also, this page https://www.globaltimes.cn/content/803592.shtml says things like:
Why do they do that?
A: There is a very old Chinese belief that walking backwards for 100 steps is equal to walking forwards for 1,000 steps.
Chinese have been walking backwards to maintain good health since the ancient times.
Walking backwards exercises muscles that are not used in ordinary walking, especially in the back, waist, thighs, knees and lower legs.
Walking backwards is more tiring than walking forwards and in general it will give you a better cardio workout and will burn more calories.
According to traditional Chinese medicine (TCM), walking backwards is a good way to relax one's back muscles; it can relieve back pain and can also benefit the kidneys.
Elderly people have weaker muscles and backward walking can strengthen different muscles than walking forward does.
Backward walking is also said to be ideal for people who have knee problems or injuries as it puts less strain on and requires less range of motion from knee joints.
I never heard of this. The kneesovertoesguy mentions it in some of his videos on knee rehab / knee exercise, so I did a quick search.