FitnessWise Personal Fitness Training and Post-Rehabilitation

Aerobic Exercise: Low Intensity or High Intensity?

by J.P. Montalván, M.S., C.S.C.S.
Executive Director, FitnessWise™

Clients, relatives, friends, people at parties and just about everyone on the street ask
us about the best way to burn body fat. The idea of exercise intensity -- low intensity
and high intensity -- and losing fat confuses almost everyone.

Let's start with the low intensity concept. Aerobic exercise uses two sources of fuel,
carbohydrates and fats. P.D. Gollnick and other researchers in the 1980s proved that
prolonged low intensity exercise derives most energy from fats, although
carbohydrates are also used as a significant fuel source. As intensity increases,
carbohydrate use increases and fat use decreases. So, simple logic would lead some
to believe that if fat loss is our goal, we should engage in low intensity aerobic
exercise rather than high intensity exercise.

Wisdom tells us that simple logic is often poor; here, simple logic does not account for
two things.

First, weight and fat loss are dependent upon the relationship of calorie expenditure
and calorie intake. If we expend more calories than we take in, we lose weight. In
other words, our caloric deficit is responsible for weight loss, not whether
carbohydrates or fats are burned. Since our body stores nearly all energy as fat, energy
used by the body at a calorie deficit must be from fat.

In addition, aerobic exercise at high intensities uses more total calories per unit of time
than its low intensity counterpart. If we want weight loss, we want to select intensity
to achieve a caloric deficit. Several studies published in the Journal of the American
Dietetic Association confirms this -- fat loss depends on energy expenditure, not
exercise intensity.

Second, while the body uses a higher percentage of fat as fuel during low intensity
exercise, the total amount of fat burned is greater during high intensity training. Susan
Puhl and Kristine Clark at Penn State University illustrate this in the following example. A
woman burning 270 total calories, 160 calories from fat, walking 4 miles in 60 minutes,
could burn 450 calories, 180 from fat, jogging 4 miles in 40 minutes. We see she uses a
higher proportion of fat to total calories by walking, but she expends more total fat
while jogging. As a rule, high intensity exercise burns more total calories and more fat
calories than low intensity exercise if either distance or time are equal.

Puhl and Clark remind us that low intensity and high intensity exercise alike provide
health benefits apart from fat loss. In addition, low intensity work may be more easily
maintained than regular high intensity exercise. A certified fitness trainer in conjunction
with your doctor can help you decide upon an intensity that best fits your needs and
abilities.

As a guideline, the American Council on Exercise (ACE) suggests various methods for
deciding aerobic intensity. From among these methods, ACE suggests a range of 50 to
85 percent of heart rate maximum reserve (HRMR). Low intensity exercise includes work
at 50 to 60 percent of HRMR for beginners or people with low fitness levels; one of
average or high fitness levels would do low intensity work at 60 to 70 percent of HRMR.
Healthy adults with average or high levels of fitness would engage in high intensity
exercise at 75 to 85 percent of HRMR.

Again, a fitness trainer in conjunction with your doctor can help you decide upon an
appropriate intensity. Otherwise, you may overestimate or overestimate your needs
and abilities.

As we have discussed in other statements, aerobic exercise is not the only way to lose
fat. Studies, like one by Nancy Kay Butts and Sandra Price at the University of Wisconsin,
show a weight training program of as little as 12 weeks can lead to fat loss. A
well-designed aerobic and weight training program is your way to losing fat.

Do I Heat or Ice an Ouch?

by J.P. Montalván , M.S., C.S.C.S.
Executive Director, FitnessWise™

Ouch! We are all susceptible to pain, whether from injury or overuse. So, you limp onto
the sofa with a heating pad, right? Wait, you've got an ice pack, don't you? What to
do?

You may be surprised to know that even among clinicians, coaches and athletes, a
consensus on treatment can be difficult to find.

Overall, most experts seem to agree that the use of cold, or cryotherapy, is the more
effective treatment for reducing tissue inflammation in the first 24 to 72 hours following
an injury.

"Cryotherapy acts to constrict vessels and slow enzymatic reactions. The cold speeds
recovery by reducing inflammation and works as an analgesic, or pain reliever, by
slowing nerve conduction and decreasing muscle spasm," says Margot Putukian, M.D.,
in the Penn State Sports Medicine Newsletter. Cold therapy is useful for all pain,
especially trauma, muscle spasm, and hemorrhage.

Tina Posey, L.P.T., C.S.C.S., in Training and Conditioning, recommends 20-minute ice
treatment applied three to four times per day during the first 48 hours. To avoid
frostbite, you can place a dampened paper towel on the skin under the cold source
and secure the pack with an elastic bandage. The elastic bandage will compress the
area and help reduce swelling by increasing pressure on fluids in the inflamed area
and forcing the fluids back into the body. Furthermore, you can elevate the injured
area above the heart to reduce blood flow to the injury and speed healing.

Heat, or thermotherapy, increases blood flow to an area, increasing the delivery of
oxygen and enzymes to injured tissue. Like cold, heat is an analgesic, but may be
more useful in treating strains, sprains and overuse injuries. After 48-72 hours and once
inflammation has subsided, you can continue to use ice or try heat therapy.

According to the Penn State Sports Medicine Newsletter, you must use a heat pack for
15 to 20 minutes to affect deep muscle tissue. To prevent burns, wrap a pack in towels
before applying it to your skin. When using a heating pad, use the low or medium
setting.

Lastly, you may need some follow-up care from an emergency room, an orthopedic
physician or your primary care doctor. And as mom used to say, an ounce of
prevention is worth a pound of cure. With a good strength training program, we can
develop muscle to enable us to move, shovel snow, lift suitcases, haul furniture,
reduce arthritis pain and -- most importantly -- prevent injury and pain that can
accompany activity when we least expect it.