Influence of repeated sprint training on pulmonary O₂ uptake and muscle deoxygenation kinetics in humans

Abstract

We hypothesized that a short-term training program involving repeated all-out sprint training (RST) would be more effective than work-matched, low-intensity endurance training (ET) in enhancing the kinetics of oxygen uptake (Vo(2)) and muscle deoxygenation {deoxyhemoglobin concentration ([HHb])} following the onset of exercise. Twenty-four recreationally active subjects (15 men, mean +/- SD: age 21 +/- 4 yr, height 173 +/- 9 cm, body mass 71 +/- 11 kg) were allocated to one of three groups: RST, which completed six sessions of four to seven 30-s RSTs; ET, which completed six sessions of work-matched, moderate-intensity cycling; and a control group (CON). All subjects completed moderate-intensity and severe-intensity "step" exercise transitions before (Pre) and after the 2-wk intervention period (Post). Following RST, [HHb] kinetics were speeded, and the amplitude of the [HHb] response was increased during both moderate and severe exercise (P < 0.05); the phase II Vo(2) kinetics were accelerated for both moderate (Pre: 28 +/- 8, Post: 21 +/- 8 s; P < 0.01) and severe (Pre: 29 +/- 5, Post: 23 +/- 5 s; P < 0.05) exercise; the amplitude of the Vo(2) slow component was reduced (Pre: 0.52 +/- 0.19, Post: 0.40 +/- 0.17 l/min; P < 0.01); and exercise tolerance during severe exercise was improved by 53% (Pre: 700 +/- 234, Post: 1,074 +/- 431 s; P < 0.01). None of these parameters was significantly altered in the ET and CON groups. Six sessions of RST, but not ET, resulted in changes in [HHb] kinetics consistent with enhanced fractional muscle O(2) extraction, faster Vo(2) kinetics, and an increased tolerance to high-intensity exercise.

Muscle Oxygen Extraction Is Higher during Constant Work Exercise than during Incremental Ramp Exercise

“…The HHb levels during CWE exceeded those observed (Neary et al 2001;DeLorey et al 2003;Grassi et al 2003) because of its higher WR during CWE. In the present study, differences in HHb values during the end phase, from 90% to 100% of V 4 O 2max , may be because of the "HHb slow component" during CWE (Jones et al 2006;Bailey et al 2009;), a progressive increase in HHb throughout the steady state portion of the exercise, and "the plateau point" during IRE (Legrand et al 2007;Boone et al 2009;Osawa et al 2011;Spencer et al 2012). In the present study, the typical HHb kinetics (Fig.…”

Dietary nitrate supplementation reduces the O2cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans

“…The V O2 peak was taken as the highest 30-s average value attained before the subject's volitional exhaustion. The GET was determined as described previously (1,5). The work rates that would require 80% of the GET (moderate exercise) and 70% ⌬ (70% of the difference between the power output at the GET and V O2 peak, severe exercise) were subsequently calculated, with account taken of the mean response time for V O2 during ramp exercise (i.e., two-thirds of the ramp rate was deducted from the power output at GET and peak; Ref.…”

“…During all tests, pulmonary gas exchange and ventilation were measured continuously using a portable metabolic cart (MetaMax 3B, Cortex Biophysik, Leipzig, Germany), as described previously (1). A turbine digital transducer measured inspired and expired airflow, while an electrochemical cell O2 analyzer and an infrared CO2 analyzer simultaneously measured expired gases.…”

“…Whereas it is known that interventions such as training and the inspiration of hyperoxic gas can reduce the O 2 cost of heavy (above the GET but below critical power; Ref. 52) and severe (above critical power) exercise by reducing the amplitude of the V O 2 slow component, the steady-state V O 2 during moderate exercise is unaffected by these and other interventions in healthy humans (1,15,36,51,65). Surprisingly, however, it was recently reported that 6 days of dietary supplementation with pharmacological sodium nitrate reduced the O 2 cost of submaximal cycling at work rates expected to require 45-80% maximum V O 2 (V O 2max ) (45).…”

Dose-dependent effects of dietary nitrate on the oxygen cost of moderate-intensity exercise: Acute vs. chronic supplementation

“…The O 2peak was calculated as the highest 30-s mean value attained before the subject's volitional exhaustion. The GET was determined as described previously [15,16]. The work rate that would require 80 % of the GET (moderate exercise) was then calculated, with account taken of the mean response time for O 2 during ramp exercise (i.e.…”