Although the benefits of physical activity are established across all age groups, researchers have recently noted that there is uncertainty as to which correlates and determinants of physical activity contribute to well-informed interventions and policies, particularly for the time frame of early childhood. The following narrative review highlights salient factors related to physical activity during early childhood, particularly in the United States, with respect to a socioecological framework. Discussion of factors at the individual (demographic, genetic), interpersonal (family support and perceptions of competence), organizational (e.g., preschool attended, preschool quality, teacher characteristics), community (availability, use, and perceptions of play spaces), and policy levels is included. While researchers often work within a public health framework that focuses on moderate-to-vigorous physical activity, or total (light-to-vigorous) physical activity, this may not fully align with how young children move. The importance of structured and unstructured play, risky play, and nature-based play are highlighted. Implications for basic and applied scientists, clinicians, and practitioners are addressed. Suggestions for future work include consideration of the context of physical activity, associations with other health behaviors, and further examination of the interpersonal and community level factors.

Human exercise performance is influenced by factors related to inherent individual characteristics along with other modifiable factors. During exercise in the heat, sweating provides the major avenue for cooling. When body water losses exceed 2% body mass, changes in physiological responses are observed in a dose-response manner. Human sweat varies in electrolyte content due to differences in ion channel re-absorption in the sweat duct. Moderate hypohydration (> 2% body mass) is associated with physical and mental performance impairments, although this depends on the environment (e.g., warm to hot) and type of exercise (e.g., endurance) or cognitive task (e.g., sustained attention, executive function, motor coordination) involved. This begs the question: Is simply adding water the optimal “solution” to improving human performance during events eliciting dehydration? This review focuses on literature applicable to athletes and military personnel during exertion in the heat. Historically, optimally formulating a sports drink to ingest during exercise has focused on appropriate levels of carbohydrate, with more recent interest spanning from higher electrolyte concentrations to amino acid formulations. Evidence to support recommendations regarding beverage bioavailability during exercise comes from studies comparing the appearance of heavy water (tagged within a beverage) in blood. Fluid delivery appears enhanced with moderately concentrated carbohydrate while electrolyte composition plays a lesser role. Despite the robust historical scientific literature related to fluid replacement, the quest for the optimal sports drink during exercise in the heat continues to generate interest considering global warming trends and the increasing numbers of new hydration-related products for exercising individuals.

The observation that physical activity (PA) reduces the risk of coronary heart disease dates back more than 70 years ago and it is now established that regular PA reduces all-cause mortality, in part, by reducing the risk of numerous chronic diseases including coronary heart disease, stroke, cancer, type 2 diabetes, and Alzheimer's disease. During the past decade the increased use of activity tracking devices has significantly improved our understanding of the dose-response relationships between PA and all-cause mortality. Further, our appreciation of the impact that prolonged sitting has on all-cause mortality has increased. Moreover, new research provides key insight into the signaling mechanisms that connect PA to the reduced risk of disease in multiple organ systems. Therefore, given the recent advances in the study of PA and all-cause mortality, it is an appropriate time to review the latest evidence on this topic as well as the mechanisms responsible for the PA-induced protection against all-cause mortality. Therefore, this review will summarize recent data on the dose-response association between PA on all-cause mortality and the negative impact that sedentary behavior has on all-cause mortality. Further, we also highlight potential mechanisms linking PA with the reduced risk of developing several chronic diseases. Finally, we conclude with a brief discussion of the emerging evidence that the health benefits associated with PA are derived, in part, from skeletal muscle-organ crosstalk involving muscle produced hormones (myokines) that exert their effects in either an autocrine, paracrine, or endocrine manner.

Substantial reductions in muscle motor unit numbers accompany ageing and occur in parallel the age-related changes in skeletal muscle mass and fibre number. These motor unit changes are reflected in reduced motor neuron numbers and size, axonal integrity and disrupted pre-and post-synaptic neuromuscular junctions (NMJ). Conversely, data indicate that the effects of ageing on neuromuscular transmission are relatively minor. Some authors have therefore argued that structural degeneration of motor axons and NMJ are unimportant in the pathogenesis of sarcopenia and for a non-neurogenic origin for ageing-induced muscle loss. Increased Reactive Oxygen Species (ROS) activities and changes in redox status are a feature of ageing and may play a key role in muscle loss through increased mitochondrial peroxide generation. This article will review the changes in motor units and NMJ seen during ageing and develop the argument that the changes in muscle mitochondrial peroxide generation and redox status may be caused by age-related changes in neuromuscular structure, but are not directly related to neuromuscular transmission. This provides an alternative explanation on how age-related changes in neural tissue might drive skeletal muscle fibre loss and weakness. Exercise interventions are known to reduce muscle loss and weakness in the elderly, but studies of such interventions on age-related changes in motor units, motor neurons or NMJ structure and function provide conflicting data. A further aim is therefore to identify areas where there is a need for novel research to understand whether, and how, targeted or long-term exercise might influence neuromuscular changes in ageing.

Throughout history, cultural norms and stereotypes have discouraged resistance training in women. Today, as awareness and acceptance of resistance training in women has grown, supported by scientific research and advocacy, more women are achieving health and performance benefits from resistance training. This narrative review discusses the current scientific literature on sexual dimorphisms, the mechanisms underlying health and performance adaptations of resistance training in women, with implications for program design. In general, the physiological adaptations to resistance training in women are mediated largely by the neuroendocrine and immune systems, similar to in men albeit via some distinct predominant pathways involving sex hormones estrogen, testosterone, growth hormone (GH), and insulin-like growth factor- I (IGF-I). As a result, women may have unique adaptations in terms of muscle hypertrophy, substrate utilization, fatiguability, and recovery. Despite subtle physiological differences, women achieve measurable increases in strength, power and athletic performance via engaging in resistance training programs of sufficient frequency, intensity, and duration. Moreover, beyond performance, resistance training has a favorable impact on women’s health including metabolic health, body composition, bone health, cardiovascular health, mental health, self-esteem, and body image. Resistance training recommendations for men and women are highly similar and goal-dependent, with some specific caveats that need to be addressed in women. As resistance training has become regarded as a key element of programs for achieving performance and health improvements in women, additional research may further our understanding.

Background: Acute myocardial infarction (AMI) remains the leading form of cardiovascular morbidity and mor- tality, while exercise is a preventative and therapeutic countermeasure. The collective benefits of exercise on the heart are called cardioprotection. Exercise-induced cardioprotection encompasses four broad areas: 1) cardio- vascular disease (CVD) risk factor improvement, 2) anatomical remodeling of the heart, 3) improved cardiac physiologic function, and 4) mechanisms of exercise preconditioning.

Discussion: With respect to the latter area of cardioprotection, research indicates that a few days of moderate intensity aerobic exercise preconditions the heart against cardiac dysrhythmias, ventricular pump dysfunction, and tissue death. The short duration protective timeframe, hours to days after exercise, indicates that the mechanisms are biochemical in nature. Protective mechanisms within exercised hearts include endogenous antioxidant enzymes, better regulation of cytosolic Ca²⁺, and more efficient bioenergetics. However, a formative body of work conducted over the last decade indicates that additional exogenous mechanisms may be receptor mediated, presumably providing cardioprotection via circulating factors. Preliminary findings indicate that tissue- to-tissue cross talk involves cardioprotective paracrine factors derived from muscle or autocrine factors origi- nating from the heart itself. This protection is termed exogenous (or remote) cardiac preconditioning, and appears to include δ-opioid receptors, IL-6 receptors, and perhaps other surface receptors on exercised cardiac tissue.

Conclusion: The current review outlines existing knowledge on exercise and factors of cardiac preconditioning, and highlights the avenues for next-step scientific advances to understanding treatments against AMI.

Heart failure (HF) poses a serious threat to public health in an aging population. HF with reduced ejection fraction (HFrEF) historically was the focus for developing prevention and management strategies, including exercise training in HFrEF patients. However, HF with preserved ejection fraction (HFpEF) is increasingly common among older adults. There are no well-established treatment options making its primary prevention critical. This article reviews the role of exercise in the prevention and management of HF. Selected published articles informed discussion of HF etiology, evidence for the role of exercise in HF, and the biologic mechanisms linking exercise with HF development and prognosis. HF is a complex syndromic condition that manifests with severe exercise intolerance. Several causes of HF-related exercise intolerance respond to exercise training and two randomized controlled exercise interventions in HFrEF patients have demonstrated safety and efficacy for improved physical work capacity, quality of life, and mortality endpoints in medically stable HF patients. At present, only epidemiological cohort data are available for HFpEF outcomes, but the data are generally consistent in supporting lower risk of HFpEF development with levels of lifestyle physical activity meeting recommended amounts. Clinical trial evidence is needed to support this observation in HFpEF. Exercise training is established as part of guideline directed treatment of HFrEF patients. Lifestyle physical activity at guideline recommended amounts appears to be associated with lower risk of developing both HFrEF and HFpEF. There has yet to be a definitive clinical trial on exercise training and HFpEF treatment.

Background: Cancer induced cachexia, the involuntary loss of lean body mass and adipose tissue, is a debilitating syndrome experienced in up to 80% of all cancer patients. Cachexia is associated with poor treatment outcomes including decreased quality of life, increased risk of infection, disease progression, and mortality. Recent research suggests that exercise interventions may improve cachexia; however, there is a need for comprehensive and systematic review of the literature to evaluate the role of specific interventions on cancer-induced cachexia.

Methods: We conducted a systematic review examining the efficacy of physical activity interventions, particularly resistance training, on cancer-induced cachexia outcomes. We searched seven electronic databases (PubMed, Embase, EBSCO, SCOPUS, Web of Science, PsychINFO, Cochrane) for articles published up to September 2023, yielding 7 eligible studies.

Results: Sample sizes ranged from 20 to 190 participants per study. Studies included pancreatic (n = 3), head & neck (n = 3), and Gastrointestinal (n = 1) cancers. Mean age ranged from 51.90 to 67.1 years old and females comprised 51% of the participants. Most studies implemented resistance training interventions (73%), ranging from 3 months to 6 months in duration. Although the patterns of outcomes indicate promising results, the effect sizes for all models were small and not statistically significant.

Conclusions: The science of exercise interventions to improve outcomes in those with cancer-related cachexia is still emerging although progressive resistance training appears to be the most promising countermeasure. Authors encourage the development of high-quality, fully powered randomized controlled trials (RCTs) examining physical exercise interventions aimed at mitigating cancer-induced cachexia.

Purpose: The purpose of this narrative review is to: 1) summarize findings from the three Studies of a Targeted Risk Reduction Intervention through Defined Exercise (STRRIDE) randomized trials regarding the differential effects of exercise amount, intensity, and mode on metabolic syndrome (MetS); and 2) compare the STRRIDE findings with other published randomized exercise trials related to changes in MetS.

Methods: A literature review was performed to investigate the effects of exercise on composite measures of MetS. PubMed was searched between October 2023 and December 2023. To be included in this review, studies must have employed a randomized study design, whereby exercise amount, intensity, or mode was varied.

Results: Findings from the STRRIDE trials and other randomized exercise trials suggest: 1) there is a relationship between exercise energy expenditure (ExEE) and improvements in composite measures of MetS; 2) there may be an asymptotic effect for ExEE beyond which further improvements in MetS are negligible or counterproductive; 3) improvements in composite measures of MetS are closely linked to insulin sensitivity; and 4) without controlling for total ExEE, combined aerobic and resistance training interventions offer the most robust improvements forcomposite MetS outcomes compared to either mode alone.

Conclusion: Additional, large-scale, randomized exercise trials should be designed to investigate the potentialasymptotic effect and associated threshold for ExEE, the interaction between exercise intensity and baseline insulinsensitivity, and the independent effects of exercise mode on MetS.