Increase Bat Speed

Overload and Underload Training

Strength and Conditioning Series

Baseball and Fastpitch Softball


This  Increase Bat Speed with Overload and Underload Training is excerpted from our new book, The Ultimate Hitting Training Guide (click for book details).

The strength and conditioning articles found in this Building Rome Series are specifically designed to increase bat and ball exit speed (power) for the baseball and fastpitch softball hitter.

Note that the products discussed on our site have been used in our training of hitters with great success. At no extra cost to you, things you buy through our links may earn us a commission.


Introduction to Overload and Underload Training to Increase Bat Speed

Bat speed programming for the hitter is a tricky subject because of the unique nature of the swing. It isn’t easy to simulate this movement in the training environment. The swing is a very intricate pattern that involves multiple segments of the body to interact (kinetic links).

Increase Bat Speed

Overload/underload training maximizes bat velocity by adjusting brain patterns and strengthening the fast-twitch muscles used in the hitting stroke. Numerous studies have reached a similar conclusion – the use of weighted bats improves bat speed.


Why it Works to Increase Bat Speed

The hitter’s brain can stop making changes because the body has developed a road map to execute the movement. This roadmap then becomes a permanent fixture in the player’s mind, efficient or not; it is there unless a new challenge is presented to the system. The new challenge becomes a different weighted bat. This forces the brain to stop using “autopilot” and create better roadmaps to accommodate the change.


Overload Training to Increase Bat Speed

increase bat speed

Swinging with an overload bat can have multiple benefits. First and foremost, overload bats are beneficial in developing strength in the most crucial areas. The core, shoulders, and forearms strengthen by utilizing a weighted bat sequence program involving overload—the hitter swings with increased resistance.

Also, using overload bats can help develop a more efficient movement pattern using the human body’s self-organization ability. When the body feels the heavier bat and the hitter intends to hit the ball with power, the body responds by moving in the most efficient manner possible. Practicing with heavier bats teaches the nervous system how to generate more force.

Optimal hitting positions are positions of great leverage and body control. Issues with energy transfer up through the body can be ironed out by training with overload bats. If you can take something uncomfortable like swinging a 20 percent heavier bat and make it comfortable, then your feeling of control and confidence will be high when you pick up a regular bat.

Click the link to shop for an affordable and easy way to adjust bat weight using weighted bat jackets.


Underload Training to Increase Bat Speed

Training a hitter’s movement with an underloaded bat allows the action to occur at a higher velocity, thus recruiting more fast-twitch fibers. The Central Nervous System is responsible for these adaptations that are crucial to the explosive athlete. Simply put, moving faster helps train the athlete to move faster.


Measure Bat Speed and Ball Exit Speed

As overload/underload training progresses, electronically measure and track bat speed and exit velocity (click on Measure and Track Bat Speed and Measure and Track Ball Exit Speed for how to measure these analytics).

“The first effective feedback system is measurement. The things we measure are the things we improve. This holds true for the number of pages we read, the number of pushups we do, the number of sales calls we make, and any other task that is important to us. It is only through measurement that we have any proof of whether we are getting better or worse.” (Clear, 2007)


Overload and Underload Program to Increase Bat Speed

To become fast and explosive, you must train to be fast and explosive. After completing dedicated and consistent overload/underload training, all players gain velocity. Most players gain 4–8 mph; however, that depends on age and skill level.

It is easy to create an underload/overload program with old bats in the garage, a donut, or heavily discounted used bats.

The proven formula for improved bat speed:

Use bats that are 20-30 percent lighter or heavier than during game competition.

​Step 1.  Swing a heavy end-weighted bat 3 sets of 10, for a total of 30 swings.

Step 2.  Swing a heavy balanced bat 3 sets of 10, for a total of 30 swings.

Step 3.  Swing a light bat 3 sets of 10, for a total of 30 swings.

Step 4.  Swing game bat 3 sets of 10, for a total of 30 swings.

Rest 1-2 minutes between each set.

The hitter should take 120 swings a day three times a week for four weeks.

Utilize dry swings, a tee, or soft toss.

Swing your hardest/fastest on every swing.

For extra motivation, incorporate the use of a bat speed radar, setting a lower limit speed for a successful swing, depending on the bat’s weight.

“I’m not going to lie, each session I completed was a workout. After the first two days my hands had blisters even while wearing batting gloves. The third session of my first week I wrapped tape around my palm so I could complete the training.  Each session I exerted 100% on every swing.  It was worth it, I felt so quick and powerful heading into my senior year of college and attribute much of my power numbers and increased confidence in this program.” (Thoreson, 2018) 


Other Strength and Conditioning Articles You May Find Helpful

Click on the links below for further free articles to increase speed and strength. Each exercise is specifically designed for the baseball and fastpitch softball hitter.

Rotational Core Strength to Increase Bat Speed

Fast Twitch Sports Performance for Baseball and Softball

Strength Training for Kids


Building Rome Series Books: Building the High-Level Swing Series

step by step hitting fundamentalsClick Building the High-Level-Swing Series to learn more about our new two-book hitter series containing a detailed and comprehensive description of 100 hitting fundamentals and 140 step-by-step drills that efficiently construct the batting swing from the ground up.

In the Building Rome Series of books, the construction of skills are in functional order, providing a “roadmap” to becoming a great hitter.

All baseball and fastpitch softball players can “climb the Roman Coliseum steps” to become a powerful and productive hitter.

Enjoy the quest!