The current study aimed to investigate the effect of ankle restriction on the coordination of vertical jumping and discuss the influence of energy transfer through m. gastrocnemius on the multijoint movement. Eight participants performed two types of vertical jumps: a normal squat jump, and a squat jump with restricted ankle joint movement. Mechanical outputs were calculated using an inverse dynamics analysis. Custom-made shoes were used to restrict plantar flexion, resulting in significantly (P < .001) reduced maximum power and work at the ankle joint to below 2% and 3%, while maintaining natural range of motion at the hip and knee. Based on the comparison between the two types of jumps, we determined that the ankle restriction increased (P < .001) the power (827 ± 346 W vs. 1276 ± 326 W) and work (92 ± 34 J vs. 144 ± 36 J) at the knee joint. A large part of the enhanced output at the knee is assumed to be due to ankle restriction, which results in the nullification of energy transport via m. gastrocnemius; that is, reduced contribution of the energy transfer with ankle restriction appeared as augmentation at the knee joint.
Hiroshi Arakawa (Corresponding Author) is with the Department of Sports Science, Japan Institute of Sports Sciences, Kita, Tokyo, Japan. Akinori Nagano is with the Department of Computational Science, Graduate School of System Informatics, Kobe University, Kobe, Hyogo, Japan. Dean C. Hay is with the School of Physical and Health Education, Schulich School of Education, Nipissing University, North Bay, ON, Canada. Hiroaki Kanehisa is with the National Institute of Fitness and Sports in Kanoya, Kanoya, Kagoshima, Japan.