Breathing Techniques to Enhance Performance: RMT and IHT


To enhance performance, the goal of all coaches and competitive athletes, new methods and new stressors must be applied throughout the training cycles. This article will address two specific types of breathing devices, applied similarly, but with different levels of physiological adaptations. Respiratory Muscle Therapy (RMT) is a method that trains breathing muscles to improve performance. Intermittent Hypoxic Training (IHT) provides brief doses of high altitude exposure to gain competitive advantage.


Respiratory Muscle Therapy First, a quick review of the respiratory muscles and how they function. At rest, the average person breathes 12-15 times per minute with a tidal volume (TV) of 0.5L of air per breath; thus moving 6L of air per minute (minute ventilation, 12 x 0.5). During exercise, breathing rates increase anywhere from 35-70 (for elite athletes) breaths per minute and TV rises to about 2-4L/minute increasing air movement to as high as 100- 300L/minute (dependent on size of person, sport and fitness level). All of this action puts a heavy burden on respiratory muscles. It is the job of the respiratory muscles to move all of this air during exercise. They are divided into two sets: inspiratory muscles (diaphragm, inspiratory intercostals, sternomastoids, scalenes) and expiratory muscles (abdominals, external obliques, expiratory intercostals). Inspiratory muscles work to increase the volume of the chest cavity by lifting the rib cage up and out – flattening and moving the diaphragm down


to expand the lungs. Expiratory muscles work to decrease thoracic volume by means of an elastic spring to return to normal – rib cage pushed down, diaphragm pushed up to its relaxed, dome shape. As the rate and depth of breathing increases during exercise, the majority of the work of breathing is undertaken by the inspiratory muscles. Expiratory muscles still work, mostly on the elastic return of energy provided by inspiratory muscles, but become more active as exercise intensity increases. The role of breathing muscles in performance in the past was largely ignored, assuming that the respiratory muscles are highly evolved and developed for their function and do not show fatigue during exercise. Research over the past 15 years has concluded a definite link between respiratory fatigue level and sport performance. During exercise, respiratory muscles


work at or close to the limits of fatigue. The work of breathing contributes to how hard exercise feels (RPE) and places demands on the circulatory system for blood flow to sustain muscular contraction to all working muscles. Research initially focused on respiratory muscle fatigue and demonstrated clear results in endurance sports: rowers, runners, cyclists, swimmers and triathletes, even in intermittent sports such as soccer. One study showed a decrease in run performance after a bout of heavy breathing where subjects pre-fatigued respiratory muscles, then ran a hard test; fatigued respiratory muscles limited performance. The runners ran slower because their breathing muscles were done. Respiratory muscles become fatigued during exercise and this is a performance limiter. As the respiratory muscles


take more stress and fatigue, this results in more fatigue in the working limb muscles. How does the work of breathing impact exercise tolerance and performance? In one study, researchers found that there is a preferential flow of blood to respiratory muscles and a decrease of blood flow to cycling leg muscles. The


By Melissa Mantak USA Triathlon Level III Certified Coach


stimulus for limb vasoconstriction is a cardiovascular reflex originating within the inspiratory muscles called the “inspiratory muscle metaboreflex.” This reflex is activated when metabolite accumulation within the inspiratory muscles stimulates afferent nerve fibers to increase their firing frequency. There are two important physiological


repercussions of inspiratory muscle fatigue (IMF):


1. IMF increases breathing and makes an athlete feel like they are working harder. 2. IMF causes blood flow restriction to the exercising limbs, impairing oxygen delivery and metabolite removal from the working muscles.


The underlying neural drive from the brain occurs as a whole system survival mechanism, breathing being an important factor to life. With the respiratory muscles fatigued, the working muscles will need to slow down or cease activity in order to give priority to respiration. A muscle derives its ability to produce


an external force from a neural drive. A strong muscle requires a lower neural drive to generate a given force because the force represents a smaller proportion of its maximum capacity. A fatigued muscle requires a higher neural drive to generate a given force because the force represents a higher proportion of its maximum capacity. Working to improve the fitness of respiratory muscles increases fatigue resistance of these muscles. Knowing that a set of muscles are fatiguing and limiting performance, training them to be stronger has the potential to improve performance and decrease the rate of perceived exertion.


Studies that assess the efficacy of RMT use test protocols of time to exhaustion, time trials and intermittent exercise. Strong evidence now exists that training respiratory muscles (think weight lifting for breathing muscles) improves endurance and strength therefore saving precious energy for working limb muscles. Several studies conclude that subjects ran or cycled further, faster and at higher power outputs. Research on swimming has been mixed. Some studies showed improvement in swim endurance,


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