Nov 2-9 2016

Today we dig into questions I have had regarding a few aspects of my training in 2016 and we set the stage for a new approach to this podcast; using each episode to discuss the physiology and coaching aspects of a topic relevant to ultra running.

A couple of my own research articles were mentioned in the episode. They focused on the slow component of oxygen uptake kinetics. 

  1. THIS ONE showed that exercise intensities above the onset of plasma lactic acidosis (first lactate threshold, ventilatory threshold, gas exchange threshold, point at which lactate levels in the blood rise above resting values) there is an additional oxygen demand that arises after about three minutes into an interval. We knew about the phenomenon for years but this was the first definitive physiologic demonstration that it does not begin until later into an interval.
  2. THIS ONE showed that going from a light level of exercise, the rise in oxygen consumption at the start of an interval is faster than starting from rest. This means that you will reach V̇O2max earlier in the interval for the high intensity intervals we were discussing.

Other points that I made are from these articles:

  1. THIS ONE showed that prior exercise, like a prior interval, will cause a faster rate of increase in oxygen consumption in a subsequent interval. You’ll reach V̇O2max in a high-intensity interval sooner in the second interval, sooner still in the third. So, doing 5x3-minute intervals can accumulate time at V̇O2max even though very little time is spent at V̇O2max during the first and second intervals.
  2. THIS ONE showed that, after a high intensity interval (one that will cause you to reach V̇O2max), it may take as much as 45 minutes to recover fully so that the rise in V̇O2 at the start of an interval is the same as it was in the first interval. Rest periods shorter than this result in faster rise in V̇O2 at the start of the subsequent interval.
  3. You can start an interval fast enough that you reach V̇O2max in about 2-3 minutes but it is only sustainable for about that long. Or you can start at a slightly slower speed and you’ll reach V̇O2max after 4-6 minutes, but you’ll be able to keep running at V̇O2max for several minutes; the slowest you can go and still accomplish this is the minimum speed to elicit V̇O2max (minV̇O2max). THIS ARTICLE showed that the time to recover so that V̇O2 is back to baseline is shorter for minV̇O2max than for the higher speed that you only sustain for three minutes or so. Because minV̇O2max is a lower workrate, you recover faster even though you were consuming oxygen at a maximum rate for longer. The difference, however, is small. Even if we simply appreciate that the rates of recover are the same, it's remarkable that you can recover from minutes at V̇O2max as quickly as being at V̇O2max for only a short time when the former bout is at a well-chosen minV̇O2max. There is something very different about the energetic demands and the bioenergetics that support three-minute intervals vs eight-minute intervals even when both result in fatigue at V̇O2max. This study only evaluated those kinetics following a single interval…we don’t know what happens after multiple intervals of respective durations.
  4. THIS ONE showed that you can start off at a pace that will take you to V̇O2max quickly (like in three minutes), and you can also sustain running at V̇O2max if you just lower the pace a bit before you fatigue at the higher pace.