Hi! Its good to do 3x5 with 6 kg dumbbell(I want to increase that weight to 30 kg or more after some time) straight punches?
Dumbbells Punches
There are a number of issue with using Dumbbells to increase you're "Punching Power".
1) As Pavel stated, "....Your punching mechanic would just get worse and worse."
a) Your techniques changes as the load increases.
b) Research shows with light loads, power is developed in the first part of the movement. In the final part of the movement you decelerate; learn to decrease your power.
"The National Strength and Conditioning Association's Basic Guidelines for the Resistance Training of Athletes states that
"performing speed repetitions as fast as possible with light weights (e.g., 30-45% of 1RM)
in exercises in which the bar is held on to and
must be decelerated at the end of the joint's range of motion (e.g., bench press)
to protect the joint does not produce power or speed training but rather teaches the body how to decelerate, or slow down. Source:
Plyometric bench training for 1rm increases
c) As per Glen, "...Direction of force doesn't match the direction of movement... Dumbbell bench press will more closely match..."
As Glen states, the Bench Press is more replicative of Punching than Standing Punches.
However, the Traditional Bench Press, as noted above, teaches you to decrease your Power at the end of the range of the movement.
Bench Press Training Solution
There are two methods that can be used to ensure Power is maintained and developed in the Bench Press through the full range of the movement.
1) Bench Press Throws: This mean going "Ballistic"; a body or objected must become airborne. In plain English, that means in the Bench Press you need to throw the bar up into the air.
Bench Press Throw Training Load should be 10 to 40% of your 1 Repetition Max. That means if your Bench Press Max is 300 lbs, the "Throw Load" should be 30 to 120 lbs.
The safest method is...
Smith Bench Press Throws (Video Demonstration Below)
Bench Press Throws ensure that you continue to accelerate, develop Power, from the start of the movement to the end.
2) Accommodating Resistance Bench Pressing: This means attaching Band or Chains to your Bench Press. This allows you to continue to push as hard as you can to the very end of the movement; Power is maintain and increase at the end of the range of the movement rather than decreased with the Traditional Bench Press.
Accommodating Resistance Bench Press Training does not allow the bar to go airborne; be thrown into the air.
Developing Standing Punching Power
Standing Punching with light dumbbells works to some extent but isn't optimal, for the reason stated above
.
The optimal method is to perform Standing Punches with Bands. Band allow you to develop Power through the full ranged of the movement without impeding your technique.
Final Thought
The foundation of Power and Speed is built on Limit Strength (you 1 Repetition Max). The stronger you are the more force (Strength and Power) you are able to produce.
Kenny Croxdale