Effects of Caffeine Ingestion on Pulmonary V˙O2 Kinetics and Muscle Fatigue During Severe-Intensity Cycling Exercise.

Introduction: This study aimed to analyze the effect of caffeine (CAF) intake on pulmonary oxygen uptake (V˙O2) kinetics, muscle fatigue, and physiological and perceptual parameters during severe-intensity cycling exercise.

Methods: Twelve physically active men (age: 26 ± 5 years; V˙O2peak: 46.7 ± 7.

No Combined Effect of Caffeinated Chewing Gum and Priming Exercise on Oxygen Uptake and Muscle Near-Infrared Spectroscopy-Derived Kinetics: A Double-Blind Randomized Crossover Placebo-Controlled Trial in Cyclists.

This study aimed to investigate the effects of caffeine ingestion by chewing gum (GUMCAF) combined with priming exercise on pulmonary oxygen uptake (V˙O2) and near-infrared spectroscopy-derived muscle oxygen extraction (HHb + Mb) kinetics during cycling performed in a severe-intensity domain. Fifteen trained cyclists completed four visits: two under a placebo gum (GUMPLA) and two under GUMCAF ingestion. Each visit consisted of two square-wave cycling bouts at Δ70 intensity (70% of difference between the V˙O2 at first ventilatory threshold and V˙O2max) with duration of 6 min each and 5 min of passive rest between the bouts.

Effects of high-intensity interval training and resistance training on physiological parameters and performance of well-trained runners: A randomized controlled trial.

This study aimed to verify the effects of 4 weeks of high-intensity interval training (HIIT), heavy (HRT) and explosive (ERT) resistance training on aerobic, anaerobic and neuromuscular parameters and performance of well-trained runners. Twenty-six male athletes were divided into HIIT ( = 10), HRT ( = 7) and ERT ( = 9) groups. Maximal oxygen uptake () and the corresponding velocity (), anaerobic threshold (AT), running economy (RE), oxygen uptake kinetics, lower-body strength (1RM) and power (CMJ), and the 1500m and 5000m time-trial (TT) were determined.

Energy metabolism and muscle activation heterogeneity explain slow component and muscle fatigue of cycling at different intensities.

New Findings: What is the central question of this study? What are the physiological mechanisms underlying muscle fatigue and the increase in the O cost per unit of work during high-intensity exercise? What is the main finding and its importance? Muscle fatigue happens before, and does not explain, the slow component ( ), but they share the same origin. Muscle activation heterogeneity is associated with muscle fatigue and . Knowing this may improve training prescriptions for healthy people leading to improved public health outcomes.

Muscle Oxidative Capacity Is Associated With Physiological Parameters in Trained Rowers.

The muscle oxygen uptake () kinetics following exercise, measured by near-infrared spectroscopy, has been used as a functional evaluation of muscle oxidative metabolism. This study aimed to determine the off-kinetics and verify the relationship of the recovery rate of () with time-trial performance and different aerobic parameters in trained rowers. Eleven male rowers (age: 20 ± 3 years; : 4.

Heart rate variability kinetics during different intensity domains of cycling exercise in healthy subjects.

The purpose of this study was to verify the heart rate variability (HRV) and heart rate (HR) kinetics during the fundamental phase in different intensity domains of cycling exercise. Fourteen males performed five exercise sessions: (1) maximal incremental cycling test; (2) two rest-to-exercise transitions for each intensity domain, that is, heavy (Δ30) and severe (Δ60) domains. HRV markers (SD1 and SD2) and HR kinetics in the fundamental phase were analyzed by first-order exponential fitting.

Physiological responses and cycle characteristics during double-poling versus diagonal-stride roller-skiing in junior cross-country skiers.

Purpose: This study aimed to compare physiological factors and cycle characteristics during cross-country (XC) roller-skiing at matched inclines and speeds using the double-poling (DP) and diagonal-stride (DS) sub-techniques in junior female and male XC skiers.

Methods: Twenty-three well-trained junior XC skiers (11 women, 12 men; age 18.2 ± 1.

Modeling the depletion and reconstitution of W': Effects of prior exercise on cycling tolerance.

Thirteen healthy male subjects (age 28 ± 7 years) performed tests for critical power and W' determination and two square-wave high-intensity exercises until exhaustion either with prior very-heavy intensity cycling (EXP) or without (CON). Prior exercise bout induced a depletion of 60 % of W'. After 10 min of recovery, W' reconstitution was not fully achieved (∼ 92 %).

Skeletal muscle V̇o kinetics by the NIRS repeated occlusions method during the recovery from cycle ergometer exercise.

Near-infrared spectroscopy (NIRS) has been utilized as a noninvasive method to evaluate skeletal muscle mitochondrial function in humans, by calculating muscle V̇o (V̇o) recovery (off-) kinetics following short light-intensity plantar flexion exercise. The aim of the present study was to determine V̇o off- kinetics following standard cycle ergometer exercise of different intensities. Fifteen young physically active healthy men performed an incremental exercise (INCR) up to exhaustion and two repetitions of constant work-rate (CWR) exercises at 80% of gas exchange threshold (GET; MODERATE) and at 40% of the difference between GET and peak pulmonary V̇o (V̇o; HEAVY).

Applicability of Dmax Method on Heart Rate Variability to Estimate the Lactate Thresholds in Male Runners.

Introduction: The purpose of this study was to evaluate the application of the Dmax method on heart rate variability (HRV) to estimate the lactate thresholds (LT), during a maximal incremental running test (MIRT).

Methods: Nineteen male runners performed two MIRTs, with the initial speed at 8 km·h and increments of 1 km·h every 3 minutes, until exhaustion. Measures of HRV and blood lactate concentrations were obtained, and lactate (LT and LT) and HRV (HRVT and HRVT) thresholds were identified.

Similar maximal oxygen uptake assessment from a step cycling incremental test and verification tests on the same or different day.

The present study aimed to compare maximal oxygen uptake of a step incremental test with time to exhaustion verification tests () performed on the same or different day. Nineteen recreationally trained cyclists (age: 23 ± 2.7 years; maximal oxygen uptake: 48.

Changes in VO Kinetics After Elevated Baseline Do Not Necessarily Reflect Alterations in Muscle Force Production in Both Sexes.

A link between muscle fatigue, decreased efficiency and the slow component of oxygen uptake (VOsc) has been suggested. However, a cause-effect relationship remains to be elucidated. Although alterations in VO kinetics after elevated baseline work rate have previously been reported, to date no study has observed the effect on muscle force production (MFP) behavior considering physiological differences between male and female subjects.

Prediction of peak O in Children and Adolescents With HIV From an Incremental Cycle Ergometer Test.

Purpose: To examine the capacity of physiological variables and performance to predict peak oxygen consumption (peak O) in children and adolescents living with HIV.

Method: Sixty-five children and adolescents living with HIV (30 boys) aged 8-15 years, participated in the study. Peak O was measured by breath-by-breath respiratory exchange during an incremental cycle ergometer until volitional exhaustion.

Thigh Ischemia-Reperfusion Model Does Not Accelerate Pulmonary VO Kinetics at High Intensity Cycling Exercise.

We aimed to investigate the effect of a priming ischemia-reperfusion (IR) model on the kinetics of pulmonary oxygen uptake (VO) and cardiopulmonary parameters after high-intensity exercise. Our primary outcome was the overall VO kinetics and secondary outcomes were heart rate (HR) and O pulse kinetics. We hypothesized that the IR model would accelerate VO and cardiopulmonary kinetics during the exercise.

The effects of priming exercise on the V̇O slow component and the time-course of muscle fatigue during very-heavy-intensity exercise in humans.

We hypothesized that prior exercise would attenuate the muscle fatigue accompanied by oxygen uptake slow-component (V̇O) behavior during a subsequent very-heavy (VH)-intensity cycling exercise. Thirteen healthy male subjects performed tests to determine the critical power (CP) and the fixed amount of work above CP ([Formula: see text]) and performed 6 square-wave bouts until 3 or 8 min, each at a work rate set to deplete 70% [Formula: see text] in 8 min, with a maximal isokinetic effort before and after the conditions without (VH) and with prior exercise (VH), to measure the cycling peak torque decrement. The V̇O magnitude at 3 min (VH = 0.

Physiological Responses During the Time Limit at 100% of the Peak Velocity in the Carminatti's Test in Futsal Players.

The aim of this study was to investigate the physiological responses during the time limit at the intensity of the peak velocity of the Carminatti's test (T-CAR). Ten professional futsal players (age, 27.4 ± 5.

Are the oxygen uptake and heart rate off-kinetics influenced by the intensity of prior exercise?

The aim of this study was to investigate the effect of prior exercise on the heart rate (HR) and oxygen uptake (VO2) off-kinetics after a subsequent high-intensity running exercise. Thirteen male futsal players (age 22.8±6.

Rate of utilization of a given fraction of W' (the curvature constant of the power-duration relationship) does not affect fatigue during severe-intensity exercise.

What is the central question of this study? Does the rate of utilization of W' (the curvature constant of the power-duration relationship) affect fatigue during severe-intensity exercise? What is the main finding and its importance? The magnitude of fatigue after two severe-intensity exercises designed to deplete the same fraction of W' (70%) at two different rates of utilization (fast versus slow) was similar after both exercises. Moreover, the magnitude of fatigue was related to critical power (CP), supporting the contention that CP is a key determinant in fatigue development during high-intensity exercise. Thus, the CP model is a suitable approach to investigate fatigue mechanisms during high-intensity exercise.

Maximal power output during incremental cycling test is dependent on the curvature constant of the power-time relationship.

The aim of this study was to investigate whether the maximal power output (Pmax) during an incremental test was dependent on the curvature constant (W') of the power-time relationship. Thirty healthy male subjects (maximal oxygen uptake = 3.58 ± 0.