by ketone ester (KE).

Objectives: This study aims to determine whether KE improves exercise tolerance in HFpEF.

Effect of 3 Different Daily Protein Intakes in a 2-Meal Eating Pattern on Protein Turnover in Middle Age and Older Adults: A Randomized Controlled Trial.

Background: Reduced meal frequency patterns have become popular for weight loss, maintenance, and improving cardiometabolic health. The extended fasting windows with these dietary patterns could lead to greater protein breakdown, which is a concern for middle-aged and older adults who may need higher protein intakes to maintain or increase net protein balance.

Objectives: This study aimed to quantify muscle and whole-body protein kinetic responses to 3 different daily protein intakes within a 2-meal eating pattern.

Consideration of the role of protein quality in determining dietary protein recommendations.

The quality of a dietary protein refers to its ability to provide the EAAs necessary to meet dietary requirements. There are 9 dietary amino acids that cannot be metabolically produced in the body and therefore must be consumed as part of the diet to avoid adverse metabolic consequences. These (EAAs) serve a variety of roles in the body.

The anabolic response to a ground beef patty and soy-based meat alternative: a randomized controlled trial.

Background: Soy-based meat alternatives (SBMA) are becoming increasingly popular, but it is unclear if they have the same anabolic effect on skeletal muscle as animal meat.

Objectives: We aimed to compare the stimulation of skeletal muscle protein synthesis by consumption of 1 or two 4 oz patties of SBMA with 4 oz (80% protein/20% fat) beef.

Methods: The study design was a randomized controlled trial.

Consuming Whey Protein with Added Essential Amino Acids, Not Carbohydrate, Maintains Postexercise Anabolism While Underfed.

Purpose: Energy deficiency decreases muscle protein synthesis (MPS), possibly due to greater whole-body essential amino acid (EAA) requirements and reliance on energy stores. Whether energy deficit-induced anabolic resistance is overcome with non-nitrogenous supplemental energy or if increased energy as EAA is needed is unclear. We tested the effects of energy as EAA or carbohydrate, combined with an EAA-enriched whey protein, on postexercise MPS (%·h -1 ) and whole-body protein turnover (g protein·240 min -1 ).

Stimulation of muscle protein synthesis with low-dose amino acid composition in older individuals.

Essential amino acid (EAA)-based compositions have been shown to be effective stimulators of muscle protein synthesis, but the lower limit of effective dosage is not clear. We have used stable isotope tracer methodology to quantify the response of muscle protein fractional synthetic rate (FSR) to a dose of 3.6 g of a high-leucine composition of EAAs plus arginine in older subjects.

Early Life Androgen Administration Attenuates Aging Related Declines in Muscle Protein Synthesis.

Purpose: This study examined the acute and long-term effects of nandrolone decanoate (ND) on fractional synthetic rates (FSR).

Methods: Male C57BL/6 mice were randomized into ND ( n = 20) or sham ( n = 20) groups. ND injections (10 g·kg -1 ·wk -1 ) started at 7 months of ages and continued for 6 wk.

Dietary protein recommendations to support healthy muscle ageing in the 21st century and beyond: considerations and future directions.

This review explores the evolution of dietary protein intake requirements and recommendations, with a focus on skeletal muscle remodelling to support healthy ageing based on presentations at the 2023 Nutrition Society summer conference. In this review, we describe the role of dietary protein for metabolic health and ageing muscle, explain the origins of protein and amino acid (AA) requirements and discuss current recommendations for dietary protein intake, which currently sits at about 0⋅8 g/kg/d. We also critique existing (e.

International Society of Sports Nutrition Position Stand: Effects of essential amino acid supplementation on exercise and performance.

Position Statement: The International Society of Sports Nutrition (ISSN) presents this position based on a critical examination of literature surrounding the effects of essential amino acid (EAA) supplementation on skeletal muscle maintenance and performance. This position stand is intended to provide a scientific foundation to athletes, dietitians, trainers, and other practitioners as to the benefits of supplemental EAA in both healthy and resistant (aging/clinical) populations. EAAs are crucial components of protein intake in humans, as the body cannot synthesize them.

Guidelines for parenteral nutrition in preterm infants: The American Society for Parenteral and Enteral Nutrition.

Background: Parenteral nutrition (PN) is prescribed for preterm infants until nutrition needs are met via the enteral route, but unanswered questions remain regarding PN best practices in this population.

Methods: An interdisciplinary committee was assembled to answer 12 questions concerning the provision of PN to preterm infants. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) process was used.

Foundational Nutrition: Implications for Human Health.

Human nutrition, and what can be considered "ideal" nutrition, is a complex, multi-faceted topic which many researchers and practitioners deliberate. While some attest that basic human nutrition is relatively understood, it is undeniable that a global nutritional problem persists. Many countries struggle with malnutrition or caloric deficits, while others encounter difficulties with caloric overconsumption and micronutrient deficiencies.

Associations of Bioavailable Serum Testosterone With Cognitive Function in Older Men: Results From the National Health and Nutrition Examination Survey.

Background: Age-associated cognitive decline may be influenced by testosterone status. However, studies evaluating the impact of bioavailable testosterone, the active, free testosterone, on cognitive function are scarce. Our study determined the relationship between calculated bioavailable testosterone and cognitive performance in older men.

Testosterone undecanoate administration prevents declines in fat-free mass but not physical performance during simulated multi-stressor military operations.

Male military personnel conducting strenuous operations experience reduced testosterone concentrations, muscle mass, and physical performance. Pharmacological restoration of normal testosterone concentrations may attenuate performance decrements by mitigating muscle mass loss. Previously, administering testosterone enanthate (200 mg/wk) during 28 days of energy deficit prompted supraphysiological testosterone concentrations and lean mass gain without preventing isokinetic/isometric deterioration.

Continuous oral stable isotope ingestion to measure whole-body protein turnover.

Background & Aims: Protein kinetic responses to nutrition and exercise interventions are commonly evaluated using a primed-constant infusion of stable isotope tracers. While this methodology is state-of-the-art, the required preparation at a certified pharmacy makes the utilization of isotope infusion both expensive and logistically cumbersome. Oral tracer ingestion has been used to quantify 24-h whole-body protein status; however, this does not permit examination of acute interventional effects.

The contributory role of vascular health in age-related anabolic resistance.

Sarcopenia, or the age-related loss of skeletal muscle mass and function, is an increasingly prevalent condition that contributes to reduced quality of life, morbidity, and mortality in older adults. Older adults display blunted anabolic responses to otherwise anabolic stimuli-a phenomenon that has been termed anabolic resistance (AR)-which is likely a casual factor in sarcopenia development. AR is multifaceted, but historically much of the mechanistic focus has been on signalling impairments, and less focus has been placed on the role of the vasculature in postprandial protein kinetics.

Proteasome- and Calpain-Mediated Proteolysis, but Not Autophagy, Is Required for Leucine-Induced Protein Synthesis in C2C12 Myotubes.

Muscle protein synthesis and proteolysis are tightly coupled processes. Given that muscle growth is promoted by increases in net protein balance, it stands to reason that bolstering protein synthesis through amino acids while reducing or inhibiting proteolysis could be a synergistic strategy in enhancing anabolism. However, there is contradictory evidence suggesting that the proper functioning of proteolytic systems in muscle is required for homeostasis.

Perioperative amino acid infusion reestablishes muscle net balance during total hip arthroplasty.

Surgery and anesthesia induce a catabolic response that leads to skeletal muscle protein loss. Previous investigations have observed positive effects of perioperative nutrition. Furthermore, the benefits of exogenous amino acids on muscle protein kinetics are well established.

Effects of testosterone undecanoate on performance during multi-stressor military operations: A trial protocol for the Optimizing Performance for Soldiers II study.

Background: Previously, young males administered 200 mg/week of testosterone enanthate during 28 days of energy deficit (EDef) gained lean mass and lost less total mass than controls (Optimizing Performance for Soldiers I study, OPS I). Despite that benefit, physical performance deteriorated similarly in both groups. However, some experimental limitations may have precluded detection of performance benefits, as performance measures employed lacked military relevance, and the EDef employed did not elicit the magnitude of stress typically experienced by Soldiers conducting operations.