How Quickly Do You Lose Running Fitness?

Any runner with big goals—whether it’s finishing a first 5K or qualifying for the Boston Marathon—can get worried at the prospect of taking time off from running.

But sometimes it’s inevitable: You get the flu, have a really busy week at work, take a vacation with the family, or experience a running injury. No matter the reason for taking some time away from running, the best thing you can do is get back to your normal training volume as quickly and safely as possible.

Even though that’s usually the best intention, it doesn’t always happen. So how soon do you actually lose the fitness you’ve worked so hard to gain when you take time off?

More: 7 Tips for Taking Time Off

First, it’s important to understand there are two “types” of fitness: your aerobic fitness—in other words, your endurance—and your orthopedic or structural fitness—the ability of your muscles, bones, tendons and ligaments to withstand the impact of running.

Both are important, but both lose fitness at different rates.

How Quickly You Lose Aerobic Fitness

Thankfully, it takes a little while to lose your hard-earned endurance. For most runners, it takes about seven to 14 days for your aerobic fitness to start declining. And what you lose initially is mostly the gains that you’ve made in the last several months of training.

What exactly does that mean? If you’re a lifelong runner, you’ll retain much of your aerobic fitness for several months. So don’t worry: You won’t revert to a couch potato if you need to take a few weeks off due to an injury like IT Band Syndrome.

More: 3 Ways to Conquer IT Band Pain

Here’s even better news: The better shape you’re in, the more fitness you’ll hold onto when you’re not running. If you run consistently and have a higher level of fitness than a beginner, you don’t have to worry about losing your gains as much as if you were just starting out.

The best use of this information is to run as consistently as possible. Running is truly a long-term endeavor—a lifestyle rather than simply a sport—and your aerobic fitness is something you hold onto for many months.

More: Should You Run More Miles?

How Quickly You Lose Structural Fitness

Structural fitness is critical for injury prevention. It helps you absorb the impact of running without suffering an overuse injury.

This area hasn’t been studied as well, but it does take longer to gain structural fitness as opposed to endurance. Many runners experience more rapid declines in this area as well.

More: Hip Strengthening and Mobility Exercises for Runners

This means that for any period of inactivity, your body’s ability to tolerate running declines more quickly than its ability to run. This puts you in the injury danger zone.

Any runner will recognize the euphoric feeling you get after five to seven days off from running. You go for your first run and feel great. After all, you’ve rested for about a week. You may even be running a little faster than usual because it feels better than your usual, slower pace.

But after a week of faster running and feeling good, aches and pains pop up. You may even experience an injury because your structural fitness is much lower than your aerobic fitness.

More: How to Manage Aches and Pains During Training

So what are you to do?

During any period of inactivity, a small amount of strength work can help you maintain your body’s ability to withstand running. A short gym workout or a series of medicine ball exercises can often mean the difference between staying healthy and taking even more time off because of a running injury.

Once you understand that your endurance is lost slower than your structural strength, you can modify your training to run more consistently. And the more consistently you run, the more fitness you’ll have.

More: How to Become a Consistent Runner and Nail New PRs

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Runners obsession – running! Just one day of no running and we go ‘oh no, I’m unfit!’. We start to freak out, we become jittery and we begin questioning out fitness. It is all runners’ biggest fear – to lose our hard built fitness. So how much fitness do we actually lose if we take a break from running?

The Good News

Great news for runners – according to running coach Jack Daniels – a 5 day break from the sport will not hurt your running fitness at all. So if you’re down with the flu, a break will do you more good than harm. Fear not, you won’t lose your fitness!

No Running For More Than 6 Weeks?

If injury comes into play forcing you to take a long break from running, how fast you lose your fitness depends on 2 factors – how long you’ve been running and how fit you were when you had to stop running. Someone who is a veteran runner will not lose his fitness as fast as someone who has just started out running – of course.


Photo Credits: Uncyclopaedia

A study on detraining over a 12 week period was conducted. The results show that in the initial stages, there is steep drop in VO2 Max. Thereafter, the declines were smaller. In 12 days, VO2 Max dropped by 7 per cent, thereafter, it was small declines till it hit 18 per cent. However, there is no loss of capillary density in muscles which is great news!


This study was detraining study was conducted with zero training. If during your no-run period, you cross-train, fitness loss would be far less. Choose a regimen that suits your situation -aqua jogging, swimming or even cycling.


A 5 day break from running won’t cause you to lose your fitness! Don’t freak out about it. Sometimes rest does us more good. Remember that rest and recovery is part and parcel of training. However if you are forced to take a prolong break, do remember to cross-train. This is to slow down your loss of fitness! Your running fitness does stay with you, don’t worry!

Your goal race is just two months away, and you’ve been crushing your training all season long. You’re feeling strong, fast, and fit – not to mention more confident than you’ve felt in years.

But then life happens. Maybe you get sick and sidelined for a while, or perhaps an injury decides to knock you off your plan. Or maybe work deadlines, family obligations, and other commitments start to take precedence over your precious training time. What does that mean for your training, your fitness, and your rapidly approaching race day?

Read on for the lowdown on losing fitness – and how to regain your strength.

It takes more than a few days to start losing fitness

If you’re generally fit, don’t panic about missing a few days of training. Even if they’re crucial ones, like tempo days or long run days. But if you start missing more, your fitness will eventually begin to dwindle. (Muscle memory doesn’t last forever, after all.)

“It’s safe to say that within two weeks, an endurance athlete can see a significant degradation in fitness,” says Jonathan Cane, exercise physiologist and founder of City Coach Multisport in New York City.

After a day of missed workouts, not much will change, Cane says. But after two weeks, you may experience a decrease in VO2 max and lactate threshold, as well as changes in blood enzymes associated with cardiovascular fitness.

Go a month sans fitness and you can expect significantly decreased glycogen storage – “if not sooner,” Cane adds. (Studies have shown that after four weeks of inactivity, endurance cyclists saw a 20 percent decrease in their VO2 max. After 12 days of inactivity their blood enzymes associated with endurance performance decreased by 50 percent.)

If you’ve been sidelined for a year, Cane says your blood volume will likely have returned to “normal, pre-training levels”. Capillary density appears to be pretty resilient with detraining, but it will likely show significant losses over that much time.

A sign of losing fitness

So beyond your workouts feeling a little harder once you get back at it, how do you know that you’ve lost aerobic fitness?

“There are some variables you can easily measure,” says Cane. “Resting heart rate is one good indicator.” If your resting heart rate has significantly increased during your time off, there’s a good chance the fitness you worked hard to build has started to fade.

How to avoid losing fitness

The good news for regular exercisers is that as much as it may hurt trying to get back in shape, it’s easier for once-fit people to bounce back into shape than it is for people who rarely work out.

As much as it may hurt trying to get back in shape, it’s easier for once-fit people to bounce back.

“It’s definitely harder to start from scratch,” Cane says. “Even months of detraining won’t take you back to the levels of a sedentary person.”

Age is a factor, too: Older people lose fitness faster, and younger people generally regain it quicker.

So what can you do to avoid being totally sedentary during forced time off? “Cross-train if possible when you’re injured,” Cane advises. When you can’t run, ask your doctor if you can swim, bike, or strength train. If cycling is out, ask about yoga or Pilates.

“If you’re simply too busy to commit to normal training time, try to at least slow the losses with short, intense bouts of exercise,” Cane suggests. “Depending on your sport and your goals that may not be enough to maintain your fitness, but it will at least help stem the tide.”

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Please note that the information provided in the Polar Blog articles cannot replace individual advice from health professionals. Please consult your physician before starting a new fitness program.


Yes, you can improve your fitness with just a few workouts, especially if you’re not in great shape to begin with and you’re looking to boost endurance or cardiovascular health. If you’re already near the top of your game, or your goal is to improve your strength, it may take a bit longer to reach that next level.

“The data’s a lot more straightforward for aerobic exercise than it is for weight training,” says Douglas Van Pelt, a doctoral student at the University of Michigan School of Kinesiology. “In as little as one to two weeks, you can definitely see measurable results for things like your 5K time, for example, or your exercise capacity—like the wattage you can output on a bike’s power meter.”

A lot of these differences come from very early adaptations of the cardiovascular system, Van Pelt explains. He cites a 1991 NASA study that shows how blood volume increases can occur after just eight days of training.

“A larger blood volume increases your cardiac output, and therefore your aerobic capacity,” he says. “The quick increase, even after a few days, can be very beneficial to exercise capacity and performance.”

Of course, results like this only happen when you really push yourself. This is known as the Overload Principle: the idea that the body can only adapt and improve if it’s pushed beyond what it’s done before. That’s why it’s harder to see or feel improvements if you’re already a decent athlete.

“If you take somebody who’s a couch potato and you start them on a training program, any stimulus you give them will deliver results much faster than someone who’s very close to their true maximal exercise capacity,” says Van Pelt.

Regardless of your current shape, high-intensity interval training is probably the most effective way to boost your fitness in a short period of time. In fact, research shows HIIT can deliver measurable differences in exercise performance in as little as six sessions over two weeks.

Each and every workout stimulates the body at a genetic level, as well. RNA and proteins important for skeletal muscle adaptation and aerobic capacity respond in as little as one exercise session, says Van Pelt, and continue to change within the first week of a new routine.

When it comes to strength training, seeing real improvements may take a bit longer—up to four weeks, according to a 1994 Ohio University study. “This can be highly variable among individuals, so it’s hard to make sweeping statements about” how long it will take until you see measurable results, says Van Pelt.

But that doesn’t mean you can’t benefit from your first week of weight lifting, says personal trainer Peter Park, co-author of Foundation and former strength coach to Lance Armstrong and Matthew McConaughey. On the contrary, you can see measurable results in your first few sessions, simply by learning proper form and technique.

“If someone’s been doing squats incorrectly—breathing at the wrong time or bringing their knees too far forward—I can instantly improve their strength output by probably 30 percent, by teaching them the right cues,” says Park. The same goes for working out efficiently with free weights or machines at the gym, he adds.

Van Pelt agrees that many of the physiological adaptations in the first few weeks of a strength routine are neurological, rather than muscular. “I’d allow three to four weeks minimum before you really reassess your performance or start to add weights or reps,” he says. “If you overload your muscles too soon, you’ll create more soreness, and you’ll have a harder time recovering and rebuilding those proteins.”

One more thing, while we’re on the subject: If you’re asking this because you’ve got a race or competition in a week and you’re hoping to eke out some last-minute gains, you may want to reconsider. You’re likely to do more harm than good at this point, so tapering—at least for a few days beforehand—is probably your best bet.

Bottom line: “As long as the exercise you’re doing is difficult enough to stress your body and force it to adapt, you can definitely see changes in a week or two,” says Van Pelt. “They may be small changes, but depending on the level you’re starting at, I’d say up to a 10-percent increase is possible.”

Lead Photo: martin-dm/iStock

How long you need to do cardio to reap the benefits for your body and brain

Aerobic exercise, or “cardio,” might be the closest thing to a miracle drug that we have.

A growing body of research suggests that when we commit to regular workouts that raise our heart rate and get us moving and sweating for a sustained period of time, magical things happen to our body and brain.

We think more clearly, feel better overall, and protect ourselves against some of the cognitive decline that occurs with age, studies suggest.

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“Aerobic exercise … has a unique capacity to exhilarate and relax, to provide stimulation and calm, to counter depression and dissipate stress,” the authors of an article in the Harvard Medical School blog “Mind and Mood” wrote.

But how long should you be cycling, swimming, walking, or running to reap these benefits?

Overall, research suggests that the magic happens somewhere in the window of about 30-45 minutes at minimum.

Aa recent paper looked at the exercise habits of hundreds of breast cancer survivors who were experiencing symptoms like “chemo brain,” which involves memory loss and trouble focusing. The researchers found that as little as 30 minutes of an aerobic exercise like walking was linked with significantly better performance on cognitive quizzes.

Another study published in May provided some additional support for that research — it found that in adults aged 60-88, walking for 30 minutes four days a week for 12 weeks appeared to strengthen connectivity in a region of the brain where weakened connections have been linked to memory loss.

Similarly, a pilot study in people with severe depression found that just 30 minutes of treadmill walking for 10 consecutive days appeared to be “sufficient to produce a clinically relevant and statistically significant reduction in depression.”

Other research suggests it might be better to do cardio for longer. A study in the British Medical Journal found that in adults over 50, the best results for the brain appeared to come from a routine that combined aerobic exercises with resistance training (i.e. muscle-building exercises like planks and push-ups) and lasted at least 45 minutes.

Researchers still aren’t sure why this type of exercise appears to provide a boost to the brain, but some studies suggest it has to do with increased blood flow, which provides our minds with fresh energy and oxygen. One recent study in older women who displayed potential symptoms of dementia also found that aerobic exercise was linked with an increase in the size of the hippocampus, a brain area involved in learning and memory. Another reason might have to do with cardio’s ability to help reduce levels of the body’s natural stress hormones, such as adrenaline and cortisol, according to a recent study in the Journal of Physical Therapy Science.

Joe Northey, the lead author of the British study and an exercise scientist at the University of Canberra, said his research suggests that anyone in good health over age 50 should do 45 minutes to an hour of aerobic exercise “on as many days of the week as feasible.”

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3 Ways To Skyrocket Your Cardio Intensity!

When I walk into my gym, I often see familiar faces walking on the treadmills or methodically cranking away on the elliptical machines. When I finish my workout, these same people are still working the same equipment. And unfortunately, these people are usually still carrying the same body fat they had when I joined two years ago.

I can’t help but shake my head. If you’ve been following the same program for months and you’re not seeing any change. Why would you continue to follow the same exact program? You’ve no doubt heard Albert Einstein’s quote about insanity, that it’s doing the same thing over and over again and expecting different results. Watching the same bad television shows over and over again and expecting to wake up thin strikes me as equally cuckoo. I’m left wondering if “results” even factor into these individuals’ mindsets anymore.

Personally, I can’t think of anything more boring than endless low-intensity steady state cardio—especially inside a gym. I have the patience of a chipmunk, so if I had to spend an hour on one piece of cardio equipment, I’d probably tie a noose to the pull-up bar. Luckily, research has shown that steady-state cardio is not the best way to burn fat, and it may even eat away at your hard-earned muscle.

So what’s the alternative? Don’t drop the walking entirely. Instead, break it up with a few brief explosions of athleticism. It may not be fun at first, and your motivation will be tested to the limit. But ask yourself: Shouldn’t training feel this way?

The Imperative For Greater Intensity

High-intensity interval training consists of short bursts of all-out effort alternated with short periods of low-effort “recovery” time. HIIT has been around for decades under different names and variations, but it raced to mainstream prominence in recent years thanks to a steady stream of research showcasing a host of benefits.

Interval training has been shown to burn fat while preserving muscle mass, increase circulating growth hormone in the body, greatly improve cardiovascular capacity, and increase the metabolic rate for hours or even days. But these don’t even cover my favorite part about HIIT: that it can take less than 20 minutes.

It sounds like magic, and for this reason, all kinds of fit people have been recommending HIIT to all kinds of non-fit people. My message to novices: Don’t jump in too quickly, because HIIT can be taxing on the central nervous system. Ease into it as you would if you returned to heavy lifting after an extended layoff. I also suggest no more than two HIIT sessions per week, especially if you’re also hitting the weights hard.

Got that? Then let’s fire the starting gun.

Option 1: Go On A Sprint-Walk

Sprint-walks are the classic example of HIIT training that can be done just about anywhere. If you have access to a track, you could sprint the straightaways and walk the curves. If a track isn’t your style, just sprint in any direction and then walk back to the same starting point. I do this in the parking lot at my gym after my resistance work.

Warm your body up by running at a slow-to-medium pace for about 5 minutes. The sprint portions should last between 10-20 seconds, and the walk portion could last between 20 seconds and 2 minutes, depending on your fitness level and the progression of your training session. The walk portions tend to increase as the session unfolds.

If that sounds like a lot of timing and measuring, use the infrastructure to your advantage by running along a road. My running route has telephone poles spaced every 100 feet. I use them as my markers.

Three phone poles is roughly equivalent to a 100-yard dash, which takes me about 15 seconds (OK, so I’m not Usain Bolt, but neither are you). After that, I’ll walk for a series of phone poles until I feel I can sprint again.

It’s just as simple as it sounds, but use caution if you’re not accustomed to sprinting. Sprinting is a dynamic movement that’s notorious for causing injuries such as ankle sprains and tears of the Achilles tendon, hip flexor, and hamstrings (how many baseball players have you seen pulling up lame after legging out a hit?). Most muscle tears are a result of your CNS triggering a muscle to contract at the wrong time in a dynamic movement, so it’s crucial to give your nervous system time to gradually adapt.

Accelerate in a controlled manor and avoid jackrabbit starts, especially on your first training session. Otherwise, you’ll find yourself limping home mumbling all kinds of nasty things about me and my bright ideas.

Option 2: Sprint Up, Walk Down

At first, that hill may seem insurmountable, but once you reach the top and see how far you came, the fear dies. After that, you’ll just want to climb it faster.

Step 1

Find a steep hill. You probably have one within a half-mile or so of your house, even if you’ve never noticed it. It doesn’t have to be much. Walter Payton did sprints in a landfill for crying out loud, so keep an open mind.

Step 2

Jog to the hill and then run up it as fast as you can. You’ll be warmed up by the time you reach the top. You might feel like you’re barely able to imagine running it again, because hill sprints generate a tremendous pump in the legs, very quickly.

Step 3

Walk back down the hill and repeat as many times as you can. The great thing about hill sprints is that they dictate the pace of your run. After four repetitions, my heart always feels like it’s going to burst out of my chest. The light jog back to your house is your cool-down.

Option 3: Ride the Machines

You might think that I’m going to advocate sprint-walks on a treadmill here, but honestly, I find that it’s a pain to have to press the buttons and change the speed. Instead, I think intervals work best on machines where you set the pace, such as bikes or elliptical machines.

For interval training, ellipticals and bikes work better than treadmills; it’s just easier to switch speeds.

If I use a stationary bike, I choose “Quick Start” and set the resistance to the highest level so it’s difficult to pedal. After a warm-up of 5 minutes or so, I’ll start my sprint phase by standing up and pedaling as fast as I can for 30 seconds.

Then I’ll sit down and pedal for 30 seconds at a slow pace for my “walk” phase. There are many different sprint-rest combinations you can try, but I find that after 20 minutes of 30/30, my legs will be so pumped I can barely walk.

On an elliptical, again use “Quick Start” and increase the resistance. However, I recommend not holding the moving handles, because they limit your sprinting speed.

You can hold the stationary handles but I prefer not to hold on to anything, because it increases core activation and will improve your balance.

Again, perform 30 seconds of sprinting followed by 30 seconds at a slow pace. At the end of some of the “walk” phases, I’ll come to a stop and reverse direction. You’ll find that you can’t sprint as fast in reverse, but it stresses your leg muscles in a much different manner.

Suffer And Love it

I’ve always been of the opinion that if you hate doing something, you won’t do it for long, so you’d better find some way to do it that you don’t hate quite so much. So yeah, HIIT has more benefits and it takes less time than traditional cardio, but if you’re serious about it, prepare for a grueling workout.

At least you’re in good company. Back in 1796 the French writer Madame de Stael was asked her opinion of steady-state cardio vs. HIIT, or something, and she simply stated “One must, in one’s life, make a choice between boredom and suffering.”

How quickly does cardio improve?

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