Interesting fact.
Heard from Rob Innes years ago that they had a hamstring testing machine. Would test each leg after training early in the week as part of each players wellness report.
Players would self report their level of comfort each time whilst the hamstrings were put through a level of pressure tests whilst laying on a bench.
These days just about everyone uses something called a Nordboard. The data and testing indicators you get can be useful but the pesky things still find a way to go without any warning.
I've told this story before but I was once involved somewhere we we suffered a spate of soft tissue injuries and were desperately searching for something to help explain them. Went through all the usual stuff, training loads, weight and strength data, game gps numbers, how much kicking they were doing at training, in games etc......
Then someone came up with a theory that maybe we should consider the weight of the footy. Calculators came out and Newton's laws on force equalling mass x acceleration were applied and the theory grew some legs. We already knew kicking a footy puts a good load of force through your leg, over 100kgs, hence the need to be careful with how much of it you do.
What we didn't realise until we started weighing footballs is new ones have a fair degree of variation in weight, up tp 40 or 50 grams and as you use them and they get wet or absorb sweat or grippo they grow a bit more, sometimes varying by 200 grams or more, which could vary that force by 50 or 60 kilograms, every kick.
So we started fanatically weighing footballs and dismissing the heavy ones. Naturally the property people weren't thrilled about having to return balls to Sherrin and tell them we didn't want them because they were 29 grams heavier or tripling ball expenditure so they in turn invested in systems to try and remove moisture from the balls to keep them for longer.
Needless to say the injuries stopped, almost certainly for every other reason except the weight of the footy, but there was no going back and I'll bet to this day that club weighs every footy (and they aren't the only ones). That's the sort of levels of madness this stuff takes you to.