Stretching your heel and calf targets the lower leg muscles, specifically the calf muscles.
It is an excellent exercise to strengthen the quadriceps and hamstrings without straining the knees.
Rather than using a machine, doing this with your body weight helps to keep pressure off your knees.
Straight leg raise makes the quadriceps and hip muscles strong.
This exercise targets the quadriceps and the muscles in front of the thighs. This stretch improves the flexibility of hip flexors and quadricep muscles.