To me it doesn’t matter if a client is inactive, active, in amazing shape, or an athlete. Everyone needs to be assessed, evaluated, and start a training program in a foundational stage. Of course, that doesn’t mean everyone starts with the same workout or same level on intensity. A foundational phase or workout does not mean it is easy or pointless. It simply means that together we work on some limitations or weaknesses in your body, movement, or current goals.
For one example lets say you are new to resistance training or new to physical activity. We cannot just start you out right in a workout that is 5 sets of 12 reps, getting close to failure, moving for 60 minutes, 2-3 times per week. No doubt we will get results and see changes in those first 4-6 weeks. But the likely hood of minor injuries in the joints is extremely high and we are also at an increased risk of serious injuries as well.
Another example is when someone is already active or training and they spend too much time in a specific phase of training geared towards their goals. Yes, the majority of their time should be spent in that training phase but they still need a well rounded program to prevent injuries.
No matter if you are new to training or been training for years time spent building a foundation or time spent revisiting your foundational weaknesses will result in better workouts and training during the high intensity phases yielding better healthier results as well.