The incremental threshold test protocol we run here at Humon is as follows:
- Start cycling on a stationary cycle ergometer at a very low power (something that feels like minimal resistance, like 30 W) for 4 minutes
- Increase the wattage by 30 W every 4 minutes
- Cycle until you absolutely can't push any further (when you reach voluntary exhaustion)
- Start by running on a treadmill at a very slow pace for 3 minutes
- Increase the speed by 0.5 mph every 3 minutes
- Run until you can't push any further (when you reach exhaustion)
An example threshold test is shown in the screenshot below. When the athlete begins the test, he is cycling at low powers and during this time there is a mix of blue and green zones since his muscles are warming up. He reaches a plateau during the middle of the test (from minute 15-20) where the SmO2 doesn't change much and he is in a steady green zone. As the athlete continues to push himself beyond his threshold, the SmO2 starts dropping and the orange and red zones appear. When the athlete can no long push himself, he decreases the power and starts recovering. His threshold is considered to be when the red zone appears.