ECSS Paris 2023: OP-PN19
INTRODUCTION: Maximal oxygen uptake (VO₂max) often increases in response to endurance training, but the magnitude of adaptation varies between individuals and appears to differ across developmental stages. A widespread view is that VO2max trainability is considerably lower in children than in adults. However, training load is usually not controlled and potential mechanisms for such a phenomenon remain unclear. Therefore, we aimed to quantify VO₂max trainability across development while accounting for training load in a systematic manner (preregistration-DOI: 10.17605/OSF.IO/V8UHT). METHODS: Following PRISMA-RR guidelines, we conducted a rapid systematic review with meta-analysis using MEDLINE. Peer-reviewed randomized controlled trials including healthy, normal-weight participants aged 6-40 years were eligible if relative VO₂max was directly measured by spiroergometry before and after a structured endurance training intervention. Standardized mean differences (Hedges’ g) of pre–post changes between intervention and control groups were computed. A random-effects meta-regression was performed with chronological age and training load (derived from reported intensity and duration using TRIMP) as moderators. Both linear and non-linear age effects were explored to identify the most appropriate model fit. RESULTS: From 4’669 screened records, 82 studies were included, yielding 91 intervention-control effect sizes. The best model fit was provided by a random-effects meta-regression including training load and a non-linear age term (natural spline, df = 3). Training load was a significant positive predictor of relative VO₂max adaptations (β = 0.124, SE = 0.034, p = 0.0002, per 1000 TRIMP). In contrast, the age-response relationship was shallow, with only weak evidence for non-linearity, indicating similar trainability from childhood to young adulthood. CONCLUSION: Training load appears to be the most important determinant of VO₂max adaptations across development, whereas age shows only a weak non-linear association. These findings challenge the prevailing view of markedly limited VO₂max trainability in youth and highlight the importance of precise quantification of training load when interpreting training responses. Future analyses will examine the influence of body size using allometric scaling and explore potential differences in endurance performance outcomes. Furthermore, we suggest that maturation status and investigation of dose-response relationships should be considered in future research.
Read CV Romina LedergerberECSS Paris 2023: OP-PN19
INTRODUCTION: Maximal oxygen consumption (VO₂max) shows a well established age related decline mainly driven by central cardiovascular limitations (1). In contrast, the behaviour of ventilatory thresholds (VT) is less clear, with studies reporting inconsistent age related patterns and sex specific differences. These discrepancies are partly explained by the different methods used to estimate and determine VT (2,3). In addition, the distinct peripheral mechanisms influencing VT, highlight the need for large scale analyses that clarifies their lifespan trajectory. Therefore, the aim of this study was to model age related changes in VT throughout life, using both classical linear regression and newer approaches such as machine learning. METHODS: The cross‑sectional dataset consisted of 3,538 individuals (18–83 years; 79.6% males) who performed a ramp incremental test to volitional exhaustion on either a treadmill or a cycle-ergometer. Oxygen consumption relative to body weight at the VT and VO₂max were determined using standard ventilatory and gas‑exchange criteria (4). Age‑related associations were examined using linear and polynomial regression models complemented by XGBoost to detect complex or non‑linear relationships. RESULTS: Both VT showed a clear non‑linear decline with advancing age, with steeper reductions observed in males. VT1 declined between approximately −1.1 and −1.7 mL·kg⁻¹·min⁻¹ per decade depending on sex, while VT2 showed an even larger reduction ranging from −1.3 to −2.6 mL·kg⁻¹·min⁻¹ per decade. VO₂max also decreased substantially up to −3 mL·kg⁻¹·min⁻¹ per decade (in males). Conversely, both thresholds expressed as %VO₂max remained remarkably stable across the lifespan, displaying near‑zero slope values regardless of age, sex or ergometer. These patterns were consistent across all modeling approaches, with little to none differences between lineal regression and XGBoost. CONCLUSION: Results indicate a preserved proportional metabolic regulation despite substantial reductions in absolute aerobic capacity. Our findings also highlight the strong relationship between the proportional decrease in consumption at VT and the decrease in VO2max. In addition, our large sample size also allows us to provide a reference for how much oxygen consumption is expected to decrease at the VT over the course of a lifetime. This also underscores the importance of not neglecting the training of both VT and using them as an effective methodology for prescribing training throughout the entire life span. REFERENCES: 1. Letnes J.M. et al, 2023, DOI: 10.1016/j.ijcrp.2023.200171 2. Anselmi F. et al, 2021, DOI: 10.1111/sms.14007 3. Martini A.D. et al, 2022, DOI: 10.3390/ijerph19073962 4. Rabadán M. et al, 2011, DOI: 10.1080/02640414.2011.571271
Read CV Alberto Armero-SotilloECSS Paris 2023: OP-PN19
INTRODUCTION: Most evidence describing endurance-training adaptations derives from cross-sectional comparisons (athletes vs. non-athletes) or short-term interventions (i.e. 4-12wk). Consequently, longitudinal responses to prolonged ultra-endurance training in exercise-naïve individuals remain poorly characterized, and it is unclear whether training elicits primarily improvements in maximal aerobic power (VO₂max) and/or submaximal metabolic adaptations that shift thresholds and enhance exercise sustainability. Therefore, we aimed to quantify changes in VO₂max and key determinants of endurance performance following 12 months of ultra-endurance training in exercise-naïve adults. METHODS: Forty-one exercise-naïve adults (21F:20M) enrolled in a 12-month individualized, progressive ultra-endurance training program; 31 participants completed testing at baseline (BL), 3, 6, and 12 months. Weekly training volume progressed from ~3h to ~17 h·wk⁻¹. VO₂max was determined during a graded cycling exercise test, from which power at the second ventilatory threshold (VT2) was also derived. Endurance performance was assessed as time-to-exhaustion during a constant-load cycling test (CLT) performed at 115% of BL VT2 power. Exercise sustainability was evaluated using time completed in the CLT (capped at 1800 s), blood lactate, heart rate (HR), and ratings of perceived exertion (RPE) sampled at 10-min intervals and at end-of-test. RESULTS: VO₂max increased from 38.4±7.3 at BL to 40.5±6.1 and 41.9±6.1 mL·kg⁻¹·min⁻¹ at 3 and 6 months, respectively (both p<0.001), no further improvement occurred at 12 months (42.2±7.0 mL·kg⁻¹·min⁻¹, p>0.05, +11±11% vs. BL). Time-to-exhaustion increased from 1210±539 s at BL to 1629±317 and 1759±150 s at 3 and 6 months, respectively (both p<0.026), with no further improvement at 12 months (1730±271 s, p>0.05, +76±77% vs. BL). Power at VT2 increased from 157±35 W at baseline to 190±43 W at 12 months (p<0.001, 22±18%), and peak blood lactate during the CLT decreased from 9.0±2.5 mmol·L⁻¹ at baseline to 4.6±1.9 at 12 months (p<0.001, -46±26%), accompanied by reductions in HRmax (180±14 to 164±15 bpm, p<0.001, -9±7%,) and RPE (7.2±1.6 to 4.7±1.5, p<0.001, -29±35%). CONCLUSION: Twelve months of ultra endurance training in exercise-naïve adults produced modest–albeit meaningful–improvements in VO₂max (+11%), whereas endurance performance increased markedly (+76%). The ~7-fold larger relative improvement in performance compared with VO₂max demonstrates that long-term endurance adaptations in exercise-naïve individuals training for an ultra-endurance event manifest predominantly as changes in the ability to sustain higher power outputs for longer, rather than marked increases in maximal O2 uptake. As most ultra-endurance training is done predominantly in training zones below VT2, it is understandable why there is a limited effect on VO2max despite substantial improvements in exercise tolerance, which are likely through specific cardiovascular and metabolic adaptations.
Read CV Liam StewartECSS Paris 2023: OP-PN19