Purpose: This study was designed to identify the lactate threshold (LT) and first ventilatory threshold (VT1 ) in a graded resistance half-squat test and determine whether both thresholds are produced at the same workload. A further goal was to compare the visual inspection and algorithm adjustment methods of detecting both thresholds during graded resistance exercise.
Methods: Twenty-four young men completed two test sessions 48 h apart; (i) the one-repetition maximum (1RM) was determined, (ii) an incremental load test was performed to locate LT and VT1 . VT1 was calculated in three different ways based on pulmonary ventilation, the ventilatory equivalent of oxygen or the end-tidal oxygen pressure (as VT1 -VE, VT1 -VE·VO2-1 or VT1 -PetO2, respectively).
Results: LT and VT1 were located at the same intensity of exercise during the incremental load test. Using the algorithm method, the LT and VT1 -VE were estimated at 24·8 ± 4·8% 1RM (50·6 ± 10·5 kg) and 23·7 ± 4·8% 1RM (48·4 ± 10·0 kg), respectively; the difference between the two values being non-significant (P = 0·127). In addition, positive correlation was observed between the two thresholds (r = 0·761; P<0·001; intraclass correlation coefficient (ICC) (0·864). The visual inspection and algorithm adjustment methods provided similar LT and VT1 values (r > 0·796; ICC > 0·885).
Conclusions: The LT and VT1 were readily located during the incremental load half-squat test at similar workloads using both the visual inspection and algorithm adjustment methods. Both thresholds served to define two physiological stages (I, II) corresponding to the zones described for endurance exercise. Thus, both LT and VT1 could be used to prescribe the same intensity of resistance half-squat exercise.
Keywords: aerobic capacity; algorithm adjustment method; anaerobic threshold; graded exercise test; strength training; visual inspection method.
© 2016 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.