ECSS Paris 2023: OP-PN28
INTRODUCTION: Cardiovascular disease (CVD) is the leading cause of death worldwide, although there are known sex-based differences until the age of menopause in women. Interestingly, the consumption of spicy peppers and their active ingredient, capsaicin, has been suggested to reduce CVD-related mortality, but whether this effect may be due to reductions in blood pressure (BP) and the underlying mechanisms remains unknown. Thus, the study of sex differences in not only peripheral BP, but Central BP and vascular stiffness which are relatively novel independent risk factors for CVD, and the acute effect of dietary capsaicin is warranted. As physical activity (PA) is recognized to reduce BP, it is imperative to match for this when making comparisons. Thus, we aimed to determine sex differences in the central and peripheral BP and vascular stiffness response to acute dietary capsaicin and potential differences in vasoactive biomarkers endothelin-1 (ET-1) and nitric oxide (NO) metabolites nitrite/nitrate (NOx), key regulators of vasomotor tone, vascular resistance, and thus BP. METHODS: In a randomized placebo-controlled crossover design, 40 young males (n=22, 21±2 yrs.) and females (n=18, 19±1 yrs.) were assessed for peripheral systolic (SBP) and diastolic (DBP) BP, central systolic (cSys), diastolic (cDia) BP, augmentation index normalized to 75 beats/min (AIx@75), and pulse wave velocity (PWV), in duplicate, using an automated oscillometric sphygmomanometer under placebo and capsaicin conditions. PA was self-reported and allowed for matching of men and women to control for the influence of PA on BP. Urine samples were obtained and analyzed for ET-1 and NOx using enzyme-linked immunosorbent or Griess reagent assays, respectively. Data were analyzed using two-way ANOVA. RESULTS: For peripheral BP, there was an interaction of sex*condition for SBP (p=0.028, η²p =0.201), where capsaicin lowered SBP in women but not men. Though directionally similar, no significant effects were noted in DBP (sex*condition, p=0.437, η²p =0.028). In central BP, no interaction effects were noted in central systolic (cSys, sex*condition, p=0.126, η²p =0.103) and diastolic BP (cDia, sex*condition, p=0.185, η²p =0.078), but again trended along the effects noted in SBP. AIx@75 was also similar (sex*condition, p=0.135, η²p =0.099), but not PWV (sex*condition, p=0.399, η²p =0.033). ET-1 was lower in women and tended to fall more so in women (sex*condition, p=0.187, η²p =0.045), though the opposite seemed true in NOx (sex*condition, p=0.099, η²p =0.070) and the ET-1:NOx ratio (sex*condition, p=0.245, η²p =0.035). CONCLUSION: Capsaicin lowered brachial SBP, where women responded favorably, with similar tendencies in cSys. While capsaicin tended to lower ET-1 in women, but not PA-matched men, and that NOx and the ET-1:NOx ratio do not exhibit this trend, suggests other mechanisms may be responsible, and warrants further study.
Read CV Stephen IvesECSS Paris 2023: OP-PN28
INTRODUCTION: The left atrium (LA) is responsible for modulating venous return and ventricular filling. Both pathological stimuli (e.g., hypertension, obesity, valvular disease) and endurance training (END) can influence LA structure and function. Clinically, an enlarged LA is associated with an increased risk of atrial fibrillation, including atrial dysrhythmias in some ultra-endurance athletes. Conversely, LA size is linked to higher cardiorespiratory fitness. Longitudinal studies of exercise-induced LA adaptations are limited, with existing research focused solely on END, demonstrating LA enlargement but sparse data on LA function. No studies have assessed LA adaptations to resistance training (RES) or utilized speckle-tracking echocardiography to evaluate mechanical function. Additionally, sex-specific changes to distinct exercise modalities have not been reported. METHODS: Sixty-four participants (26 male, 38 female) were randomized in a crossover designed study involving 12-weeks of END or RES, separated by a 12-week washout. LA structure and function were assessed using 2D and speckle tracking echocardiography. RESULTS: LAmax volume significantly increased following END (Delta 3.94±1.53mL, P=0.01) but not RES (Delta 2.68±1.54mL, P=0.07). The increase in LAmax volume following END was primarily due to a significant increase observed in males (Delta 6.19±2.27mL, P=0.007), not females (Delta 1.7±2.05, P=0.41). There was no significant change in LAmin volumes in response to training (END; Delta 1.03±0.85, P=0.23, RES; Delta -0.93±0.89, P=0.30), and no sex-dependent differences (all P>0.05). LA emptying fraction (LAEF) did not significantly change following END (Delta -1.21±1.54%, P=0.43), but significantly increased after RES (Delta 3.66±1.6%, P = 0.03), although no significant sex-dependent differences were apparent (all P>0.05). There were no significant training effects for either training type on LA reservoir, conduit, or contractile strain, nor sex-specific differences in these variables (all P>0.05). CONCLUSION: END significantly increased LAmax volume, primarily driven by adaptations in males, whereas RES had no significant effect. Conversely, RES improved LAEF, with no sex-specific differences. Neither training type altered indices of LA strain. These findings suggest that END induces structural LA remodelling, particularly in males, while RES enhances LA emptying. Given the higher prevalence of atrial fibrillation and the larger a priori LA structure apparent in men, the END related LA enlargement we observed in males may have implications for long-term management of cardiac arrythmias, particularly in ultra-endurance athletes.
Read CV Jesse CriddleECSS Paris 2023: OP-PN28
INTRODUCTION: Strenuous military field exercises (MFE) causes muscle mass loss and long-lasting physical performance impairments. However, their effect on muscle efficiency during submaximal work and associated cellular muscle changes are poorly understood. Furthermore, the effects of MFE in women are not well documented. This study aimed to investigate the impact of strenuous MFE on efficiency during submaximal work, muscle aerobic enzyme content, muscle glycogen content, and to identify potential sex differences in these aspects. METHODS: Efficiency was tested on a cycle ergometer (200 W for men and 150 W for women) and CMJ on a force plate in 10 men and in 8 women before (T0), and 1 (T1), 7 (T7), and 14 (T14) days after a 10-days MFE consisting of rigorous physical activity with food and sleep restriction. Muscle biopsies from m. vastus lateralis were collected at T0, T1, and T7. RESULTS: Countermovement jump height was decreased with 6.7±6.2% (p≤0.001) at T1 and was still decreased at T14 with 4.1±4.7% (p=0.003) for the sexes combined. There were no sex differences in the changes from T0 The men improved gross efficiency (GE) at T1 (0.7±0.7 pp, p=0.019), whereas it decreased in women (–0.9±1.0 pp, p=0.042). The change was different between sexes (p=0.002), and these group differences persisted at T7 (p=0.022). At T14, GE returned to pre-values in women, while it remained improved in men (0.4±0.6 pp, p=0.038), with no sex differences in the changes from T0. Heart rate (HR) decreased at T1 in both men (–12.9±3.4%, p≤0.001) and women (–4.6±4.7%, p=0.030), with a larger reduction in men (p≤0.001). HR remained reduced in men throughout recovery but returned to pre-values at T7 in women. Blood lactate concentration did not change significantly in either sex, though women showed a larger (p=0.037) non-significant increase at T1 (29±44%, p=0.198) compared to a non-significant decrease in men (–11±31%, p = 0.109). There were no sex differences in changes in respiratory exchange ratio or perceived exertion during submaximal cycling. At T7, the sexes combined reduced the content of citrate synthase (–23±28%, p=0.005) and tended to reduce to content of COX4 (–18±43%, p=0.056), with no sex differences. The changes in muscle glycogen content were similar in Type I and II fibers for both sexes. At T1, glycogen content in the muscle fibers combined was reduced in both men and women with 8±10% (p=0.033) and 8±8% (p=0.02), respectively. At T7, the percentage change from T0 was different between sexes (p=0.009), where the men had increased glycogen content with 10±6% (p≤0.001), while the women returned to T0 values. CONCLUSION: A demanding MFE resulted in improved cycling efficiency in men but impaired efficiency in women. The reasons for this sex difference remain unclear, though it is likely unrelated to changes in aerobic enzyme levels or glycogen stores, which were similar between men and women
Read CV Olav VikmoenECSS Paris 2023: OP-PN28