In simple language Aerobics means with ‘air’. By ‘air’ it means Oxygen. It refers to continuous utilization of Oxygen by the body during certain physical activities. Such utilization is possible only when the condition of heart is pretty good. Importance of continuous utilization of Oxygen by the body (at a fast speed such as during aerobic activities) is that it helps oxidation of fatty acids (i.e. Fats) and thereby lowering the fat level in the body. Aerobics is therefore preferred for fat loss program. Aerobic activities are aerobic dance, stationary cycling, treadmill, rowing machine, stair climbing, running, jogging, brisk walking, swimming etc.
Utilization of Oxygen takes place via two modes. First – the transportation of Oxygen from the outer environment to the Blood in Cardiovascular system (Heart) of the body via Lungs. Second – transportation of Oxygen from the heart to the cells of the each body-part through blood. To perform these two functions at an enhanced level, the capabilities of lungs and heart are required to be improved. A conditioned heart can pump more blood per beat and that means heart works less to pump more blood per minute. This is called Cardio Vascular Fitness or VO2 Max i.e. intake of maximum volume of Oxygen per minute by the heart.
You can form your own aerobic sequences consisting of different steps, which when done non-stop in smooth motion, will give aerobic workout. So you can form a sequence consisting of various asanas or exercises or weight training exercises ( also called circuit training) to get some aerobic workout out of your own exercise routine.
Aerobic Dance & Music: When you do any exercise fast enough on the beats of a music in a rhythmic pattern it looks like a dance. This kind of dance exercise is called aerobic dance. In every music which is used for aerobic dance there are beats. Beats are sounds of those drums and other bass instruments which occur at regular intervals with a rhythmic pattern inside the music. Above these beats superimposed is melody of the music.
Inside the music how many beats occur per minute decides the speed of a music. In a fast music beats per minute is higher than the slow music. You have to move your body as per the speed of the music. Therefore when you perform aerobic in a fast music you are said to be working on high impact. The speed of the music sets the TEMPO of the class.

To count the number of beats per minute in a music you

• Play the music
• Listen for the beats
• When you identified the beats, start a stopwatch and start counting the beats.
• Count the beats for 10 seconds and multiply it by 6.
• This is No. of beats per minute of the said music (BPM).

The speed of the music or Tempo of the class may be slow, moderate or fast. Slow music is used for simple body movements and stretching. Moderate Tempo is used for Warm-ups and Low intensity movements. Fast Tempo is used for high intensity movements. It is important to note that while faster music may lead to more uncontrolled movements there-by causing the chances of injury, too slow music will also create a heavy feeling and the body in space will work with gravity which is injurious to joints.
The number of beats per minute in a music is further divided in small groups called Measures and Blocks. Four beats constitute 1 Measure and 4 Measures constitute 1 Block. After one Block you may change your body movement pattern.
For example: / ----- / = 1 Measure / ----- / + / ------- / + / ------ / + / ------- / = 4 Measures = 1 Block.
Movement of the body: Body moves with the beats. At the stroke or sound of the beat body weight is placed on the surface or the foot touches the floor. Body movement takes place between the sound of the beats. Body takes time to move in the space in between the beats and may consume some beats during the movement. Some movement requires only 1 beat to be executed. Other movements require 2 or 4 beats. It is therefore necessary to place your centre of gravity precisely on time with the beat to continue with the music. The change of dance steps also takes place between the beats or by consuming some beats. But the beat consumption should also be rhythmical i.e. you have to complete the step within a measure so that you can repeat the same movement in the next measure.
It is also necessary to note how many beats you consume to complete a step. For example while spot marching you strike your foot with every beat. However while doing knee-up you consume one extra beat to raise the knee. Therefore if in 1 block you perform 16 Marching you can do only 8 knee-ups in 1 block. Here you should not try to do 16 knee-ups in 1 block.
When you start an aerobic class you start with slower to moderate speed and slowly increase the speed of the class. This allows the cardiovascular system of the body i.e. heart to increase the heart rate per minute slowly. Any music selection for the aerobics class should be on the above lines. The Tempo of the class should be set in a progressive Manner. However if you start the class with slow tempo and all of a sudden jump to fast tempo or all of a sudden jump down from fast tempo to slow tempo, something as illustrated hereunder, then it will have serious negative impact on the body and therefore not advisable. But if you plan for a high impact class for the well trained members then you can start your class with a higher Tempo (say 132 BPM ) so that you can reach your high intensity peak safely and quickly and stay there for a longer time.
However during morning sessions and during winter months it is always advisable to start the class with moderate speed. The Music you are playing plays an important role in determining the mood of the class. It should be such which gives the motivation to move with energy and smile.