Kinematic and kinetic tumbling take-off comparisons of a spring-floor and an air floor(TM): a pilot study - Sands, W. A.; Kimmel, W. L.; McNeal, J. R.; Smith, S. L.; Penitente, G.; Murray, S. R.; Sato, K.; Mizuguchi, S.; Stone, M. H. (Science of Gymnastics Journal, 2013)