Kowloon Tsai Park Access

Yes, there are lockers, just bring your own padlock. They are located near the toilet block.
There is a good 500m rubber track running outside the athletic track fence which is good for speed work. I usually run there every Wednesday evening.

If I remember correctly, from Kowloon Tong side you can enter via the stairs next to the Rhenish Church Pang Hok Ko Memorial College at the end of Hereford Road. In addition to the track (which closes rather early in the evening) and the 500m jogging track outside the sports ground, you can run along the path around the parks and soccer fields which gives you some 1400m per lap. If you have trouble finding the locker, you can also try those at the swimming pool (if they allow you to use it).

Just forget the swimming pool. It closed from December to March each year. It does not have the padlock option and will not allow you to bring their key outside swimming pool. The changing room of tennis court can be trying as trennis players are not using the lockers at all. However, it is managed by the tennis association but not LCSD. The use of lockers to public are depends on the judgement of the management staff.

Hi Chin, thanks for the update.

There are also entrance to the park at La Salle Road and Inverness Road. Public lockers are located near the toilets and kiosk and you need to bring your own padlock.

I was able to find the entrance just fine. Thanks for the advice. And I can confirm that there are changing rooms and lockers outside where you bring your own padlock.