The Most Important Jump For Explosive Starts!
Swimming is a unique sport, few sports require you to explosively jump forward from a completely static and extremely compact position. Learning how to jump from a static position is key to achieving a rapid start off the blocks. Elite Australian swimmers have shown block times of ~0.72s and ~0.77s for males and females respectively during the ‘Track Start’ and 0.57s-0.63s and 0.61s-0.67s during Backstroke starts for males and females respectively.
So, selecting a jumping exercise during training that fits these time constraints makes a whole lot of sense. Two common choices are the Countermovement Jump (CMJ) and the Squat Jump (SJ). A CMJ has a rapid downward movement followed immediately by a jump, while an SJ features a 3-5 second pause in the lowest position before a jump. A CMJ can take anywhere from 500-1,000 milliseconds to complete, whereas an SJ can be completed between 300-430 milliseconds, factoring in the pause makes it much more specific and applicable to swimming starts.
Some things to consider:
Foot stance similar if not identical to squat/trapbar stance.
Jump depth is independent, what feels natural to the athlete.
Exaggerate the pause, 3-5 seconds.
Keep the body rigid and create tension.
Focus on jumping as high as you can.