Friday Interview: Stefan Szczepan Ph.D. Discusses Immediate Feedback in Swimmers

1. Please introduce yourself to the readers (how you started in the profession, education, credentials, experience, etc.).
Hi, my name is Stefan Szczepan. I'm a scientist at University School of Physical Education in Wroclaw, Poland and I work at the Department of Swimming. This year I received a doctor degree. I'm interested in motor control and learning included motor skill acquisition processes in water environment, especially teaching communication, forms of instruction, augmented feedback, and practice schedules. My mentor is Professor Krystyna Zaton, the head of Institute of Physical Activity in Water Environment in my University. She guides me in the science. I’m very proud with this relationship and I am very thankful for the trust and the knowledge transfer. My most recent research is about the impact of immediate verbal feedback and concurrent visual feedback on the improvement of swimming technique. I am the author or co-author of few articles in research journals. I connect theory with practice while teaching swimming and swimmers trainer.

2. You recently published an article immediate feedback and swimming. What are the different types of feedback?
Feedback is sensory information that results from movement. There are two types of feedback: intrinsic (integral) and extrinsic (augmented feedback). Intrinsic feedback is the sensory information arising as a result of physical activity by the means of sensory mechanisms (exteroreceptors and proprioreceptors). Information that derives from the receptor allows for movement regulation as well as the adjustment of motor task completion to the desired model of physical activity. Extrinsic feedback is formed after the completion of a motor activity and is transmitted by a third. Examples of extrinsic information are verbal communication, gestures, video, timer displays. There are several distinct types of feedback which are categorized according to the time of its transmission: concurrent feedback (provided during motor task concern continuous information), immediate feedback (provided during motor task concern discrete information) and delayed (transmitted after the completion of the motor action). Types of feedback are the most important for me. The most effective information is verbal and immediate. If you are interested in it – follow this link:

3. In your study you worked on improving the swimmers stroke length, can you explain how
you did this?
This study that we conducted together with Professor Zaton concerns the issues related to the importance of the transfer of feedback in an immediate manner to the learner during the learning swimming process. The work shows that the time in which the feedback reaches the learner is important in the motor control and that it improves swimming technique. The feedback communicated to the learner in real time manner regarding a performed motor function allows for the removal of errors in the short-term memory or prevents their formation. I chose a simple kinematic parameter of swimming movement as stroke length to confirm the importance of immediate verbal feedback. In this way the emergence of an error in the time-space structure of swimming motility was eliminated. The objective numerical dimension of the mistakes made allowed for a quantified relationship between the shortening of the swimming stroke length and the constant frequency of the propulsive movements. These factors led to a decrease in the efficiency of swimming, which was noted in the swimming velocity and a decrease in the economization of the swimming techniques, as indicated by the index SI. For these purpose I used special wireless tools including a system, transmitter and receiver for swimmer and teacher. This gave a possibility of a verbally and immediately control of swimming movement. It's an amazing technology that I spent significant money to develop and it works incredibly well.

4. What were the main results of your study?
The use of these tools in an experiment conducted on the experimental group, in which the information regarding the execution of the performed activity was transferred to students in an immediate manner, indicated that the swimming stroke is significantly improved along with an increased swimming speed while maintaining the same frequency of movements. This resulted in an effective movement in the aquatic environment. In the control group, however, where such information was not given, there was no observed swimming stroke elongation while maintaining the same frequency of movements. The transmission of immediate feedback in order to prevent the occurrence of errors or to eliminate them entirely, this also resulted in an improvement in the economization of swimming motor functions. The economization of swimming techniques was assessed using the index of SI [stroke index], which was considered as its measurement. Increase in the index SI values will see a decrease in the physiological cost of effort. In the control group this increase was not observed. It looks like that work tool and the assumptions of study can be used in any other motor swimming motor activity, not only stroke length. An example would be learning and improving movements of the legs and hands, body position in the water or coordination aspects, as well as other swimming motor elements.

5. What were the practical implications for coaches and swimmers from your study?
With the breaking of communication barriers, the following improve:
  1. Preventing the occurrence of errors and removing them from the motor memory.
  2. Improving motor structures and the cost reduction of physiological effort.
  3. Conditions will be created to improve the quality of swimming techniques with various degrees of accomplishment of utilitarian.
  4. Recreational values of physical culture, as well as antagonistic values noticeable in the competitive sports oriented towards maximizing achievement. 
The applied value of the method used, in which the verbal feedback was transmitted instantaneously in an immediate manner, in the practice of teaching and coaching is the enrichment of the communication technology regarding the correct structure of swimming motor functions. This is the main principle. The above assumptions are based on the physiological structure of human memory, whose different types are classified depending on how long information is stored in them. At first site, takes include human motor memory and second site augmented immediate verbal feedback. I give a method with used immediate verbal feedback for improves swimming technique and effectively the swimming learning process.
6. Do you think the results would be different if you had older, elite or untrained swimmers?
For sure people perceive information differently, due to age, sex or seniority. Probably we would observe differences between elite and non swimmers. This study showed the impact of immediate feedback on young swimmers. It can be apply for all swimmers, but the results may be a little different. In the future, I will plan other studies that answer on this question clearly.

7. Do you think immediate tactile or visual feedback would have different results?
Teaching and improvement of swimming technique is effective when external information is transmitted in three forms: words, images and practical actions. In case of the tactile I need to appeal to kinesthetic differentiation. It is one of the most important motor abilities. This ability is a precise perception of strength, time, and space. Feeling spatial movements, feeling of movement speed, what it’s called "water feeling” makes precise control of the movements. Tactile feedback can improve kinesthetic differentiation and makes to decrease energy cost and achieving better results. We deal this issue at my University. As regards the visual feedback I use special device. For example, it is the optical fiber giving the swimmer concurrent visual information. The light beam also provides the swimmer with the information on swimming speed. The ability to control the speed of swimming is an important part of preparation during swimming training. This is especially important when the desire is to obtain a pure training stimulus. Swimming with a defined - constant speed impacts on economical labor, and allows for maintaining a low physiological cost. Therefore, the development of a method that allows for acquisition and improvement of that skill is an important methodical goal in the process of swimming training optimization.

8. When working on biomechanics, how do you suggest tapering down feedback when the swimmer is progressing?
The role of the teacher is to provide feedback as long as the swimmer will acquire motor habit. Motor habit in human motor memory are formed after several thousand repetitions, therefore, the time of their acquisition is different. The next step in order to improve the quality of swimming mobility is multiple individual repetitions of the correct structure for motion, which was acquired by the use of immediate, verbal regulation regarding the swimming motor structures. Of course, if there are errors the teacher must again respond. Feedback can be addictive. In order to avoid the negative effects of frequent augmented feedback various techniques have been applied such as faded, bandwidth, summary, average or self-controlled schedules have been used.

9. Should teams utilize immediate auditory feedback?
I have a plan to develop my device and bring it to the swimming team. This allows the delivers of the individual swimmer and for the whole group. It will be easier to conduct training.

10. What makes your research different from others?
An innovative aspect of the subject undertaken is to identify empirically, that the time in which the

11. Which teachers have most influenced your research?
The person who influenced the most on my research has been my professor Krystyna Zatoń. For me she is a really big scientist. All the time she teaches me how to be better. It requires a lot of my sacrifices. Since I started working with her at Department of Swimming my life sped up, but I like it. I can learn a lot from a great biomechanic of swimming, a professor Marek Rejman too. We work together. I guess that we are good scientific team. Also I take inspiration from different scientists who are engaged in motor control and learning. There are many in the world, so I need to check of the database brand new publications.

12. What research or projects are you currently working on or should we look from you in the future?
I’m currently working on the evaluation of the achievements of swimmers. This evaluation is performed during motor activity in real time. Ability to take correct feedback to evaluation swimming technique can increase swimming performance. Usually, data are obtained from delay, e.g. with using movement analysis software. In addition, the aquatic environment interferes common available device for the evaluation, e.g. Infrared. Therefore I develop telemetry measuring swimming techniques. It enables in real-time provide feedback on the structure of the swimming movement. Wireless method of assessing swimming techniques can be used for research purposes to create maps of swimming techniques, to quantify. In addition, I’m interested in biofeedback and the implementation of transcranial magnetic stimulation (TMS) in the verification of feedback in swimming learning. Both issues seem to be good for my future. Many questions pertaining to increase the process of swimming acquisition and teaching remain unanswered and further research appears necessary. I hope it finishes successfully. I have one rule in my life, that says never stop.
information reaches the learner is important in the learning process and that it improves swimming technique. My work examines important aspect impeding the process of teaching of swimming and technique improvement. The interference in didactic communication – it is particularly noticeable when an exercise is executed in an atypical environment, for example in water. The aquatic environment hinders the reception of information because a number of disruptive factors such as the distance between the teacher and the learner or ambient noise favors errors in a given exercise. Thus, the environmental factors make it hard to use verbal feedback to its full communicative potential in the process of swimming acquisition or technique improvement. It may also be challenging to immediately eliminate or prevent (within short-term memory) errors as or before they appear, as I said early. I believe that the results of the present research work should contribute to defining the actual significance of immediate verbal feedback in swimming acquisition and improvement.

Thanks Stefan!

Do Growth Spurts Increase Injury Risk?

Take Home Points on Do Growth Spurts Increase Injury Risk?
  1. It seems the injury rate increases during growth spurts, but research is very limited. 
Growing pains are common in children, yet the cause and treatment of growing pains are not well known. Some hypothesize growing pains occur from muscles pulling on bones creating discomfort. Others believe increase in bone size simply increases discomfort from an increase in mechanical pressure. 

Growing pains are one type of "injury" during growth spurts. Specific adolescent injuries also exists, which I commonly see for Physical Therapy

Adolescent Injuries

  1. Osgood-Schlatter's Disease: is a painful swelling of the bump on the upper part of the shinbone, just below the knee. This bump is called the anterior tibial tubercle. It is believed to occur in active children who's patella tendon pulls on the tibial tubercle. 
  2. Sever's Disease: inflammation of the growth plate in the heel of growing children, typically adolescents. The condition presents as pain in the heel and is caused by repetitive stress to the heel and is thus particularly common in active children. It usually resolves once the bone has completed growth or activity is lessened.
  3. These are just a few common musculoskeletal injuries effecting children. Many other injuries can occur during growth spurts and parents for decades believe children have a higher injury risk during a growth spurt. Combine this injury risk with chronic poor posture from computers/electronics and early sports specialization and you've got a high injury risk for child...scary!

Growth Spurts and Injuries

Now, before we jump to conclusions about the injury incidence and growth spurts, we should consult
the limited literature:

Yukutake (2014) had 654 baseball players aged 6-12 years, all male, complete an original questionnaire that included items assessing demographic data, developmental factors (increase in height and increase in weight over the preceding 12 months), and baseball related factors. Multiple regression analysis was used to identify the risk factors for elbow pain during the 12 months prior to the study.

The data collected for 392 players without omissions or blank answers were submitted to statistical analysis. The results found that 19.1% of Little League baseball players had experienced elbow pain in the 12 months leading up to the study. The analysis revealed that height and increase in height were risk factors that increased the risk of elbow pain after adjustment for demographic data, developmental data, and baseball related factors.

Wild (2012) looked at ACL injury rates in adolescent boys and girls, noting girls have a higher ACL injury rate from:
  1. The effects of changes in estrogen levels on the metabolic and mechanical properties of the ACL
  2. Changes in musculoskeletal structure and function that occur during puberty, including changes in knee laxity, and lower limb flexibility and strength. 
  3. How these hormonal and musculoskeletal changes impact upon the landing technique displayed by pubescent girls.With limited research, limited conclusions are possible. 
However, the risk of injury increases during periods of growth. Unfortunately, recommendations now are purely theoretical. Some would suggest decreasing activity during maturation, but these are the peak years of motor learning. Instead, decreasing training volume and varying activities may be the best solution. This website has brought up the idea of a "swim stroke count", similar to a pitch for baseball. However, swim stroke counts may not be effective nor practical as many other factors influence musculosketetal stress on maturing bodies. Looks like we need more research on maturing athletic children!

  1. Yukutake T, Nagai K, Yamada M, Aoyama T. Risk factors for elbow pain in Little League baseball players: a cross-sectional study focusing on anthropometric characteristics. J Sports Med Phys Fitness. 2014 Apr 9.
  2. Wild CY, Steele JR, Munro BJ. Why do girls sustain more anterior cruciate ligament injuries than boys?: a review of the changes in estrogen and musculoskeletal structure and function during puberty. Sports Med. 2012 Sep 1;42(9):733-49. doi: 10.2165/11632800-000000000-00000. Review.
By Dr. G. John Mullen received his Doctorate in Physical Therapy from the University of Southern California and a Bachelor of Science of Health from Purdue University where he swam collegiately. He is the owner of COR, Strength Coach Consultant, Creator of the Swimmer's Shoulder System, and chief editor of the Swimming Science Research Review.

Life-Long Swimming Movement

The newest edition of the Swimming Science Research Review was released today. The theme of this edition is physiology, make sure to order your copy to stay current with the latest research on dry-land. Below are the tables of contents of this edition. 

September Swimming Science Research Review Tables of Contents

  1. Apheresis PRP has Minimal Enhancements  | PRP INJECTIONS
  2. Scapular Mobility is Altered in Impingement  | SHOULDER IMPINGEMENT
  3. Consider Function when Diagnosis FAI  | HIP FAI
  4. Review of Patellofemoral Knee Pain  | PATELLOFEMORAL KNEE PAIN
  5. Push-up Plus Minimizes Pectoralis Major Activity  | REHABILITATION
  6. Clinical Tests Cannot Diagnose Sciatica  | SCIATICA
  7. Manipulation and Sham Manipulation Improve Scapular Mobility  | MANIPULATION
  8. Swimming is a Possible Exercise During Pregnancy  | PREGNANCY
  9. Corticosteroids Improve Shoulder Pain Better than NSAIDs  | THERAPEUTIC DRUGS
  10. The Slump Test Identifies those with Mechanosensitivity  | SCIATICA
  11. Aerobic Training Increases Pain Tolerance  | PAIN
  12. Elite Swimmers have Altered Pectoralis Minor Length  | MOBILITY
  13. Sympatomatic Axillopectoral Muscles  | REHABILITATION
  14. Core Strength Testing  | LOW BACK PAIN
  15. Shoulder Dryland Training Decreases Imbalances  | SHOULDER STRENGTHENING
  16. Physical Therapy and Dry Needling have Similar Results in Myofascial Pain  | REHABILITATION
  17. Pain Impairs Performance  | PAIN
  18. Core Muscle Contraction Rate Varies with Position  | LOW BACK PAIN
  19. Screening Helps Predict Injuries   | INJURY SCREENING
  20. Rotational Differences in Overhead Athletes  | PREVENTION
  21. Alarming Injury Rates in Collegiate Swimmers  | REHABILITATION
  22. Latent Myofascial Trigger Points Inhibit Strength  | PREVENTION
  23. Shoulder Adaptations to Pitching  | PREVENTION
  24. Graston Technique Improves Range of Motion  | REHABILITATION
  25. Bench Press Shoulder Pain Case Study  | PREVENTION


Injuries occur in every sport. This incidence creates acceptance in coaching, as many turn
a blind eye to aches and pains. As we’re learning, this practice is hazardous, as pain and even latent trigger points (muscle knots) impair strength and biomechanics. In swimming, biomechanics and reducing drag directly correlates with swimming success. If athletes are having pain, from either an injury, pre-injury, or training, their performance and skill will obviously suffer. As motor learning research unveils, preventing soreness, monitoring injuries, and individualizing rest/recovery requires deep consideration. Remember, few swimmers, even elite swimmers, will make a career out of swimming. With this in mind, push you swimmers, safely, and intelligently for improvement with their acute and long-term health and performance in mind. If you coach high school-aged kids, take pride in having a high percentage of them swimming at Masters meets in their life, coaching high-school, or having their children swim. This may sound silly, but building life-long ambassadors of the sport will do more for the swimming community, than building a team of disgruntled, injured, and regretful Olympic Trial qualifiers in the sport.

Re-evaluate your team, educate your parents and athletic department and join the life-long swimming movement today!

The influx of online information makes it difficult to stay up-to-date with informative, accurate research studies. The Swimming Science Research Review brings you a comprehensive research articles on swimming, biomechanics, physiology, psychology, and much more!
This monthly publication keeps busy coaches and swimming enthusiast on top of swimming research to help their programs excel, despite being extremely busy.


Are Push-Ups Safe for Swimmers?

Take Home Points on Are Push-Ups Safe for Swimmers?
  1. Push-ups are a safe and effective exercise for swimmers with proper biomechanics and programming.
Questioning the safety of push-ups seems like it would make for a rather straightforward article, and 
if it was as straightforward as it seems, I would say that they are undoubtedly safe, and an extremely effective exercise for swimmers, at that; however, we need to create some more questions in order to form an educated answer. Is the coach qualified to supervise a push-up? Do they know what to look for in the exercise? Do they understand what variations may be best for different populations? Is the athlete doing enough mid and upper back work to balance the effect push-ups may have on the muscles of the shoulder girdle? 

Is the Coach Qualified to Supervise a Push-Up and Do They Know What to Look For?

When I say ‘qualified’ I don’t mean certified in Strength and Conditioning, or having a background in exercise science, all I mean by this, is that the coach or athlete has a basic understanding of what is really happening during a push-up, and what contraindications to look for in their respective populations.

Some of the most common flaws in an athlete’s push-up pattern are: poor arm position (either too close or too far from the body), extended or flexed head position (looking up, or down too far), and the most common—sunken hips with an arched back.

When judging arm position the rule of thumb is to put 45 degrees of space between the torso and the upper arm. This 45 degree position prevents the athlete from flaring the arms out too far and therefore placing too much stress on the shoulder girdle, it also prevents the arms from being in too close, causing too much flexion at the elbow, and therefore acute elbow pain or tendinitis.

A flexed head position is caused simply by the athlete either looking to make sure the arms are in the correct spot or just general poor body awareness (very common in swimmers). The best neck position is going to be neutral, where the head is looking straight down; not down at the feet, but simply down at the ground directly below their face.

An extended neck position is the result of some poor mechanics lower in the body. When the head is hyperextended, it is generally following the rest of the spine. When the spine is hyperextended, it is generally a result of passive restraints dominating throughout the core and hips. To mitigate this, the athlete must be cued to squeeze the glutes, as well as the abs. This whole complex of muscles firing is one reason why I trust athletes who tell me they can do 5 push-ups more than those who tell me they can do 50—at this number, it is very likely that the athlete is relying on passive restraints (ligaments, tendons, and bones) rather than actively engaging the appropriate muscles, and likely shortening range of motion, as well. 

If push-ups are done correctly, it is very possible for the abs and glutes to give out before the triceps or chest. This weakness usually subsides as the athlete becomes more experienced.

Does the Coach Understand What Variations May Be Best for Different Populations?

This question is crucial. Athletes have many different backgrounds, levels of experience, shoulder pathologies, leverages, and strength—all of which can drastically change exercise prescription. Most swimmers should stick with the simplest variations of push-ups, focusing on a tight core, as well as going through as large of a range of motion as possible (without pain). Even with a basic push-up many swimmers are not strong enough to demonstrate an entire set with decent form, and in many cases can’t even perform one single repetition. Many coaches here would have the athlete do push-ups from the knees, this variation however, tends to really hamper core activation, among other things, which drastically changes the movement. I prefer to have the athlete be assisted with bands. You can do this by setting up a large band around low pegs in a squat rack, then having the athlete lay over the band so that they are assisted as they get closer to the ground, and less as they get closer to the lockout, this is known as accommodated resistance. The further up the legs/torso that the band is placed, the athlete receives more assistance, the further down, less assistance is given. If a band is not available, a secondary option is to have the athlete perform a push-up to a bench or wall. Again, the more upright the athlete is, the most assistance they are receiving, so try to work the athlete to get close to the ground, and in the banded set up, have the athlete work at lowering the band placement each session. 

Some of my favorite progressions for the exercise are: hand-release, clapping, foot-elevated, single foot, gymnastic ring push-ups. These are all rather advanced and should only be attempted after a mastery of the standard push-up is present. On the other hand, some of the best regressions are the aforementioned band-supported, and incline push-ups (to a wall or bench).

It is very possible that having the hand on the ground during the push-up can irritate the athlete’s wrist. In this case, I suggest using dumbbells, placing them slightly outside of shoulder-width, and having them turned so that the hands can be slightly supinated—this will further reduce pain/ joint problems. Dumbbells with hexagonal bells are ideal here because they won’t roll away from the athlete during the movement. 

Is the Athlete Doing Sufficient Upper and Mid-Back Work to Balance the Effects of the Push-Ups?

Push-ups are partially so awesome because they can be done anywhere that there is the space to perform them, but what is not so awesome is that push-ups can make up far too much of a swimmers dryland program because there may be very restricted access to further equipment. Too many pressing exercises can pull the shoulder girdle forward over time causing pain, as well as poor performance. To counter problems associated with this, we must make sure that enough work is in place for the mid and upper back to keep the shoulder girdle in a neutral resting position. Many strength coaches go as far as saying that the ratio of pulling to pushing exercises should be 3:1, I however, think 1.5:1 is more reasonable, as long as the athlete already has a decent resting posture. 

This back work should hit the lats, traps (upper, mid, and lower), rhomboids, and rear delts. Great exercises for this are dumbbell rows, pull-ups, chest-supported rows, rear delt raises, among others. There are thousands of variations to the exercises already listed, focusing on these, and variations thereof, will give you enough dryland programs to last for years. 

Many argue that the demands on the back are high enough in swimming that there should be a reduction in back work during dryland to compensate. The work done by the back in swimming is usually too low in intensity/load to make significant hypertrophic differences, plus the fact that outside of the pool time, many athletes are in a state of flexion, be it at a desk at work or school, at home watching tv, or driving, which all needs to be accounted for (the 22 hours outside of practice are frequently overlooked during program design). 

The push-up is a fantastic exercise for swimmers and should be a mainstay of a swimmers’ training programs. Proper coaching of the exercise is more likely to determine its safety and effectiveness more so than any other factor. Keeping exercises balance is another huge key to long-term athletic development and safety, so be sure to implement a full dryland regimen to improve body awareness, speed, and conditioning.

Written by John Matulevich a powerlifting world record holder in multiple lifts and weight classes, as well as a Head D-2 Strength Coach, and previously a nationally ranked college athlete. His concentrations are in sports performance, powerlifting, and weight training for swimming. To learn more about how John trains his athletes, check his Twitter page: @John_Matulevich. He can also be reached at with inquiries.

Should Coaches Change Asymmetries in Swimmers: Part III

Take Home Points on Should Coaches Change Asymmetries in Swimmers: Part III
  1. An appearance of asymmetry does not automatically imply asymmetry of function
  2. Asymmetrical strokes may be related to physical characteristics and physiological capacity
  3. Working with an asymmetrical stroke is a mix of science and art
In previous posts we have reviewed literature on swimming and asymmetries (Part I, Part II). This installment will integrate information recently published by Dr. Formosa, summarized in his interview. What seems like a simple issue can get very complex when we look at all the factors involved. Many kids have had their strokes changed simply because a coach did not like how the stroke looked. Now, I’m not suggesting that kids should be allowed to swim without correction, but rather that correction must rely on more than “it looks bad.” 

Before getting to the interview, recall from a prior post in this series that, "Despite attempts to impose ideal symmetry, a perfectly symmetrical stroke and body are both unrealistic. We all have favored brain hemispheres, eye, ear and limb preferences along with structural differences in how our organs sit within our bodies. Asymmetry may also follow us into the water. But there is still good reason to make swimmers “less asymmetrical” even perfect symmetry is a fiction."

Nearly every swimmer brings asymmetries to the water. This isn’t necessarily a bad thing; just something to be accounted for when dealing with technique. A key point from the literature is that we can’t fully determine functional symmetry without measuring force. Yet surely there are ways to estimate whether someone is symmetrical or not, which leads us to Dr. Formosa’s work. 

As Dr. Formosa summarized, 

"The front crawl and backstroke research papers highlight that although an athlete may present with a similar timing from hand entry to hand exit the force profile that they are producing through the water is variable. Therefore, it should not be assumed that if a swimmer presents with a symmetrical timing pattern their force profile is also symmetrical. 

Further, elite athletes that apply force in water based sports such as rowing and kayaking have the ability to subtly manipulate their stroke to optimise force production. The complexity of symmetry is evident with the findings that although athletes demonstrated symmetrical timing their net drag force values were asymmetrical." (Formosa 2011, 2012, 2013)

Practical Application

While better swimmers often deliver force symmetrically, HOW they accomplish via individual can vary greatly and requires a more critical thought process than simply how the swimmer looks. The practical implication here is that coaches must consider all the information. 

We have written previously about movement screening to learn more about swimmers’ individual qualities. Not everyone has access to high tech underwater force measurement devices, but knowing your swimmer’s physical baseline is valuable. Some swimmers move their arms asymmetrically in 2D video but ultimately produce power with symmetry. 

Breathing patterns are also key factors, as preferred breathing style may lead swimmers to gravitate toward an asymmetrical looking stroke. Prior injury may also lead swimmers to develop protective patterns around injury. Yet thanks to the amazing plasticity of the brain, talented athletes can learn to develop force symmetrically despite lasting mechanical limitations. The extent to which this actually happens has yet to be studied but is a possible line of inquiry for future research as the foundation of the current literature on asymmetries expands. 


  1. Formosa, D. P., Mason, B., & Burkett, B. (2011). The force-time profile of elite front crawl swimmers. Journal of Sports Sciences, 29 (8), 811-819.
  2. Formosa, D. P., Sayers, M., & Burkett, B (2012). Front-crawl stroke-coordination and symmetry: A comparison between timing and net drag force protocols. Journal of Sports Sciences, 31 (7), 759 – 66.
  3. Formosa, D. P., Sayers, M., & Burkett, B. Symmetry of elite backstroke swimmers utilising an instantaneous force profile. Journal of Sports Sciences, Accepted 5th July 2013.
Written by Allan Phillips is a certified strength and conditioning specialist (CSCS) and owner of Pike Athletics. He is also an ASCA Level II coach and USA Triathlon coach. Allan is a co-author of the Troubleshooting System and was selected by Dr. Mullen as an assistant editor of the Swimming Science Research Review. He is currently pursuing a Doctorate in Physical Therapy at US Army-Baylor University.

Breast Size and Swimming

Take Home Points on Breast Size and Swimming:
  1. Swimming suits are ineffective in reducing breast displacement in freestyle and breaststroke.
Few in the swimming community are comfortable discussing today's topic: influence of trunk and breast during swimming. Considering the biomechanical influence of these body parts, it is an obvious research need. Also, if you talk or have worked with female swimmers, you'd likely agree the trunk and breast can influence swimming biomechanics and velocity. However, having research on the subject and understanding the effects of varying size breast with varying support helps coaches and swimmers make individual adjustments for each swimmer and their anthropomorphics.

There has been research on breast displacement in different bras during varying land activities (walking, running, etc.). This research found an obvious assumption: increased breast support caused decreases in breast displacement. Unlike most other sports, swimming is unique as it is in the horizontal plane, performed in water, both influencing breast displacement.

The breast likely influence body rotation during freestyle and backstroke. Previous work by Payton (1999) suggest rotation is approximately (66°) when taking a breath  than when breath holding (57°) whilst swimming at 1.8 m/s.

During short axis strokes (breaststroke and butterfly), results in breast displacement in the sagittal plane. Breaststroke causes approximately 63 degrees of trunk extension, causing resistance and slowing the swimmer (Colman 1998).

Understanding breast displacement is also important for non-elite swimmers, as some women experience pain during land exercise.

Mills (2014) had six large-breasted females (34 F, 34 F, 30 G, 34 G, 36FF and 34HH; age: 29; mass: 78.9 kg;  height:1.66 m) perform two swimming trials (one freestyle and one breaststroke). Each swimmer was recorded while swimming in the flume with multiple underwater markers on anatomical landmarks. Participants’ bra size was established by a trained bra fitter and fitted in the sports bra used for testing (using the fit criteria as set out by White and Scurr, 2012). The testing consisted of front crawl swimming at 1.08 m/s and breaststroke swimming at 0.94 m/s (water temperature: 30.5°C).

Breast Displacement During Freestyle

Mediolateral breast displacement (side to side), has a temporal pattern of medial, then lateral movement. These patterns were consistent, no matter the breast support condition. Breast displacement in the anterioposterior (forward and backward) varied with different support conditions. 

Overall, the greatest displacement occured mediolaterally in the swimsuit condition (7.8 cm), while the least displacement occurred in the sports bra condition (3.3 cm). Overall, the sports bra condition decreased breast movement, but not significantly. 

There was greater trunk roll in the sports bra condition, while the swimsuit had the lowest trunk rotation (43.1 vs. 39.3). However, different strategies were obtained with varying support for the participants. There was a strong negative relationship between trunk roll and anteriorposterior breast displacement and superiorinferior breast displacement. Overall, more trunk roll results in less breast displacement in freestyle. 

Breast Displacement During Breaststroke

Trunk extension exhibited a single peak of 55-60% of the stroke cycle. Superiorinferior displacement peaks inferiorly at 70% through the stroke in the bare-breasted condition, but not in the swimsuit and sports bra condition. 

Like freestyle, the bare-breasted condition had the greatest displacement in the superioinferior direction (3.7 cm) and the least in the mediolateral direction while wearing the sports bra (1.4 cm). This difference was significant. 

The least amount of trunk extension occurred in the swimsuit condition, but there were no significant differences between conditions. 

Breast Displacement Considerations for Swimming

This study notes minimal difference between the swimsuit and bare-breasted condition, suggesting current swimwear minimally supports women with larger breasts. Overall, the displacement of the breast was approximately half the displacement of land based sports. Unlike land sports, breast size did not impair body roll. However, more water becomes trapped in the the the swimsuit condition opposed to the sports bra condition. Overall, swim suit manufactures should consider swimwear with more breast support for maximizing performance. 

"The relationship between trunk roll and breast displacement was an interesting and unexpected finding as it was anticipated that women who exhibit greater trunk roll would induce significantly greater mediolateral breast displacement. There may be several reasons for this; first, the flow velocity of the water in the flume may not be uniform with changes in water depth. This may mean that the flow velocity is greater nearer the surface and decreases with depth, therefore affecting the drag on the swimmer. With increased trunk roll, the breast may be closer to the water’s surface and exposed to higher flow velocities resulting in a “pinning” effect on the breast, pushing it closer to the trunk, decreasing anterioposterior breast displacement and consequently minimising superioinferior displacement. Similarly, the breast being closer to the surface of the water may also cause an increase in wave drag (Vennell, Pease, & Wilson, 2006). An increase in wave drag may also have a similar “pinning” effect to that associated with an increase in flow velocity. Finally, flume construction may mean that the wave energy cannot be dissipated and is rebounded back off the side of the flume wall towards the swimmer. An increase in trunk roll may expose more of the trunk and breast to this rebound wave, again acting to “push” or “pin” the breast towards the trunk minimising breast anterioposterior and superioinferior displacement. It would be beneficial for a future study to examine any differences in breast motion during swimming both in the flume and in pool environments and also to manipulate trunk roll from low to high to determine its effect on breast displacement using an intra-participant design (Mills 2014".

Conclusions on Breast Displacement in Swimming

Greater breast displacement occurred in freestyle compared to breaststroke. The swimsuit was ineffective for reducing breast displacement. More research on elite swimmers and more advanced swimwear (ie high tech suits) will help suit manufactures optimize swim suits for women with varying breast size. Overall, breast size did not impair swimming trunk motion. 


  1. Mills C, Lomax M, Ayres B, Scurr J. The movement of the trunk and breast during front crawl and breaststroke swimming. J Sports Sci. 2014 Sep 5:1-10. [Epub ahead of print]
  2. Payton CJ, Bartlett RM, Baltzopoulos V, Coombs R. Upper extremity kinematics and body roll during preferred-side breathing and breath-holding front crawl swimming. J Sports Sci. 1999 Sep;17(9):689-96.
  3. Vennell R, Pease D, Wilson B. Wave drag on human swimmers. J Biomech. 2006;39(4):664-71.
By Dr. G. John Mullen received his Doctorate in Physical Therapy from the University of Southern California and a Bachelor of Science of Health from Purdue University where he swam collegiately. He is the owner of COR, Strength Coach Consultant, Creator of the Swimmer's Shoulder System, and chief editor of the Swimming Science Research Review.

Soft Tissue Therapy Improves Immune Function

Take Home Points on Soft Therapy Work Improves Immune Function

  1. Soft tissue therapy to the neck improves CD count, which may reduce illnesses.
High stress,  whether physical, mental, or social, drains the body and increases risk of illness. Every swimmer has become sick during a training trip (high physical stress) or even during taper (high emotional and mental stress). As a collegiate swimmer, a became very ill my Junior year, not being able to compete at the collegiate conference meet, practically wasting an entire year of training!

Now, you'll see many articles on foods, supplements, nutrients and other things which can prevent illness and these items do play a role, but I'm sure you haven't heard much about soft tissue work! Sure, having a massage feels good, but can it reduce illness? How about self massages also known as self myofascial releases (SMR)? 

Despite the common use of myofascial techniques, not much is clinically known about these methods. Despite the lack of knowledge, some in this field of research feel myofascial “therapy can have the following effects: enhanced circulation of antibodies in the fundamental substance; improved blood supply to areas of restriction through the release of histamine; correct orientation of fibroblasts; increased blood supply to the nervous tissue; and greater flow of metabolites from and to the tissue, thereby accelerating the wound-healing process (Fernández-Pérez 2012)”.

For investigating the potential health benefits, Fernández-Pérez (2012) took blood from thirty-nine healthy men without any pathological condition before and after a fifteen minute session of myofascial techniques to the suboccipital and deep anterior cervical fascia. A control group consisted of simply not receiving any treatment. Before the study, immunological markers did not differ between groups. After the soft tissue work, the experimental group had a significant different cluster of differentiation (CD) count after the treatment, specifically with an increase in CD19 (a B-lymphocyte antigen).

Clearly, this is a preliminary study and simply assuming this increased CD count will reduce illness is not appropriate. Also, assuming the actual soft tissue manipulation was the reason for the higher CD count isn't known, as the researchers suggest simply “human touch” may trigger this immunological response. However, this coincides with other findings which suggest myofascial techniques play larger role than muscle manipulation. Specifically, older studies have found alterations in the sympathetic nervous system (changes in blood pressure and heart rate after myofascial techniques). Also, CD19 plays a role in B lymphocyte function and may initiate improvement in connective tissue, minimally important for immune function, but maybe helpful for injuries and microinjuries.

Conclusion on Soft Tissue Therapy and Immune Function

This suggests myofascial techniques to the cervical muscles may modulate sympathetic and immunological function. However, future studies must assess this result in more diverse populations, specifically those with preexisting injuries. Also, further research into self myofascial releases are mandatory, as we are still not sure if SMR has similar results as manual therapy performed by another person. As a Physical Therapist at COR, I think SMR is beneficial, but doesn't provide as good of results (there are a lot of theories for this!).

Want to learn more about mobility, self myofascial releases, and dynamic mobility for swimmers? Check out Mobility for Swimmers!


  1. Fernández-Pérez AM, Peralta-Ramírez MI, Pilat A, Moreno-Lorenzo C, Villaverde-Gutiérrez C, Arroyo-Morales M. Can Myofascial Techniques Modify Immunological Parameters? J Altern Complement Med. 2012 Nov 23. [Epub ahead of print]

By Dr. G. John Mullen received his Doctorate in Physical Therapy from the University of Southern California and a Bachelor of Science of Health from Purdue University where he swam collegiately. He is the owner of COR, Strength Coach Consultant, Creator of the Swimmer's Shoulder System, and chief editor of the Swimming Science Research Review.

Early Diversification for Swimmers

Take Home Points for Early Diversification for Swimmers
  1. When to begin specialization is an individualized process.
  2. Some elite performers benefit from early specialization, but it may not be best for the majority.
  3. Weighing the risk of early specialization is mandatory for determining time for specialization.
Sports specialization is defined as intense, year-round training in a single sport with the exclusion of other sports. Sports specialization is occurring earlier than ever before. Previous surveys found parents were the main motivator to initiate a sport, where coaches were the main reason behind specialization. I discussed this topic in detail with much backlash on Swimming World, overall suggesting a two-month break rule. Once again, this is not a system for everyone, at every point in their career, instead a rough suggestion for youth athletes. Nonetheless, the idea of early sports specialization exist and become more pronounced with Michael Phelps succeeds with early specialization. However, sometimes considering trends in other sports questions the current state of our own sport. Other times, and admittedly most often, it bears minor help on the sport of swimming.

Jayanthia (2012) looked at sports specialization in tennis players. Rates of sports specialization appear to increase with age. A study of 519 US Tennis Association junior tennis players found that 70% began specializing at an average age of 10.4 years old. Specialization rate gradually increased after 14 years, with 95% of players having specialized by age 18 years. However, enjoyment and satisfaction ratings decreased in players older than 14 years old. 

Musicians have been believed to improve from early specialization. However, the rates of success with sporting specialization are unclear, despite frequent expert opinions. A few studies have actually suggested elite success inversely correlated with training volume at the age of 14.

Early diversification often leads to more success and is suggested to provide an: “athlete with valuable physical, cognitive, and psychosocial environments and promotes motivation (Jayanthia 2012).”

As it seems, the benefits of early specialization are uncertain, but the risks appear consistent: more burnout, less enjoyment, more injuries

Some degree of sports specialization is necessary for elite success, however it seems imperative to delay early intense specialization for long-term enjoyment, health, and success for the majority of athletes. 

Practical Implication

Early exposure is likely necessary for the creation of ultra-elite swimmers, yet early specialization increases the likelihood of early burnout and quitting. For this reason, it is essential to start children early in swimming, but encouraging them to participate in other sports and activities until their post-pubescent years.

Each child should have the opportunity for elite performance, unfortunately this situation is too often rushed. As Dr. Sokolovas notes, "females need about 9 to 10 years of year round training, while males need 10 to 11 years.” This results in many parents, coaches, swimmers, pushing their kid at the age of 4 to swim year round, peaking at 14 or 15. 

Why rush?

Sure there are unfortunate reasons, like swimming status, but this isn’t needed. Instead
of looking at the amount of time for elite swimming success as in years, many think about it in hours, but remember, there are a lot of ways to get hours in swimming (12 years of swimming, 20 hours a week, for 10 months a year equals 10,080 hours for example). Unfortunately, newer research is suggesting the time equation or 10,000 hour rule is over simplified. Instead, quality of training, physical capacities, and many other factors are involved as well as training hours.

Even Dr. Sokolovas says “year-round” training is training 48-50 weeks a year, I just argue this can be extended and potentially stretched out for longer athletic development. Perhaps swimmers should doubles 3 days in a row, then a day off for an entire season! Maybe this scenario would provide the recovery needed for long term success and enjoyment.

No matter what training frequency and break scheduled is considered, make sure it receives thorough investigation, as the plan a 10-year-old performs influences their enjoyment and health, not only for sport, but also exercise. If the swimming community is disrupting swimmer's long-term health by increasing the injury risk and enjoyment of exercise, then the current status quo requires reconsideration. Ask this, as well as:
  • Are swimmers getting faster are more swimmers getting faster earlier in their career? 
  • Are there more elite swimmers or just more fast swimmers? 
With data and research, these are simple questions, but difficult answers. Nonetheless, the should guide future plans for long-term success and emphasis on early diversification/specialization for swimmers.


  1. Jayanthia, N, Pinkham, C, Dugas, L, Patrick, B, LaBella, C. Sports Specialization in Young Athletes Evidence-Based Recommendations. Sports Health: A Multidisciplinary Approach October 25, 2012. 1941738112464626.
  2. Sokolovas G. Why Swimmers Need to Train Year Round
By Dr. G. John Mullen received his Doctorate in Physical Therapy from the University of Southern California and a Bachelor of Science of Health from Purdue University where he swam collegiately. He is the owner of COR, Strength Coach Consultant, Creator of the Swimmer's Shoulder System, and chief editor of the Swimming Science Research Review.