Film yourself to improve
One of the most effective techniques I use to help my clients' training is filming them performing an exercise. It sounds ridiculously obvious but I only discovered how useful it was when I decided to film a client doing a core exercise so I could show him how it looked. It’s easy to miss things as a PT or if you’re training by yourself so filming yourself doing an exercise can highlight more subtle issues.
In this video example, my client performs a core exercise called the Dragonflag and it looks pretty good, but after watching the video with him the first thing I noticed was that his lower legs were at an angle. Not locking out the legs and maintaining a 'straight line' meant that his glutes and core weren’t properly engaged and helped explain why he struggled to get lower in that position.
If you’re serious about your training and want to improve, film yourself doing an exercise - you’ll learn a lot about how you move and you might spot something that you can change and improve