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Can ventilation be used as a non-invasive measure of lactate clearance?

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  • Qp Physiology
  • Biology


The purpose of this study was to determine whether the rate of lactate clearance can be determined non-invasively through a potential relationship with ventilation. Current research has given lactate the status of an important metabolic substrate as opposed to a fatiguing agent, however, the lactate threshold and rate of lactate clearance is still used as a physiological marker of exercise intensity and metabolic stress. Current methods used to measure lactate clearance are involved and costly therefore alternative procedures would be useful and the aim of this investigation is to establish whether a non-invasive predictor of lactate clearance has value, particularly in high intensity, team sports. 14 youth professional football players mean age 17±0.7 years, body mass 75±8 Kg and height 182±7 cm were recruited to this study. The participants completed six months of full-time professional football training before undertaking a treadmill test to volitional exhaustion at 10 Kmh-1 with an initial gradient of 0%, increasing by 2% every 2 minutes. Oxygen uptake ( O2), carbon dioxide output ( CO2), ventilation ( e) and respiratory exchange ratio (RER) were recorded continuously throughout the test. The player’s rating of perceived exertion (RPE) was recorded at the end of each 2 minute work rate increment using a Borg scale. Capillary blood samples were collected at rest, at peak exercise and at 1, 3, 5 and 15 minutes during an active recovery period (where players walked at 5 on a 1% gradient).The capillary blood samples were analysed immediately for blood lactate concentration (b[La]). At the time of the maximal exercise test, O2peak was 58.8±9.9, CO2peak was 4.97±0.9 l.min-1 and epeak was 148.65± 23.5 l.min-1. Ventilatory threshold (VT) was derived from the O2/ CO2 relationship using the V-slope method and was 62.5±8.7 % of O2peak. Lactate clearance was expressed as the half-time for peak b[La] to return to resting b[La] (T½ b[La]) and mean T½ b[La] was 11.7±5.7 min. There was a significant positive correlation between T½ b[La] and epeak (r = 0.65; p < 0.05). Importantly, the time course of lactate clearance was a single exponential decay in these athletes and so T½ b[La] was the best discriminator of lactate clearance. This data demonstrates that full-time training for football may not provide an appropriate stimulus to maximise the physiological processes of lactate clearance. This is likely to have an impact on the ability of players to recover from the intermittent, high intensity, anaerobic bouts of exercise common in the sport. Peak ventilation is a significant predictor of lactate clearance in these athletes and may provide an appropriate mechanism to monitor targeted training interventions to improve lactate clearance.

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