Swimming Energy Calculator

OttrLoggr: Energy Use Calculator

Swim Energy Usage

Distance
Time
:
RER
Stroke

RER Value Guide

Slow (0.7)
A1 band - warm-up, recovery, cool-down sets
Moderate (0.85)
A2 band - aerobic capacity sets
Intense (1.00)
A3 band - aerobic power, VO2max sets

Data Source: Zamparo P, Bonifazi M (2013). Bioenergetics of cycling sports activities in water.

Coded for Swimming Science by Cameron Yick

Freestyle data

Velocity
/s
Cost
kj/
Total Cost
kj
Calories
kcal
Carbs
g
Fat
g

Quick Food Reference

Bagel
48g Carbs
Apple
25g Carbs
Peanut Butter
16g (2 tablespoons) *

Does Greater Force Production Equal Faster Swimming?

Measuring force in the water is difficult, let alone the contribution of force in swimming success.
Before we can address if force production equals faster swimming, we must review how force is calculated in swimming research. Must of this piece is taken from Sacilotto (2014), if you are interested in reading more.

Unfortunately, only a limited number of reviews identify resisted, or drag forces, in swimming.

The drag force is the force component parallel to and in the same direction as the relative fluid force. Drag force D is calculated by: Df = 1/2CDrv2A, Cd is the drag coefficient, and r is the density of fluid, v is the velocity of the object and a is the frontal surface area of the object. 

The resistive forces the swimmer interacts with in the water are form, wave, and frictional drag. These are influenced by the swimmer's velocity, boundary layer, shape, size, and the frontal surface area. In swimming, the resistive forces are termed the active and passive drag. 

  • Active drag is the water resistance associated with the dynamic swimming motion.
  • Passive drag is the water resistance that a human body experiences in a fixed or unchanging posture.
Komogorov (1992) determined active drag varies between individuals and seems to related to swim technique and anthropometry. For swimming, drag can be active or passive. However, we will only discuss active drag.

Active Drag and Swim Performance

The two most commonly identified factors for swimming speed are propulsion and drag. The ability to reduce the active drag encountered allows propulsive forces to be efficiently applied, increasing swimming velocities. Elite swimmers are more able to reduce active drag than nonelite swimmers (Kolmogorov 1992). This efficiency allows elite swimmers to minimize wasted kinetic energy. 

However, Hollander (1985) did not find a significant correlation in active drag and swim velocity at a constant velocity. 

Mechanical Power Output in Swimming

Some suggest swimming performance is defined by the relationship between the useful mechanical power output, active drag, the hydrodynamic force coefficient (drag coefficient) and the maximal free swim velocity. The mechanical power is the power delivered to overcome drag. Swimming power is evaluated as the product of swimming drag (D) and velocity (v):
P= Dv
The ratio between the useful power and the wasted kinetic energy is defined as the propelling efficiency of a swimmer: 
hP = Pd/PO

hP is the propelling efficiency and Pd is the useful power.

Techniques of Drag Assessment

Measurements of active and passive drag have been attempted through the years. However, there is much controversy on the techniques. The energetics approach, numerical solutions and experimental techniques have been developed and use to estimate or measure drag forces in swimming.

Energetics Approach

The energetics approach is also coined theoretical calculations, investigates the relationship between
energy costs of swimming, the velocity, and the overall mechanical efficiency of the swimmer and the body drag. This is used for deciphering the mechanical power output of a swimmer during free swimming. This approach tows a swimmer at a given pace, which is maintained by a towing carriage with known additional weights to provide assistance/resistance. The maximal oxygen consumption is then recorded. The body drag is determined by adding (or subtracting) extra loads to (or from) swimmers moving at a known speed. The extra drag was measured and related to the swimmer's energy expenditure to calculate the drag and swimmer's mechanical efficiency. 

Di Prampero (1974) identified a linear relationship between drag and maximal oxygen consumption at constant swim velocities, which led to this technique of determining drag as a function of VO2net. Clarys stated “extrapolated the linear regression between VO2net and the added propulsion and added drag to VO2net = 0.” At a constant mean velocity, the mean propulsive force exerted by the swimmer will be equal and opposite to the active drag produced.

Similar values of active drag were found when comparing propelling efficiency values as a percentage. In this studies the drag values were similar, but the authors assumed propelling efficiency did not change where active drag was calculated. It is likely propelling efficiency will change, even at a constant speed, when external loads are applied, as is this case in this approach. Also, small changes in VO2net values due to small deviations in propelling efficiency will be amplified by the extrapolations that are a basis for these studies. Van de Vaart believes this form of testing overestimates active drag. Also, a snorkel is used to measure VO2net, altering the frontal surface area which likely modifies the active drag.

Numerical Simulations

These models use the computational modeling of the water flow surround the swimming to determine
the resistive forces. This is typically through computational fluid dynamics (CFD). CFD solves the analyses problems using fluid flow by means of computer-based simulations. It creates a 3D model of a swimmer and simulates their movement patterns. CFD simulations eliminates within-subject variability, allowing the same input you always have the same output. Bixler (2007) studied the water flow and drag force characteristics on a human, a CFD, and a mannequin. Although the study only assessed passive drag, the results were positive, as the submerged human body had similar passive drag. For CFD to become a readily available method of resisted force assessment, basic kinematic measures during free swimming need to be collected, like the ability to collect instantaneous swim velocity, or knowing where the center of gravity is while a swimmer is swimming. A further limitation is that CFD simulations require a lot of computer time and knowledge of the process, making it difficult for coaches and scientist.

Experimental Techniques

Experimental techniques attempt to accurately determine the resistive forces encountered by a swimmer. This often uses the measuring active drag system (MAD-system), and the indirect techniques of collecting active drag values, the pertubation method (VPM), and the assisted towing method (ATM).

Measuring active drag system 

Hallander (1986) developed this system which measures the drag force generated by a swimmer, which enables the calculation of the propulsive force production during the trial. The assumption is made that the mean propulsive force would be equal to the mean active drag values when the swim velocity is constant.

The MAD-system, requires the swimmer to push off from fixed pads underneath the water. Originally this technique different but constant velocities. The swimmer's legs were restricted by a small buoy. The depths of the pads were able to be adjusted for the swimmer’s height as well as the distance between pads. For each trial, the registered output signal of the force transducer was transmitted telemetrically to determine mean force. The average propulsive force was calculated by integration from the force registrations at a constant swim velocity. The swim velocity was determined from the sample frequency and the pad distance (between the second and final pad).

Toussaint (2011) represents the calculation for drag as Da=Kv2, where Da represents total active drag, K is the constant (incorporating the density, coefficient of drag, and frontal surface area), and v equals swimming speed. 

Although this technique has been used extensively, it has much criticism. For one, it limits the swimmer's natural stroke mechanics, and it can only be used at a constant velocity. Also, this technique should only be compared against itself or if a swim velocity is the same between techniques. It also uses pads and doesn't allow the swimmer to be in contact with the water. This may alter the normal hand trajectories. Having the pads requires more coordination to constant the pads and may slow down effort. Also, the use of a pull buoy alters swimming biomechanics.

Velocity Perturbation Method 

The VPM method is based on the assumption that a swimmer is capable of producing an equal amount of useful mechanical power output and that the simmer will swim at a constant velocity. This technique is seen as a progression from the energetics approach in estimating active drag, without the use of maximal oxygen consumption. In the VPM, a swimmer must produce two equal maximal efforts. This is typically used over 25 m, but has been used in other distances. The first swim is freely, without any attachments, and the second is swum with a hydrodynamic body attached to the swimmer, creating extra resistance. The maximal mean velocity when swimming with the hydrodynamic body was compared with the maximal mean free swimming velocity, which along with the a known addition resistance is used to calculate active free drag for free swimming:
DA=Dbvbv2/v3-v3b
Db is the additional resistance from the pertubation buoy and vb and v are the swimming velocities with and without the hydrodynamic body. 

This method is frequently criticized, as it is an indirect measurement of active drag, and may overestimate active drag. It is also assumed participants use the same velocity level. This is difficult due to the added device and it is found that the maximal error due to stroke cycle fluctuations is around 6 - 8%. The other error is that it is difficult for non-elite swimmers to swim with this added device. 

To allow different skill levels, different hydrodynamic bodies were developed. However, no matter the size, a hydrodynamic body will still alter swimming skill. Xin-Feng (2007) created an apparatus which stayed in a steady position and minimizes the floating movement of the hydrodynamic body. During Xin-Feng's study they measured the variation in tension of the tread when the gliding block was moved by the swimmer. The results revealed that the tension of the thread fluctuates, revealing the additional resistance does not have a constant value as assumed. 

Despite the limitations of the VPM, there are benefits. For one, the VPM method is easily set-up at a pool, allowing coaches and athletes use. It also doesn't need adaptations for different strokes.

Assisted Towing Method

The assisted towing method (ATM) technique is essentially the reverse of the VPM method, by assisting, instead of resisting the swimmer. The ATM is also based on the equal power assumption and the constant velocity assumptions. However, as outlined by Xin-Feng (2007), a swimmer will not be swimming at a constant velocity at any point throughout a maximal effort due to the intrastroke fluctuations in the swimming. Such fluctuations are a result of the intrastroke forces that are generated during a natural arm cycle. kicking also leads to fluctuations. 

Mason (2011) compared constant active drag values with fluctuating active drag values. During these trials, the mean velocity maximal free swims (individual swimming without any attachments) and the mean velocity of the towed swims (towed from the hip using the dynamometer) are used to calculate for drag with respect to the drag force required to tow the swimmer. This helped create the VPM equation:
Da=Fbv2v1^2/v2^3 - v1^3
Fb is the force required to tow the athlete at the increased speed as measured from the force platform, v2 is the increased tow velocity, and v1 is the maximal free swimming velocity. Similar to the VPM approach, when using this system with a constant velocity, the dynamometer is set to 5% faster than the swimmer's mean maximum free swim velocity with a high force selection to allow for a near constant tow. To allow the swimmer's intrastroke fluctuations, the force setting on the dynamoeter is reduced and the velocity setting is increased to 120% of the swimmer's maximum free swim velocity. Along with these changes in set force and velocity settings, a paramter on the towing dynamometer is
altered so that when the force setting is reached it will fluctuate the tow velocity to maintain that force setting, therefore allowing the intrastroke fluctuations. The force setting used is a predetermined fraction of the swimmer’s passive drag tow (streamlined tow at the swimmer’s maximal free swim velocity) and is different for every individual swimmer. Despite the increase in the velocity, setting the mean tow velocity will still equal between 5% and 10% greater than the swimmer’s maximal mean free swim velocity; however, when calculated, the velocity profile will demonstrate the intrastroke fluctuations. The results from the fluctuating trials seem to demonstrate a smoother drag profile, more repeatable results, more resembling free swimming characteristics. The ATM allowing a fluctuating tow velocity in active drag estimation, is still in its infancy. However, the results shown thus far are positive in being able to decipher exactly what affects performance during free swimming. When towing with a constant velocity it has been assumed that drag was equal but opposite in direction to propulsion. However, when utilizing a tow allowing for instrastroke fluctuations, this can't be true. A recent study using ATM attempted to calculate a swimmer's propulsive profile, net force, and acceleration curves while allowing intrastroke velocity fluctuations:
P=d/dt (mv)-DA
P is propulsion, m is the passive drag force of the swimmers (as a substitute for the mass of a swimmer), v is the velocity profile, and Da is the active drag. 

Although ATM is promising, validation is needed. Although a small sample, a recent study revealed very good reliability value for within-subject mean active drag values (interclass correlation of 0.91, at a confidence limit of 95% and a likely range of 0.58 and 0.98). Future studies must investigate into whether the velocity/force profiles obtained during this technique mimic real stroke mechanics. However, until accurate measurements of basic kinematics while a swimmer is submerged in water, research with the method is under scrutiny. Also, the use of this system for other strokes is not well established due to the intracyclic variations between strokes.

So Does Great Force Production Equal Faster Swimming?

The simple answer is no. Elite male sprinters have a peak force of 50 – 80 pounds and on average 20
– 31 pounds of resultant force (Havrulik 2013). Compare this to the ~800 pounds of force created by Olympic track sprinters. Another way to look at it, if simply increasing force resulted in faster swimming, then the strokes with the highest force production (fly and breast), would be the fastest (Morouço 2011). 

Instead, it seems variation in force production plays a larger role in swimming speed. This isn't to say, if you improve your swimming force production, then you won't be a better swimmer, as you may improve your force production as you decrease your variation in force production. 

Also, we must consider the timing and displacement of force. Sometimes, a swimmer will create force, but in a wasted manner, ie when their hand is not facing perpendicular to their body or as their arm is out of the water. This is a wasted increase in force production.

Overall, a careless increase in force production doesn't necessarily increase swimming velocity. However, increasing force production in a vacuum will increase swimming velocity.

Now the question is how can you improve this force production with altering the rest of their biomechanics...


Reference:
  1. Mason B, Sacilotto G, Menzies T. Estimation of active drag using an assisted tow of higher than max swim velocity that allows fluctuating velocity and varying tow force. Paper presented at: 29th International Society of Biomechanics in Sports; July, 2011; Porto, Portugal.
  2. Bixler B, Pease D, Fairhurst F. The accuracy of computational fluid dynamics analysis of the passive drag of a male swimmer. Sports Biomech. 2007 Jan;6(1):81-98.
  3. Xin-Feng W, Lian-Ze W, We-Xing Y, De-Jian J, Xiong S. A new device for estimating active drag in swimming at maximal velocity. J Sports Sci. 2007;25(4):375–379.
  4. Toussaint HM, Roos PE, Kolmogorov S. The determination of drag in front crawl swimming. J Biomech. 2004;37(11):1655–1663.
  5. Sacilotto GB, Ball N, Mason BR. A biomechanical review of the techniques used to estimate or measure resistive forces inswimming. J Appl Biomech. 2014 Feb;30(1):119-27. doi: 10.1123/jab.2013-0046.
  6. Hollander AP, De Groot G, Van Ingen Schenau GJ, et al. Measurement of active drag during front crawl arm stroke swimming. J Sports Sci. 1986;4:21–30.
  7. Di Prampero PE, Pendergast DR, Wilson DW, Rennie DW. Energetics of swimming in man. J Appl Physiol. 1974;37(1):1.
  8. Kolmogorov SV, Duplishcheva OA. Active drag, useful mechanical power output and hydrodynamic force coefficient in different swimming strokes at maximal velocity. J Biomech. 1992;25(3):311–318.
  9. Toussaint HM, Beelen A, Rodenburg A, Sargeant AJ, de Groot G, Hollander AP, van Ingen Schenau GJ. Propelling efficiency of front-crawl swimming. J Appl Physiol (1985). 1988 Dec;65(6):2506-12.
  10. Havruilk, R. Personal Communications. San Jose CA. September 2013.
  11. Morouço P, Keskinen KL, Vilas-Boas JP, Fernandes RJ. Relationship between tethered forces and the four swimming techniques performance. J Appl Biomech. 2011 May;27(2):161-9.

Swimmer's Shoulder Return to Swimming Program

Take Home Points:
  1. When returning from any injury (in this case a shoulder injury), many training alterations are required.
  2. These are general outlines, please see a healthcare professional if you have shoulder pain and set an individual return to swimming outline.
  3. Don't rush your return to full swimming practice. Work on biomechanics, reduce pain, and elongate your swimming career!
The commonly used plans for returning a swimmer to the pool after a shoulder injury have many flaws. Swim coaches and health care professionals have vastly different views, both contributing to the problem. Swim coaches do not want their swimmers to miss any time from the pool as they feel any missed time will prevent progress. Health care professionals want swimmers to take weeks off from swimming to allow full recovery. The appropriate approach lies somewhere between these two options.

Yes!! He recovered from swimmer's shoulder!
A typical health care approach to recovery from a shoulder injury includes numerous “blank periods”. This is when a swimmer is not receiving care or swimming as they wait to be seen by the next professional. After these sessions, the health care professional expects the swimmer to return to the pool after their symptoms have alleviated, but often times don't necessarily stress their shoulder for the demands required in swimming. In their eyes, this is considered a successful treatment; unfortunately time away from the pool causes an athlete to lose “feel” which can only be acquired and maintained by spending time in the water.

This is the best-case scenario, but sometimes the symptoms never improve. Sometimes the swimmer will continue to swim with the pain. Other times, the symptoms may disappear and the swimmer will return to practice, hop in the pool, go full throttle, only to have the symptoms return. This reckless approach will likely cause a re-injury and add more “blank periods”. This is a sad, all too common case, for many age-group swimmers.

Many health care professionals don’t know how to safely return a swimmer to the pool with guidelines to benefit recovery. Applying continual, gradual swimming stress is essential to see if the swimmer’s shoulder pain is improving. Therefore, it is important to know their current pain level and have them progressively return to the pool. Tiers of limitations can be used to gauge improvement, yet maintain neural feel. Knowing an athlete's current level of pain will help in monitoring whether or not their symptoms are improving, as it is unlikely for the athlete to go from 8/10 to 0/10 pain after a few sessions with the rehabilitation specialist, especially if these symptoms are long-standing. Helping them progress with milder and fewer symptoms allows the swimmer to see progress, keep their sanity, and stay positive as they return to the pool.

After working with thousands of swimmers, I began piecing together simple tricks to speed recovery while maintaining “feel”, thereby preparing the athlete for a full return to practice.

Follow these guidelines closely to ensure shoulder recovery, while maintaining “feel” and strength in the water.

Return to Swimming Freestyle Biomechanics

Proper technique for injury prevention is essential. I’m sure not all of the readers will agree with these biomechanical corrections for swimming propulsive reasons. However, I recommend them because they will put less stress on the shoulder joint and muscles, the primary correction for those with shoulder pain. During freestyle, ~75% of the “most pain” occurs during the first half of the pull and ~18% of pain occurs during the first half of the recovery (Pink 2000).

The most common biomechanical causes of shoulder pain in swimmers are:

Crossing Over

Crossing over occurs when the swimmer initiates their catch and brings their arm across their body. When the arm crosses the body, it closes the space on the anterior shoulder. The anterior shoulder contains the supraspinatus, the most commonly injured rotator cuff muscles.

Solution: The most common reason for this error is a lack of emphasis on biomechanics. Most swimmers can prevent a crossover catch with concentration and appropriate cuing from their coach.

If the swimmer lacks shoulder blade stability, this may be causing them to cross their arm across their body on the catch. Stabilize the shoulder during the initial catch by performing the compact position. In the compact position, it is nearly impossible to cross over and impinge the anterior rotator cuff muscles.

Thumb-First Entry

If an athlete enters with his or her thumb, the whole hand can enter through a smaller hole, decreasing drag. However, many athletes achieve a thumbs-first entry through shoulder internal rotation. This orientation can stress the anterior structures of the shoulder and increase the risk for shoulder impingement.

Luckily, the thumb first entry can be achieved with no movement at the shoulder. Instead, instruct your athletes to use forearm pronation (rotating the forearm inwards) instead of shoulder internal rotation to get their thumbs to enter first, decreasing the amount of drag on the entry.

Solution: Either instruct your swimmers to enter finger tipss first or thumb first with only forearm pronation, a difficult but beneficial difference. Consider performing finger tip drag drills or hesitation drills just prior to entry to perfect the entry.

Head-Up Swimming

If an athlete swims with a head-up position, this will lead to the athlete curling their neck upwards, putting many shoulder and neck muscles in improper positions. Many masters swimmers and some age-group swimmers still use this head position, impairing their strength and putting their shoulder muscles at risk for injury.

Solution: Focus on swimming with your head down, try looking at the bottom of the pool or only slightly in forward. Invest in a snorkel and practice having the swimmer have the water line just above their hair line.

Armpit Breathing

Every coach knows the armpit breather. This indentured swimmer has difficulties controlling and timing their neck rotation. These swimmers will often look back when they breathe or breathe late. This can irritate the shoulder by stretching and putting the shoulder muscles at the wrong muscle length.

Solution: Instruct the swimmer to initiate their breath just prior to their arm on the same side exiting the water. For example, if you are breathing to your right, initiate your breath just prior to your right arm exiting the water. Also, focus on a rapid inhale and exhale, allowing the head to return to the water rapidly. Performing six kick rotational drills with the swimmer’s arms at their side can help the swimmer learn how far and in what direction to turn their head.

Overtaking or Catch-Up

Although the catch-up stroke is commonly performed, this position of elongated shoulder flexion
aides to approximately 70% of shoulder impingements [likely primary impingements] (Yanai 1966). Extended time in this stretched out position minimizes the subacromial space and increases rubbing of the rotator cuff muscles, a major injury risk.

An example of a "catch-up" stroke.
Solution: Have the swimmer enter their hand at a ~45 degree angle, with their hand traveling down, instead of parallel to the floor of the pool.

Wide Catch

A wide catch typically embodies vigorous and excessive shoulder abduction while internally rotating the humerus increases shoulder stress (Yani 1966).

Solution: Instruct adduction of the humerus during the initial catch, ensuring the hand is not moving outside the body line.


Other Strokes Biomechanics

This is mainly a piece regarding freestyle, but here are some quick tips for other strokes. If you are interested in more detailed biomechanical adjustments for other strokes, please comment below.

Backstroke

Swim with a wider stroke, like you have your arm around your friend's back, not underneath your body.

Breaststroke

Outsweep with your hands flat or parallel to the bottom of the pool. Do not rotate your arms inward during the catch, having your thumbs face the bottom of the pool.

Butterfly

Initiate the catch earlier, do not press the chest down with the arms remaining elevated, see this piece by Dr. Rod Havrulik

Swimmer's Shoulder Return to Swimming Program

Once swimming biomechanics are improved (via coaching, drills, underwater video, and/or concentration), it is necessary to have guidelines for return. Here are the nuts and bolts for returning to swimming in no time.

No more than 3

Knowing the pain level of a swimmer is important for determining when the swimmer should return to the pool. A pain scale of 0 to 10 is commonly used, with 0 representing no pain and 10 representing unrelenting pain. For discussion of shoulder pain, we will assume that the swimmer has at least a level of 1/10 pain. The typical presentation of shoulder pain is a swimmer with pain only during swimming. Their pain level is typically 0/10 at rest. However, once they start swimming, it is likely their pain level will steadily increase. The 'No more than 3' rule allows a swimmer to maintain their “feel” for the water, until the pain level reaches a 3/10.

It is unrealistic to expect any swimmer with a history of shoulder pain to jump in the pool and have
0/10 pain. The 'no more than 3' rule allows the swimmer to swim until they reach a 3/10 pain level. This rule is based on the belief that 0/10, 1/10, or 2/10 pain is not causing more injury or inflammation. However, if a 3/10 pain level is reached, it assumes more irritation, damage, and inflammation will ensue. When the pain reaches 3/10, the first pain plateau, changes to the swimming routine need to be made. Once a 3/10 pain level occurs, it is best to rest and allow the shoulder irritation to dissipate. This is accomplished by having the athlete kick on their back with fins, eliminating arm movements and stress to the shoulder (with streamline unless this prevents resolution of the 3/10 pain level. If pain persists in streamline, move to the arms next to the body). Hopefully a swimmer’s pain will not reach between a 4/10 and 7/10 while in the pool, because they will have stopped at the 3/10 level and proceeded with directions on how to adjust their practice routine.

If you have a shoulder injury, be excited for fin kicking!
If the swimmer has a 3/10 or greater pain at rest, it is best to have them stay out of the water, it is likely the cause is inflammation or sympathetic pain. If this is the case, it is recommended to see a health care professional for treatment and further evaluation.

This approach is effective when the athlete is seeing a health care professional on a regular basis and their symptoms are continually improving. If the symptoms are not improving with a rehabilitative specialist, either find a new one or consider taking a break from doing the activity which causes the symptoms (likely stroking). As much as I realize maintaining “feel” is important, keeping a swimmer’s shoulder away from the knife of surgery is even more important.

Solution: Have the swimmer swim the typical workout until their symptoms reach 3/10. Once a 3/10 occurs, have them kick on their back with their arms at their side or in streamline (if their symptoms don't increase with streamline) with fins when their symptoms reach 3/10. This allows them to stay in the water and keep “feel” while minimizing shoulder stress. Moreover, most swimmers can do main sets and intervals with fins, keeping them involved in practice and their face in the water. If they have 3/10 symptoms prior to practice, discontinue for the day and have them seek treatment for inflammation or sympathetic pain.

No Kickboards

Kickboards are recommended if someone has shoulder pain. Most cases of shoulder pain occur due to repeated overhead motions, leading to musculoskeletal pain. Holding a kickboard for a stagnant period is locking the arm in an overhead position and irritating the shoulder repeatedly (Pollard 2001). Moreover, athletes commonly push their shoulders down on the board, leading to overpressure on the joint, a hazardous move.

Kickboards will perpetuate the pain and is easily replaced with the swimmer kicking on their back. In fact, to prevent this dangerous position and prevent re-injury, I will have swimmers kick without a board for an extended period after the symptoms resolve (approximately one month).

Solution: Kick on your back in streamline if symptoms are less than 3/10; if symptoms are greater than 3/10, have them kick on their side or with their arms next to their side.

No Paddles

This is a tough one for some programs, but paddles place higher stress on the shoulder by allowing the swimmer to grab more water (Pollard 2001). This obvious statement supports the fact that moving more water requires more arm strength and use of shoulder muscles. Even with perfect technique, paddles will increase shoulder stress, which is bad for shoulder pain. Removing paddles will give the shoulder time to recover, getting them back to paddles sooner.

Solution: Discontinue pulling until symptoms have fully resolved for at least one month. 

Bottom Hand

When coming off a flip turn, the swimmer should initiate their pull with their bottom hand. This is biomechically advantageous to rapidly rotate and spiral the athlete to the surface. Unfortunately, this powerful stroke is always performed by the same arm as swimmers are robotic. For athletes with shoulder pain, it is necessary to give the overworked shoulder a break. In almost all overuse injuries the bottom hand off the turn is the injured shoulder.

Solution: Reverse your rotations off the wall and start your stroke with your opposite arm. This will feel like writing with your opposite hand, but will distribute shoulder stress and allow adequate shoulder healing. Another option is starting your stroke with your top hand.

Proper Pacing

During times of stress, the body adapts. At the end of a race, the body adapts to finish. Unfortunately, these adaptations are often inefficient and hazardous. At the end of a 100-m race (when the swimmers slowed ~7.7%), their biomechanics shifted from using more adduction to more shoulder internal rotation. This adaptation will increase shoulder stress and risk of injury.

Solution: Attempt to even split your races and sets during practice. This minimizes the amount of time undergoing poor, injurious biomechanics.

Snorkel

Recent research suggests that swimmers with shoulder pain have higher neck muscle activation during overhead movement outside of the pool. It is hypothesized, that if the neck muscles are overactive on land, then in the water they must be even more active. Neck rotation and breathing uses the neck muscles and can feed into the increased neck muscle activation. Using a snorkel will minimize head rotation and neck muscle activation.

Solution: Consider using a snorkel during workouts if your symptoms persists.


Return to Swimming Yardage

Knowing how much yardage to begin with is difficult. I often suggest starting with 1,000 yards of breast and freestyle. Once again, if pain increases past a 3/10, I suggest kicking on your back with fins until it returns to a 0-1/10. After this, I suggest adding 500 - 1,000 yards every 3 days with a maximum of 1/10 pain. Once you're able to swim 3,000 yards, I suggest adding butterfly and backstroke (ideally on separate days, to know which is the irritant). 

Example 6 Week Return to Swimming Program

Below is an example 6 week return to swimming program, she swam once a day, six times per week, for the entire six weeks. The swimmer also did not perform any meets during this six weeks. 

The swimmer had infraspinatus tendinits initially and she received 2x/week of physical therapy for the entire 6 weeks. 

DayYardageStrokesHighest Pain LevelNotes
11000Free3
21000Free2
31000Free1
41000Free1
51000Free1
62000Free2
72000Free, Breast5Performed 1,700, then kicked 300.
81750Free, Breast2
92000Free1
102000Free1
112000Free, Breast0
122500Free, Breast0
133000Free0
143000Free, Breast, Back0
154000Free, Breast, Fly7Performed 3000, then pain during fly. Kicked last 1000.
164000Free, Breast, Back3
174000Free, Breast, Back3
184000Free, Breast, Back2
194000Free, Breast, Back1
204000Free, Breast, Back1
214000Free, Breast, Back1
225000Free, Breast, Back0
235000Free, Breast, Back0
245000Free, Breast, Back0
255800All Strokes4Perforemd 4800, pain during fly. Kicked last 1000.
266000All Strokes2
276000All Strokes2
286000All Strokes2
296000All Strokes1
306000All Strokes1
316000All Strokes1
327000All Strokes1
337200All Strokes0
347400All Strokes0
356900All Strokes1
367100All Strokes0
377200All Strokes0
387400All Strokes0

As you see, there were days when the pain exceeded 3/10. This is expected as recovery from an injury isn't linear. Nonetheless, sticking with a plan, which emphasizes rehabilitation (ideally with skilled physical therapy), progressive addition of swimming volume and strokes, and biomechanical adjustments can enhance the recovery a swimmer's shoulder. Ensure all these for a quick and long-lasting swimmer's shoulder recovery and be a life-long swimmer (#fist pump)!

References:

  1. Yanai, T., & Hay, J. G. (1966). The mechanics of shoulder impingement in front-crawl swimming. Medicine and Science in Exercise and Sports, 28(5), Supplement abstract 1092.
  2. Suito H, Ikegami Y, Nunome H, Sano S, Shinkai H, Tsujimoto N. The effect of fatigue on the underwater arm stroke motion in the 100-m front crawl. J Appl Biomech. 2008 Nov;24(4):316-24.
  3. Pollard B. The prevalence of shoulder pain in elite level British swimmers and the effects of training technique. British Swimming Coaches and Teachers Association; 2001.
  4. Spigelman T, Sciascia A, Uhl T. Return to swimming protocol for competitive swimmers: a post-operative case study and fundamentals. Int J Sports Phys Ther. 2014 Oct;9(5):712-25.

The COR Swimmer's Shoulder System E-book and video database starts with a comprehensive e-book that guides you through Mullen's four-phase system. This book details everything about the shoulder, why swimmers are at risk for shoulder pain, to which training frequency option you should choose to exactly how you can make effective program modifications if you don't have specific equipment at your disposal.


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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.

Dolphin Kicking

Take Home Points:
  1. Elite swimmers may not use a symmetrical dolphin kicking strategy.
The undulatory underwater sequence, dolphin kick, is one of the most important but unexplored phases in competitive swimming. Swimmers use this kick for butterfly and starts/ turns in freestyle and backstroke.

Unfortunately, we still have a lot of questions regarding the effectiveness of underwater kicking, as well the ideal kicking biomechanics.

In the past, I've written a lot about dolphin kicking. In these posts, I've discussed ideal depth, as Marinho (2009) looked at drag coefficients at different depths.

I've also discussed ideal kicking tempo, referencing great work by Coach Bob Gillett and Russell Mark, as well as Cohen (2012). Coach Gillett has analyzed elite male and female swimmers and suggests both groups should have a kicking tempo around 0.45 (Gillett 2013), where Russell Mark (2012) notes a tempo around 0.40 is utilized. Many feel this kicking tempo is extremely fast, but one study by Cohen (2012) indicates faster kicking tempo is correlated with net higher streamline force.

Russell Mark has even analyzed the amount of kicks by elite swimmers, noting the following kick number and time.

I've  also discussed the importance of dolphin kicking with Scott Colby, in his "pseduo-study" or elite youth swimmers, finding the 5-meter streamline, the range (depending on age) of the top times was 2.3-3.1 for boys and 2.7-2.8 for girls. For 15-Meter Dolphin Kick the ranges were 6.1-6.9 for boys and 7.1-7.3 for girls.

In another case, I've broken down a case study of dolphin kicks:

"Case Study #1

You have a 5"2" 16-year old female swimmer who goes :58 100 back and is known for her good underwaters. Her results from the aforementioned test were:
  • 0-5 m: 2.8 seconds
  • 0 - 15 m: 8.0 seconds
  • Kick Count: 16 kicks
  • Kick Tempo: 0.35
Intervention: This is a clear case of a swimmer who performs too many kicks to 15-m. For her, changing her tempo isn't needed, as high tempos are correlated with kicking speed, but instead decreasing her kick total by encouraging her to follow through her kick was advised. "Short kicking" and not following through prevents a full activation of her quadriceps and impairing forward propulsion. She was challenged to progressively decrease her kick total from 16 - 12 kicks over the course of several weeks, not progressing until she mastered her new kick count at the same or faster pace which would be tested at frequent underwater kicking tests.

Case Study #2

A 6'1" 15-year old male swimmer who goes a :49 in the 100 back. His results were:
  • 0-5 m: 2.7 seconds
  • 0-15 m: 8.2 seconds
  • Kick Count: 12
  • Kick Tempo: 0.75
Intervention: It is clear he has too slow of a tempo. However, simply giving him a 0.4 tempo will discourage and potentially impede progress. Instead, gradual increases in tempo is necessary during progression, increasing 0.05 after mastery during kicking trials.

Swimming Science has also had the opportunity to talk with some of the great minds in research of dolphin kicking Ryan Atkinson and Marc Epilot.

Dr. Epilot breaks down top speed from pushing off the start, 1.9 - 2.2 m/s and when to begin dolphin kicking. He also discusses three errors in dolphin kicking:
"To my point of view, there are 3 main mistakes that swimmers, even top athletes, do. First of all, many swimmers initiate or try to initiate underwater kicking way to soon. As I said a bit before, such mistake has huge consequences on swimmer’s efficiency. Moreover those swimmers don’t even know that they start kicking so early. They are sure to have a long and efficient gliding phase, while they start kicking immediately after water entry.

A second common mistake is to produce to large kicking movements. During a long time, trainers thought that swimmers had to push on the water with their feet, underwater propulsion being the result of that action on the water (Action-reaction Newton law). An increasing number of studies, made on different mechanical simulations, on fish swimming, or on swimmers, have shown that underwater propulsion is mostly explained by a mechanism, named the formation of a reverse Street of Karman Vortices located in the trailing edge of the swimmer. Those vortices create a backward ejection of water that leads to project the swimmer frontward. To create a coherent and propulsive street of Karman vortices, swimmers have to adjust their amplitude/Frequency ratio; usually by decreasing the amplitude and increasing the frequency.

The third mistake I would point out is the undulatory movements of the trunk and arms. In many swimmers, we can observe that their whole body is undulating, which has deleterious effects on the propulsive efficiency. The upper part of the body has to stay streamlined not to absorb the energies produce by the lower limbs. Moreover swimmer’s upper limbs have to be aligned to the orientation of his path. If the swimmer is swimming under the water straight forward, his upper limbs have to stay horizontal. If the swimmers is returning to the water surface with an angle of 30°, his upper limbs have to be at 30° regarding to the horizontal."

Ryan Atkinson mainly discussed symmetry between the downkick and upkick. He said: "Symmetry between downkick and upkick phases is highly related to high UDK velocity, and

swimmers who are more effective at the upkick phase tend to have a faster UDK velocity. Specific movements that are highly related to faster UDK are: greater peak vertical toe velocity during the upkick phase, reduced upkick duration, and less knee flexion at the end of the upkick/start of the downkick."

He also stressed the importance of "reducing the amplitude of the UDK, especially at the upper body segments (torso, head and arms) and increasing kick frequency. Particular attention should be placed on maximizing toe velocity during the upkick and limiting the duration of the upkick. Similarly with beginners, swimmers should be encouraged to recruit the muscles of the posterior chain without excessive lower back flexion or knee flexion. This can be advanced on the land by performing single leg lifts in a plank position, paying close attention to recruiting the gluteal muscles for leg lifts and keeping the hips level."

Ryan Atkinson's work feeds directly into the topic today. The results are somewhat contradictory to Ryan's statements, nonetheless a very important topic and discussion point.

The aim of this research study was to demonstrate the formation and interaction of forces near the swimmer’s body and in the swimmers wake during the dolphin kick in hopes of finding energy-saving mechanics.

What was done

A female swimmer with a 200-m butterfly time of 2:12.0 was selected. Her body was scanned with a 3D laser and subdivided into joints of the arms, torso, upper legs, lower legs, and feet. The swimmer underwater kick from a push was recorded and analyzed

Results

Maximum thrust was generated during the down kick, and was approximately twice the maximum
thrust recorded for the up kick. Both maximum values were reached at the instant when stroke velocity was at its highest within the kick cycle. The results indicate a slight increase in propulsion of 8% over the six cycles. Maximum drag was during an active dolphin kick, 208 N (~46 lbs), and at the same speed drag was ~16 N (~3.6 lbs) during the gliding motion.

Transitioning from the gliding phase to the first kick cycle creates two vortex structures, an upstroke (upper ring) and a downstroke (lower ring). Theses vortexes are shed into the swimmers wake at the end of each cycle. These forces grow in size and strength with each cycle, with cycle 6 demonstrated larger values than cycle 2 of the underwater dolphin kick.

Discussion

Optimum performance was only reached after a number of kick cycles. The dynamic drag force was ~12x higher during the kick than during the gliding phase. The mean drag and mean propulsion in cycle 6 were about 8% higher than those in cycle 2 of their dolphin kick. During the kicking cycles, the vortex created was recaptured along the body’s surface to a position where the feet would hit the vortex with the next kick

Practical Implications

Additional research is needed, but this case study shows that optimum performance was reached after 6 kick cycles, in which propulsion forces reach a constant value. This 8% increase may be explained by vortex recapturing; which may be increased with fine-tuning of body kinematics off the wall/turn.

Overall, the results are somewhat conflicting towards Ryan, but not really. Although this swimmer demonstrated a much stronger downkick, we don't know if a more symmetrical kick would improve this swimmer's dolphin kicking velocity. Looks like we need more research!

Reference:


  1. Pacholak S, Hochstein S, Rudert A, Brücker C. Unsteady flow phenomena in human undulatory swimming: a numerical approach. Sports Biomech. 2014 Jun;13(2):176-94. PubMed PMID: 25123002.
  2. Marinho DA, Reis VM, Alves FB, Vilas-Boas JP, Machado L, Silva AJ, Rouboa AI. Hydrodynamic drag during gliding in swimming.J Appl Biomech. 2009 Aug;25(3):253-7.
  3. Cohen RC, Cleary PW, Mason BR. Simulations of dolphin kick swimming using smoothed particle hydrodynamics. Hum Mov Sci. 2012 Jun;31(3):604-19. doi: 10.1016/j.humov.2011.06.008. Epub 2011 Aug 12.
  4. von Loebbecke A, Mittal R, Fish F, Mark R. A comparison of the kinematics of the dolphin kick in humans and cetaceans. Hum Mov Sci. 2009 Feb;28(1):99-112. doi: 10.1016/j.humov.2008.07.005. Epub 2008 Nov 4.
  5. von Loebbecke A, Mittal R, Fish F, Mark R. Propulsive efficiency of the underwater dolphin kick in humans. J Biomech Eng. 2009 May;131(5):054504. doi: 10.1115/1.3116150. 
  6. von Loebbecke A, Mittal R, Mark R, Hahn J. A computational method for analysis of underwater dolphin kick hydrodynamics in human swimming. Sports Biomech. 2009 Mar;8(1):60-77. doi: 10.1080/14763140802629982.
  7. B. Gillett Underwater Kicking and Foil Movement Personal communication. 2013 February 24.
  8. M. Russell Dolphin Kicking. USA Swimming. 2012 April 12.
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.