How Rich Guys Stay Fit, Heart Rate Recovery, Resting Heart Rate Tracking, Heart Rate Variability, Cold Soak Temperatures, Little-Known Pre-Sleep Supplements & Much More With Keith Rabois.

The best single metric I use that I actually optimize my training for is what's known as a 2-minute recovery ... You take your body to as intense an exercise as you can tolerate and then stop, and then you see how fast and how strongly your heart rate recovers after 2 minutes. If you knew nothing else about somebody but what their 2-minute recovery was, you could predict a lot about their health, not just their fitness.

There are some people, though, that still eschew that idea and avoid the cold plunge post-workout because they've heard that it blunts the hormetic response to exercise ... But I looked into the data on this, and you have to get the muscle core temp. to drop by... 3+ degrees, and that takes a good 10+ minutes in pretty significant cold for that to happen.

I've always been pretty convinced that there's a strong connection between how your brain performs and how healthy your body is ... You can't be successful and thinking if your body isn't healthy and fit.

If you're going to track your sleep, it's really critical that you can engage in accurate sleep stage discrimination, and any wrist-worn device is not going to be very accurate for discriminating REM sleep vs. deep sleep.

When it comes to sleep, I just basically have this metric now... Pretty much anything that can be unplugged or placed in airplane mode, I'll unplug or place in airplane mode, and I found that to have a dramatic impact on sleep.

Resting heart rate is a pretty good measure of overall health. It's not perfect, but it's a pretty good proxy. I was reading research last week, in fact, that it might predict your likelihood of suffering from cancer.

Most of the research has shown that to get the benefits of cold, you got to be at 55 [degrees Fahrenheit] or lower.