| Summary: | The purpose of this investigation was to compare the ventilatory threshold (T(vent)) with the lactate threshold (T(lact)) during 60 minutes of steady-state exercise at the calculated thresholds. Eight trained, male
cyclists (mean age=23.3 yrs, ht=176.4 cm, wt=70.7 kg, VO₂max=61.02
ml/kg‧minˉ¹) performed a 23 W/min progressive intensity cycling test for determination of T(lact) and T(vent). T(vent) was determined by the non-linear increase in excess CO₂ (ExCO₂) while T(lact) was calculated by
the 'individual anaerobic threshold' (IAT) method. Subsequently, subjects performed up to 60 minutes steady-state exercise at the threshold workloads. Results at T(vent) and T(lact) indicate significant differences
(p<0.01; T(lact)>T(vent)) between VO₂, ExCO₂, HR, [BLa] and workload as
calculated by Hotelling's T²-test. During the steady state exercise at each
specified workload, VO₂, [BLa], heart rate and ExCO₂ were measured at 15
minute intervals. All subjects completed the steady-state exercise at T(vent) (VSS) while only 2 subjects completed the steady-state exercise at T(lact) (LSS) (avg time=48.4 min). Comparison of metabolic variables
using MANOVA and multiple comparisons revealed significant differences between VSS and LSS for HR and VO₂ at all time intervals, for [BLa] at 30
and 45 minute intervals and for ExCO₂ at the 30 minute interval. Furthermore, examination of [BLa] over time using trend analysis revealed a stabilization during VSS ([formula omitted]=3.05 mmol‧Lˉ¹) whereas [BLa] continuously increased over time during LSS. Findings indicate that T(lact) (IAT method) overestimates the ability to perform prolonged work over 45 min. while T(vent) (ExCO) allows for steady-state exercise greater than 60 minutes. === Education, Faculty of === Curriculum and Pedagogy (EDCP), Department of === Graduate
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