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.

體能是當今的熱點話題。走到哪我們都會聽到一些關于體能的新鮮話題。但這些都是正確的么？

出汗越多，脂肪燃燒得越多

這個觀念鼓舞著希望通過流汗將脂肪流掉的人們做極熱運動，穿多層衣服或橡膠，塑料類減肥服裝。但，很不幸的是，流掉的是水分。不是脂肪。

脂肪只有在運動中作為一種能量才能消耗，并不出現在運動的初期。剛開始做運動時會消耗碳水化合物和糖類。在從消耗糖類轉化到消耗脂肪之前需要至少20分鐘左右的溫和的有氧運動。（有氧運動指任何有節奏，連續的耗氧并需要運用身體的大量肌肉的運動，如胳膊和腿腳。例如：騎自行車，跳繩，步行，慢跑，有氧舞蹈和游泳。）因此，要想燃燒脂肪，至少要鍛煉40分鐘。

如果停止鍛煉，肌肉會變成脂肪

如果減少運動量還是吃那么多或者更多，之前努力減下的肥肉還會反彈回來。這個，怎么說呢，并不是你的肌肉轉化成脂肪。肌肉可能會萎縮或失去彈性，但是不可能變成脂肪。肌肉是肌肉，脂肪是脂肪。

運動增強食欲

對于持續60分鐘或更長時間的激烈運動來說，這個是事實。而對于少于60分鐘的適度運動來說，卻極有可能在1~2個小時內減弱食欲。

通常，運動總是會降低血糖。因此，最好能在開始準備運動之前吃點東西。如果你的血糖濃度在250mg/dl以上，運動只會讓血糖濃度升得更高。

每周10分鐘讓你更健康

這個觀點或者相似的其它觀點是很常見的，但卻是不正確的。健康沒有捷徑。健康需要鍛煉，一般規律是每周三次時長20分鐘的有氧運動。持之以衡才是重點。不要試圖做雙倍的運動彌補你錯過一兩天的動動－－這只會讓你更容易受傷。

不勞無獲

許多人由于急于求成而傾向于運動過量，然而，這么做只會造成受傷或肌肉酸疼而加速體質的衰弱。

做任何運動計劃最好是慢慢地逐步增加運動量。

我們讓人們先做15分鐘伸展運動開始，，30~40分鐘步行或步行/慢跑，然后以10分鐘的整理運動結束。這樣能讓人有一個沒有疼痛和受傷的好的開始。

電激

電激可能會幫助肌肉收縮并保持彈性，但這項技術并不能代替運動。而且肯定不會幫你減肥。如果你想減掉身上的脂肪，你必須做有氧運動。