Earlier quoted context omitted.
50W is nothing, and 500W isn’t really a sprint. For an adult male, you should be pushing 1000-2000 over 20 second sprints. Walking slightly uphill is probably more intense than a 50w bike.
So? If the article says 50/500W then I’d say that’s the best objective description of the effort level.
It is an objective description of the power they produced. NOT their effort level. Their effort level would be established via their BPM, perceived extersion, lactate levels, etc etc