Aerobic exercise for weight loss: Key points of heart rate, time, and interval training

Aerobic exercise for weight loss

Among the various methods of weight loss, exercise has always been highly recommended. Among the various types of exercise, aerobic exercise is widely recognized as the best healthy way to lose weight. Aerobic exercise refers to various low-intensity, long-duration exercises that involve sufficient oxygen during the exercise process. These include various aerobic exercises, as well as endurance exercises such as running, cycling, swimming, and rope skipping. It may sound a bit boring, and you may have tried them, but perhaps you didn't stick with them to the end because of poor results.

It's not that these aerobic exercises are ineffective or unsuitable for you. Generally speaking, unless there is a specific medical condition that makes the exercise unsuitable, aerobic exercise has a very good effect on improving cardiopulmonary function and losing fat for everyone. The key is to choose the type of aerobic exercise based on your original physical condition and your exercise interests, and to design an aerobic exercise prescription for yourself by combining the key points of aerobic weight loss.

Exercise and weight loss

Exercise is key to burning calories.

The human body's basal metabolic rate is generally less than 1000 kcal per day, although this number varies depending on body weight. The calories burned through physical activity, however, vary greatly depending on its intensity and duration. A person who is inactive burns about 800 kcal per day, while someone engaged in prolonged aerobic exercise can burn 5000-6000 kcal.

If you burn an average of 500 calories a day through physical activity for 22 weeks (154 days), you can burn 77,000 calories. Assuming each pound (454 grams) of fat contains 3,500 calories, this equates to burning approximately 10 kilograms of fat. Walking for just one hour a day can burn about 500 calories, which is both safe and easy to do.

Exercise not only directly consumes a large amount of energy, but more importantly, it increases the metabolic rate. Depending on the intensity of exercise, the metabolic rate can generally be increased by 15% to 50%. This increased metabolic rate allows the body to burn more energy under the same conditions. Furthermore, improved cardiopulmonary function helps to gradually increase the intensity and duration of exercise to burn even more calories.

Keywords for exercise for weight loss

1. Heart rate

Heart rate is the most direct indicator of the effectiveness and intensity of aerobic exercise. Many gym machines now have calorie counters. However, these counters generally differ significantly from actual calorie expenditure, and there is no constant ratio between calorie consumption and fat burning. Fat metabolism involves a series of complex biochemical reactions, and heart rate reflects the excitability of the sympathetic nervous system. Sympathetic nerve excitation promotes the secretion of a series of lipolytic hormones, thereby activating lipases. This causes fat stored in adipose tissue to break down into free fatty acids and glycerol. Under sufficient oxygen supply, fatty acids can further decompose into carbon dioxide and water, releasing a large amount of energy.

So, what heart rate or intensity should you aim for during exercise to effectively lose weight? Generally, it should be between 60% and 75% of your maximum heart rate (220 - age). For example, a 30-year-old's maximum heart rate is 220 - 30 = 190. 190 × 60% = 114, 190 × 75% = 145. Therefore, exercising with a heart rate between 114 and 145 is effective and safe. Since maximum heart rate is an estimate based on physiological limits, the actual intensity should vary from person to person. Beginners can usually maintain 60% to 65% of their maximum heart rate. Ignoring your physical condition and blindly pursuing high intensity is detrimental to your health.

2. Time

According to research in American sports medicine, muscle glycogen is the primary energy source for the first 15 minutes of aerobic exercise, while fat metabolism only begins to kick in 15-20 minutes after exercise. Therefore, aerobic exercise is generally required to last for more than 30 minutes. This raises the following issue: The required heart rate intensity (65% of maximum heart rate) can generally be reached when an adult woman completes an 800-meter run in 4-5 minutes or a man completes a 1500-meter run in 6-7 minutes. However, many people trying to lose weight may not have this level of physical fitness. Forcing themselves to complete this intensity and duration of aerobic exercise will lead to muscle fatigue. Many people who have tried aerobics may have had this experience: they lost weight, but were exhausted and lacked energy at work the next day, so they gave up after a short time. Therefore, we should not mechanically use research results as the premise for aerobic exercise prescriptions. Studies only provide average statistics; whether muscle glycogen can provide energy for 15 minutes depends on each individual's reserves. As mentioned earlier regarding lipolysis, the so-called activation of fat energy supply after 15-20 minutes of aerobic exercise only reflects the biochemical reaction time of lipolysis. Fat, unlike muscle-deficient glycogen, cannot directly provide energy to the body. This reaction time also depends on each individual's physiological condition. Therefore, exercise time should be increased gradually. The duration of continuous exercise reflects the body's endurance, and endurance cannot be improved in just one or two workouts. Of course, too short an exercise session will not achieve weight loss, because only when the body consumes the energy produced by fatty acid oxidation can it further promote more fat breakdown, thereby ultimately achieving weight loss.

How to resolve this contradictory issue? It's recommended that overweight individuals with poor physical fitness use interval training when starting aerobic exercise. Maintain a high heart rate (intensity) for a period until you begin to feel fatigued, then gradually transition to relaxing or slower exercises. Maintain a relatively high heart rate (moderate intensity) until you recover somewhat before moving to a high heart rate (high intensity). Avoid exercising when you are extremely tired. While this can test willpower, a gradual approach is healthier and prevents you from feeling exhausted after a single workout, making it difficult to cope with the next day's work. Exercising gradually for 45-60 minutes can be just as effective for weight loss as continuous exercise. Of course, interval training is a transitional method; the ultimate goal is to enable you to easily complete 30 minutes or more of high-intensity aerobic exercise. This will not only achieve weight loss but also significantly improve your endurance and cardiovascular function.

3. Oxygen

Fatty acids can decompose into carbon dioxide and water and release a large amount of energy under sufficient oxygen supply. Therefore, oxygen is the key to fat loss during aerobic exercise, and sufficient oxygen intake must be ensured during exercise. However, this does not mean that simply maintaining deep breathing during exercise will guarantee oxygen intake, because the amount of oxygen inhaled does not constantly correspond to the amount of air inhaled. If many people do aerobics together indoors, they are likely to experience oxygen deficiency. Therefore, it is best to do aerobic exercise outdoors or in a well-ventilated indoor environment.

4. Exercise intensity

The best way to lose weight through exercise is through low-intensity, long-duration aerobic exercise. This is because the activity of lipases, which catalyze the breakdown of fat in the body, generally only begins to increase after about 20 minutes of exercise.

Only by consistently engaging in low-intensity, long-duration exercise can you increase the proportion of energy derived from fat, reduce the accumulation of body fat, and achieve weight loss. Low-intensity exercise will not significantly increase muscle mass, but it does increase muscle strength and makes the body appear more proportionate. Obese individuals are more prone to chronic cardiovascular and metabolic diseases, making low-intensity exercise a safer option.

5. Motion frequency

For those without a fitness background, exercising twice a week allows sufficient time for the body to rest and recover. An effective aerobic workout can alter the body's biochemical reactions, allowing the body to adapt to a new metabolic rhythm during rest. After a period of time, the frequency can be increased to three to four times a week, depending on the situation. However, there is no need to go to the gym every day and exhaust yourself. The goal of exercise is to improve health and boost energy, not to make yourself overly tired.

Things to note when making an exercise plan

Those trying to lose weight should choose suitable exercises and develop an exercise plan based on their age, gender, work, lifestyle, environmental conditions, interests, physical strength, exercise experience, degree of obesity, and weight loss goals to achieve both weight loss and health benefits. Adjustments should be made continuously based on the results. The elderly, those who are frail, or those who are overweight should avoid fast-paced, high-intensity, heavy-load, and prolonged physical activities. Patients must exercise according to their doctor's advice. For safe, reliable, and efficient weight loss, it is best to engage in exercise programs where the intensity and load are entirely controlled by the individual.

As the saying goes, "Practice makes perfect." Three days without exercise will slow down your metabolism. To ensure sustained and successful weight loss, physical activity should not be inconsistent, neither too strenuous nor sporadic!

Exercise and Diet for Weight Loss

Intense exercise can cause blood sugar to drop too low. The brain and nervous system are unhappy with such low blood sugar, so they will make you want to eat a lot.

Feeling hungry after exercise indicates that some of your stored glucose (glycogen) has been depleted. Glycogen stores are naturally low, typically only enough for 12-15 hours without exercise. Even low-intensity exercise depletes glycogen stores. Our brains constantly monitor glycogen levels; if insufficient, they send signals to replenish it. This is why you feel hungry after exercise. If you don't eat, your brain will be unhappy; however, consuming too many carbohydrates will shut down your fat-burning system. Therefore, you should eat low-calorie, filling foods to quickly stop hunger and allow you to continue burning fat.

When a person gains weight due to overeating, three-quarters of the weight gain is fat, and the other quarter is muscle. This is because the body needs extra muscle to move excess fat (most of this extra muscle is located in the hips and legs). When a person loses weight and sheds fat, they also lose that extra muscle because they no longer need it. However, muscle is crucial for burning fat, so the rate of weight loss slows down after initial success-this is the plateau. So what should you do then?

If there were a way to lose fat while preserving muscle, then there would be no plateau. The answer is to do some weight training, such as push-ups, squats, or resistance exercises using equipment.

The prerequisite for any exercise is sufficient nutrition, and avoiding excessive carbohydrate intake. Exercise should not be stressful or forced. Exercising with a relaxed mind will make you feel healthier.

Don't forget to "cool down" after exercise:

Warming up is essential before any strenuous exercise to prevent muscle and bone injuries. Similarly, cooling down for a few minutes after exercise is also important; avoid sitting or lying down immediately afterward.

During strenuous exercise, blood circulation accelerates. If you suddenly stop, blood pools in the vessels below the waist, causing a drop in blood pressure. In severe cases, this can lead to insufficient blood supply to the heart, resulting in coma or even death. Studies show that a drop in blood pressure triggers the release of large amounts of adrenaline, sometimes up to ten times the normal amount. Adrenaline causes vasoconstriction, thus raising blood pressure. For some people, excessive adrenaline secretion can even lead to cardiac toxicity and heart disease.

Cooling down can also help test whether the amount of exercise is excessive. The correct approach is to walk or jog slowly for at least 5 minutes after doing moderate-intensity exercise such as running, swimming, or aerobics, and then count your pulse. If your pulse is still not less than 120 beats per minute (not less than 100 beats per minute for those over 50), it means that the exercise was too strenuous, and you should reduce the intensity in the future.

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