Some thoughts on optimal swimming ‘style’ for triathletes

Alan Couzens, MS (Sports Science)

In my last post, I offered some thoughts on how the optimal running gait at Ironman pace may differ from the optimal running gait in traditional distance running events. Specifically, I highlighted that scientific investigation on the topic to date has found that the most important ‘technique’ element in maximizing economy is cadence and that stride length (& resulting ‘style’) will differ markedly between events. Finally, I brought into question teaching methods that seek to mimic the traditional ‘pretty’ run technique of high speed runners when applied to low speed events.

In this post, I’m going to investigate whether the same is true for the Ironman swimmer, i.e. should we seek to mimic those long beautiful strokes of Thorpey et al., or is there a better way?

Identifying the most economical swimming technique for an individual is a surprisingly complicated proposition. In addition to the various morphological & biomechanical factors that influence economy, there are several different types of economy or efficiency that we can measure. Are we talking about propulsive efficiency, gross efficiency or delta efficiency?

Propulsive efficiency

Propulsive efficiency is what most people think of when they think of an ‘efficient’ swimmer. It refers to how much of the swimmers movements result in forward propulsion vs those movements that are ‘lost to the water’. Huub Toussaint has done some neat studies utilizing his proprietary MAD system, which measures actual force of each swimming pull vs the ‘real world’ aquatic propulsion that comes from this force. Unsurprisingly, he has found that elite pool swimmers exhibit significantly better propulsive efficiency than elite triathletes. Elite swimmers only lose 40% of the energy that they apply to the water, while elite triathletes lose up to 55%!

This difference in the propulsive part of a pool v/open water stroke is easily visualized as the horizontal distance between when the forearm reaches vertical and purchase is made at the start of the stroke & when the forearm breaks vertical and purchase is lost at the back end of the stroke…

The figures above show that the distance between gaining the vertical forearm in the front and losing it at the back is greater with a traditional swimmer technique and less with a more circular, higher revving technique typical of a triathlete. This leads to a greater propulsive efficiency per stroke for the traditional swimmer.

Gross efficiency

Similarly, the swimmers rule when we take a closer look at gross efficiency. Gross efficiency refers to the efficiency in converting metabolic power into mechanical power. In the world of cycling, this is easily measured as the amount of metabolic energy (kilojoules or kilocalories per unit of time) vs the amount of mechanical energy produced per unit of time (i.e. watts). Typically, the gross efficiency numbers arrived at for cyclists fall in the 20-25% range. Utilizing Toussaint’s MAD system, a similar method can be used for swimmers to compare metabolic work (VO2) vs mechanical work produced. Even for the best swimmers, swimming is quite a bit less efficient than cycling as an activity, resulting in gross efficiency numbers of ~7-9%.

Again, when comparing swimmers and triathletes, swimmers take significantly less oxygen to produce the same levels of swimming power. Put another way, if we have a swimmer and triathlete with the same VO2max, the swimmer will produce significantly more mechanical power & (assuming similar propulsive efficiency) will go significantly faster at this effort level.

Delta efficiency

This begs the question, why don’t more elite triathletes swim like pool swimmers? Sure the more circular, faster revving technique offers some obvious advantages in choppy, close quarter swimming but is there more to it than that?

Returning to the world of cycling, professional cyclists have had the guys in lab coats confused for quite some time. See, the bulk of lab studies that have looked at the most efficient cycling cadence have found that a cadence of approximately 60rpm consistently results in the lowest oxygen cost for a given power output. However, we know from watching professional bike racing that elite cyclists rarely work at such a low cadence in the real world despite it, theoretically, being the most efficient. The million dollar question – why?

Ed Coyle has spent a lot of time crunching the numbers and investigating this question and he came upon a curious phenomenon. While absolute O2 cost may be lowest at low rpm, the change in O2 cost with increasing power is actually less for a higher rpm ‘style’ than a lower one. This is shown graphically below…

 

The blue line represents mechanical vs metabolic output at 100rpm, while the red represents the same relationship at 60rpm. While 60rpm is more economical at low power outputs, the difference disappears at ~400W

This difference in slope (rather than absolute O2 cost) between these 2 conditions has been termed the delta efficiency. The delta efficiency eliminates the basic (unloaded) O2 cost of the activity (200W for the 100rpm condition & 47W for the 60rpm). A practical example….

We take an athlete who uses a powertap (hub based power meter) and hook him up to a metabolic cart (VO2max test machine). We have him pedal at 200W and 90 rpm and monitor his metabolic response. Mid-way through the test, his chain breaks & (mechanical) power output drops to zero but metabolic output doesn’t. He’s spinning away, generating zero power but it’s costing him some energy.

All of a sudden he figures out what’s going on and slows his cadence. Lo and behold, his metabolic output goes down. In other words at zero watts and 90 rpm, his metabolic cost is higher than it is at zero watts and 60 rpm. If he just sat there on the bike and didn’t spin at all, his metabolic cost would be lower still. The question is, in real world athletic competition, to what extent are these non propulsive ‘spinning the pedals around’ movements limiting?

Put another way, what ultimately slows a cyclist down? Is it an inability to keep up with the high levels of whole body O2 delivery or are peripheral factors (within the muscle) the limiter? It has been argued that the limiter will vary both among different types of cyclists and among different types of events. For example, renowned sports scientist Alejandro Lucia has suggested that the difference between the high rpm climbing style of Lance Armstrong and the low rpm climbing style of Jan Ullrich was fundamentally the difference between an athlete who was ‘centrally strong’, i.e. Armstrong and an athlete who was ‘peripherally strong’, i.e. Ullrich. If we apply this back to the pool, it would be reasonable to assume that most triathletes fall on the ‘centrally strong’ side of the fence and can afford to give up a little gross efficiency in the name of delta efficiency, esp. considering the duration of their event.

This central v peripheral demands of different pedaling cadences has been investigated in a number of studies that have arrived at a similar conclusion: While absolute ‘whole body’ metabolic cost is higher in the high cadence condition, the peripheral cost within the ‘prime mover’ muscles is lower. This results in improved hemodynamics (O2 in, lactate out), decreased muscular stress, decreased metabolic stress (glycogen use) & improved peripheral endurance (e.g. Ahlquist et al., 1992, Faria, 1992, Gotshall et al., 1996, Takaishi, 1996). For example, The Ahlquist study showed 28% less total muscle glycogen used by cycling at 100rpm vs 50rpm at the same power output. The bulk of this difference was in the less economical Type II fibers, indicating less reliance on these with the high cadence approach.

Does the above also apply to swimming?

Indeed, if we analyze the data from Toussaint’s study on swimmer v triathlete economy with a view to identifying the optimal stroke length for delta v gross efficiency, we find a similar trend seems to exist in the pool, with presumably similar metabolic/peripheral consequences.

From the chart, it appears that the ‘sweet spot’ for maximizing delta efficiency in swimming is a faster revving, shorter length technique of ~0.4 x standing height, while the sweet spot for maximizing gross efficiency is a longer, more traditional technique of ~0.7x standing height. In practice, competitive triathletes split the difference and find the optimal balance between gross and delta efficiency at ~0.55x standing height. Real world stroke per length numbers for each of these conditions are shown below for different pool lengths

 

In summary, it is suggested that the optimal swimming style will vary with the absolute effort level. In events where VO2max is limiting (events in the 3-15min range typical of middle distance and distance pool events), the optimal technique will tend towards a longer stroke that maximizes pace for a given VO2 output (a stroke of ~0.7x height).  However, for longer events that are more limited by peripheral factors such as the lactate threshold or metabolic efficiency (i.e. most triathlon events), a shorter, faster rate stroke (closer to 0.55x height) may ultimately prove more economical.

Train smart,

AC.

Top 10 Action Items from the USAT Level 1 Coaching Clinic

Those of you who have seen my book collection will attest to the fact that I have a voracious appetite for the acquisition of knowledge. However, as Bruce Lee once said “Knowledge is nothing without action” and so, I have made a commitment to devote this decade of my life to transforming my core paradigm from the acquisition of information to the application of information. I went into the recent USAT Level 1 Coaching Clinic in Clermont, FL with this objective in mind and came away with some key 'action items' that I plan to apply to myself and the athletes that I work with. Hopefully, you will find some value in them too.

Before I get started, I want to take this opportunity to thank all of the presenters at the clinic. I was surprised and impressed by the depth of information presented at a level 1 event. The following key points represent a mix of almost direct quotes from the presenters with a sprinkling of concepts that, while inspired by the topics presented may run almost counter to the presenter’s opinions. I want to make it clear that these conclusions are my own and do not necessarily represent the intent of the presenter. Either way, I wish to thank Tim Boruff and Linda Cleveland of the USAT and all of the attending presenters for the many ‘light-bulb moments’ that I experienced over the course of the weekend. My top 10 'action from the weekend are presented below:

1. Know the price of your athletic goals and if you can afford them (Psychological Aspects of Coaching – Dara Wittenburg)

Unfortunately, we live in a country where the majority of individuals commit to having what they want before deciding whether they can truly afford it. In my experience, this mentality also runs over to triathletic goals. Typical first conversation with a new client goes something like this:

“I want to race Hawaii”
“OK, my current athletes at that level are doing……..”
“Sounds good, sign me up”

In other words, much like Maverick in Top Gun, committed age-group athletes have a tendency to ‘write checks that their bodies can’t cash’. It is a ‘cart before the horse’ mistake to commit to a race, a time goal, and a training load before looking at your current training load and rate of improvement to this point. Rather than the car sales showroom paradigm, where you sign off on a Hummer with all the options when all you can really afford is the used Dodge Aries on the other side of the street, you should approach the goal setting process more like a kid taking his pocket money into the candy store “OK, this is how much I have (time available, training volume to date etc), what can I buy with this?” A coach can help greatly with determining the price (based on previous experience with other athletes and data from your own logs) and giving you a reality check on what you can afford & the time it will take you to save for what you really want.


2. Have clear, written goals & a session plan for every key session that you do

Know the purpose of each of your key sessions and write down a simple action plan of the 3-5 things that you are going to focus on out there in order to achieve your bigger goals. Rather than labelling all of your sessions “training sessions”, it is sometimes better to take on the paradigm of teams sports and consider some “practice sessions”, i.e. sessions in which you have an opportunity to drill the psychological, technical and tactical objectives of preparation in addition to the physical. A big part of this is having a written “race plan” for each of your key sessions. Creativity is your only limit in how far you go in simulating the demands of your event.


3. Think like a Body Builder when planning your strength training (in fact, all of your training).
(Strength Training – Dara Wittenburg).

Those of you who have spent a good amount of time in a gym know that the serious lifters are intently aware of both the quantitative and qualitative aspects of their training and their rate of progress in each. Serious lifters know not only how many sets they plan on doing for the week, but also what load they are going to use for each exercise and if (heaven forbid), they only get 6 reps at 350lbs instead of their usual 7, tears may be shed, questions will be asked and changes will be made. This obsession with monitoring all of the variables of performance, while common in some endurance sports like swimming and track has escaped the easy-going world of triathlon. To describe and evaluate your training in terms of volume alone is only giving you part of the picture. In the gym and on the road, pay attention to both the quality and quantity of your training and change one or the other if an extended plateau occurs.

4. Apply a written training diet to your basic week
(Nutrition for the Multisport Athlete - Jennifer Hutchison, RD, LD, CSCS)

Some simple applications that every athlete should apply to their weekly nutrition plan:
4-6 small meals/day
20-30g/ lean protein at each meal (1.2-2.0g/kg/day)
Emphasize a VARIETY of colorful fruits and vegetables to supply adequate nutrients and phytochemicals & 30g of fiber per day.
Add beans or legumes to evening meal 3 to 4 times each week (not within 24hrs of key sessions/races).
Moderate or no alcohol consumption
Limit refined carbohydrates and sugar (save the refined carbs for training).
Ensure sufficient daily water intake to maintain day-to-day bodyweight.


5. Apply a written nutritional and recovery plan to all key sessions
(Nutrition for the Multisport Athlete - Jennifer Hutchison, RD, LD, CSCS)

A part of the written ‘race plan’ for your key sessions should be a clear and concise nutritional plan. Below are some points to consider:
2hrs before: 500-700ml of Sports Drink or water + low-fiber meal
15mins before: 150-300ml of Sports Drink
During: 150-300ml of Sports Drink every 15-20 minutes (60-85g/L CHO concentration + 400-700mg Na/L)
Notes:
o Get to know your sweat rate in different conditions by weighing before and after EVERY key session greater than 1hr)
o Make sure you keep optimal CHO concentration when taking Gels or Blocks by drinking ~300-500ml of pure water for each gel packet (~27g CHO)
o Note: Some athletes may require up to 1500mg/L of Sodium
· After: 1.3-1.5kg/L of bodyweight lost + 1g/kg of CHO in first 30 minutes (liquid form) and 1g/kg of CHO + 0.3g/kg of protein in solid meal within 2hrs.

6. Incorporate walk breaks in your key running sessions.
(Running Skills and Economy Training …. Lee Zohlman, B.S.)

First, a couple of key reasons to consider incorporating walk breaks in your long training runs and races.
* Nutrition & Hydration: You will get in a greater volume of fluid by not splashing it everywhere while your run. In addition, letting your heart rate drop 5-10 beats will greatly help in processing the calories. In my experience, in long runs and races, the faster finish that comes from proper nutrition and hydration more than makes up for any time lost in walk breaks
* Planned v’s necessitated walking: In the context of an Ironman and Half-Ironman/Marathon for novices-intermediate competitors, being realistic, some walking will be involved at some point in the race. The quality and speed of the walk period will be greatly enhanced if you take a proactive approach and evenly distribute them through the race, rather than dealing with the psychological blow of having to walk at the end.
* Neuromuscular re-set: Perhaps the most important reason for walk-breaks. Quick experiment for you: At the half way point in your next moderately long run take the time to do 20 deep squats and 20 lunges. I promise you, that as smooth as you were feeling in your running gait up to that point, you will notice some level of tightening of the muscles. While this tightening may not be sufficient to affect your gait in any dramatic way, the increased resistance in your stabilizers and antagonists can have a large effect on the energy cost required to maintain your desired stride length & rate, this is to say nothing of the increased risk of injury from the diminished elasticity in your antagonists and the diminished capacity of your stabilizers. In my experience, by incorporating walk breaks & even some basic drills/alternative movements during the course of your run, you will feel a noticeable difference in the ‘spring’ left in your gait at the end of a long run.

7. Get a proper bike fit w/ someone who knows bikes AND functional anatomy (and how the two work together)
(Cycling Skills and Economy - Adam Baskin, M.A.)

We are all anatomically individual in a number of ways that have direct implication on the way we pedal a bicycle. Not only are there structural variations that span the gamut, including femur length, torso length, shoulder width etc, there are also many functional differences that (should) come into play when we are looking at bike fit. Keeping in mind that a muscle is weakest when it is excessively lengthened or shortened, it is important from an efficiency perspective to maintain optimal length-tension relationships in your cycling muscles. Taken to extremes, you will even see situations where a muscle is stretched so far beyond its functional range of motion that other muscles begin to contribute in ways that they were not designed to. A prime example of this is when an athlete goes for so much drop at the front-end that they close the hip angle up so much that the lumbar extensors, instead of the hip extensors begin initiating the pedal stroke. This has all kinds of nasty implications from back strains to degeneration of the facet joints of the spine. It is also not an efficient way to pedal a bicycle, i.e. it is slower.
When it comes to an effective bike fit, adjust the bike position to preserve:
* Optimal hip angle (greatest angle of hip flexion without lumbar compensation minus a few degrees)
* Optimal knee angle (greatest angle of knee extension w/hip flexed and no lumbar/hip compensation minus a few degrees)
* Optimal ankle angle (greatest angle of ankle dorsi-flexion with no knee compensation minus a few degrees)
* Roll this position as far forward as possible within constraints of geometry and comfort.
If you don’t know what I mean by the terms listed above, go to someone who does!!

8. Incorporate swim drills for ALL 3 R’s in your weekly program.
- Rhythm
- Range
- Relaxation
(Triathlon Swimming - Bill Kuminka, MS)

Don’t become obsessed with range drills (e.g. T.I. drills) to the exclusion of rhythm and relaxation drills. Use what you need. For example, many T.I. swimmers could benefit from periodic use of rhythm and relaxation drills such as:
- Straight arm (kayak) swimming (including drills with a broomstick)
- Freestyle & Backstroke with a butterfly kick
- Head up (polo) freestyle.
- Supra-rate swimming with stretch cordz or fins.
Also don’t become exclusively obsessed with what happens in the “front quadrant”, the other quadrants count too!!
Note: Stay tuned for an upcoming article that will further explore the 3 concepts listed above.

9. Set a training program that allows you to complete 90%+ of the workouts & monitor and modify accordingly.
(Periodization Methods for Triathlon - Lee Zohlman)
Whatever training program format you choose to follow, an important metric to track is the % completed v’s planned. It is no good putting together an elaborate, periodized model with macro-this and micro-that if your predicted training volume is merely an ambitious guess. For this reason, I find it useful to build the training program from ‘the ground up’ beginning with a basic week that reflects the athlete’s current fitness and progressively building in accordance with the athlete’s individual rate of improvement from there.

10. Test yourself regularly to see what works for you and when you need to change.
(Exercise Physiology - Adam Baskin, M.A.)

In other words, it is important to know your key limiters, key objectives for improvement and specific metrics for each objective and it is important to test regularly to see if what you are doing is working. Remember that each individual is an experiment of one and the only way that you will truly know if your current training program is appropriate is to identify valid tests and use them on a regular basis (even if it means putting off getting your new disc wheel so that you can get yourself to an exercise physiology lab and get some controlled, objective data).