That would depend upon how one recorded the objective assessments in addition to what condition or or level of fitness the client is in. One would reassess using the same measures as one initially used.
If one used an OH squat that would be the reassessment after maybe three months. If it was a GXT then one would use a GXT.
Early on, have them enter an event of some sort. One that they are suited for, of course. For some this could be a 5k, for others it might be a sporting event. (I even pay the entry sometimes if they wear my brand) After some training and confidence building, I have them do it again to experience the difference their hard work is making. That’s MY favorite way anyhow.
I’ve actually created my own assessment for my clients. It consist of basic squat, plank, push up, body comp., and 10 yard shuttle run (30 seconds). These are the fundamental movements of exercise and allow me to asses their knowledge and movement of the exercises. During the exercises I evaluate their form and reps (optional), and count their reps during the shuttle run. I then test the same exercises 8 weeks later. This helps me see progress, and allows for clients to see progress as well.
My preferred method of evaluating their “overall” progress would be to simply retest/reassess the client with the same assessment tools that we initially used when they started. Another “less scientific” method that I LOVE to use with some of my clients – particularly the athletes, is a very subjective one – how do they feel? how do they perform? Because most athletes are very in tune with their bodies, I often simply watch their performance in competition, as well as ask them how they are feeling. A great way to teach some of my younger athletes to stay in tune with the ‘mind-body’ connection.