Hockey-Dutch women's coach sticks with heart-rate monitors to build a powerhouse

PARIS : The Netherlands' top women hockey players can appear unstoppable at times as they sprint up and down the pitch with apparent ease, not showing the kind of fatigue other teams do in the heat and humidity.

But their secret is actually hidden in plain sight, strapped across the chest or on the outside of the arm, as they use a half century-old technology to better monitor fitness and fatigue.

Through a combination of biometric data from both heart rate monitors and GPS trackers to get readings on effort levels, the Netherlands coaches can build specific exercise and recovery regimes on a player-by-player basis.

"It's important because you read your cumulative fatigue, and if your heart rate is coming down in your aerobic zone and you go back, that's good," the Netherlands women's coach Paul van Ass said.

"But if it's not coming down anymore in your aerobic zone, then you get cumulative fatigue. We try to prevent that. We train to make zones longer and longer and lower and lower."

Van Ass said he first implemented the heart rate approach to training when he coached the Netherlands men's side on their way to the London Olympics, where the team won silver after a disappointing blowout loss in the bronze medal match in 2008.

"It is mostly for determining training. At game time, we look at the real figures. How is a match for your body? And can we adjust or do we have to adjust our training methods or intensity? That's what we do."

If an athlete is having a hard time adjusting or lowering their heart rate back into either the aerobic or recovery zone, it often means that fatigue has accumulated to a point that rest and recovery should be prioritized.

"Nowadays, you have this GPS system. It's just how many meters you run, and