ECSS Paris 2023: OP-PN29
INTRODUCTION: Endurance performance can be predicted by maximal oxygen uptake (V̇O2max), its fractional utilisation at lactate threshold (FULT), and exercise economy (1). These variables are used to estimate speed or power at lactate threshold (LT) and lactate turnpoint (LTP), which serve as performance proxies (1, 2). This study examined the relationships between these variables in a large cohort of runners and cyclists and quantified their relative contributions to performance prediction. METHODS: 495 runners (105 females) and 393 cyclists (42 females) completed incremental exercise tests to determine V̇O2max (running [R]: 56 ± 9 mL/kg/min, 3.94 ± 0.75 L/min; cycling [C]: 52 ± 10 mL/kg/min, 3.99 ± 0.66 L/min), economy (R: 220 ± 18 mL/kg/km; C: 14.7 ± 1.5 mL/min/W), FULT (R: 78 ± 5%; C: 70 ± 6%), FULTP (R: 88 ± 6%; C: 84 ± 6%), and speed or power at LT (R: 12.0 ± 2.2 km/h; C: 190 ± 39 W) and LTP (R: 13.9 ± 2.4 km/h; C: 240 ± 45 W). The test consisted of 4-min stages with increments of 0.5-1.0 km/h (R) or 10-30 W (C) depending on participant’s training background, followed by 15-20 min rest and a ramp test lasting 8-12 min. LT and LTP were defined as the first rise in blood lactate concentration (B[La-]) from baseline (+0.5 mmol/L) and as a rapid and sustained increase in B[La-] (+1.5 mmol/L) between two subsequent stages, respectively. Multiple correlations were assessed using linear models, with P-values corrected for multiple testing using the Holm-Bonferroni procedure. Multiple linear regression models were used to estimate the contribution of physiological determinants to performance proxies. Significance was set as P ≤ 0.05. RESULTS: Speed or power at LT and LTP correlated strongly and positively with V̇O2max (R² = 0.65-0.77; P<0.001), and inversely with economy (R² = 0.24-0.26; P < 0.001). In contrast, smaller relationships were observed with FULT (R² ≤ 0.04; P = 0.01-0.05) and FULTP (R² ≤ 0.01; P = 0.01-0.09). Regression models estimating LT and LTP from physiological determinants showed very strong agreement with measured performance proxies (LT: R² = 0.98-0.99, LTP: R² = 0.94-0.97; P < 0.001), indicating high consistency in their relative contribution to performance proxies. V̇O2max contributed most to performance proxies in both running (72-76%) and cycling (65-73%) followed by exercise economy (R: 20-22%, C: 21-24%), with marginal but significant contributions from FULT or FULTP (R: 4-6%, C: 6-11%). Similar results were found between sexes. CONCLUSION: These results are the first to indicate that, across a large and heterogeneous cohort of runners and cyclists, and between sexes, V̇O2max and economy collectively predict ~95% of speed or power at LT and LTP, and by extension endurance performance. Conversely, FULT or FULTP showed limited value in explaining between-athlete performance differences, confirming recent cross-sectional findings (3). 1. Joyner, 1991, J. Appl. Physiol. 2. Jones et al., 2021, J. Appl. Physiol. 3. Johansen et al., 2025, Int J Sports Physiol Perform
Read CV Loïs MouginECSS Paris 2023: OP-PN29
INTRODUCTION: Eccentric cycling (EC) is a novel approach for training and evaluating cardiometabolic and muscular function. Body position in cycling (recumbent, RC vs. upright, UP) may influence central and peripheral hemodynamic responses, due to differences in blood distribution, venous return, and muscle pump activity. Previous studies suggest cardiac output (CO) may be higher in RC at moderate intensities, with differences decreasing at higher intensities. Posture may affect central measures such as CO stroke volume (SV) and heart rate (HR), as well as peripheral factors (systemic vascular resistance (SVR) and left cardiac work index (LCWi)). However, limited evidence directly compares these responses between RC and UP positions during incremental EC. This study examined the effects of posture on CO, SV, SVR, and LCWi in healthy young adults. METHODS: After familiarisations, 49 participants (10F; 39M; 24±1 years; 70.9±11.1 kg; 1.76±0.09 m) completed two randomized incremental EC tests to voluntary exhaustion (starting from 100W for M and 50W for F + 25W·min⁻¹ at 65±5 rpm) in RC and UP position, separated by >14 days. CO, SV, HR, SVR and LCWi were continuously assessed using non-invasive impedance hemodynamic monitor. Data were analyzed using linear mixed-effects models with position and time as fixed factors and participant as a random effect. RESULTS: In both positions, comparing 20% to 80% of relative intensity, CO, SV, HR, and LCWi increased (CO: 41 and 44%; SV: 6 and 9%, HR: 32 and 31%, LCWi: 38 and 44%), while SVR decreased (28 and 24%) in RC and UP positions. Across all intensities, RC elicited higher CO (9-12-6-7%), SV (19-18-13-15%), and LCWi (8-11-7-4%) compared with UP, accompanied by lower HR (8-6-6-7%) and SVR (17-18-26-22%), at 20-40-60-80% of iso-relative load. Linear mixed-effects analysis confirmed main effect of intensity for all parameters (all p <0.001). A significant main effect of position was also observed (p<0.001), with the UP position showing lower CO (β = −0.8±0.1), SV (β = −14.0±0.7), and LCWi (β = −0.59±0.10), but higher HR (β = +13.0±0.6) and SVR (β = +210±47) compared with RC. CONCLUSION: Riding position significantly modulates central and peripheral cardiovascular responses during incremental EC across iso-relative intensities. The RC consistently elicited higher CO and SV, alongside lower HR and SVR, compared with the UP. These differences were maintained across the entire intensity range, indicating a stable postural effect rather than an intensity-specific divergence. These results support the notion that body position influences the balance between cardiac preload and afterload, highlighting the importance of considering posture and hemodynamic responses in evaluating, training and rehabilitation programs. Training posture should be tailored to individual cardiovascular and functional needs.
Read CV Laura GhiottoECSS Paris 2023: OP-PN29
INTRODUCTION: Horizontal deceleration (DEC) is an eccentric-based locomotor skill underpinning all changes of velocity. While eccentric exercise is associated with transient endothelial dysfunction [1], the effects of DEC intensity during repeated-sprint ability (RSA) exercise on vascular responsiveness have not yet been explored. Therefore, this study aimed to investigate the effects of different DEC intensities during an overground RSA protocol on vastus lateralis microvascular responses and oxidative capacity. METHODS: Twelve participants (25±3.5 yrs) randomly performed a running RSA protocol [3 sets of 8 × 20 m; 20-s passive recovery between sprints, 5-min rest between sets] with i) self-selected DEC post-sprint (DECfree), (ii) moderate enforced DEC (DEC10; 10-m braking distance post-sprint), and (iii) intense enforced DEC (DEC5; 5-m braking distance post-sprint). DEC performances were assessed using a radar gun. Vastus lateralis oxygenation kinetics was measured using near-infrared spectroscopy (NIRS) via the tissue saturation index (TSI). A supine vascular occlusion test (VOT) was performed before the RSA protocol to assess microvascular reactivity from TSI de- and re-saturation slopes. Muscle oxidative capacity was determined immediately post-exercise using repeated arterial occlusions. TSI desaturation slopes versus time curves during occlusions, reflecting the rate of post-exercise recovery of muscle oxygen consumption, were calculated using linear regression and subsequently fitted with a mono-exponential function to derive the recovery rate constant (k) [2]. RESULTS: Mean DEC was significantly larger in DEC5 (-3.57±0.32 m/s2) than DEC10 (-2.52±0.37 m/s2, p<0.001) and DECfree (-1.82±0.30 m/s2, p<0.001), and lower in DEC10 than DECfree (p<0.001). Baseline TSI was similar across conditions (DECfree=58±4 %, DEC10=59±6 %, DEC5=58±6 %; p=0.586). No condition effect was observed for NIRS-VOT-derived microvascular reactivity, with comparable TSI desaturation rate (DECfree=-0.10±0.04 %/s, DEC10=-0.10±0.05 %/s, DEC5=-0.11±0.08 %/s; p=0.720) and TSI reperfusion rate (DECfree=0.55±0.33 %/s, DEC10=0.67±0.30 %/s, DEC5=0.62±0.55 %/s; p=0.760). Similarly, muscle oxidative capacity also did not differ between conditions, as reflected by comparable k (DECfree=2.77±0.82 1/min, DEC10=2.52±0.91 1/min, DEC5=2.09±0.47 1/min; p=0.095). CONCLUSION: Microvascular reactivity assessed using a supine vascular occlusion test was comparable across conditions, with relatively low values likely related to reduced shear stress associated with body position. Despite markedly different deceleration intensities during repeated-sprint exercise, post-exercise muscle oxidative recovery kinetics were preserved. These findings suggest that acute eccentric demand imposed by deceleration do not compromise endothelial-dependent vascular control or oxygen delivery-utilization coupling at the microvascular level. [1] Larsen, Physiol Rep, 2019 [2] Adami & Rossiter, J Appl Physiol, 2018
Read CV Johan GarciaECSS Paris 2023: OP-PN29