Weight Training – Helpful or Harmful for Karate?


A question I receive often is, “Is weight training helpful or harmful for my karate?”

That’s a great question and often a confusing and misunderstood topic. In this article I’ll explain the pros and cons of weight training, how it affects your technique and finish up by setting you straight on what kind of training routine might suit your karate goals.

Before we get to that let’s explore why we’re training in the first place. According to a survey I held back in 2002 of over 800 karate students, the number one reason for karate training was (as you might expect) self defense (37.2 %) followed closely by fitness (25%). The remainder of the results were spread over self confidence, strength building, competition and discipline. Since our results showed that over 62 % of people train for the top 2 reasons we’ll base our arguments on these two points — that we actively participate in karate to increase our self defense ability and our fitness.

So how do our karate goals relate to weight training exactly? Consider for a moment, if you will, how weight training might affect your self defense ability. Will carrying more bulk inhibit your speed and make you slower? Or will the extra mass help with the power of your strikes and give you extra strength while grappling?


Fitness on the other hand – what exactly do people mean when they say they want to be fitter? Again most people don’t understand fitness, just that they want to be “fitter” than what they are now. Are we talking about having more vitality or a stronger body, anaerobic or aerobic fitness? What’s the difference? Can weight training affect these goals also?

Finally what kind of weight training are we talking about here? Do people generally mean going to the gym to bulk up or are they more interested in building muscles for endurance? Each of these methods affects how your muscles develop, which brings us back to… what do you want from karate?


If your reason is for self defense and you’re practicing a striking art like karate, then it makes sense that you want to be “built for speed”. We want to end a conflict within seconds, not let the fight continue for 15 rounds. As far as generating power, always remember a slow technique is a useless technique.


“Have you ever heard of the slowest gun fighter in the west?”
– Tommy Morris


So why is speed important?

Firstly without it you’ll never hit your target or block/evade in time. The second reason why speed is so critical is more scientific. As karateka we should be interested in how to develop as much force as possible with our technique, of which speed is a critical factor. Newton’s second law of physics reveals the following:


Force = Mass x Acceleration


Now getting a little more technical we see that it’s not actually speed but acceleration that is critical. It’s how quickly you can develop speed from a resting position to its maximum velocity at impact. With that we now see that:


Acceleration = Change in Speed / Change in Time


Yikes… if your eyes just glazed over at the thought of high school physics, don’t worry. I’ll make this as painless as possible. Promise. =) Basically it boils down to this: the faster your technique is traveling at the point of impact, the more force it will generate. How do we get faster acceleration? Through faster contraction of our muscles of course!

As you may already know different kinds of muscle fibers are responsible for different muscle functions. Everybody has both slow twitch fibers and fast twitch fibers, about 50% of each kind, which are intermingled in different proportions in different muscles. The slow fibers utilize repeated slow contractions for strength and endurance, like maintaining your posture or marathon running. These fibers don’t fatigue nearly as quickly as fast twitch fibers, which contract up to 10 times more quickly, and also fatigue much faster. Ever had the “lactic acid buildup” after doing something like 15 fast jabs with your front hand, or holding your arms above your head for an extended time? That’s a byproduct of muscle fatigue and the fatiguing of your fast twitch fibers in that muscle.

Some experts say that the percentage of fast to slow twitch fibers is entirely controlled by genetics meaning that if you’re born slow, there’s nothing you can do about it. Other experts in the field of athletics say that although the ratio is genetic you can teach slow twitch fibers to be fast and vice versa depending on your training routine.

A marathon runner would be interested in developing more slow twitch fibers to help with endurance. Some people have been tested to have as much as 80% slow twitch fibers which is great for endurance, while a karateka should be interested in developing their fast twitch for more powerful strikes.

So what’s all this got to do with weight training?


You see the method by which you train your muscles will either develop more slow twitch or more fast twitch fibers. Regular weight training and plyometrics build slow twitch fibers, through repetition. That’s what gives you your endurance. If you’ve ever lifted weights you know that the general concept is to do, for example, 3 sets of 10 reps for each muscle group. This repetition is what builds your strength. Over time you’re able to lift more weight and increase the number of reps or sets.

If you want to develop strength then there’s nothing wrong with weight training. In fact weight training and plyometric exercises are perfect for developing strength and endurance. This might be a great option for you if you are simply looking to increase your strength and fitness, something that grapplers would be interested in doing.

If you want to develop speed on the other hand, regular weight training won’t help in the long run. Sure initially as you build more muscle, you’ll have a few more fast and slow twitch fibers created, but what we’re really interested in for speed is focusing on developing our fast twitch fibers.

That involves a whole other method of training. Most people think that simply using weights and making faster curls develops speed… well, again this develops strength not speed as it doesn’t target the fibers we want — even if you do it as fast as you can. Actually it makes fast fibers act like slow fibers! Anything that involves repetition builds slow twitch fibers.

There’s a very specific method of speed training to develop only fast twitch fibers. The entire process is outside of the scope of this article today, but the basic concept is to teach our muscles to be fast by teaching them to be elastic. Teaching a muscle memory if you will, so your muscles can “snap” into position, just the way a stretched elastic band accelerates from rest to its maximum speed in an instant when you stretch and release it before it returns to its unstretched state. Through this type of training, the muscle “learns” its length and twitches to produce the fastest acceleration to that particular length every time.

The basic method involves using a stretch band and an isometric contraction for a measured amount of time. Unlike weight training where the aim is to make loads of repetitions, this type of speed training doesn’t use that method either… as repetitions build strength and not speed.

So what’s the solution to develop both speed and strength? Basically your training program needs to contain both strength exercises and CORRECT speed exercises to develop both slow and fast fibers individually.

So if we go back to the original question “Is weight training helpful or harmful to karate?” we see it depends on whether you want to build strength or speed. If you want strength and endurance, sure it helps – and will help your aerobic fitness also. If you want speed, then the answer is no. Weights, plyometrics and endurance training don’t help develop fast twitch fibers (anaerobic technique), which you need more of to develop more speed.

For someone studying BJJ, Judo or other grappling/wrestling where strength and endurance is helpful, weights are great. For someone involved in primarily a striking art, weights alone without speed training and proper stretching can be harmful to speed.

In future articles we’ll take a closer look at the strength vs speed dilemma and give you some ideas of how to develop both.

Until next time…

Stay safe, train hard.



Textbook of Medical Physiology, 8th edition, Guyton. 1990. ISBN-10: 0721630871


Karate Drills To Increase Your Speed, Stamina and Fitness

Want to increase your speed, power and endurance? Or are you looking for drills to work your class like never before? In my “125 Dynamite Drills” you’ll find a truck load of drills to develop your strength, endurance, fitness and speed.

You’ll discover:

  • 20 Warm Up & Endurance Training Drills to build strong muscle, aerobic fitness and to tone the body…

  • 16 Basic Technique Exercises to develop powerful strikes, improved focus and muscle memory…

  • 10 Killer Kata Exercises to challenge anyone at any level. These drills are not style specific and great for working both mind and body, so anyone can see immediate improvement in their execution and understanding of kata…

  • 20 Fighting Drills and Exercises to increase your reaction speed, timing and confidence.

  • 9 reality based self defense drills to bring you as close to the real thing as possible so you’ll be better prepared.

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5 thoughts on “Weight Training – Helpful or Harmful for Karate?

  1. Hello Jason:

    Great article about speed versus building mass, I had the same question for many years from my students, and you explained the concept in a very clear way.

    Thanks for your articles

    Sensei Taylor
    Taylor's Martial Arts

  2. Great article Jason!! Very insightful, informative & interesting. I agree TOTALLY about the 'need for speed'. You can't be as fast as you possibly can, if you're too bulky and/or muscular. I try to stay as lean as possible, exactly for that reason. Thanks once again Sensei Jason. Take care & God Bless!

  3. In the book, "Bruce Lee – The Art of Expressing the Human Body", which covers the many evolutions and routines that Bruce Lee went through for his development, Bruce describes comprehensive martial arts training as being comprised of three disciplines – Strength/Weight Training, Cardio and Stretching. All three were needed in order to lead the martial artist to their fullest potential.

    While he got plenty of cardio through his martial arts training (in addition to his near daily runs, cycles, etc), and also stretched on a daily basis, he wasn't introduced to weight training until around 1965. He very quickly understood the benefits of weight training, primarily the principle that a stronger muscle is a faster one. However, once he began to bulk up, he realized the issue that having "bigger" muscles can bring, mainly in slowing one down. So, after gaining nearly 20 pounds, Bruce reversed direction and began focusing more on developing strength, but without the excess bulk that bodybuilders seek. Ultimately, he found a balance and was a strong proponent of weight lifting, developing numbers routines for his students. I'll actually begin an experiment in which I follow the only detailed record of his progress in the next week or so.

    Reading your post has reminded me of some of the negatives in terms of possible speed loss however. Now, I need to find an accurate way to measure a variety of strikes so that I can compare the before and after (the records record only a 44 day period, so thats what i'll be following). It would be very interesting to see if I develop an increase or decline in speed. Thanks for the post.


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