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Swim Energy Usage


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

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Finger Positions in Swimming

It is estimated 85% to 90% of propulsion generation in water is created by the application of force by an arm (Descholdt 1999; Hollander 1988). Studies have suggested the order of propulsion is greatest by the hand, followed by the forearm, then the shoulder (Miller 1975). In fact, the hand is believed to created 2.5 times the hydrodynamic force as the forearm (Miller 1975).

Now, many still debate specific stroke biomechanics and the true role of propulsion in freestyle. No matter your stance, it is hard to deny certain joint angles change during freestyle to diminish drag and maximize propulsion. For example, the shoulder joint goes through various angles of abduction, flexion, and adduction for ideal performance.

The ideal position of the fingers  for creating force has been studied previously.  Marinho (2010) used computational fluid dynamics (CFD) and noted swimming with the fingers spread produced more force and with the fingers together (see Finger Spread and Propulsion). More recently, Bilinauskaite (2013) performed similar CFD analysis and noted the largest mean of drag force was noted in the thumb adducted (see figure-1) group during the pull phase. Yet, the other hand positions had larger mean drag force during the push phase.


Bilinauskaite (2013) study suggests the finger changes drag coefficients during different phases of the stroke. However, coaches rarely discuss changing finger position throughout the propulsive phase of freestyle.

Many argue CFD analysis is not applicable to real-life swimming and using the CFD of one elite swimmer is far from perfect, but but the idea of dynamic finger positions during the propulsive phase must be considered.

Practical Implication
Differently phases of the stroke require higher or lower drag for optimization. Swimmers should consider altering their finger position throughout their stroke to maximize propulsion and drag during the stroke. Specifically, during the initial catch, a thumb adducted position during the entry until the catch phase occurs, then a transition to finger spread and thumb abduction should be considered.

However, altering finger position and propulsion surfaces must be directed in the correct position. Therefore, these subtle adjustments are only beneficial for swimmers with correct joint positioning.

  1. Bilinauskaite M, Mantha VR, Rouboa AI, Ziliukas P, Silva AJ. Computational Fluid Dynamics Study of Swimmer's Hand Velocity, Orientation, and Shape: Contributions to Hydrodynamics. Biomed Res Int. 2013;2013:140487. doi: 10.1155/2013/140487. Epub 2013 Apr 9.
  2. J. V. Deschodt, L. M. Arsac, and A. H. Rouard, “Relative contribution of arms and legs in humans to propulsion in 25- m sprint front-crawl swimming,” European Journal of Applied Physiology and Occupational Physiology, vol. 80, no. 3, pp. 192– m199, 1999.
  3. A. P. Hollander, G. de Groot, G. J. van Ingen Schenau, R. Kahman, and H. M. Toussaint, “Contribution of the legs in front crawl swimming,” in Swimming Science V, B. E. Ungerechts, K. Reischle, and K. Wilke, Eds., pp. 39–43, Human Kinetics Publishers, Champaign, Ill, USA, 1988.
  4. D. I.Miller, “Biomechanics of swimming,” in Exercise and Sport Sciences Reviews,H.Willmore and J. F. Keogh, Eds.,pp. 219–248, Academic Press, New York, NY, USA, 1975.
  5. D. A. Marinho, T. M. Barbosa, V. M. Reis et al., “Swimming propulsion forces are enhanced by a small finger spread,” Journal of Applied Biomechanics, vol. 26, no. 1, pp. 87–92, 2010. 
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. He is the founder of Mullen Physical Therapy, the Center of Optimal Restoration, head strength coach at Santa Clara Swim Club, creator of the Swimmer's Shoulder System, and chief editor of the Swimming Science Research Review.

Brief Swimming Review Volume 1 Edition 1

In an attempt to improve swimming transparency, a brief swimming related literature review will be posted on Saturday. If you enjoy this brief swimming review, consider supporting and purchasing the Swimming Science Research Review.

All 200-m strokes Result in Similar Inspiratory Muscle Fatigue
Inspiratory muscle fatigue (IMF) has been suggested as a contributor to fatigue in swimming. Now, Lomax et al (2013) have concluded IMF is similar across the four competitive strokes during a 200-meter race.

"Inspiratory muscle fatigue was evident after each 200-m swim (p < 0.05) but did not differ between the 4 strokes (range 18-21%) ... These results demonstrate that IMF occurs in response to 200-m race-paced swimming in all strokes and that the magnitude of IMF is similar between strokes when breathing is ad libitum occurring no less than 1 breath (inhalation) every third stroke (Lomax 2013)."

Remember, breathe as much as you want, as long as it doesn't increase your energy expenditure and/or impede your horizontal velocity. Want some weekend reading?

Breathing and Swimming

Breathing During Swimming
Optimizing Breathing Patterns
Breathing in Swimming

Inspiratory Muscle Training
All You Need to Know About Inspiratory Muscles Part I
All You Need to Know About Inspiratory Muscles Part II
All You Need to Know About Inspiratory Muscles Part III

Swimming Warm-down; Land Warm-down
Lomax (2013) has been busy! Another study suggest either coach or individual based swimming warm-down reduces blood lactate greater than land based warm-down. 

"The results of the present study suggest that it does not matter whether a self-paced continuous steady rate swimming velocity or a swimming recovery consisting of various strokes, intensities, and rest intervals is adopted as a recovery activity. As both swimming recoveries removed more blood lactate than the land-based recovery, swimmers should therefore be advised to undertake a swimming-based recovery rather than a land-based recovery (Lomax 2013)".

'Perfect' Swimming Warm-down

Body Size and Glide Efficiency
Body size and gliding efficiency are commonly associated in swimming. Glide efficiency is essential, as drag is the largest inhibitor of horizontal velocity aka the more drag, the slower you go! In this study, 

"[e]ight male and eight female swimmers performed a series of horizontal glides at a depth of 70 cm below the surface. Glide efficiency parameters were calculated for velocities ranging from 1.4 to 1.6 m/s for female swimmers (and at the Reynolds number of 3.5 million) and from 1.6 to 1.8 m/s for male swimmers (and at the Reynolds number of 4.5 million) (Naemi 2013)".

The results suggest:

"glide coefficient was significantly correlated to the chest to waist taper index for both gender groups. For the male group, the glide coefficient correlated significantly to the fineness ratio of upper body, the chest to hip cross-section. For the female group the glide coefficient had a significant correlation with the waist to hip taper index. The findings suggested that gliding efficiency was more dependent on shape characteristics and appropriate postural angles rather than being dependent on size characteristics (Naemi 2013)."

Instead of body size ratios may be more important for swimming speed. However, analysis of these parameters during actual swimming, not gliding are necessary before recommendations are warranted. 


Added Resistance Does Not Alter Freestyle Biomechanics?
Previous work (Maglischio) has suggested added resistance to swimming alters biomechanics. In this study,

"[e]ight female swimmers swam 25 m with maximal intensity, with and without added resistance. A bowl with a capacity of 2.2, 4 and 6 L was used as low, moderate and high added resistance, respectively. The underwater motion of the swimmer's right hand was recorded using 4 cameras (60 Hz) and the digitization was undertaken using the Ariel Performance Analysis System (Gourgoulis 2013)."

Gourgoulis 2013 indicated added resistance does not alter the velocity of the hand, pitch of the sweepback angles, and magnitude of drag or lift. 

Despite this, more research is indicated as Dr. Rushall suggested in a article review:
"[w]hether or not the change in force direction offered by resisted swimming does beneficially influence free swimming needs to be assessed."

Elite Swimmers Deficient in Zinc
Zinc is an essential mineral in the body. Yet, evidence out of San Pablo Brazil indicates elite swimmers may have a deficiency in Zn, noted by the low Zn hemoglobin levels (Giolo De Carvalho 2013).

Having appropriate levels of minerals in the hemoglobin (and potentially the cells, yet testing is still too preliminary) is essential. Low Zn can result in an impaired immune system and alter motor control

Vertical Buoyancy is Unimportant!  
Barbosa (2012) looked at the correlation between vertical buoyancy and the prone gliding test and swimming velocity. The results found vertical buoyancy was unrelated to any swimmer parameters, but the prone gliding test had correlation between all the swimming variables analyzed except horizontal velocity!

Remember, static positional gliding (with or without horizontal velocity) are far from swimming! This is likely why these positions have little correlations with horizontal velocity.

Power Training Does Not Improve Youth Men Swimming Performance
The role of strength training in swimming is a never ending debate. However, a recent study looked at power training (circuit training in my eyes) and swimming success and noted no improvements in swimming following this type of training (Sadowski 2012). 

However, these 14-year-old boys did have an improvement in tethered swimming...but is this important?

Also, Exhaustive Resistance Training Alters Joint Biomechanics, keep this in mind when designing an appropriate dry-land program. If you need some direction, check out COR's team consulting.

Catch Phase is a Static Motion?  
During an isometric contraction, muscles typically contraction on each side of the joint (co-contraction) which prevents movement. A recent EMG study found in swimming, the catch phase resulted in similar levels of contraction in the elbow flexors and extensors suggesting an isometric contraction (Lauer 2013).  Remember, the body moves past a stable arm, at least this is what this implies.

That is it for today, enjoy Women's NCAA and if you like this review, leave a comment!

  1. Lauer J, Figueiredo P, Vilas-Boas JP, Fernandes RJ, Rouard AH.Phase-dependence of elbow muscle coactivation in front crawl swimming.J Electromyogr Kinesiol. 2013 Mar 9.
  2. Sadowski J, Mastalerz A, Gromisz W, NiŸnikowski T.Effectiveness of the power dry-land training programmes in youth swimmers.  J Hum Kinet. 2012 May;32:77-86. doi: 10.2478/v10078-012-0025-5. Epub 2012 May 30.
  3. Barbosa TM, Costa MJ, Morais JE, Moreira M, Silva AJ, Marinho DA.
    How Informative are the Vertical Buoyancy and the Prone Gliding Tests to Assess Young Swimmers' Hydrostatic and Hydrodynamic Profiles? J Hum Kinet. 2012 May;32:21-32. doi: 10.2478/v10078-012-0020-x. Epub 2012 May 30.
  4. Giolo De Carvalho F, Rosa FT, MarquesMiguel Suen V, Freitas EC, Padovan GJ, Marchini JS. Evidence of zinc deficiency in competitive swimmers. Nutrition. 2012 Nov-Dec;28(11-12):1127-31. doi: 10.1016/j.nut.2012.02.012.
  5. Gourgoulis V, Aggeloussis N, Mavridis G, Boli A, Kasimatis P, Vezos N, Toubekis A, Antoniou P, Mavrommatis G. Acute effect of front crawl sprint resisted swimming on the propulsive forces of the hand. J Appl Biomech. 2013 Feb;29(1):98-104.
  6. Naemi R, Psycharakis SG, McCabe C, Connaboy C, Sanders RH. Relationships between glide efficiency and swimmers' size and shape characteristics.J Appl Biomech. 2012 Aug;28(4):400-11. Epub 2011 Nov 14.
  7. Lomax M. The effect of three recovery protocols on blood lactate clearance after race-paced swimming. J Strength Cond Res. 2012 Oct;26(10):2771-6.
  8. Lomax M, Iggleden C, Tourell A, Castle S, Honey J. Inspiratory muscle fatigue after race-paced swimming is not restricted to the front crawl stroke. J Strength Cond Res. 2012 Oct;26(10):2729-33.
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. He is the founder of the Center of Optimal Restoration, head strength coach at Santa Clara Swim Club, creator of the Swimmer's Shoulder System, and chief editor of the Swimming Science Research Review.

High Stroke Rate for Elite Sprinting?

"Some people don't have the guts for distance racing. The polite term for them is sprinters."
"The East Germans first used biomechanics. This meant that rather than guessing about technique and form, they could apply changes to athletic performance based on science."
-Bill Toomey

In swimming, proper biomechanics are essential for success. Yet, the biomechanical factors that affect success are numerous and vary between people. An individual stroke is influenced by: anthropometry; range of motion; aquatic signature (level of buoyancy and balance); level of anxiety when first introduced to the sport (survival instinct); natural strength and developmental environment (Skinner 2012). A few studies have tried to find objective factors associated with success, but the only association was age (Saavedra 2010; Variables Predicting Performance in Young Swimmers).

In a more recent study, handgrip strength was related with 100-meter freestyle success in female swimmers.

Another variable influencing stroke biomechanics is race distance. On Swimming Science, we've discussed potential differences in sprint swimming biomechanics, specifically regarding head position.

In track, running speed depends on stride length x stride frequency. In swimming, stroke length x stroke frequency is also associated with success, but unlike track, the items which compose these factors are much more complex. In sprint track, Usain Bolt is a dominant and unique athlete. He is on average 4 - 5 inches taller than other sprinters, which allows him to run his 100-meter sprint much differently than other Olympic 100-meter runner, as Usain uses a higher force production and stride length, but a lower stiffness and stride rate.

Despite the huge differences between running and swimming, I feel some comparison is possible, especially the correlation between force production, stroke length, and stroke rate.

Dr. Havriluk, President of Swimming Technology Research, has studied total force production in elite swimmers using the Aquanex ,a pure measure of force production, not specifically horizontal force. This difference is important as overall in-water force production is highly dependent on the direction of force.

SUBJECTSVPF leftPF rightSR cycles/secSL m/cycleHT inWT lbs

It is well accepted sprinters have a higher stroke rate, but what is the difference between elite sprint swimmers? If the applications of running are similar, than height would be correlated with Olympic success likely has a higher force production, greater stroke length, lower stroke frequency and a lower muscle stiffness, increasing the ability to store and release energy production.

Sprinters often have a higher capacity to produce power. In swimming, propulsion is generated mainly through the arms. Swimmers generate propulsion by orienting their propelling surface (hands, forearm, upperarm) as perpendicular to the water as possible. However, many associate stroke rate and frequency with sprint success, but Usain Bolt, the fastest man alive, has a higher ground reaction time, greater force production, and lower stride rates. Do taller elite swimming sprinters have a longer catch time, which generates higher force production, but a slower stroke rate?

Below are the number of strokes for the last 15 meters compared to athletes height in meters in the Men's 50 free from London. As you see the dots are not linear, but scattered. This appears, height and stroke frequency are not associated in the last 15 meters in elite sprinters. However, this does not answer the main question since height and stroke length aren't always correlated. Moreover, time and stroke rate don't always correlate either.

As you see, the overall time (wish I had actual 15-meter times) and stroke amount also shows a very weak correlation. This data is not very helpful in finding answers about the relationship between stroking parameters in sprint events, as horizontal force production, arm length, stroke rate, and speed are other variables that need further individual analysis. However, is too much to speculate sprint swimming has a Usain Bolt around the corner? Or did we already have a Usain Bolt (Popov's historic technique)?

Too often, sprinters are taught and instinctively perform a high stroke rate. This may result in sprinters rushing their catch and producing inadequate force. Individual information is essential for these elite sprinters, because an outlier like Usain may exist, but they might be rushing their stroke, poorly catching water, taking excess strokes, and fatiguing early. This individualized stroke biomechanics essential, as a swimmers strengths must be maximized. Unfortunately, many coaches are unable to visually quantify force production. This requires more specific testing and research on the subject, where objective measures dictate stroke modifications. Make sure you're making the correct adjustments, with objective, not subjective information.


  1. Taylor MJ, Beneke R.Spring mass characteristics of the fastest men on Earth.  Int J Sports Med. 2012 Aug;33(8):667-70. Epub 2012 Apr 17.

By G. John Mullen founder of the Center of Optimal Restoration, head strength coach at Santa Clara Swim Club, creator of the Swimmer's Shoulder System, and chief editor of the Swimming Science Research Review.