During COVID-19 pandemic beginner and junior athletes decreases their sports performance, because sports training sessions, practices, camps, and school have been cancelled/closed. So what are your suggestions?
A combination of exercises at the home, garden, and/or nature without contact with other people is desirable.
I have a very good experience with it myself. Gongfu, Yoga, or strengthening exercises can be done at home. Walking in the garden and running in nature.
Additionally, because it's kids, social media can be used to make competitions who make more push-ups and like. More fun for them. It will take their thinking into a certain direction.
Actually, a clever trainer can achieve quite a good result in health condition and stamina improvement in such situation.
For adults would be great Taiji Quan and Qi Gong for health exercises in lock down.