The word power is thrown around a lot in the strength and conditioning world, but unfortunately most coaches and athletes aren’t fully aware of what power truly is.
I am talking about the real definition of power as defined by biomechanics. Today I am going to explain this definition in as simple terms as possible, and then I will give you some ideas regarding application. The best part of today’s discussion is once you understand this biomechanical equation, application is only limited by your imagination.
Cliches
In sports, coaches and athletes are always talking about working hard. You will constantly hear phrases like:
- “out work”
- “do work”
- “hard work”
- “work hard”
Those are all nice phrases, but what do they mean? I am glad you asked because I am going to tell you.
You might be wondering why I am talking about work when I said that we are going to talk about power. If you stick with me, I will explain. You can’t have power without work because at the end of the day power is performing a large amount of work in a short amount of time. So let’s break it down!
Work
Work is defined as force x distance. Most of us already know that force is mass x acceleration. Now my goal is not to show you my skills in biomechanics. My goal is to help all of you understand the complexities of power in the simplest of terms. Therefore force in its simplest of terms is moving a mass. How do I know force is referring to displacement or moving positions? I know this because acceleration is a change in velocity, and the time it took to make that change. With work we’re referring to the distance that this force occurred.
When a strength and conditioning coach or biomechanist refers to power, they’re talking about doing work as quickly as possible. Power explained even more simply can be stated Power = Force x Velocity. We will come back to this shortly.
Power pretty much explains all things in sport that bring the crowd to their feet: hitting a homerun, sprinting at high speeds (foot striking the ground as the end point of the moment of inertia from the body’s center of gravity), a tackle in football, or a massive leap in the sky for a rim-shattering dunk.
Laws
Almost every athletic feat is going to revolve around one of Newton’s three laws of motion. Let’s take a look:
Newton’s First Law (Law of Inertia) – Newton’s First Law of inertia states that objects tend to resist changes in their state of motion. An object in motion will tend to stay in motion and an object at rest will tend to stay at rest unless acted upon by a force.
Newton’s Second Law of Motion (Law of Acceleration) – “The velocity of an object changes when it is subjected to an external force. The law defines a force to be equal to change in momentum (mass times velocity) per change in time.” Newton’s second law of motion explains how accelerations occur. (McGinnis, 2013). The acceleration (tendency of an object to change speed or direction) an object experiences is proportional to the size of the force and inversely proportional to the object’s mass (F = ma). Therefore, a greater force will cause a faster acceleration, and a heavier mass will create a slower acceleration.
Newton’s Third Law of Motion (Law of Reaction) – This one states for every action there is an equal and opposite reaction. Therefore when an athlete’s foot strikes the ground during a sprint causing ground reaction forces between the foot and the friction encountered on the ground, the athlete is propelled in the opposite direction of the foot. The foot strike is creating force downward and backwards, and the ground with the help of friction creates a force upwards and forwards allowing the athlete to sprint down the field or track at an acceleration proportional to the force applied to the ground.
The one common trait amongst the three laws is force. Therefore force needs to be a consideration in all solid strength and conditioning programs. However, force can’t be the only consideration as velocity plays a massive role in power. If you want to improve an athlete’s sprinting speed, there are multiple concerns with none as important as the velocity the foot is traveling at the instant it strikes the ground. Does that mean coaches should only train velocity aka speed work? It depends, but probably not.
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Speed
If you desire to increase the sprint speed of an athlete, there are multiple factors that need to be considered:
- Relative Strength – this has to be a major concern since that’s the main mass that an athlete works with during most athletic events that involve sprinting, jumping, and change of direction.
- Absolute Strength – this is especially true up until a solid base of strength is developed with most sources stating 1.7 to 2 times bodyweight in the king of all strength lifts, the back squat. However this isn’t equivocal as there are many conflicting pieces of research out there with varying standards all over the place. I will talk more about this one a bit later.
- Sprint Mechanics- I want to say right away that I love sprint specialist coaches. One of my favorite coaches in the world is Coach William Bradley. If you don’t know him, that’s your loss. He’s a magician with the 40-yard dash.
- Mobility/ROM – this is where I believe a lot of arguments center without people knowing. The body has to be able to move throughout complete ranges of motion without restriction. One easy example is the effortless elevation of the femur placing the foot at a peak height before being driven into the ground will provide for maximal potential energy which is equal to mass x gravity x height (hint I am talking about the height).
- Optimal Neural Adaptations – I am really talking about the neuromuscular system, and the relationship between the agonist and antagonist (when one is contracting, the other is relaxing). This comes with practice and the proper stimulus in training.
- Power Production – we’ve already talked about this one a bit, and I will touch on this one a bit more later in this article.
- Tendon Stiffness – Strain Energy is Another type of potential energy is also used in sport. Strain energy is energy due to the deformation of an object. This comes with proper strength training, plyometrics, bounding, and other drills on the track.
There are a few coaches out there taking relative strength to all new levels. Unilateral squats, pullups, pushups, and unilateral hinges are all a part of the equation. It isn’t just pullups. How stable is your leg when the foot strikes the ground? These are all considerations.
Absolute strength is where there are a lot of variables that come into play. When I talk about absolute strength in regards to squat strength, I am talking about a full range of motion. Yes, I agree that partial ranges of motion are great for power development. However only when joints are taken through a full range of motion is synovial fluid released in the joint providing nourishment and lubrication. Not to mention, if I train an athlete like a powerlifter, that means I am teaching them to bottom out at right below parallel. That would be me purposely shortening the ROM of a sports athlete just to get them stronger. This doesn’t make sense in the world of athletics.
Sprint Mechanics should probably have been discussed first on this list. If you want to get good at a certain activity, you need to do that activity. The same goes for sprinting. This leads me to my belief on “how strong is too strong.” When you get so strong that the volume required to get any stronger takes longer than you have set aside for strength training, then you can start to slow that process. If not, strength training will start to take away from other categories that need to maintain their state of equilibrium. It’s the athlete’s version of homeostasis. All categories related to faster sprinting times need to improve in relation to one another with the priority remaining sprint mechanics. I hope this makes sense.
I already discussed range of motion, but the deal is that strength can’t come at the cost of range of motion. When that starts, you are now a powerlifter. An athlete has to be able to travel through space within all the planes of motion. For that to happen the body needs to maintain a complete range of motion. Kinesthetic awareness and proprioception rely on the athlete’s ability to flow through space unrestricted. To be clear I am not referring to hypermobility, but rather I am referring to optimal mobility.
Optimal neural adaptations will take place within the neuromuscular system with proper sprinting mechanics as well as using movements in training that encourage this agonist/antagonist relationship. Weightlifting is the perfect example if you think about it. The body produces a massive force, experiences complete relaxation from antagonist allowing for maximal acceleration during the change of direction aspects of the pull under aka third pull phases and drive under phases of the jerk. Just like in sprinting the best weightlifters are not just the athletes that can produce the most force, but rather they are the athletes that have systems effectively inhibiting those antagonists during those crucial phases. Specificity relates to the style of training as much or more as the specificity of the movement.
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Power Production is something that we discussed earlier on, and was the lead in to the entire argument. Once an athlete realizes those amounts of absolute strength where volume requirements exceed that of more important aspects, velocity based training should become the primary component in the weight room. I recommend developing a complete force-velocity curve with the movements that you intend on using in the weight room. I recommend movements such as bilateral back squats, unilateral squats, deadlifts, trap bar deadlifts, push press, and rows. Once you define the quality of speed/velocity that you are deficient, that becomes the focus of one’s strength training. However at this point you can call it speed-strength training. This will be a lot less taxing on the body, and will yield big dividends with speed.
Tendon stiffness is where plenty of athletes still have room for improvement that could lead to sprint personal records. This form of potential energy is related to tendon stiffness and the amount of deformation of the tendon. Tendon stiffness can be improved with plyometric training and complete range of motion training at the ankle and knee especially. There’s a lot of great work out there right now. You can check out plenty of new work out there on tendon stiffness. Some of the guys creating all-time vertical leaps have tapped into this quality.
So there it is guys. This is my way of coaching athletic performance. I don’t believe that you can be dogmatic toward any one component. I believe the ones that are trying that are the ones that are inefficient in one or more categories. Check out @spikesonly on Twitter for some real information in the sprinting world. I promise you will thank me. Now can we all go back to creating holistic workouts that develop well-rounded awesome athletes?
McGinnis, Peter M.. Biomechanics of Sport and Exercise . Human Kinetics, Inc.. Kindle Edition.