The Science Behind the training
High Intensity Training
High intensity training has shown how in less time you can get much better results. If you train for 60 minutes it's impossible to work at the same intensity you can work at for only 30 minutes. The higher the intensity of your workout, the longer it takes for you body to come back down to a resting state. Training closer to your maximum effort will keep your metabolism up for a lot longer than training at a steady state.
The size principle
Henneman’s size principle states that slow fatiguing, low force muscle fibres (slow twitch) are activated before fast fatiguing, high force muscle fibres (fast twitch). The best way to get all your muscle fibres working at the same time is to train in a way that fatigues the slow twitch muscles quickly. This will make the load you are working with feel much heavier, which is what makes your fast twitch muscles kick in to help you maintain the exercise. The BTB exercise programs are all based on minimal rest periods so by the end of the workout you will have activated all your different muscle types. The size principle relates to muscle activation, not the size of your muscles. You will improve stamina, strength and power at the same time.
Time Under tension
All the BTB exercise programs involve a high time under tension, meaning your muscles are engaged without any pause for long periods at a time. This is so you get the most out of the 30 minute workout. Short rests help create a big metabolic impact and increase muscle activation. The key benefit of training with a high time under tension is improving muscle tone. The longer your muscles are under tension, the more toned you will get.
Fast twitch muscle fibres are the only known stimulant of human growth hormone (HGH). HGH is a key hormone in recovery and your metabolism. HGH declines rapidly after the age of 21 and the amount of HGH you secrete depends on how much lean body mass and belly fat you have. The more belly fat you have, the less HGH your body produces. Therefore, one major goal of any fitness program should be getting your body to pump up its HGH production. BTB exercise programs will increase lean muscle, reduce body fat and will help you activate more fast twitch muscle fibre, so HGH levels will be improved.