You will need a run so your Guinea Pigs can go outside to stretch their legs and graze on some grass. They will need some kind of shelter in their run to shade them from the sun and to keep them warm and snug in the winter. Although we would not recommend having them outside in the winter. Instead, buy a play pen and set it up in your front room and lay down some towels to protect your carpets. Cut some grass and give it to them. We prefer ours to run about in a safe area inside as they are always safe and that way they get their exercise even in our typical British weather. It is also great to have runs outside, for when it's lovely and warm. Remember, you must supervise them.
Piggies can get exercise in their cages if you give them enough room to explore. Change their set up daily to give them new things to do. Just shuffling a few toys around can make it seem like a whole new area.
DO NOT USE THE FOLLOWING:
Large Exercise Balls
These are very bad for Guinea Pigs as they can and will cause crippling injuries to their back, feet, and toes. The ball may be physically large enough to hold a Guinea Pig but it is still not safe. Guinea Pigs are not as flexible as Hamsters and other small rodents - their spines simply do not bend that way. Some packaging may say they are ok for Guinea Pigs but it is incorrect.
Exercise Wheels
These are also very bad for Guinea Pigs as they can and will cause crippling injuries to their back, feet, and toes.
Anything that has small parts shouldn't be used either, as small parts can be a choking hazard.
Please understand - these balls and wheels are potentially lethal - your Piggy could break its back! There are so many cheaper alternatives that your Piggy will love!