ECSS Paris 2023: CP-AP23
INTRODUCTION: Ramp-incremental (RI) cycling protocols may allow to determine the constant work rate (CWR) oxygen uptake (V̇O2)-Power Output (PO) relationship(1) and hence the full spectrum of exercise intensity prescription(2). Endurance performance variables like the Gas Exchange Threshold (GET), the Respiratory Compensation Point (RCP), the maximal V̇O2 (V̇O2peak) and the energy depleted above RCP (Wramp) can be derived from a Step-Ramp-Step (SRS) protocol(2,3). However, reliability of these variables determined with the SRS protocol has not been reported and the agreement of the corrected PO at RCP (PORCP) and Wramp with gold-standards is equivocal(2,4,5). Also, recent research has focused on moderately active populations (Tier 0 and 1(6)) and studies with fitter individuals are lacking. Therefore, the goals of this study were to: 1) study the reliability of endurance performance variables from a modified SRS protocol in trained triathletes and 2) evaluate the agreement between PORCP and Wramp derived from the SRS protocols with the critical power (CP) and the quantity of energy depleted above CP (W) computed from 4 CWR exercise trials to failure. METHODS: Twelve trained triathletes (Tier 2(6), 31 ± 6 yr, 72.2 ± 4.3 kg, V̇O2peak = 67.9 mL.min-1.kg-1) attended the laboratory 8 times to conduct a SRS protocol (visit 1), multiple CWR trials to failure (visits 2-5), a modified SRS protocol (twice, visits 6 and 7) and a CWR into the heavy-intensity domain (visit 8). PORCP was corrected similarly to recent studies(2,3) and W’ramp>CP or W’ramp>RCP were computed as the energy depleted above CP and PORCP respectively. RESULTS: Coefficients of variation for V̇O2 variables were within a range of 2.1 to 3.7 % (CI95% : [1.5, 3.6] to [2.6, 6.3] %), for corrected PO at GET and RCP 3.0 % and 2.9 % (CI95% : [2.1, 5.1] % and [2.0, 5.9] %) and for Wramp>CP and Wramp>RCP 11.3 % and 11.6 % (CI95% : [8.0, 19.3] % and [8.2, 19.9] %). CP was higher than PORCP (bias 17 to 20 W, bias CI95% : [4, 29] to [6, 35] W, CCC = 0.52 to 0.67) and W’ was higher than Wramp>CP (bias 1.5 to 6.2 kJ, bias CI95% : [-1.2, 4.3] to [4.2, 8.1] kJ, CCC = 0.48 to 0.74). Wramp>CP derived from the second modified SRS was higher than Wramp>CP derived from the SRS (+4.6 kJ, CI95% : [1, 8.2] kJ). CONCLUSION: In trained triathletes, the modified SRS protocol provides good test-retest reliability for GET, RCP and V̇O2peak. Using the existing corrections strategies, CP was higher than PORCP and W’ was higher than Wramp>CP. Although the variability associated with W’ramp>CP is important, the modified SRS protocol may provide closer estimates for W’ramp>CP than the classical SRS protocol. 1 : Stuer et al., MSSE, 2025. 2 : Iannetta et al., MSSE, 2023. 3 : Iannetta et al., MSSE, 2020. 4 : Caen et al., MSSE, 2023. 5 : Micheli et al., APNM, 2024. 6. McKay et al., IJSPP, 2022.
Read CV Quentin RousseauECSS Paris 2023: CP-AP23
INTRODUCTION: The concept of optimal cadence in cycling performance can be examined from both a metabolic and a biomechanical standpoint. Metabolic Optimal Cadence (MOC) refers to the cadence that minimizes metabolic demands, such as oxygen consumption (VO2), thereby improving endurance performance. Biomechanical Optimal Cadence (BOC) can be assessed as improved neuromuscular efficiency measured via electromyograph (EMG), where total muscle excitation is minimized. The primary objective of this study was to investigate the possibility of predicting MOC from BOC. METHODS: Each participant visited the lab twice. Visit 1 included a graded exercise test to determine maximal O2 uptake (VO2max) and the first ventilatory threshold (VT1). During visit 2, participants completed 35 minutes of cycling at a constant power output equivalent to 110% of VT1, where every five minutes cadence (60, 70, 80, 90, 100, 110, 120 rpm) was randomly changed. Participants were equipped with 13 EMG sensors on the quadriceps and hamstrings muscles, tibialis anterior, gastrocnemius, gluteus max and multifidi of the right side of the body. Additionally, they were connected to a metabolic system to allow continuous monitoring of metabolic variables. One minimum point was extracted from fitted parabolic curves for VO2 (i.e., MOC) and for muscles excitation and co-contraction (i.e., BOC) for each participant. Model II linear regression and Bland-Altman plots were performed to assess the relationship between MOC and BOC. RESULTS: Fifteen highly trained triathletes and cyclists participated in this study (14 males; mean±SD.; age: 24±5 years, height: 1.76±0.05 m, body mass: 66.8±5.1 kg, VO2max: 65.9±8.3 mL/kg/min, training volume: 18±7 hours per week). They came from the fields of triathlon, road, cross country and track cycling (n=9,3,2,1 respectively). The preferred cadence reported by the participants was 88±9 rpm. As analysed from VO2 data, MOC was 60±14 rpm. Conversely, EMGs provided greater BOC values (95±13 rpm for KE, 84±14 rpm for KF). The mean BOC leading to minimal KE-KF co-contraction was 91±7 rpm. For plantar flexors and for ankle co-contraction, BOC values were respectively 85±18 rpm 87±18 rpm. The relationship between MOC and KE showed fixed bias (35 rpm) with confidence interval (CI) for the intercept between 1.8-64.6 rpm. The relationship between MOC and KE-KF co-contraction showed both proportional bias (CI intercept: 38.2-73.7 rpm) and fixed bias (CI slope: 0.3-0.9). According to the Bland-Altman analysis, difference MOC and BOC were highly variable (CI: 1–71 rpm). CONCLUSION: BOC values were on average greater than MOC values. Notwithstanding the fixed bias observed for KE, suggesting MOC may be predicted from KE EMGs (i.e., MOC = BOC – 35 rpm), the somewhat high variability observed in the Bland-Altman plots between MOC and BOC KE warrants further investigation.
Read CV Evyatar OhayonECSS Paris 2023: CP-AP23
INTRODUCTION: Blood flow restriction (BFR) allows exercise at lower absolute intensity yet, showing similar or greater results compared with traditional training in non-trained individuals. However, since the effects in well-trained competitive athletes are unclear, the current study aims to compare the effect of an effort matched short HIIT microcycle performed with or without BFR, on indicators of endurance performance in well-trained cyclists. METHODS: 17 well-trained cyclists (aged 31 ± 9 years, maximal oxygen uptake (VO2max: 67±6mL/min/kg) were randomised in two groups performing a microcycle of five HIIT sessions (6 x 5 min intervals with 2.5 min of recovery) with (BFR group) or without (HIIT group) a cuff over the thighs occluding the limbs. An exercise cycling test was used to assess VO2max, mean power output at 4 mmoL/L blood lactate (LT4), and mean power output during 5-min maximal cycling (MPO5) and the percentage of maximal oxygen consumption used at LT4 (%VO2max @LT4). Haemoglobin mass (HB) and blood volume (BV) were measured by CO rebreathing. Moreover, muscle biopsies on the vastus lateralis were used to evaluate muscle cross-sectional area (CSA), capillaries around fibre area (CAFA), citrate synthase (CS), Hydroxyacyl-Coenzyme A dehydrogenase (HADH), cytochrome c oxidase 4 (COX4), and αβ-Crystallin (CRYAB) RESULTS: The BFR group trained at a lower power output compared to the HIIT group (177±3 W vs 307±8 W, respectively, p<0.01), but with no group differences in heart rate or rate of perceived exertion. Both groups significantly improved MPO5, with no significant changes in LT4, VO2max, HB and BV. However, only HIIT improved significantly %VO2max@LT4. Moreover, HIIT showed a significant reduction in CSA for type 2 muscle fibres compared with BFR whereas no significant changes were found in the other biomolecular indexes. CONCLUSION: BFR applied during a 6-day microcycle provides similar but not greater physiological adaptations than traditional HIIT linked to exercise performance in well-trained cyclists. BFR achieved similar performance gains as the HIIT group with similar perceived effort and heart rate, but with 40% lower average power output during the training sessions. Moreover, despite HIIT having a significant reduction in CSA type 2 compared to BFR, no group differences were observed in capillarisation, CS, HADH, COX4, αβ-Crystalline (CRYAB) content. These results might be important for athletes who are seeking to promote positive adaptation in a relatively short period of time, or athletes who are recovering from injuries and want to obtain similar adaptation as HIIT with reduced mechanical stress. Future studies will be needed to ascertain if these adaptations can be maximized following consecutive intensified blocks and be of benefit to elite athletes with higher cardiorespiratory fitness and performance.
Read CV Fabio ZambolinECSS Paris 2023: CP-AP23