Perceptions of capacity, fatigue, and their psychophysics: Examining construct equivalence and the relationship between actual capacity and perception of capacity during resisted elbow flexion tasks [Review]

Perceptions of capacity, fatigue, and their psychophysics Overall, this is a simple and interesting study that is of added value to the literature. Below are a few thoughts and suggestions that the authors may or may not act upon, as none are critical. 1. The introduction is well-written and clear. 2. Section 2.1 is a little vague. I suggest adding more information. For example, how many sessions did subjects attend in total? What was done with the dumbbell data? What was the rationale behind 25 reps? The differences between experiments can be highlighted a little better, and mainly, the timing of when the self-reports were provided can be clarified. For example, what does “…and then just prior to and immediately completing each test.” Mean? 3. Section 2.3 – I appreciate the attempt to differentiate between the scales so participants would not view them as the inverse of one another. However, here, and surely in the discussion, the fact that this possibility may have occurred requires some attention. That is to say, the observed relationships may have been influenced by subjects attempting to appeal to the experimenter. A qualitative assessment of sorts could have helped. I also see the benefits in the approach taken in which the upper values of the scales were not anchored, thus allowing subjects to interpret them as they saw fit. However, this approach also has some limitations, which I think would be appropriate to acknowledge. Fatigue, for example, can be interpreted in many ways, and without providing some explicit definitions, there is a greater chance that subjects may confound it with other experiences. The strength of the observed relationship partially refutes this point, yet, in view of my previous point, that subjects may have wanted to appeal to the experimenter should be kept in mind. The lack of clear anchoring could also serve as an explanation for the weaker relationship observed between actual and perceived capacity. This was partly touched upon in the discussion, but I think that doing so more explicitly, as an additional potential explanation alongside the proposed one, is warranted. 4. Section 2.5 is detailed and rich. I would wonder if moving sections 2.5.1 and 2.5.2 would better fit the supplementary. 5. The Discussion is well written. I find the argument that “… any observed psychophysical relationship between actual effort and perception of effort is likely to manifest operationally weak identity at best (i.e., assuming no bias).” to be too strong and one that I mostly disagree with, as a number of studies reported very strong relationships between actual and perceived effort. I think a fairer description is that the relationship is directionally ordered and, depending on the study, may be weak to very strong. The strength of such relationships likely depends on the exercise modality, explanations, anchoring procedures, and more. And again, the weaker relationships observed in the current study may relate to the fact that capacity was defined and anchored to the task at hand.