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Daniel Crumback


There are four potential limiters to performance:

  1. Cardiovascular,
  2. Musculoskeletal (MSK),
  3. Metabolic, and
  4. Respiratory.

Every athlete has at least one limiter. Our role as Sport Physiotherapists/Certified Exercise Physiologists who work with athletes is to identify limiters through testing and minimize or eliminate the limiter through training. Athletes with MSK limitations self-identify at our clinics every day. But what do we use to identify which of the other three limiters are affecting performance and should therefore be made a training priority? Can training programs be designed to focus on the specific systems?

The big idea

The respiratory system plays a major role in athletic performance, but is not usually considered a specific limiter that can be tested and trained. The current gold standard for cardiorespiratory testing is VO2max. Vollaard et al. suggest that it may be time for us to rethinkthe use of VO2max as a measure of aerobic performance: “VO2max and aerobic performance is [sic] associated with distinct and separate physiological and biochemical endpoints, suggesting that proposed models for the determinants of endurance performance may need to be revisited”.

In a standard VO2max, it seems that the most important indicators of a respiratory limitation are thrown out when the physiology stops and the math begins. The respiratory data used for the calculation of VO2max are the volume of air moved (ml/kg), and respiratory frequency (RF) – as a rapid increase in RF identifies the ‘lactate threshold’. But what about using the RF, tidal volume (TV), and minute volume (Ve) to measure respiratory performance in a sport specific-test against an athlete’s specific baseline – that is, forced vital capacity (FVC) and forced expiratory volume in one second (FEV1)? Could we focus training on improving a respiratory limitation? Would a change in respiratory effectiveness or efficiency result in improvements in performance?

My take on things…

I start with respiratory volume testing (FVC and FEV1 and FVC/FEV1) in order to establish an athlete-specific baseline. Thoracic and rib mobility is then assessed for limitation (SFMA), followed by a sport-specific VO2 test (our standard aerobic test that takes 50-60 minutes, as opposed to 8-12 minutes) along with metabolic measuresments using Moxy NIRS. I then analyse the respiratory frequencies used at each performance level during the test. Often, I find athletes breathing 40 breaths per minute at an easy pace, which has large metabolic ramifications. High breathing rates in an aerobic zone will cause hypocapnia and result in reduced tissue oxygenation secondary to:

  1. Vasoconstriction at the muscle (including heart and diaphragm), and
  2. Increased affinity of haemaglobin, which strongly bonds the O2, making O2 hard to offload at the mitochondria (Bohr Effect).

A high RF at low loads also means the athlete cannot increase to high RFs when needed at high intensity levels. A high RF at low loads may be a natural response (deconditioning), but in most cases, it is simply a learned neuromuscular technique that can be retrained with sport-specific coordination training – just as we would do for someone with any other neuromuscular limitation (technique/skill). In this case, the use of the Spirotiger device concentrating on learning how breathing at 20, 25, 30, and 35 respiration rate (RR) at rest, then during exercise, will assist the athlete in controlling their RR to maximize performance while under exercise stress.

Respiratory Limitation – Frequency (FVC 5.44 – FEV1 4.32)

Athletes that use less than 50% of their volume capacity (FVC) during exercise are also a common finding. By analysing the VO2 data throughout the stepped test at each performance level, we see the ’choices’ the athlete makes when under exercise stress. Commonly, we see a 6LFVC on testing, but the athlete only utilizes a TV of 3L during the VO2 test. This low TV results in a low Ve (depending on RF of course) which will  affect respiratory efficiency (Ve/VO2) and sport performance. This may be secondary to an endurance or strength issue.

With an endurance athlete, treatment would consist of medium volume breathing with lower reps/long duration workouts with a graduated load to improve the capacity of the athlete. For strength, we would concentrate on larger volumes with high repetitions/short duration workouts with longer work-to-rest ratios. Strength training would focus on increasing diaphragmatic strength, as well as thoracic and rib mobility. Spirotiger would be the tool of choice as athletes can workout for long periods without issue, whereas with other devices (e.g.PowerLung), workouts are limited to 10-30 breaths.

Respiratory Limitation – Volume (FVC6 5.89 – FEV1 4.36)

If a movement limitation or asymmetry is found during the assessment, a home program would be provided in conjunction with the training. I work with many cyclists, a number of whom have had rib or clavicular injuries secondary to crashes. We often forget to reestablish normal breathing capacity post MSK injuries which may affect lung function. Treatment (e.g. manual therapy/functional dry needling) will be offered if the athlete does not adapt within the first 2-4 weeks of movement and Spirotiger training.

In addition to the respiratory system’s primary task of moving air, it is one of the most important contributors to trunk stability. Trunk stability is vital to upper and lower quadrant strength and endurance, as well as overall sport efficiency. When the athlete has a respiratory limitation, the respiratory system will sacrifice its role as a stabilizer in order to continue to perform its primary role, and as a result, will negatively affect sport performance. A positive consequence of respiratory training under load is improved core strength and endurance.

An uncontrollable consequence of respiratory muscle fatigue is the effect of the “metaboreflex” on performance – a decrease in blood flow to working skeletal muscle resulting in increases in performance effort and muscle fatigue. The increase in muscle fatigue may play a pivotal role in determining exercise tolerance through a direct effect on muscle force output and a feedback effect on effort perception, causing reduced motor output to the working limb muscles.

Breathing exercises performed at rest and without load (e.g. crocodile breathing), while popular, will not affect athlete performance under exercise stress.

At a glance, here are key benefits to respiratory training:

  1. Substantial improvement in endurance and performance
  2. Improved peak performance under stress
  3. Shorter recovery times during and after competitions and training
  4. Improved endurance of the respiratory muscles
  5. Optimized oxygen supply to the skeletal muscles
  6. Faster return to homeostasis during and after stress (acidosis)
  7. Improved coordination capability of the respiratory system under stress
  8. Strengthening of the neck, abdomen and back muscles


Over the last 20 years, I have used VO2 (NOT VO2max), respiratory, and metabolic testing (topic for another day) to help many athletes, including athletes that have already maximized their other systems, make large gains in their performance  by identifying and minimizing their respiratory limitations. Even when it would appear that our patients (from the high performance athlete to the desk jockey) have reached their maximum MSK or cardiovascular recovery, it’s important to assess and address any limitations in respiratory function in order to optimize their recovery and full return to function

Dig Deeper

Quick reference sheet of the terms I’ve used above, along with their normal volumes for males and females.

Here are the links to the manufacturer websites for the equipment I mentioned in today’s rep:



Moxy Monitor

If you’re interested in reading more, these are the full citations for the papers I referred to above. All are open access:

McConnell AK & Romer LM. (2004). Respiratory muscle training in healthy humans: resolving the controversy. Int J Sports Med, 25: 284-293

Vollaard NBJ., Constantin-Teodosiu D., Fredriksson K., Rooyackers O., Jansson E., Greenhaff PL., Timmons JA., & Sundberg CJ. (2009). Systematic analysis of adaptations in aerobic capacity and submaximal energy metabolism provides a unique insight into determinants of human aerobic performance. J Appl Physiol, 106, 1479–1486.

Romer LM and Polkey MI. (2008). Exercise-induced respiratory muscle fatigue: implications for performance. J Appl Physiol,104(3):879-88



Could this approach work with other populations, such as patients with chronic respiratory conditions (e.g. COPD)?

How do you know when someone has a respiratory limitation in your practice?

Do you use breathing techniques to improve spinal stability?

Share your thoughts with me in the comments section below, via CPA’s Facebook page, or viaTwitter (hashtag #CPA30reps).

About Daniel Crumback 

Daniel is a sport physiotherapist, certified exercise physiologist and strength and conditioning specialist. He is the owner of Paragon Sport Performance – a performance testing and training company working with athletes of all levels. He has completed advanced training in FMS, SFMA, and functional dry needling. Daniel lectures regularly for Sport Physiotherapy Canada and has recently returned from China where he lectured on functional training at the Beijing Performance Summit. He is currently completing his masters at University of Alberta.