When it comes to developing the legs, there are several effective exercises that target different muscle groups. For the vastus medialis, which is the inner part of the quadriceps, you can try leg extensions with the feet turned out or single leg exercises like step-ups, single leg squats, and Bulgarian split squats. These exercises require stabilization and can help activate the vastus medialis. Additionally, the Sissy squat with a deep stretch and squeezing the quads at the top can also contribute to development.
For the hamstrings, one of the best exercises is the stiff-legged deadlift. This exercise directly targets the hamstrings and can be highly effective. Other options include Romanian deadlifts and good mornings, although these exercises require proper form and technique.
When it comes to knee stability, squats are one of the best exercises if done properly. They strengthen the muscles around the knee and promote stability. Single leg exercises, such as single leg squats and single leg deadlifts,