Throwing a low kick mawashi geri?

[Wado Heretic]

Ōyama Masutatsu did modify the Mawashi Geri he was taught: making use of the instep, greater rotation of the hip, and the sinking the weight of the kicker into the target. As such, it does have a distinct character from the form as developed in the 30s-60s in University Association Shiai: the form of Mawashi Geri found in Shotokan and Nihon Karate-Do in general.

Similarly, most schools have developed the Mawashi Geri along different lines over time. Some schools favour connection with the shin, and others the instep. Some practice to come across on a horizontal plane, others up into the body, and others with the aforementioned downward motion.

Anyway, to return to your initial question: Yes, you can aim at the thigh or leg with a Classical mawashi Geri. However, it requires a downward motion to be effective and requires the Hip Flexibility and Strength I mentioned earlier. The opening of the hip is also a big tell to a trained opponent, and the commitment the kick requires makes it dangerous to use in a combat sport where one can clinch or go for a counter-punch to head. This is why it's not seen often, as it leaves the kicker more vulnerable than more conservative styles of low kick.

[immaterial]

and the sinking the weight of the kicker into the target. .

It might make some sense in terms of power generation ( I doubt it).. It's nevertheless poor posture to throw kicks from. Shotokan karatekas have the same ingrained habits passed on through generations. Compare it to the Koreans who throw them upright with better hip action..I believe it's largely due to superior flexibility, but also stronger concepts. On the other hand, I have only seen one TKDoin in my life with hands on par with the best Karatekas.. So, if you seek optimal TMA kicking mechanics, I would argue TKD is the way to go ... Optimal TMA punches - Karate. Optimal full contact kicks - probably Dutch Muay Thai.

These are my observations after many years in different worlds.

[Spartacus Maximus]

Most if not all Okinawan styles of karate have a mawashi geri that follows a small arc often targetting the thinner leg bone at point slightly above the ankle where there is less tissue and easier to break. Contact is made with the point where the foot joins the ankle, which is conditionned through training to withstand impact by kicking or controlled striking.

[conrad665]

In Shotokan, we never practice gedan mawashi geri. What we use as an attack below the belt is only ashi barai (what I am taught). In Ashihara Karate, however, gedan mawashi geri is effectively used. Another difference is in Shotokan, we use the upper part of the foot to kick, but in Ashihara karate, we hit with our shin bone, which increases the destructive power of the kick.