The effect of increasing work rate amplitudes from a common metabolic baseline on the kinetic response of V̇o, blood flow, and muscle deoxygenation.

A step-transition in external work rate (WR) increases pulmonary O uptake (V̇o) in a monoexponential fashion. Although the rate of this increase, quantified by the time constant (τ), has frequently been shown to be similar between multiple different WR amplitudes (ΔWR), the adjustment of O delivery to the muscle (via blood flow; BF), a potential regulator of V̇o kinetics, has not been extensively studied. To investigate the role of BF on V̇o kinetics, 10 participants performed step-transitions on a knee-extension ergometer from a common baseline WR (3 W) to: 24, 33, 45, 54, and 66 W.

Coupling of [Formula: see text] and [Formula: see text] kinetics: insights from multiple exercise transitions below the estimated lactate threshold.

During a step-change in exercise power output (PO), ventilation ([Formula: see text]) increases with a similar time course to the rate of carbon dioxide delivery to the lungs ([Formula: see text]). To test the strength of this coupling, we compared [Formula: see text] and [Formula: see text] kinetics from ten independent exercise transitions performed within the moderate-intensity domain. Thirteen males completed 3-5 repetitions of ∆40 W step transitions initiated from 20, 40, 60, 80, 100, and 120 W on a cycle ergometer.

Data analysis technique influences blood flow kinetics parameter estimates for moderate- and heavy-intensity exercise transitions.

New Findings: What is the central question of this study? During exercise, there are fluctuations in conduit artery blood flow (BF) caused by both cardiac and muscle contraction-relaxation cycles. What is the optimal method to process Doppler ultrasound-measured BF for the purpose of characterizing the dynamic response of BF during step-transitions in exercise? What is the main finding and its importance? Continuous BF data were processed in relation to either cardiac or muscle contraction-relaxation cycles and computed based on 'binned' or 'rolling' averages over one, two or five consecutive cycles. Kinetics characterization revealed no data processing technique-specific differences in steady-state BF, but variability in the rapidity at which BF attained steady-state (i.

Identification of Non-Invasive Exercise Thresholds: Methods, Strategies, and an Online App.

During incremental exercise, two thresholds may be identified from standard gas exchange and ventilatory measurements. The first signifies the onset of blood lactate accumulation (the lactate threshold, LT) and the second the onset of metabolic acidosis (the respiratory compensation point, RCP). The ability to explain why these thresholds occur and how they are identified, non-invasively, from pulmonary gas exchange and ventilatory variables is fundamental to the field of exercise physiology and requisite to the understanding of core concepts including exercise intensity, assessment, prescription, and performance.

Power reserve following ramp-incremental cycling to exhaustion: implications for muscle fatigue and function.

In ramp-incremental cycling exercise, some individuals are capable of producing power output (PO) in excess of that produced at their limit of tolerance (LoT) whereas others cannot. This study sought to describe the 1) prevalence of a "power reserve" within a group of young men ( n = 21; mean ± SD: age 25 ± 4 yr; V̇o 45 ± 8 ml·kg·min); and 2) muscle fatigue characteristics of those with and without a power reserve. "Power reserve" (ΔPReserve) was determined as the difference between peak PO achieved during a ramp-incremental test to exhaustion and maximal, single-leg isokinetic dynamometer power determined within 45 s of completing the ramp-incremental test.