Cardiovascular exercise has received a lot of attention over the last 15 years as the centerpiece of physical fitness, weight management, and cardiorespiratory (heart and lung) health. The terms cardiovascular exercise, cardiorespiratory fitness and aerobic exercise are all synonymous. This kind of exercise requires large muscle movement over a sustained period of time, elevating your heart rate to at least 50% of maximum level. Examples include walking, jogging, biking, swimming, and any other repetitious activity that can be performed over an extended period of time.

Cardiovascular exercise has numerous benefits. They include a decreased blood pressure, increased HDL (good) cholesterol (high-density lipoproteins responsible for removing LDL (bad) cholesterol from the cells in the arteries and transporting it back to the liver for removal from the body), decreased LDL cholesterol, decreased body fat, decreased glucose-stimulated insulin secretion (this increases capillary density and blood flow to active muscles), increased heart and lung function and efficiency, and decreased anxiety, tension, and depression.

All of these benefits combine to help lower your risk of cardiovascular disease by reducing risk factors like obesity, hypertension, and high blood cholesterol. In addition, cardiovascular exercise serves as a foundation for the activities of daily living, sports, and other outdoor activities. Activities such as tennis, golf, skiing, dancing, basketball, volleyball, boxing, hiking, and strength training programs all benefit from cardiovascular exercise. Your enjoyment of day-to-day and physical activities will also greatly benefit because you will have more stamina, less fatigue and less risk of injury. However, there are several precautions you should take to help maximize exercise safety.

Post-meal Exercise
Cardiovascular exercise soon after a full meal can compromise oxygen and nutrient delivery to the working muscles, and cause gastric discomfort. Thus, you should wait at least 60-90 minutes after a full meal before engaging in cardiovascular exercise. The level of exercise and the amount and type of food consumed affect the time required for digestion to be completed before beginning exercise. The higher the exercise intensity and/or the greater the amount food consumed, the longer the time should be between eating and exercising.

Exercising in Hot Weather
Another factor that increases the risk of injury and complications is exercising in hot weather. The following are guidelines to prevent heat stress:

1. Allow 1-2 weeks for acclimatization to a hot environment

2. Avoid training in the hottest part of the day, usually between 10 a.m. and 4 p.m., during the summer.

3. Drink water before, during and after exercise. During prolonged cardiovascular exercise, drink 4-6 ounces of fluids (preferably water) every twenty minutes.

4. Wear loose-fitting clothes that allow for evaporation of sweat.

5. Decrease training intensity by monitoring heart rate in hot environments.

6. Take a 10-15 minute rest for every 45-60 minutes of physical activity.

7. Give special consideration to, and use caution if you are a heat-sensitive person (obese, unfit, history of heat stroke, etc.).

Pollutants
Pollutants can also have adverse effects on the body. This is of concern if you exercise outdoors in or near big cities. Some common ones include ozone, carbon monoxide, and sulfur dioxide. The most problematic of these pollutants is ozone, or smog, which is caused by the combination of ultraviolet light and emissions from internal combustion engines. Ozone exposure may impair lung function during cardiovascular exercise. Carbon monoxide is another common air pollutant that can reduce exercise safety and effectiveness. This is caused by exposure to crowded freeways or smoke filled rooms. Sulfur dioxide is not a major irritant for most people, but those with asthma or bronchospasms tend to be adversely affected by it.

Cardiovascular exercise provides many important benefits that cannot be achieved by any other exercise or activity. Cardiovascular exercise is also very convenient; you can do it in the outdoors or inside while watching television or reading a book. However, when enjoying this great form of physical activity, be sure to adhere to these precautions so that your program is not only effective, but safe as well. Good luck: I hope you enjoy all the wonderful benefits of a safe and effective cardiovascular exercise program.