Lactate and gas exchange responses to incremental and steady state running.

Abstract

This study compared the oxygen uptake (VO2) and running velocity at which the lactate threshold (LT), the ventilatory threshold (VT), and the maximal lactate steady state (MSSLA), and the maximal VO2 steady state (MSSVO2) occurred in 11 trained male runners (mean age = 22.4 years, range 18-28 years). Each underwent an incremental treadmill test to exhaustion. The LT was defined by a systematic, continuous increase in arterialised venous blood lactate; the VT was determined by an abrupt rise in VE.VO2(-1) without an increase in VE.VCO2(-1). Each subject also completed a series of steady state treadmill runs of 20 minutes duration. The MSSLA was determined as the highest velocity and VO2 at which lactate concentration increased by less than 0.2 mmol.l-1 from minute 10 to minute 20. The MSSVO2 was determined as the highest velocity or VO2 at which a steady state in VO2 was not delayed for more than 3 minutes (with a steady state defined as VO2 within 0.2 l.min-1 of the average VO2 over the last 10 minutes of each test). Each subject also completed a 5 km time trial run to assess performance. No significant differences were found among the four variables expressed either as VO2 or velocity. Significant correlations were found between MSSLA and MSSVO2 (r = 0.74) expressed as VO2, and between MSSLA and MSSVO2 (r = 0.90), MSSVO2 and VT (r = 0.70) and MSSLA and VT (r = 0.67) expressed as velocity. A stepwise regression analysis found MSSLA (expressed as velocity) to be the best predictor of 5 km performance (r = 0.87). It was concluded that (a) MSSLA and MSSVO2 are closely related, and (b) MSSLA is a good predictor of performance and may be an important, objective measure of cardiorespiratory endurance capacity.

Methodological aspects of maximal lactate steady state—implications for performance testing

“…Nevertheless, various concepts of the anaerobic threshold do not necessarily provide identical levels of lactate and/or workloads at MLSS and/or MLSS workload (Beneke 1995). Consequently, the determination of MLSS requires several subsequent constant submaximal load tests performed on separate days (Aunola and Rusko 1992;Beneke 1995;Haverty et al 1988;Heck 1990;Mocellin et al 1990;Urhausen et al 1993).…”

Influência da forma de indução à acidose na determinação da intensidade de lactato mínimo em corredores de longa distância

“…A cada cinco minutos são coletadas amostras de sangue para determinação das concentrações sanguíneas de lactato. Após essa fase, a curva lactato versus tempo de exercício é plotada com o intuito de definir a intensidade correspondente à MFEL na qual não há aumento igual ou superior a 1mM (12)(13) ou 0,2-0,5mM (14)(15) do 10º ao 30º minuto de exercício. Embora seja um método muito preciso, torna-se inviável no âmbito esportivo, devido ao elevado custo operacional e à grande quantidade de tempo necessária ao atleta para realização das avaliações (1) .…”

Comparação entre métodos invasivos e não invasivo de determinação da capacidade aeróbia em futebolistas profissionais

“…For instance, Haverty et al (13) defined the intensity corresponding to MLSS as the highest running velocity in which the blood lactate presented no elevation above 0.2 mmol/L between the tenth and the twentieth minutes of a 20-minutes test. However, this time period does not seem to be sufficient to consolidate the lactacidemia steady state (12) .…”

“…The appraised performs 4-6 sessions of different intensities with minimum intervals of 24 hours. After each session, the lactacidemia x time of exercise curve is plotted and the iAT is found in the maximum lactate concentration, where there is no increase equal or greater than 1 mmol/L (10,11) or 0.2-0.5 mmol/L (12,13) from the tenth to the thirtieth minute of exercise. Despite being a very accurate method, it becomes unfeasible in the sportive environment due to the high operational cost and to the long time spent by the athlete to perform the evaluations.…”