Incremental exercise testing

“Incremental” means gradually increasing. The test starts at a low intensity, then increases speed, incline, resistance, or power output in stages at set intervals. As the workload rises, it allows observation of changes in responses such as oxygen uptake, heart rate, breathing, blood lactate, and rating of perceived exertion (how hard the exercise feels).

There are two types, distinguished by their stopping criteria: maximal tests, which continue until the person reaches their limit, and submaximal tests, which end when a predetermined target heart rate or intensity is reached. The approach is selected according to the purpose of the test and the person's health status.

The Bruce protocol is a well-known stepwise treadmill test. It increases both speed and incline every 3 minutes. A cycle ergometer does not involve weight-bearing, making it useful for people with knee or ankle discomfort, and allows resistance to be increased at a consistent rate. A treadmill has the advantage of resembling everyday movement because it involves walking and running.

1. Preparation — Before the test, resting heart rate and blood pressure are measured, and ECG electrodes are attached to the chest or a heart rate monitor strap is fitted. For detailed testing, the person wears a breathing mask, and a gas analyzer measures oxygen and carbon dioxide exchange. 2. Warm-up — Light-intensity exercise allows the body to adjust. 3. Increasing the workload — Exercise intensity increases one step at a time every few minutes. The tester periodically asks how hard the exercise feels. 4. Finishing — When the target criteria are reached or it becomes difficult to continue, the person signals to stop. Rather than stopping abruptly and standing still, they continue walking slowly as part of a cool-down.

The total time is usually around 10 minutes. Breathlessness and leg fatigue during the final stage are natural responses.

• For athletes to assess their current fitness and establish training intensity zones
• For members of the general public to check health-related fitness and exercise capacity
• To assess exercise responses during rehabilitation or cardiopulmonary rehabilitation
• To compare changes by repeating the test under the same conditions before and after training

The ventilatory threshold, lactate threshold, and heart rate zones identified through testing provide reference points for setting training intensity. Maximal oxygen uptake is the maximum amount of oxygen the body can take in and use, and is a key indicator of cardiorespiratory fitness. Research on predicting maximal oxygen uptake using cycling has also been ongoing for many years.

• Follow the pre-test instructions. Guidance on meal timing, caffeine intake, medication use, and clothing may vary by institution. Let the testing staff know in advance about any medications you regularly take.
• Bring comfortable exercise clothing and athletic shoes. For a treadmill test, running shoes you normally wear are a good choice.
• Take the test in a similar physical state each time. Results can vary depending on sleep, temperature, fatigue, and familiarity with the equipment, so when repeating the test, it is best to use the same time of day and maintain a similar physical condition whenever possible.
• Report any unusual symptoms immediately. If you experience chest pain, dizziness, or severe difficulty breathing, signal immediately and stop the test.

Although its name resembles progressive overload, it serves a different purpose. Incremental exercise testing increases workload every few minutes within a single test to observe responses, whereas progressive overload is a training principle that gradually increases training load over weeks to months to help the body adapt. The multistage fitness test (20m shuttle run), a simple field test, follows a similar principle of increasing speed at each stage.