Swimming Energy Calculator

OttrLoggr: Energy Use Calculator

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

Total Cost

Quick Food Reference

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Are you Training the Phosphagen System Enough?

People prefer straight black and white answers and exercise physiology is not an exception. Most courses in physiology focus on three different energy systems, which text books and classes typically include the following:
  1. Phosphagen: 
    1. Utilizes ATP and creatine phosphate as its primary energy to the cells.
    2. Creatine phosphate is a high energy phosphate molecule.
    3. Active at the start of all exercise regardless of intensity.
    4. Used for short term, high intensity resistance exercises (sprinting in swimming and weightlifting) 
    5. The cell needs certain types of energy present in order to get the muscles to do a specific task.
    6.  Provide ATP for high intensity activities lasting 0-6 secs (up to 20-30 secs).
    7.  In burst-like sports, utilizing creatine phosphate becomes your major source of energy 
    8. This means that most of your training should mimic these burst-like exercises to get your body to naturally perform during competition.
    9. Work/Rest ratio 1:12 to 1:20 
  2. Glycolytic:
    1. Carbohydrate breakdown to produce ATP in the cytoplasm (i.e. sarcoplasm of a muscle cell).
    2. Provides energy primarily for moderate to high intensity activities: for 30 sec up to 2-3 min of activity in a hyperoxic cellular environment. 
    3. This period in sports is recognized by periods of reduced oxygen that is available in our muscle cells.
    4. This fatigue produce large amounts of lactic acid which will be converted into energy cells.
    5. Athletes using this energy system is so great in the particular sport, that this acid build up needing a buffer to clear out.
    6. Only when an athlete can buffer this acid quickly can he or she produce more force, last longer and simply perform at a high level.
    7. It makes it imperative to train specifically in this energy system that mimics the sports energy system so the body can adapt over time.
    8.  Work/rest ratio 1:3 to 1:5.
  3. Oxidative:
    1. Provide ATP for low intensity activities lasting longer than 3 mins. 
    2. Sports like long distance swimmers, soccer, cross country and marathon runners utilize mainly the oxidative demand 
    3. An example could be if you started sprinting for 5 miles, obviously for the first 10-20 seconds you would be able to sustain a sprint, but around that 20 second mark you will slow down.   
    4. This slowing would then turn the switch from creatine phosphate to lactic acid for energy.
    5. The oxidative system by itself is used primarily during complete rest and low-intensity activity.
    6. It can produce ATP through either fat (fatty acids) or carbohydrates (glucose).
    7. Because fatty acids take more time to breakdown than glucose, more oxygen is needed for complete combustion.
    8. If efforts are intense and the cardiovascular system cannot supply oxygen quickly enough, carbohydrate must produce ATP.
    9. In very long duration activities, carbohydrates can become depleted and the body looks to fat as the energy producer.
    10. Work/rest ratio 1:1 to 1:3.

These descriptions make it seem obvious the phosphagen system is the first to fire, but quickly exhaust during any maximal effort. But, like I said, the answers aren't always straight forward. In actuality, all these energy systems fire initiate together, however, the phosphagen system is most pronounced. This simultaneous activation is different than traditional thought. 

With this in mind, one must also accept the contribution from each energy system and how long each system lasts is taken from maximal sprint cycling or running. Unfortunately, swimming gets the short end of the stick and doesn't receive much research on this topic (likely from low funding and secondly due to difficulty in measurement). Swimming is in a cooling environment which partially supports the body. This makes swimming less demanding on the body than these other modes. This means the phosphagen system likely lasts longer than most typical ground-based sports.

Second, not many races require a swimmer to maximally sprint. For instance, in the 200 free, the swimmer is at approximately 80% of maximal effort. This submaximal effort may actually prolong the stores of the phosphagen system. In other sports, intramuscular PCr stores are likely 70 – 84% replenished after 180 s of PR following a maximal sprint (Dawson 1997; Bogdanis 1995).

One must consider if someone is swimming a 200-free and swimming 80% of their maximum, how much does their PCr restore at each turn? If this restores 5 - 10% on each wall, then are you training this system enough? Moreover, the phosphagen energy system which is used first during every mode and intensity of exercise. If there is any PCr system in the body, it will be used first! 

Are you training the phosphagen system adequately?

  1. Bogdanis CG, Nevill ME, Boobis LH, Lakomy HK, and Nevill AM. Recovery of power output and muscle metabolites following 30 s of maximal sprint cycling in man. J Physiol 482 ( Pt 2): 467-480, 1995.
  2. Dawson B, Goodman C, Lawrence S, Preen D, Polglaze T, Fitzsimons M, and Fournier P. Muscle phosphocreatine repletion following single and repeated short sprint efforts. Scand J Med Sci Sports 7: 206-213, 1997.
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.

Pacing 101 for Swimmers

Pacing 101 for swimmers is an easy to follow instructional manual for pacing various swimming races. This manual only involves one strategy, as one pacing strategy is ideal for all swim races in this writer's opinion.

You may not believe a 50 and 1500-meter distance race has the same pacing strategy, but remember all that matters is who puts their hand on the wall first.

Dr. Rushall brought to light the view of poor pacing a few years back with his paper on the Future of swimming: “myths and science”. In this must-read resource, he discusses the poor ideas of pacing continually seen on pool decks. Unfortunately, going out fast, trying to hold on, and dying only lead to fatigue and what I call “Groin Kick Syndrome” is still a common strategy.
Luckily, equal pacing has become more common, most notably at the Olympics, as most great athletes don’t necessarily finish faster into the wall, but they maintain velocity, as others fatigue [To note, the start will increase velocity, which provides a believed 1.5 - 2 second advantage over the other lengths]. This was even discussed by blogger and coach Chris DeSantis in the 200 breast. I believe pacing 101 for swimmers and the new Omega Ramp Blooks were the main reason for improvements over the past two years. These likely aided in world records being approached and broken once again.

One main reason going out slower and having a more “even” pace is better than flying and dying is due to the use of creatine phosphate (CP). Many are familiar with the supplement creatine, but certain research makes this compound more intriguing than once thought.

Energy contribution from the CP system is mainly thought to last for 6 – 10 seconds at the beginning of a race, then diminish. However, studies inducing severe fatigue note CP is still present in the body, therefore CP system never shuts down completely.

Dr. Maglischo brings to light the fast and slow acting role of CP. He notes CP isn't necessarily used rapidly, if the athlete does not go out too fast early in the race. This increases the amount of CP in the body and allows longer ATP production to hold off off fatigue. Now don't get me wrong, CP isn't the only source of fatigue, as Dr. Maglischo notes:

“research on reducing the rate of creatine phosphate use during exercise, increasing its rate of restoration after exercise, and the effects of supplementation of this substance on performance, should be accelerated. Research on ways that the rates of accumulation of inorganic phosphate and ADP can be reduced, or mediated, within working muscles during exercise should also become a priority. The possibility that training may also increase their rates of removal from working muscle fibers through either active or passive metabolic procedures is also a topic worthy of study. Likewise, new training techniques that may achieve these effects should also be explored … Finally, we should not dismiss the role of lactic acid in muscular fatigue as inconsequential. After all, at the present time, acidosis has not been absolutely discredited as a cause of muscular fatigue
(Maglischo 2012)”.

As you see, pacing 101 for swimmers is becoming more common in elite swimmers. Finding a steady pace and maintaining this speed is critical for success, likely from the maintained use of the increasingly important CP.

CP isn't the only factor in fatigue, but as swimming is not against gravity, uses a cooling medium, and is rhythmic, CP can likely be used even longer than other sports. The next installment of pacing 101 for swimming discusses methods to delay the onset of fatigue.

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.

Energy Systems in Swimming

Associating energy systems with the set, workout, season, and race are essential for optimizing race performance. Most swimming races utilize multiple energy systems with an emphasis on the anaerobic system, but realize the anaerobic system is not the sole system. The amount of contribution from each energy system is essential to understand to provide the correct volume of training in these energy systems. This will provide your athlete’s with the tools to maximize race performance.

A 2004 study looked at the alterations during a 400-meter freestyle. Laffite 2004 took seven male swimmers with an average 400-meter free time of 4:15 and looked at energy system and biomechanical differences with race differences.

First they had each athlete perform a 100, 200, and 300-meter freestyle and analyzed the differences between these distances and the 400-meter freestyle. Blood lactate was significantly higher in the 400-meter freestyle compared to the other three distances. These researchers hypothesized:

"The estimated contribution of anaerobic metabolism (EsCANA) during the first 100-m and the 400-m represented 45 % and 20 % of total energy output, respectively."

The swimmers experienced a U-curve in stroke rate, starting high at the beginning of the race, decreasing, and then increasing at the end. On the other hand, stroke length steadily decreased throughout the race.

These findings are not ground-breaking, but interesting to note the amount of total energy utilized during the race. Do you correlate the amount of anaerobic training with the race duration for your swimmers? It is important to correlate the volume of training specific to the energy systems used in the race.

This concept is more important in elite athletes with a focused stroke and race distance. Specializing youth swimmers will provide acute benefits, but potentially limit their versatility. For more information read, Anaerobic Capacity in Swimmers and Duration Specific Training: Sprints.


  1. Laffite LP, Vilas-Boas JP, Demarle A, Silva J, Fernandes R, Billat VL. Can J Appl Physiol. 2004;29 Suppl:S17-31. Changes in physiological and stroke parameters during a maximal 400-m free swimming test in elite swimmers.
By Dr. G. John Mullen, DPT, CSCS. He is the founder of the Center of Optimal Restoration, creator of the Swimmer's Shoulder System, and head strength coach at Santa Clara Swim Club.