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What is Eccentric Overload Training and Why Does it Matter to Golfers?

Which of These Do You Think is Better?

One of the most effective tools or methods to get stronger (and faster) is one that you’ve likely never heard of.  Eccentric Overload Training, specifically using a flywheel mechanism (pictured, right), is an incredibly unique and effective way to improve your overall strength and force output. 

What Does This Mean to the Golfer?

Contrary to popular opinion, golf is a power sport! An effective golf swing is one that is able to apply a near maximum force to the handle of the club while keeping a relatively neutral club path AND have the clubface pointing at the intended target (hopefully), all in the span of about 1 to 1.5 seconds. No small feat, indeed!

There are 3 parts or phases to any movement pattern. The CONCENTRIC (muscle shortening), the ISOMETRIC (no change in muscle length) and the ECCENTRIC (muscle lengthening). For simple purposes, let’s look at a simple squat motion. The downward squat motion = ECCENTRIC, the midway point at the bottom = ISOMETRIC and the upward/standing movement = CONCENTRIC

The eccentric part of the motion is often “underloaded” due to the fact that most of us, when lifting traditional free weights, are lifting a weight that is limited to an amount we can overcome in the concentric phase. However we are much STRONGER in the eccentric phase of a movement. Think of lifting a heavy object off the floor. It’s much easier to set it down than it is to actually lift it up, right? This is a big opportunity to improve overall strength by overloading the eccentric part of the movement with the use of a flywheel! Enter the kPulley!

How Does the kPulley Work?

Flywheel training gained notoriety when NASA (US National Aeronautics and Space Administration) used it in the 1990s to prevent muscle atrophy in astronauts during space flights. Due to the fact that there is zero gravity in space, there was a need for NASA to be able to load the muscles of the astronauts under tension while they were in space for months at a time.

The resistance of the flywheel is due to the flywheel moment of inertia as a result of its rotation and not due to gravity. The flywheel mechanism stores the concentric energy applied to it (think of the standing motion a the squat). Then, during the eccentric muscle action, (sitting motion of a squat) the energy initially applied in the concentric part of the movement is applied to the eccentric motion, creating an “overload” on the eccentric part of the motion in order to absorb and neutralize the pre-produced kinetic energy. In this phase, the participant uses eccentric muscle action as a brake to decelerate the downward movement. Again, for the golfer, this means an improved ability to apply (and absorb force) in a short amount of time, which is very similar to the golf swing.

The kPulley & kPulley Go by Exxentric are eccentric flywheel training devices that we have been using for some time, and we have found that they are extremely effective (more than rotational medicine ball throws) at improving club head speed. You can CLICK HERE to read our research on this!


Josh Leyes

Golf Performance Coach

Disclaimer: This blog content is for general educational information purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. References available upon request.

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Chris Finn

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