Mick McCarthy laughs as he recalls one of his early pre-season memories as a player with Barnsley. "It's a bit of a legendary story this one," the Wolverhampton Wanderers manager says, smiling. "We were doing a road run and we ran so far in Barnsley that a few of us got lost. As we had fallen such a long way behind the others, a small group of us decided to hitch a lift back to the ground. By the time everyone else got back, me and three others were already in the bath."

It is a stunt that a few have tried over the years, although there was no chance of anyone in the Wolves squad repeating the trick during their pre-season training camp in Ireland this week.

The days of gruelling long-distance road runs are a thing of the past because of the growing influence of sports science, while the introduction of state-of-the-art technology, including GPS tracking devices, means that there is no hiding place on the training ground, let alone in the back seat of a passing car.

This week the Guardian spent a day with Wolves in the grounds of the luxurious Carton House Hotel in Maynooth, near Dublin, where the Midlands club have started their preparations for the new season.

The behind-the-scenes access provided a fascinating insight into the way that a Premier League club approaches pre-season training, revealing just how much the landscape has changed, including the sort of attention to detail that would have been unimaginable only a few years ago.

One of the most significant factors driving the shift in emphasis is that it is often a fitness coach, rather than the manager or his assistant, that takes the first couple of weeks of pre-season training. "I almost feel like I'm pinching a living during the first fortnight," Terry Connor, McCarthy's assistant, says as we walk down to the training pitches, where Tony Daley, the former Aston Villa and England winger who is Wolves' fitness and conditioning coach, is setting up the equipment for his second session of the morning.

The Wolves players, who were in the gym between 8.30 and 9.30am lifting leg weights, step on to the scales, which they do before and after every training session to monitor fluid loss. They are then issued with their heart-rate monitors and GPS units, which are linked to a laptop on the side of the training pitch that provides real-time results. It is an incredible tool that is used by the top clubs in Europe and allows coaches to access a broad range of data on every player at the touch of a button.

"GPS is a big thing at the moment, in terms of finding out the intensity players are working at, what distances they are covering and comparing that with their Prozone stats in games," Daley says. "If, for instance, we know that Christophe Berra covers 9km in a game and he only does 250m of that as high-intensity runs, then why are we, as a club, asking him to cover distances much different to that in training? We want to replicate in training what players are doing in matches."

This also helps to explain why the longest run that the Wolves players will do during pre-season will last no longer than three minutes. "Players don't run for 25 minutes at a time, it's stop-start and it's all about recovery," Daley says.

One of the other reasons that players have stopped plodding around for mile after mile, Daley says, is that runs of that nature were designed to shed a few pounds and get players back into shape. The Wolves players, however, are never out of shape.

Daley tells them to take a complete break for a fortnight at the end of the season but for the next four weeks they are expected to train every other day for about 45 minutes. It is easy to see whether or not they have been following the programme because they undergo four different physical tests four times a year, including at the start and end of the season, measuring their speed and agility, fatigue levels after sprinting, leg strength and aerobic capacity. Anyone whose results appear outside their normal range will stand out like a beacon.

Not that there is much chance of that happening. "I think the players are so much more professional now, and you can probably put that down to the foreigners that have come into the game," Karl Henry, the Wolves captain, says. "Before they came over, I think the drinking culture in the older players was something that was quite widespread, and people would come back out of shape, whereas now people come back and are weighing in at the same weight as they were when they left."

Henry has just finished several attempts at the speed and agility test, which requires players to sprint around four cones, laid out in a T-shape, in about nine seconds. Daley shouts out the times, which are all logged, as the players cross the line.

It is quite a contrast from the days when Henry remembers "running myself into the ground" as a youngster at Stoke. "It's still hard now but it's much more specific," he adds. "There's nothing specific about running up a hill or in a forest for a day and killing ourselves."

Having been split into two groups, the remainder of the Wolves players are taking part in games of head-tennis before they swap over to the physical work. The atmosphere is fairly relaxed, although the club's match analyst, James Lovell, who has been given the thankless task of refereeing, could do with some help from Hawk-Eye to prove to George Elokobi that he is not giving all the debatable points to the other team just because McCarthy is on their side. "You're not watching the game," barks Elokobi, much to the amusement of everyone else.

There was a time when McCarthy would have had a whistle around his neck and a stopwatch in his hand during pre-season but those days are long gone. "I've got guys who have gone to university and studied sports science and strength and conditioning," McCarthy says.

"Tony Daley is brilliant and so is Steve Kemp, the physio, and Matt Perry, the doctor. They head that team and I let them run it. And why would I not listen to them? It's like getting a builder in to do your house and then telling him how to do it. It's just not right."

McCarthy smiles when asked about some of the methods of yesteryear. "I remember being given salt tablets and told that would stop me getting cramp. Well, actually, stopping running seven miles in a morning would have stopped me getting cramp.

"It's more structured and scientific now. I've no doubt when I was doing pre-season my managers would have had it all planned what we were going to do: running, weight sessions, press-ups and sit-ups. But it just appeared that we always did it to exhaustion; players being sick. I've never seen players here being sick."

Training finishes at midday, giving the players an hour break before lunch and then a further two hours before they return for the tougher afternoon session.

When they come back they are once again divided into two groups, half of them starting off with Daley. A large square is set out for them to run around with a ball at their feet, dinking it over hurdles and dribbling around cones. By introducing the ball to a physical exercise the players have to maintain their technique while becoming fatigued. They work for four minutes before swapping over, completing the exercise three times in total.

The others are working with Connor, who stations half a dozen of them on the outside of a small grid and tasks them with keeping the ball from the two in the middle. The ball fizzes around, leaving Dave Edwards and Berra chasing shadows, before a few wayward passes prompt Connor to remind the players that, although pre-season has only just got under way, he still expects high standards. "I am not going to start chewing on my first day but I will get ratty," the Wolves assistant says.

All the while Neil Dallaway, who has recently joined the club as a GPS analyst intern, is standing over the laptop on the edge of the pitch, scanning his eyes across the figures that the small units on each player's back are registering with every step that they take. As the data is instant, it means that Daley can run across and take a quick look to check that the session is having the desired effect. "That's just what I was after," he says, after asking to take a look at a few of the players' heart rates.

Daley points out that "sport science doesn't rule the training field" but he also appreciates the value of using the technology to support his work. "It's a great tool," he says, "and the players have bought into it. We produce a rough report after every training session and it says distance covered, what their heart rate was, sprint distances. And, although it's not intended to be a competition, it becomes like that, because you hear players saying: 'I did X amount'. It's really about educating them. Some aren't bothered about it, but others will want to know why their stats are different to someone else's."

Kevin Doyle is one of those. The Irishman wanders over to Dallaway to inquire about his heart rate and how that compares with the other players after the first of three 800m runs that have to be completed in under three minutes, with a three-minute rest in between. It is the last exercise and the hardest part of the day by far. By the time the second run is over, there are a few people bent over, no doubt wishing there was not another 800m to come. "Come on lads, one more," Sylvan Ebanks-Blake says, trying to lift the mood.

Andy Keogh, Elokobi and Henry seem to be the pick of the runners, although there is little to choose between them, which is credit to someone like Jody Craddock, who turns 36 this month and is taking part in his 19th pre-season. "That was quite hard this afternoon," Craddock says after the players have finished their warm-down. "The running with the ball is designed to keep your concentration when you're a bit tired. It wasn't too hard – it's only the second day. We did the 800m and we'd knocked 30 seconds off each run from the day before. But it will get harder."

Not as tough, though, as when he started out with Cambridge United, in 1993. "One of the first few pre-seasons with Cambridge we would go to an army camp for a week. It was like you see in films – a lot of shouting, graft, running with logs on your shoulders, until they break you basically. And here we are now with everyone wearing heart monitors. It's beneficial to the player; they can take you to your limit and then hold you there as long as they want without pushing you over. I think the tendency when you were younger was to do too much too soon, because it wasn't monitored, and then you couldn't walk for a week with sore legs and blisters."

Any of the Wolves players who have aches and pains after the end of their second day of pre-season have the medical staff on hand to offer them a massage. Most, however, are just keen to get back to their rooms and cross off another training session. "Pre-season is the one horrible part of being a footballer, and some of the runs are terrible but look at the facilities here," Henry says, surveying the surroundings. "We are here on a lovely day with nice pitches to train on. There's not much to moan about really."

Training day

Wolves' first week of pre-season training made summer holidays seem a distant memory

7-8am Light breakfast (optional)

8.30-9.30am Players report to gym and are divided into two groups, alternating between doing the jump test (measures leg strength) and a leg-weight session. Players given a protein recovery shake immediately afterwards

9.30-10.30am Breakfast (cereal/fruit/eggs)

11am – noon Stretching. Players divided into two groups, alternating between the T-test (speed/agility) and head-tennis

1pm Lunch (carbohydrate and protein-based)

3.15pm-3.35pm Dynamic stretching session (on the move rather than static)

3.35pm Players divided into two groups, alternating between an endurance session with the ball (dribbling around cones, lifting it over hurdles and running with it at their feet for four minutes) and a keep-ball session, when they are, in effect, recovering from the other exercise. Three times through on each exercise

4.10pm-4.25pm Players have to complete three 800m runs each inside three minutes, with three minutes of rest in between the runs

4.25pm A 10-minute cool down followed by ice baths, massage and rest

6pm Dinner (carbohydrate and protein based) followed by rest for the players

Tests and checks

Heart-rate monitors and GPS

Heart-rate monitors have been used for some time but hi-tech GPS (Global Positioning System) units and the real-time software that come with them are not so common. The instant data that the GPS devices provide allows the coaches at Wolverhampton Wanderers to monitor the physical performance of their players on the training ground while the session is taking place and tailor training to replicate each player's work on a match day

Close-season training

The Wolves players are told to take a complete break from exercise for two weeks at the end of the season, but they are given a programme to follow over the next four weeks that requires them to train for 45 minutes every other day, ensuring that they report back for pre-season in reasonable shape and close to their normal level of fitness

Regular testing

Wolves carry out four tests four times a year – the start and end of pre-season, the end of December (depending on the match schedule) and the end of the season – to measure players' speed/agility, endurance, leg strength and aerobic capacity. The results are logged and the players are expected to stay within a specified range whenever tested

Weighing and body-fat testing

The players are regularly weighed, including before and after each training session during pre-season, when the club monitor fluid loss. Measuring the players' body composition in millimetres gives the club an idea of lean-muscle mass and what percentage of their body is fat. The players are measured in eight areas and, as with the physical testing, need to maintain their target levels