As readers of our blogs will know, I am involved in research with colleagues at AUT in New Zealand on ‘durability’. We defined durability as the time of onset and magnitude of deterioration in physiological profiling characteristics – such as the ventilatory and lactate thresholds that mark the boundaries between intensity domains – over time during prolonged exercise (4). More simply, physiologically and perceptually, a 300 W effort when 20 min into a session is not the same as a 300 W effort when 200 min into a session. An athlete’s durability refers to how big the effect of those 200 min is.

We published a study last year that found an ~10% reduction in power output at the first ventilatory threshold (VT₁) following 150 min of moderate-intensity cycling (9). VT₁ is used as a marker of the transition between moderate and heavy intensity exercise. I use it as the upper boundary of “Zone 2”, and encourage my athletes to perform the bulk of...

In the triathlon and cycling communities, many of us have power meters on our bikes, or smart trainers at home. Power output data can be helpful in pacing efforts and tracking longer term progress. I myself programme many of my training sessions using power output – e.g. 4 x 40 min at 270 W for an Ironman workout – with the target number guided by the laboratory-based physiological profile of the athlete I am working with. For example, in the session above, the target power output is designed to be just above the first lactate threshold, in the so-called heavy intensity domain.

However, not all athletes have regular access to laboratory facilities for physiological profiling assessments and the determination of thresholds. For those athletes, power profiling represents an alternative, field-based method that can be used to provide anchor points in our training programming. Also, power profiling may be used to provide a still-elusive ‘durability’ metric. In...