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.

Effects of dietary nitrate supplementation on muscular 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 its potential ergogenic effects across various population groups. This narrative review discusses the potential influence of different dietary nitrate supplementation strategies on nitric oxide bioavailability and muscular power output in healthy adults, athletes, older adults and some clinical populations. Areas for further research are also recommended including a focus individualized nitrate dosing regimens to optimize nitric oxide bioavailability and to promote muscular power enhancements in different populations.

Dyspnea Is Attenuated by Auditory Distraction via Music with Headphones during Exercise in Healthy Individuals.

PURPOSE: This study aimed to determine whether listening to music through headphones (a) affects the sensory (breathing intensity [BI]) and/or affective (breathing unpleasantness [BU]) components of dyspnea during exercise at different intensities and (b) affects exercise performance. METHODS: Twenty-two recreationally active individuals (24 ± 3 yr, 10 women) performed two 5-min constant loads (10% below/above gas exchange threshold [GET]) and an 8-km cycling time trial with ambient laboratory noise or self-selected music in a randomized crossover design. BI, BU, and ventilation ( V̇E ) were measured at each minute of the constant loads and every 2 km of the time trial. Ratios of BU/ V̇E and BI/ V̇E were used to examine the gain in dyspnea during the time trial. RESULTS: In the 10% below GET trial, BU was reduced in the first ( P = 0.03) and final ( P = 0.04) minutes. In the 10% above GET trial, BU and BI were reduced with music ( P < 0.05). During the time trial with music, BU/ V̇E was significantly attenuated by 9%-13% ( P < 0.05) despite a greater heart rate and self-selected power output ( P < 0.05). CONCLUSIONS: Music through headphones mitigated the sensation of dyspnea and changed the accretion of dyspnea per unit increase in V̇E leading to a higher self-selected workload during self-paced exercise. The dyspnea-reducing intervention of self-selected music may improve exercise tolerance and performance and promote adherence to regular aerobic exercise.

Functional Status, Mood State, and Physical Activity Among Women With Post-Acute COVID-19 Syndrome.

Objectives: While organ-specific pathophysiology has been well-described in SARS-CoV-2 infection, less is known about the attendant effects on functional status, mood state and leisure-time physical activity (PA) in post-acute COVID-19 syndrome (PASC). Methods: A case-control design was employed to recruit 32 women (n = 17 SARS-CoV-2; n = 15 controls) matched on age (54 ± 12 years) and body mass index (27 ± 6 kg/m2) that did not differ by smoking status or history of cardiopulmonary disease. Participants completed a series of assessments including Profile of Mood States (POMS), Modified Pulmonary Functional Status and Dyspnea Questionnaire (PFSDQ-M), and Godin-Shephard Leisure-Time PA. Results: Significant between-group differences were detected for the POMS total mood disturbance with sub-scale analyses revealing elevated tension, confusion, and lower vigor among SARS-CoV-2 participants (all p-values < 0.05). The number of SARS-CoV-2 symptoms (e.g., loss of taste/smell, muscle aches etc.) were associated (r = 0.620, p = 0.008) with confusion. SARS-CoV-2 participants exhibited poorer functional status (p = 0.008) and reduced leisure-time PA (p = 0.004) compared to controls. Conclusion: The sequela of persistent SARS-CoV-2 symptoms elicit clear disturbances in functional status, mood state, and leisure-time PA among women with PASC. Ongoing symptom presentation affects recovery time-course and PA participation.

More questions than answers for the use of inhaled nitric oxide in COVID-19.

Inhaled nitric oxide (iNO) is a potent vasodilator approved for use in term and near-term neonates, but with broad off-label use in settings including acute respiratory distress syndrome (ARDS). As an inhaled therapy, iNO reaches well ventilated portions of the lung and selectively vasodilates the pulmonary vascular bed, with little systemic effect due to its rapid inactivation in the bloodstream. iNO is well documented to improve oxygenation in a variety of pathological conditions, but in ARDS, these transient improvements in oxygenation have not translated into meaningful clinical outcomes. In coronavirus disease 2019 (COVID-19) related ARDS, iNO has been proposed as a potential treatment due to a variety of mechanisms, including its vasodilatory effect, antiviral properties, as well as anti-thrombotic and anti-inflammatory actions. Presently however, no randomized controlled data are available evaluating iNO in COVID-19, and published data are largely derived from retrospective and cohort studies. It is therefore important to interpret these limited findings with caution, as many questions remain around factors such as patient selection, optimal dosing, timing of administration, duration of administration, and delivery method. Each of these factors may influence whether iNO is indeed an efficacious therapy - or not - in this context. As such, until randomized controlled trial data are available, use of iNO in the treatment of patients with COVID-19 related ARDS should be considered on an individual basis with sound clinical judgement from the attending physician.

High Intraindividual Variability in the Response of Serum Erythropoietin to Multiple Simulated Altitude Exposures.

Baranauskas, Marissa N., Timothy J. Fulton, Alyce D. Fly, Bruce J. Martin, Timothy D. Mickleborough, and Robert F. Chapman. High intraindividual variability in the response of serum erythropoietin to multiple simulated altitude exposures. High Alt Med Biol. 23:85-89, 2022. Purpose: To evaluate within-subject variability in the serum erythropoietin (EPO) response to multiple simulated altitude exposures. Methods: Seven physically active men and women (age 27 ± 3 years, body mass index = 24.6 ± 4.0 kg/m2) were exposed to normobaric hypoxia (fraction of inspired oxygen [FiO2] = 0.14) for 12 hours on three separate occasions. Serum EPO concentrations were measured before exposure (0 hour), after 6 hours, and after 12 hours in hypoxia. The EPO response to hypoxia was calculated as percent change from 0 to 12 hours (ΔEPO0-12). Results: Exposure time had a significant effect on EPO (p < 0.001) with concentrations increasing 3.2 ± 1.3 mIU/ml from 0 to 6 hours (p = 0.034) and 4.7 ± 1.2 mIU/ml from 0 to 12 hours (p = 0.001). Group mean ΔEPO0-12 remained unchanged (p = 0.688) between the three exposures; however, there was considerable intraindividual variability in EPO responses. The intrasubject coefficient of variation for ΔEPO0-12 was 61% ± 28% (range: 17%-103%) with intrasubject associations ranging r = 0.052 to r = 0.651 between repeated exposures. Conclusions: Athletes who routinely supplement training with simulated altitude methods (e.g., hypoxic tents) should expect inconsistent EPO responses to intermittent exposures lasting ≤12 hours.

Why obesity and psychological stress matter in recovery of post-acute sequelae of SARS-CoV-2.

Numerous elements of the COVID-19 pandemic have proven challenging to overcome. We now recognize a perplexing characteristic of SARS-CoV-2 features mixed, unresolving symptoms that can last 4 weeks or longer after initial diagnosis, termed post-acute sequelae of SARS-CoV-2 (PASC). Full recovery can thus become a protracted ordeal as conservative estimates indicate 20% of SARS-CoV-2 cases will develop PASC, with women at increased risk. Emerging evidence suggests latent virus reactivation including cytomegalovirus, Epstein-Barr virus, and/or varicella zoster virus may perpetuate the burden of PASC. This is problematic because immune dysfunction is linked to obesity and psychological stress, both of which disproportionately affect socioeconomically disadvantaged people and racial/ethnic minorities. Applying a patient-centered approach in which the principal factors guiding decision-making are based on the needs and abilities of the individual is essential. Still, the independent and combined influence of obesity and psychological stress on immune function necessitates due consideration in the context of PASC recovery.

ARTE index revisited: linking biomarkers of cardiometabolic health with free-living physical activity in postmenopausal women.

Activity-related energy expenditure (AEE) correlates with physical activity volume; however, between-person differences in body size and walking economy (net V̇o2) can influence AEE. The ratio of total energy expenditure (TEE) and resting energy expenditure (REE) estimates physical activity level (PAL) relative to body mass, yet does not account for variance in walking economy. The activity-related time equivalent (ARTEwalk) circumvents such constraints by adjusting for individual-specific walking economy. Herein, we compared AEE, PAL, and ARTEwalk index in a cohort (n = 81) of postmenopausal women while examining possible associations with biomarkers of cardiometabolic health. Secondary analyses were performed on postmenopausal women dichotomized above/below age group 50th percentile for body fat percent. TEE was reduced by 10% for the thermogenesis of digestion wherein AEE was calculated by subtracting REE from adjusted TEE. PAL was calculated as the ratio of TEE/REE. AEE was divided by the mean net energy expenditure of nongraded walking to calculate the ARTEwalk index. Between-group differences were not detected for AEE or PAL. However, the ARTEwalk index revealed that participants with less adiposity were more physically active (258 ± 149 vs. 198 ± 115 min·day-1; P = 0.046; g = 0.46). AEE and PAL did not correlate with cardiorespiratory fitness or biomarkers of cardiometabolic health. Cardiorespiratory fitness (r = 0.32), arterial elasticity (r = 0.24), total cholesterol/HDL-c ratio (r = -0.22), and body fat% (r = -0.24) were correlated with ARTEwalk. The ARTEwalk index may offer utility in detecting possible differences in physical activity volume among postmenopausal women and appears better associated with cardiometabolic biomarkers compared with AEE or PAL.

Functional status, mood state, and physical activity among women with post-acute COVID-19 syndrome.

OBJECTIVES: While organ-specific pathophysiology has been well-described in SARS-CoV-2 infection, less is known about the attendant effects on functional status, mood state and leisure-time physical activity (PA) in post-acute COVID-19 syndrome. METHODS: A case-control design was employed to recruit 32 women ( n = 17 SARS-CoV-2; n = 15 controls) matched on age (54 ± 12 years), body mass index (27 ± 6 kg/m 2 ), smoking status, and history of cardiopulmonary disease. Participants completed a series of assessments including the Modified Pulmonary Functional Status and Dyspnea Questionnaire (PFSDQ-M), Profile of Mood States (POMS), and Godin-Shephard Leisure-Time PA. RESULTS: SARS-CoV-2 participants exhibited poorer functional status ( p = 0.008) and reduced leisure-time PA ( p = 0.004) compared to controls. Significant between-group differences were also detected for the POMS total mood disturbance with sub-scale analyses revealing elevated tension, confusion, and lower vigor among SARS-CoV-2 participants (all p -values < 0.05). The number of SARS-CoV-2 symptoms (e.g., loss of taste / smell, muscle aches etc.) were associated ( r = 0.620, p = 0.008) with confusion. CONCLUSION: The sequela of persistent SARS-CoV-2 symptoms elicit clear disturbances in functional status, mood state, and leisure-time PA among women with post-acute COVID-19 syndrome.

World Championship and Olympic Games Experience Influences Future Medal Performance in Track-and-Field Athletes.

Some track-and-field national governing bodies send athletes to World Championship and Olympic Games (WC/OG) to gain experience that may positively impact future success, even though athletes may not be expected to place high or medal. However, it is unclear if this strategy is advantageous for future medal attainment. PURPOSE: To determine if participation and/or advancement at a track-and-field athlete's first WC/OG influences the odds of future medaling. METHODS: Performances of US track-and-field athletes who made their first WC/OG team during 2000-2013 were tracked through 2016 to stratify athletes into categories. Athletes who medaled on their first team or never made a subsequent team (ie, no experience) were compared with athletes who did not medal on their first team but made subsequent teams (ie, experience). The experience group was further divided into athletes who advanced or did not advance out of the initial round at their first competition for a secondary analysis. Odds ratios (ORs) were calculated using logistic regression to measure the association between experience level and medaling. RESULTS: A significant OR was obtained for advanced versus did not advance (OR = 2.29, 95% confidence interval, 1.07-4.89, P = .03), but not for experience versus no experience (OR = 1.04, 95% confidence interval, 0.60-1.78, P = .91) group. CONCLUSIONS: Advancing out of the initial round of competition during an athlete's first WC/OG competition is associated with increased odds of future medaling. National governing bodies should consider this "experience threshold" during team selection processes.

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

NEW FINDINGS: What is the central question of this study? Are chronotropic responses to a 6-minute walk test different in women with post-acute coronavirus disease 2019 (COVID-19) syndrome compared with control subjects? What is the main finding and its importance? Compared with control subjects, the increase in heart rate was attenuated and recovery delayed after a 6-minute walk test in participants after infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Women reporting specific symptoms at time of testing had greater impairments compared with control subjects and SARS-CoV-2 participants not actively experiencing these symptoms. Such alterations have potential to constrain not only exercise tolerance but also participation in free-living physical activity in women during post-acute recovery from COVID-19. ABSTRACT: 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.

Moving beyond inclusion: Methodological considerations for the menstrual cycle and menopause in research evaluating effects of dietary nitrate on vascular function.

Recent reports have acknowledged the underrepresentation of women in the field of dietary nitrate (NO3-) research. Undoubtedly, greater participation from women is warranted to clarify potential sex differences in the responses to dietary NO3- interventions. However, careful consideration for the effects of sex hormones - principally 17ß-estradiol - on endogenous nitric oxide (NO) synthesis and dietary NO3- reductase capacity is necessary for improved interpretation and reproducibility of such investigations. From available literature, we present a narrative review describing how hormonal variations across the menstrual cycle, as well as with menopause, may impact NO biosynthesis catalyzed by NO synthase enzymes and NO3- reduction via the enterosalivary pathway. In doing so, we address methodological considerations related to the menstrual cycle and hormonal contraceptive use relevant for the inclusion of premenopausal women along with factors to consider when testing postmenopausal women. Adherence to such methodological practices may explicate the utility of dietary NO3- supplementation as a means to improve vascular function among women across the lifespan.

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). Sub-group 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.

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.

Stretch-Shortening Cycle Potentiation and Resistance Training-Induced Changes in Walking Economy/Ease and Activity-Related Energy Expenditure in Older Women.

ABSTRACT: Hunter, GR, Singh, H, Martins, C, Baranauskas, MN, and Carter, SJ. Stretch-shortening cycle potentiation and resistance training-induced changes in walking economy/ease and activity-related energy expenditure in older women. J Strength Cond Res 35(5): 1345-1349, 2021-Use of elastic energy to improve economy and ease of walking may be important for older adults. The purpose of this investigation was to determine whether baseline (i.e., untrained) stretch-shortening cycle potentiation (SSCP) was associated with potential changes in free-living activity-related energy expenditure (AEE) after supervised exercise training. Sedentary, postmenopausal women (n = 64) between 60 and 74 years of age were evaluated before and after 16 weeks of combined aerobic and resistance training. Assessments included: (a) body composition (dual-energy X-ray absorptiometry), (b) resting energy expenditure (indirect calorimetry), (c) submaximal and maximal walking (treadmill/indirect calorimetry), (d) total energy expenditure (doubly labeled water), and (e) one repetition maximum performed on an incline leg press and SSCP (calculated as the difference between concentric and countermovement leg press throw). Results indicated that baseline SSCP was related (r = -0.29; p < 0.02) to changes in AEE. However, subjects who possessed a high baseline SSCP did not increase SSCP or AEE, whereas subjects with low to moderate baseline SSCP demonstrated a significant increase in both SSCP (low +0.54 and moderate +0.47 m·s-1) and AEE (low +158 and moderate +333 kcal·d-1) post-training (all p less than 0.05). Our findings suggest that among subjects with low to moderate baseline SSCP, 16 weeks of combined aerobic and resistance training can increase SSCP and free-living AEE. However, subjects with high baseline SSCP may require tailored exercise to increase SSCP and possibly AEE.

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.

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).

Exercise Performance Is Impaired during the Midluteal Phase of the Menstrual Cycle.

PURPOSE: This study aimed to test the hypothesis that aerobic exercise performance is impaired in the midluteal (ML) compared with the midfollicular (MF) phase of the menstrual cycle. METHODS: Twelve recreationally active eumenorrheic women (25 ± 6 yr) completed exercise sessions during the MF and the ML phases. Each session consisted of an 8-km cycling time trial that was preceded by 10 min of cycling performed at a constant power below and above gas exchange threshold. Heart rate, ventilation, and oxygen uptake were continuously measured. RPE and ratings of fatigue were assessed during the time trial using visual analog scales. Total mood disturbance was calculated from the POMS questionnaire administered before and 20 min postexercise. RESULTS: Salivary progesterone concentration was 578 ± 515 pg·mL-1 higher in ML compared with MF phase (P < 0.01), whereas estradiol concentration did not differ between phases (167 ± 55 vs 206 ± 120 pg·mL-1, P = 0.31). Total mood disturbance before exercise was greater during the ML phase compared with the MF phase (P < 0.01), but this difference was abolished postexercise (P = 0.14). Mean power output was lower during the ML phase (115 ± 29 vs 125 ± 28 W, P < 0.01), which led to a slower time trial in the ML phase (18.3 ± 2.0 min) compared with the MF phase (17.8 ± 1.7 min, P = 0.03). Ratings of fatigue were greater during the ML phase from 2 to 8 km (P ≤ 0.01), whereas no differences in RPE were observed. Heart rate (P = 0.85), minute ventilation (P = 0.53), and oxygen uptake (P = 0.32) did not differ between phases during the time trial. CONCLUSION: Aerobic exercise performance is worse in the ML phase compared with the MF phase in recreationally active women, which was accompanied by a more negative mood state preexercise and increased ratings of fatigue.