GEEGLM for longitudinal data in the sport sciences

I have measured power output in a small group (n=7) of elite athletes before and after training as an indicator of neuromuscular fatigue. This was repeated on many sessions (n=6) over the course of a training block. I am particularly interested in assessing the change in power output from pre-training to post-training.

Originally I had planned to take a mean pre-training value and mean post-training value for each subject over the 6 sessions, and then perform a paired t-test to assess the change.

However, I recently began reading on generalized estimating equations and it seems this could be valuable given objective.

How would I set up my data in order to assess the change in power in this subject group using a GEEGLM model in R?

Does anyone have a resource that can help me better understand GEEGLM and GEE?

I feel this may be a very suitable analysis approach given the longitudinal data we are able to collect in elite athlete groups where by definition (i.e. they are the elite) the sample sizes are very small yet detecting small meaningful changes are critical for success.

Thank you very much for any assistance you can provide.