Sometimes as clinicians (including myself), we have a tendency to abandon simple exercises for more ‘fancy’ complicated but more ‘trendy’ ones.
Wall sits for example are an easy exercise requiring no equipment other than a wall. I have found it an effective exercise to prescribe to my 80-year-old or my 12-year-old patients whom I feel could use a bit of quads bulk!
The great thing about wall sits is that the patient is in full control of not producing any knee pain during the exercise.
Important Point #1: Do NOT let the knees pass over the ankles, it is the difference between having knee pain or no pain! Basically, the tibia should stay vertical the whole time.
Important Point #2: Flex the knees only to the point where there is absolutely no pain. There is no need to flex to 90deg, 45deg or 60deg of knee flexion is sufficient.
Important Point #3: Push the feet down hard as if standing up, to make a strong isometric quadriceps contraction. Hold for 10 seconds and repeat 5 times. Usually, by the 3rd repetition a burn in the quads is felt.
Important point #4: You may progress the exercise by using an unstable gym ball instead of a smooth wall (not recommended for the senior population!). You may also progress by holding 3kg dumbbells. You may ultimately progress by doing single-leg wall sits, holding for 10 seconds, repeat 5 times.