My weight is 63kgs and height is 5'7" (170 cm). I practice wing chun at home (I rarely have an opponent to practice against). Sometimes, I feel my punching power could be better. To increase my punch power, do I need to add weights to my workout program? And how can I make my knuckles stronger? What exercises are helpful for me in these cases that I can do at home?
Power in your punches comes from; muscle to generate force, correct shifting of weight/movement, and coordination and technique to get the most of that (alignment of structure, correct angle of attack, timing, etc.).
If you want more muscle to generate force, you need to do some kind of resistance training - that can be weights, it could be resistance pushing against a partner or some other thing that has mass like a heavy bag, using resistance bands, or it could be training in water, which has resistance. Weights and resistance bands are convenient, and you can increase the amount of resistance to increase how much power your muscles adapt to.
Strengthening the knuckles involves increasing the bone density, which takes years of training. Bones increase strength along the line of force - which, you can get by doing knuckle push ups or simply staying in push up position on your knuckles.
However, that takes a long time, and can only go so far - your most immediate concern is correct alignment of your wrist and striking soft tissue of your target, not the skull.
The other two parts of getting more power - timing, technique, are things you'll want to find someone more skilled than you to help you on.
There are two schools of thought based on two distinct principles as to how to generate a punch with maximum effectiveness.
In schools similar to karate the force comes from pushing after you connect with the target. Someone punching in this manner will train to strengthen their muscles in order to apply more force. These punches have reletively short range but apply force for a longer time. https://youtu.be/S9wODMKiHAA?t=4m41s
In schools similar to muai thai the focus is different. Rather than push through the target a whip like action is used to accelerate the fist so that it achieves a higher speed. These punches have longer range than those in the karate style because the shoulders also move. However this style of punch applies force to the target for less time. https://youtu.be/akQr4oS6GZo?t=46s
From what I have seen of Wing Chun the shoulders are fairly static so I think you should be looking more at the first method.
Whatever method you use every punch has an optimum distance at which it connects. Too far close and you have a push (Bruce Lee's famous one inch punch is very much a push) Too far away and you won't have enough distance left to actually transfer any energy.
I think the most relevant equations to explain this are
Work=Force x Distance and Transfer of Momentum = Force x Time
In other words you want to maximize the force with which you strike, the Distance over which that force is applied and the amount of time your strike is in contact with the target.
For this you need raw muscle strength. So any dynamic strength training for the arm muscles should be suitable.
Regarding punch power
Some basic physics together with some thoughts on punches and kicks may help:
- [impulse] = [mass] × [velocity]
It is much better to improve speed by technique (!) and exercises (which may include weight training, but as I take it in another sense than you think of it) than weight, if you want to hit harder: Becoming heavier will slower your movement due to higher inertia and therefore have opportunity costs.
In addition, if you only go for weight in your exercises this may reduce your speed because of reducing white muscle fibres (responsible for speed) in favor of red ones (responsible for strength) if you do not train well-balanced. Body weight is gained best through training of maximum strength, i.e. heavy weights, small numbers. What you need is speed strength, which can be achieved through weight training with certain exercises and smaller weights with more repetitions, but there are several things to be considered, e.g. weights not being too heavy for you and thus stressing your joints. All this is subject of discussions in training science, though.
- [pressure] = [force] / [area]
You should hit with a small area (two knuckles, ball/heel of the foot), because it will improve the effect proportionally in the area hit, e.g. bones like ribs.
Regarding strengthening of your knuckles
There already is a question with some good answers here.
Martial arts do not work if you do them on your own. Get yourself an instructor that can show you how to build up strength and speed from your heels, through your legs, hips and upper body to your shoulders and onwards if you want to improve punches. There is no point in training something over and over again that may turn out to be biomechanical nonsense. He will also have exercises fitting your specific needings if he is good.
As a general comment: Intra- and inter-muscle coordination (learnt through countless repeats of techniques and exercises) as well as the technique itself is much more important than the muscle-weight. The coordination is where muscles get their power from. Bruce Lee had nearly 5'8'' and at his best not more than 70 kilos ;)
It is physically correct with greater weight and muscle power you will definitely be having a greater impact while punching. The greater weight will have a greater momentum as soon as the muscles give you the speed the impact will be doubled.
momentum = mass X velocity
Muscle Power is more important than weight, as heavier bodies are much more difficult to accelerate. If your hands are heavy and you don't have the power behind, you will lose the stamina quickly. So, concentrate more on the muscle power by doing correct workouts like:
- Non Static Stretching
- Standing Stable in Good posture
- Concentrate on your weaker muscles
- Do Contrast Training
- Use Sprints And Drills
- Do Polymetrics
- Lift Heavy
- Rest Longer
After you get the muscle strength Force to make the larger impact.
As far as the kicks are concerned, concentrate more on the techniques and speed. Practice both on punch bag to perfect.
I see a lot of good answers, so I will just add some wing chun specific remarks. First of all. Wing chun punch gets its power from technique and body structure. Punch is guided by your elbow and comes from your center line. Its focus is in transfer of energy into the target. Punch alone is a whip like movement, as you don't want to push you target away. Another important aspect is the concept of softness or relaxation of your punch. When punching to the air you wrist and fingers should wiggle. Like a jelly. Basicaly, more relaxed the punch, the more powerful it will be.
Now, how you can train to improve your punching. As you might often hear in wing chun. The answer is in your first form. Siu Nim Tau. It guides you to proper technique and with repetition it goes to you muscle memory, so you can strike more relaxed. Another good tool is wall pad/bag so that you can train punches with actualy punching something.
To punch and kick hard you have to have proper technique. Punching power doesn't come from your arms but from your whole body. Most of the power you generate comes from your glutes. When you punch you're driving power from the ground.
Most fighters who lack the necessary power to move their opponents backwards are typically called arm-punchers. What this means and how it correlates to the two large muscles groups defined above [glutes and lats] is that these types of fighters are not engaging these massive muscles to gain leverage and power. They are throwing from their shoulders and not pushing from the ground, rotating at the hips, putting their back into it and turning their punches over at the end. Delivery of a power punch should enlist the resources and be dependent on these large muscle groups. Granted, there are many more variables and more intricate tricks to delivering a knockout blow, but without laying this basic fundamental groundwork, the resulting punch will lack the force it needs to get the job done.1
Muay thai and boxing both teach proper punching technique to generate the most power. Karate punches while fast, do not possess the same power.
The same idea applies to kicks. Basic Muay thai/Sanda kicks both derive a lot of power from hip rotation. The most powerful kick is a Taekwondo spinning back kick, which again generates it's power from rotation. Spinning Back Kick Example
So yes weight and muscle do impact striking power, but it's only with proper technique that you efficiently transfer that power from your muscles into your strikes.
Also knuckle strength isn't as important as wrist strength. The stronger your forearms are, the less likely you will break your hands. But again proper technique (the angle and alignment of your arm) is the most important thing to avoid injuring yourself.
I disagree with @Bankuei advice on resistance training. Unless your a brown/black belt your focus should seriously be on your technique.