Physical fitness is today's hot topic. And everywhere you turn you hear something new. But is it all true?

The more you sweat, the more fat you burn

This myth has encouraged people to work out in extreme heat or wear layers of clothes or rubber or plastic weight-loss suits in the hope of sweating fat off. Unfortunately, it's water they're losing, not fat.

Fat burns when it is used as a fuel source for exercise, which doesn't happen initially. When you first begin to exercise, you burn carbohydrates or sugars. It takes about 20 minutes of easy to moderate aerobic activity before the transition from burning sugars to fat begins. (Aerobic exercise is any rhythmic and continuous activity that uses oxygen and large muscle masses of the body, such as the arms and legs. Examples are bicycle riding, jumping rope, walking, jogging, aerobic dance, and swimming.) So, to burn the flab, plan on working out at least 40 minutes.

If you stop working out, your muscles will turn to fat

If you decrease your activity and continue to eat the same or more, you may gain back that spare tire that you worked so hard to lose. It's not, however, because your muscles turned to fat. Muscles may atrophy or lose their tone, but they won't turn to fat. Muscle is muscle and fat is fat.

Exercise increases appetite

This is true for hard or intense exercise that lasts for 60 minutes or longer. Moderate exercise that is less than 60 minutes, however, will probably reduce your appetite for one to two hours.

Exercise always lowers blood sugar Generally, exercise will lower blood sugar and it's best to prepare for exercise by eating before you start out. If your blood-sugar level is above 250 mg/dl, however, exercise could make it rise even higher.

You can get fit in 10 minutes a week

This and similar claims are common, but untrue. There are no shortcuts to getting fit. Becoming fit takes work and the general rule is 20 minutes of aerobic activity three times a week. Consistency is the key. If you miss a day or two, don't try to compensate by doing double duty--you open yourself up to injury.

No pain, no gain

Many people tend to overdo their exercise programs looking for quick results. Doing so, however, may prove to be your downfall by resulting in injury or sore muscles.

Your best bet is to start any exercise program slowly and gradually increase the workout.

We start people out with 15 minutes of stretching, 30 to 40 minutes of walking or walking/jogging, and end with 10 more minutes of stretching. This gives people a good beginning without the pain or injury.

Electric stimulation

Electric stimulation may help make a muscle contract and tone it slightly, but this technique can't take the place of exercise, and it certainly won't help you lose weight. If you want to decrease body fat, you must do aerobic exercises.

体能是当今的热点话题。走到哪我们都会听到一些关于体能的新鲜话题。但这些都是正确的么？

出汗越多，脂肪燃烧得越多

这个观念鼓舞着希望通过流汗将脂肪流掉的人们做极热运动，穿多层衣服或橡胶，塑料类减肥服装。但，很不幸的是，流掉的是水分。不是脂肪。

脂肪只有在运动中作为一种能量才能消耗，并不出现在运动的初期。刚开始做运动时会消耗碳水化合物和糖类。在从消耗糖类转化到消耗脂肪之前需要至少20分钟左右的温和的有氧运动。（有氧运动指任何有节奏，连续的耗氧并需要运用身体的大量肌肉的运动，如胳膊和腿脚。例如：骑自行车，跳绳，步行，慢跑，有氧舞蹈和游泳。）因此，要想燃烧脂肪，至少要锻炼40分钟。

如果停止锻炼，肌肉会变成脂肪

如果减少运动量还是吃那么多或者更多，之前努力减下的肥肉还会反弹回来。这个，怎么说呢，并不是你的肌肉转化成脂肪。肌肉可能会萎缩或失去弹性，但是不可能变成脂肪。肌肉是肌肉，脂肪是脂肪。

运动增强食欲

对于持续60分钟或更长时间的激烈运动来说，这个是事实。而对于少于60分钟的适度运动来说，却极有可能在1~2个小时内减弱食欲。

通常，运动总是会降低血糖。因此，最好能在开始准备运动之前吃点东西。如果你的血糖浓度在250mg/dl以上，运动只会让血糖浓度升得更高。

每周10分钟让你更健康

这个观点或者相似的其它观点是很常见的，但却是不正确的。健康没有捷径。健康需要锻炼，一般规律是每周三次时长20分钟的有氧运动。持之以衡才是重点。不要试图做双倍的运动弥补你错过一两天的动动－－这只会让你更容易受伤。

不劳无获

许多人由于急于求成而倾向于运动过量，然而，这么做只会造成受伤或肌肉酸疼而加速体质的衰弱。

做任何运动计划最好是慢慢地逐步增加运动量。

我们让人们先做15分钟伸展运动开始，，30~40分钟步行或步行/慢跑，然后以10分钟的整理运动结束。这样能让人有一个没有疼痛和受伤的好的开始。

电激

电激可能会帮助肌肉收缩并保持弹性，但这项技术并不能代替运动。而且肯定不会帮你减肥。如果你想减掉身上的脂肪，你必须做有氧运动。