Core Strengthening A strong core is essential for overall fitness and stability. Planks are one of the most effective exercises for this purpose. They engage not only the abdominal muscles but ...
Wells, John R., Elizabeth A. Raabe, and Gabriel Ellsworth. "Bally Total Fitness (A): The Rise, 1962–2004." Harvard Business School Case 706-450, November 2005 ...
Wells, John R., and Gabriel Ellsworth. "Bally Total Fitness (B): The Fall, 2005–2016." Harvard Business School Supplement 717-422, October 2016. (Revised January 2017.) ...