After completing progressive CPET to exhaustion, we can estimate ventilatory thresholds (VT1, VT2) and asses peak oxygen uptake (VO2 peak). At each stage, we have data about oxygen uptake (VO2) and load (watt). Regarding hypothetical examples below:

Subject A

VT1 - 1500ml/min VO2 and 200 watts --> VO2/load=7.5 ml/min/watt

VT2 - 2000ml/min VO2 and 300 watts --> VO2/load=6.66 ml/min/watt

Peak - 2500ml/min VO2 and 400 watts --> VO2/load=6.25 ml/min/watt

Subject B:

VT1 - 1000ml/min VO2 and 200 watts --> VO2/load=5 ml/min/watt

VT2 - 1500ml/min VO2 and 300 watts --> VO2/load=5 ml/min/watt

Peak - 2000ml/min VO2 and 300 watts --> VO2/load=5ml/ml/min/watt

Can we say that the effectiveness/efficiency of subject B is better than A (at the same body weight or when normalized) or do I have to use the slope calculation? For example, in a review by Mazaheri et al. Cardiopulmonary Exercise Test Parameters in Athletic Population: A Review. Journal of Clinical Medicine 2021;10:5073. https://doi.org/10.3390/jcm10215073 they show slope as the parameter of exercise economy. I couldn't find any paper using VO2/load ratio at specific ventilatory thresholds, so I wonder if it would be justified to use it as an index of effectiveness or as cost of power generation?