Evidence for impaired chronotropic responses to and recovery from 6‐minute walk test in women with post‐acute COVID‐19 syndrome

The short-term cardiopulmonary manifestations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are well defined. However, the implications of cardiopulmonary sequelae, persisting beyond acute illness, on physical function are largely unknown. Herein, we characterized heart rate responses to and recovery from a 6-minute walk test (6MWT) in women ∼3 months after mild-to-moderate SARS-CoV-2 infection compared with non-infected control subjects. Forty-five women (n = 29 SARS-CoV-2; n = 16 controls; age = 56 ± 11 years; body mass index = 25.8 ± 6.0 kg/m2) completed pulmonary function testing and a 6MWT. The SARS-CoV-2 participants demonstrated reduced total lung capacity (84 ± 8 vs. 93 ± 13%; P = 0.006), vital capacity (87 ± 10 vs. 93 ± 10%; P = 0.040), functional residual capacity (75 ± 16 vs. 88 ± 16%; P = 0.006) and residual volume (76 ± 18 vs. 93 ± 22%; P = 0.001) compared with control subjects. No between-group differences were observed in 6MWT distance (P = 0.194); however, the increase in heart rate with exertion was attenuated among SARS-CoV-2 participants compared with control subjects (+52 ± 20 vs. +65 ± 18 beats/min; P = 0.029). The decrease in heart rate was also delayed for minutes 1–5 of recovery among SARS-CoV-2 participants (all P < 0.05). Women reporting specific symptoms at the time of testing had greater impairments compared with control subjects and SARS-CoV-2 participants not actively experiencing these symptoms. Our findings provide evidence for marked differences in chronotropic responses to and recovery from a 6MWT in women several months after acute SARS-CoV-2 infection

Potential health effects of dietary nitrate supplementation in aging and chronic degenerative disease

In the United States, latest projections indicate the number of adults 65 years of age and older is expected to double by 2050. Given that increased oxidative stress is a hallmark of aging, it is understandable that waning nitric oxide and chronic degenerative disease arise in tandem. To this end, translational evidence-based strategies are needed to mitigate the impending toll on personal and public health. Dietary nitrate supplementation, particularly in the form of beetroot juice, is an active area of inquiry that has gained considerable attention in recent years. Compelling evidence has revealed beetroot juice can elicit potent physiological responses that may offer associated health benefits for multiple clinical disorders including hypertension, dementia, and sarcopenia. Even in the absence of overt disease, age-related impairments in cardiovascular and skeletal muscle function may uniquely benefit from beetroot juice supplementation as evidence has shown blood pressure lowering effects and improved muscle function/contractility – presumably from increased nitric oxide bioavailability. This, in turn, presents a practical opportunity for susceptible populations to support ease of movement and exercise tolerance, both of which may promote free-living physical activity. A theoretical rationale details the potential health effects of dietary nitrate supplementation, wherein a working framework hypothesizes beetroot juice consumption prior to structured exercise training may offer synergistic benefits to aid healthy aging and independent-living among older adults

Exercise load monitoring: integrated approaches to advance the individualisation of exercise oncology

Whether slowing disease progression or combatting the ills of advancing age, the extensive utility of exercise training has contributed to the outright declaration by the American College of Sports Medicine that ‘exercise is medicine’. Consistent with general framework of adaptation, the advantages of exercise training are indiscriminate—benefitting even the most susceptible clinical populations. Still, the benefit of exercise training presupposes healthy adaptation wherein progressive overload matches sufficient recovery. Indeed, a difference exists between healthy adaptation and non-functional over-reaching (ie, when internal/external load exceeds recovery capacity)—a difference that may be blurred by cancer treatment and/or comorbidity. Recent advances in smartwatches make them ideally suited to non-invasively monitor the physiological stresses to exercise training. Resolving whether individuals are successfully adapting to exercise training via load monitoring bears clinical and practical relevance. While behaviour-change research aims to identify positive constructs of exercise adherence, further attention is needed to uncover how to optimise exercise prescription among cancer populations. Herein, we briefly discuss the constituents of exercise load monitoring, present examples of internal and external load and consider how such practices can be applied to cancer populations

Beetroot supplementation in women enjoying exercise together (BEE SWEET): Rationale, design and methods

Background: Postmenopausal women exhibit higher rates of disability and cardiovascular disease (CVD) with aging compared to men. Whereas habitual exercise training is a known strategy to enhance physiologic function in men and premenopausal women, exercise-related adaptations are often modest in postmenopausal women. We propose dietary nitrate (beetroot juice) administered prior to exercise training may be a feasible approach to improve mobility and cardio-metabolic health outcomes in postmenopausal women. Methods: Our randomized, placebo-controlled study aims to determine preliminary effects sizes for changes in functional mobility and endothelium-dependent vasodilation across three study arms: exercise only (EX), exercise + placebo (EX + PL), and exercise + beetroot (EX + BR). Thirty-six postmenopausal women are recruited in small cohorts wherein group exercise is implemented to facilitate social support and adherence to an 8-week training progression. Participants are randomized to one of three study arms (n = 12 per group) following baseline assessments. Post-intervention assessments are used to determine pre-post changes in outcome measures including distance covered during a 6 min walk test, walking economy, muscle speed and power, and endothelial-dependent vasodilation as determined by flow-mediated dilation. Measures of feasibility include recruitment, retention, adherence to exercise prescription, perceived exercise session difficulty, and adverse event rates. Discussion: Evidence-based, translational strategies are needed to optimize exercise training-related adaptations in postmenopausal women. Findings will inform larger randomized clinical trials to determine if pre-exercise consumption of beetroot juice is an efficacious strategy to promote mobility and attenuate CVD disease risk

Effect of dietary nitrate on human muscle power: a systematic review and individual participant data meta-analysis

Background: Previous narrative reviews have concluded that dietary nitrate (NO3−) improves maximal neuromuscular power in humans. This conclusion, however, was based on a limited number of studies, and no attempt has been made to quantify the exact magnitude of this beneficial effect. Such information would help ensure adequate statistical power in future studies and could help place the effects of dietary NO3− on various aspects of exercise performance (i.e., endurance vs. strength vs. power) in better context. We therefore undertook a systematic review and individual participant data meta-analysis to quantify the effects of NO3− supplementation on human muscle power. Methods: The literature was searched using a strategy developed by a health sciences librarian. Data sources included Medline Ovid, Embase, SPORTDiscus, Scopus, Clinicaltrials.gov, and Google Scholar. Studies were included if they used a randomized, double-blind, placebo-controlled, crossover experimental design to measure the effects of dietary NO3− on maximal power during exercise in the non-fatigued state and the within-subject correlation could be determined from data in the published manuscript or obtained from the authors. Results: Nineteen studies of a total of 268 participants (218 men, 50 women) met the criteria for inclusion. The overall effect size (ES; Hedge’s g) calculated using a fixed effects model was 0.42 (95% confidence interval (CI) 0.29, 0.56; p = 6.310 × 10− 11). There was limited heterogeneity between studies (i.e., I2 = 22.79%, H2 = 1.30, p = 0.3460). The ES estimated using a random effects model was therefore similar (i.e., 0.45, 95% CI 0.30, 0.61; p = 1.064 × 10− 9). Subgroup analyses revealed no significant differences due to subject age, sex, or test modality (i.e., small vs. large muscle mass exercise). However, the ES in studies using an acute dose (i.e., 0.54, 95% CI 0.37, 0.71; p = 6.774 × 10− 12) was greater (p = 0.0211) than in studies using a multiple dose regimen (i.e., 0.22, 95% CI 0.01, 0.43; p =0.003630). Conclusions: Acute or chronic dietary NO3− intake significantly increases maximal muscle power in humans. The magnitude of this effect–on average, ~ 5%–is likely to be of considerable practical and clinical importance

Amenorrhea and oligomenorrhea risk related to exercise training volume and intensity: Findings from 3,705 participants recruited via the STRAVA exercise application

The physiological underpinnings of amenorrhea/oligomenorrhea (AO) among exercising women are complex and incompletely understood. Objectives: To investigate associations between self-reported exercise training habits and AO among physically active women. Design: A cross-sectional survey was completed by 3,705 women (median age = 40 years [Quartile 1, Quartile 3: 30, 45], body mass index [BMI] = 22.1 kg/m2 [20.5, 24.2]) representing multiple nationalities and sports via the STRAVA exercise application. Respondents selected the amount of time they participated in low intensity (LIT), moderate intensity (MIT), and high intensity exercise training (HIT) domains per week. AO was defined as self-reporting 10 menses in the last year. Method: Associations between weekly exercise volume for LIT, MIT, and HIT and AO were modeled with univariate logistic regression models, followed by adjustment for age and BMI. Results: AO prevalence was 16% (n = 576/3,705), with no difference by country of origin or most sport modes. In adjusted models, participating in LIT 7 h/week or MIT 6 h/week was associated with 1.43 (95% CI:1.04 - 1.96) and 1.46 (1.10 - 1.95) greater odds of AO compared to 2 to 3 h/week, respectively. Similarly, HIT 5 h/week was associated with 1.41 (1.03 - 1.92) greater odds of AO compared to 1 to 2 h/week. Participating in LIT for 30 min/week compared to 2 to 3 h/week was associated with reduced AO odds (0.65 [95% CI: 0.44 – 0.94]). Conclusions: Taken together, these associations suggest greater weekly exercise volume, irrespective of intensity, may increase AO risk among habitually active women

Heat Versus Altitude Training for Endurance Performance at Sea Level

Environmental stressors, such as heat or altitude, elicit dissimilar physiological adaptations to endurance training programs. Whether these differences (i.e., increased hemoglobin mass vs plasma volume) differentially influence performance is debated. We review data in support of our novel hypothesis, which proposes altitude as the preferred environmental training stimulus for elite endurance athletes preparing to compete in temperate, sea-level climates (5°C-18°C)

Amenorrhea and oligomenorrhea risk related to exercise training volume and intensity: Findings from 3705 participants recruited via the STRAVA™ exercise application

Objectives: To investigate associations between self-reported exercise training habits and amenorrhea/oligomenorrhea among physically active women. // Design: A cross-sectional survey was completed by 3705 women (median age = 40 years [quartile 1, quartile 3: 30, 45], body mass index = 22.1 kg/m2 [20.5, 24.2]) representing multiple nationalities and sports via the STRAVA™ exercise application. Respondents selected the amount of time they participated in low intensity, moderate intensity, and high intensity exercise training per week. Amenorrhea/oligomenorrhea was defined as self-reporting ≤10 menses in the last year. // Methods: Associations between weekly exercise volume for low intensity training, moderate intensity training, and high intensity training and amenorrhea/oligomenorrhea were modeled with univariate logistic regression models, followed by adjustment for age and body mass index. // Results: Amenorrhea/oligomenorrhea prevalence was 16 % (n = 576/3705), with no difference by country of origin or most sport modes. In adjusted models, participating in low intensity training ≥7 h/week or moderate intensity training ≥6 h/week was associated with 1.43 (95 % confidence interval: 1.04–1.96) and 1.46 (1.10–1.95) greater odds of amenorrhea/oligomenorrhea compared to 2 to 3 h/week, respectively. Similarly, high intensity training ≥5 h/week was associated with 1.41 (1.03–1.92) greater odds of amenorrhea/oligomenorrhea compared to 1 to 2 h/week. Participating in low intensity training for ≤30 min/week compared to 2 to 3 h/week was associated with reduced amenorrhea/oligomenorrhea odds (0.65 [0.44–0.94]). // Conclusions: Taken together, these associations suggest greater weekly exercise volume, irrespective of intensity, may increase amenorrhea/oligomenorrhea risk among physically active women

Effects of dietary nitrate supplementation on peak power output: influence of supplementation strategy and population

Increasing evidence indicates that dietary nitrate supplementation has the potential to increase muscular power output during skeletal muscle contractions. However, there is still a paucity of data characterizing the impact of different nitrate dosing regimens on nitric oxide bioavailability and its potential ergogenic effects across various population groups. This review discusses the potential influence of different dietary nitrate supplementation strategies on nitric oxide bioavailability and muscular peak power output in healthy adults, athletes, older adults and some clinical populations. Effect sizes were calculated for peak power output and absolute and/or relative nitrate doses were considered where applicable. There was no relationship between the effect sizes of peak power output change following nitrate supplementation and when nitrate dosage when considered in absolute or relative terms. Areas for further research are also recommended including a focus on nitrate dosing regimens that optimize nitric oxide bioavailability for enhancing peak power at times of increased muscular work in a variety of healthy and disease populations.</p