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Running is excellent exercise. Before you start running, you should warm up first, using slow movement that makes all your muscles work. But be careful! If you stretch when your muscles are cold, you might do yourself an injury. Always wear comfortable clothing and make sure your trainers are in good shape. If you wear shoes that give good support to your whole foot, you will put less pressure on your knees. You should start exercising slowly, at a pace you can keep up for about 15-20 minutes. Try to exercise on soft ground as this will protect your knees and hips from too much stress.
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You should start exercising slowly, at a pace you can keep up _____________________.
for about 10-15 minutes
for about 5-10 minutes
for about 25-30 minutes
for about 15-20 minutes.