In my toolbox article last month, I introduced the concept of using your Heart Rate Variability (HRV) – the difference in timing between subsequent heartbeats – to provide insight into how you are ...

How was Usain Bolt able to hit peak physical, technical, and mental form at 9.35 p.m. on 16 August 2009 at the World Athletics Championships in Berlin, when he ran the 100 meters in 9.58 seconds? Art?