In terms of fitness, there are two primary sources that the majority of people think about. One is cardiorespiratory fitness and heart health and the other is muscle strength to move the body. Runners seem to put the cardio factor first since getting oxygen into the lungs lets you run faster and longer with training. But equally important is the strength factor. Strength is especially important as a person gets older. Falls are one of the main reasons for injuries and even death among older populations. Keeping up leg strength to regain balance after tripping is very essential. Having enough arm strength to catch the body and prevent a hard fall is also important.
There are four common sources of exercise to use to increase strength. One is using the weight of your body for resistance, a second is using weights as resistance, a third is using rubber or steel cables to offer resistance, and a fourth is an isokinetic machine for exercise. Each has a positive effect and each has a negative factor when using one method versus the others.
Bodyweight exercises (calisthenics) is the cheapest and is always available. By adjusting the angle of the body a person can change the resistance. As an example, when doing a push-up on the floor, if the head is higher than the feet (like putting the hands on a flight of stairs), the resistance is lighter. And having the feet higher than the head (feet on a chair) will increase the resistance. If doing a squat motion for leg strength, a person can hold a pole for balance and try squatting with one leg in the air for more resistance. One limitation is that the resistance is limited by the weight of the body.
