It sounds like an ANCOVA may be appropriate, but I'm not sure what your question was, you explained your intentions wonderfully, but didn't really ask a question. Were you asking what type of analysis to use? I would start with ANCOVA, though you might have to use an ordinal logistic regression, depending on the distribution of your DV.
I´m investigating differences at my DV´s (Psicological variables - likert scale) by the regularity of exercise practice (3 levels) by group ages (4 groups).
As i have two different exercise contexts, i´d like to compare the VD´s-Exercise-age relations between the two contexts, controling the effects of each context of exercise on each other?
Which approach should i use?
Thanks a lot for who were able to led some light to this problem!