At the end of the day, almost all cycling disciplines ultimately revolve around endurance, and that in turn relies on maximizing aerobic capacity and oxygen uptake. This explains the obsession with maximal oxygen uptake (VO2max) and lactate threshold measures. When you hear talk of power-to-weight ratio or sustained power, that also relies on aerobic capacity to generate the watts.
Improving aerobic capacity relies on many systems in your body (just ask my students preparing for the final exam in their exercise physiology course!). They range from improving the metabolic efficiency of your muscles, neural recruitment patterns, and the oxygen delivery to those muscles via the respiratory system (lungs) and cardiovascular system (heart).
Needless to say, ergogenic aids have cropped up to target many of these systems. This ranges from dietary supplements, muscle stimulators, altitude tents, all the way down the continuum towards infamous and illegal pharmaceuticals.
Every breath you take
Another recurring target for ergogenic aids is the respiratory system. Can we train our breathing to improve oxygen flow to our muscles or to become more efficient in our energy use? On the face of it, it certainly makes theoretical sense. Who wouldn't want more oxygen in the system? And considering that respiratory muscles can be responsible for nearly 10 percent of the total oxygen requirement during maximal exercise, a strong case can certainly be made for respiratory training.
With that in mind, a number of ergogenic aids have been marketed promising to improve the strength of your respiratory muscles. Scientific validation of these systems or respiratory training in general are relatively rare and somewhat inconclusive -- one potential culprit being the wide variation between training and testing protocol.
Study: Efficacy of respiratory training
A new study by Guenette et al., based at the University of British Columbia and published in the April 2006 issue of Applied Physiology, Nutrition and Metabolism, tries to shed some light on the efficacy of respiratory training using a popular system on the market and specifically focused on high-intensity cycling.
This system is touted as training, in an adjustable fashion, both the inspiratory AND expiratory muscles, and to work in a more advanced fashion than simply limiting airflow (i.e., breathing through a straw). Much to my annoyance, a quick review of the corporate Web site provided me with zero clues about what makes them different from a straw! I hate that!
The study utilized both males and females to see if there were sex-based effects (anecdotally, females tend to have lower lung volumes and may have greater tendency to be limited by respiratory factors). Interestingly, they chose untrained individuals to ensure that there were no confounding effects due to different training schedules. Participants completed a VO2max test initially, along with a battery of respiratory tests and measuring their maximal inspiratory pressure (MIP).
The actual cycling-related test consisted of a time trial to exhaustion (TTE) at 80 percent of the maximal wattage attained during the VO2max test. One of the downsides of using untrained subjects is the potential for high variability during the testing, but the authors did their best to minimize this.
Subjects performed a familiarization TTE test prior to the initial baseline TTE. Then after five weeks of progressive and monitored respiratory training using the device (progressive in that MIP was tested weekly and the respiratory training load adjusted as needed), subjects performed the TTE on two separate days, with the "best" time used for analysis. Subjects also performed a VO2max after the five weeks of training.
Summary of results
- Mean inspiratory pressure (MIP) increased by about 37 percent in the five weeks of training, with no differences between males and females.
- 100 percent compliance with the training protocol. None of the subjects increased their level of activity during the study.
- Time to exhaustion with the TTE at 80 percent VO2max was a mixed bag. On the one hand, there was no improvement when baseline was compared with either of the post-training testing days by themselves. However, when compared using the "best" of the two post-training days, the respiratory training prolonged time to exhaustion in both males (from 301 s to 353 s) and females (from 338 s to 416 s).
- No consistent changes in the cardioventilatory responses to the TTE post-training.
- No changes in VO2max post-training.
After reviewing this study and over the course of preparing this article, I'm unfortunately not much further ahead in my judgement about whether respiratory training, or this particular product, is a useful training idea or not. The results of this study are ambivalent and can be used by both its proponents and its detractors to advance their arguments.
- The biggest sticking point is the choice of using untrained non-cyclists. While the rationale for not wanting exercise and training to be a confounding factor sounds good on one level, this greatly increased the variability in the response, making meaningful comparisons and ultimately a clear answer difficult. That's a real shame, because the study was otherwise very well-designed and executed.
- It quickly drove me nuts that the corporate Web site had no meaningful information concerning how the system worked or was unique, despite their touting it as so much more advanced than other systems on the market.
Maybe the biggest lesson of all is that it's critical for all athletes to understand the strengths and limitations of various scientific designs in order to get beyond the techno-babble of training and ergogenic aids!
- Guenette JA, Martens AM, Lee AL, Tyler GD, Richards JC, Foster GE, Warburton DER, Sheel AW. Variable effects of respiratory muscle training on cycle exercise performance in men and women. Appl Physiol Nutr Metab 31: 159-166, 2006.
Stephen Cheung is an associate professor of Kinesiology at Dalhousie University in Halifax, Nova Scotia, Canada, and his athletic ability is beyond assistance from any ergogenic aid known to humans! Stephen's company, Podium Performance, also provides elite sport science and training support to provincial and national-level athletes in a number of sports. He can be reached for comments or coaching inquiries at firstname.lastname@example.org.