the athlete’s training exercises and "formuli"

[sitifan]

It’s rather like being an athlete. We know the importance of training. We can read about the athlete’s training exercises and formuli. (My bold.)
Source: page 161. https://www.amazon.com/-/zh_TW/Brian-Mills/dp/0860653854

What does the word "formuli" mean?

 

[emsr2d2]

I think the writer incorrectly thought it was the plural of "formula". However, it should be either "formulae" or "formulas".