Conducting Maximal and Submaximal Endurance Exercise Testing to Measure Physiological and Biological Responses to Acute Exercise in Humans

This method can help understand key questions in how exercise can be used to diagnose a variety of pathologies including exercise intolerance, ischemia, or subclinical dysfunctions not apparent at rest. The main advantage of this technique is that in a single test by evaluating an individual's response to exercise, you can determine if there are cardiac, pulmonary, and/or metabolic dysfunctions. Though this method can provide insight into understanding physiological responses to exercise, it can also be applied to understanding other parameters such as changes to the immune system, neurological functions and other cellular and biochemical processes.

Demonstrating the procedure will be Jesse Schwartz, a technician in the cardiopulmonary and performance laboratory. Begin the slow vital capacity maneuver by instructing the subject to sit with a straight back and feet flat on the floor with their legs uncrossed. Have the subject put his or her mouth around the mouthpiece and bite down.

Then fit the subject with a nose clip to seal off the nasal cavity. Start the maneuver on the software and instruct the subject to continue to breathe normally. Then ask the subject to inhale maximally and then exhale slowly until there is a plateau in the flow tracing.

At this point, instruct the subject to take a maximal breath in. Lastly, stop the measurement and allow the subject to release the mouthpiece. For the Forced Vital Capacity or FVC maneuver, instruct the subject to grasp the mouthpiece again while remaining in the same seated position.

Start the maneuver on the software and instruct the subject to continue to breathe normally. Ensure the subject has established a stable breathing pattern with a minimum of four tidal breaths. Then instruct the subject to inhale fully and rapidly and then to immediately exhale as quickly and forcefully as possible.

Lastly, ask the subject to continue to try and push all the air out of his or her lungs reaching a full exhalation while remaining in an upright posture until reaching a plateau for about five seconds. After this is complete, stop the maneuver on the software. For the last maneuver, Maximum Voluntary Ventilation or MVV, start it on the software to show the countdown bar indicating the number of breaths required before data collection begins.

With one breath to go in the countdown, direct the subject to start breathing deeply and rapidly through the mouthpiece for 12 seconds. Finally at the end of 12 seconds, instruct the subject to resume normal breathing and remove the mouthpiece and nose clip. If the subject feels lightheaded, encourage them to remain seated and to take slow deep breaths.

Begin by preparing the skin for the electrodes by shaving hair away from the electrode placement site if present. Rub the site with an alcohol pad and then with an abrasive pad to remove any dead skin cells. Then place electrodes for a 12-lead electrocardiogram.

For incremental maximal cycling test, start by fitting the subject to the bike by making sure the seat and handlebars are positioned comfortably. Wipe the subject's forehead with an alcohol wipe to remove any residue then secure a pulse oximeter to the forehead with a headband. Next, place the mouthpiece and nose clip on the subject.

Inform the subject that they will need to stay breathing through the mouthpiece for the entire duration of the test and breathe only through his or her mouth as the nose will be plugged with a nose clip. After two minutes of rest, begin data collection and instruct the subject to start pedaling at a rate between 60 and 80 RPMs. Have an assisting technician measure blood pressure one minute into each stage while a second technician assists with the test.

Then ask the subject to point on the Borg Grading of Perceived Exertion or RPE scale to rate his or her exertion level where six indicates that the exertion is perceived as easy and 20 indicates that the perceived exertion is at the hardest work they can imagine doing. Finally, continue the test until exhaustion of the subject then proceed to the recovery phase by dropping the resistance to the initial workload and instruct the subject to continue to cycle for another two minutes. For visit two, prepare the subject in the same manner as visit one.

Then begin data collection by instructing the subject to start pedaling at a pedal rate between 60 and 80 RPMs. From the 10 to 25-minute time point, instruct the subject to release the mouthpiece. Then ask the subject to re-grasp the mouthpiece from the 25th to 30th minute and during the last five minutes of the 45-minute test.

As the test continues, be sure to check that the VO2 hasn't increased significantly when the subject is back on the mouthpiece. Check that the subject's heart rate doesn't increase by more than five beats per minute and watch for any fatigue by the subject or that his or her RPE rating is rising. Finally, following 45 minutes, instruct the subject to complete a two-minute recovery period of easy pedaling.

Once complete, have the subject disembark the bike and draw five milliliters of venous blood. Results indicate that in a maximal exercise test where demand or exercise intensity is continually increasing with the increases in workload, the cardiopulmonary and metabolic response also continuously increase. In contrast, during a submaximal endurance exercise test, the demand is increased from that at rest but is raised to fixed exercise intensity.

As such, the cardiopulmonary response has an initial increase but then plateaus as the body adapts to meet the consistent demand. Further, in the maximal exercise test, RPE and respiratory exchange ratio will steadily increase until the end of the test whereas in a submaximal endurance exercise test, these parameters will plateau. While attempting this procedure, it's important to ask yourself, What data do you want to get from the exercise test?

And use this to design the exercise testing. The methodology demonstrated today was used to understand immunological changes in healthy individuals in the two different exercise regimens. Don't forget that what the patient does before they come to the test can affect the exercise testing results.

To improve consistency and reproducibility, restrict the use of stimulants, control food intake and exercise prior to testing. Also, keep testing conditions consistent and be cognizant of menstrual cycle phase when testing females.