By measuring hormone and other chemical levels before, during and after tough workouts, trainers can precisely tailor an athlete’s regimen.

Scientists at HortResearch in New Zealand are developing a non-invasive and painless method of doing that. Some trainers are already using Hort’s technology by measuring testosterone, cortisol and creatin kinase.

The ultimate goal is to create a portable, non-invasive, ultrasound testing device that can test athletes in real time.