Just try until you get it, next patreon build(30th of this month) will make it easier ^-^
Viewing post in Triple R: Rehabilitation Rational Ruined comments
Just a word of advice for anyone reading through the comments with the same question-
I beat it rather easily by working only on the treadmill, and ABUSING the Dodge function (regenerates 10 stamina)
Essentially, I would use Dash for every attack, and when the option to Dodge or Counterattack appeared, I always chose Dodge. Using this method, I only had to attack it once, to beat it, but somebody else might have to try a couple times.