You've done the reverse of my full team cardio trick which significantly boost performance.
The trick is basically letting the whole team or at least the starting lineup to reach condition 90%+ (95%+ even better), do a full team normal cardio (-6%) and use rest all (that cost 6~8 green depend on your team size) before the match starts.
Player who train alone a lot trend to have uncontrollable form, to me training player individually is a bit risky if you don't figure out his breaking point already. Although powertraining usually result in good form, overtraining can cause form to plummet.