Before you begin exercising or lifting any weights at all, it's important to take a few minutes to warm up your muscles. Doing some light exercises actually warms up your muscles and makes them more flexible. This way, you're less likely to injure yourself during a workout.
Some warm-ups include exercise bike riding, walking, jogging, or even basic calisthenics. Don't start at the pace you hope to keep during your workout; start slowly, building up momentum and energy as you go. Set a stopping time and then move on with the rest of your workout.
When you begin lifting weights, start with lower poundage to warm up those muscles. Then you can add more weight and start lifting. This way, you won't be as apt to strain a tendon or muscle-group--your muscles will be more limber and ready to handle the strain of a more exertive workout.
While you're lifting weights or doing any sort of exercise, you need to breathe. People have the oddest habit of holding their breath during hard physical exertion or times of discomfort/pain. When you exercise, if you hold your breath, you can actually raise your blood pressure and put a larger strain on your heart and blood vessels.
Breathing sounds simple enough, but in order to make it intentional during a workout, breathe in through your nose, taking a long, deep breath. Then exhale through your mouth. Don't reverse it--you'll end up hyperventilating if you do it wrong or too quickly. Inhale on the 'lift' of an exercise, and exhale on the 'release' of the same.
Some gyms will have step exercises or jogging boards in between the weight machines to help you keep your heart rate up during your workout. This lets you rest your muscles a little between each machine, as well as keeping your heart rate at an optimum level. You don't want to lose the benefits of your exertion between stations at the gym--that defeats the purpose!
After you've completed your strength-training workout, you want to allow yourself four or five minutes of light aerobic exercise to relax your body and give you a chance to breathe easier. Just walk around at a normal pace, then stretch lightly. You'll be amazed at your flexibility and the ability you have to extend arms and legs further than before! Before you think about exercising or doing weight training 6 or 7 days in a row, consider this. When you do weight training to bulk up, your muscles are strained. In order for them to become stronger and larger, they need some time to repair themselves. So let your muscles rest a day in between workouts. Do some walking or aerobics instead on those days and you'll maximize your workout!
About the Author
Kirsten Hawkins is a nutrition and health expert from Nashville, TN. Visit http://www.popular-diets.com/ for more great nutrition, well-being, and vitamin tips as well as reviews and comments on popular diets.

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