Let's keep it simple. They're accelerometers so they only measure g-force. If we go through this step by step I think it is fairly clear.
T=0 jumper jumps up (meaning he pulls his legs up and coils his legs and then pushes down as hard as he can. Any g-force in this ? no, or nothing worth considering. T=200mS : stick hits the ground and compresses to the maximum compression g-force Definately maximum g-force we will ever measure (or close to it , because jumper is fresh and not tired out yet. This g-force will dimish as he tires. T= 400mS stick and jumper are moving up but going against gravity . He is not weightless (yet) so I think it is safe to say he is not in a zero-g state, so yes there is some g's but very small amplitute compared to T=200mS. . T=600mS Jumper is at apex. z-g's T=800mS Jumper starts coming down, gradually of course so very little g's but more than T=600mS and very small compared to T=200mS T= 1000mS stick hits the ground (END OF CYCLE) maximum g's That's pretty much it. There is only one place that is easily measurable , but as I stated before, this impact will have duration so at what point do you no longer care about the data ? (I said before at 75% of the very first measurement collected)