Open problems · P8
Slowing near a measurable edge: exercise intensity
Oxygen uptake and blood lactate settle quickly at moderate exercise intensity, only after a delay at heavy intensity, and not at all above critical power. Is the delay critical slowing of one recovery process as the edge approaches, or a second, slower process (the oxygen-uptake slow component) switching on?
Why it matters
Critical power is one of the few edges in human physiology that can be located in one person and approached in controlled steps. If recovery time lengthens as it nears, the mountainside's central prediction can be tested in people directly, rather than through group averages in cohorts.
What exists
- The physiology of the exercise intensity domains (Jones et al., Physiological Reports 2019).
- The mountainside model and its predicted recovery-time curve (Mountainside).
- Breath-by-breath gas exchange and heart-rate recording, standard in exercise laboratories.
A first step
Locate critical power in each participant, then run graded constant-work-rate bouts below and above it and measure oxygen-uptake and heart-rate recovery kinetics after every bout; within the bouts below critical power, add identical small, brief steps in work rate and time the return from each. Work rate plays the part of the dilution rate in the yeast experiments on the mountainside page: the edge is located per person and recovery is measured at known distances from it. Critical slowing predicts a return time that is flat at low intensity and rises steeply only close to critical power; a second process predicts a change in the shape of the return, not just its speed.