Respiration terminology and concepts
There are a lot of terms and acronyms in the video above, most of which are summarized here for easy reference.
Breathing frequency is how many breaths you take in one minute.
Ventilation is a rate that indicates how many liters of oxygen you move per minute.
Tidal volume measures the efficiency of your respiratory system by accounting for the amount of oxygen in milliliters per breath—i.e., ventilation divided by frequency.
Anatomical dead space is the volume of ventilated air that does not participate in gas exchange; while an athlete might take it in, they don’t use it.
Testing respiration at rest
One of the primary spirometry measurements is FVC (forced vital capacity), which is the greatest total amount of air you can forcefully breathe out after breathing in as deeply as possible. If your FVC is lower than expected, something is restricting your breathing.
The second key spirometry measurement is FEV1 (forced expiratory volume). This is the amount of air you can force out of your lungs in one second.
It can help your doctor evaluate the severity of your breathing issues. A FEV1 reading that’s lower than expected shows you might have a significant breathing obstruction. Your doctor will use your FEV1 measurement to grade the severity of breathing concerns.
FEV1 relative to FVC is ideally in the range of 78–82% at rest. If this number falls below this range, it can indicate a strength limiter. In more familiar physiological terms, FEV1 is similar to threshold on the bike. Ideally, you want to raise it as high as possible, closer to FVC, which is like your VO2max on the bike.
Testing respiration in training
For a cyclist who has never done respiration training, FEV1 as a percentage of tidal volume is typically 35–55%. The goal of respiration training is to get this number to 75–85%.
At the second ventilatory threshold (VT2), tidal volume drops off. This can be a coordination issue and a strength issue.
How to train respiration limiters
These two limiters are related to breathing frequency, but you can expect it to look a little different depending on the intensity of the effort.
1. Inefficient or high respiration rate
If you are not breathing deeply enough, you will be forced to take more breaths in one minute. By lowering your breathing frequency, you can move more gas (reducing your anatomical dead space) and extract more oxygen.
Train respiration endurance/tidal volume: Count your breath, working up to a point where you can breathe into your nose for 4 seconds, and breathe out in 2 seconds. Lower the rate of your breathing and increase the depth. Note that this breath work should not create stress.
2. High volume of anatomical dead space
Breathing frequency will escalate more quickly above VT2. Tidal volume will drop off and the anatomical dead space will increase, limiting the oxygen you can take in.
Train muscular strength and coordination: As breathing rate rises with intensity, try to expire more forcefully to allow tidal volume to remain higher. Practice breathing out a little quicker and more forcefully. This will give you a little more time to breathe in, keeping breathing frequency a bit lower, even in harder efforts. Note that respiration training works best when you focus first on endurance or tempo work.
Find out more about how heart rate factors into respiration and whether respiration could be a limiter for you. You can also get additional strategies for training your breathing frequency, without testing or additional equipment.
For a better understanding of the science behind respiration and performance, hear more from Steve Neal and Dr. Stephen Cheung in Fast Talk Episode 217, Understanding and Training Your Breathing.