The rocker function serves primarily for training the outer calf muscle (gastrocnemius). It is the calf’s powerhouse and responsible for giving our footprint its kick. The rocker function is also interesting from another perspective, as it accounts for the theory of econcentric loading or “load to explode” – the idea that every muscular contraction needs to be preceded by a stretching motion to achieve maximum force. While the muscle is stretched, it is charged with energy, This energy corresponds to a net gain towards the total force delivered in the contraction phase. It results in a greater total output and therefore improves performance. Using the BlackBoard Training System’s rocker function, you can combine the charging and contraction phases, which is ideal for human physiology and optimizes training results.