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Having a plan before you step in the batter’s box is crucial. Whether it be mental or physical preparation, we must always get ready when we’re “in-the-hole” or “on-deck”.

If you watch any Major-League baseball game, or even a competing travel baseball league game, you will see a lot of different warm ups.

Most on-deck routines may look something like this:

  • Putting a donut on the bat and producing crappy swings
  • Putting a donut on the bat and producing 3 or 4 swings, taking the donut off and swinging a few more times
  • Taking 3 or 4 swings with a normal game bat
  • No swinging at all
  • Using loading patterns to time up the pitcher

If I were to ask you, “why do you perform _____ as your on-deck routine?” I hope you can give me a solid answer. If you don’t take any swings because you want to be fresh for the at bat, then great! You should always have a “why” to your routine (like I stated in one of my previous articles here).

Lately, there has been a lot of attention devoted to “weighted implement” training to enhance bat velocity, as well as using these same devices for a pre-at bat routine. Let’s highlight and explain the merit of some of these devices.

The Donut

You see many big leaguers throwing a donut on their bat for several reasons: to loosen up their body, to practice whipping their arms through the zone, to take violent swings, or just to look really strong. But, what’s the science behind it?

Some research [1] has looked at using the donut and its effectiveness of bat path and bat velocity. What did these studies show?

Well, by putting the weighted donut towards the barrel of the bat, not only are you adding weight, but the added weight is further away from the knob of the bat where the force is being generated from.

This added weight increases the moment of inertia (tendency to resist angular acceleration) in the swing.

Swinging the weighted donut seems to decrease bat velocity in most cases, and may also alter bat path efficiency [1].

Underload/Overload Bats


Some players like to use bats that are much lighter than their normal game bat. Why? I think many players believe that if they swing this bat with a ton of force, then their hand speed will be increased

The godfather of weighted implement training, Dr. Coop DeRenne, has done a ton of research on the effectiveness of underload and overloaded bat training on swing velocity.

To sum up years of his research, bats that are +/- 10% of your actual game bat can be used to improve swing velocity while maintaining bat path efficiency [1,2].

Staying within this range allows for high-threshold motor units within the muscle to be activated at peak contraction [1, 2]. Anywhere outside of this range will lead to fatigue.

Isometric Contractions

Isometric contractions? What the heck are those?

An isometric contraction is like squeezing your bicep as hard as you can in one position. Imagine trying to curl a 100-pound dumbbell. Chances are, no matter how hard you contract, you will just not get the weight up.

But, how does this even relate to baseball?

Well, there is some interesting research from Japan by Takatoshi Higuchi [3].

What Higuchi and others (2013) found was that holding a maximal contraction against an external load at the contact point during the swing INCREASED bat velocity when performed before a normal game-speed swing.

Screen Shot 2017-07-27 at 4.41.31 PM
A: Contact point with Top hand; B: Contact point with Bottom hand (Higuchi et al. 2013)

Being able to increase force production at a specific time point in the swing may be critical for an acute enhancement in performance.

The theory is that these maximal contractions will induce a phenomenon known as postactivation potentiation: an acute enhancement in force production [3].

However, the only limitation to this research is that there is a general rest time needed to see peak performance (around 3 minutes). Obviously, this certainly won’t help if you’re in the on-deck circle for 30 seconds.

Key Takeaways

Players use weighted implements to prime the nervous system, hoping that when they swing their normal game bat, bat velocity slightly increases.

If you could slightly increase your bat velocity in the acute time, this is an advantage for one big reason: TIMING! If you’re able to increase the amount of time you have to swing, then you should certainly take that advantage.

However, most players are using these modalities for the wrong reasons!

Since swinging a baseball bat is highly skilled in nature, the more you fatigue the nervous system, the greater the chance you will create adverse effects on your swing.

A highly skilled movement requires VERY specific motor unit firing patterns within the muscles. If this pattern is disrupted, mechanics are compromised.

Based on the science, using a weighted bat that is within the 10% range will not alter swing mechanics and can slightly increase swing velocity. If you plan on using isometric contractions, I wouldn’t pair it with high-intensity swings right after. We also need more research…I’ll get back to you on that one.

Keep swinging,


Jarad Vollkommer, CSCS


Click the link for the YouTube account to access the video version of this article!


  1. DeRenne, C. (1991). The donut: Does it improve bat velocity? Journal of Strength and Conditioning Research 13(3), 43-45.
  2. DeRenne, C., Ho, K.W., Hetzler, R.K., and Chai, D.X. (1992). Effects of warm up with various weighted implements on baseball bat swing velocity. Journal of Applied Sport Science Research 6(4), 214-218.
  3. Higuchi, T., Nagami, T., Mizuguchi, N., and Anderson, T. (2013). The acute and chronic effects of isometric contraction conditioning on baseball bat velocity. Journal of Strength and Conditioning Research 27(1), 216-222.

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