The faster the ball comes off your bat, the more likely you are to get on base. It is that simple. Quality contact is necessary for maximizing your exit velocity. That is why barrel control is important. However, the weight of the bat and how fast you swing it is fundamental (kinetic energy = 1/2 mass x velocity2). How fast you swing is a combination of efficient mechanics and strength. Let’s assume you already have good mechanics. We are going to focus on strength and speed.
Perhaps the most obvious way to get stronger is lifting weights. I have no training in this area, so I am not going to pretend I know much about it. You should find a trainer who understands weight lifting and strengthening the muscle groups important for swinging a bat. Also, keep in mind that a weight lifting routine for hitting may not necessarily be good for pitching (and vice versa).
Another way to get stronger and swing faster is to do an overload/underload bat training program. Overload training increases functional strength, while underload training recruits fast twitch muscles to increase swing speed. There is no consensus about the one right way to do bat speed training, although most programs use 20% overload and underload bats. The important thing is to swing the training bats regularly if you want to see results (just like with weight lifting, cardio, etc.).
I looked at seven bat speed training programs (see the bottom of this page). All have somewhat different training routines and recommendations. Using these programs as a guide, I have created a basic and inexpensive overweight/underweight training program that you can do at home or a facility.
Overload/Underload Training Program
What you need:
- 20% overload bat, end loaded*
- 20% overload bat, handle loaded (optional)*
- 20% underload bat*
- Your game bat
- Batting tee with a soft, flexible top
- Whiffle balls, sponge, or foam baseballs
- A space big enough to swing your bat
- A net or wall to hit the ball into
- 15-20 minutes (how much time the program takes)
*You do not necessarily have to buy expensive new bats. See the “Training Bats” section for information on how to make or find your own inexpensive overload and underload bats.
Below are two overload/underload training programs. Adjust them as you see fit. (You may want to take a look at the summary of training programs at the bottom of this page to get some ideas.) Program 1 uses end loaded, under loaded, and game bats. Program 2 adds a handle loaded bat to the rotation. I am not completely convinced that there is significant benefit to swinging the handle loaded bat, but a lot of programs recommend it.
IMPORTANT! READ THIS BEFORE STARTING YOUR TRAINING PROGRAM
Warm up. Begin all your training sessions by stretching and getting warmed up. Besides your stretches, you should do five repetitions each of our four hitting drills at about 60% to 75% effort with your game bat. These warm up drills will not only get you loose, but reinforce good mechanics.
Tees and light weight balls. I strongly recommend using a batting tee (with a soft rubber top) and light weight balls with limited flight.
Swing as fast as possible with good mechanics. When you start doing the program, you should swing the bat as fast as possible without your mechanics breaking down. Do not change parts of your swing in an effort to go faster. Move the bat as fast as you can using your normal mechanics.
Hit Line Drives. Quality contact is not as important as speed. However, when you swing your target should be line drives.
Do Not Swing If You are Tired. Take a break if you get tired, particularly before you use the underload bat. The aim is to swing as fast as possible. Your swing will be slower if you are tired and you will not be activating your muscles to their potential.
— PROGRAM 1 — (Overload/Underload/Game Bats) – Do 5 sets of 5 swings with the end overload and underload bats. Do 4 sets of 5 swings with your game bat. Rotate bats after each set. Change the rotation pattern each day. (Total number of swings are listed below.)
| End Overload | Underload | Game Bat | Swings per Day | Days per Week |
| 25 | 25 | 20 | 70 | 4 |
— PROGRAM 2 — (End Overload/Handle Overload/Underload/Game Bats) – Do 3 sets of 5 swings with the handle overload and game bat. Do 4 sets of 5 swings with the end overload and underload bats. Rotate bats after each set. Always separate the two overload bats with a game or underload bat when you rotate. For example, the rotation could be (1) End Overload, (2) Underload, (3) Handle Overload, and (4) Game.(Total number of swings are listed below.)
| End Overload | Handle Overload | Underload | Game Bat | Swings per Day | Days per Week |
| 20 | 15 | 20 | 15 | 70 | 4 |
Training Bats
Most programs use 20% overload and 20% underload bats. There is no scientific proof that these weight percentages are best, but this seems to be the consensus of professionals. Here are the weights you should use for a 20% weight change. I would round up for overload bats and round down for underload bats. (Bat weight is in ounces.)
| Your bat weight | 20% of Weight | 20% Overload | 20% Underload |
| 26 | 5.2 | 31.2 | 20.8 |
| 27 | 5.4 | 32.4 | 21.6 |
| 28 | 5.6 | 33.6 | 22.4 |
| 29 | 5.8 | 34.8 | 23.2 |
| 30 | 6 | 36 | 24 |
| 31 | 6.2 | 37.2 | 24.8 |
| 32 | 6.4 | 38.4 | 25.6 |
You can, of course, buy your overload and underload bats. (Note that a Camwood bat can serve as a handle loaded bat, but not an end loaded bat.) However, there are much cheaper alternatives.
Underload Bat – An old -5, -8, or -10 bat can be your underload bat. You may have one at home. Cheap used bats can be found on eBay or Sideline Swap. Put a new grip on the bat if one is needed.
Overload Bat – You may be able to find a used bat with the weight you need on eBay or Sideline Swap. You can also create an overload bat by adding weight to an old -3. Needless to say, you should not use your game bat for this. If you make an overload bat, you can attach lead tape or wrap washers, pennies, etc. around the bat with duct tape. For an end loaded bat, put the weight on the barrel above the sweet spot. For a handle loaded bat, put the weight below the half way point on the bat. You may be able to use a batting donut or weighted cuff, but it must fit below the bat’s mid-point.
Here are a couple videos about making overweight bats:
How to Efficiently Create Heavy and Light Bats (Overload, Underload)
$5 DIY Heavy Bat End Loaded 100 Penny Bat
Tee, Front Toss, or Pitching Machine? Light Weight Balls or Baseballs?
I see no reason to do overload/underload training on anything other than a tee and using light weight, limited flight balls. The goal is to swing as fast as you can without having your mechanics breakdown. This will help you develop strength with the overweight bat and speed with the underweight bat. Swinging at a moving ball will not make a difference. Hitting off a tee allows you to focus on your task, which is swinging fast. Hitting a real baseball makes no difference as well. Light weight balls are better because they make hand fatigue less likely and can be used to train in more places.
Summary of Different Overload/Underload Training Programs
Total swings are listed.
| Program | End | Handle | Under | Game | Swings/Day | Days/Week |
| Driveline Free | 10 | 10 | 20 | 10 | 60 | X |
| Driveline Simplified | 8 | 8 | 8 | 8 | 36 | 3 to 4 |
| Driveline Experiment | 10 | 10 | 10 | 10 | 40 | 4 |
| Hitting Vault | 20 | 20 | 20 | 10 | 70 | 3 to 4 |
| Bat Digest | 20 | X | 20 | 20 | 60 | 4 |
| Diamond Dreams | 20 | X | 20 | 20 | 60 | 3 |
| Better Baseball | 30 | 30 | 30 | 30 | 120 | 3 |
Driveline Free – Free 6 Week Hitting Program. The program includes 5 or 6 days of hitting per week, but only two days focus on overload/underload training.
Driveline Simplified – Simplified Bat Speed Program.
Driveline Experiment – Driveline weighted bat experiment.
Hitting Vault – Bat Speed Training Program Example. This program used several different weights of overload and underload bats. So, I combined them into into end load, handle load, underload, and game bat categories.
Bat Digest – Underload Overload Swing Plan.
Diamond Dreams – Diamond Dreams Baseball Academy Overweight/Underweight Bat Program. This program gradually ramps up the number of swings over the course of six weeks. I listed the swings for week five.
Better Baseball – Better Baseball Coaching Increase Bat Speed in Just 6 Hours of Training. Note that 120 swings per session seems excessive, especially compared to the other programs.
OTHER OVERLOAD/UNDERLOAD PROGRAMS
Hitting: Weighted Bats with Joe Kelch – Northern Illinois Univ. – Five bats (78, 66, 48, 24, and 16 ounces). Three sets of 10 swings with each bat using tees or flips. Three times a week for six weeks.
Improve Your Hitting 