Research Review: Factors in Bat Velocity


RESEARCH REVIEW: Factors in Bat Velocity

Don’t get me wrong, I love writing about pitching performance a lot and trying to figure out what we can do as performance coaches to continually develop our craft and apply it to our athletes based on research-driven methods.

However, as a position player, applying these concepts to hitting is just as exciting. Chicks dig the long ball after all!

As of late, every hitter is trying to utilize everything they can to increase their exit velocity. This is an outstanding metric to measure, but to me it simply means nothing for most of the population I work with.

Here’s why.

My job as a performance coach is to increase your performance. Pretty simple, right?

You can continually take swing after swing after swing trying to mash a ball off the tee or from front toss, or you can continually crush weight after weight to accomplish the same goal.

However, here is where I bridge the gap between the two.


For example, I can get you strong as hell, but if you can’t use that strength in the cage, then you’re wasting your time as a player. Sorry not sorry, folks.

As you’re developing your athletic qualities in the weight room in the off season, let that be your main focus. You can still swing in the cage, but you should be working on your mechanics at a low-relative intensity.

As we approach the season, we are STILL developing your athletic qualities, but then your focus should be more towards applying this strength and power to your swing.

Swinging a baseball bat, just like throwing a ball, is controlled violence.

If you want to increase your applicable swing velocity and hit the ball further more consistently, here is the latest research.

Force = Mass x Acceleration and Power = Force x Velocity

 I’ve written about the force velocity curve time and time again. That’s how important it is to baseball performance. Hopefully, this isn’t your first time hearing it.

If it is, here is a simple diagram of the relation between force, velocity, mass, and acceleration

Screen Shot 2017-08-02 at 6.48.30 PMForce x Velocity

General strength training using the squat, hinge, push, pull, and multi-dimensional core exercises can be used to get you stronger.

Special resistance training involves the manipulation of multiple training variables like speed, tempo, rest periods, range of motion, plans of movement, etc.

To increase your performance, we must train as close to the Force-Velocity curve as possible. This includes hitting all ends of the spectrum.

Importance of Swing Velocity

Increasing your swing velocity means you get to increase your swing decision time.

Hitters are juggling with 3 different variables in the box: identifying pitch type, the velocity of the pitch, and the location of the pitch [1].

Hitters must process all this information within a quarter of a second. There’s not a lot of room for error here.

The more time a hitter possesses on deciding to swing or not, the less time it takes to swing the bat and hit the pitch.

However, even if you increase your decision time, don’t automatically assume that your swing time will decrease. This is a skill that has to be trained with special resistance training.

If you don’t possess the strength and power to whip the bat around quickly then good luck!

An 80-mph fastball takes 0.5 seconds to cross home plate. If your swing time is 0.35 seconds, this means you only have 0.15 seconds to process all 3 of those variables, and THEN decide to swing or not! [1].

So, it is very important to increase your reaction time and visual measures as you work on your skills with the bat. (For a visuomotor article I wrote click here).

If you can swing a heavier bat at the same velocity as your standard game bat, a few things can happen when you make contact in a game: the ball travels further in the air, the ball is hit much harder, or both!

What’s interesting though is that high school kids use metal bats for a reason: to make the ball travel further!

Research shows that aluminum bats make the ball travel an extra 30 feet on average due to an increased swing velocity and the bats ability to hold onto more energy [1].

Compared to wood bats, aluminum bats that are the same length as a wood bat of the same weight can be swung quicker due to the weight distribution of the bat itself [1].

Another variable to consider with swing velocity is moment of inertia. Simply put, inertia is the ability to overcome force. In a baseball bat, this is measured with the bats length and distribution of weight.

The higher the moment of inertia, the heavier the swing weight [1]. Since metal bats have lower moments of inertia, they can be swung at higher velocities compared to wood bats [1].

The On-Deck Circle Dilemma

 Baseball is still growing as a sport both on the field and in the research lab. We are starting to find out a lot more when it comes to preparing for a game.

Most of the time, you’ll see a player who is swinging a bat with a donut on it as hard as possible because the bat “feels” lighter. Is this truth or fallacy?

To date, 4 studies looked at a different way of warming up thanks to Dr. Coop DeRenne. Based on Dr. DeRenne’s research, players should be warming up with a bat that is over/under 12% of their standard game bat.

In these 4 studies, swing velocity was significantly increased without altering swing mechanics. On the other hand, a very heavy (donut) or very light (23-oz.) have negative effects on swing velocity with a normal game bat [1].

Based on the science, a much heavier bat has a greater moment of inertia, which means a decreased swing velocity and bat path.

However, some MLB players still warm up with a donut. But why, even after the findings from research? Simply put, they are not humans! This research is meant for the high school population, who, on average, do not express levels of strength and power like older players.

The “standard” game bat for a high school player is 32 inches, 29 ounces. Staying within this 12% rule, a player should warm up with a bat that is no heavier than 32 ounces.

Implement Training: Over-Weighted and Under-Weighted Swinging

I don’t want anyone to expect that magically swinging a bat that is 12% heavier or lighter than a normal bat will automatically increase your swing velocity. Adaptations in the human body do not happen overnight, or within a few swings for that matter.

I think the combination of lifting weights and using swing training (over- and under-weighted) for around 8-12 weeks is the way to do it.

Previous research investigated the optimal volume of swings to perform with over- and under-weighted implements.

Based on this research, it seems that a ratio of 2:1 of weighted implements and normal game bats produce the greatest increases in swing velocity (6-10%).

For example, 100 swings of over-weighted and under-weighted bats and 50 swings of the standard game bat have previously been investigated and showed increases in swing velocity.

Interestingly though, previous research from DeRenne had a dry swing group and a batting practice group using weighted implements. The batting practice group had a 10% increase in swing velocity, which is the highest to date in research [1].

I think it would be interesting if there was a way for the “in-the-hole” player to take swings off a tee with the over-weighted bat prior to stepping in the box.

Another idea would be to take a few hacks with a 6-lb. medicine ball. I believe that taking swings when on-deck is a waste of time because it can a) possibly create fatigue in the swing and b) there is not enough rest time between each swing for an adaptation to occur.

However, based on the research, the best protocol to use would have to be from DeRenne: batting practice and dry swings with over-weighted (31-34 oz.) and under-weighted (27-29 oz.) bats, and finishing the day with the standard game bat (30 oz.).

As mentioned previously, most of this research is meant for the elite level player. If you do not have the prerequisite strength needed to display high levels of rotational power or bat velocity, your best bet may be to be consistent with your training.

Special Resistance Training: Strength, Power, Velocity, and Lean Mass

Being that the hitting motion requires muscle recruitment from the entire body in a specific order, it is important to train the entire body as well.

Research has shown that groups who implemented specific medicine ball drills into their training saw a greater increase in swing velocity.

In addition, adding whole-body plyometric exercises paired with strength training can further increase your swing velocity. This seems to be a good option for the average high school player who can understand how the body moves/works.

Time and time again, research shows that training the entire body as a unit with multiple modalities of exercise can increase strength and power in baseball players.

Now let’s shift our focus to the small muscle groups that are involved in the swing: the wrist and forearm. What are their contributions to swing velocity?

Well, they really don’t do much. Grip strength and forearm size do not have a strong correlation with swing velocity.

This is because of the size principle: smaller muscle groups fire before larger muscle groups. The torque that is applied by the hands and wrist are the last checkpoint in the energy transfer throughout the kinetic chain [1].

To increase your swing velocity, consider these variables: lower body strength and power, rotational power, and lean body mass.

More specifically, improving rotational strength and velocity with medicine ball training increases swing velocity based on the principle of specificity.

Training with medicine balls allows for the athlete to sync up movements from the lower half of the body at high velocity at a high frequency without producing a lot of fatigue.

Practical Application

Based on the research so far, here are some key points [1]:

  1. Warming up with a bat that is within 12% of your normal game bat can acutely increase swing velocity without altering mechanics due to the stimulation of type II muscle fibers
  2. VERY light and VERY heavy swinging have a negative effect on swing velocity (stop using the donut when you swing)
  3. Isometric contractions before swinging can also increase the stimulation of type II muscle fibers
  4. For the untrained high school player, swinging a normal game bat 100 times a day, 3 times per week, for 6-8 weeks can increase swing velocity
  5. For the highly trained high school player, taking 100 swings with under-weighted and over-weighted implements followed by 50 normal bat swings 4 times per week for 12 weeks can increase swing velocity
  6. Forearm and grip strength have very weak correlations with swing velocity
  7. Including medicine ball drills into your training, in a progressive matter, throughout the off season can increase swing velocity
  8. Increasing lower body strength power, rotational power, and lean body mass can increase swing velocity

Keep swinging,

Jarad Vollkommer, CSCS

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