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Bat Speed

Power Development System

The Most effective Bat Speed Tool on the market!

Looking for drills to improve bat speed?  Drills can be an effective method for

improving hitting mechanics which can potentially improve a player's bat speed.  

But what happens if a player already has sound mechanics?  The drills will fail to

improve bat speed and it will be time spent practicing with nothing to show.  

With the power development system there are NO DRILLS.  Just grab the bat and

swing it.  The weight of the bat combined with a program that regulates training

volume will do the rest.  Players, regardless of level and mechanical efficiency, can

see results.  Not convinced?  Check out the what the research has to say below


The Overload/Underload Power development system is an innovative training

method that was developed around the concept of Overload Underload training in

order to make dramatic improvements in bat speed in the least amount of time

possible.  The program was developed to be effective for players looking to get a foot

up on the competition in Little League all the way to players at the professional

level looking to get that little edge needed to play with the planet's most talented


The concept of Overload Underload training is a simple concept that has been used

since the 1970’s by Olympic athletes to get dramatic performance increases in

relatively short amounts of time.  Unfortunately, the concept still remained a

mystery to the majority of the general public until recent years.  Overload

Underload training is a training concept that uses resistances slightly above and

below what one would encounter in his/her respective sport.  So, for baseball that

would mean swinging a baseball bat or throwing a baseball that is roughly 20%

over and 20% under the normal weight one would usually encounter.  This concept

was studied extensively by the Soviet Union and other Eastern Bloc countries back

in the 1970’s.  These countries took great pride in their athletic accomplishments

and poured millions of dollars in research into more efficient ways to build better

athletes.  After experimenting with their Olympic throwers (shot put, javelin,

hammer, and discuss), they discovered that by increasing or decreasing the

resistance of the projectiles that were thrown in practice, they could produce

significant gains in throwing distance (and velocity) with objects of regulation

weight.  This was a huge find since strength and power gains from traditional

weight training often doesn’t always transfer well to more complex sporting

motions such as throwing and hitting.

The Soviets also found out that when greater than 20% resistance was added or

subtracted from the training implements, it not only didn’t increase performance

but it actually decreased it.  By using too much or too little resistance you will be

putting in a lot of effort and time to make yourself better, but it is actually time and

effort wasted.  This again goes back to the fact that timing and bio-mechanics are

essential to sports which require a high technical component.  When objects 20%

heavier or lighter than the original objects are used, then the bio-mechanics of the

movement is changed.  That means in order to accommodate for the additional or

reduced load, the athletes would change their movement pattern--which means, in

baseball terms, they would change the way they swing or throw, making the

training essentially useless.  The phrase "practice makes perfect" is often used by

coaches, but in reality only perfect practice makes perfect.  That means someone

wishing to increase his bat speed must take each practice swing with perfect

technique at game speed in order to have the hope of making noticeable

improvements.  To become fast and explosive, you must train to be fast and

explosive.  Quality always wins over quantity.  A quick example would be looking at

a marathon runner vs. a sprinter.  A marathon runner runs for miles at a time in

training.  A sprinter runs a few short sprints.  They are both running but the

differences lie in a) intensity, b) volume of training, and c) rest intervals.  Changing

those 3 variables makes the outcome of the training drastically different.  The take-

home message is:  if you want to throw faster, you need to practice throwing FAST.  

If you want to increase your bat speed, you have to practice swinging as fast as

possible with perfect mechanics.  Once we had an idea of where to start in regards

to percentages with the overload-underload, we began experimenting with players

of different ages and ability levels.  The goal was to find the ideal percentage to

weigh the bat in order to get optimal performance increases (improved bat speed).    

Today, many of the world’s top athletes use Overload Underload training to gain the

edge on their competition.  Elite sprinters and swimmers have been effectively

using a form of Overload Underload training to blow away world records.  The

sprinters and swimmers attach themselves to cords that either provide resistance

from behind or a slight tow from in front of them to create a pace that is slightly

slower or slightly faster than their personal best.  This has provided excellent

results and was recently used by soccer phenom Freddy Adu who trains at IMG

Academies, a training academy that has a history of improving the performance of

the world’s best athletes.

Many throwers from track and field continue to use the Overload Underload concept

with great results.   Even baseball, which has a history of lagging behind the times in

improving sports performance through science, is beginning to catch on.  Many

pitchers have been using Overload Underload training to drastically improve their

throwing velocity as well as strengthen their arms for the wear and tear of a

professional season.

For a more detailed article with more real world examples check HERE


Over the years there have been numerous studies done to determine the effects of

Overload Underload training on performance and safety.  The majority of Overload

Underload training research has been done with throwing a baseball.  The research

has all come back with stellar results.  Not only did the players participating in the

program make significant gains in velocity, but they also stayed healthy for the

following season, a difficult accomplishment considering the stress that throwing a

baseball puts on the muscles, tendons, and ligaments of the arm.  The most notable

study on the use of Overload Underload training for bat speed improvement comes

from Coop DeRenne, one of the world's premier research leaders in terms of

Overload Underload training for baseball.  DeRenne and colleagues came to the

same conclusion as many of the world's top sports scientists which is:  Overload

Underload training is simply one of the simplest and most effective ways to make

significant performance improvements in a short amount of time.  Here is a list of

pertinent literature pertaining to Overload Underload training and its effectiveness

on increasing performance.  Note - the vast majority of these studies deal with

training for improved bat speed or throwing velocity through the use of overload,

underload, or a combination of overload and underload techniques.  This is by no

means an exhaustive list; there are many more studies out there relating to

Overload Underload training.

Coop DeRenne, Barton P. Buxton, Ronald K. Hetzler and Kwok W. Ho. 1995: Effects

of Weighted Bat Implement Training on Bat Swing Velocity. The Journal of

Strength and Conditioning Research: Vol. 9, No. 4, pp. 247–250.

DeRenne, Coop EdD; Szymanski, David J PhD, CSCS*D

Effects of Baseball Weighted Implement Training: A Brief Review.  Strength and

Conditioning Journal:  April 2009 - Volume 31 - Issue 2 - pp 30-37

Bagonzi JA. The Effects of Graded Weighted Baseballs, Free Weight Training, and

Simulative Isometric Exercise on Velocity of a Thrown Baseball [master's thesis].

Indiana University, Bloomington, IN, 1978.

Brose DE and Hanson DL. Effects of overload training on velocity and accuracy of

throwing. Res Q 38: 528-533, 1967.

DeRenne C. Increasing bat velocity. Athletic J 62: 28-31, 1982.

DeRenne C. The donut: Does it improve bat velocity? Strength Cond J 13: 43-45,


DeRenne C and Branco D. Overload or underload in your on-deck preparation?

Scholast Coach 55: 32: 69, 1986.

DeRenne C, Buxton BP, Hetzler RK, and Ho KW. Effects of under- and overweighted

implement training on pitching velocity. J Strength Cond Res 8: 247-250, 1994.

DeRenne C, Buxton BP, Hetzler RK, and Ho KW. Effects of weighted bat implement

training on bat swing velocity. J Strength Cond Res 9: 247-250, 1995.

DeRenne C, Ho KW, and Blitzblau A. Effects of weighted implement training on

throwing velocity. J Appl Sports Sci Res 4: 16-19, 1990.

DeRenne C, Ho KW, Hetzler RK, and Chai DX. Effects of warm-up with various

weighted implements on baseball bat swing velocity. J Appl Sports Sci Res 6: 214-

218, 1992.

DeRenne C and Okasaki E. Increasing bat velocity (Part 2). Athletic J 63: 54-55,


Egstrom GH, Logan GA, and Wallis EL. Acquisition of throwing skill involving

projectiles of varying weight. Res Q 31: 420-425, 1960.

Elias J. The Effect of Overload Training on Speed in Baseball Pitching [master's

thesis]. Springfield College, Springfield, MA, 1964.

Fleisig GS, Phillips R, Shatley A, Loftice J, Dun S, Drake S, Farris JW, and Andrews

JR. Kinematics and kinetics of youth baseball pitching with standard and

lightweight balls. Sports Eng 9: 155-163, 2006.

Jarver J. Varied resistance in power development. Mod Athlete Coach 10: 5-8, 1973.

Sergo C and Boatwright D. Training methods using various weighted bats and the

effects on bat velocity. J Strength Cond Res 7: 115-117, 1993.

Southard D and Groomer L. Warm-up with baseball bats of varying moments of

inertia: Effect on bat velocity and swing pattern. Res Q Exerc Sport 74: 270-276,


Szymanski DJ, DeRenne C, and Spaniol FJ. Contributing factors for increased bat

swing velocity: A brief review. J Strength Cond Res February 27, 2009 [epub Ahead

of Print].

Van Huss WD, Albrecht L, Nelson R, and Hagerman R. Effect of overload warm-up

on the velocity and accuracy of throwing. Res Q 33: 472-475, 1962.

Vasiliev LA. Use of different weight to develop specialized speed-strength. Sov

Sports Rev 18: 49-52, 1983.

If you are interested in finding out more about the scientific studies on overload

underload training, a simple search at will reveal a large

number of studies.  To obtain the full study (not just the abstract) you might have to

go to a local library.  It’s important to point out again that numerous teams as well

as players from a wide variety of sports have already used Overload Underload

training and made drastic improvements.  The purpose of these studies is to show

that science is in agreement with what players in the “real world” have known for

years:  Overload Underload training works.  I point this out because oftentimes

people will make extraordinary claims about products or ideas being the next

miracle cure.  However, these products/ideas often have no science behind them

and within a year or two people who purchased these “scam” products will find out

they don’t work and learn that they have lost out on a significant amount of money.   

Bottom line:  Overload-Underload Training works.  Whether you are looking to

improve bat speed or throwing speed it's tough to make a case against all the

overwhelming evidence!