Fitness won't be reset...

1) Quit training on Maximum.
2) Never even look at Maximum training until you know how you will go about getting your energy back.
3) Even after seeing how you will go about getting your energy back - Maximum training is probably a very bad idea for 99% of the people who even looked at it.

That said - now that your guys are tired, let's look at the FAQ to see what it says about training and energy:

Maximum: + 6 training points and - 5 to - 10 fitness points High: + 2 training points and - 3 to - 6 fitness points Average: 0 training points and 0 to + 2 fitness points Low: - 2 training points and + 3 to + 6 fitness points Very low: - 4 training points and + 5 to + 6 fitness points

Also in the suggestions forum there is a stickied topic which talks about changes that the mods will try to implement at some point in the future:

26.) Rest Week for players with low fitness 27.) Limit how low fitness can fall before a player has an automatic week off

So there will be an option in the future, to help individual players.. but really - your best bet is to train on "Low" Training for the next 6-7 weeks to get your guys' fitness back up to 90% or higher.