What happens when you stop exercising?
We all know that exercise promotes a lot of positive health benefits, both physical and mental. We also know that starting a routine and sticking to it is hard. What’s less well-known is what happens to the body when an exercise routine is stopped, and it can make you wonder why you bothered in the first place.
You may think that the difficulty in returning to the gym after a spell away is just down to being out of practice, but it’s actually a symptom of the biological changes that have taken place in the absence of training. io9 recently ran an excellent feature on the physical process, and here are some of its key points.
The first is that, cruelly, the fitter you are, the harsher the effects of reduced exercise will be. “W
The first is that, cruelly, the fitter you are, the harsher the effects of reduced exercise will be. “What applies to an elite athlete after one week might take a sedentary individual one or two months to experience,” explained Andreas Bergdahl, an expert in cardiovascular physiology from Concordia University.
That’s not to say that a lazybones will be in better shape, but the elite athlete will have lost a lot more of their overall fitness, presenting a short sharp shock to athletes entering retirement or forced off the field through long-term injury.
How can this be measured? One of the more clear-cut ways is through examining oxygen uptake, or VO2. This monitors oxygen concentration in the blood going to and from the heart, and shows how efficiently the athlete is performing. It’s generally the first metric to decline. “There are studies indicating a decline of 7-10% of VO2 after 12 days of sudden inactivity, 14-15% after 50 days, and 16-18% after 80 days,” says Bergdahl.
Other areas also decline: muscle structure, power, strength, stamina, coordination – all the things that have been trained for years. What does that translate to in real terms? Well, Harry Pino from the Sports Performance Centre at NYU Langone Medical Centre said that runners are hit especially hard and cites an example of a 20-minute 5k runner losing 10 seconds after a week of inactivity, but only really noticing the decline after two to three weeks. After two months, their 5k time of 20 minutes has reached the 23-minute mark.
“It’s shocking to see what happens to the body,” said Pino. “We start to see lots of changes to muscle, strength, and fat levels – it really deteriorates your structural well-being.”
“Remember, you’re still better off being a washed-up athlete than someone who never exercises – you’ve got less far to fall.”
Interestingly, VO2 levels don’t change significantly with age, although muscle mass is more obviously affected by the ravages of time. The relatively good news here is that muscles don’t deteriorate at the same rate: they’ll decrease after three weeks of detraining, but, nine weeks later, will still keep a “significant amount of bulk strength and endurance”.
Perhaps the most interesting part of the piece concerns weight. Contrary to popular belief, muscle doesn’t turn into fat: “What really happens is that the muscle cells – which are completely different from fat cells – become smaller, because they’re not growing now that you don’t have a demand of power and strength,” explained Pino. Meanwhile, the fat cells have no such qualms. “Instead of looking lean and trim, you start feeling bloated and round.”
What can you take home from this? Don’t stop training if you can avoid it. Rowing machines, stationary bicycles and cross-trainers all offer alternatives that can help stem the decay. And remember, you’re still better off being a washed-up athlete than someone who never exercises – you’ve got less far to fall.