ECSS Paris 2023: OP-PN32
INTRODUCTION: Eccentric (ECC) cycling allows greater mechanical load to be achieved despite lower metabolic demand [1] and induces different acute cardiorespiratory and neuromuscular responses than those observed during conventional concentric (CON) cycling [2-3]. The present study aimed to determine how pedal cadence and blood flow restriction (BFR) to the exercising limb affect acute cardiorespiratory, vascular and neuromuscular responses to ECC cycling. METHODS: Healthy males (n=10, 38±10y, BMI 24.0±2.5) completed 4 sessions over 4-wk. The first two sessions were used to familiarize the participants to procedures including single leg (SL) ECC cycling, maximal voluntary knee extensor isometric strength (MVC) and microvascular function tests (MVF) based on vastus lateralis (VL) oxygenation response to 5-min arterial occlusion/reperfusion. In addition, SL-CON cycling sprint power for 10-s at 20- and 60-rpm were measured. The following two visits consisted of 15 bouts of 40-s SL-ECC cycling at 25% SL-CON sprint power, with 20-s passive cycling recovery. One leg cycled with BFR (60% of arterial occlusion pressure) while the other cycled without (non-BFR). Cardiorespiratory function (indirect calorimetry and telemetry), VL oxygenation (near infra-red spectroscopy) and electromyographic activity (EMG) were continuously recorded. Blood lactate (BL), MVC and MVF were assessed before and after exercise. Two-way repeated measures ANOVAs were performed to test for cadence and BFR effects on the measures. All data are expressed as mean ± SD and a significant level was set at p<0.05. RESULTS: Mean power output was higher (p<0.001) at 60- (133±23W) than 20-rpm (57±11W) without difference between BFR and non-BFR conditions. Oxygen uptake (+58%), heart rate (HR, +15%), pulmonary ventilation (+28%) and breathing rate (BR, +25%) were greater during exercise at 60-rpm than 20-rpm (p<0.05). VE (+20%) and BR (+13%) were higher (p<0.05) in the BFR than non-BFR condition, while HR tended to be higher (+6%, p=0.066) with BFR than non-BFR. VL oxygenation was 6% lower at 60- than 20-rpm and also reduced by 16% in BFR compared to non-BFR condition (cadence effect p<0.01, BFR effect p<0.001). Post-exercise BL was not significantly altered by cadence but was 38% higher (p<0.05) in the BFR than non-BFR condition. There was no significant cadence nor BFR effects on EMG activity, MVC and MVF tests. CONCLUSION: These data suggest greater acute cardiorespiratory and muscle metabolic challenges when ECC cycling is performed at faster pedal cadence with BFR. Therefore, combining faster pedal cadence and BFR might be a useful strategy to enhance cardiorespiratory and muscle metabolic training stimuli for future chronic studies exploring the functional benefits of ECC cycling in clinical and athletic populations. 1. Dufour et al. Am J Physiol Regul Integr Comp Physiol. 2007 2. Barreto et al. J Sports Med Phys Fitness. 2023 3. Isner-Horobeti et al. Sports Med. 2013 SD was supported by a grant from Region Grand Est, France
Read CV Stéphane P. DufourECSS Paris 2023: OP-PN32
INTRODUCTION: Recently, it has been reported in young, trained males and males with obesity that in the moderate intensity domain of exercise, heart rate (HR) kinetics exhibit a slow component, distinct from oxygen uptake, which reaches a steady state at intensities below ventilatory threshold 1 (VT1). The functional significance of the slow component in at moderate intensity is unclear. The autonomous nervous system (ANS) is known to be the principal modulator of HR during exercise. Therefore, the aim of this study is to establish the relationship between HR variability, representing the ANS, and the HR kinetics in moderate intensity domain in normal weight persons and persons with grade 1 obesity. METHODS: Sixteen persons with grade I obesity (OB) of 27 ± 4 years old and sixteen age-matched normal weight persons (NW) were recruited. All volunteers visited the laboratory on two non-consecutive days. On the first day, resting HR variability was measured, and an incremental test was conducted to determine VT1. HR variability assessment involved calculation of low frequency (LF), very low frequency (VLF) and high frequency (HF) power and the ratio LF/HF. On second day, subjects performed three transitions from unloaded cycling to 70% of the load associated with VT1. HR was measured during each transition. HR kinetics were determined for each participant following the procedure described by Zuccarelli et al. (2018). One of three possible models: mono-exponential, biexponential, and exponential+linear) were fitted to the HR data. The frequency of each model in each group was compared using chi-squared analysis. Comparisons between groups were made using the Mann-Whitney test, and Spearmans test was used to establish correlations between variables. Statistical significance for all tests was set at p ≤ 0.05. Zuccarelli, L. et al. (2018). Comparison between Slow Components of HR and V&O2 Kinetics. Medicine & Science in Sports & Exercise, 50(8), 1649–1 RESULTS: In the OB group, the frequency of HR kinetics with mono-exponential, biexponential, and exponential+linear models was 2, 10, and 4, respectively, whereas in NW group was 2, 12, and 2, respectively, with no significant differences in frequency between groups (p = 0.65). Significant differences between NW and OB groups were found in baseline HR (p = 0.018) and time delay (p = 0.001). Significant correlations were observed in the OB group between baseline heart rate and LF (Rho = -0.51) and LF/HF (Rho = -0.46). In the other hand, in the NW group, significant correlations were observed between fundamental HR and LF (Rho = 0.42) and VLF (Rho = 0.47). CONCLUSION: NW and OB persons exhibit similar HR responses to constant load moderate exercise, and not all subjects exhibit the HR slow component. Parameters of heart rate variability are related differently with heart rate kinetics parameters in OB and NW groups. Further studies could focus on identifying factors that determine the type of heart rate response to moderate exercise intensity.
Read CV Hugo Aceituno PintoECSS Paris 2023: OP-PN32
INTRODUCTION: Cardiovascular disease (CVD) stands as a primary contributor to global mortality. Arterial stiffness has been established as an independent risk factor for both CVD and mortality. Peripheral pulse wave velocity (pPWV) serves as an indicator of arterial stiffness and represents a significant risk factor for CVD. Previous research has demonstrated an association between vitamin D deficiency and arterial stiffness (1). Prior study has indicated that high intensity interval training (HIIT) can effectively improve arterial stiffness (2). However, the impact of HIIT training on individuals with different levels of vitamin D remains unclear. The primary objective of this study was to compare different vitamin D status on vascular function following two weeks HIIT in healthy adults. METHODS: Forty-three adult males were divided into the 25(OH)D sufficient group (n=29, vitamin D≧50 nmol/L) and deficient group (n=14, vitamin D <50 nmol/L). The maximal graded exercise was performed using on upright bikes an incremental cycling test to exhaustion. The training intervention consisted of two weeks of high intensity cycling training, five days/week, consisting of 10 × 1 min bouts at 90% of HRpeak with 1 min rests. The pPWV and blood pressure (BP) were measured at baseline, on the mid-training, and post-training. The pPWV and BP variables were subjected to a two-way analysis of variance (ANOVA). Subsequent to identifying significant interaction and main effects, post hoc comparisons were conducted using t-test analysis. Changes in mean arterial pressure (MAP) and pPWV during HIIT were assessed using the area under the curve (AUC) method based on the trapezoidal rule, followed by a t-test on AUC values between groups. The accepted level of significance was set at p < 0.05. RESULTS: Baseline characteristics showed no significant differences, except for vitamin D concentrations. Both the vitamin D sufficient and deficient groups exhibited a significant reduction in pPWV (p < 0.05). The vitamin D sufficient group showed a significant lower systolic BP at post-HIIT compared with deficient group (116.17 ± 11.39 vs 120.25 ± 11.22 mmHg). The sufficient group demonstrated a significant reduction in systolic BP at post-HIIT compared to baseline (122.59 ± 13.65 vs 116.17 ± 11.39 mmHg). In addition, AUC for both pPWV and MAP in vitamin D sufficient group was significantly smaller than deficient group (p < 0.05). There were no significant changes in systolic BP between the baseline and post-HIIT training in the vitamin D deficient group (p > 0.05). CONCLUSION: In this study, we found that adults with 25(OH)D sufficiency have a better vascular function improvement after two weeks of HIIT. People with sufficient vitamin D status may experience better vascular vasodilation and blood pressure reduction during each high-intensity training session. 1. Chen, L. Y., et al. Nutrients, 14(15), 3074. (2022) 2. Hasegawa, N., et al. Med Sci Sports Exerc 50(6), 1177-1185. (2018)
Read CV Liang You ChenECSS Paris 2023: OP-PN32