Cricket: Body science drives Black Caps quicks

Years of scientific research will lie hidden behind every Black Caps ball sent hurtling down the pitch at Christchurch's Hagley Oval tomorrow.

With Trent Boult, Tim Southee and Adam Milne, the Black Caps enter the World Cup with one of the most formidable array of pace bowlers this country has fielded.

It hasn't been all coincidental - our firepower has been boosted by a groundswell of research driven by AUT University's Sports Performance Research Institute New Zealand (SPRINZ) and Cricket New Zealand.

This effort, spurred by fast-bowling winter camps that began five years ago, has unlocked new insights in biomechanics, produced new research and triggered a major shift in the way bowlers are trained and conditioned.

When investigating the dynamics, the researchers picked apart three specific areas - run-up, pre-delivery stride and delivery stride.

SPRINZ co-director Professor John Cronin said run-up speed - and specifically the speed in the final five metres - had been shown to affect the ball speed of the fast bowler.

This meant the ball velocity could be directly influenced by improving technique, power and speed to first increase the maximum running speed of the bowler, and then transfer that speed into their delivery.

"Also, deceleration from running during the delivery stride requires large amounts of eccentric or braking strength through the legs, and is often overlooked."

Researchers had also discovered the angle of the bowler's front leg and "braking forces" on the delivery stride were major predictors of ball speed.

"The large ground reaction forces that the fast bowler produces through the delivery stride are undoubtedly a major contributor to the high injury rates," Professor Cronin said.

"To withstand these forces, a large amount of leg strength - and specifically eccentric leg strength - is needed to help with the absorption of those forces."

For a fast bowler, the forces could be up to 12 times their body weight, said Cricket New Zealand's general manager of high performance, Bryan Stronach.

"So if you've got a 100kg guy who absorbs 10 times his body weight - there's 1000kg every time he bowls the ball.

"You've got to be seriously strong to handle that."

The realisation that "big, fast and strong" could lead to more weight, and thus more injuries, caused a shift away from rugby-like conditioning, he said.

"We realised that these guys needed to be very strong through the lower body and still strong through the upper body, but with no excess fat mass or muscle mass," Mr Stronach said. "If you look at Trent Boult, Tim Southee or Adam Milne, they're not really big guys - they've got strong, solid legs, but they are actually quite wiry and lean through their upper bodies."

As fast bowlers could cover 22 to 28km in a day, they also needed to be trained to endure such distances - yet they were are also expected to run like the wind when attacking the crease.

Compared with other positions, fast bowlers covered 20 to 80 per cent greater distance and sprinted up to eight times more than other positions - all the while being given at least 35 per cent less recovery time between high-intensity efforts.

This all had to be considered in their conditioning regime, Mr Stronach said.

"I think the research and what we know around this area is still very limited - we've still got a long way to go to nail it, but I do think we are further down the track in getting it right."

Whether there was a physical limit to speed - something South African gun Dale Steyn has been edging closer toward - remained to be seen.