Basic Water Information
1- Buoyancy. If a person is in water up to their waist and they weigh 100 pounds, their weight is approximately cut in half or 50 pounds. If at chest level they would take off approximately 75% of their land weight (weighing about 25 pounds) and at neck depth their weight would only be 10% or about 10 pounds! What a gift water aerobics can be for our seniors with orthopedic problems!
2 - Resistance. Water provides between 11 and 12 times the resistance of air. Resistance is increased in two ways--
a) by increasing the surface of the body part, and
b) by increasing the speed of the body part going through the water.
NOTE: Since resistance of the water is a prime reason for doing water aerobics, why would instructors have participants do arm exercises with the arms out of the water for minutes at a time? Also, people who are taking water aerobic are doing so because they want (or need) to be in the water. Vertical Aqua jumps and leaps do have the arms coming out and/or over the head. Other than some of the jumps, I keep my seniors arms in the pool to have the water support their shoulders and to take advantage of the properties of the water. Better safe than sorry! As a rule of thumb keep all limbs in the pool!
3 - Heart Rate. In the water a person’s heart rate decreases approximately 13% or about 17 beats per minute. A useful chart is available in the Aquatic Fitness Professional Manual from the Aquatic Association. If you are using heart rate rather than Perceived Exertion to access cardio work levels you need to be aware that there is a lowering of the heart rate when in the water – also be aware of participants who are on medications that lower the heart rate.
4. Water Pressure. One of the effects of water pressure, besides lowering heart rates, is that it exerts pressure on the skin which assists in circulation. Deeper water can be helpful for seniors with conditions that cause their extremities to have poor blood circulation.