Why am I too tired to workout?

You’ve had plenty of rest, eaten lunch and popped a vitamin but when you hit the treadmill, your legs feel like lead. Lack of sleep isn’t the only reason you might not have energy to burn for a workout. Read on for possible other culprits.

I feel sapped.
Reason: You may be coming down with something. “Higher body temperatures kill microbes that make you sick but may leave you lacking in energy,” says Robert Kenefick, Ph.D., associate professor of exercise science at the University of New Hampshire in Durham. So rest a fever but if it’s a head cold, keep moving to release antihistamines into your bloodstream and stimulate your lymphatic system. You may actually feel better once you get moving.

I feel sleepy.
Reason: Caffeine withdrawal. Did you skip your morning jolt of java? If you’ve had plenty of shuteye, this could be the answer. Subjects in a Journal of Strength and Conditioning study who sipped a moderate amount of caffeine before completing two, vigorous 30-minute treadmill runs had a mental and physical edge compared with those who didn’t. If you’ve sworn off caffeine, try eating half a high carb snack 20 minutes before working out to give you a boost.

I feel sluggish.
Reason: You could be dehydrated. Even if you’re slightly parched you’ll fatigued faster so be sure to whet your whistle every 20 minutes or so during your workout even if you’re not thirsty and even if it’s too cold to sweat. A recent study at the University of New Hampshire found that when people exercised in the cold dehydrated more easily and rated themselves as less thirsty.

I’m just too lazy!
Reason: Maybe it isn’t lack of motivation. Your timing may just be off. Some research has found that most people feel better doing moderately paced cardio in the A.M. when the body is slightly cooler, and stronger when they hit the weights or do high intensity interval training in the late afternoon when body temperature and muscle strength are at their zenith.

All I want to do is bale.
Reason: Paradoxically, maybe you’re not pushing yourself hard enough. It’s long been thought that muscles give out due to an excess build up of a substance known as lactic acid. But a surprising study published in a recent issue of the journal, Science speculates that lactic acid acts as a natural performance enhancing drug to stave off fatigue. Toss in a short sprint when your muscles feel exhausted and you just might get a second wind.