Energy is needed to produce physical movement, maintain body temperature, and keep up with all
the metabolic activities in the body. In our bodies all physical movements relies on the
compound adenosine triphosphate, or ATP. ATP is stored in the muscles, so, it is immediately
available to produce movement, however, storage of ATP in the muscles is limited, so, any movement
that lasts longer than a few seconds requires more ATP to be produced. Our bodies have three
systems that can produce ATP. The ATP PCR system, the glycolytic system, or lactic acid system, and
the oxidative system. The first two systems are anaerobic systems, meaning oxygen is not required
to produce ATP, the oxidative system is aerobic, because oxygen is needed for ATP production. The
ATP PCR system is based on movements lasting about 5 to 15 seconds, such as strength power movements,
like a golf swing, jump, throwing, or racquet serves. These types of quick burst movements can be done with
ATP that is stored in the muscles, during short sustained power movements or any quick bursts,
such as a short sprint, ATP will provide the energy alone for the first few seconds, with a compound
called creatine phosphate, or PCR, buffering the ATP for another few seconds. Like ATP, the amount
of PCR is limited, so this system can provide energy for movements up to about 15 seconds.
This energy system produces ATP very quickly, but not over a long duration. Next, energy demands shift
to the glycolytic system. This system relies on a rapid breakdown of carbohydrates, glucose, which is one
of the most basic forms of carbohydrates is constantly circulating in the bloodstream.
And glycogen is a stored form of glucose, in the muscles and liver. This blood glucose, or glycogen,
is broken down to create ATP through a process called glycolysis. During this energy supply
process, a substance called lactate is formed, and hydrogen ions are released. It's believed
that the accumulation of these hydrogen ions in the muscle, causes the muscle to become more
acidic. Contributing to fatigue and a burning sensation. Exercises that are performed at maximum rate for
between one to two minutes, such as the 200-yard dash, depend heavily on the lactic acid system for
ATP energy. This energy system produces ATP very quickly but again not over a long duration. The
oxidative system involves the use of oxygen. Through two complex metabolic processes, the krebs cycle,
or citric acid cycle, and the electron transport chain, ATP is produced. This energy system with
all of its processes can't produce ATP nearly as quickly as the first two systems, however,
this system can produce ATP for a much longer duration. This system can use carbs, fats, or if
necessary, even protein. However, fats and proteins have to be broken down, so, when the system uses
them, the process becomes longer. This system is used for longer duration activity such as a bike
ride or long run. The chart on the screen shows an estimate of the percentage of energy used from
each system, along with time plotted at the top. As you can see the ATP PCR system dominates at
the beginning, then glycolysis becomes a dominant energy provider and then energy really relies on
the oxidative system. Here are two other charts, the one on the left shows an estimated rate of
ATP production per second, for each system. It also shows the rate for carbs and fats for the oxidative
system. You can see how much more rapidly the ATP PCR and glycolysis systems are at ATP production.
On the left is the chart showing the aerobic ATP production for trained and untrained people,
showing the benefits of well-trained persons, as they don't run out of energy easily. Each of these
systems can be trained to be more productive By changing your workout routines, doing explosive
moves, like box jumps, you can improve system one, by doing circuit routines, going from
one exercise to the next, with little to no rest in between, and using lighter weights, you can train
system two. And by doing a 20 to 30 minute cardio session of low to moderate intensity, like walking,
jogging, or biking, you improve system 3. It's a good practice to train all three systems by
altering your workout routines. The body is amazing and it adapts very quickly. Changing up routines
also provides mental stimulation, which helps overall health and can help people stay motivated
to work out regularly. Remember this folks, hit your body as differently as possible as often possible.