Many people feel that some types of yoga don't provide enough of a cardiovascular workout. According to the American Heart Association, aerobic activities, such as brisk walking, running, swimming, bicycling, roller skating, and jumping rope, done three or four times a week for 30 to 60 minutes, are best for improving the fitness of the heart and lungs.
And as far as hindering a yoga practice, activities like running can create tightness in the hamstrings. Some yogis feel that after running for 20 minutes, both the hamstrings and hips should be stretched for 20 minutes. Shiva Rea, yoga teacher and former Yoga Journal "For Beginners" columnist, says, "One of the gifts of yoga practice is refining your observation skills and learning to listen to the language of your body. Check in to your body as well as your constitution for signals of any imbalance. This will help you determine if some types of sports, cross-training, or any routine, from sleeping habits to diet, have a positive or regressive affect on your practice.
"If you feel stuck in the same forward bends, despite regular practice and intelligent instruction, then perhaps you are seeing the effects of other activities working against some of the yoga asanas and by extension your evolution in the practice," says Rea.
Her advice: Try to alter your practice to develop strength rather than automatically turning to weight lifting, which can develop tightness in some key places such as the shoulders and upper back.
Consider adding more arm balances into your routine, for instance. Chaturanga, anyone?