Getting fit isn't instant — but some workout benefits appear almost immediately. As for the rest, how long it takes to get in shape depends in large part on where you're starting from and how much effort you put in — but you can start seeing measurable effects in a matter of weeks.
While some of the benefits of exercise are immediate, it usually takes a couple of weeks for the first measurable results to begin showing in your cardiovascular fitness and muscular strength or endurance. But don't stop there: The more you work out, the more health benefits you'll enjoy.
Some Immediate Benefits of Exercise
Have you ever walked out of a fitness class or the gym weight room, or perhaps put away your bike helmet or running shoes, and thought to yourself "I feel better now"? That reduction in stress and surge in your mood are two well-known benefits of being active, and they often take effect before your workout is even over.
If you struggle with chronic pain from arthritis or other conditions, the right type of exercise may provide immediate relief. And the Centers for Disease Control and Prevention points out that the beneficial effect of exercise on your blood sugar can also be immediate.
If you're exercising for weight loss those effects are immediate too, even if they're not easy to measure in the short term. Every single workout or healthy nutrition choice you make is a tiny step in the right direction on your fitness journey, and they really do add up — just as any unhealthy choices add up too.
But don't beat yourself up if you backslide every once in a while: Nobody's perfect all the time. Just remember that every healthy choice you make is a tiny success in its own right, and all it takes to turn a string of negative choices around — or continue a streak of good choices — is one healthy decision.
"Get Fit" Equals Exercise Adaptation
When you talk about the longer-term benefits of getting fit, what that really means is exercise adaptation: Your body has adapted to the stress of physical activity and is now better able to handle it. If you stress your body with strength-training workouts, it'll get stronger. Stress its muscular endurance, and it'll respond by developing more.
Your heart is a muscle too, so expose it to the stress of cardiovascular workouts and it'll also build greater strength and endurance. Have you exposed your muscles to the "stress" of gentle, appropriate stretching? That's how you improve your flexibility.
As the experts at ExRx.net point out, your body can adapt to almost any natural stress as long as a few conditions are met. Those include warming up the appropriate joints or muscles before you work out, applying sufficient stress during the training bout and allowing enough recovery time between trainings.
Just as important, you also need to provide appropriate levels of stress (if you've just started weightlifting, it's not time to do a full version of Arnold Schwarzenegger's workouts) and regularly increase those levels, slightly increasing the challenge every time your body adapts.
A certain amount of variation is necessary too, so that your body will continue adapting. That's why techniques like cross-training — or branching out into different sports and physical activities to vary the stress on your body — are so helpful.
Your Timeline for Heart Health
There are several different ways to measure fitness — so it might not be surprising to know that the timeline for each of those measures can be a little different. When it comes to cardiovascular fitness, exercisers anecdotally mention that their workouts start to feel significantly easier within a couple of weeks.
That correlates nicely with a small study published in the July 2018 issue of the International Journal of Environmental Research and Public Health. The study involved 13 physically inactive subjects who tackled either a program of high-intensity interval training (HIIT) or of moderate-intensity continuous cardio.
Researchers reported that both groups showed significant improvement in heart rate variability by the end of the two-week testing period. Or to put it another way, their hearts got better at regulating themselves in just two weeks.
Although both groups showed improvement in such a short time, it's worth noting that the group who participated in HIIT training showed significantly more improvement. If you're looking for a time-efficient way to turbocharge your cardiovascular fitness, HIIT may be it.
That doesn't mean the benefits of cardiovascular exercise plateau just two weeks after you start. Quite the contrary: The more you work out at appropriate levels, the more fit you'll become.
Get Fit With Weights
When you first hit the weights, it's typical to see some serious gains within the first couple of weeks. But as Len Kravitz, Ph.D., an exercise physiologist with the University of New Mexico explains in his article, those near-immediate weight gains are usually the result of neural adaptations, or the result of your body training your muscles to respond more efficiently to the challenge of weightlifting.
But don't worry: Long-term gains in muscle size and strength are about eight weeks away if you're training twice a week. That also happens to be the minimum duration for most clinical studies of muscular strength and endurance, because it gives your body enough time to generate measurable, clinically significant results.
However, there is a catch: Just walking into the weight room and looking at the weights isn't going to help you. You need to actually lift them — or lift your own body weight, if you prefer resistance-training exercises like push-ups, pull-ups and lunges — enough to challenge your muscles, but not so much that you hurt yourself.
A good target is to do one to three sets of eight to 12 repetitions for each muscle group, and train all your major muscle groups (chest, back, arms, shoulders, core, hips, thighs, calves) in every workout.
How Much Exercise?
So, what's an appropriate amount of exercise to get fit? The most important thing you can do is get up and move. Any amount of movement, even 30 seconds or a minute, is good for you. So, start with whatever you're capable of — whether that means an hour-long run or a five-minute walk around the block — and then slowly increase either the duration, intensity or frequency (how many times a day or week) of your workouts as your body adapts.
Once you're ready to set your sights on a longer-term goal, aim to satisfy the Department of Health and Human Services (HHS) guidelines for physical activity. They recommend getting at least 150 minutes of moderate-intensity cardiovascular activity per week, or 75 minutes of vigorous-intensity cardio. If you can work your way gradually up to double those amounts, you'll see even more health benefits from being fit.
The HHS also recommend strength-training your major muscle groups at least twice a week. And although those guidelines don't specifically mention stretching, if you add a post-workout stretching session to your workouts at least two or three times a week, you'll be well on your way to improving your flexibility too.
Is This an Emergency?
- Centers for Disease Control and Prevention: "Make Your Workout Work for You"
- Mayo Clinic: "Aerobic Exercise: Top 10 Reasons to Get Physical"
- ExRx.net: "Exercise Adaptation"
- International Journal of Environmental Research and Public Health: "The Effects of High-Intensity Interval Training vs. Moderate-Intensity Continuous Training on Heart Rate Variability in Physically Inactive Adults"
- American Council on Exercise: "High-Intensity Interval Training: Why It Works"
- Health.gov: "Physical Activity Guidelines for Americans"
- University of New Mexico: "Resistance Training: Adaptations and Health Implications"