Force-Velocity Curve

The force-velocity curve is a term you might hear thrown around in sports science literature or coaching conversations, but it’s not always clearly understood.  In this article we’re going to cover:

What is the force-velocity curve?

The force velocity curve, pictured below, is simply a way to visualise the inverse relationship between force and velocity.

This relationship states that if someone generates maximal force in an exercise, then they will generate very little velocity, and similarly if someone generates maximal velocity in an exercise, then they will generate very little force.

In essence, think of a maximal back squat (very forceful) versus a maximal sprint (very high velocity).

The force velocity curve just visualises this relationship.

Quick Definitions

Force: In physics, force (measured in newtons) is an influence that can change the motion of an object.  Forces can be described as either pushing or pulling, and since forces have both a magnitude and a direction, it is a vector quantity.

Velocity: In physics, velocity is the rate of change of an object’s position, relative to a specific frame of reference.  Or rather, it is speed in a specified direction.  Like force, since it has both magnitude and direction, it is a vector quantity.

Where exercises fit onto the force-velocity curve

If we have maximal squats and deadlifts on one end of the force velocity curve, and vertical jumps at the other, there’s still a lot of room in between those two ends of the spectrum.

Generally speaking, exercises performed with lighter weights are going to favour velocity, whilst exercises performed with heavier weights are going to favour force.

Here’s a graphic adapted from Suchomel (2017) breaking down Olympic weightlifting exercise variations into a specific order on the force velocity curve.

As you can see, heavier exercises like isometric mid-thigh pull’s sit to the far left, whilst lighter jump shrugs (performed here with about 30% 1RM) sit on the far right.  Moderately heavy clean and snatch pulls sit centre left, and the relatively lighter power cleans and power snatches sit centre right.

With that said, it’s not always accurate to use load as a proxy for force or velocity.  We’ll talk more about the potential limitations of force velocity profiles and their relationships later.  

Where sport skills sit on the force-velocity curve

Where sports skills sit on the force velocity curve very much depends on which sport and which specific skill we’re talking about.  For example…

• If we’re talking about a rugby union scrum, that is an incredibly high force activity.

• Whereas if we’re talking about a drive in golf, that is an incredibly high velocity activity.

So there’s going to be a huge variation skill to skill.

The gold standard way to determine where sports skills sit on the force velocity spectrum would be to perform them in a lab with force plates, high speed cameras and other clever technology used by biomechanics specialists.  However, this isn’t an option for most coaches.

Your next best bet would be to look for the information online, as some common sporting movements have already been studied and published in research literature.

Lastly, you may just have to default to using a bit of common sense and observing the movement based on speed and load.  It won’t be a perfect estimate, but it will get you in the right ballpark.

Factors affecting force velocity profiles

Fundamentally, an athlete’s force velocity profile is a combination of their genetics and their training. 

Genetically, some people are simply going to be more built for force production, whilst others will be more built for velocity.  With all the will in the world, 4x World’s Strongest man Brian Shaw was never going to be a world class runner, and Olympic endurance gold medalist Mo Farah was never going to be pulling lorries.

We’re talking differences in bone structure, density, muscle attachments, fibre types, rate coding, lung capacity, height, limb length and about 100 other things.

But what about things we can change?  

1. Type of training.   Have you been training more for velocity or force?

2. How long we’ve been training for.  If you’ve been training for longer you’ll very likely rate higher for both qualities than someone who has just started training.

3. Training objective based on periodization and competition calendar.  If you’re in a general preparation phase or off-season, your training may be less specific to your competition demands, and your force-velocity profile may temporarily reflect this.

How to use the force-velocity curve as a Practitioner / Athlete

The force-velocity curve can be a useful tool for coaches and athletes as it can give you a clearer idea of which performance qualities you need to maximise, and where you should spend your training time.

• If you’re a golfer, for instance, it doesn’t make sense to spend all of your time performing maximal squats, bench presses and deadlifts.

• Conversely, if you’re a competitive strongman, it doesn’t make sense to spend all your time doing jumps and sprints.

Relatedly, since many sports performance outcomes relate to Rate of Force Development (RFD), force-velocity profiles of individual athletes can give coaches a reasonable indication of how that athlete can best increase their RFD, i.e. do they need to prioritise work on velocity or force?

For example, if an athlete’s force velocity profile shows that they are well strength trained and produce a lot of force, but have relatively low RFD, then that athlete can perform exercises further to the velocity side of the curve in order to see the quickest possible increase in RFD.

How to Create Force-Velocity Profiles

Fundamentally, a force velocity profile requires you to measure an athlete’s force production capabilities at different velocities so that you can plot them on a graph as above.  The exact methods vary per exercise (jumps versus sprints versus bench press for example) but the overall approach is very similar.  

For example, if you had to create a force velocity profile for jumping you’d have your athlete perform jumps at evenly distributed loads starting from 0% body mass and going up to the last load at which they can still jump around 10cm with.  So you might go with 15, 30, 45 and 60% bodyweight.  You can then combine this with basic data like body mass (kg), standing height (m), jump height (m), and a couple of simple lower-limb length measurements, i.e. at their fully extended position (m); and with knees bent at 90° (m). 

Or, if you were creating a profile for bench press you would attach a velocity tracking device like GymAware and measure bar speed at evenly distributed loads as a percentage of 1 rep max.  So you might measure at 15, 30, 45, 60, 75 and 90% of 1 rep max, taking 2-3 readings at each load to get an average.  You would then plot the velocities against the forces, with the forces being the bar weight multiplied by gravity (9.81) so a 60kg bench press would require 588.6N to overcome.

Theory Versus Practice

Real talk for a moment.  Having worked within strength and conditioning for the best part of 7 years, I think it’s important to interject some reality into the conversation.  Most of the training decisions and exercise selections I make will be based on many other factors outside of force-velocity profiles.  I mean things like…

• Athlete training history and ability
• Injuries, niggles and workarounds
• Available time
• Available equipment

So yes, theoretically we might say that according to athlete X’s force velocity profile and the demands of their sport, they should do exercise Y.

However, what if they’re new to the gym and it’s going to take me days or weeks to get them performing it correctly? 

Or what if they have an injury and that exercise poses a risk?  I sure as hell ain’t going to risk injuring a star player just because a graph told me they needed to do a certain exercise.

Then there’s time availability.  Often I’ll only get to see an athlete for an hour per week, and after a warm up that’s around 52 minutes of training time.  Is specific exercise Y going to give them the best bang for their buck in terms of that limited time? And is it going to help their long term development?

Relatedly, if a golfer already spends 18 hours per week playing golf and practicing high velocity movements, then do I really want to spend my limited time with them doing more of the same simply for the sake of force-velocity specificity?

All of which is to say that force-velocity curves and profiles have far less utility in practice than sport science researchers might suggest.

Training zones on the force-velocity curve

Maximum strength

These are your slower, maximally forceful movements, typically lifts performed at above 80% of 1RM.

Exercise examples: Heavy back squats, bench presses and deadlifts at 80+% of 1RM, isometric mid thigh pulls and isometric squats

Strength speed

The strength-speed training zone is all about the athlete producing optimal force in a shorter timeframe than the maximal strength zone.  This means that less total force is produced, but it’s produced a bit faster.  On the whole though, these are still reasonably forceful movements, and typically still use relatively heavy weights at 75-85% of 1RM.

Exercise examples: Squats, bench presses and deadlifts at 75-85% of 1RM performed with slightly greater speed.  Other examples include weightlifting movements such as the snatch and clean.

Peak power

Power is force x velocity, and this is the training zone at which exercises combine the relative amounts of these two qualities to produce the greatest peak (max) power outputs. Depending on the exercise this can be anything from 30-80% of 1RM.

Exercise examples: Power cleans and snatches at 60-70% of their respective maxes.  Moderately loaded jump squats and bench press throws.

Speed strength

This training zone sits sort of in between peak power and peak velocity.  Exercises are typically loaded at around 30-60% of 1RM, and move with a reasonable amount of velocity, with relatively lower forces than previous training zones.

Exercise examples: lightly loaded jumps and bench throws, medicine ball throws and weightlifting movements.

Maximum velocity

This zone is all about the need for speed.  Velocities produced are the highest, whilst forces produced are the lowest.  Exercises tend to use loads less than 30% of 1RM, or be unloaded.

Exercise examples: sprinting, assisted sprinting, bounding and plyometrics.

Further considerations around Force-Velocity profiles

Force-Velocity is not always perfectly correlated to load

Sprinting, for example, uses no external load, and produces very high velocities, but also produces reasonably high forces.  In fact, elite sprinters with fantastic RFD’s manage to produce substantial force outputs in very limited ground contact times.

Eccentric contractions alter force velocity curves

Fun fact, whilst in concentric contractions a muscle shortens as it contracts, in eccentric contractions a muscle is lengthening as it contracts.  This throws a lot of the force velocity curve we’ve discussed above out the window, as eccentric exercises actually produce more force as velocity increases.  

From a practical application standpoint, this means that a controlled eccentric combined with a fast concentric likely yields the best combination of force and velocity focused training within the same exercise.

The Force Velocity Curve is a Muscle Contraction Model, NOT a training model

It’s important to remember that whilst the force velocity curve may have some utility in training, it is fundamentally designed as a model for muscle contraction, and not as a model to guide training.  It should simply be one tool in a much wider toolbox.

What I mean by this is that scientific models are often designed for laboratory purposes, in which functions can be isolated (often to the cellular level) within very controlled environments. In real world training this is not the case.  Movement is dynamic and complex.

To provide an analogy, a weapons engineer might use a technical model to design a firearm, and say that it works in a specific way, which is factually accurate.  However, knowledge of how that firearm works in an engineering lab is very different from knowledge of how that firearm works under pressure in live combat, especially after it has been heated and cooled a thousand times, been covered in sand and been reloaded hundreds of times by humans rather than robots.

Conclusion

The force velocity curve is a useful model that can be applied to the training of athletes to generate force velocity profiles and indicate potential areas of training priority.  It is a useful concept to understand but isn’t a perfect tool, and application can often be faced with challenges in real world sports performance and strength & conditioning settings.

Next Steps

1. If you found the article useful, feel free to share it, and consider checking out our related articles.

2. If you have any questions or comments, ask them down below.

Further Reading

• Suchomel et al. (2017) – Enhancing the force velocity profile of athletes using weightlifting derivatives. 

• Valle. C (2021) – Why force velocity training concepts can fail to deliver.

Reference

If you quote information from this page in your work, then the reference for this page is:

Parry, A (2021). Force velocity curve. Available from: https://sportscienceinsider.com/force-velocity-curve/. [Accessed dd/mm/yyyy].