Leeds United's magic number dictating Jesse Marsch decisions in Spain and what it means

Head coach Jesse Marsch will routinely turn to his first team sports scientist to enquire as to where Leeds are, and Robinson, peering out from behind a screen, responds with a number.

Like many of Marsch's staff, Robinson has been required to take on extra duties this week to help out with training scenarios, like free-kicks and corners. On Tuesday he was jostling for position in the area as goalkeeping coach Marcos Abad sent in deliveries for him to attack and first team players to defend.

But his main role is to track and monitor the physical exertions of Marsch's squad, to ensure that targets are met but not exceeded. And the number he feeds back to Marsch often appears to signal when or how soon the American should bring training to a halt.

"So we use live GPS monitoring in the training," said Robinson.

"It's quite common practice in sports science and professional football these days. The number that I'm reading out is one called high metabolic load distance. That's a unit of measurement that STATSports have created to measures basically, how much the players are accelerating and decelerating and covering distance at high running speeds.

"It's a quite good indicator of how difficult the session is and what sort of demands we're placing on the players bodies.

"We have figures on the players for what their high metabolic load distance would be in a game and we have a good understanding of what percentage of their match output the figure for today would be, so there's individualization in terms of that but the global target for the session is for everyone."

The numbers Robinson calls out from his tablet are collated and pinged to it by trackers in the GPS vests worn by the players, alongside information from heart-rate monitors.

"The vests have got a tracker that goes into that and we also wear heart rate monitors so you get a good idea of the volume and the intensity of the training, and you also get an idea of the cardio vascular response as well," he said.

"So how much you are actually stressing their aerobic system and making them fitter through that work.

"Red zone is like the time that you spend above a certain percentage of your max heart rate and that's usually set around 85 per cent of your max heart rate. On the hard day's training, you want it to get above 85 per cent and spend a good amount of time in there and that's where you get those training adaptations."

According to Robinson, who has worked on the conditioning and physical preparation of Leeds players for 11 years now, Marsch has a helpful grasp of this kind of data and its usefulness, but the decisions on how hard to work the players are taken collectively.

"Jesse's worked with this sort of high metabolic load distance metric throughout his career so he's got a really good understanding of the training loads that he wants to impart on the players," said Robinson.

"That's been a way that we've been able to manage the training loads for this pre-season period. It's a multidisciplinary approach, so between us in the medical department and the coaching staff, we have a regular meeting and the structure of the week is set and the structure of the days are set as a group, based on what players need, based on the proximity of the next match, based on previous injury, things like that."