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Why well-trained runners lose fitness the quickest

Answering all of your I-took-a-break-related running questions

Woman runner tired

Even elite athletes find it difficult to stick to a training plan year-round. In almost every training plan is a scheduled break of two to three weeks to reset. In the grand scheme of an entire year, three weeks might seem like nothing, but it turns out that in that time, especially in the case of highly trained runners, fitness can deteriorate quickly. Here’s a look at how that happens.

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How trained were you in the first place?

In a literature review that came out in 2012, researchers aimed to answer questions about how quickly active people detrained. They found that how much you trained before a break had a huge impact on how quickly it went away. For example, when it came to blood-lactate threshold, highly trained runners lost about 50 per cent of their fitness in one week. However, when it came to relatively sedentary people, their threshold didn’t change when they followed six weeks of activity with three weeks of inactivity. 

Blood-lactate threshold refers to the intensity of exercise at which lactate begins to accumulate in the blood at a faster rate than it can be removed. This is a fancy way of describing the sensation of your legs becoming heavy and tired. While these findings may seem contradictory, it turns out that people who train a lot or train habitually see decreases in their fitness faster than people who recently started exercising. Fitness gains can be lost in as little as two weeks for those who train regularly, but it will take longer in those who are new to it. 

If you’ve taken a month off

As a runner, if you train habitually and have taken a month off, the research suggests that you won’t see much of a change in your sub-maximal efforts (easy runs), but you will see as much as a 25 per cent decrease in capacity for bigger efforts, like workouts. Those who recently took up activity didn’t see nearly as much difference.

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If you’ve taken over a month off

From the above results, you might be wondering why you would even bother working out consistently in the first place. If people can work out for six weeks and then take a month off and barely lose any of their gains – why have you been running consistently for a year? The long-term break is why

In athletes who were well trained, their V02 max declines quickly but then stabilizes. In newly trained athletes, their gains are completely lost after a long break. Basically, for those who’ve trained consistently, their initial drop-off is steep, but a basic level of fitness will remain. For those new to activity, they’ll hold on to their level of fitness for longer, but after about four weeks, they’ll lose it entirely. 

Strength training holds for longer

While runners will lose much of their endurance for four weeks, their strength training gains will stick around for longer. Researchers found that even after 12 weeks of inactivity, strength training capability only reduced by seven to 12 per cent in well-trained athletes, and there wasn’t much of a decline at all in those who were newly trained. 

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While the detraining effect happens quickly in those who run a lot, you’ll maintain your basic fitness. Even though the stats are a little discouraging, the best in the world still take an annual break and purposely lose some fitness – taking time off and detraining is actually key to making long-term gains. And as the research shows, if your break is only a few weeks long, the return to your previous fitness shouldn’t take that long, either. 

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