Breathing and Swimmers' Posture

Breathing is obviously important to swimming.  We've discussed breathing multiple times on this site with topics from breathing patternsArmpit breathingSwimmer's Lung Capacity, and Inspiratory Muscle Fatigue.  Most recently, Dr. Mitch Lomax discussed his recent findings in this area noting that "[Inspiratory Muscle Fatigue] occurs during swimming, even in very well trained swimmers. It can negatively affect stroke characteristics, and has the potential to speed up the occurrence limb muscle fatigue. The good news is that we can do something about it."

One concept that we've also addressed has been breathing’s effect on spinal mechanics.  Breathing is often overlooked as a movement pattern, but plays a vital role in shaping movement.  Virtually everything we do involves breathing, whether we realize it or not.  As Hodges (2001) notes, “[r]espiratory activity of the diaphragm and other respiratory muscles is normally coordinated with their other functions, such as for postural control of the trunk when the limbs move.”

Postural abnormalities such as kyphosis (hunchback) and lordosis (swayback) are commonly associated with shoulder and back problems in swimming.  It has been well established that hyperactive upper trapezius activity, shortness of the pectoralis minor, and weakness in the lower trapezius are linked to shoulder maladies and to thoracic kyphosis.  Given what we know about respiratory mechanics, might breathing be an avenue to effect change in this area?    


One study to explore the link between breathing, posture and movement involved swimmers.  Obayashi (2012) studied twenty six healthy swimmers evenly divided into an exercise group and a control group.  Authors sought to determine the effect that breathing exercises could have on spinal curvature of the thoracic and lumbar spines.  The exercise group performed respiratory muscle exercises ten minutes per day three times per week over four weeks.  The control group only performed their normal swim training.  Findings included:
  • Significant a decrease in the thoracic kyphosis by 13.1% in the exercise group  (less hunchback)
  • Lumbar lordosis reduced by 17.7%  in the exercise group (less swayback)
  • Compared to the non-exercise group, the exercise group had 8.6% less thoracic curve and 20.9% less lumbar curvature than the control group
  • forced vital capacity and forced expiratory volume in 1.0 s were significantly increased after four weeks in the exercise group
Authors offered the following explanation for their findings:
"[A] rise in intra-abdominal pressure presses the rib cage upward and effectively allows the extension of the thoracic vertebrae.  In addition, we attribute the decrease of thoracic curvatures to a stretching effect on the thorax. In a previous study, Izumizaki et al reported that thoracic capacity and rib-cage movement were changed by thixotropy, which is the exercise of maximal expiration from maximum inspiration. The stiffness of the rib cage leads to thoracic kyphosis.  In this study, repetitive deep breathing resolved the stiffness of the rib cage and straightened thoracic kyphosis. This process may be responsible for altering the spinal curvature."

Similarly, we wrote last year, "The rib cage is more than a passive protector of internal organs and a mere puppet of respiration. Though it’s not a body part amenable to cueing in the water, better rib cage function can free the swimmer of restrictions. Most importantly, optimal rib cage function via breathing, posture, and movement can improve shoulder health." (See, Forgotten Rib Cage)  In sum, consider not just the shoulder itself, but the structure and function of all areas around it.  Breathing is a key part of that consideration.     

CONCLUSION
The findings in this study make intuitive sense to anyone who observes breathing in a training environment.  Yet training the breath is often seen as a wasted activity more properly reserved for quiet meditation and not of sufficient importance for “serious” dryland training.  

Even if you don’t set aside time for breathing exercises, attention to respiratory mechanics should be a part of any dryland program to optimize spinal function and develop healthy shoulders.  Though more study is needed in this area, this research does lend support to the connection between respiration and shoulder mechanics in competitive swimmers.    

REFERENCES
  1. Hodges PW, Heijnen I, Gandevia SC.J Physiol. 2001 Dec 15;537(Pt 3):999-1008.
  2. Postural activity of the diaphragm is reduced in humans when respiratory demand increases.
  3. Ludewig PMReynolds JF.  The association of scapular kinematics and glenohumeral joint pathologies.  J Orthop Sports Phys Ther. 2009 Feb;39(2):90-104. doi: 10.2519/jospt.2009.2808.
  4. Obayashi HUrabe YYamanaka YOkuma RJ Sport Rehabil. 2012 Feb;21(1):63-8. Epub 2011 Nov 15.  Effects of respiratory-muscle exercise on spinal curvature.
  5. Izumizaki M, Ohshima Y, Iwase M, Homma I. Chest wall motion after thixotropy conditioning of inspiratory muscles in healthy humans. J Physiol Sci. 2006;56:433–440.
By Allan Phillips. Allan and his wife Katherine are heavily involved in the strength and conditioning community, for more information refer to Pike Athletics.

Friday Interview: Dr. Mitch Lomax

1. Please introduce yourself to the readers (how you started in the profession, education, credentials, expertise, etc) I’m a Sport and Exercise Scientist and a Senior Lecturer in Sport and Exercise Physiology at the University of Portsmouth, UK. I gained both my PhD (2007) and MSc (with distinction, 2001) from Brunel University, UK, and my BSc (Hon) from Luton University (1998). I’m an accredited Sport and Exercise Scientist with the British Association of Sport and Exercise Sciences (BASES), and an advisor to both the Amateur Swimming Association of England and the English pistol Shooting squad.

Most of my childhood was either spent in or around water and when I stopped competing I began coaching. The unique environment of swimming and its effects on the body have always interested me. For example, swimmers must breathe in (and hence expand the chest) against the hydrostatic pressure of water, which is greater than that of air. This increase in pressure has a number of negative effects on the body and coupled with a horizontal position it increases the work of breathing. On top of this breathing must be coordinated with stroke cycle and therefore cannot occur truly ad libitum.

When I first started investigating the breathing muscle demands of swimming I was amazed that the occurrence and consequences of breathing muscle fatigue in swimming had been overlooked. The rest as they say is history.

2. You recently published a couple of articles related to swimming, could you briefly explain the practical results? Most of my work focuses on the occurrence and consequences of inspiratory muscle fatigue (otherwise known as IMF) in swimming. We have found that IMF occurs in all swimming strokes and that being very fit does not prevent it. Also, swimmers do not need to be swimming flat out for IMF to develop. For example, swimming above critical velocity (or critical swimming speed) during 200m front crawl will cause it. Typically this equates to a swimming speed at, or in excess of, 90% of 200m race time.

If the amount of IMF is large enough, blood flow to the working muscles is compromised causing a faster rate of fatigue. Our earlier work suggested that inspiratory muscle strength must fall in excess of 19% for this to happen. As the magnitude of IMF reported in trained swimmers can exceed 19%, an accelerated rate of limb muscle fatigue is a real possibility.

We have also shown that swimming front crawl with IMF (we induced it before swimming) increases stroke rate and breathing frequency, and reduces stroke length during evenly paced swimming over a distance of 200m. As these changes are the opposite of those sought by coaches and swimmers, they have implications for training sets designed to improve stroke characteristics. Interestingly, we have found similar changes during flat out arms only front crawl swimming too.

The take home message is that IMF occurs during swimming, even in very well trained swimmers. It can negatively affect stroke characteristics, and has the potential to speed up the occurrence limb muscle fatigue. The good news is that we can do something about it.

3. Are there any ways coaches can measure IMF without high tech equipment? Without purchasing specialist kit, which can be expensive, it is not possible to verify the presence of IMF - swimmers will not necessarily be aware that they have it. Nevertheless, it is typically associated with an increase in the unpleasant sensation of breathing as well as an increase in breathing frequency and stroke rate. A word of warning here though, stroke rate and breathing frequency naturally increase with swimming speed independently of IMF. So an increase in stroke rate and breathing frequency should not automatically be taken as proof of IMF, even if swimmers are finding breathing unpleasant. IMF should be confirmed by a more direct measure and I would say that investing in a mouth pressure metre of some sort is worthwhile.

4. Any conclusions from the study to suggest whether an optimal breathing pattern exists for the 200 freestyle? The question of an optimal breathing pattern is an interesting one. One study suggested that breathing less frequently causes more IMF than breathing more frequently (one breath taken every fourth stroke instead of every second stroke). However, our research has been unable to support a relationship between breathing frequency and IMF. We have found that if IMF is induced before swimming, breathing frequency can increase as a result. But when we compared the magnitude of IMF between the four different strokes over a distance of 200m, we found no relationship between the magnitude of IMF and ad libitum breathing frequency occurring once every first, second or third stroke.
It is important not to ignore the relationship between breathing frequency, stroke rate and stroke length here. All three can change in the presence of IMF and we have found relationships between IMF and stroke rate, and IMF and stroke length. If IMF is shortening stroke length and stroke rate is increasing to compensate, breathing frequency will also increase because breathing is coordinated with stroke cycle, especially during front crawl.

The best we can say at present is that the magnitude of IMF is not affected by breathing frequency when swimmers take a breath no less frequently than once every third stroke during a competitive 200m swim. Clearly, more work is needed to understand the interactions between IMF, breathing frequency, stroke rate and stroke length. Focusing just on breathing frequency is likely to be too simplistic.

5. Can we draw any conclusions for other events (200 strokes, and all events of other distances?)
IMF is not just restricted to front crawl. In a recent paper we reported that the magnitude of IMF is similar between backstroke, breaststroke, butterfly and front crawl (range of 18-22%) following 200m race-paced swimming. Similarly, IMF has been observed after swimming distances of 100m, 300m and 400m front crawl. This indicates that it is not the distance per se that determines whether or not the inspiratory muscles fatigue, but the demands being placed upon them. This is what we would expect to see.

6. Any evidence that IMF can be cumulative, not just from one event (i.e. event hard training in high volumes induce IMF?) Typically research has examined the occurrence and impact of IMF in response to a single swim rather than a training set, or when competing in multiple events over the course of a day or two. How long IMF persists will depend on the type of fatigue experienced. It can take hours, maybe even days, to recover from low frequency fatigue, but only minutes to recover from high frequency fatigue (both of which are types of peripheral fatigue).

If the demands being placed on the inspiratory muscles continue to reduce their functional capacity, it would be illogical if IMF didn't accumulate. Indeed, we know that the magnitude of IMF is linked to swimming speed and hence exercise intensity. However, a fatigue limit would at some point be reached. It is also possible that the inspiratory muscles might start to recover during a subsequent swim. How this scenario would affect overall swimming performance we don't yet know. It is conceivable that swimming speed would need to be reduced in this situation. Alternatively the magnitude of fatigue, in for example the arm muscles, might be greater yet speed maintained. At present we simply don't know enough about IMF in swimming.

7. What do you think is the best way to strengthen the inspiratory muscles? 
It is clear that swim training alone is not sufficient to protect against IMF. Targeted training of these muscles is my advice i.e. inspiratory muscle training (IMT). There are various devices that can be purchased to train the breathing muscles, some are relatively inexpensive and others more so. These devices target either the inspiratory muscles or permit both the inspiratory and expiratory muscles to be trained (expiratory muscle fatigue is less frequently reported in the scientific literature but there is evidence that it too can negatively impact exercise).

There are also different types of respiratory muscle training e.g. pressure threshold training, flow resistive training and voluntary isocapnic hyperpnoea. Regardless of the type used, IMT is easy to incorporate into a training programme and can be undertaken by swimmers at home or could be integrated into a training session by a coach - typically the kit used is light and most devices are hand held. The type of IMT we administer (pressure threshold training) takes about 5 minutes to complete twice a day and consists of 30 breaths with a force equivalent to ~50% of maximum. We have seen that inspiratory muscle strength improves in as little as four to six weeks with such a programme, and so too does performance. However, the benefits appear to plateau after around six weeks and begin fade entirely after a few months if IMT is stopped. We are currently investigating how to incorporate IMT into a swimming training programme for long term benefits i.e. IMT periodization.

It is also relevant to note that a targeted inspiratory muscle warm-up can improve swim time. This can be done using the same IMT device immediately before a competitive event. Typically such a warm-up consists of 2, 30-breath sets at a load equivalent to ~40% of maximum. Importantly, whether undertaking IMT or an inspiratory muscle warm up, hyperventilation must be avoided as this can result in fainting. We always medically screen individuals before administering this training programme or warm-up, and I would suggest that anyone thinking of undertaking either checks with an appropriately qualified medical practitioner before doing so.

8. What are your thoughts on purging and controlled exhalation? As purging expels carbon dioxide and therefore prolongs the time before the urge to breathe sets in, it can be dangerous. This is more likely to be an issue for free divers though who may be several meters under water when the urge to breathe becomes over whelming.

Although purging can reduce breathing frequency and consequently the disruptive influence of breathing on stroke mechanics, swimmers do need to ensure that they are breathing frequently enough to meet the oxygen requirements of the working muscles. Performance of distances that rely heavily on the aerobic system to provide energy (I mean the re-synthesis of ATP here, which is the energy currency of cells) will be compromised if breathing frequency is too infrequent. So, there is a balance to be had.

With regards to controlled versus explosive breathing, I personally prefer controlled exhalation or trickle breathing. I find it more natural, less disruptive and less demanding.

9. What research or projects are you currently working on or should we look from you in the future? 
We have a number of swimming projects going on at present as well as some non-swimming breathing muscle projects. In a study soon to be published (International Journal of Swimming Kinetics) we present our findings linking the development and magnitude of IMF to swimming speed. Other swimming projects include how to incorporate IMT into swimming training programmes for long term benefits, the activity patterns of those muscles which have a dual function in aiding breathing and propulsion, and the impact of different breathing frequencies on muscle activity. 

Thanks Dr. Lomax

All You Need to Know About Inspiratory Muscles Part III

In part I and II of this series we discussed "normal" breathing biomechanics, muscles used during respiration and the current research surrounding inspiratory strength and performance.


In this installment, I will tackle my method for screening breathing and discuss the categories of respiratory strengthening exercises and a few of my favorite exercises. This will make your lungs the strong part of your swimming and lead to a successful, healthy career.





Most swim coaches are doing well training the inspiratory muscles with underwater and hypoxic training. Having to hold one's breath forces the diaphragm and secondary respiratory muscles to hold an isometric contraction. However, inspiratory isometrics can only go so far, eccentric and concentric respiration is needed to optimize swimming performance. Similar to a bicep curl, one doesn't strengthen these muscles by solely contracting their biceps, they get to LA Fitness and do curls for the girls!
Maybe Curls for the Guys...


Screen


With all the National team members at Santa Clara Swim Club I have them perform a specialized movement screen for swimmers. One aspect I closely monitor is breathing. I like to monitor relaxed inspiration/expiration and forced inspiration/expiration in standing, prone and supine. In the video, the swimmer knows I'm watching him breathe, but in reality I would not let them know what I'm looking for. This is difficult with deep breathing, but simply telling them to take a deep breath and encouraging them to take in more air brings out their competitive side and reveals their true breathing pattern.



In relaxed breathing, I look for a wave of motion, starting from the stomach rolling to the chest. Some experts suggest zero chest movement during relaxed breathing, but from experience a slight forward (not upwards) movement is fine.



During forced respiration, I make sure their diaphragm is contracting and sucking in. Make sure, they are still using their diaphragm during forced breathing.


My last screen looks at breathing during a maximal abdominal contraction. This will help differentiate the diaphragm and the abdominal muscles, indicating a week core or difficulties differentiating the diaphragm during exertion.



Four Horsemen
Different Kind of Four Horsemen
From my experience, there are four main categories to respiratory exercises. Sequentially checking one phase at a time is mandatory, as proper abdominal breathing is the foundation for the rest of the exercises.
  1. Abdominal Breathing
  2. Maximal Expiratory Contraction
  3. Maximal Abdominal Contraction with Respiration
  4. Maximal Abdominal contraction with Expiration
These four categories will help an athlete learn how to use their diaphragm during relaxed breathing, maximally contract the expiratory muscles, breathe in and out during stressful situations and solely breathe out when maximally contracting their abdominals.


Abdominal Breathing


The goal of this phase is to improve the strength of the diaphragm and differentiate the diaphragm from the secondary respiratory muscles. This form of respiratory training should use cuing and be progressed with resistance. Once differentiation is achieved, adding resistance is mandatory to strengthen this muscle.


Band Breathing




Maximal Expiratory Contraction


This phase teaches the athlete to maximally expel all the air in the body. This will get an excellent contraction of the transverse abdominus and diaphragm. This contraction will help an athlete use these muscles during fatigue. Maximal expiratory contractions will emphasize the concentric phase of these muscles, but make sure the athlete controls the eccentric phase of the contraction. Exercises should start statically (cat vomit) and progressed to dynamic movements, such as dead bugs or should flexions with maximal expiration. 


Cat Vomit



Maximal Abdominal Contraction with Respiration


Controlled breathing during a maximal abdominal contraction is essential for all elite athletes, especially swimmers. The abdominal muscles muscle be strong and stable providing a foundation for movement and athletic success. These exercises will work concentric and eccentric contraction of all the respiratory musculature during a maximal isometric abdominal contraction. Every athlete must breathe under extremely stressful situations, these exercises precisely mimic this situation.


See Maximal Contraction with Breathing Video


Maximal Abdominal Contraction with Controlled Expiration


In my opinion, this is the forgotten piece of breathing puzzles. Swimmers do a lot of hypoxic work stressing their inspiratory strength, but everyone forgets the expiratory muscles. All elite swimmers calmly expire with their face in the water (for freestyle) during highly stressful situations. They slowly release their air similar to a meditative state. Being able to breathe in a controlled fashion, will help your swimmers be relaxed during stressful situations, helping them save energy for the end of the race. These exercises should use some sort of external device (Kazoo or balloon) to ensure a constant outflow of air during a full contraction (note this athlete has a difficult time being relaxed, as noted with the jerky sound of his Kazoo).


Kazoo Abs



Wrap-Up


Well, if you've been with me for all three parts, great job grab a drink (refer to four horsemen) if needed to ease the brain cramp. But, remember cramps are potentially unused muscle fibers, so good work you're getting smarter!


By Dr. G. John Mullen, DPT, CSCS. He is the founder of the Center of Optimal Restoration and head strength coach at Santa Clara Swim Club.

All You Need to Know About Inspiratory Muscles Part II


In part I, I covered the exciting topic of breathing biomechanics and muscles associated with inspiration. These are the muscles noted with fatigue in swimming. Even though the last batch was the popular group to study, it is essential to know the other muscles involved in breathing and how to improve both forms of breathing. Now it is time to get into muscles used during relaxed and forced expiration and the research on inspiratory muscle fatigue and swimming, don't worry no statistician degree is needed.

Relaxed Expiration
As discussed in part I, the diaphragm is the main respiratory muscle. As the diaphragm contracts during relaxed inspiration, the lungs recoil back to their original position without any muscle contraction.  This is why breathing is considered an autonomous activity, it requires no thought, the body simply breathes....easy enough! The lungs are just like a like a balloon, if you blow up a balloon the outsides are stretched and forced to expand, but if you let out air, the balloon will recoil to its original position without any assistance.

Forced Expiration
Unlike relaxed expiration, forced expiration requires muscle activation.  Last weeks post on forced inspiration discussed a lot of foreign muscles, now lets talk about forced expiration and a few familiar muscle groups and a few you wouldn't expect...kegel’s baby!
  1. Internal intercostal: depresses and inverts lower ribs.
  2. Obliquus Internus: Compresses the lower part of the chest during forced expiration if the pelvis and spine are fixed.
  3. Obliquus Externus: Compresses the lower part of the chest during forced expiration if the pelvis and spine are fixed.
  4. Levator Ani: Compresses the lower part of the chest during forced expiration if the pelvis and spine are fixed.
  5. Triangularis Sterni: draws down the first rib during forced expiration
  6. Transversalis: Compresses the lower part of the chest during forced expiration if the pelvis and spine are fixed.
  7. Pyramidalis: Compresses the lower part of the chest during forced expiration if the pelvis and spine are fixed.
  8. Rectus Abdominus: Compresses the lower part of the chest during forced expiration if the pelvis and spine are fixed.

If the repeatedness didn't convey the message, these muscles are typically responsible for breathing while the pelvis and spine are fixed, stable, and stationary. This is essential and underutilized in studies which solely look at improving forced inspiration. A lot of the studies below only looked at inspiration, not looking at core stabilization, anatomy, or expiration. As you'll see in later posts, these factors are essential for optimal breathing.

Stats and Hypotheses
A lot of recent research has looked at inspiratory muscle training and inspiratory muscle fatigue and swimming performance.
  • Lomax 2011 found fatiguing of the inspiratory muscles before a 200 meter free at 85% race pace significantly affected breathing frequency, stroke rate and stroke length.
  • Brown 2011 determined there was no difference in inspiratory muscle fatigue between 100, 200 and 400 meter races. This is not surprising, since all stress the same energy systems...what about my 50 guys!
  • Kilding 2010 determined significant improvements with inspiratory muscle training, results indicated 0.6-1.7% improvement.  The largest improvements were in the 100 meter distance compared to the 400 meter distance.
  • Thomaidis 2009 looked at well trained adolescent swimmers (4:50 400 meter free time....maybe not that well trained) and determined inspiratory muscle fatigue occurs at the 300 meter distance.  This group determined as alterations in mouth pressure.
  • Jakovljevic 2009 compared breathing every two or four tims during a 90% race pace 200 meter free.  The results indicated decreased breathing, significantly increased maximal inspiratory pressure and determined inspiratory muscle fatigue is greater when breathing is reduced in front crawl swimming.
  • Mickleborough 2008 compared two groups: inspiratory muscle training plus swimming and a swimming only group. The researchers looked at lung capacities before and after 12 weeks and training and found appreciable improvements in the inspiratory muscle training and swimming group.
  • Wells 2005 determined 12-weeks of concurrent inspiratory muscle training and swimming compared to a sham respiratory training and swimming. The results showed improvements in both groups for respiratory tests.
  • Lomax 2003 found the 200 meter freestyle at 90-95% race pace induced inspiratory muscle fatigue.
Even our deep sea diving cousins have shown improved inspiratory muscle endurance with longer time to fatigue
  • Ray 2008 determined respiratory muscle training time significantly improved time to exhaustion (60%).
  • Lindholm 2007 found four weeks of inspiratory muscle training improved respiratory and fin endurance.
These studies have used various mechanisms to increase inspiratory muscle strength and found variable results. It is clear that swimming induces respiratory fatigue, but the main question remains, if swimming improves total lung capacity and forced expiratory volume (Mickelborough 2008), will additional inspirational training improve performance? Also, are the methods being used in these limited trials adequate to yield changes in elite athletes? I personally feel training these means will improve performance, but these studies have not been able to perform proper training.

I feel strengthening the diaphragm and methods where core contraction with relaxed and forced respiration need to be studied and could truly enhance inspiratory strength.  Remember, relaxed breathing should be autonomous and not call on every muscle in the body, so if you can don't utilize your primary respiratory muscles (diaphragm and intercostals), then you are fatiguing your secondary respiratory muscles, advocating the "cheater" muscles activity. Many athletes need to start simple, learning how to utilize the primary respiratory muscles with relaxed breathing, not allowing the cheaters to come around and or we'll have Joey Greco take care of them!

If one of the major breathing muscles (i.e. diaphragm) is not working properly the other muscles kick in and have to increase work. During forced respiration (athletic activities), if the primary respiratory muscles are not involved, one will be vulnerable to more injuries and stress on unnecessary structures. For example, if your diaphragm is inadequate, so your swimmer body calls on your well developed lats, pecs and traps to breathe, then these muscles will fatigue sooner, decreasing your swimming speed!

Round-up
With all the boring stuff out of the way, we can tackle how to screen breathing and methods to improve both inspiratory and expiratory muscles under maximal conditions.

By Dr. G. John Mullen, DPT, CSCS. He is the founder of the Center of Optimal Restoration and head strength coach at Santa Clara Swim Club.
 

All You Need to Know About Inspiratory Muscles Part I

No matter the distance, every swimmer is out of breath at the end of a race....excuse me if I just blew your mind!  This obvious statement has lead swim coaches to attempt various training means to prevent "being out of breath" as the main limiting factor in swimming.  The most common attempt was increasing swimming volume, while others implemented underwater training to improve this function, unfortunately some swimmers will have limitations secondary to inspiratory muscle fatigue.  Of the two aforementioned strategies, underwater training should improve isometric strength of the forced inspiratory muscles, but is this enough to maximize and optimize inspiratory muscle performance....
Quiet breathing is necessary to live and it is essential for athletes (and everyone) to breathe properly at rest.  At rest the diaphragm is the primary breathing muscle and improper use of their diaphragm can cause added stress to other structures.  From my experience, approximately 50% of Junior National level swimmers have improper diaphragm use and dissociation! 


This series will address the breathing muscles/biomechanics, importance of inspiratory strength, effects inspiratory fatigue demonstrates on performance, screening and lastly discuss a few dryland exercises to improve this deficiency. Lets start improving this number and optimizing swimming potential! 


Breathing Biomechanics
Breathing is a uniquely simplistically complex function performed by numerous muscles. It is commonly believed the chest is the primary location of respiration. This misconception is secondary to the location of the lungs, but when emphasized can lead to faulty breathing patterns.  Before we discuss faulty patterns, lets discuss the four types of breathing and typical biomechanics:
  1. Quiet Inspiration
  2. Quiet Expiration
  3. Forced Inspiration
  4. Forced Expiration
Here is what the John Hopkin's school of Medicine has to say about respiration: 

"During quiet breathing, the predominant muscle of respiration is the diaphragm. As it contracts, pleural pressure drops, which lowers the alveolar pressure, and draws air in down the pressure gradient from mouth to alveoli. Expiration during quiet breathing is predominantly a passive phenomenon, as the respiratory muscles are relaxed and the elastic lung and chest wall return passively to their resting volume, the functional residual capacity.

However, during exercise, many other muscles become important to respiration. During inspiration, the external intercostals raise the lower ribs up and out, increasing the lateral and anteroposterior dimensions of the thorax. The scalene muscles and sternomastoids also become involved, serving to raise and push out the upper ribs and the sternum.

During active expiration, the most important muscles are those of the abdominal wall (including the rectus abdominus, internal and external obliques, and transversus abdominus), which drive intra-abdominal pressure up when they contract, and thus push up the diaphragm, raising pleural pressure, which raises alveolar pressure, which in turn drives air out. The internal intercostals assist with active expiration by pulling the ribs down and in, thus decreasing thoracic volume."

During a deep inspiration these are the steps I look for:
  1. Diaphragm descends
  2. Ribs expand, elevate and rotate forward
  3. Shoulder blades move laterally

As stated, many people feel the chest and lungs need to be the primary mover for inspiration.  This is commonly due to the lack of understanding of which muscles are used during inspiration. Here's a list of the muscles during passive breathing and inspiration: 
  1. Diaphragm: This inspiratory muscle lies across the bottom of the rib cage and is essential for optimal swimming and breathing. Is commonly felt during belly breathing and helps raise and lower the abdominal wall, allowing expansion of the lungs. Used during all forms of breathing.
  2. Intercostal Muscles: These muscles help expand the chest and move the ribs, allowing for further chest expansion. Different fiber orientations are used during different times.  External fibers are used during inspiration and internal are used during expiration. Used during all forms of breathing.
  3. Scalenes: There are three scalene muscles which attach from the first few ribs to various vertebral structures.  These muscles should only be used during inspiration (preferably forced). 
  4. Pectoralis Minor: Runs from ribs 3-5 to a part of the shoulder blade (coracoid process).  Mainly used during inspiration. 
  5. Serratus Anterior: Spans from the outer surface of ribs 8 and 9 to the shoulder blade.  Used during inspiration.
  6. Sternocleidomastoid: Spans from the sternum and collar bone to the back of the head.  Used during inspiration.
  7. Levator Costarum: This muscle runs from the sides of the vertebrae to the posterior aspect of the ribs. Used during inspiration.
  8. Upper Trapezius: Runs from the back of the head to the outside of the collar bone. Used during inspiration.
  9. Latissmus Dorsi: Segments exist at multiple parts, most notably for breathing at the 3rd and 4th rib and shoulder blade running to the inside of the arm. Used during inspiration.
  10. Subclavis: Runs from the first rib to the shoulder blade. Used during inspiration.
As you can see, inspiration is a complex movement utilizing many muscles.  Ten muscles alone are used to breathe inward, this doesn't include the importance of expiratory muscles (mainly the abdominal muscles).   The epicenter of inspiratory breathing is the diaphragm, imagine if this muscle is not working correctly....more stress is placed on specific shoulder muscles, potentially leading to earlier fatigue in the arms and inspiratory muscle fatigue or worse, shoulder injury. Stay tuned for the next installments, focusing on the expiratory muscles, a literature on inspiratory muscle fatigue, screening and exercises.

By Dr. G. John Mullen, DPT, CSCS. He is the founder of the Center of Optimal Restoration and head strength coach at Santa Clara Swim Club.