In part 1 on respiratory muscle training (RMT), it was revealed that RMT in the form of inspiratory muscle training (IMT) does indeed improve athletic performance across a wide range of sports. Part 2 will cover the mechanisms by which RMT works, the specificity of inhalations when performing IMT, using IMT before a race, and what we don't know about RMT.
How RMT Works
The proposed mechanisms by which IMT improves performance are multiple:
Reduction of perceived exertion. When breathing becomes very labored at the end of races or training sessions, respiratory training, decreases the perception of hard breathing.
Attenuation of the metaboreflex. The cost of supplying blood supply and oxygen to the breathing muscles during maximum exercise can use up to 16% of cardiac output (8). The elevated breathing causes more adrenaline to be released which causes LESS blood flow to working muscles (the adrenaline causes peripheral vasoconstriction). To keep blood flow to the breathing muscles, and continue breathing, the body will essentially redirect bloodflow so that the intercostal and diaphragm muscles can continue lung function. This phenomenon is termed the metaboreflex. IMT has been shown to attenuate the metaboreflex thereby keeping blood flow to the working muscles and maintain nominal breathing.
IMT improves respiratory muscle economy, the work of breathing. The energy cost of breathing hard and intense is reduced.
Respiratory muscle endurance. The ability to breathe for long periods of time is increased.
These four primary reasons show how RMT works to improve performance in a wide variety of sports.
Specificity of Training
The systematic reviews (1, 2, 3, 4) inform us to breathe according to your sport. If your race or training requires you to breathe fast and shallow such as swim races of 100 or 200 yards/meters, then your inhalations should mimic those considerations. Breathe quickly and forcefully in and then relax the exhalations (so you don't pass out).
If your race is longer, 10 minutes to hours, then mimic those aspects of breathing. For example, when running it is common to do 2 inhalations in (one with each step) and 2 exhalations out (again, one with each step). Your IMT should include the same rhythm.
Generally, try to match the breathing conditions of your sport when doing RMT.
Using RMT (IMT) for Warm-Up
In a study published in 2014 (6), 9 male and 6 female elite British swimmers performed 2 sets of 30 breaths of IMT before their specific 100m strokes (fly, back, breast, free). The IMT intensity used was only at 40% of maximum inhalation to prevent undue fatigue before racing. Times improved by 0.6sec on average.
It's assumed that lung muscles are warmed up before a race. Perhaps not. It seems we can warm-up our lung muscles further by using RMT. For something so easy to do, IMT before a race could be worthwhile addition to your pre-race routine.
What Is the Current State of RMT?
Here are what researchers have yet to uncover with IMT (2).
Should IMT be incorporated before, during, or after training sessions? I can imagine some interesting sets using IMT during a workout.
Should IMT be periodized? Only at the beginning of the season, the end? Year-round? Perhaps a year-round three or four-week RMT periodization followed by one week of no RMT seems reasonable.
Much research still needs to be done in the area of respiratory muscle training.
Part 3 will discuss exactly how to perform inspirations and for how long...
Shei, R. J. (2018). Recent advancements in our understanding of the ergogenic effect of respiratory muscle training in healthy humans: A systematic review. The Journal of Strength & Conditioning Research, 32(9), 2665-2676.
Karsten, M., Ribeiro, G. S., Esquivel, M. S., & Matte, D. L. (2018). The effects of inspiratory muscle training with linear workload devices on the sports performance and cardiopulmonary function of athletes: A systematic review and meta-analysis. Physical Therapy in Sport.
Gualdi, L. P., Sales, A. T., Fregonezi, G., Ramsook, A., Guenette, J., Lima, I., & Reid, D. (2015). Respiratory muscle endurance after resiratory muscle training in athletes and non-athletes: A systematic review and meta-analysis.
Menzes KKP, Nascimento LR, Avelino PR, Polese JC, Salmela LFT (2018). A Review on Respiratory Muscle Training Devices . J Pulm Respir Med 8: 451. doi: 10.4172/2161-105X.1000451
Leddy, J. J., Limprasertkul, A., Patel, S., Modlich, F., Buyea, C., Pendergast, D. R., & Lundgren, C. E. (2007). Isocapnic hyperpnea training improves performance in competitive male runners. European journal of applied physiology, 99(6), 665-676.
Wilson, E. E., McKeever, T. M., Lobb, C., Sherriff, T., Gupta, L., Hearson, G., ... & Shaw, D. E. (2014). Respiratory muscle specific warm-up and elite swimming performance. Br J Sports Med, 48(9), 789-791.
Tong, T. K., Fu, F. H., Chung, P. K., Eston, R., Lu, K., Quach, B., ... & So, R. (2008). The effect of inspiratory muscle training on high-intensity, intermittent running performance to exhaustion. Applied physiology, nutrition, and metabolism, 33(4), 671-681.
Seals, D. R. (2001). Robin Hood for the lungs? A respiratory metaboreflex that ‘steals’ blood flow from locomotor muscles. The Journal of physiology, 537(1), 2-2.