Like other domesticated animals, your guinea pig needs exercise to help keep him strong, and to help keep his weight under control. Unfortunately, your guinea pig may not be getting the exercise that he needs in order to remain in good health.The first problem is typically that the guinea pig does not have ample room in his pen. You could literally fill his pen with hundreds of dollars of toys, but he still won't get proper exercise. What he needs is space. He should have plenty of space to run around. A popular activity among guinea pigs is running as fast as they can around the interior walls of the pen. If there are too many toys or other items in the way, he is prevented from doing this.
Hamsters get plenty of exercise on exercise wheels. Guinea pigs do not use exercise wheels. They have absolutely no interest in them, and the most that they will do with an exercise wheel is to get in it and go to sleep. Guinea pigs also require leaping room, so that they can express their joy by pop corning. When a guinea pig is really happy, he will start running, and leap into the air while running. He may even do a few flips.
While guinea pigs are not jumpers, and many don't climb well, if you provide a climbing space that appeal to them, they will get lots of exercise from climbing. You can stack bricks, forming steps small enough for your guinea pig to easily manage.
Guinea pigs have a hard time getting traction. For this reason, providing running space on slippery floors isn't a good idea. Carpeted areas and rough cement areas seem to be ideal for running space, giving your guinea pig plenty of traction.
Even if your guinea pig has ample space in his pen, it is important to let him out on a regular basis. Note that when he is out, he needs to stay in your sight. Otherwise, you will find chewed cables and other chewed items throughout your home. Watch him closely, and let him get exercise by running and exploring in different areas of your home. This will also go a long way towards keeping him happy as well. It is a good idea to allow your guinea pig at least a half hour of exploration time each day.
Provide your guinea pig with a series of tunnels to play in. These can be constructed from tunnel systems purchased at the pet store, or with plain PVC piping and joints. Provide turns in the tunnel, and also use leveraging to create uphill climbs and downhill runs in the tunnel. Just don't make the inclines and declines so steep that your guinea pig avoids them.
Again, toys, such as those for chewing are important, but do not provide exercise. For exercise, your guinea pig needs running space, and some gentle climbing accessories as well. If you provide these things for your guinea pig, you won't have to worry about him becoming overweight and unhealthy.