What about the weight he’s using? I’ve read no more than 10% bodyweight. Assuming he doesn’t weigh 500lbs., he’s using more. In offseason/early GPP, would it be OK to use the heavier weight (20% bodyweight) for short (10-20m) runs? What about volume and frequency during GPP or off season?
10m runs are really pointless–too short to really be productive and nothing to gain except for “maybe” some technique work initially. I would only use them if the athlete is injured, an absolute beginner, extremely large (circa 300lbs or more), or for very brief durations for initial technique training from blocks or 3pt (for testing). They could very well be counter productive IMO because of being too short and having to cut off the sprint stride to an unnatural degree.
RE: sled weight
I don’t think weight is necessarily a good indicator because it depends on the friction created with the surface/sled combination. Sometimes you don’t need much weight at all and other times you could load it up and it might not have much resistance after the first couple of steps. I have seen substantially big differences in friction differences between different sleds, while other surfaces tend to be more consistent as long as you aren’t on bumpy grass or something of that nature.