Our bodies must be efficient at providing energy for each zone. Interval training develops aerobic capacity as well as anaerobic conditioning without the deleterious effects on muscle that extensive aerobic training can have. Training exclusively and extensively in the aerobic zone leads to muscle loss and corresponding losses in speed and power.

Next time you watch a track and field event, notice the physical differences between the short-distance runners and the long-distance runners.

How do you supply your muscles with the energy to fight, train, or perform everyday or sport-specific activities? Your body generates energy from three sources — phosphagen, glycogen, and oxygen — based on the effort and duration of the task. You consume glycogen and phosphagen, and your body absorbs oxygen through the lungs and skin from your surrounding environment.

Phosphagen is used in the very initial stages of exercise, the first ten seconds, and powers highly intense effort. To train this energy system:

• Train intensely for 10–30 seconds.

• Rest and recover for three times as long as you worked.

• Repeat 5–10 times.

EXAMPLE: Do a twenty-second sprint, rest for sixty seconds, and repeat five times. Then immediately do twenty seconds of pushups (as many as you can in that period), rest for sixty seconds, repeat five times, and then repeat the sprints for a total of three intervals.

Glycogen is used for moderately intense exercise that lasts for two to three minutes. To train your glycogen pathways you should:

• Work up to 6–8 intervals.

• Rest for twice as long as you worked.

EXAMPLE: Do one minute of hard shadowboxing or punching and kicking on a heavy bag, then rest for two minutes. Repeat six to eight times.

Oxygen is used for relatively easy exercise that lasts longer than several minutes. To train your oxygen energy source:

• Train at an easy to moderate intensity of 10–60 minute sets for an equivalent period (three minutes) of time.

• Repeat 5 times.

Phosphagen and glycogen are gained and utilized through anaerobic exercise, while oxygen is gained and utilized through aerobic exercise. You must train in the use of all of these energy sources in order to be truly fit. In the context of a fight, you might make it through the first round with good anaerobic conditioning, but unless you score a first round knockout, you will need equally good aerobic conditioning to make it through the rest of the fight.

Krav Maga training uses continuous full-power combinations of combatives and techniques to build anaerobic capacity. These can be isolated drills or used within longer sessions of shadowboxing.