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 >

S-Index assessment improves inspiratory muscle performance

S-Index stands for Strength-Index. It is one of the POWERbreathe K-Series’ test modes. Its purpose is to calculate inspiratory muscle strength based upon peak inspiratory flow.

Peak Inspiratory Flow (PIF)

We can evaluate improvements in inspiratory muscle strength by monitoring changes in a person’s peak inspiratory flow.

Peak Inspiratory Flow is a measure which reflects the ability of the inspiratory muscles (the muscles we use to breathe in) to contract rapidly and overcome the inherent resistance and elastance of the respiratory system.

Another of the K-Series’ test modes is the measurement of maximal inspiratory pressure (MIP). In fact, MIP is the most common measure in use for gauging inspiratory muscle strength. It is used as a diagnostic tool and an independent predictor of all-cause mortality.

Purpose of study

Currently, the most common test for assessing inspiratory muscle performance is the maximum ‘quasi-static’ inspiratory pressure (PImax).

However, the K-Series’ S-Index test has since become available for ‘dynamically’ evaluating the maximum inspiratory pressure.

In fact, it is suggested that the S-Index might be more appropriate for measuring inspiratory muscle performance than PImax.

Therefore, this study investigates this premise. It also assesses its reliability and whether an inspiratory muscle warm-up effects strength—index assessment.

Measurement validity of the K-Series

There are, in fact, current studies that have independently verified the measurement validity of the K-Series. Consequently, findings from these previous studies demonstrate its accuracy to measure dynamic inspiratory muscle pressure 1,2.

Therefore, this study feels that a proper assessment and the reliability of the S-Index should be addressed. In particular, it investigates the variability in response to repeated measurements. Furthermore, it evaluates whether an inspiratory muscle warm-up effects strength-index assessment. It is investigating whether using strength-index assessment improves clinical outcomes by reducing the bias effect.

Reliable values of the S-Index

What this study demonstrates is that at least 8 inspiratory manoeuvres are necessary to reach maximum and reliable values of the S-Index. Moreover, it also shows that specific inspiratory muscle warm-up could improve inspiratory muscle performance.

The authors believe this to be the first study to evaluate S-Index reliability in healthy subjects. Furthermore, they believe it to be the first study to investigate the effect of inspiratory warm-up in strength-index assessment.

In conclusion, inspiratory muscle warm-up should be used for detecting the true maximum values of the S-Index to evaluate the performance of inspiratory muscles for any intervention.

Assessment of Maximum Dynamic Inspiratory Pressure >

References

  1. Measurement validity of an electronic inspiratory loading device during a loaded breathing task in patients with COPD
  2. Repeated-Sprint Cycling Does Not Induce Respiratory Muscle Fatigue in Active Adults: Measurements from The POWERbreathe Inspiratory Muscle Trainer 

Rugby & the Beneficial Effects of Inspiratory Muscle Training

The nature of the game of rugby involves high and low-intensity action. Also, the physical demands of the game are specific to each player’s positional role. However, despite the player’s position, all need to be aerobically fit. Each must also have a high lactate tolerance and be strong and powerful.

Challenges facing rugby players

Most of the game of rugby is sub-maximal. This means that the intensity at which the player performs increases at a steady rate. Furthermore, this sub-maximal exercise will only work the player up to 85% of their maximum heart rate.

However, integral to the game are intermittent sprints, tackling, scrums, rucks and mauls. These are supra-maximal. And it’s this part of the game that pushes players beyond their maximum limit. Consequently, breathing effort will be a challenge.

The pattern of exertion rugby has on players places extreme demands upon their breathing. This is because these activities are anaerobic and generate high levels of lactic acid. Furthermore, the lactic acid stimulates their breathing to increase. In addition, a unique feature of rugby is the involvement of high-intensity upper body activity. This can induce conflicting demands upon the breathing muscles, which as well as bringing about breathing, are also essential in activities that involve the upper body.

This 2018 study from Brazil reiterates the fact that the respiratory muscles need adequate work to maintain sustained effective breathing in the sport of rugby.

The scientific study

This scientific study set about analysing the effects of high-intensity inspiratory muscle training (IMT) in 20 amateur rugby players. These players are from the city of Uberaba, Minas Gerais, Brazil.

For the trial, the amateur players undergo a pulmonary function test, respiratory muscle strength and physical capacity assessment. Researchers then split them into two groups: the IMT group and the control group, each consisting of 10 players. The study has approval from the Research Ethics Committee of the Federal University of Triângulo Mineiro under protocol no. 2398.

Rugby training & conditioning for the trial

During the trial, players begin training with a warm-up by jogging for 5-minutes. They then perform dynamic stretching of the major muscle groups. Following this, the researchers have the players simulate specific moves applied to the game of rugby to improve its fundamentals. These include such moves as passing, blocking, feinting and collective strategic moves. Ultimately, the training session ends with stretching.

Players in the Inspiratory Muscle Training group perform three weekly sessions of an inspiratory muscle training programme, using the POWERbreathe Plus, for 12 consecutive weeks. These sessions are supervised by a physiotherapist and a physical education professional.

The IMT group protocol

This group protocol consists of:

  • 10 minutes’ stretching of the trunk muscles, upper and lower limbs
  • 10-minute inspiratory warm-up by performing a full and vigorous inspiration through the POWERbreathe Plus IMT device
  • A series of 30 repetitions using 80% of maximal inspiratory pressure using the POWERbreathe Plus IMT device. After the fourth training session, the level is increased.

The control group protocol

This group of 10 players perform the same protocol as above, except they do not perform the 30 repetitions of inspiratory muscle training using the POWERbreathe Plus.

Effects of high-intensity IMT in Rugby Players

Results show that the 12-week course of high-intensity POWERbreathe IMT provides significant increases in maximal voluntary ventilation (22%), maximum inspiratory pressure (38%), PEmax (32%), and distance travelled (13%) in the YoYo Test.

Also worthy of note is how physical capacity will be compromised if the respiratory system does not provide sufficient oxygen supply to satisfy the demands. Researchers explain that when the arrival of blood to the respiratory muscles decrease, it experiences fatigue and leads to lactic acid buildup. Consequently, this situation causes a decrease in the strength and resistance of the respiratory muscles.

Results of this trial suggest therefore that the POWERbreathe IMT training protocol provides beneficial, positive effects for rugby players.

The study

Effects of high-intensity Inspiratory Muscle Training in Rugby Players >

Tennis Players’ Endurance Improves after POWERbreathe IMT

New research shows tennis players’ endurance and strength improves after Inspiratory Muscle Training (IMT). The research from Pune, India, is in the International Journal of Current Research (February 2018).

What affects tennis performance

The main characteristics of this game are intense bouts of running, such as sprinting to reach a ball. Consequently, breathing is driven to its highest levels. And this induces extreme breathlessness. This affects performance.

In order to continue to play effectively while maintaining a high level of skill performance, breathing mustn’t hinder performance.

Breathing effort in tennis

Playing tennis involves using your breathing muscles in your torso to brace and twist during a racket stroke. Also, experienced players use their inflated lungs to brace the impact of the ball and racket. This helps them to control the release of air from their lungs and optimise the transmission of force. However, breathing muscle fatigue impairs this control. Thankfully though, breathing muscle strengthening training will improve this. Using a device that specifically trains the breathing muscles, the inspiratory muscles, is the easiest way of doing this. These are called Inspiratory Muscle Training (IMT) devices, such as POWERbreathe IMT. And training your breathing muscles to become stronger can help with a player’s postural control and movement too.

Research into players’ endurance

The research from Pune highlights the fact that tennis matches feature high-intensity, short- duration bouts of extreme activity with a short rest time. And it’s the competition of blood flow between the arms and legs and the breathing muscles which ultimately increases breathing fatigue.

For this study, researchers use the POWERbreathe KH1 Inspiratory Muscle Training (IMT) device to strengthen participants’ breathing muscles. Furthermore, each participant performed a prescribed protocol for using the device for five days over four weeks. Researchers were aiming to assess the effect of IMT on cardiovascular endurance in lawn tennis players.

Research findings

The findings of this latest research show there to be,

“significant improvement in cardiovascular endurance and strength in lawn tennis players after progressive inspiratory muscle training.”

How to improve tennis performance

POWERbreathe IMT specifically targets the breathing muscles, strengthening them by around 30-50%, significantly improving performance and helping to eliminate breathing fatigue. And these findings are a result of studies with tennis players who, after IMT, took less time to recover and were ready sprint maximally again more quickly.