Weight loss is a fringe benefit of aerobic training--the true value lies in the physiological training effects induced by consistent cardiovascular exercise! The following looks like a list of boring medical terminology but it translates into a well-oiled & efficient biological machine—your strong body! These effects are not just during exercise, but around the clock!

Checking your heart rate during aerobic exercise is best done with a heart rate monitor. They are really cheap anymore and you wear them on your wrist like a watch. A heart rate monitor allows you to keep moving while you check your pulse; manually checking your pulse requires that you stand still and if your heart rate is at an aerobic level—suddenly standing stock still can drop your blood pressure and make you dizzy.
When beginning an aerobic session, always allow the first 5 or so minutes as a warm-up (just move a bit slower at whatever exercise you are going to perform). This gives the body time to warm up the muscles & joints and increase blood & oxygen flow to working muscles. After that, pick up the pace and begin monitoring your THR. When you are done, give it 5 more minutes at a slower pace for a cool down—this allows the heart rate to return to a slower pace—remember, stopping suddenly can have ill effects on blood pressure.

• Cardiovascular benefits: Your heart is a big muscle and aerobic training strengthens it and increases its ability to contract stronger. Stronger cardiac muscle increases stroke volume (amt. of blood pumped in one beat) and increases cardiac output (amt. of blood pumped in one minute). This translates into quicker & increased delivery of nutrients and oxygen being delivered to the body.

• Bradycardia (decreased resting heart rate): Due to the cardiac efficiency brought on by the improvements listed above, the heart now pumps more blood in fewer beats thus placing less demand/stress on the heart.

• Increased pulmonary function: (increased breathing efficiency) Aerobic training increases the rate and depth of breathing in order to provide more oxygen and faster removal of carbon dioxide. Aerobic training strengthens the muscles involved with respiration; the lungs become stronger and more elastic--more efficient at extracting oxygen from the air. As a result, less air has to be inhaled to provide the needed oxygen (resting or exercising), once again placing less demand on the body (lungs). You will notice this training effect with each aerobic session--breathing becomes easier and less like gasping for air.

• Increased oxygen delivery to working muscles: As muscles become aerobically trained, new capillary growth increases the amount of blood going to the muscles; therefore, oxygen delivery is increased. Also, muscles contain myoglobin--a protein compound for storing oxygen (much like hemoglobin, which carries oxygen in the blood). Myoglobin aids in the diffusing of oxygen to the muscle. Aerobic training stimulates an increase in myoglobin sites within the muscle; thus, muscles become better at extracting more oxygen from the blood, thus putting less demand on the heart & lungs to increase the blood flow. It helps the muscles to perform better with less fatigue.

• Increased ability of the muscles to utilize fat for fuel: (yea! Gets my vote): Glycogen (carbohydrate) is the body's preferred source for fuel; however, aerobically trained muscles develop a glycogen sparing effect (because the body wants to preserve its preferred fuel source) and switch over to burning fat. How? Aerobic exercise increases the number of oxidative enzymes within the muscle—these enzymes break down fat for fuel. (Note: there is no pill on the market that’ll make your body burn fat for fuel or specifically target “belly fat”--SAVE YOUR MONEY!!)

• Increased Stamina: Muscles contains microscopic organs called Mitochondria. These tiny organs turn fuel into energy. Aerobic exercise increases the number of mitochondria in the muscles. The more of these little “power houses” you have, the more energy your body can produce.

• Improved Glucose Tolerance and Reduced Insulin Resistance: Exercise makes the muscle tissues more sensitive to the action of insulin. This allows the muscle cells to uptake & store circulating blood sugar/glucose as fuel/glycogen—for present activities and for later use.

• Increased anaerobic threshold: Remember the old phrase, “Feel the burn”? The “burn” is caused by an accumulation of lactic acid--a byproduct of chemical energy production. The anaerobic threshold is the point at which lactic acid accumulation causes muscle failure--you just can’t continue the exercise. Aerobic training raises that threshold so you can work longer and stronger.

• Body composition changes: Aerobic training can decrease total body fat (adipose tissue) when combined with healthy eating habits (and if necessary, reasonable calorie restriction). There are increases in lean muscle tissue, but these increases are limited with aerobic training alone (resistance training is also necessary).

• Benefits to connective tissues:
     A. Stronger bones--Because aerobic training is not always “weight-bearing”, bone density improvements are related to the intensity of the exercise. Intense forms of exercise such as jogging, running, and hi-impact cardio classes can stimulate increases in bone density of the lower body & spine (the upper body needs to be targeted with specific weight-bearing exercises). Low intensity activities such as slow walking or low weight-bearing exercises such as using Stair climbers, Elliptical Machines or swimming are not weight-bearing enough to stimulate bone tissue growth.
     B. Stronger ligaments & tendons--aerobic training can increase the tensile strength (the amount of longitudinal stress that can be endured before tearing occurs) of ligaments and tendons; it can also increase the strength of tendons’ attachments to the bone; thus greater stresses can be tolerated with less chance of injury. 
     C. Thicker cartilage--aerobic training can increase the thickness of cartilage in healthy joints. How? Cartilage is avascular (has no blood supply); cartilage gets its nutrients from the synovial fluid surrounding the joint. The passage of synovial fluid through cartilage is much like the way water is sucked into & squeezed out of a sponge--it requires movement. As joints are moved (with a bit of exercise-induced pressure), this fluid is diffused in & out of the cartilage--nourishing it, thickening it. So note: a reason you should not lock out your joints—the constant pressure presses the synovial fluid out and holds it out.

• Decreased blood pressure: The precise mechanism for the aerobic training effect on lowering blood pressure is uncertain but could be attributed to better renal functioning which helps the body eliminate sodium, thus reducing the fluid volume of blood--reducing pressure against the inside of artery walls.

• Decreased cholesterol & triglyceride levels: Aerobic training only has a slight effect on LDL (bad cholesterol--clogs the arteries); however, it elevates levels of HDL (good cholesterol--gobbles up LDL’s). These cholesterol changes are thought to be related to enhanced ability of the body (through aerobic training) to clear triglycerides (fat) from the blood.

So you see, training aerobically shouldn’t be about striving for the “ideal” body (those don’t exist short of plastic surgery)--appreciate it for the health benefits that will improve the quality of your life; the fringe benefit is that you’ll trim up in the process! Learn to love the skin you are in.