Hypoxic Endurance Exercise Performance benefits from IMT

This new study (2019) looks into whether chronic IMT improves hypoxic endurance exercise performance.

Endurance exercise performance

The study, in the International Journal of Sports Physiology and Performance, is using a cycling time trial to measure endurance exercise performance. Endurance exercise is typically performed at submaximal intensity. The purpose of this is to estimate VO2max, or ‘aerobic fitness’. The measurement VO2max is the maximum amount of oxygen a person will consume during intense exercise. In fact, cycling time trials offer the ideal exercise to increase both heart rate and breathing. Similarly, so do running and swimming.

What is IMT?

IMT is a form of resistance training for the breathing muscles. The term IMT stands for inspiratory muscle training. The inspiratory muscles, the breathing muscles, are the ones that draw air into the lungs. The main inspiratory muscle is the diaphragm. Like any other group of muscles, the inspiratory muscles benefit from training too. Inspiratory muscle training, such as with POWERbreathe, provides the stimulus for that training. Following IMT, the breathing muscles adapt and become stronger after only a few weeks. This results in exercise feeling easier and an improvement therefore in performance.

Why IMT?

Although breathing comes naturally, some of the time it can feel like an effort. This may be due to the demand endurance exercise places on breathing. It may be due to a respiratory issue. Either way, it’s not uncommon for the respiratory muscles to fatigue, just like any other muscle.

If the respiratory muscles are weak from disease or exercise is overloading them, breathing demand will not be met. As a result, breathing will start to feel shallow and rapid. Sustaining this type of breathing is impossible. Furthermore, the more rapid the breathing, the more oxygen they require and the more carbon dioxide they produce. Consequently, oxygen is re-directed from the skeletal muscles, such as arms or legs, to the breathing muscles, where it is most needed. This results in fatigue of the skeletal muscles.

Inspiratory muscle training helps the body meet the needs of both the respiratory muscles and the skeletal muscles by improving their strength and stamina. The way IMT achieves this is by providing a resistance to breathe in against. POWERbreathe IMT is just like a ‘dumbbell for your diaphragm’.

Study results

Data from this recent study suggest that,

“performing 6 weeks of inspiratory muscle training may benefit hypoxic endurance exercise performance lasting 30-40 minutes.”

Exercise-Induced Diaphragmatic Fatigue In Healthy Humans

“In part of this study, twelve healthy subjects (33 +/- 3 years) with a variety of fitness levels exercised at 95 and 85% VO2, max to exhaustion.

Conclusion:

“Significant diaphragmatic fatigue is caused by the ventilatory requirements imposed by heavy endurance exercise in healthy persons with a variety of fitness levels. The magnitude of the fatigue and the likelihood of its occurrence increases as the relative intensity of the exercise exceeds 85% of VO2, max.”

Read Exercise-induced diaphragmatic fatigue in healthy humans >

Aerobic Fitness Effects On Exercise-Induced Low-Frequency Diaphragm Fatigue

“Bilateral phrenic nerve stimulation was used to compare the amount of exercise-induced diaphragm fatigue between two groups of healthy subjects, a high-fit group and a fit group.”

Conclusion:

“The high-fit subjects showed diaphragm fatigue as a result of heavy endurance exercise but were also partially protected from excessive fatigue, despite high ventilatory requirements, because their hyperventilatory response to endurance exercise was reduced, their diaphragm was utilized less in providing the total ventilatory response, and possibly their diaphragm aerobic capacity was greater.”

Read Aerobic fitness effects on exercise-induced low-frequency diaphragm fatigue >

Influence Of Environmental Temperature On Exercise-Induced Inspiratory Muscle Fatigue

“If blood is diverted away from the inspiratory muscles to the skin during exercise in the heat, exercise-induced inspiratory muscle fatigue might be exacerbated. This study hypothesised that prolonged heavy endurance exercise in the heat would impair exercise performance and exacerbate inspiratory muscle fatigue compared to exercise in a thermo-neutral environment.

Conclusion:

“This study concluded that heavy sustained exercise in the heat impaired subsequent time-trial performance but did not exacerbate inspiratory muscle fatigue in endurance-trained subjects.”

Read Influence of environmental temperature on exercise-induced inspiratory muscle fatigue >

Contribution Of Respiratory Muscle Blood Flow To Exercise-Induced Diaphragmatic Fatigue In Trained Cyclists

“This study investigated whether the greater degree of exercise-induced diaphragmatic fatigue previously reported in highly trained athletes in hypoxia (compared with normoxia) could have a contribution from limited respiratory muscle blood flow.”

Conclusion:

“When respiratory muscle energy requirement is not different between normoxia and hypoxia, diaphragmatic fatigue is greater in hypoxia as intercostal muscle blood flow is not increased (compared with normoxia) to compensate for the reduction in PaO2 , thus further compromising O2 supply to the respiratory muscles.”

Read Contribution of respiratory muscle blood flow to exercise-induced diaphragmatic fatigue in trained cyclists >