The effects of de-training

You have just mortgaged your house to join the local health club. Your aim is to lose a few pounds after over indulging at Christmas. The target is to fit in to last year’s summer beachwear before the holiday season. But once summer is here will you continue exercise? Or will you lapse until next January?

Many people start exercising following Christmas in preparation for the summer sun. Very few people, less than 50%, continue exercising throughout the whole year. So what happens to people when they stop exercising? Everyone knows the benefits from starting exercise but detraining is an area of exercise science very few people think about. Detraining affects the body in many ways. The obvious and initial adaptations effect fitness levels. The rate your fitness deteriorates depends very much on your condition before detraining. Fitness levels, universally measured by V02 max, will eventually return to sedentary levels. This will cause breathlessness with slight exertion (e.g. climbing stairs). Highly trained individuals suffer a more rapid decrease in V02 max in the initial stages of detraining; although some a level of fitness is retained. Those people who have low to moderate fitness levels initially incur slower decreases in fitness levels over the first few weeks but V02 max scores decrease to untrained levels in additional weeks.

General health is also seen to deteriorate after ceasing exercise. The heart typically becomes smaller as the muscle wall atrophies. This occurs as the heart muscle without overload or sufficient usage reduces its size to become more efficient for the work it has to carry out. The reduced size of the heart results in decreasing stroke volume, the amount of blood pumped with each heartbeat. As much as a 10% decrease in stroke volume during the first two weeks following training cessation can occur. The decrease in stroke volume causes increases in resting heart rates – the heart has to pump more often due to the decrease in amount of blood transported per beat. During any activity the heart rate will be elevated due to the heart having to work harder when physical activity is undertaken again. As much as 10 beats per minute can be added to maximal heart rates in de-conditioned athletes, thus putting a lot of strain on the organ. The bodies other muscles will also decrease in size rapidly. This decrease in Lean Body Mass will directly affect the bodies Basal Metabolic Rate (BMR), i.e. the amount of fuel (calories) the body utilises at rest. Without decreasing your food intake in line with the BMR the result is often increase in body fat stores.

For serious athletes, such as runners, performance can be affected by as much as 25% over the first 3 weeks of de-training. For those who take up exercise again following a period of detraining this can result in a lot of pain and stiffness, especially if you try to start where you left off. It is important to re-start exercise slowly and progress gradually back to previous levels

Generally, detraining will result in almost all your recent acquired fitness benefits being lost after just one or two months. As age and gravity start taking effect, you will find starting exercise again harder. Typically you will be in a worse position than you were the previous year. Goals to lose weight will become more difficult to attain as BMR is affected considerably by detraining. Rates of resting metabolism also decrease with age, making it harder to shift the Christmas binge, especially following a break in exercise.

If you are planning or experience a period of detraining due to holidays, illness or just through sheer laziness it is advisable to participate in a different or less taxing exercise on your return. This can reduce the detraining effect considerably. Ask you fitness consultant or personal trainer to design a maintenance programme for you during the summer months or when you know you would much rather be strutting your stuff on the beach rather than sweating it out in the gym.
Remember that it is a complete break from exercise and physical activity for more than 2-3 weeks that tends to be most detrimental. A break from your regular workout for this duration will require you to exercise caution when you return to class or the gym. You could end up missing more exercise through injury. Take care and keep exercising!
Mark Mayes, BSc


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