Optimal FV profile in sprint swimmers: more than just another marginal gain?

Unless you were too busy chasing Pokemons, you’ve noticed that the Men’s Olympic title on the 50-m freestyle was a 0.01s story. Relatively speaking, for a 21.40s effort, this is a 0.05% difference. Put that into another metric, the difference between gold and silver was about one inch, about the distance between your middle and little fingers.



We all know elite sport is a world of “marginal gains”, and among the many possible ways French swimmer Florent Manaudou and his staff could have chased this 0.05% marginal gain, my point here is that the starting block push performance could have been improved using the optimal force-velocity approach we’ve developed over the last years (see here for a reminder). Of course, many other factors could have been considered. One is having longer fingers of course. But hey, I have a hammer so sorry, I see nails everywhere…
For this story (any resemblance to reality is pure coincidence) I will take my own personal FV profile and imagine I’m an Olympic Games finalist chasing for a 0.05% margin in the Final. Note that my points here are based on scientifically validated methods and research-based evidence, not on my coach (or my own) « gut feeling and experience ».

Sprint start push-off performance in swimming

Swim start can be considered as an inclined single all-out push-off during which the swimmer must produce as much impulse as possible, so that when taking off, his body as the highest velocity possible to enter the water (in addition to an optimal diving angle). Many papers are available on this topic, an example with this review. Depending on the studies, the overall angle of push is about 25-30° (we’ll take 30° in our analysis). What all studies agree on is the fact that 50-m sprint start take-off velocity is a determinant of final performance.
So should I improve my take-off velocity through training, then my block phase performance will be better and all other things being equal, my final time will also be better. Remember I need a 0.05% improvement.

How to improve push-off performance through “optimized FV training”

Our approach based on individual assessment of the force-velocity profile and the computation of the individual optimal force-velocity profile (see here for a practical summary) shows that in theory, should my training be specifically programmed to reduce my force-velocity deficit (i.e. the gap between my actual and optimal profiles), then, my performance (take-off velocity or jump height in the case of vertical jump) should increase. This theoretical statement has been confirmed very clearly by experimental results (paper submitted, see the slides of a Congress presentation here). Briefly, in this study, subjects whose training loads and program were individually tailored to reduce the FV deficit all improved jump height, by extremely large magnitudes (by 14% on average for subjects with a 30-60% force deficit, which is ≈300 times the 0.05% I need) whereas only half of the controls did, and by lower margins. All control subjects followed the same program, working on all the spectrum of loads, from very high force to very high velocity, independently from their individual FV imbalance. A “one-size-fits-all” approach.
So below is my FV profile. The interpretation is pretty simple: I have a deficit in force (my actual FV profile (black curve) is 35% below what would be my optimal FV profile for a swimming start (pink dashed curve). Note that my actual FV profile was computed using Samozino’s method knowing jump height and total mass in a 5 or 6 loaded jumps protocol (see previous episodes and our IJSPP paper for details). It only took 20min and the scientifically validated iPhone app “MyJump”. The optimal FV profile is computed as the profile maximizing take-off velocity for a given maximal power output. Since the equation to calculate the optimal profile includes the push-off angle, we obtain different optimal profiles for vertical jumping (90°) and swimming sprint start (30°). Although MyJump only considers 90° vertical jump optimal profile (update in progress) the equation to compute optimal profile for any angle has been published here. So my objective here is to reduce this 35% deficit in force and shift my actual FV profile closer to the optimal for a 30° push-off.
The training program we used on our scientific experiment in such a case was pretty simple: heavy loads, maximal strength work, for 9 weeks with 2 sessions a week. In my opinion, any other training dose (sessions per week, total duration) would result in positive outcomes provided maximal lower limb strength is stimulated. More research is needed here to better design training programs (duration, content, etc…) but what we know for now is that even small training inputs resulted in substantial changes in the FV profile (decrease in the FV imbalance) and in turn increased push-off velocity. This resulted in our study in higher jump height, but in the case of a block phase, the final outcome would be an improved take-off velocity. Just do it.

On this basis, how can improve MY push-off performance

So my personal testing shows a force deficit, I will have to program a strength training that includes a majority of very heavy strength exercises for my lower limbs, and stimulate my maximal force as much as possible. Of course, taking into account all the other training components and performance determinants in a balanced and harmonious manner. Training is not an all/nothing world.
Then, in order to check my personal adaptations to the training program, I can do the FV testing (about 20min) every two or four weeks to check whether my responses follow the training predictions. This approach is dynamic and follows my training-induced adaptation. I may also program the duration of this specific program: short-term high dose or long-term more progressive dose, or any other combination…

Counterarguments and reasons for not doing it

Although at first sight this analysis and the training prescription make sense to me (but i’m totally biased), it might not be the opinion of my coach and S&C staff…here are counterarguments I may have to face, and my responses.
1/ wait, “Doctor”: what do you know about swimming? Who are you coaching?
Response: *facepalm*
2/ sorry, we usually do not work on lower limbs maximal strength. Swimmers don’t like it. We think it destroys their swimming legs technique, plus they prefer upper body strength work.
Response: *double facepalm* + no evidence on the long-term interference between legs strength training and swimming “technique”. However, evidence clearly show that strength work in the long term induces improvements in running economy, through a more efficient running “technique”…well ok running is different from swimming.
3/ you already have a pretty good start, why trying to improve it? You’d better work on your weaknesses.
Response: the thing here is that my start is ok, but according to the FV profile diagnosis, the margin for improvement is large and this could become an even stronger asset. Training philosophy here: should we work on our strengths and/or weaknesses…
4/ wait, your study does not include elite swimmers, right? So what if the results you obtained in trained soccer or rugby players differed in elite swimmers?
Response: I agree, but what if they did not? I would love to see such studies.

Important notes

First, our personal, unpublished observations show that most young swimmers we tested, and some elite sprint swimmers actually show a force deficit such as mine, so this approach may very likely apply to their case. Second, a recent MSc work I followed also shows this kind of force deficit in trained swimmers.


Swimming, and especially the shortest Olympic distance, is (now) a sport in which technological improvements are very unlikely or very small (once the body is shaved and piercings removed…), so a major part of performance improvements will likely result from training content and periodization (plus of course anatomical/genetical and pharmacological factors…). This is the reason why we think a better start performance (and in turn a better overall performance in the 50-m events at least) could result from monitoring the FV profile and most importantly from putting the conclusions of this diagnosis into practice and adapt (even a little bit) the training load accordingly. A diagnosis without a corresponding treatment is a loss of time.
Alternative solution: let your fingers grow!

7 thoughts on “Optimal FV profile in sprint swimmers: more than just another marginal gain?

  1. Hi!

    Although swimming coaches seems hard to convince, runners are already applying your methods…


    By the way, it's a pleasure to read your article.



  2. lol thanks…step by step…jump by jump 🙂


  3. Lot's of interesting things to test with the Sprint here, including what happens when the swimmer hits the water and short thereafter. Also, swimmers are a bit different, they always have to consider muscle mass vs total volume – there is a tradeoff between strength/density and speed!


  4. Thanks for sharing.
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  5. thank for good post and sharing……


  6. Sierra Moores 12 Sep 2019 — 04:52

    Hi Dr. Morin,
    My name is Sierra Moores. I am a Masters student at the University of British Columbia currently working with the national and varsity swim teams. I was wondering if you would be willing to share the unpublished data you collected on young and elite swimmers? Also would you be willing to share the name of the MSc student who you mentioned above who was also studying FV profiles in swimmers?


    1. Thank you for your message, could you send an email to me at jean-benoit.morin@univ-cotedazur.fr so we can chat about this ?


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