{"id":62,"date":"2015-01-29T16:21:20","date_gmt":"2015-01-29T16:21:20","guid":{"rendered":"http:\/\/stadiasportsmedicine.com\/info\/?p=62"},"modified":"2018-05-21T20:08:27","modified_gmt":"2018-05-21T20:08:27","slug":"improve-your-endurance-with-inspiratory-muscle-training","status":"publish","type":"post","link":"https:\/\/stadiasportsmedicine.com\/info\/2015\/improve-your-endurance-with-inspiratory-muscle-training\/","title":{"rendered":"Improve Your Endurance with Inspiratory Muscle Training"},"content":{"rendered":"

In most cases, an athlete\u2019s ability to exercise is limited by the heart\u2019s ability to pump blood to the muscles \u2013 not the lung\u2019s ability to deliver oxygen to the heart.\u00a0 Despite this, breathlessness can often limit exercise performance.<\/strong> This breathlessness doesn\u2019t relate to problems with air transport, but instead to fatigue of the respiratory muscles themselves \u2013 the diaphragm, intercostal muscles and the accessory muscles around the neck which assist with chest wall expansion during breathing.\u00a0 When we breathe, our airways generate airflow resistance that our breathing pump must work to overcome.\u00a0 The stronger the pump, the easier it is to overcome this air resistance and the easier the sensation of breathing is.<\/p>\n

The demands on the lungs increase significantly during exercise \u2013 particularly in late stages of exercise when the\"\" body is producing more lactic acid since lactic acid is converted to water and carbon dioxide \u2013 the latter being eliminated through ventilation.\u00a0 When we do exercise testing on patients in our office, it is not unusual to see an increase from about 7.5-10 liters of air breathed\/minute at rest, to 150-200 liters\/minute during maximal exercise.\u00a0 Rarely, elite athletes can increase their ventilation to 300 liters\/minute!\u00a0 Obviously, this places a significant stress on the muscles responsible for respiration, and these muscles are prone to fatigue just like other muscles in the body.\u00a0\u00a0 The harder the lungs work, the more blood flow they require, \u201crobbing\u201d blood from working limbs.\u00a0 It has been estimated that in late exercise, about 16% of oxygen consumption is used in order to power breathing.\u00a0 Research has shown that to effectively train respiratory muscles to better adapt to these higher ventilation levels, a training load that approximates ventilation during intense exercise needs to be imposed.\u00a0 Makes sense, doesn\u2019t it?<\/p>\n

So what does training of the respiratory muscles accomplish? <\/strong> First of all, strength training results in measurable structural changes.\u00a0 Ultrasound-based measurements of the diaphragm before and after 4-8 weeks of training show, on average, a 12% increase in thickness.\u00a0 After four and eight weeks of training, inspiratory muscle strength improved by 24% and 41%, respectively.\u00a0 Peak inspiratory flow rates and maximal power of the lungs have been shown to improve as well.<\/p>\n

But what does this mean for performance? <\/strong> Multiple studies have measured the effect of inspiratory muscle training (IMT) on performance in various endurance sports.\u00a0 Those in cycling have shown average improvements of 2.6-4.6% in time trial events ranging from 20 to 40 km in length.\u00a0 To translate this into real world numbers, I went to the 2012 results of the Hy-Vee Triathlon, men\u2019s elite division.\u00a0 Factoring in a 4.6% reduction in cycle time would have improved Aussie John Amberger\u2019s 6th<\/sup> place finishing time by 2 minutes and 41 seconds and put him into 1st<\/sup> place<\/strong>.<\/p>\n

Similar studies looking at changes in performance:\"\"<\/p>\n