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Scientific Programme

Physiology & Nutrition

OP-PN01 - Nutrition I

Date: 02.07.2024, Time: 13:30 - 14:45, Lecture room: Gala

Description

Chair TBA

Chair

TBA
TBA
TBA

ECSS Paris 2023: OP-PN01

Speaker A Cas Fuchs

Speaker A

Cas Fuchs
Maastricht University, Department of Human Biology
Netherlands
"Carbohydrate feeding replenishes liver glycogen content well within 6 hours of post-exercise recovery in well-trained cyclists. "

INTRODUCTION: Both liver and muscle glycogen contribute substantially to energy requirements during prolonged moderate- to high-intensity exercise. Carbohydrate intake after exercise is essential to replenish both liver and muscle glycogen stores. Consuming ample carbohydrates has shown to replenish muscle glycogen concentrations within 24 h following exhaustive cycling. Yet, the time required to replenish liver glycogen after exercise in vivo in humans remains to be determined. METHODS: Twelve well-trained male cyclists (age: 25±5 y; VO2peak: 67±5 mL/kg/min; Wmax: 5.8±0.7 W/kg) completed two test days in a randomized cross-over fashion. On both test days, liver and muscle glycogen values were assessed before and immediately after a glycogen depleting exercise session on a cycle ergometer. This was followed by a 12-h recovery period where participants remained fasted (CON) or consumed 10 g carbohydrates per kg body mass (BM) in the form of sucrose containing beverages and carbohydrate-rich meals (CHO). Liver and muscle glycogen levels were measured again at 6 and 12 hours into recovery. We applied 13C-Magnetic Resonance Spectroscopy (13C-MRS) to quantify liver and muscle glycogen concentrations and Magnetic Resonance Imaging to measure liver and muscle volume. In addition, muscle biopsies were collected to determine muscle glycogen concentrations. A two-factor (time*treatment) repeated-measures ANOVA was performed, with significant findings being further investigated through Bonferroni post hoc tests. Muscle and liver glycogen data are expressed as percentage signal intensity from 13C-MRS, with pre-exercise values set as 100% with the other values being expressed as relative changes from pre-exercise values. Data are expressed as means ± SD. RESULTS: Exercise significantly reduced liver glycogen to 60±12% in CON and 64±16% in CHO, and muscle glycogen to 35±8% of pre-exercise values in both CON and CHO (all P<0.001), with no significant differences between the CON and CHO day (liver: P=0.488 and muscle: P=0.803). Without carbohydrate intake (CON), liver glycogen levels further declined (12 h: 46±11% of pre-exercise values; P=0.002), while muscle glycogen levels remained unchanged (12 h: 38±9% of pre-exercise values) compared to post-exercise values (P=0.596). Following carbohydrate intake (CHO), liver glycogen levels increased beyond pre-exercise values well within 6 h (145±24% of pre-exercise values; P<0.001) with no further increase at 12 h (160±29% of pre-exercise values; P=0.111). Despite ample carbohydrate intake, muscle glycogen levels remained below pre-exercise values after 12 hours of post-exercise recovery (71±12% of pre-exercise values; P<0.001). CONCLUSION: Carbohydrate ingestion (1.2 g/kg BM/h) during recovery from exhaustive exercise rapidly replenishes liver glycogen content well within 6 hours. Ingesting 10 g of carbohydrate per kg BM does not fully replenish muscle glycogen stores to pre-exercise values within a 12-hour recovery period.

Read CV Cas Fuchs

ECSS Paris 2023: OP-PN01

Speaker B Christopher  Nulty

Speaker B

Christopher Nulty
South East Technological University, School of Sport and Exercise Sciences; Health & Sport Sciences; Institute of Sport, Exercise & Health
Ireland
"Hydrolysed collagen supplementation augments patellar tendon hypertrophy and rate of force development following eight weeks’ resistance training in female Masters field hockey athletes"

INTRODUCTION: Despite a high prevalence of lower-limb soft tissue injuries in female Masters field hockey athletes [1], effective exercise and nutrition strategies to mitigate injury risk and enhance performance in this population are unknown. In young female athletes, however, body weight resistance exercise (RE) training with 30g hydrolysed collagen (HC) supplementation enhances patellar tendon (PT) stiffness (which may reduce injury risk and increase performance), although PT cross-sectional area (CSA) remained unaffected [2]. Higher intensity, eccentric RE may cause tendon hypertrophy, thus enabling a greater efficiency of force transfer from muscle to bone, thereby increasing peak rate of force development (pRFD) and athletic performance. The aim of this study was therefore to investigate the effect of HC supplementation combined with high-intensity, eccentric RE on PT CSA, muscle size, strength, power, speed and pRFD in female Masters athletes. METHODS: Twenty-two international female premenopausal Masters field hockey athletes were randomly assigned to collagen (COL, n=10, 40±4 years, 69±5 kg) and placebo (PLA, n=12, 38±3 years, 69±9 kg) cohorts in a double-blind design, and completed a weekly supervised high-intensity flywheel squat RE session and two home-based lower-limb eccentric bodyweight RE sessions for eight weeks. Prior to each RE session, participants ingested either 30g HC (COL) or 30g maltodextrin (PLA), together with 500mg Vitamin C. Before and after the intervention, maximum voluntary force (MVF) and pRFD were assessed during an isometric mid-thigh pull using force plates. Vastus lateralis (VL) muscle thickness (MT) and PT CSA were measured with ultrasonography. Countermovement jump (CMJ) height and 20 m sprint speed were evaluated using force plates and timing gates, respectively. RESULTS: MVF increased from 892±366 to 1,011±420 N (P=0.020), VL MT from 21±3 to 22±3 mm (P=0.015), and sprint speed from 5.7±0.4 to 5.8±0.4 m∙s-1 (P=0.011), with no group×time interactions (P>0.05), while CMJ height did not change (P=0.238). PT CSA increased in both groups (P<0.001) but COL (116±12 to 121±13 mm2) increased more than PLA (109±22 to 111±22 mm2, P=0.014). Similarly, pRFD increased post-training (P=0.002) but to a greater extent in COL (7.9±1.3 to 10.1±2.4 kN∙s-1) than in PLA (8.5±3.4 to 9.1±3.4 kN∙s-1, P=0.039). CONCLUSION: Eight weeks’ eccentric RE with 30g HC supplementation augments the gains in PT CSA and pRFD in international female Masters field hockey athletes. The greater PT hypertrophy in COL may have influenced the larger increase in pRFD in COL by augmenting RE-induced gains in PT stiffness. REFERENCES: 1. Croteau K. et al. 2022. Injuries in Masters Field Hockey Players Competing in the 2018 World Cup: Comparisons of Prevalence, Location, and Type by Age, Sex, and Field Hockey Experience. Int J Athl Ther Train.27(4):188-192. 2. Lee J. et al. 2023. Collagen supplementation augments changes in patellar tendon properties in female soccer players. Front Physiol.14:60.

Read CV Christopher Nulty

ECSS Paris 2023: OP-PN01

Speaker C Jiaqi ZHANG

Speaker C

Jiaqi ZHANG
The Chinese University of Hong Kong, Department of Sports Science & Physical Education
Hong Kong
"Acute Effects of Various Doses of Nitrate-Rich Beetroot Juice on High-Intensity Interval Cycling Responses in Women: A Randomized, Double-Blinded, Placebo-Controlled, Crossover Trial"

INTRODUCTION: Nitric oxide (NO) plays a critical role in improving mitochondrial efficiency and muscle contractile efficiency during exercise and can be exogenously increased via nitrate supplementation. While numerous studies have investigated the effects of nitrate supplementation on exercise performance, most literature has focused on endurance-based exercise protocols. Meanwhile, the optimal dose of nitrate supplementation to maximize performance benefits during high-intensity interval exercise remains unclear, as previous studies have utilized a wide range of nitrate doses and predominantly recruited male participants, overlooking potential sex differences in responses to nitrate supplementation. Therefore, this study aimed to investigate the acute effects of various doses of nitrate-rich beetroot juice on the responses to high-intensity interval cycling in women. METHODS: A double-blinded, randomized, placebo-controlled, crossover trial was conducted with 13 recreationally active young women (age = 23 ± 2 years). All participants performed interval exercise (8 × 1-min bouts of cycling at 85 % of peak power output [PPO] interspersed with 1-min active recovery at 20% of PPO) 2.5 h after consumption of the randomly assigned beetroot juice containing 0 mmol (placebo control group [PLA]), 6.45 mmol (single-dose group [SIN]), or 12.9 mmol (double-dose group [DOU]) nitrates. The heart rate (HR), blood pressure, blood lactate, blood glucose, oxygen saturation, rating of perceived exertion (RPE), and emotional arousal were assessed. All data collected during the interval exercises were analyzed using a two-way (treatment × time) repeated-measures ANOVA to explore the effect of interventions (PLA, SIN, and DOU) over time on the magnitude of each dependent variable. Statistical significance was set at p < 0.05. RESULTS: Nitrate supplementation significantly altered the HR and RPE responses across the three trials. The mean HR was lower in the SIN and DOU groups than in the PLA group during both work intervals (F[1.90, 195.78] = 7.06, p = .001, η_p^2 = .064) and recovery periods (F[2, 180] = 9.89, p < .001, η_p^2 = .099), as well as across the overall protocol (F[1.93, 374.47] = 16.90, p < .001, η_p^2 = .080). The mean RPE was lower in the SIN and DOU groups than in the PLA group during recovery periods (F[2, 180] = 10.39, p < .001, η_p^2 = .104) and across the overall protocol (F[2, 388] = 11.96, p < .001, η_p^2 = .058). However, there was no significant difference in either HR or RPE between SIN and DOU on any endpoint. CONCLUSION: Acute nitrate ingestion led to significant decreases in the mean HR and RPE during high-intensity interval cycling, but no additional benefit was observed with higher nitrate content. These findings may assist practitioners in implementing more effective nitrate supplementation strategies to enhance performance and adaptation during interval exercise.

Read CV Jiaqi ZHANG

ECSS Paris 2023: OP-PN01