As the grassroots football season comes to an end, it's possible you're already considering other ways to keep fit and stay active through the summer months.

How about cricket, tennis, running (cross country or track), or even just get the bike out and get your heart rate going that way?

But whichever you choose, one of the things you need be aware of is how the different surfaces are likely to impact on your body.

It's a problem that looks to have caused Andy Murray to retire from the Italian Open this week, after suffering a repeat of the back problem that seems to happen when he plays on hard clay surfaces.

You may remember that Murray was labelled a drama queen by an opponent at the French Open last year, a reference to Murray's constant need for treatment during matches and complaints that his back was causing him pain.

But alternating surfaces is a real problem for anyone in sport and firing barbs at Murray is a little naive and unjust and here's why.

Switching surfaces is known to cause injury. Simple as that.

If you've swapped a grass football pitch for a game of indoor five-a-side, it's very likely you've experienced something similar. Perhaps your hamstrings and calf muscles felt much more stiff and tight the next day?

Spongy running tracks pose a similar problem.

Even if you are supremely fit and running regularly on the road, trying to do the similar distance on a running track would be completely different - at first. And it's your lower back and hamstrings where the problems would surface.

It's often due to the change of impact. The bounce effect of the track means that your lower back is having to work much differently to the thud type impact it's used to when road running.

It's not that either are dangerous, they're just different. And that's the problem for Murray.

The many different surfaces that top tennis players have to perform on mean that they not only need the technique to cope with the change, but also the physical capability to match.

In any sport, on any surface, the powerhouse and most important part of your body is your lower back.

If there is a spine weakness, or it's too stiff and tight, then you can expect problems and injuries as you swap surfaces.

You are particularly at risk if you spend most of your day in a seated position, at work at a desk, or driving.

The pressure on your lower back is at its most when seated so it's important to make sure these muscles are as strong as possible by doing things like balance ball, core and pilates exercises.

And you also need good movement and flexibility there too.

If back movement is reduced, it means that things like hamstring and groin muscles will be getting pulled too tight - meaning you're a likely candidate for injury or to suffer from unnecessary next day aches and pains.

If you're a regular reader of my column, you'll know I'm constantly encouraging the need to vary your training.

Alternating between things like pilates, yoga, fitness classes, bike riding, running and swimming is the best way to keep cardio-fitness high and injury risk low.

Do that, and your body never gets chance to settle onto the comfort zone of one particular surface.