8. TRAINING ZONES CHANGE DURING LONG RIDES

Photo by Markus Spiske on Unsplash

In a previous post, we saw that durability ( the ability to decrease as less as possible performance during prolonged exercise) is an additional independent parameter determining endurance performance, as it isn’t related to traditional physiological parameters like VO2max or power at ventilatory thresholds/FTP.

A higher VO2max or FTP doesn’t necessarily mean a higher durability.

In addition to performance, the durability concept could be applied also to training zones. Training zones should be divided by specific physiological thresholds like ventilatory thresholds or critical power, given that physiological strain and recovery differ if trespassing or not these benchmarks. (1)

For example, using a classic 5 or 7 zones model, the benchmarks should be placed as following:

• Zone 2-Zone 3 benchmark: around the first ventilatory/lactate threshold;

• Zone 4-Zone 5 benchmark: around the second ventilatory/lactate threshold or critical power;

During traditional tests, physiological thresholds are calculated at rested state after a 5-30 min warm-up. However, during long training sessions, it is common to perceive a given power output harder in the second half of the ride compared to the first one.

Is it only a perception, or even physiological thresholds (and so training zones) change during prolonged exercise?

Are training zones stable or do they move during prolonged exercise?

A study published by Stevenson and Colleagues (Auckland University of Technology, New Zealand) on European Journal of Applied Physiology in 2022 tried to answer this question. (2)

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WHAT DID THEY DO?

• They recruited 14 (13 male, 1 female) trained cyclists/triathletes (avg VO2max: ~60).

• During a single lab visit:

  • They first performed a step test around VT1 to calculate VT1-rest.

  • After 2 hours of cycling at 90% of VT1 power calculated at rest, the same step test was repeated to calculate VT1 after 2 hours of cycling (VT1-2h).

The goal was to see if power and heart rate at VT1 (and so training zones) change or not during prolonged exercise.

Simplified representation of the study design. Image adapted from Stevenson et al. (2022). (2)

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WHAT DID THEY FOUND?