Carbohydrate ingestion during prolonged exercise blunts the reduction in power output at the moderate-to-heavy intensity transition.

Purpose: To determine the effect of carbohydrate ingestion during prolonged exercise on durability of the moderate-to-heavy-intensity transition and severe-intensity performance.

Methods: Twelve trained cyclists and triathletes (10 males, 2 females; peak, 59 ± 5 mL kg min; training volume, 14 ± 5 h week) performed an incremental test and 5-min time trial (TT) without prior exercise (PRE), and after 150 min of moderate-intensity cycling, with (POST) and without (POST) carbohydrate ingestion.

Results: Power output at the first ventilatory threshold (VT) was lower in POST (225 ± 36 W, ∆ -3 ± 2%, P = 0.

The Training Intensity Distribution of Marathon Runners Across Performance Levels.

Background: The training characteristics and training intensity distribution (TID) of elite athletes have been extensively studied, but a comprehensive analysis of the TID across runners from different performance levels is lacking.

Methods: Training sessions from the 16 weeks preceding 151,813 marathons completed by 119,452 runners were analysed. The TID was quantified using a three-zone approach (Z1, Z2 and Z3), where critical speed defined the boundary between Z2 and Z3, and the transition between Z1 and Z2 was assumed to occur at 82.

A Novel Method to Predict Carbohydrate and Energy Expenditure During Endurance Exercise Using Measures of Training Load.

Background: Sports nutrition guidelines recommend carbohydrate (CHO) intake be individualized to the athlete and modulated according to changes in training load. However, there are limited methods to assess CHO utilization during training sessions.

Objectives: We aimed to (1) quantify bivariate relationships between both CHO and overall energy expenditure (EE) during exercise and commonly used, non-invasive measures of training load across sessions of varying duration and intensity and (2) build and evaluate prediction models to estimate CHO utilization and EE with the same training load measures and easily quantified individual factors.

The Relationship Between the Moderate-Heavy Boundary and Critical Speed in Running.

Purpose: Training characteristics such as duration, frequency, and intensity can be manipulated to optimize endurance performance, with an enduring interest in the role of training-intensity distribution to enhance training adaptations. Training intensity is typically separated into 3 zones, which align with the moderate-, heavy-, and severe-intensity domains. While estimates of the heavy- and severe-intensity boundary, that is, the critical speed (CS), can be derived from habitual training, determining the moderate-heavy boundary or first threshold (T1) requires testing, which can be costly and time-consuming.

Durability of the moderate-to-heavy-intensity transition is related to the effects of prolonged exercise on severe-intensity performance.

Purpose: Power output at the moderate-to-heavy-intensity transition decreases during prolonged exercise, and resilience to this has been termed 'durability'. The purpose of this study was to assess the relationship between durability and the effect of prolonged exercise on severe-intensity performance, and explore intramuscular correlates of durability.

Methods: On separate days, 13 well-trained cyclists and triathletes (V̇Opeak, 57.

Power output at the moderate-to-heavy intensity transition decreases in a non-linear fashion during prolonged exercise.

Purpose: The aims of this study were to: (i) describe the time course of the decrease in power output at the moderate-to-heavy intensity transition during prolonged exercise; (ii) investigate the association between durability of the moderate-to-heavy intensity transition and exercise capacity; and (iii) explore physiological correlates of durability of the moderate-to-heavy intensity transition.

Methods: Twelve trained cyclists (age: 40 ± 8 y, Opeak: 52.3 ± 5.

Locally applied heat stress during exercise training may promote adaptations to mitochondrial enzyme activities in skeletal muscle.

There is some evidence for temperature-dependent stimulation of mitochondrial biogenesis; however, the role of elevated muscle temperature during exercise in mitochondrial adaptation to training has not been studied in humans in vivo. The purpose of this study was to determine the role of elevating muscle temperature during exercise in temperate conditions through the application of mild, local heat stress on mitochondrial adaptations to endurance training. Eight endurance-trained males undertook 3 weeks of supervised cycling training, during which mild (~ 40 °C) heat stress was applied locally to the upper-leg musculature of one leg during all training sessions (HEAT), with the contralateral leg serving as the non-heated, exercising control (CON).

Kinetic Analysis, Potentiation, and Fatigue During Vertical and Horizontal Plyometric Training: An In-Depth Investigation Into Session Volume.

Unlabelled: Despite previous support for plyometric training, optimal dosing strategies remain unclear.

Purpose: To investigate vertical and horizontal jump kinetic performance following a low-volume plyometric stimulus with progressively increased session jump volume.

Methods: Sixteen academy rugby players (20.

The Weekly Periodization of Top 5 Tour de France General Classification Finishers: A Multiple Case Study.

Purpose: The aim of this study was to describe individual training characteristics, racing strategies, and periodization in preparation for the Tour de France in 2 world-class road cyclists finishing in the top 5 of the general classification.

Methods: Week-by-week power meter training and racing data of 2 (A and B) road cyclists (age: 29 and 23 y; maximum oxygen consumption: 83 and 81 mL·min-1·kg-1; and relative 20-min record power output: 6.9 and 6.

Prolonged exercise shifts ventilatory parameters at the moderate-to-heavy intensity transition.

Purpose: To quantify the effects of prolonged cycling on the rate of ventilation ([Formula: see text]), frequency of respiration (F), and tidal volume (V) associated with the moderate-to-heavy intensity transition.

Methods: Fourteen endurance-trained cyclists and triathletes (one female) completed an assessment of the moderate-to-heavy intensity transition, determined as the first ventilatory threshold (VT), before (PRE) and after (POST) two hours of moderate-intensity cycling. The power output, [Formula: see text], F, and V associated with VT were determined PRE and POST.

Skeletal muscle proteins involved in fatty acid transport influence fatty acid oxidation rates observed during exercise.

Several proteins are implicated in transmembrane fatty acid transport. The purpose of this study was to quantify the variation in fatty acid oxidation rates during exercise explained by skeletal muscle proteins involved in fatty acid transport. Seventeen endurance-trained males underwent a (i) fasted, incremental cycling test to estimate peak whole-body fatty acid oxidation rate (PFO), (ii) resting vastus lateralis microbiopsy, and (iii) 2 h of fed-state, moderate-intensity cycling to estimate whole-body fatty acid oxidation during fed-state exercise (FO).

Carbohydrate, but not fat, oxidation is reduced during moderate-intensity exercise performed in 33 vs. 18 °C at matched heart rates.

Purpose: Exposure to environmental heat stress increases carbohydrate oxidation and extracellular heat shock protein 70 (HSP70) concentrations during endurance exercise at matched absolute, external work rates. However, a reduction in absolute work rate typically occurs when unacclimated endurance athletes train and/or compete in hot environments. We sought to determine the effect of environmental heat stress on carbohydrate oxidation rates and plasma HSP70 expression during exercise at matched heart rates (HR).

Plasma Acidosis and Peak Power after a Supramaximal Trial in Elite Sprint and Endurance Cyclists: Effect of Bicarbonate.

Purpose: This study aimed to determine whether (i) a plasma acidosis contributes to a reduction of mechanical performance and (ii) bicarbonate supplementation blunts plasma acidosis and arterial oxygen desaturation to resist fatigue during the end spurt of a supramaximal trial in elite sprint and endurance cyclists.

Methods: Elite/world-class cyclists ( n = 6 sprint, n = 6 endurance) completed two randomized, double-blind, crossover trials at 105%V̇O 2peak simulating 3 min of a 4-km individual pursuit, 90 min after ingestion of 0.3 g·kg -1 BM sodium bicarbonate (BIC) or placebo (PLA).

Prolonged cycling reduces power output at the moderate-to-heavy intensity transition.

Purpose: To determine the effect of prolonged exercise on moderate-to-heavy intensity transition power output and heart rate.

Methods: Fourteen endurance-trained cyclists and triathletes took part in the present investigation (13 males, 1 female, V·Opeak 59.9 ± 6.

Decoupling of Internal and External Workload During a Marathon: An Analysis of Durability in 82,303 Recreational Runners.

Aim: This study characterised the decoupling of internal-to-external workload in marathon running and investigated whether decoupling magnitude and onset could improve predictions of marathon performance.

Methods: The decoupling of internal-to-external workload was calculated in 82,303 marathon runners (13,125 female). Internal workload was determined as a percentage of maximum heart rate, and external workload as speed relative to estimated critical speed (CS).

Peak fat oxidation is positively associated with vastus lateralis CD36 content, fed-state exercise fat oxidation, and endurance performance in trained males.

Purpose: Whole-body fat oxidation during exercise can be measured non-invasively during athlete profiling. Gaps in understanding exist in the relationships between fat oxidation during incremental fasted exercise and skeletal muscle parameters, endurance performance, and fat oxidation during prolonged fed-state exercise.

Methods: Seventeen endurance-trained males underwent a (i) fasted, incremental cycling test to assess peak whole-body fat oxidation (PFO), (ii) resting vastus lateralis microbiopsy, and (iii) 30-min maximal-effort cycling time-trial preceded by 2-h of fed-state moderate-intensity cycling to assess endurance performance and fed-state metabolism on separate occasions within one week.

Effects of short-term graded dietary carbohydrate intake on intramuscular and whole body metabolism during moderate-intensity exercise.

Altering dietary carbohydrate (CHO) intake modulates fuel utilization during exercise. However, there has been no systematic evaluation of metabolic responses to graded changes in short-term (< 1 wk) dietary CHO intake. Thirteen active men performed interval running exercise combined with isocaloric diets over 3 days before evaluation of metabolic responses to 60-min running at 65% V̇O on three occasions.

Temperate performance and metabolic adaptations following endurance training performed under environmental heat stress.

Endurance athletes are frequently exposed to environmental heat stress during training. We investigated whether exposure to 33°C during training would improve endurance performance in temperate conditions and stimulate mitochondrial adaptations. Seventeen endurance-trained males were randomly assigned to perform a 3-week training intervention in 18°C (TEMP) or 33°C (HEAT).

The Importance of 'Durability' in the Physiological Profiling of Endurance Athletes.

Profiling physiological attributes is an important role for applied exercise physiologists working with endurance athletes. These attributes are typically assessed in well-rested athletes. However, as has been demonstrated in the literature and supported by field data presented here, the attributes measured during routine physiological-profiling assessments are not static, but change over time during prolonged exercise.

Autonomic and Perceptual Responses to Induction of a Ketogenic Diet in Free-Living Endurance Athletes: A Randomized, Crossover Trial.

Purpose: Considerable interindividual heterogeneity has been observed in endurance performance responses following induction of a ketogenic diet (KD). It is plausible that a physiological stress response in the period following the dramatic dietary shift associated with transition to a KD may explain this heterogeneity.

Methods: In a randomized, crossover study design, 8 trained male runners completed an incremental exercise test and ran to exhaustion at 70%VO2max before and after a 31-day rigorously controlled habitual diet or KD intervention, and recorded heart rate variability (root mean square of the sum of successive differences in R-R intervals [rMSSD]) upon waking each morning along with the recovery-stress questionnaire for athletes each week.