You might have been working out diligently since making last year’s resolution to get in shape. But what happens when you succumb to the inevitable under-activity and overindulgence of the festive season? Will hours spent popping chocolates in front of the TV and skipping the gym mean the past 12 months’ effort will count for nothing as your figure and fitness go to pot? Not necessarily, say leading exercise scientists. In fact, a break from the gym might be just what your body needs.

“Rest and recovery are often overlooked, but are as important as exercise itself,” says John Brewer, professor of sport at the University of Bedfordshire. “Even elite athletes have one easy day a week to allow their bodies to recover from the stresses of training and to encourage the positive physiological changes, such as muscle growth, that are induced by hard workouts.”

Without enough rest, Brewer says, a tough exercise regime is doomed. “You may improve in the short term, but each body part generally needs 24 hours to recover from hard exercise. If you have been lifting weights with your arms, for instance, it will take a full day for the tiny tears in muscle fibres to be repaired.” He says that most fitness injuries stem from a lack of rest. “Taking time out to let your body recover could save you weeks out through injury in the long run.”

If the run-up to Christmas has been stressful at work and busy at home with workouts squeezed in on top, then time away from running and cycling will almost certainly be beneficial. A few days’ rest will help the body to replenish its stores of glycogen — the fuel used for exercise — top up fluid levels and allow muscles to regenerate. It will also give you the chance to catch up on one of the most neglected aspects of a fitness schedule — sleep. “Getting enough sleep underpins the body’s restorative processes after long periods of working out,” says Greg Whyte, professor of sport and exercise science at Liverpool John Moores University. “A cumulative lack of sleep means your muscles don’t get time to adapt positively to the exercise they have done so that you will hit a plateau eventually.”

A recent study at Stanford University’s sleep disorders clinic analysed the sleep/wake patterns of five fit females over three weeks and asked them to perform a series of tests that included sprinting, tennis serves and other drills. On average the women were getting from six to eight hours of sleep a night, which, considering their active lifestyles, meant they could be in sleep-debt, the sports scientists believed. Sure enough, when the subjects were asked to sleep for 10 hours a night, their performance in the drills improved significantly and they were able to run faster, hit tennis balls more accurately and exhibited greater arm strength. If your lifestyle doesn’t allow you to catch up with sleep every night, then occasional workout breaks are essential to allow your body to overcome general fatigue.

Not that any of this is a green light to put your feet up and knock back chocolates and mince pies for the next month —- there is truth in the adage that you must “use it or lose it” when it comes to exercise. What scientists call a “detraining effect” can show within days, and most experts recommend taking no more than three days of complete time-out. “People should remember that beyond a certain point ‘rest and recovery’ doesn’t stand for being lazy or doing nothing,” Whyte says. “The rate of fitness reversal varies. Your aerobic capacity begins to fall within three or four days of stopping exercise, but muscle strength can be maintained for several weeks even if you do very little.” What experts advise over the Christmas period is “active rest” — such as walking, gentle swimming or cycling — for up to three weeks to keep things ticking over. “This is particularly important if you are consuming more calories and cutting back on your exercise,” Brewer says. “Weight gain will compound detraining so you need to offset that as much as you can.”

It’s not just your body that will reap the benefits of easing back. Dr David Carless, a researcher in sport psychology at Leeds Metropolitan University, says that time away from the monotony of the gym or your usual fitness training sessions “provides an opportunity to recharge mentally”. Recovery periods are “a necessity for top athletes and other people who exercise a lot since it allows them to put their training back into perspective”.

A rest can also prevent you from getting into a workout rut. A study at the University of Florida found that doing the same form of exercise over several months greatly increased your chances of giving up altogether. Not what you need with January around the corner.

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