I am trying to use radar charts to present fitness test results to each athlete from my school`s rugby team. I am dealing with one issue:

I`m aware that you need to use the formula =(athlete score-average score)/ STDEV to find the Z score for each test.

I`m also aware that the Z score for the group`s average for each test will be 0. So, so far I am able to put the athletes scores on the radar chart as well as the group`s average scores on the same chart so that the athlete can see where he is in relation to the group (better or worse in various tests than his team mates).

So for example, if the athlete`s bench press is 75 and the group`s 80,7 and STDEV is 10,0 then the Z score will be =(75-80,7)/10= -0,57

My question is: if I want to put another score, which would be each test`s goal (benchmark) so for example, each athletes goal is to bench press 90kg in X weeks time, how do I find the Z scores for this?

In a book called High Performance Training for Sports it says to use this formula =(athlete`s score- benchmark score)/STDEV.

But if I do this it will be =(75-90)/10= -1,5. Which does not make sense?

What if I use the same formula as in the beginning, but instead of the athlete`s score I would type 90 (the benchmark), then it would look like this =(90-80,7)/10= 0,93. But am I allowed to use the same STDEV? And would this be a correct way to calculate it?

I know it sounds confusing, but any feedback would be much appreciated.

Thanks!