Target Heart Rate Zone
Q: I am trying to lose weight and exercising five times a week, but the excess 10 pounds are not coming off. I keep hearing about exercising in your target heart rate zone, would I see better results if I did that?
A: It is very important to exercise in your target heart rate zone. The idea of no pain no gain, or, “I am not covered in sweat, I didn’t get a good workout” are erroneous.
First off, everyone’s target heart rate zone is different. You can estimate your target rate based on the old formula of 220 - your age. This will give you your maximum heart rate. To estimate your fat burning zone, take 75% of that number.
Your true target heart rate depends on a person’s training, genetics, and health conditions. I see many people for VO2 testing who are exercising past their target heart rate zone and not only gaining weight but also not improving on their performance. VO2 is a test that determines an individual’s fat burning zone and her anaerobic threshold.
To perform the test, I monitor a person’s oxygen intake, carbon dioxide output, and her heart rate throughout an exercise protocol. Oxygen is a direct reflection of the body’s ability to burn fat, and carbon dioxide is the body’s attempt to expel lactic acid from the body, which is the byproduct of glucose breakdown.
Fat is an unlimited energy source. Whether you have 5% body fat or 25% body fat, fat is the best source for sustained energy. The other main energy source people use when exercising is sugar, which is stored in the body as glycogen. The body stores glycogen in the muscle and liver, and can only store so much, approximately two hours worth. Glucose is for high intensity exercise, where you need a quick release. However, it burns up fast; sprinters utilize lots of glucose for energy.
We always burn some glucose when working out, but once we reach our anabolic threshold, we burn pure glucose. To break down fat, the body needs oxygen, thus we only burn fat in our aerobic zone. Once the anaerobic threshold is reached, the body can no longer bring in enough oxygen and utilize it to break down fat, so we switch to breaking down glycogen.
Now, here is the rub. If you are working out past your anaerobic threshold and burning through your glycogen reserves, your resulting blood sugar is low. So you’re done working out, and your blood sugar is low, which your body interprets as hungry. So you eat. You did just work out, you deserve it, right? When you eat, you increase your blood sugar, but now you are no longer working out, so all those excess calories go to replacing your depleted glycogen stores and what is leftover is stored in your fat cells. Why not burn mostly fat? Your blood sugar doesn’t drop so you don’t pig out, and you have just gained the most out of your workout.
It seems too easy, but in the case of trying to lose weight through exercise, taking it down to your fat burning zone is going to give you the best results. Of course, a healthy nutritional diet is essential not only for weight loss but to give you the energy to exercise.
— Lindsey Nelson
Food for Fall
Q: I was wondering if my diet should change with the seasons. Are there foods that are good for the fall?
A: In Chinese medicine the diet does change with the seasons. Fall is when the energy of the trees returns to the ground. Trees are wood energy which relates to the liver, so fall is a good time to support liver function. Foods that help the liver include beets, artichoke, garlic, and onions. As the weather turns cold and damp, it is a good idea to avoid cold food, especially first thing in the morning. Start with a nice warm bowl of oatmeal supplemented with nuts and raisins to warm up the digestive track and get the fires going for the day. Cold, damp days are also a good time to turn up the spice in your meals with ginger, garlic, cayenne, and black pepper. Herbs teas should also contain warming herbs like ginger, rather than cooling herbs like peppermint. Foods that are cooling like raw fruits and dairy should be decreased. Try to stay with fruits and vegetables that are available locally and in season. Fall is a great time for squash, pumpkin, and root vegetables like parsnips and turnips. Luckily Portland, OR has stores like New Seasons Market and Food Front Co-Op that support local farmers. So as the leaves change to their glory in the fall, think about changing your diet as well to stay in tune with the planet and your physiology.
— Arianna Staruch
This Issue’s Experts
Lindsey Nelson, ND, is a naturopathic primary care physician and can be reached at 503-279-0205 or lindseyn@clearh2o.org.
Arianna Staruch, ND, is a naturopathic physician focused on women’s health issues and can be reached at 503-279-0205 or arianna@clearh2o.org. |
