When you look at the world-class long distance runners, you notice that every single one of them has minimum amount of fat. Next, check out the cycling event Tour de France, you will also fail to find any fat cyclists there. Even when you look at the competitive walking events at the Olympics, again you will have a hard time to find any fat people. Why is it so?
The common theme for these exercises is that they are all Cardiovascular Exercises. In this page, I would like to explain to you why Cardiovascular Exercise is the most effective way to lose fat and how to maximize fat loss while doing it.
To understand Cardiovascular Exercises, we need to first understand the word Cardiovascular. Here, Cardio- stands for heart and -vascular stands for the respiratory system. Cardiovascular Exercises are by definition exercises that involve your heart and respiratory system. For the sake of convenience, from now on "cardio" will be used to refer to Cardiovascular Exercises.
Your respiratory system takes oxygen in. Oxygen then enters your the blood stream in your lung. Then red blood cells in the blood carry oxygen from your lung to the tissues that need oxygen to oxidize the macronutrients stored in your body for energy.
As we learned from the Exercise Physiology page, we learned that to do any type of exercise that lasts more than a few seconds, the exercising muscle needs oxygen to burn the carbohydrate and fat stored in it. The longer the duration of the exercise, the higher proportion of energy coming from the Aerobic Energy System. This means that our Cardiovascular System is used more at prolonged exercises. Therefore, it is not surprising that research showed prolonged exercises can make our Cardiovascular System run more efficiently (ie higher percentage of energy comes form our Aerobic Energy System than untrained subjects). [FM04]
Heart Rate is found to be in positive relationship with exercise intensity. This is not surprising given the more you work your muscles, the more nutrients/oxygen you need to transport to your muscles to replenish nutrients/oxygen lost during exercise. Our heart serves as a blood pump. The more blood it pumps the more nutrients/oxygen can be carried by blood to reach the muscles.
The rate blood you can pump (aka Cardiac Output) is the product of two parameters: 1) Heart Rate (ie the pumping frequency); and 2) Stroke Volume (ie the pumping volume per heart stroke). Stroke Volume is determined by your muscle strength of your heart. Therefore it is more or less fixed unless you train your heart. Since Stroke Volume is more or less fixed at the moment, to increase your Cardiac Output to meet increased body needs, Heart Rate has to increase accordingly.
While your heart rate is increasing when you work harder and harder, there exists a point where your Cardiac Output is so high that your Respiratory System can't take in enough oxygen to fill up your red blood cells. It is obvious that after this point, it is not possible to further increase your exercise intensity. We call the frequency of stroke at this point Maximum Heart Rate (HRmax). For the heart rate at rest, we call it Resting Heart Rate (HRrest).
For a healthy individual, Stroke Volume is determined by how strong your heart muscle is. The more powerful it is, the bigger the Stroke Volume. Therefore, for people who are well trained in Cardiovascular Exercises, they will have bigger Stroke Volume. When you compare these people to others who has about the same Resting Metabolic Rate, you will find that these trained people has a slower Resting Heart Rate.
Resting Heart Rate can be easily measured by counting the pulses at the artery near the thumb side of your wrist or by using a heart rate monitor. To be accurate, please make sure you do this measurement the first thing you wake up in the morning and count it for one minute. For Maximum Heart Rate, the most definite way is to use Electrocardiogram (ECG). Since it is too costly to perform such a test, people usually just use a simple formula to estimate it. According to a 2002 study [RL02], the most accurate forumla is, HRmax = 205.8 - (0.685 × Age) which comes from [IOSRDC94].
Usually, people train themselves cardiovascularly at an intensity that is roughly constant throughout the exercise. This intensity is defined to be a percentage of difference between HRmax and HRrest which is called the Karvonen Method. You can then choose a Target Heart Rate (HRtarget) to train using this formula: HRtarget = (HRmax - HRrest) × %Intensity + HRrest. For example, if you are age 30 and you want to work at 80% with a Resting Heart Rate of 70. Then your Maximum Heart Rate is 185.25 and your Target Heart Rate should be (185.25 - 70) × 0.8 + 70 = 162.2.
Here a simple calculator for you to find your Maximum Heart Rate and Target Heart Rate. Just type in your Age, Heart Rate at Rest and Intensity % and click Calculate.
Now you know how to calculate the Target Heart Rate but how can I make use of it? In the following sections, I will classify common cardios into different Intensity Levels based on Intensity%. To check what Intensity% you are at while exercising, check your heart rate at the time and use the above calculator to translate into Intensity%.
Low Intensity Training refers to training at the lower end of training intensity, ie 60-70% intensity. At this intensity, you should feel like you are on a leisure walk. You can easily hold a conversation with another person.
The main benefit of LIT is that it is very easy. Almost everyone can do it without any training. It is recommended that you start with this if you don't exercise regularly before. Another advantage is that at this intensity level, you will burn higher percentage of calories from fat than at higher intensity (but the absolute amount of fat burn may or may not be higher depending on your fat burning capability).
Moderate Intensity Training refers to training at the intensity range of 70-85%. At this intensity, you should have a harder time to talk to people. Your breathing should be faster and heavier than before because more oxygen is needed.
In contrast with LIT, MIT is harder. You will burn more total calories than LIT for the same amount of time but with lower percentage of that from fat. Also, it will be harder for you to sustain at this level very long as higher ratio of anaerobic respiration causes you to fatigue earlier.
It is natural to think that what's left is High Intensity Training at 85% or more Intensity. However, for the majority of people, this is not really doable for any prolonged period of time. To maintain this high intensity, you need to rest in between periods of very high exertion. This practice of alternating low intensity level with high intensity level is called Interval Training. If the high intensity level is in the 85% or above range, then this is called High Intensity Interval Training (HIIT).
Before you attempt any HIIT, please make sure that you had been training with MIT for a while already. This is because HIIT is very high impact, if you start off untrained, you can injure yourself.
Here is a 30-minute routine to perform HIIT. First, start it off slow for 5 minutes. Then rush at 90% of your max heart rate for 1 minute. Then go slow for the next minute such that your body can replenish the PCr, oxidize the lactic acid from anaerobic respiration or convert it back to glucose. Next, return to full force for the next minute and then go easy for the next. Repeat this eight more times such that you do go all out for a total of 10 minutes. At the end, spend 5 minutes to go slow and cool down.
HIIT has the advantage that in addition to training your cardiovascular system, it also trains your leg muscles. The leg muscles you build can then be used to burn calories while you are at rest as each kg of muscle you gain burns 22kcal/day. Because of this muscle effect, HIIT is found to be more effective in burning fat than the other cardio trainings for people with little leg muscle to beign with. Note that if you have been doing weight training with your legs already, this added benefit of HIIT is minimal.
A big disadvantage of HIIT is that you are very likely to feel sore after each session, so you might need to rest at least one day before your next HIIT. It ends up. Another disadvantage is that due to its high intensity, almost all your calories will be from carb and very little from fat. Therefore, to do HIIT regularly, you need a high carb low fat diet.
Reaserch shows that regular cardio training can promote oxidation of fat stored in muscle from 30% of fuel source to 60% during cardio. [EEP00] To attain this training effect, it is found that you need to do cardio at least three times a week. For each session, you need to work at 70-80% (MIT) of your Max Heart Rate for 20-30 minutes or 60-70% (LIT) of your Max Heart Rate for 45 minutes or more. To achieve the aforementioned fat burning efficiency, you need to perform this program for at least six weeks. [EEP00] [FM04]
Since our goal is fat loss, I would recommend that you at least meet the requirements to produce the fat burn training effect. Therefore if you have time to do three sessions of 1-hour cardio every week, then you can do LIT. Of course the more sessions you do per week the better. If you have time to do three sessions of 30min cardio every week, you can try MIT. Again, the more you do the better. If you are short of time that you can only at most spend three sessions of 30min every week but you want the maximum fat loss and don't mind having sprinter's legs, then you can try HIIT. Note that this is just a rough guideline, you should adjust it to your own specific situation.
Weight-bearing exercise means when you are exercising, you work your bones and muscles against your weight caused by gravity. Examples are running, walking, etc. The benefit of weight-bearing wexercises is that it can train your bones to become stronger. Regular weight-bearing exercises can prevent osteroporosis (ie bones are susceptible to fracture) in advanced age. Examples are running, walking, etc.
Non-weight-bearing exercie means your weight is supported by something else (e.g. by parts of a cardio machine or water in swimming) are more suitable for highly obese persons who had difficulties doing weight-bearing exercises. Examples are stationary bike, swimming, etc.
Running on Treadmill is a high impact weight bearing exercise. On average, the impact on your legs is about three times your body weight. [EP01] To protect your knee joints, you are recommended to wear kneepads. To minimize the impact, you can also adjust the platform at an inclined angle (ie uphill). Running on Inclined Treadmill is better than running uphill outdoor because you don't need to go downhill afterwards. Running downhill wears down your knees greatly and you should avoid doing it regularly (by that I mean almost daily at an MIT level). Running on Treadmill daily with high intensity is not recommended for fat loss because of the wears on knee joints. It can also cause injury. I have seen several people who fell on their treadmills and it wasn't pretty.
This is very similar to Running on Treadmill but at a much lower impact. On average, the impact on your legs is about 30% of your body weight. [EP01] Again, inclined platform can reduce the impact but the difference is not big. It is recommended for people who can't exercise at a higher intensity based on their curent fitness level.
Stairmaster was designed in the 1980s to provide a lower impact cardio exercise than running on the treadmill. Unfortunately, Elliptical Trainer invented in the 1990s is an even lower impact exercise machine. As a result, Stairmasters are gradually supplanted by Elliptical Trainers.
Elliptical Trainers are designed to replace the Treadmills by minimizing the impact on knee joints. Some Elliptical Trainers have handles that allow you to work your upper body simultaneously with your lower body. Since the more muscles involved in training, the more fat burning training effect you will have, As of now, in my opinion, Elliptical Trainer with handles is your best bet for fat loss if you are not highly overweight. If your Elliptical Trainer has no handles but instead you can adjust its slope, you should reduce to slope to the lowest because that can also work your calf muscles for more fat burning effect.
This machine simulates the cycling action except that you stay at the same place. Since it is non-weight-bearing, it is an ideal starting point for over-weight people.
For overweight people who feels uncomfortable about Stationary Upright Bike, they can try Stationary Recumbent Bike. Here, instead of standing straight, you are in a seated position. This seated position reduces strain on the neck, wrists, hands, arms, shoulders, lower back and sit bones. People who suffers from back pain or genito-urinary troubles are recommended to use this bike.
Now I have introduced several types of Cardio to you. But which one is the best for you?
First, if you have back pain, your best bet is with stationary recumbent bike or other cardios that don't put strain on your back (e.g. swimming). Then if you are over-weight and find difficulties doing weight-bearing exercises, then you should try the non-weight-bearing ones like stationary bike.
If you can do weight-bearing exercises, you should do it for your bone health. To pick a choohave bayou should pick a cardio that doesn't impact your knee joint that much. If you do high impact cardios almost daily, you can wear out the tissues at your knee joint. An overused knee can cause pain and injury that gives you trouble all your life. So high impact cardio like running should be avoided if you plan to do it very frequently. In contrast, low impact ones like stationary bike or elliptical should be preferred.
Next, if possible you should pick a weight bearing cardio over an non-weight bearing cardio because the former can strengthen your bones and prevent bone loss. However, if you are too heavy such that you can't perform the weight bearing ones, you should start with the non-weight-bearing ones until your weight is low enough for you to perform weight bearing cardios safely.
If you find that you can do weight bearing cardio, you should pick the one with the lowest impact on your knee joints. This is because our knee joints are prone to wear out if we constantly apply pressure to it. Also, you will find As of today, the lowest impact weight bearing cardio can be done on the Elliptical Trainers. No wonder they are very popular in the gym.
Warming up before cardio is highly recommended as it can reduce the chance of injury and improve performance. To do this, just do exactly the same cardio you are planning to do but at a low inensity. Usually this can be done by spending one fifth of your allotted time, e.g. first 12-min in 1-hour LIT or 6-min in 30min MIT.
Stretching is also beneficial in most of the time as it can improve your Range of Motion. However, you should avoid doing them right before you do HIIT. This is because stretching muscles can make them weak, this can be dangerous in exercises that requires maximum exertion. [FB03]
Human body has two compartments to store water: Intracellular Fluid (ICF, ie inside the cells) and Extracellular Fluid (ECF, ie outside the cells, e.g. in the blood). These two compartments are separated by cell membranes. ICF contains potassium salt while the ECF contain sodium salt. By controlling the concentration of salt in these two compartments, our body can redistribute water content in ICF and ECF.
The physiology behind this is that, for example, if the ECF sodium salt concentration increase due to loss in ECF water or gain in sodium salt, then water in ICF has to come out of the cells to enter ECF such that salt concentration reaches an equilibrium. The opposite happens when we lose ECF sodium salt or gain ECF water. (As to why the potassium salt is kept within ICF, this is because cell wall has Potassium-Sodium pumps that move potassium to ICF and keep sodium in ECF.) [EMP03]
During prolonged cardio, our body sweats and we loses both water and salt in the process. Note that sweat is hypotonic (ie contains less salt) relative to ECF. In most cases, water is good enough to rehydrate when our kidney can process the extra water readily But in the case of prolonged vigorous exercises like Marathon, salt loss is substantial. If you drink too much pure water that goes beyond your kidney's capability, excess water can go into ICF and causes cell ruptures and sometimes death. That's caled Water Intoxication. In this case, isotonic (ie contains same salt concentration as ECF) drink is preferred. In fact, your body can drink 250ml of isotonic drink (0.9% sodium salt water), your body can retain almost the whole 250ml of water. Whereas if you drink 250ml pure water, your body can only retain about 100ml and the rest will be excreted as urine. That's why you see that post-operation patients who lost a lot of water are usually rehydrated with salt water instead of pure water. [EMP03]
If you are planning to do prolonged cardio that burns a substantial amount of carb stored in your muscle (e.g. 1.5 hours of running), you might consider to rehydrate yourself with sports drink while you are exercising. Research showed that there is a performance bounce when you rehydrate yourself with sugar-rich sports drink at the one hour mark of a two-hour cardio. [EP01]
However, if you are not going to do prolonged exercises or you are going to have a meal soon after exercise, drinking sugar-rich sports drink can only make you consume extra calories that derail your fat loss effort.
You should do cardio right before you have a meal. The reason is that you can replenish the salt you lost during sweating as well as the muscle glycogen you used up during exercise. The added benefit is that some of the carb you eat at the meal will be taken up by muscle instead of being burned in lieu of fat.
If you have been following to the diet I proposed in the Diet page, I would recommend you to add carb calories to the diet such that you offset what you spent in cardio. For LIT, multiply the calories count on your cardio machine by 0.4. For MIT, multiply it by 0.7. For HIIT, multiply it by 0.9. Then add the product to carb calories count in that diet. For example, suppose you burn 600kcal in the 1 hour LIT you did, then you add 240kcal of carb calories to the diet. This should make sure that you have a non-negative carb calories balance.
If you are not following my diet, then you can still do the same math and then check to see if your carb intake has satisified the new requirement or not.
I hope now you have a basic understanding of how to design a cardio program that can maximize your fat loss. Should you have any questions or comments regarding the content of this page, please feel free to let me know. I hope one day you will lose enough fat to look more like a world class runner! ;) Happy Fat Loss! :)