Hi Tom, fully understand the question and it is something that I am constantly working on with my players, since the program is a 3 week progression, using a linear progression, I want to develop a little power endurance in the first week hence the 10’s but as you say it is all relative, I have played around with using different heights based on a maximum effort jump height and percentages, as you said your max being around 101 cms and 10’s being around 60 – 70% of 1RM I would say that a box height of 60- 70 cms would be about right for this week, then increase the height each week for 3 weeks, but if you are more advanced you may want to try a more reactive jump and go down and up as quickly as you can for the reps then a lower box height will be needed, there is no problem in having 2 or 3 boxes set up and as you feel the reactivity decreasing drop to a shorter box, ideally we would all have force platforms, check out the Performance Force Platform at http://www.fittech.com.au and the Ballistic Measuring Systems software and products at http://www.innervations.com and then as we detect an increase in ground dwell time above a threshhold level say 300 miliseconds then we would adjust the box height till then we will just have to have a keen look at what players are doing and adjust subjectively as we go, cheers, ash