If you can run …
… cycle, swim or perform any exercise for an hour then you have to ask yourself: Am I really giving myself a workout? Are you challenging your heart enough, your lungs, your body — are you challenging yourself — enough?
Do you ever sweat or feel wiped out at the end of your ‘workout’? I put the last in quotes because, really, if you are being honest with yourself, can you call breezing along for an hour on a treadmill or elliptical machine without breaking much of a sweat or feeling your lungs taxed for air, a workout?
Studies show that exercising at a high intensity for ten or twenty minutes will give you more health benefits than an hour of moderate intensity. You burn more fat too.
How is this possible? After your body has exercised for twenty minutes it has depleted all the energy that is quickly available and turns to burning fat but what that does, when you continue exercising for another forty minutes, is it teaches your brain that fat needs to be in ready supply for your next workout session so your body will store fat over the interim. When you stop at twenty minutes your brain thinks that a quick energy supply should be on hand for the next workout so it tells the body to burn fat in the interim so that energy is quickly available in the muscles.
Long periods of moderate exercise will make you lean but lean and fat(it sounds like an oxymoron but the expression ‘skinny fat’ was coined for a reason). Long periods of moderate intensity like those who routinely train to run marathons may employ will lose muscle over time. Interval training with short bursts of high intensity will let you become lean but strong with no muscle loss. In fact, every good interval training program includes strength training so your muscles become more defined.
The picture below is an extreme example but you get the idea.