A: As long as you have a relatively healthy body and joints, I think using something like ankle weights to strengthen the quads could be quite reasonable. Now, if you have significant knee or hip arthritis, you would obviously want to be guided by the amount of pain in the joints that the extra weight might cause. And if you were not particularly keen on using yet another extra item in your practice, rest assured that using your own body weight for resistance and strengthening can help to strengthen you quads, as well as longer hold with some of your standing poses. See Ram’s excellent post on Endurance Training for more information.
The ankle weights would be most likely to help build more quad strength when you take your leg into flexion a the hip joint, especially in poses like the standing pose Hasta Padangusthasana. In this pose, you start in Mountain pose and balance on one leg as you lift the other one up parallel with the floor or higher and use your same-side hand to hold that lifted foot (or use a strap if you are limited by tightness or leg/arm length challenges).
Another pose in which you could use the ankle weights is Reclining Leg Lifts, which in the yoga practice is called Urdhva Prasarita Padasana. I do these starting in Savasana, inhaling the arms overhead, then while exhaling the arms back to my sides simultaneously swinging one or both legs up to vertical. On my next inhale, I simultaneously lower the leg/legs back to the floor and take the arms back overhead, and finish by exhaling the arms to my sides. This can be repeated for a set of six or more. The ankle weights will make it a bit more challenging, and could potentially result in more muscle building in the quads.
Other postures that you could do that would not necessarily require or benefit from the ankle weights but would work to strengthen the quadraceps muscles in whole or part (since one of the four muscles that make up the quads flexes the hip joint, but all four extend the knee to straight), would include all of the straight leg standing poses done with attention to creating an isometric contraction of the muscles while in the held pose for a while. I usually shoot for about 90 seconds when working on muscle building and strengthening. You can actually check to see if you are engaging the muscles group by touching the front mid quad with your fingers to verify the muscle is firm and working. The straight leg poses poses I am referring to include Mountain, Triangle, Pyramid (Parsvottanasana), Half Moon pose (Arda Chandrasana), and Warrior 3 to name the most common.
You can get a slightly different effect of strengthening the quads by doing the standing poses where one or both knees are bent and once again working towards longer holds (gradually, of course, if you are starting out from a weaker places) of 90 seconds or so. My favorites are Powerful Pose (Utkatasana), Warrior 1 and 2 and Extended Side Angle pose.
Extended Side Angle Pose
I also like to do a wall version of Powerful Pose, with my back to the wall, feet about two feet from wall and a block in between the legs near the knee joint so the part of the quads towards the inside of the leg, the vastus medialis, will get stimulated to contract due to the block squeeze. (This part of the quads is notoriously weak in many people, even regular yoga practitioners and can cause kneecap-tracking problems that can lead to arthritis in some.) You then slide your torso and hips down the wall until your thighs are no lower than parallel with the floor, and your knees are positioned over your ankle joints, and you hold the pose for a bit. This pose is often more challenging to weaker quads, so start off holding for a few breaths and very gradually over the course of weeks or months, extend the time in the pose.So, with and/or without ankle weights, you can definitely improve quad strength with your yoga practice!
—Baxter
