Excessive training may result in negative adaptations with respect to NCV, reflex responses and proprioception….- Dr. Angus Ross
Timing the next sprint session is very similar to the sweet spot in baseball. The timing and location must be near perfect to get an advantage. Without getting into harmonics and nodes and anti nodes, the reality is the type and intensity/volume of work between the sprint sessions is the art of coaching as we all know rest between sprinting is necessary. Rest between sprint sessions will be a couple of days, but the choice between 2-4 or more is highly dependent on the work done between the days. Often GSBB options are popular as they represent place holders so athletes don’t become stale or flat, very similar to symptoms of overreaching. Tempo running and other means will work obviously, but this is where I think HRV has it’s place, seeing the effect over time of what is working more precisely to see if you can hit the sweet spot as much as you can.