Back to the daily grind. It was strongly tipped that our fearless leader would lock the entire state down again but instead he has mandated masks. If nothing else it will improve the appearance of the Victorian public. But I digress. The theme was power meters.
Functional Threshold Power measured on the bike is a handy way to adapt training intensity to a particular individual. Zones based on heart rate are another easily accessible method and a chest strap is less expensive than a power meter. Exercise physiologists have laboratories and all sorts of tech and therefore the means to make things way more complicated. By and large, though, the physiologists prefer a three zone system rather than five or seven,
You can find a good post (and podcast) by Dr Shawn Bearden on the topic <HERE>.
The zones or domains have nice practical names moderate, heavy and severe. The boundaries are only slightly fuzzy, rather than mostly arbitrary, and correspond with changes that can be demonstrated in the laboratory.
During moderate exercise oxygen consumption increases with work load. If you drew a graph it would be linear. At the same time lactate levels rise very little. As the intensity increases there comes a point where the slope of oxygen consumption increases and you enter the heavy zone. Round about the same point the lactate level heads gently upwards. FTP is close to the top of the heavy domain.
The moderate zone is easy, efficient and sustainable. The heavy zone is less efficient but still sustainable. Increase the load further and lactate begins to rise more rapidly, breathing becomes laboured and exhaustion beckons. The severe zone is inefficient and unsustainable but essential for a place on the podium.
The boundary between moderate and heavy sits at about 65 to 70% of FTP or at the top of zone 2 in the Coggan model that I discussed recently. Severe kicks in at the top of zone 4 (roughly).
Race pace for endurance events is in the heavy zone but should you train there? Proponents of polarised training say no. Training at moderate levels will build stamina and pace efficiently with the athlete adapting and recovering from fatigue optimally. Top this off with some training in the severe zone.
So perhaps the most important use of a power meter in training is to ensure your easy days are easy enough. You don’t need a power meter to tell you when you’re going flat out.