“The Plank” has become a very popular – even trendy – exercise recently. It’s a yoga pose touted for its ability to strengthen deep abdominal muscles, the pelvic floor, and the transverse abdominis, which supports your back. Fitness trainers will often recommend that the pose be held for as long as possible each day, as it can be a powerful tool used to strengthen your core.
However, Stuart McGill, a professor of spine biomechanics at the University of Waterloo says this recommendation is a bad one. Holding the plank for too long can cause back pain, and because it increases pressure in your abdomen, it can also cause blood pressure to rise. For people who already suffer from high blood pressure, or other heart and circulatory problems, sustained holding of plank can be bad for your health.
Rather than holding the plank steadily for 1-5 minutes, Professor McGill recommends holding it for just ten seconds three times in a row. After that, you can take a short break before holding the pose for another ten seconds twice in a row.
While being able to hold plank for more than one minute is a sign that your core is strong, it also means that the plank is no longer giving you much of a challenge. In that case, you can try alternately lifting up one arm or one foot, or doing a side plank instead.
http://www.dailymail.co.uk/health/article-4575458/Why-plank-bad-blood-pressure.html
About the Author: Rebecca Wong has a BA in English Literature from the University of Waterloo and has been working in the herbal business since 2000. She studied at the Ontario College of Traditional Chinese Medicine under respected authorities Paul Des Rosiers and Vu Le, and graduated from the East West School of Planetary Herbology under Michael Tierra. She received training as a yoga teacher at The Branches in Kitchener/Waterloo, and therapeutic yoga teacher training from the School for Somatic Soulwork under Deniz Aydoslu. She now teaches yoga for anxiety, depression and burnout at Rebecca's Restful Yoga Studio in Toronto.