Taking urine and saliva samples - "because rugby players spill enough blood" - before and after a game, and then a few days later, they could measure the levels of stress and trauma players' bodies went through and their recovery time.
The trauma levels showed damage in the "ranges expected from serious trauma", the researchers said, likening it to a car crash. However, some players also healed "remarkably quickly".
The tests were honed to four "gold standards" of easily measurable trauma: muscle damage, inflammation, immune resistance and mental stress.
"The idea was to give coaches an ability to judge how banged up or stressed or damaged individual players are. It allows them to get a measure of how each individual responds to the type of rugby games they're involved in," Dr Gieseg said. "It's pretty obvious when someone breaks a leg or tears a hamstring, but there's a lot of small damage and micro damage that doesn't show up until much later."
The team was also interested in using the testing in a clinical setting to monitor a patient during an operation.
"These measures theoretically should be able to tell the surgeon how the patient handles the surgery."
It was hoped the New Zealand Rugby Union would take it on board.
Mr Gill, who assisted with some of the research, said the results were interesting, but not yet at a stage where the tests could be applicable on the field.
"I think if Canterbury University continue to develop the procedure and their understanding of the results, it could one day have great application," he said. "At the moment, it's not something that in the All Blacks we'll be pursuing vigorously in the immediate future, but we're definitely interested in watching closely the development."
While he believed players' bodies "adapt to a degree" to the collisions, he said the aim was to prevent injuries and keep players healthy.
How they did it
The researchers:
• Tested 44 samples per ITM Cup game for two years.
• Used urine and saliva samples instead of blood, for quick and non-invasive testing.
• Looked at four elements to measure the level of trauma a player was experiencing: neopterin, myoglobin, cortisol, and immunoglobulin G (IgG).