Thanks for the input. The formula I found was (206.8-0.67*age), and the article claimed this was more accurate than the 220-age. My instinct is always to trust the data rather than some estimate, but I asked because the HRs I was seeing were higher than that formula would allow (i.e. higher than 206.8), so I figured something might be amiss.
I'll keep an eye on the numbers and set out to find my max.