Introduction: The scientific literature is characterized by a historical underrepresentation of the female population in sports science. A critical issue in the current literature is the inconsistency between objectively measured (e.g., time to exhaustion) and subjectively perceived performance across the menstrual cycle. This inconsistency is often attributed to methodological limitations (e.g., absence of hormonal assessments and ovulation kits) and to the lack of consideration of menstrual-related symptoms and psychological variables. Purpose: The primary objective of the study was to compare graded exercise test (GXT) performance outcomes across menstrual cycle phases. A secondary objective was to investigate whether cramp severity was associated with GXT performance during menses. A final objective was to examine the effects of menstrual cycle phase on psychological responses to exercise. Methods: Nineteen physically active eumenorrheic women (age 24 ± 4 years, V̇O 2peak 38.4 ± 3.1 mL·kg -1 ·min -1 ) completed five GXTs: two for familiarization and three performed during experimental sessions scheduled in three specific phases of the menstrual cycle (menses, follicular, and luteal). Variables of interest included estradiol and progesterone levels, affective valence, arousal, anxiety, heart rate, rating of perceived exertion, mood disturbance, and motivation. Exercise capacity was operationalized as GXT performance outcomes (peak power output [W peak ] and time to exhaustion). Cramp severity was measured only during menses. Results: No statistically significant differences in W peak or time to exhaustion were detected across menstrual cycle phases (p > 0.05). Secondary and exploratory regression analyses indicated that each one-point increase in menstrual cramp severity during menses was associated with lower GXT performance (W peak : -1.50 W; time to exhaustion: 2.72 s; p = 0.04; R 2 = ~0.35). Higher affective valence scores were associated with improved W peak (+4.27 W) and time to exhaustion (-8.51 s; p = 0.02; R 2 = ~0.36), whereas higher arousal scores were associated with lower W peak (-11.40 W) and higher time to exhaustion (6.47 s; p = 0.01; R 2 = ~0.46) across the menstrual cycle. Motivation was lower during menses than during the follicular phase (p = 0.04). Conclusions: No statistically significant differences in GXT performance were detected across menstrual cycle phases. However, secondary and exploratory analyses suggest that greater menstrual cramp severity during menses was associated with lower time to exhaustion and W peak . These findings provide preliminary evidence that menstrual-related symptoms and psychological factors may contribute to variability in GXT performance outcomes and warrant further investigation in larger cohorts.
Purpose: The systolic blood pressure (SBP) response to moderate-to-vigorous intensity exercise (xSBP) is associated with cardiovascular health and future disease. We investigated the relationship between exercise intensity and xSBP and generated reference values for xSBP for healthy Americans performing moderate-to-vigorous intensity treadmill exercise. Methods: We analyzed data from 7,447 healthy participants, aged 12–49 years, in the 1999–2004 National Health and Nutrition Examination Survey (NHANES). Participants completed two 3-minute treadmill stages eliciting ~64% and ~76% of their estimated maximum heart rate (%HR MAX ). SBP was measured during the third minute of each stage. Absolute work rate (metabolic equivalents, MET) was estimated from treadmill speed and grade. Mixed-model ANOVA accounting for the complex survey design was used. Results: Sex-specific normative values for xSBP and xSBP indexed to work rate were generated. Age was only weakly related to xSBP (r = -0.019 to -0.024, P<0.001), so data were not stratified by age. Overall, males exhibited significantly greater increase in SBP at Stage 1 and Stage 2 (~22 and ~27 ΔmmHg, respectively; P<0.0001). Absolute work rate ( i.e., MET) was related to xSBP (r = 0.404 to 0.494, P<0.001). Accounting for differences in resting SBP (rSBP) and MET blunted but did not eliminate the sex difference in xSBP (P<0.0001). Furthermore, males exhibited a greater increase in SBP per MET than females (+5.58 ± 0.47 ΔmmHg·ΔMET -1 , P<0.0001). Conclusions: Biological sex and absolute work rate are independently associated with the blood pressure response to moderate-to-vigorous intensity exercise. The sex-stratified, absolute, and work-indexed reference values generated in this study provide context for interpreting exercise blood pressure in clinical and research settings.
Purpose: Skeletal muscle degeneration, which includes atrophy and intramuscular fat infiltration, is widely observed in individuals with knee osteoarthritis (OA). Although these changes in muscle volume and internal properties are likely accompanied by alterations in three-dimensional (3D) muscle shape, it remains largely understudied. This study aimed to determine variations in 3D muscle shape in individuals with knee OA using statistical shape modeling. Methods: Forty patients with knee OA and 51 control individuals underwent magnetic resonance imaging via T1-weighted and Dixon methods to examine volume and intramuscular fat of the quadriceps femoris. The 3D muscle shape was quantified using statistical shape models based on the principal components. Muscle volume, intramuscular fat content, and shape were compared between knee OA individuals and controls. Logistic regression analysis was used to distinguish individuals with knee OA from controls based on muscle volume, intramuscular fat, and shape, respectively. Results: Individuals with knee OA presented not only volume loss and intramuscular fat accumulation but also muscle shape changes in the vastus medialis and intermedius. The vastus medialis exhibited a flattened shape and anterior edge shrinkage, whereas the vastus intermedius presented anterior bulging along the length in the knee OA group; these were specific morphological changes associated with knee OA. These muscle deformations were compared to the degree of volume loss and intramuscular fat accumulation to accurately distinguish individuals with knee OA from controls, outperforming classifications based on volume and intramuscular fat. Conclusions: Our findings demonstrate muscle deformation of vastus medialis and vastus intermedius in individuals with knee OA, providing new insights into muscle morphological changes and their potential relevance as novel morphological biomarkers of knee OA.
Introduction: Repeated sprint training in hypoxia (RSH) or with blood flow restriction (RS-BFR) are known to enhance the repeated-sprint ability. However, studies directly comparing their underlying molecular mechanisms are scarce. Methods: Here we used a comprehensive approach combining pre- and post-intervention testing including sprint performance tests, neuromuscular assessments, skeletal muscle biopsies for protein levels quantification, and blood samples for systemic metabolites analyses to characterize the specific adaptations induced by RSH and RS-BFR. Recreationally active men performed 9 sessions of RSH (FiO₂ ~0.136; n=9) or RS-BFR (45% arterial occlusion; n=8). Results: Both RSH and RS-BFR similarly improved exercise performance without significant changes in knee extensor maximal voluntary contraction force. Both training modalities reduced the levels of oxidative phosphorylation proteins while increasing markers of mitochondrial dynamics and mitochondrial translation proteins. Glycolytic remodelling was evident in both groups, with increased levels of the glucose transporter 4 and phosphofructokinase proteins, accompanied by marked upregulation of the S100A13-Akt signalling. Unbiased muscle proteomics and plasma metabolomics also revealed common and more specific signatures. Both RSH and RS-BFR increased plasma levels of intermediates metabolites of lipid metabolism. RSH specifically upregulated cytoplasmic translation pathways in muscle and increased the kynurenate/kynurenine ratio in plasma, whereas RS-BFR was characterized by an upregulation of immune and inflammatory pathways both in muscle and plasma. Conclusions: In summary, 3-week of RS-BFR elicits performance adaptations comparable to RSH, supported by largely shared muscular and systemic metabolic adaptations. The specific characteristics of the adaptations induced by each method, however, are particularly interesting and could influence the outcome of regular training.
