The reason why the hind legs can't be straightened is that the whole body muscles and core strength of the exerciser are not strong enough, and the thigh muscles and calf muscles of the hind legs lack exercise.

In fact, any exercise will be effective as long as it persists, just as the ancients once said, "You can't make a thousand miles without accumulating steps", so as long as you follow Pamela for a period of time, it will definitely be effective. I also practiced with Pamela for a few days. Later, although I didn't persist for personal reasons, my body did undergo some subtle changes. Because the author insisted on doing sit-ups and some exercises at home every day to practice vest line during the epidemic, his physical fitness should also be improved. But when Pamela and I practiced stovepipe exercise, we gave up halfway because of the intensity. But later, the author found that the lines on the inner thigh were really obvious. It seems that practicing with Pamela is still effective!