Interval Training Revisited

I found this awesome post by Randy Simpson on the Karate Resource Forum . He's cleverer than me so I have posted it here. Randy trains with Traditional Karate Research Institute. Visit their blog it is like an encyclopaedia of karate and conditioning.
 


"The duration between activities will depend on what you hope to accomplish- conditioning the aerobic or anaerobic power systems. The anaerobic systems are dominantly recruited for the first 2ish minutes of activity, after that threshold the aerobic system begins to take over. It takes about 2 minutes to replenish 100% of the ATP supply carried in your muscle tissue, so if your goal is the best possible technique, power output and control, a 2 min. interval is what you want. If you are looking at overall endurance, continuous performance will condition aerobic energy production. Going from one interval activity to another with no breaks will activate the aerobic system, so you will not benefit as much in anaerobic conditioning. All three power systems are heavily intertwined, and a percentage of each one is active even when another is dominant- but if you want to target specific adaptations, pay attention to the time duration and time between intervals. 

We often have three in our weekly classes, which makes for a very nice interval system. Two partners work in drill while the third stands on a balance board and keeps time and recovers. At the 2 min mark, one partner steps out, the stand-out steps in, and after a 30 second or so break the drill starts again, and so on. The guy who ends up pulling two rotations in a row gets a chance to recover ATP levels to a little under half of resting. A fact that our current "fitness and diet" markets have obscured for people is that higher intensity activity requires you to have a sufficient supply of carbohydrate-derived fuel on board. Once this fuel supply is burnt out and you switch over to fat-burning as a fuel source, intensity will drop. So if the goal is a training session full of numerous high-intensity bouts of exercise or drills, the trainee must have an adequate supply of carbohydrate in order to maintain that level. Something like Gatorade after an hour of this sort of training is very useful in replenishing energy stores for interval training. 

Whatever technical content you're working on can fit into this scheme to increase productivity and skill development while avoiding over-training injuries. For example, doing 100 kicks per leg is incredibly counter-productive. After a couple dozen the nervous system begins to "tone down" the muscles that are supposed to be prime movers, altering joint motion and technique. So blasting through a shitload of things at once is more training, but is not necessarily better or more productive. Taking those 200 kicks and breaking them into chunks of 20 per leg followed by a rest standing on a balance board will allow you to keep performing those kicks at a high level of technical accuracy and adequate energy production. The balance board (or single leg balance, etc.) gives you time to recover ATP and lower your heart rate while also giving the muscles of the torso, hips and legs a chance to work with different stimulus, thereby avoiding the "toning down" effect (aka arthrokinematic inhibition) so that they are fresh for the next batch of kicks using proper technique and muscle recruitment. Intervals provide a great way to exploit these mechanisms to avoid injury/fatigue and increase in skill and recovery rate."