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Scientific Programme

Physiology & Nutrition

CP-PN11 - Energy and muscle metabolism

Date: 04.07.2024, Time: 18:30 - 19:30, Lecture room: Forth

Description

Chair TBA

Chair

TBA
TBA
TBA

ECSS Paris 2023: CP-PN11

Speaker A Jack Eoin Rua ONeill

Speaker A

Jack Eoin Rua ONeill
University College Dublin, School of Public Health, Physiotherapy, and Sport Science
Ireland
"Effect of accustomed endurance exercise on next-day resting metabolic rate in male athletes"

INTRODUCTION: Best practice guidelines recommend avoiding physical activity for 12-48 hours before RMR testing [1], a challenge for athletes training daily. Recent findings suggest resistance but not aerobic exercise elevates RMR in non-athletes [2]. This study investigates the effect of accustomed exercise on next-day RMR in male endurance athletes, using a randomised crossover design, offering insights for RMR assessment in this population. METHODS: Thirteen male endurance athletes undertook rest and exercise conditions in random order one week apart. For the rest condition participants were instructed to perform no exercise for 24 hours before RMR measurement. For the exercise condition they were instructed to undertake a routine steady-state session rated 3-4 on the CR-10 scale [3] on the day prior to RMR measurement. Characteristics of exercise including heart rate were recorded. RMR was measured using a Q-NRG indirect calorimeter, with a within-subject CV of 2.4%±1.6% (range: 0.2%-6%) for day to day reliability based on unpublished data from our lab (n=30) measured following best practice guidelines. In the present study, if participants inter- day CV fell outside this range (>6%), their activities in the preceding 72 hours were further characterised for reasons that may explain a greater variability. Recovery markers were also assessed including blood urea and wellness questionnaire scores [4]. Paired t-tests and Wilcoxon tests compared differences between conditions, CVs assessed inter- day consistency, and Pearsons correlations tested associations between RMR and recovery markers. Significance was set at P<0.05. RESULTS: Exercise modalities included 5 undertaking indoor and 4 outdoor cycling, 3 outdoor running, and 1 indoor rowing, with mean (SD) session duration 01:51±01:11 (hh:mm), heart rate 128±16 bpm and RPE score 3.33±0.47. No significant differences were found in post-exercise vs rest RMR (1979±289 vs 1958±251 kcal/day, P=0.74), urea (42±6 vs 39±10 mg/dl, P=0.43), or RQ (0.77 vs 0.78, P=0.62). Wellness scores were lower post-exercise than rest (16.5 vs. 18.8, P=0.03); only sleep quality approached, but did not reach, significant difference (P=0.06). No correlations were observed between recovery markers and RMR changes. Inter-day CVs indicated consistency in RMR between days: 3.8%±3.4%. However, on an individual basis two participants had CVs >6%. Both adhered to guidelines on the day prior to measurement but undertook a high intensity session/competition approximately 48 hours prior. CONCLUSION: These findings suggest moderate intensity accustomed endurance exercise may be undertaken on the day prior to RMR measurement without altering results. However, practitioners may need to consider restriction of high intensity exercise in the 48 hours prior to testing. This warrants further study. [1] S. Fullmer et al. 2015 [2] K. MacKenzie-Shalders et al. 2020 [3] C. Foster et al. 2001 [4] B. D. McLean et al. 2010

Read CV Jack Eoin Rua ONeill

ECSS Paris 2023: CP-PN11

Speaker B Jarred Acton

Speaker B

Jarred Acton
Loughborough University, Sport, Exercise and Health Sciences
United Kingdom
"MITOCHONDRIAL RESPIRATORY FUNCTION IS NOT IMPAIRED FOLLOWING SEVERE-INTENSITY CYCLING EXERCISE IN HEALTHY MALES"

INTRODUCTION: Impaired mitochondrial respiratory function [increased uncoupled leak respiration through complex I (CIL) or lower coupled respiration through complexes I+II (CI+IIP)] following high-intensity exercise has been reported in some, but not all previous studies. Therefore, the purpose of the current study was to determine the effect of severe-intensity cycling exercise on mitochondrial respiratory function compared to resting values. METHODS: Thirteen recreationally active (V̇O2peak, 48.0 ± 6.6 ml/kg/min) male participants reported to the laboratory on three separate occasions. Initially, participants performed a 30 W/min linear ramp incremental cycle test until the limit of tolerance (Tlim), to determine the gas exchange threshold (GET) and V̇O2peak. On visit two, participants were familiarised to a constant-load cycling exercise test at a work-rate equivalent to the GET, plus 70% of the difference between V̇O2peak and GET (70%Δ), until Tlim. Time taken to reach Tlim was recorded to the nearest second and 80% of this time was calculated and termed 80%Tlim. On the final visit, muscle biopsies were taken from the m. vastus lateralis, at rest and following performance of the 70%Δ constant load exercise test to 80%Tlim. Mitochondrial respiratory variables in permeabilised muscle fibres were assessed using high-resolution respirometry. Specifically CIL, coupled respiration through complex I (CIP) and complexes I+II (CI+IIP), and noncoupled maximal electron transfer system capacity through complexes I+II (CI+IIE), complex II (CIIE) and complex IVE were determined. The following flux control ratios (FCRs) were subsequently calculated Leak control ratio (LCR; CIL/CI+IIE), phosphorylation control ratio (PCR; CI+IIP/CI+IIE), inverse respiratory control ratio (INV-RCR; CIL/CI+IIP), substrate control ratio (SCR; CIp/CI+IIP) and complex IV reserve control ratio (CIVres; CI+IIP/CIVE). All samples were analysed in quadruplicate and analysis order was counterbalanced. Citrate synthase activity was used as a validated surrogate of mitochondrial content. Paired T-tests were used to assess the difference between the mitochondrial respiratory variables at rest and post exercise. RESULTS: Mass-specific CIP¬ (12%), CI+IIP (9%) and CI+IIE (9%) respiration was greater post exercise compared to rest (all P =0.048). There were no differences between time points for CIL, CIIE and CIVE and the FCRs (P > 0.05). There were no differences in CS activity or in mitochondrial respiration parameters or FCRs between time-points when mass-specific respiration was corrected to CS activity (P > 0.05). CONCLUSION: Mitochondrial respiratory function was not impaired following acute severe-intensity cycling exercise to 80% of Tlim. These findings conflict with some previous research and could be explained by this study counterbalancing the order in which the resting and post-exercise biopsies were analysed, thus mitigating the potential carry over effect of chemical inhibitors.

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ECSS Paris 2023: CP-PN11

Speaker C Kevin Méndez

Speaker C

Kevin Méndez
University of Coruña, Galicia
Spain
"The effect of work and rest redistribution on different physiological and perceptual variables during three HIIT protocols. "

INTRODUCTION: During High Intensity Interval Training (HIIT), work and rest time could be modified to induce different metabolic, mechanical, and perceptual responses (Buchheit & Laursen, 2013). However, up to date, it was not investigated the effect of different work and rest distribution maintaining the same amount of workload and recovery time during a HIIT session. Therefore, the aim of the present study is to compare acute physiological (e.g. ventilatory), metabolic (e.g.: lactate), and perceptual (e.g.: RPE) responses during three HIIT protocols matched in volume and intensity but performed with different work and rest distribution. METHODS: Five males and five females (n=10, 27,4 ± 5,4 years, 52,3 ± 7,8 ml/kg/min, 184,9 ± 10,2 bpm, 4,8 ± 0,7 w/kg) underwent graded exercise testing to volitional exhaustion in a cycle ergometer to test they maximal aerobic power (Wmax). Then, they were required to complete three different HIIT training sessions that consisted of a total work time of 12 minutes at 80% of Wmax interposed with a total recovery time of 8 minutes at 25%of Wmax. These protocols have different configurations as described below: 1) 3 x 4 minutes bouts with 4 minutes recovery in between, 2) 6 x 2 minutes bouts with 1 minute and 36 seconds recovery in between; and 3) 12 x 1 minute bouts with 44 seconds in between. Ventilatory (VO2 Master 3230, British-Columbia, Canada), cardiovascular (Polar H10, Finlandia), metabolic (Lactate Pro-2, Arcray Inc) and perceptual (Borg CR-10 scale) response were recorded in each training session and analysed off-line. A one-way repeated measures ANOVA was performed to detect differences between all protocols performed. A statistical level of p < 0,05 was accepted. All data were presented as mean ± SD. RESULTS: All the variables analysed in the present study showed higher respiratory (ventilation (+14% and 22%) and tidal volume (+9% and +14%)), metabolic (Lactate, +28% and +91%), cardiovascular (heart rate, +5% and +8%) and perceptual (RPE (+7% and +22%) and leg pain (+2% and +19%)) demands during the protocol configured with larger intervals (4 min) compared to those configured with shorter intervals (2 and 1 min, respectively), despite the total workload and total rest time were matched. CONCLUSION: Shorter interval duration shows an attenuated ventilatory, cardiovascular, metabolic and perceptual responses compared with longer interval duration although the equalised volume and intensity resulting in same total workload. This results should be taken into account when prescribing HIIT to enhance performance.

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ECSS Paris 2023: CP-PN11