I suppose the question is over the nature of forced.
I have a rowing machine which gives me a readout of speed/distance/cadence etc.
I 'force' myself to maintain a certain speed for a certain time even when it is quite uncomfortable. Is that sufficient for the 'forced' effect to come into play. I suspect it is.
Do you work out to the point of muscle failure? Do you maintain a speed so grueling that you literally can't row at all after a certain point? That's my interpretation of "forced," at least as experienced in my PT. Granted, I don't know what "forced" meant in the context of the study being talked about in this article. Accordngly, I can only guess at it. (No desire to play "No True Scotsman" on this, I assure you.)
In the article they said they tested them and if you went around 60 RPM on the bike the forced part was at 90 RPM. So they could measure swim pace then have them train at a higher pace.
I have a rowing machine which gives me a readout of speed/distance/cadence etc.
I 'force' myself to maintain a certain speed for a certain time even when it is quite uncomfortable. Is that sufficient for the 'forced' effect to come into play. I suspect it is.