Punchbag training is excellent to work on developing power in your karate strikes and it’s great fun 
A powerful kick that was made famous by Bruce Lee, he used to call side thrust kick, ‘the stop kick’.
In the film, Enter The Dragon, there is an excellent example of Bruce Lee combining the thrust kick with his ‘Bruce Lee Burst’, he could cover 8 feet in three quarters of a second! The famous kick is delivered during the fight with O’hara (Bob Wall), if you get a chance, check it out.
Executing Yoko Geri Kekomi (Side Thrust Kick) On The Punchbag.
Here’s just one, of the several variations out there. This one is very basic, in the more advanced way of kicking side thrust kick, you would not Rotate 90 degrees, counter clockwise, instead you would simply lift the knee as fast as possible to the front of the body then continue from number 3 below.
From Hanmi no kamae (Half forward facing combative posture), left leg in front.
1. Rotate 90 degrees, counter clockwise, on the left supporting leg and lift the right knee, high and to the left side of your body.
2. Thrust the leg forwards towards the punchbag.
3. Driving the hips and body weight into the target (image 1).
4. Yoko geri kekomi is a Kekomi is a thrust kick as opposed to a keage (snap) kick, so there is a slight delay at the completion of the kick, as you finish the thrusting action.
5. Recover the kicking leg strongly, then step forward or backwards, into Hanmi no kamae (Half forward facing combative posture).
6. Use the supporting leg strongly, when executing the kick and after impact, so you can recover your posture quickly.
