Scholarly Works, Human Nutrition, Foods, and Exercise

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CherryZZZ: A Protocol for a Randomized, Double-Blind, Placebo-Controlled, Cross-Over Pilot Study Testing Tart Cherry Juice in Older Adults with Self-Reported Insomnia
VanderMark, Esther; Baniassadi, Amir; Wolfe, Alex; Cladis, Dennis P.; Dufour, Alyssa B.; Millar, Courtney L. (MDPI, 2026-03-14)
Introduction: Two small, preliminary pilot studies report that 2 weeks of daily tart cherry juice consumption (half of the dose in the morning, half of the dose at night) may increase sleep quantity (assessed via a sleep diary or 1 night of polysomnography) in older adults with insomnia. A study of longer duration, with doses closer to bedtime, and daily objective monitoring of sleep via a wearable device may potentiate the observed impact of tart cherry juice intake on sleep. With the proposed changes to the study protocol, it is paramount to evaluate the study’s feasibility. Methods: The current study is a single-site, randomized, double-blind, cross-over pilot study in 20 older adults with self-reported insomnia. Eligible individuals will be randomly assigned to consume 16 oz. of tart cherry juice/day or placebo juice for 4 weeks each, separated by a 3-week washout period. Information on study feasibility, including recruitment rate, retention rate, safety, compliance, and study practicality, will be collected, as well as pre- and post-arm evaluations of sleep quantity/quality and biomarkers related to melatonin, cortisol, serotonin, and inflammation. Discussion: Identification of a dietary intervention that improves sleep quantity and quality may serve as a novel and feasible approach for older adults who suffer from insomnia. If successful, such a strategy would help mitigate the plethora of health consequences associated with poor sleep.
Estrogen, Epigenetics, and Cardiometabolic Health: Mechanisms and Therapeutic Strategies in Postmenopausal Women
Edwards, Ailene; Singh, Pranjal; Shah, Vyan; Chander, Vivek; Mishra, Sumita (MDPI, 2026-03-16)
The loss of estrogen following menopause is associated with a marked increase in cardiometabolic risk, accompanied by adverse changes in lipid metabolism, insulin sensitivity, vascular function, and systemic inflammatory tone. Emerging evidence suggests that estrogen signaling interacts with chromatin regulatory mechanisms, including DNA methylation, histone modifications, and chromatin remodeling, across multiple metabolic tissues. In this review, we examine current evidence linking estrogen receptor signaling to epigenetic modulation in cardiovascular, hepatic, adipose, vascular, and immune systems. We propose that epigenetic remodeling represents a plausible and testable mechanistic framework connecting estrogen depletion to cardiometabolic disease progression, while acknowledging that much of the mechanistic evidence derives from preclinical and in vitro systems and that direct longitudinal validation in human cardiovascular tissues remains limited. We further explore how this framework may contribute to understanding the “estrogen paradox” and the heterogeneous outcomes of hormone replacement therapy (HRT), particularly within the context of the timing hypothesis. Finally, we evaluate pharmacologic and lifestyle interventions, including structured exercise, dietary modulation, and cardiometabolic therapeutics, through the lens of potential epigenetic influence. Clarifying tissue-specific and immune-integrated chromatin responses to estrogen loss will be essential for advancing precision strategies aimed at improving cardiometabolic health in postmenopausal women.
Perceived reward certainty in the assessment of delay discounting
Downey, Haylee; Alvarez, Alicia; Ji, Wenyan; Lozano, Alicia; Hanlon, Alexandra L.; Stein, Jeffrey S. (Wiley, 2025-09-09)
Reward delays are often associated with reduced probability of reward, although standard assessments of delay discounting do not specify degree of reward certainty. Thus, the extent to which estimates of delay discounting are influenced by uncontrolled variance in perceived reward certainty remains unclear. Here we examine 370 participants who were randomly assigned to complete a delay discounting task when reward certainty was either unspecified (n=184) or specified as 100% (n = 186) in the task trials and task instructions. We examined potential group differences in (a) perceived reward certainty across a range of delays, (b) delay discounting, and (c) associations between perceived reward certainty and delay discounting. Delay significantly reduced perceived reward certainty in both groups, although delay did not significantly interact with group to affect perceived certainty. Despite higher perceived reward certainty in the specified group, no significant group difference in delay discounting was observed. Higher perceived reward certainty was associated with lower delay discounting in both groups. However, we found no evidence that specifying reward certainty influences estimates of delay discounting. Future research should examine whether perceived reward certainty moderates associations between delay discounting and health behavior and whether perceived reward certainty is impacted by interventions that change delay discounting.
The necessity for skeletal muscle contractile assays to assess treatment efficacy in DMD
Yuan, Claire; Sweeten, Amanda; Grange, Robert W. (OAE Publishing, 2025-03-05)
Body movement relies on skeletal muscles generating power to move limbs effectively. Power is defined as force multiplied by velocity: a muscle produces force at a specific velocity (the speed of muscle shortening) and this results in power. In diseases like Duchenne Muscular Dystrophy (DMD), the absence of dystrophin weakens muscles and impairs their shortening velocity, leading to decreased power and consequently, impaired movement. Additionally, the diaphragm and heart muscles are also affected in DMD, causing difficulty breathing and impaired cardiac function. Compromised cardiorespiratory function can ultimately lead to death. Given the complex etiology of DMD and the essential role of power in all affected muscles, it is crucial to assess potential treatments for their effectiveness in improving muscle function. This review focuses on fundamental physiological assays used to evaluate muscle function in skeletal and diaphragm muscles. Common assays include force-frequency, force-velocity, power, and eccentric protocols, which are conducted ex vivo, in situ, and in vivo in small rodents (such as mice and rats) and larger intermediate animal models such as the Golden Retriever Muscular Dystrophy dog. Existing data support the use of skeletal muscle contractile assays as objective tools for assessing the efficacy of treatments.
A novel ex vivo protocol that mimics length and excitation changes of human muscles during walking induces force losses in EDL but not in soleus of mdx mice
Hu, Xiao; McCrady, Allison N.; Bukovec, Katherine E.; Yuan, Claire; Miller, Emily Y.; Bour, Rachel K.; Bruce, Anthony C.; Crump, Katherine B.; Peirce, Shayne M.; Grange, Robert W.; Blemker, Silvia S. (Public Library of Science, 2025-04-07)
Although eccentric contraction protocols are widely used to study the pathophysiology and potential treatments for Duchenne muscular dystrophy (DMD), they do not reflect the stresses, strains, strain rates, and excitation profiles that DMD muscles experience during human daily functional tasks, like walking. This limitation of eccentric contractions may impede our understanding of disease progression in DMD and proper assessment of treatment efficacy. The goals of this study were to examine the extent of force loss induced by a gait cycling protocol we developed, and compare to that from a typical eccentric contraction protocol in soleus and extensor digitorum longus (EDL) muscles of mdx mice. To achieve this goal, mdx soleus and EDL muscles were subjected to eccentric contractions at three levels of strain (10%, 20% and 30% optimal length Lo) and up to 200 cycles of our gait cycling protocol that mimicked the length changes and excitation patterns of the corresponding muscles during human walking gait. Our results showed that EDL but not soleus muscles had significant losses in isometric tetanic forces after the cycling protocols. Compared to the eccentric contraction protocol, the decrements in contractile performance from the cycling protocol were similar to those from the eccentric contractions at 10% in soleus and 20% Lo in EDL. Together, these results indicated the gait cycling protocol is a valuable experimental approach to better understand disease progression and to screen and evaluate efficacy of novel therapeutics for DMD.
Sex differences in voluntary running behavior between C57BL/6 and BALB/cJ mouse strains do not correspond to changes in VO2 and RER
Amiri, Niloufar; Zhang, Haiyan; McMillan, Ryan P.; Grange, Robert W.; Drake, Joshua C. (Wiley, 2025-10-10)
Exercise adaptations are influenced by sex and genetic background, contributing to variability in metabolic and physiological responses. This study investigates sex and strain-specific differences following voluntary wheel running exercise training in submaximal and maximal oxygen consumption (VO2), respiratory exchange ratio (RER), and body composition in C57BL/6 and BALB/cJ mice. Male and female mice underwent 4 weeks of voluntary wheel running, followed by sub-maximal and maximal treadmill tests in a metabolic chamber. Results indicate differences in running volume across sexes and strains did not consistently predict changes in physiological adaptations. Female C57BL/6 mice, which ran three times more than males on average, exhibited higher submaximal VO2 compared to their male counterparts and to female BALB/cJ mice, despite no differences in RER. In contrast, male BALB/cJ mice, which ran nearly double the distance of their female counterparts, showed a modest decrease in average RER. During maximal treadmill tests, male BALB/cJ mice demonstrated enhanced endurance capacity, characterized by increased distance run and a trend towards lower RER and blood lactate levels at exhaustion, despite no significant changes in VO2 max. Regarding body composition, female C57BL/6 mice experienced a reduction in fat mass and an increase in lean mass, whereas no significant changes were observed in BALB/cJ mice of either sex. The study highlights the need to consider sex- and strain-specific factors when evaluating metabolic and endurance adaptations, and suggests VO2 testing in mice may not reflect adaptive response to voluntary wheel running.
Transcriptional Adaptations to Muscle Loading in a Murine Model of Achilles Tendinopathy
Easley, Dylan C.; Menarim, Bruno C.; Grange, Robert W.; Brolinson, P. Gunnar; Wang, Vincent M.; Dahlgren, Linda A. (Wiley, 2026-02-01)
Achilles tendinopathy limits mobility and decreases quality of life. Physical therapy (eccentric muscle loading) improves tendon function; however, the underlying mechanisms are unknown. This study investigated the effect of load magnitude and treatment duration in a mouse Achilles tendinopathy model. We hypothesized that loading would upregulate signaling and metabolic transcriptional networks associated with improved tendon healing. Mice were randomly assigned to muscle loading groups (50 or 100% body weight (BW)) or age-matched injured/untreated (IU) and naïve control groups. Following induction of Achilles tendinopathy via paired TGFB-β1 injections, loading was performed for 1, 2, or 4 weeks, mice euthanized, and Achilles tendons harvested for transcriptomics. The exercised groups exhibited relatively converging transcriptional patterns at 4 weeks, while the IU group was tightly associated with the naïve group over time, and diverging from both exercised groups at 2 and 4 weeks. Two weeks of exercise at either 50 or 100% BW load resulted in uniquely expressed gene networks not present in unexercised controls. Comparative assessment of the expression profile and functional annotation of networks across groups revealed that exercise differentially affected the innate immune response, sensory innervation and collagen biosynthesis during tendon repair. Ingenuity Pathway Analysis further suggests that 50% BW loading is associated with a shorter pro-inflammatory response and early matrix deposition in healing tendons compared to 100% BW loading. The transcriptional alterations seen in response to 50% BW eccentric muscle loading support the benefits of controlled loading exercises when treating Achilles tendinopathy.
Detecting and addressing eating disorders among individuals experiencing food insecurity: considerations for dietetic practice
Davis, Heather A.; Myers, Emily; Serrano, Elena L.; Misyak, Sarah A. (Frontiers, 2025-09-12)
In the United States, almost 10% of Americans will experience an eating disorder in their lifetime. Despite evidence that eating disorders occur across socio-economic backgrounds, the stereotypes of eating disorders being a disease of affluence persist. The experience of food insecurity, defined as limited or inconsistent physical and economic access to a sufficient amount and variety of nutritious food needed for a healthy life, is significantly associated with greater eating disorder symptoms. There are several reasons eating disorder symptoms may develop in people experiencing food insecurity, including food/benefit distribution cycles, shame, and weight bias. This Perspective highlights the relationship between food insecurity and eating disorders and provides informed recommendations specific to dietetic practice. Guidance is provided for Registered Dietitian Nutritionists (RDNs) in settings that serve individuals at risk of, or experiencing, food insecurity. RDNs should be informed on best practices for screening for eating disorders and providing appropriate referrals to eating disorder specific care, as well as encouraging realistic, achievable health behaviors, and using non-stigmatizing language.
Ampk alpha2 T172 activation dictates exercise performance and energy transduction in skeletal muscle
Montalvo, Ryan N.; Li, Xiaolu; Many, Gina M.; Sagendorf, Tyler J.; Yu, Qing; Shen, Wenqing; Wase, Nishikant; Burgardt, A. Robert; Zhang, Tong; Gritsenko, Marina A.; Gaffrey, Matthew J.; Bhonsle, Hemangi; Guan, Yuntian; Mao, Xuansong; Zhang, Mei; Qian, Wei-Jun; Yan, Zhen (American Association for the Advancement of Science, 2026-02-27)
Adenosine 5′-monophosphate–activated protein kinase (AMPK) is an energetic sensor for metabolic regulation and integration. Here, we used CRISPR-Cas9 to generate nonactivatable Ampkα knock-in (KI) mice with mutation of threonine-172 phosphorylation site to alanine (T172A), circumventing the limitations of previous genetic interventions that disrupt the protein stoichiometry. KI mice of Ampkα2, but not Ampkα1, demonstrated phenotypic changes with increased fat-to-lean mass, impaired endurance exercise capacity, and diminished mitochondrial maximal respiration and conductance in skeletal muscle. Integrated temporal multiomics analysis (proteomics/phosphoproteomics/metabolomics) in skeletal muscle at rest and during exercise establishes a pleiotropic yet imperative role of Ampkα2 T172 activation for glycolytic and oxidative metabolism, mitochondrial respiration, and contractile function. There is a substantial overlap of skeletal muscle proteomic changes in Ampkα2 T172A KI mice with that of patients with type 2 diabetes. Our findings suggest that Ampkα2 T172 activation is critical for exercise performance and energy transduction in skeletal muscle and may serve as a therapeutic target for type 2 diabetes.
A ketogenic diet enhances aerobic exercise adaptation and promotes muscle mitochondrial remodeling in hyperglycemic male mice
Pattamaprapanont, Pattarawan; Nava, Roberto C.; Grover, Rea; Formato, Mia; Cooney, Eileen M.; Pinto, Ana Paula; Alves-Wagner, Ana B.; Das, Anamica; Guan, Yuntian; Annambhotla, Meghana; Acharya, Saanvi; Rivas, Donato A.; Lessard, Sarah J. (2025-12-01)
VO₂peak is a key health benefit of aerobic exercise; however, chronic hyperglycemia is associated with persistently low VO₂peak due to an impaired adaptive response to training. Here, we show that reducing blood glucose with a carbohydrate-restricted, high fat ketogenic diet can restore aerobic exercise adaptation in male mice with hyperglycemia. Hyperglycemic mice received standard high-carbohydrate chow (CHOW), which sustains high blood glucose; or a ketogenic diet (KETO), which normalizes blood glucose levels. After aerobic exercise training, improvements in VO₂peak are blunted in CHOW, but restored by KETO. Increased VO₂peak in KETO is associated with enhanced aerobic remodeling of skeletal muscle, including a more oxidative fiber-type and increased capillary density. Moreover, KETO induces exercise-independent effects on muscle mitochondrial remodeling and substrate selection, significantly increasing fatty acid oxidation and down-regulating glucose metabolism. We identify a ketogenic diet as a potential therapy to improve aerobic exercise adaptation in the growing population with hyperglycemia.
Concurrent increase in fatty acid oxidation and fatty acid synthesis: a unique metabolic state in a pig model of pediatric steatotic liver disease
Yadav, Ravi; Lima, Marta R. M.; McMillan, Ryan P.; Sunny, Nishanth E.; El-Kadi, Samer W. (American Physiological Society, 2025-11-18)
Steatotic liver disease (SLD) is a spectrum of chronic and progressive disorders. Although often associated with obesity, it can afflict individuals without obesity, including infants. We previously reported that neonatal pigs fed formulas enriched with medium-chain fatty acids (MCFAs), rather than long-chain fatty acids (LCFAs), developed steatosis by day 7 and steatohepatitis by day 14. Here, we examined hepatic regulation of lipolytic and lipogenic pathways and associated metabolic outcomes. Neonatal pigs (n = 18) were fed isocaloric formulas containing MCFAs or LCFAs for 7, 14, or 21 days. Transcript abundance of most lipolytic and lipogenic genes was greater in MCFA- than in LCFA-fed pigs, independent of feeding duration. Upregulation of lipolytic genes of MCFA-fed pigs corresponded with greater lauric (P = 0.04) and palmitic (P = 0.03) acid oxidation, and greater plasma β-hydroxybutyrate concentrations than LCFA counterparts (P = 0.06). Upregulation of lipogenic genes in the MCFA group coincided with greater hepatic medium- (C12:0, C14:0) and long- (C16:0, C16:1) chain fatty acid concentrations (P < 0.05), and greater de novo lipogenic index at all time points (P < 0.001) compared with the LCFA group. Principal component and partial least squares analyses indicated that MCFA-fed pigs clustered with upregulated lipogenic, lipolytic, and transport genes, and were associated with greater medium-chain fatty acids and hepatic fat. However, LCFA-fed pigs clustered with greater polyunsaturated fatty acids and reduced transcript abundance of these genes. These findings demonstrate that pediatric SLD pathophysiology involves metabolic adaptations where fatty acid uptake and synthesis overwhelm the liver's oxidative or export capacity, causing net lipid accumulation.NEW & NOTEWORTHY We identify a distinct metabolic state in neonatal pigs with SLD. Contrary to the prevailing paradigm, disease development and progression to the more severe steatohepatitis occur despite enhanced hepatic fatty acid oxidation and the concurrent upregulation of both lipolytic and lipogenic gene expression. This paradoxical metabolic state, where increased fatty acid oxidation fails to prevent progressive steatosis, provides new insights into early-life SLD pathophysiology.
How yoga interventions are operationalized and reported in the context of mental health and wellbeing RCTs: a systematic review and qualitative synthesis
Frazier, Mary C.; Remskar, Masha; Harden, Samantha M.; Barley, Karsen S.; David, Danielle E.; Guillen, Marina Z.; Olsen, Daryn E.; Markley, Kayla M.; Pullin, Megan J.; Brinsley, Jacinta (2025-12-22)
Background: Yoga is a popular intervention demonstrating promising impacts for mental health and wellbeing. Despite growing research interest, yoga remains poorly operationalized and inconsistently described in scientific literature, hindering dissemination, rigorous evaluation, and replication. This systematic review aims to address this critical knowledge gap by examining how yoga is operationalized in recent mental health and wellbeing research. Methods: We conducted a systematic review of literature from January 2013 to August 2024. Terms relating to yoga, mental health, wellbeing, and interventions were used to search MEDLINE, CINAHL, Embase, Emcare, PsycINFO, and Scopus. Randomized controlled trials that included yoga as the primary intervention and reported a validated measure of mental ill-health, mental wellbeing, or quality of life, were included. Inductive qualitative analyses of yoga definitions and descriptions were conducted. Results: Of 5206 studies identified, 129 were included with exclusion primarily due to study design. Qualitative analysis resulted in a total of 1291 meaning units (MU). Yoga definitions suggest that yoga is operationalized as a practice, complementary and alternative medicine, or system (e.g., encompassing philosophy and practices) with mind-body or mind-body-spirit aspects. Components of yoga included physical such as postures, mental such as meditation, and breath. Conclusions: This is the first systematic review to comprehensively analyze how yoga is operationalised and reported in recent experimental mental health and wellbeing research. Generally, yoga is operationalized as a mind-body or mind-body-spirit practice comprising mental, physical, and breathing components. We provide recommendations to improve the translation and implementation of yoga interventions. Trial registration This study was prospectively registered with PROSPERO (CRD42023455373). Clinical trial number: not applicable.
Government Policies to Reduce Free or Added Sugars and Use Nonsugar Sweeteners Should Support Plant-Rich Dietary Patterns, a Healthy Microbiome and Planetary Health
Kraak, Vivica; Leary, Nicole A. (Elsevier, 2024-07)
Toward Safer Diagnoses: A SEIPS-Based Narrative Review of Diagnostic Errors
Yen, Carol; Epling, John W.; Rockwell, Michelle; Vaughn-Cooke, Monifa (MDPI, 2026-01-21)
Diagnostic errors have been a critical concern in healthcare, leading to substantial financial burdens and serious threats to patient safety. The Improving Diagnosis in Health Care report by the National Academies of Sciences, Engineering, and Medicine (NASEM) defines diagnostic errors, focusing on accuracy, timeliness, and communication, which are influenced by clinical knowledge and the broader healthcare system. This review aims to integrate existing literature on diagnostic error from a systems-based perspective and examine the factors across various domains to present a comprehensive picture of the topic. A narrative literature review was structured upon the Systems Engineering Initiative for Patient Safety (SEIPS) model that focuses on six domains central to the diagnostic process: Diagnostic Team Members, Tasks, Technologies and Tools, Organization, Physical Environment, and External Environment. Studies on contributing factors for diagnostic error in these domains were identified and integrated. The findings reveal that the effectiveness of diagnostics is influenced by complex, interconnected factors spanning all six SEIPS domains. In particular, socio-behavioral factors, such as team communication, cognitive bias, and workload, and environmental pressures, stand out as significant but difficult-to-capture contributors in traditional and commonly used data resources like electronic health records (EHRs), which limits the scope of many studies on diagnostic errors. Factors associated with diagnostic errors are often interconnected across healthcare system stakeholders and organizations. Future research should address both technical and behavioral elements within the diagnostic ecosystem to reduce errors and enhance patient outcomes.
What is online Supplemental Nutrition Assistance Program shopping worth? An implicit wage rate approach using meal-kit pricing and time-use data
Davis, George C.; Pierce, Timothy; Wilbur, Jessica; Yang, Jinyang (Cambridge University Press, 2025-04)
In 2023 all Supplemental Nutrition Assistance Program (SNAP) participants were allowed to start grocery shopping online. This paper provides the first answer to the question: What is online shopping worth to the SNAP participant in dollars? Using meal-kit pricing and time-use data, an implicit wage rate and dollar value distribution are estimated for time saved in home food production from online grocery shopping. We report the 95^th, 75^th, 50^th, 25^th, and 5^th percentile results. We simulate saving 50%, 75%, and 90% of grocery shopping time and estimate the savings per hour per meal. For example, if online shopping saved 75% of shopping time, the median saving per hour per meal would be $2.59. If a family of four made 15 to 30 meals a month, this corresponds to an implicit 5% to 11% increase in the benefits per month due to the time saved. The implicit wage rate provides simple and elegant economic insights into many aspects of food production and consumption not obtainable by just considering the money price.
Modest Caloric Surplus Combined With Resistance Training Leads To Healthy Weight Gain In Athletic Individuals
Sanchez, Allison D.; Reynolds, Jake C.; Marinik, Elaina L.; Davy, Brenda M.; Hunter, Gary R.; Larson-Meyer, D. Enette (Lippincott Williams & Wilkins, 2023-09)
Many athletes and military personnel desire weight gain ideally as lean mass to improve performance and effectiveness in sport and military endeavors. These athletes are commonly encouraged to increase energy intake by ~500 kcal/day with an emphasis on adequate protein (PRO) and carbohydrate (CHO), and judicious inclusion of healthy fat-containing calorically dense foods, including peanuts/peanut butter, along with rigorous resistance training (RT). These guidelines target gains of ~0.23 kg/wk. However, little is known about the efficacy of such regimens, particularly in female athletes. PURPOSE: To evaluate the outcomes of a 10-week (wk) diet and exercise regimen designed to promote healthy weight gain. METHODS: 32 male (N=19) and female (N=13) athletes (U.S. military, collegiate, club, firefighter, and recreational; previous RT experience) were randomly assigned to receive 500 additional kcal/day above weight maintenance diet through provision of either peanut-based whole foods/snacks (PRO group) or a similar, high-CHO, peanut-free snack (CHO group) along with a supervised RT regimen (3 days/wk for 60-120 minutes targeting major muscle groups). Body composition was assessed by dual-energy x-ray absorptiometry (DXA) at baseline, 3-wk, 7-wk, and post intervention. RESULTS: Total body mass (TBM) increased 2.1±1.2 kg (range of -0.9 to 4.4 kg) with 1.5±1.1 kg (range of -0.5 to 3.5 kg) as lean body mass (LBM) after 10-wk. The PRO group (N=16; 27±7 y; 10 men, 6 women) gained less TBM than the CHO group (N=16; 23±3 y; 9 men, 7 women) (1.6±1.1 kg vs 2.7±1.2 kg, respectively, p=0.008) and tended to gain less LBM (1.2±1.1 kg vs 1.9±1.0 kg, p=0.09). The age difference between the groups was significant (p=0.047). Men and women had a TBM gain of 2.0±1.3 kg and 2.4±1.1 kg (p=0.307) with a LBM gain of 1.3±1.1 kg and 1.9±1.0 kg (p=0.178), respectively. CONCLUSION: These results suggest that the addition of 500 kcal/day from whole foods/snacks in combination with a rigorous RT program promotes a similar weight gain of ~0.21 kg/wk, primarily as LBM, over 10-wk in both male and female athletes. However, age and/or snack macronutrient content may impact the effectiveness of this regimen.
The mGAINS Trial: Exploring The Feasibility And Utility Of Continuous Glucose Monitoring During Resistance Training
Reynolds, Jake C.; Sanchez, Allison D.; Marinik, Elaina L.; Dotson, Jon T.; Hunter, Gary R.; Larson-Meyer, D. Enette; Davy, Brenda M. (Lippincott Williams & Wilkins, 2023-09)
There is a growing interest in the use of continuous glucose monitoring (CGM) in the sport science field to inform training strategies and improve performance. These devices provide information on 24hr glucose control and glycemic variability (GV), which are associated with deleterious health outcomes independent from other measures of cardiometabolic health. Whether these devices are feasible and useful in the context of resistance training (RT) aimed at lean mass gain has yet to be explored. PURPOSE: To examine the feasibility of CGM use during RT and explore associations between 24hr glucose homeostasis, glycemic variability, and total body and lean mass gains in athletes participating in the mGAINS trial (Muscle Growth in Athletes In Combination with Nutritious Snacks) which combined RT with a modest energy surplus for 10 weeks. METHODS: 28 male (n=15) and female (n=13) athletes aged 25±6 y participated in a 10-week hypertrophy-based RT program (3 days/week, 60-120 min/d) and were provided a daily snack (500 kcal/snack) to be consumed in addition to their habitual diet. A CGM device was placed on the posterior side of the preferred arm (halfway between the olecranon and the acromion process) at baseline and during the last week of the RT intervention. Body composition was assessed using dual-energy x-ray absorptiometry at baseline and after training. RESULTS: Mean CGM wear period was 7±1 days at each time point. Device wear time active was 100%. After 10 weeks, total body mass increased by 2.1±1.3 kg with 1.5±1.1 kg as lean mass (both p<0.001). Mean 24hr glucose concentrations before and after the intervention were 88±9 (range: 66-107 mg/dl) and 90±11 (range: 72-113 mg/dL), respectively (p>0.05). Mean GV at the two time points was 18±3% (p>0.05). Change in 24hr glucose control was weakly/moderately associated with change in total body mass (r= -0.381, p=0.045), but the association between change in GV and change in lean mass did not reach significance (r= -0.351, p=0.067). CONCLUSION: CGM devices can be feasibly utilized during an intense RT program. An inverse correlation between total body mass gain and 24hr glucose concentrations may suggest that weight gained through RT in combination with a modest energy surplus improves 24hr glucose concentrations in athletes.
Change In Walking Economy After Resistance Training With Weight Gain In Young Adult Athletes
Marinik, Elaina L.; Sanchez, Allison D.; Reynolds, Jake C.; Hunter, Gary R.; Davy, Brenda M.; Larson-Meyer, D. Enette (Lippincott Williams & Wilkins, 2023-09)
Walking economy (WE) describes the relative efficiency to perform steady-state walking at a set submaximal intensity. Previous studies have demonstrated a positive effect of aerobic exercise, resistance training (RT), and weight loss on WE in various age groups of adults. However, the impact of weight gain during RT on WE has not been thoroughly investigated. Therefore, we explored the influence of RT combined with a modest caloric surplus intervention on WE in young adult athletes. PURPOSE:To examine changes in WE in young adult athletes after a 10-week RT and dietary intervention designed to promote healthy body mass gains. METHODS:28 athletes (16 male, 12 female; 25±6y) participated in a supervised, hypertrophy-focused RT program (3 days/week, 60-120 min/day) for 10 weeks, while consuming an extra 500 kcal/d from study-provided snacks. A steady-state WE treadmill test (4 min each at 3, 3.5, and 4 mph at a fixed 0% grade) using indirect calorimetry was performed at baseline and after RT. WE was calculated by averaging 15-sec values from the last 2 min of each stage. Body composition was measured by dual energy x-ray absorptiometry at both timepoints.
Repetitions In Reserve In Research: Analyzing The Relationship Of Strength And Loading Choices
Dotson, Jonathan T.; Reynolds, Jake C.; Sanchez, Allison D.; Marinik, Elaina L.; Davy, Brenda M.; Hunter, Gary R.; Larson-Meyer, D. Enette (Lippincott Williams & Wilkins, 2023-09)
Repetitions (reps) in reserve (RIR) is a practical method of quantifying resistance training (RT) intensity by estimating proximity to failure as a number of reps on a given set. RIR has long been employed in practice by strength athletes and trainers. Recently, it has become a subject of research—with initial studies supporting its effectiveness. Still, RIR relies on estimation. Gaining a better understanding of the effects which an individual’s strength and experience may have on their loading choice when using RIR will help inform future RT protocols in a research setting. PURPOSE: To examine how relative (RS) and absolute strength—as 1-repetition maximum (1RM)—affect loading choices for a given RIR by athletes in a research environment. METHODS: 16 male (n=10) and female (n=6) athletes aged 25±6 y were recruited to participate in a 10-week hypertrophybased RT program (3 days/week, 60-120 min/d). Participants were stratified by previous RT history as experienced (EX) or inexperienced (IX). Body weight (BW) was measured before the intervention. 1RM was tested in the back squat (BS) and bench press (BP) on week 2 and 10. Sub-maximal loading (determined by RIR) and a rep-range of 8–12 were used for the study’s remainder to promote muscle hypertrophy. 2 RIR and 3 RIR loading (as % of 1RM) was then compared to RS as determined by 1RM/BW. RESULTS: The average loading used in the BS and BP for 2 RIR was 83±11% and 80±9%, respectively. For 3 RIR, the loading was the same for both lifts at 68±6%. The average RS for BS and BP was 1.23±0.33 and 0.9±0.29 respectively. RS was strongly associated with resistance loading for 2 RIR and 3 RIR, respectively, in the BS (r= -0.757, p=0.001; r= -0.640, p=0.008) and BP (r= -0.794, p<0.001; r= - 0.722, p=0.002). 1RM was also strongly associated with 2 RIR and 3 RIR loading, respectively (BS: r= - 0.738, p=0.002; r= -0.670 p=0.005; and BP: r= - 0.756, p=0.001; r= -0.660, p=0.005). There were no differences in strength between EX and IX groups. CONCLUSION: These data suggest there is a strong inverse relationship between resistance loading choices at 2 RIR and 3 RIR (at a rep range of 8-12) and strength (both RS and 1RM) in an athletic population. Researchers employing RIR should be aware that an athlete’s strength may influence their likelihood to over- or underestimate RIR.
A Randomized Trial of Healthy Weight Gain in Athletic Individuals
Sanchez, Allison D.; Reynolds, Jake C.; Marinik, Elaina L.; Kolb, Ryann D.; Lozano, Alicia J.; Davy, Brenda M.; Hunter, Gary R.; Larson-Meyer, D. Enette (Lippincott, Williams & Wilkins, 2024-08-01)
Many athletes desire weight gain, ideally as lean body mass (LBM), to improve athletic performance. These athletes are commonly encouraged to increase energy intake by ∼500 kcal·d-1 with emphasis on adequate protein, carbohydrate, and judicious inclusion of healthy fat-containing energy-dense foods, such as peanuts/peanut butter, along with rigorous resistance training (RT). These guidelines target gains of ∼0.23 kg·wk-1. However, little is known about the efficacy of such regimens. Purpose The purpose of this study is to evaluate the outcomes of a 10-wk diet and exercise regimen designed to promote healthy weight gain with excess energy from peanut-containing or high-carbohydrate foods. Methods Nineteen male and 13 female athletes were randomly assigned to receive an additional 500 kcal·d-1 above typical intake through provision of either peanut-based whole foods/snacks (PNT group) or a similar, high-carbohydrate, peanut-free snack (CHO group) along with supervised, whole-body RT (3 d·wk-1 for 60-120 min). Body composition was assessed by dual-energyx-ray absorptiometry at baseline and postintervention. Results Total body mass (TBM) increased 2.2 ± 1.3 kg with 1.5 ± 1.1 kg as LBM after week 10. The PNT group (n = 16; 27 ± 7 yr; 10 men, 6 women) gained less TBM than the CHO group (n = 16; 23 ± 3 yr; 9 men, 7 women) (1.6 ± 1.1 kg vs 2.7 ± 1.2 kg, respectively, P = 0.007) with no differences in LBM (1.2 ± 1.1 kg vs 1.9 ± 1.0 kg, P = 0.136). Conclusions These results suggest that the addition of 500 kcal·d-1 from whole foods/snacks in combination with a rigorous RT program promotes a similar weight gain of ∼0.22 kg·wk-1, primarily as LBM, over 10 wk in both male and female athletes. However, snack macronutrient content may impact the effectiveness of this regimen.

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