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Background: Conventional progressive concentric strengthening exercise (CSE) to improve bone mineral density (BMD) and bone mineral content (BMC) may not be feasible for populations with chronic musculoskeletal and/or metabolic conditions, such as osteoporosis or obesity. Muscle lengthening exercise, also known as an eccentric strengthening exercise (ESE), may have a special utility for those populations due to greater force generation versus CSE. In fact, greater mechanical loading can be induced on bone at lower resistance levels with ESE. However, effects of ESE on BMD and BMC are unclear. Thus, the purpose of this review was to interrogate the effects of ESE on BMD and BMC. Methods: A literature review was conducted between January 1995 and April 2022 focusing on randomized controlled trials investigating the effects of ESE on BMD and/or BMC in humans. Terms covering the domains of exercise, bone, and populations were searched on PubMed, CINAHL, and Scopus. The methodological quality of each interventional study was rated using Physiotherapy Evidence Database (PEDro) scale. Cohen's d was calculated to determine the magnitude of the effects of ERE on site-specific outcome measures of BMD and/or BMC. Results: Out of 1,182 articles initially found, a total of seven full length articles met our inclusion criteria. Of the seven studies, most of the interventions were performed in young (n = 5, PEDro = 5–7) versus middle-aged (n = 1, PEDro = 4) or older (n = 1, PEDro = 6) adults. BMD and BMC generally improved due to ESE; however the effects of ESE on BMD and BMC were non-homogenous. Effect size (d) ranged from 0.10–0.87 in young adults while it was 1.16 in older adults. Effect size (d) could not be calculated for the middle-aged adult study due to critical methodological limitations of the intervention. Conclusions: Large variability exists for the effectiveness of ESE on BMD/BMC across the human life spectrum. The benefits of ESE on BMD holds promise but rigorous studies are lacking. Further research is needed to examine if the dose, mode, age, and sex-specificity dictate effects of ESE on BMD/BMC. [ABSTRACT FROM AUTHOR]

Background: The number of exercise trials examining cardiometabolic outcomes in spinal cord injury (SCI) is low, and prescribed exercise is often inconvenient for individuals with SCI to perform within their community. Individuals with SCI experience a myriad of barriers to exercise participation, which can include a lack of time, accessible or usable equipment and facilities, and transportation. Thus, it is imperative to identify effective modes of exercise that provide the greatest overall health benefits but do not require a significant time commitment. Low-volume high intensity interval training (HIIT) has demonstrated the same improvements in cardiometabolic health as moderate intensity exercise training (MIT), despite only requiring 20% of the total time commitment in adults without disabilities and more recently in individuals with SCI.Objectives: The primary purpose of this study is to integrate a 16 week home-based telehealth HIIT arm crank exercise training program in individuals with SCI and assess changes in cardiometabolic health.Methods: Men and women between the ages of 19 and 60 with a confirmed diagnosis of SCI between C7 and T12 will be recruited for this study. Participants will be randomized to 16 weeks of telehealth HIIT exercise two days per week or a no-exercise control group. Aerobic capacity, muscular strength, blood lipids, glucose tolerance, resting energy expenditure, blood pressure, and body composition will be assessed at baseline and 16 weeks post-training.Discussion: Inactivity associated with SCI leads to chronic cardiometabolic health conditions. The majority of exercise interventions to date show that exercise is capable of increasing physical function, aerobic capacity, and muscle mass, and strength. Additionally, we have recently shown the ability of HIIT to improve blood lipid and glucose concentrations. Advances in telehealth exercise approaches have improved the capability to prescribe home-based exercise programs. Therefore, we hypothesize that the utilization of a home-based telehealth HIIT program will improve cardiometabolic health markers, yield high adherence (> 75%), and will be more enjoyable in individuals with SCI.Trial Registration: Telehealth High-Intensity Interval Exercise and Cardiometabolic Health in Spinal Cord Injury NCT04940598. [ABSTRACT FROM AUTHOR]

Purpose: To examine the effects of three different frequencies of combined resistance and aerobic training on total energy expenditure (TEE) and activity-related energy expenditure (AEE) in a group of older adults. Methods: Seventy-two women, 60-74 yr old, were randomly assigned to one of three groups: 1 d•wk-1 of aerobic training and 1 d•wk-1 of resistance training (1 + 1), 2 d•wk-1 of aerobic training and 2 d•wk-1 resistance training (2 + 2), or 3 d•wk-1 of aerobic training and 3 d•wk-1 of resistance training (3 + 3). Body composition (dual-energy x-ray absorptiometry), feeling of fatigue, depression, and vigor (questionnaire), strength (one-repetition maximum), serum cytokines (enzyme- linked immunosorbent assay), maximal oxygen uptake (progressive treadmill test), resting energy expenditure, and TEE were measured before and after 16 wk of training. Aerobic training consisted of 40 min of aerobic exercise at 80% maximum heart rate, and resistance training consisted of two sets of 10 repetitions for 10 different exercises at 80% of one repetition maximum. Results: All groups increased fat-free mass, strength, and aerobic fitness and decreased fat mass. No changes were observed in cytokines or perceptions of fatigue/depression. No time-group interaction was found for any fitness/body composition variable. TEE and AEE increased with the 2 + 2 group but not with the other two groups. Nonexercise training AEE (nonexercise training activity-related thermogenesis) increased significantly in the 2 + 2 group (+200 kcal•d-1), group 1 + 1 showed atrend for an increase (+68 kcal•d-1), and group 3 + 3 decreased significantly (-150 kcal•d-1). Conclusion: Results indicate that 3 + 3 training may inhibit nonexercise training activity- related thermogenesis by being too time consuming and does not induce superior training adaptations to 1 + 1 and 2 + 2 training. [ABSTRACT FROM AUTHOR]

Reduction of salivary nitrate to nitrite by oral nitrate reductase (NR) expressing bacteria has emerged as an integral pathway in regulating nitric oxide (NO) homeostasis and signaling. The oral microbiome is critical for this pathway. Variations in this pathway may underlie variable responses in the magnitude by which dietary or therapeutic nitrate modulates NO-signaling. The relationships between oral microbes and NR activity, and the factors that affect this relationship remain unclear however. Using a cross-sectional study design, the objective of this study was to determine the relationships between oral microbes and oral NR activity using a protocol that directly measures initial NR activity. Tongue swabs were collected from 28 subjects ranging in age from 21 to 73y. Initial NR activity showed a bell-shaped dependence with age, with activity peaking at ~40-50y and being lower but similar between younger (20-30y) and older (51–73) individuals. Microbiome relative abundance and diversity analyses, using 16s sequencing, demonstrated differences across age and identified both NR expressing and non-expressing bacteria in modulating initial NR activity. Finally, initial NR activity was measured in 3mo and 13mo old C57BL/6J mice. No differences in bacterial number were observed. However initial NR activity was significantly (80%) lower in 13mo old mice. Collectively, these data suggest that age is a variable in NR activity and may modulate responsiveness to dietary nitrate. • Age may be a variable in oral nitrate reductase activity and modulate responsiveness to dietary nitrate. • Oral nitrate reductase activity may be maximal in middle-age. • Middle age individuals may benefit most from nitrate-dependent interventions to stimulate nitric oxide bioactivity. [ABSTRACT FROM AUTHOR]

Background: Exercise training improves health outcomes in individuals with obesity (IO); however, it remains challenging for IO to adhere to exercise. Thus, it is critical to identify novel strategies that improve exercise tolerance (ET) and adherence in IO. Beetroot juice (BRJ), high in inorganic dietary nitrate, consistently improves exercise performance in athletes, individuals with cardiopulmonary diseases, and nonobese lean individuals. These improvements may be explained by reduced oxygen uptake (VO2) during exercise, enhanced blood flow, and greater mitochondrial efficiency. To date, we are aware of no studies that have compared the effects of BRJ, sodium nitrate (NaNO3), and nitrate‐depleted BRJ (PLA) for improving ET and cardiometabolic health in IO. Purpose: Determine if BRJ improves ET, exercise efficiency (EE), and cardiometabolic health in IO and identify possible mechanisms of action. Methods: Vascular hemodynamic, submaximal‐ and maximal‐exercise VO2, and time to exhaustion (TTE) were assessed in 16 participants 2.5 hr following consumption of: 1) BRJ, 2) NaNO3, 3) PLA, or 4) CON. Results: A significant treatment effect was observed for submaximal exercise VO2 (p =.003), and TTE (p <.001). Post hoc analyses revealed lower VO2 during submaximal exercise in BRJ compared to PLA (p =.009) NaNO3 (p =.042) and CON (0.009), equating to an average improvement of ~ 7% with BRJ. TTE was greater for BRJ compared to other treatment arms, PLA (p =.008), NaNO3 (p =.038), and CON (p=<0.001), equating to ~ 15% improvement with BRJ. No significant changes were observed for other outcomes. Conclusions: Consumption of BRJ improved EE during submaximal exercise by 7%, and TTE by 15% compared to other conditions. These results suggest that BRJ may improve EE and exercise tolerance in IO. [ABSTRACT FROM AUTHOR]

Hunter, GR, Neumeier, WH, Chandler-Laney, PC, Carter, SJ, Borges, JH, Hornbuckle, LM, Plaisance, EP, and Fisher, G. Ratings of perceived exertion during walking predicts endurance independent of physiological effort in older women. J Strength Cond Res 34(5): 1340-1344, 2020 This study aimed to determine whether ratings of perceived exertion (RPE) and physiological effort at different exercise intensities relate to exercise endurance. Ninety-eight sedentary women (older than 60 years) completed 3 submaximal locomotion tasks: (a) stair climbing, (b) flat walking at 2 mph, and (c) grade walking at 2 mph. Maximal treadmill endurance was measured at least 3 days before the submaximal tests.Oxygen uptakewas measured during all tests, and RPE were collected for the submaximal tasks. Ratings of perceived exertion during moderate-intensity exercise (walking on the flat at 43% VO2max, partial R=20.35, p,<0.01), but not higher intensity exercise (grade walk at 59%VO2max, p = 0.49, and stair climbing at 67% VO2max, p = 0.17), were related to endurance even after adjusting for aerobic capacity and physiological effort (composite of maximal heart rate, ventilation, and respiratory exchange ratio). However, physiological effort was significantly related to endurance for the higher intensity exercise (both grade walk and stair climbing partial R .>; −0.24, p ,< 0.02). Similar to previous findings that subjective ratings of fatigue at rest were related to RPE during low/moderateintensity exercise, but not higher intensity exercise, these data further support Ekkekakiss dual-mode hypothesis that cognitive factors influence RPE during low∕moderate-intensity exercise. A practical application is that the coach and personal trainer should know that physiological effort seems to play a greater role in influencing endurance than RPE as intensity of exercise increases [ABSTRACT FROM AUTHOR]

Introduction/Purpose: Aerobic exercise training (AET) has been shown to improve mitochondrial bioenergetics and upregulate proteins related to lipid metabolism. However, it remains to be determined if these alterations associated with AET persist when measured in energy balance (EB) in the days after the last bout of training. The purpose of the study was to test the hypothesis that improvements in skeletal muscle mitochondrial function induced by AET observed in previous literature would persist when measured after restoring EB conditions 72 h removed from the last exercise bout. Methods: Participants were 14 premenopausal women (age = 31.2 ± 6.7 yr, BMI = 26.6 ± 5.1 kg·m−2). The AET program required three monitored training sessions per week for 8–16 wk. Skeletal muscle biopsies were obtained at baseline and after 8–16 wk of AET (≥72 h after the last exercise bout). All food was provided for 72 h before biopsies, and EB was managed 24 h before testing within ±100 kcal of measured energy requirements using a whole-room calorimeter. Mitochondrial oxidative capacity was quantified in permeabilized muscle fibers from the vastus lateralis. Results: We found that AET increased coupled respiration (154%) and uncoupled respiration (90%) rates using a fatty acid substrate (palmitoyl carnitine) (P < 0.05). However, when rates were normalized to complex IV activity (a marker of mitochondrial content), no significant differences were observed. In addition, there were no changes in proteins known to mediate mitochondrial biogenesis or lipid transport and metabolism after AET. Conclusion: Eight to 16 wk of AET improved mitochondrial capacity under fatty acid substrate when assessed in EB, which appears to be due to mitochondrial biogenesis. [ABSTRACT FROM AUTHOR]

Sarcopenia not only affects the ability to lead an active lifestyle but also contributes to increased obesity, reduced quality of life, osteoporosis, and metabolic health, in part due to reduced locomotion economy and ease. On the other hand, increased obesity, decreased quality of life, and reduced metabolic health also contribute to sarcopenia. The purpose of this mini-review is to discuss the implications sarcopenia has for the development of obesity and comorbidities that occur with aging. [ABSTRACT FROM AUTHOR]