MODIFIED CO2 TOLERANCE TEST

The Modified CO2 Tolerance Test (also known as the Exhale Control & Hold Capacity Test) is a respiratory test developed by Dr. Justin Ternes. It is based on the well-known CO2 Tolerance Test created by Brian Mackenzie - with a few modifications aimed at improving the reliability and validity of the popular CO2 Tolerance Test.

Continue to see step-by-step instructions, a video tutorial, and a way to record your results.

SIMPLE INSTRUCTIONS
1. TAKE 3 DEEP BREATHS TO PREP
2. DEEP BREATH IN… START TIMER… EXHALE AS LONG AS YOU CAN
3. PUSH “LAP” WHEN YOU CAN’T EXHALE ANY MORE
4. HOLD YOUR BREATH AT THE BOTTOM AS LONG AS YOU CAN
5. STOP TIMER WHEN YOU NEED TO BREATHE
6. RECORD YOUR TIME

GOAL: SEE HOW LONG YOU CAN EXHALE OUT - THE LONGER THE BETTER

STEP-BY-STEP INSTRUCTIONS

1. TAKE 3 FULL BREATHS

This is the preparation to begin the exhale and hold. In through the nose, out through the mouth. Deep and effortful — all the way in, all the way out.

2. TAKE A FOURTH BREATH IN, START THE TIMER, AND BEGIN YOUR CONTROLLED EXHALE (AS LONG & SLOW AS POSSIBLE)

This is the most important component - the control of your exhale. Watch the video below to get more familiar with the technique.

THE EXHALE CONTROL TIPS

  • Hold your palm approx. 6 inches from your mouth and blow just barely enough to feel the stream of air on the palm of your hand.

  • Visualize blowing a candle just enough to make it flicker.

  • Exhale 90% to 100% out before you HOLD for the next part.



3. AT THE END OF YOUR EXHALE, PUSH “LAP” AND HOLD YOUR BREATH FOR AS LONG AS POSSIBLE

As soon as you are unable to continue the constant flow of air, HOLD your breath as long as you can.

4. STOP THE TIMER WHEN YOU NEED TO BREATHE

Challenge and encourage yourself to go as long as possible.

5. RECOVER & RECORD YOUR TIME

RECOVER your breath back to normal. RECORD your time.
(Exhale Time) + (Hold Time) = Total Time

Note any additional variables that may have contributed to the results:

Quality of sleep, fatigue, full or empty stomach, distracted, time of day, location, etc.

6) REPEAT the test 2 or 3 more times.

VIDEO INSTRUCTIONS FOR THE MODIFIED CO2 TOLERANCE TEST

1. Take 3 Full Breaths

2. Take a 4th Inhale

3. Start Timer & Begin Exhale

4. At End of Exhale, Hold

5. Press "Lap" to Record How Long You Can Hold

6. Stop Timer as Soon as You Need to Breathe

7. Recover and Record Your Time

8. Repeat

HOW TO INTERPRET YOUR RESULTS

Total Time // Ranking
Under 0:30 // Below Average
0:30 to 0:45 // Average
0:45 to 1:00 // Intermediate
1:00 to 1:15 // Advanced
1:15 to 1:30 // Very Advanced
Over 1:30 // Elite

Note: If you get below 30 seconds total, then you may be exhaling too hard and too quickly.

Repeat the test multiple times to get your average. 

What are we testing:

  • Lung capacity

  • Breath control

  • Nervous system stat

  • Stress levels

  • Skill & familiarity with the test

SHARE YOUR RESULTS!

Remember, your results will have three times:
(Exhale Time) + (Hold Time) = Total Time
Example: 33 second exhale, 22 second hold, 55 seconds total
0:33 / 0:22 = 0:55