The players have been away on their holidays and have maybe come back carrying a few pounds. Meanwhile, some players will have departed and new players will have been signed. The manager's job, during the pre season period, therefore is to ensure that all his players return to peak fitness and that they come together as a unified and coherent team. Teams that have a poor pre season often start the season poorly and then find themselves having to play catch-up.
Pre season training typically has three main components. These are fitness training, ball work on the training field, and "friendly" matches against other professional or amateur teams.
Fitness training:
Modern football is very physically demanding and players must be in peak conditioning if they are to excel. Some players are natural athletes and may only require minimal work to get back up to the required level. However, there will always be players for whom fitness is more of a struggle and it's importance that the club's coaches work them hard in pre season so that they are ready to go from day one of the new season.
Fitness training is usually made up of a number of component parts. There are the cross country runs that most players hate, which are about getting a lot of mileage and burning off any excess weight. Prizes are often offered as an encouragement. Then there is sprint work, focusing upon pace rather than endurance. Players will be required to complete lots of short sprints and will be timed and their results measured against their previous bests. The final part of fitness training then is gym work, where players will do weights to build up and hone their bodies. Whilst weight training isn't as important in football as it is in rugby, it is still important as superior upper body strength may give a player an edge against opponents in vital on-field challenges.
Ball work:
Whilst fitness is essential, football is a sport where matches are won or lost depending on players' ability to control a football. Therefore, it's vital that the coaches focus as much attention on technical skills as they do on fitness training. Typically, the start of pre season has more of a focus on fitness but then more and more ball work training will be introduced. Drills will be set up to test players close control and bounce matches played where players are only allowed one touch, to sharpen their play. Work will also be done on set pieces and defenders and attackers will be split out and pitted against each other to sharpen both defensive and attacking skills.
Players usually hate the fitness training, especially the bits that involve long distance running or the muscle-burning sprint drills. The ability to switch to some training that involves what they love most, kicking a ball around, therefore is also good for morale and reminds them why they are putting their body through hell and depriving themselves of unhealthy food.
Friendly matches:
There's only so much work that can be done of the training ground and it's important that players get some real match practice before the season kicks off in earnest. For this reason, clubs arrange a series of pre season friendlies. Sometimes they will combine this with a foreign trip that can also be good as a bonding exercise, with players spending time together on the road and in hotels rather than returning to their homes every evening.
These friendly matches are called "friendlies" because there are no points at stake but they can sometimes still be quite feisty. They also often offer an opportunity for smaller teams to take the scalp of a big team and this, plus the presence of a paying crowd, puts pressure on the players to perform, which is just what their coaches want.
If training has gone well during pre season, then this should mean that the players go into the first game of the new season high on confidence. This confidence will be based on knowing that they have thoroughly been put through their paces and are therefore in peak shape. And it will also be based on knowing that they've spent enough time working on skills and playing friendly matches so that their skills have been nicely sharpened and they've had a chance to play together and knit as a successful unit.