The phrase 'interval training' should be synonymous with the word EXPLOSIVE. It can involve biking, climbing, squat thrusts, plyometrics, and many other things, but most famously sprinting.
It involves 3 things:
1. Many and large muscle groups,
2. maximum heart rate / cellular stress
3. periodic cool downs
Now flex your leg as hard as you can. Just do it!
Notice at first, it's easy and your leg feels strong, but as you're reading this and time passes, it becomes harder to maintain a powerful flex. This demonstrates the different sources of ATP (Adenosine Tri-Phosphate), and how they wear out, forcing the muscles power to diminish.
Interval training is like fine tuning your exercise to the natural flow of cellular energy. The cell's most basic form of energy is ATP. There are 4 basic sources of ATP which are too complicated and boring to get into very much, but each successful source of ATP is a less immediate and lower source of energy. During the most intense activity, a cell's initial store of ATP can be exhausted in two second. The second source of ATP (the ATP-PCr system) may only last 10 seconds and the third (the glycolytic system), which starts at same time as the ATP-PCr system, lasts as little as 2 minutes. These first three sources of ATP is called the anaerobic system. The fourth (the oxidative system) is the primary supplier of APT during lower-intensity activity, when the anaerobic system is not needed much. It is slow and can sustain only moderate activity, but may last quite some time. Interval training targets the anaerobic sources of APT which are the fastest and most ready sources of energy for use.
In many ways, Interval training is superior to long-lasting cardio exercises of less intensity. Less intestine cardio uses more of the oxidative system; which does not reserve lean muscle mass very well during exercise. There are many benefits of interval training. Along with burning maximum calories relative to time, interval training preserves and Promotes more muscle growth. It also increases the resting metabolism which is crucial for burning fat and benefits cardiovascular strength. Interval training may only last 10 to 15 minutes, but you may feel like you're about to die. Interval training is about power and intensity not necessarily endurance. Types of interval training, rather than moderate cardio, can be ideal for all age groups and fitness levels.
Interval training should start with a warm-up. During the warm-up you should be able to have a conversation; otherwise you're using the anaerobic system too much too soon and should slow down. A warm-up should last 5 minutes, is meant to get the blood pumping and the body ready for the actual workout.
After the warm-up is finished, it's time to sprint. This should be highly intensive; as if you're trying to escape death from a crocodile, an aggressive water hippo, or a rapid land-tuna; yielding some sort of above-water breathing apparatus. If this part of the set is not enough sufficient, the cell's ATP source will default to the oxidative system rather than the anaerobic system. You should try and target the anaerobic systems during the heightened portion of the interval, so minimizing the time from 30 seconds to 3 minutes and maximizing the intensity is critical.
The next part of this set is recovery. A slow recovery is needed for the anaerobic systems to renew and prepare itself for the next set. Recovery should last 3 to 5 minutes until a slow breathing rate is comfortable; then it's time to sprint again. Do 3 to 5 sets to complete the workout. Also, remember that this principle of interval training can be applied to many forms of exercise.
With or without starting any exercise program nutrition is always 100% necessary. Malnutrition can lead to a loss of muscle mass, a reduced metabolism, and can have countless other negative effects. During interval training, malnutrition will also cause low energy, dizziness, poor exercise, and poor results. A proper balance of complete proteins, complex carbohydrates, and healthy fats should be utilized for any lifestyle or exercise program.
There are dangers to interval training. It may be wise to take interval training slowly at first; building up to higher intensity over days, weeks, or months. This of course, depends on your cardiovascular fitness levels and age. Consult your doctor before starting an exercise program to avoid any possible risks.