Calories burnt during the activity do little to help us lose fat. The critical component of successful fat loss relies on our metabolism and certain hormones flowing through our body. This is why shorter more intense workouts are much more efficient.
Training at a lower intensity burns calories only during the activity. As soon as you stop you will stop burning calories. This is because this form of training hardly raises your metabolism. Also longer, less intense cardio sessions hardly stimulate our body to release hormones which will help our fat loss progress. If done long enough though, you can actually stimulate a hormone that works against us...cortisol. Cortisol is a catabolic hormone which actually eats away at muscle. This is obviously a bad thing!
On the other hand, shorter, more intense cardio workouts release certain hormones, most importantly Growth Hormone. The amazing thing about growth hormone is that it helps us build muscle, and does its best to stop fat from storing on our body. We could eat as much as we want and we won't put on any fat. (However if you got an absolutely voracious appetite, you might, at worst very slowly put on some fat.) That's why if we got the hormones flowing in abundance in our body, an occasional pig out day, or binge isn't going to hurt our progress.
Another great benefit of intense training is that it raises our metabolism substantially, for up to 48-72 hours afterwards. Seeing how it keeps the metabolism elevated for up to 3 days afterwards, imagine what would happen if you did these cardio workouts every other day. Your metabolism would be like a fat destroying furnace!
* Myth: Exercise done at a low intensity, such as walking, is better at fat burning than other high-intensity activities, like running or cardio activities where you push yourself very hard.
The Truth: In a strict scientific sense, these claims are true because working at a lower intensity requires less quick energy and a higher percentage of fat is burned. But you'll also burn fewer calories than you would if, for the same amount of time, you work out at a harder intensity (running versus walking). If you're trying to lose weight, even though a higher percentage of fat is being used, a lower total amount of fat is lost.
Whether increased fat burning will result in actual weight loss is dependent upon several variables, including the total calories burned (which include both fat and carbohydrate calories) and the total fat calories burned. If you do work at a low intensity, you need to increase the time spent exercising to burn more calories. What matters most is the total number of calories burned. If you burned 250 calories every day from a short, fast jog, you'd see a bigger difference in weight and fat loss than if you walked everyday for the same amount of time. The number of fat calories you burn isn't that important, because even if you burn a lot of carb calories, these need to be replaced both by the carbs you eat in your diet and also within your body. Your fat stores will be broken down and transformed into carbohydrates when you need fuel. Even if you're burning lots of carb calories and less fat calories through exercise, your fat still inevitably gets used.
It boils — not burns — down to this: During the same amount of time you don't use more calories at lower exercise intensities. If you're trying to lose weight and you have only 30 minutes to work out, you would burn fewer calories walking at a moderate pace compared to walking at a fast pace. Working out at higher intensities may cause you to burn a lower percentage of fat, but since you burn more total calories, you still use more fat calories.
Low- to moderate-intensity exercise can burn a significant number of calories over a period of time. If you aren't fit enough to push yourself to work at a high intensity, or you have a physical weakness that prevents you from doing so, you can still burn a lot of calories by doing low-intensity workouts for a longer period of time.
Read more: http://www.dummies.c...l#ixzz0vbkMrU9P
. A study by Gibala et al. demonstrated 2.5 hours of sprint interval training produced similar biochemical muscle changes to 10.5 hours of endurance training and similar endurance performance benefits. According to a study by King  , HIIT increases the resting metabolic rate (RMR) for the following 24 hours due to excess post-exercise oxygen consumption, and may improve maximal oxygen consumption (VO2 max) more effectively than doing only traditional, long aerobic workouts.
Long aerobic workouts have been promoted as the best method to reduce fat, as fatty acid utilization usually occurs after at least 30 minutes of training. HIIT is somewhat counterintuitive in this regard, but has nonetheless been shown to burn fat more effectively. There may be a number of factors that contribute to this, including an increase in RMR, and possibly other physiological effects.
High-intensity interval training has also been shown to improve athletic performance. For already well-trained athletes, improvements in performance become difficult to attain and increases in training volume can potentially yield no improvements. Previous research would suggest that, for athletes who are already trained, improvements in endurance performance can be achieved through high-intensity interval training. A recent study by Driller showed an 8.2 second improvement in 2000m rowing time following 4 weeks of HIIT in well-trained rowers. This equates to a significant 2% improvement after just 7 interval training sessions. The interval training used by Driller and colleagues involved 8 x 2.5 minute work bouts at 90% of vVO2max, with individualized recovery intervals between each work bout.
Recently it has been shown that two weeks of HIIT can substantially improve insulin action in young healthy men. HIIT may therefore represent a viable method for prevention of type-2 diabetes.
Long Duration, Low Intensity Exercise
Going for long runs or walks, time spent on treadmills, bikes, rollerblades , gym classes – and all exercise where we spend a lot of time doing (think 30 – 60 minutes) not challenging our body the whole time and not breathing heavily.
* Helps your cardiovascular system – heart, blood vessels and lungs
* Creates circulation into your brain
* Good for blood pressure and cholesterol
* There are several benefits to long duration, low intensity
* Gets your hormones working against you
* Cortisol levels go up because it causes long standing stress on your body and body stores more fat and breaks down more muscle
* Your appetite is stimulated
* Recover slower from exercise
Short Duration, High Intensity Exercise
Also defined as “Surge” or “Burst” Training or interval training. Performing a short surge in exercise, followed by a period of rest – then repeating.
* Hormones work in your favor
* Your body continues to burn fat and build muscle long after your workout
* Pushing your body to its maximum ability, not beyond it
* Testosterone and growth hormone increase
* Endorphin boost (fights depression and anxiety)
If you eat at a caloric deficit while lifting weights, you WILL lose fat and gain muscle. Of course, you will lose weight a lot faster if you add cardio, but lifting can achieve weight loss too. The fact that you use the word "tone" says a lot.
e: and what the hell, from another forum
Pretty much all you need to know. When you are working out at mod intesnity for longer durations (RER of ~0.8) you are burning fat as your energy source WHILST you are exercising. Where as during HIIT (RER 1.0), you are burning carbs as your main energy source WHILST exercising. After HIIT, you enter EPOC - and is when fats are utilised to replenish carbohydrate stores due to carbohydrate depletion/low levels as a result of HIIT.
high intensity cardio burns more calories due to the recovery needed increasing your metabolism for a prolonged period after due to something called "Excess Post-exercise Oxygen Consumption" it is widely criticised as a myth but the results of countless people speak for themselves.
just use the Olympic sprinter argument some of leanest guys in the world and all they rely do for training is flat out dash's.
the low intensity cardio taps into your fat stores more effectively for energy however you need to do about 1 and half hour to have same benefit as a good HIIT session