Just wondering if anyone with a better idea of training can help me decide what I should be concentrating on more in the gym.
I want to lose weight and don't mind getting on the treadmill however have had a couple of people say I should aim to just run solidly at a constant pace (slight variation) and some people telling me interval training on a treadmill will burn fat quicker.
I'm not marathon runner and can barely manage 10KM but take these for example which would be better for me the lose weight
Ex 1) Interval sprints for 30 mins - 1min @ 6.5KM and 2min @ 10.5KM
OR
Ex 2) Constant run for 30 mins - starting at 9.0KM upping to 10.5KM over the 30 mins.
Now am I right in thinking that the constant run is going to be better for me in terms of fat loss over the 30 mins and the interval would only be better if I did it for longer?
If you are running for a constant time but one event is faster, then the faster event will burn far more calorie, and hence fat. that is a very unfair comparison because your interval training is a far harder work out than your constant run.
When people talk about a fat burning zone, they mean an exertion level where a majority of the energy required can come from fat. Using fat as an energy source requires more oxygen than glycogen, therefore to exercise harder/run faster you have to use more glycogen since you don't have sufficient oxygen for fat alone. However, even when running faster you aren't burning less fat, you are burning about the same but the additional energy comes from glycogen.
Moreover, just because you are burning glycogen doesn't mean that overall you will experience less weight loss. After you have exercised your body will replenish glycogen stores, and will recruit stored body fat if the diet isn't sufficient in carbohydrates. Therefore, for your fixed 30 minutes of exercise intervals will lead to more rapid weight loss.
HOWEVER, the point about running slower is you can do it for longer and then the total energy expenditure is gong to be higher. You can only do your intervals for about 30 minutes, but you should be able to keeping running for at least an hour, and with training get that up to 90 minutes or longer.
I do a lot of running in the 90 minute range and will be burning 1000-1400 calories depending on pace. I could never ever burn close to that amount doing intervals.
Secondly, if you keep practicing long steady run at lower heart rates that get most of the energy form fat, then over time your body adapts to use higher proportions of fat even when running at higher exertion levels. this is one of the important adaptions required for marathon runners because you simply don't have enough glycogen storage to run a marathon, you have to recruit as much body fat as possible. Slow easy Running for 1.5-2 hours are especially good at training your body to use fat. As is said above, this doesn't directly help you, energy used form glycogen will balance it all out. however, if you body gets better at using fat for fuel then dietary fat is more liekly to be metabolized during daily activities.
This is in part why professional marathon runners have incredibly low fat %- they eat very little fat and what they do eat is very quickly metabolized and used for easy training runs and any other exercise.
One should also be careful that intervals have a much higher injury risk than slow easy running, so I would do no more than 1 interval set a eek, and take a break form it once a month. The rest of the time do other easy runs, or cardio work on a bike.rowing machine, swimming etc.
but to me, any INTENSE form of exercise (which HIIT certainly is) can be enough to put a beginner off the idea of exercise.
