Jogging is a higher impact activity than walking. Jogging requires that both feet must be off the ground for a split-second during every stride. Because joggers become airborne, their impact with the ground is greater and the expenditure of energy is higher than that of walking except under two circumstances.

1. The energy expenditure or oxygen cost of very slow jogging (5 mph) is equal to walking at the same speed. At speeds faster than 5 mph, the oxygen cost of walking exceeds that of jogging because of the inefficiency associated with very fast walking.

2. The oxygen cost of jogging up a hill is about half that of walking up the same hill at the same speed. Both feet come off the ground during jogging, so some of the vertical lift needed to run up the hill occurs naturally, thereby lowering the net cost of the vertical work.
[Read more...]

Protein is an essential nutrient that yields approximately 4 calories per gram. Its energy is liberated for:

1. Building and repairing body tissues
2. Forming enzymes, hormones, antibodies, and hemoglobin
3. Transporting fats and other nutrients through the blood
4. Maintaining the acid-base balance in tissue fluids
5. Supplying energy for muscular work when there is a shortage of carbohydrates and fat.

Proteins are complex chemical structures containing carbon, oxygen, hydrogen, and nitrogen. These elements are combined into chains of different structures called amino acids. The proteins of all living tissue consist of 20 different amino acids. Two other rare amino acids have been identified but are found in very few proteins. Nine of the amino acids are considered essential because the body cannot manufacture them and they can be obtained only through the diet.

Complete proteins contain all of the essential amino acids. A high-quality protein is a complete protein that has all of the essential amino acids in amounts proportional to the body’s needs for them. Meat, fish, poultry, and dairy products are high-quality proteins. Incomplete proteins do not contain the amino acids in the proportions the body needs. [Read more...]