Respiratory Muscle-Induced Metaboreflex

A recent research paper in Experimental Physiology looks into the effect of an increase in inspiratory muscle work on blood flow to inactive and active limbs. It addresses the process of metaboreflex.

What is metaboreflex?

Metaboreflex is where the body restricts blood flow to the limbs when the breathing muscles fatigue. The body will do this to ensure the role of breathing continues. This is because breathing is crucial to survival. Therefore, when the body experiences a conflict between breathing and moving, breathing wins out.

How does metaboreflex work?

As soon as the body senses a conflict between breathing and extreme activity, it will redirect blood flow to the breathing muscles, for survival. In so doing, blood flow to the exercising limbs shuts down, allowing the diaphragm a chance to recover. What this tells us is that the stronger the diaphragm is, the faster it will recover. Consequently, stronger breathing muscles will, in turn, result in a better blood supply to your working limbs. This will result in a better sports performance.

These YouTube videos from breathing expert James Fletcher, clearly demonstrate the metaboreflex.

Part 1

Part 2

Study results

When exercising, the amount of energy consumed by the working muscles can be high and prolonged. Blood flow to these working muscles needs to be matched. The results of this study suggest that the control of blood redistribution to the working muscles is facilitated, in part, by respiratory muscle-induced metaboreflex.

Delaying the onset of metaboreflex

Improving the strength of your breathing muscles will help to delay the onset of the metaboreflex for the diaphragm. A scientifically proven way of doing this is with Inspiratory Muscle Training (IMT). In fact, there are other studies showing IMT to be beneficial too.

This award-winning research, awarded by the European College of Sport Science (ECSS), also suggests the potential role of IMT to reduce inspiratory muscle metaboreflex.

Another study suggests respiratory muscle training could enhance sports performance by delaying this process.

Finally, there is a study by Germain Fernandez Monterrubio, Bachelor of Science in Physical Activity and Sport, in which he finds how respiratory muscle fatigue can affect exercise tolerance on a pulmonary level, as well as, a muscular level.

Effect of increased inspiratory muscle work on blood flow to inactive and active limbs during submaximal dynamic exercise >

Effects of work of breathing on blood flow during exercise

Published in Experimental Physiology this research sought to simultaneously assess leg and respiratory muscle blood flow during intense exercise while manipulating the work of breathing (WOB).

Researchers from Canada & Brazil hypothesised:

  1. Increasing the work of breathing would increase respiratory muscle blood flow and decrease leg blood flow.
  2. Decreasing the work of breathing would decrease respiratory muscle blood flow and increase leg blood flow.

The work of breathing (WOB)

Changes in work of breathing are significantly and positively related to changes in respiratory muscle blood flow. By which it shows that increasing the work of breathing increases blood flow.

On the other hand, changes in work of breathing are inversely related to changes in locomotor blood flow. So decreasing the work of breathing increases locomotor blood flow.

Study findings

Therefore findings from the study support the concept that respiratory muscle work significantly influences the distribution of blood flow to both respiratory and locomotor muscles.

The study

Effects of respiratory muscle work on respiratory and locomotor blood flow during exercise >

Athletes Do Not Condition Inspired Air More Effectively than Non-athletes

There is a study that aims to assess athletes’ ability to warm and humidify inspired air. This study is published in Medicine and Science in Sports and Exercise. It is called, Athletes do not condition inspired air more effectively than non-athletes during hyperpnea.

Endurance athletes’ inspired air

Airway disease is more prevalent in endurance athletes. This is possible because they need to adapt their breathing to cope with large volumes of inspired air. And they need to inspire large volumes of air because of the intense exercise they perform. But the environment they train in may also be relevant.

Study method

The study measures the difference between each athlete’s inhaled and exhaled air temperature. It did this during and after a Eucapnic Voluntary Hyperpnea test (EVH). This is the test that is used to diagnose exercise-induced asthma or exercise-induced bronchospasm. It is a 6 minute test during which the athlete breathes a cold, dry gas at very high ventilation rates.

All 23 athletes in the study attend a laboratory on three occasions. Two of these occasions are for baseline measurements and information. The third is to perform a modified EVH test. This is to measure their inspired and expired air temperatures.

No evidence of improved capacity to condition inspired air

The test results show no evidence of improved capacity to condition inspired air. And by ‘conditioned’ air the study means the athlete’s ability to warm and humidify inspired air. If the study did find evidence, this could suggest an increased bronchial blood flow or another adaptive mechanism. Bronchial blood flow supplies nutrients and oxygen to the cells that constitute the lungs, as well as carrying waste products away from them. Therefore the absence of an adaptive mechanism could contribute to airway damage observed in endurance athletes. This may be that colder but mainly dryer air is penetrating deeper in the lung.

Strategies to reduce impact on airway injury

A pre-exercise warm-up is well known to reduce the severity of exercise-induced bronchospasm and exercise-induced asthma. It is thought the reason for this is because of an increase in bronchial blood flow. A warm-up involves performing the athlete’s activity at a slower pace and reduced intensity. It gradually raises the body temperature. Furthermore it increases blood flow to the muscles.

An inspiratory warm-up

It is also beneficial to warm-up the breathing muscles. A scientifically proven way of doing this is with Inspiratory Muscle Training (IMT). POWERbreathe is an IMT device that is quick and easy to use. POWERbreathe IMT is performed as part of an athlete’s daily training. But research and trials have also shown it to be beneficial for an inspiratory warm-up. This means simply reducing the breathing load on the POWERbreathe IMT device to a lower setting. Better still the POWERbreathe K3, K4 and K5 with Breathe-Link Live Feedback Software feature an automatic warm-up mode. This automatically sets the optimal resistance for an inspiratory muscle warm-up.

Effects of Inspiratory Muscle Training on Respiratory Muscle Mechanics and Haemodynamics in Healthy Adults

“The effects of inspiratory muscle training (IMT) remain controversial. Many studies have examined the effect IMT has on exercise performance, but any changes to the body that come from IMT have yet to be looked at.

This study will look at how someone breathes can change after IMT. Understanding how IMT changes the body can help us use IMT in different treatments.”

Go to Effects of Inspiratory Muscle Training on Respiratory Muscle Mechanics and Haemodynamics in Healthy Adults >

 

Respiratory Muscles and Inspiratory Muscle Training

Clinical trial: Effects of Inspiratory Muscle Training on Respiratory Muscle Mechanics and Haemodynamics in Healthy Adults

The purpose of this clinical trial is to study any changes to the body that come from Inspiratory Muscle Training (IMT), looking at how someone breathes may change after IMT, and how this could help with using IMT in different treatments.

Sponsored by the University of British Columbia, this study is currently recruiting participants aged 19 – 39 years.

Read the clinical trial, Effects of Inspiratory Muscle Training on Respiratory Muscle Mechanics and Haemodynamics in Healthy Adults

Check out more Inspiratory Muscle Training Research here >

Discover POWERbreathe used in Research here >