Cycling and Tired Legs

If you push yourself when cycling, leg fatigue is inevitable. But the more you train, the more endurance you'll build — and the more joy you might find in those challenging rides. And on the day after a hard speed ride, sometimes an easy recovery ride is just the thing to ease your tired legs.

The short, simple explanation for why your legs get tired: The muscles run out of ATP or adenosine triphosphate, the fuel that powers their contractions. Although the physiological mechanism by which this happens depends on whether you're doing short, intense workouts or longer submaximal workouts, the end result is the same.

Happily, the more you train, the more your muscles undergo adaptations that help them more efficiently produce and use energy. One of the key adaptations in well-trained muscles is a proliferation of mitochondria, the so-called "powerhouses of your cells" that produce energy. So the more you bike, the faster or farther you'll be able to go before experiencing cycling leg fatigue.

There's another factor that might leave your legs feeling tired when you bike. As the Hospital for Special Surgery points out, as your respiratory muscles fatigue, oxygen is redirected from your limbs to your diaphragm. Oxygen is an essential component of the reactions that fuel your cells for long-term activity, so when it goes away, so does your muscular endurance. As you train, your cardiovascular capacity will improve too, helping you feel more energized for longer.

If you're new to cycling, increasing almost any aspect of your biking — whether it's the distance, speed, duration or frequency of your rides — will build your fitness and lead to you being able to pedal faster, farther without your legs getting tired.

But if you want to get in shape quickly or improve a specific aspect of your cycling ability (for example, your power for tackling hills), then you'll get better and faster results if you undertake a strategic training program that alternates work of the appropriate intensity and duration with appropriate rest periods.

Professional athletes will want a pro coach or trainer on your side too, helping monitor your performance and adjust your training, nutrition and recovery plans as needed. However, recreational and amateur cyclists can find a great place to start in the free sample plans offered in a collaboration by professional coach Oliver Roberts and Cycling Weekly.

Read more: Biking vs. Running: What's Better for You?

It's true that if you really want your speed or endurance to develop, you have to push the limits of what your body can do in those regards — and having a focused training program can help you meet your goals faster and with less risk of injury.

But your training program shouldn't just involve speed, power or endurance rides. It should also include relatively gentle recovery rides, which are a great way to loosen up tight muscles and increase circulation ⁠— which the Mayo Clinic notes might give you at least temporary relief from soreness.

The idea behind a recovery ride after a long ride — as in, the day after — is to deliberately not push speed or endurance. Instead, as Coach Roberts explains in his fitness training plan for Cycling Weekly, the point of these "easy spins" is to take it easy and "come home feeling fresher than when you started."

Read more: Is Cycling Better Than Walking to Lose Weight?

Yes, a fast bike outing or a long bike outing — or any sufficiently intense combination of those two factors — can leave your legs feeling shaky and tired. But if you find your legs getting fatigued a lot sooner than they used to, something else might be going on. If you've ruled out medical causes, consider the following:

• Did you just increase intensity, duration or frequency? If you want your body to improve, you have to keep challenging it by progressively overloading the frequency, intensity or duration of your cycling workouts. If you've just upped one of these factors, that may account for your tired legs. But if the fatigue is excessive, you may have increased your workout difficulty too much. There's no shame in dialing back your workouts a little bit; maintaining a gradual progression — thus the term progressive overload — makes it easier for you to get fit and stay that way.

• Are you overtraining? As the American Council on Exercise notes, decreased performance and excessive fatigue are both common signs of overtraining syndrome. At its root, overtraining syndrome results from putting your body through too much exertion with too little recovery time, and can be exacerbated by poor self-care practices like not giving your body the appropriate fuel (food) for your level of exertion.

• What about self-care? Your bike workouts aren't the only factors that affect your speed and endurance. How you care for yourself in between the workouts also has a major influence on how your body adapts to the stimulus of your workouts. This includes proper nutrition, staying hydrated and, as the National Sleep Foundation points out, getting enough sleep. The proper amount of sleep doesn't just leave you feeling more energized the next morning, it can also make you faster, stronger, more alert and better coordinated.

• Is your bike set up correctly? This is of particular interest if you notice certain muscles getting tired before others — for example, if your hamstrings start to cramp up before your quads have hit that full-on burn. That might signal that your hamstrings are weak in relationship to your quadriceps — a common muscular imbalance — or it might mean that your bike saddle is too high or too far back, both of which can overload your hamstrings.

Read more: 10 Types of Low-Impact Exercise That Keep You Fit and Injury-Free

Whether you're pedaling a stationary bike in front of the TV, spinning your wheels in a group cycling class or streaking down a roadway or mountain trail, biking is infamous for making your thighs burn. But it's also a whole lot of fun.

If you're new to cycling or thinking of getting started, consider these reasons why it's well worth braving the world of tired legs and burning thighs: Not only is it a low-impact form of aerobic exercise, biking also builds leg muscles and, as Harvard Health explains, can increase bone density in your lower body.

Once you have your bike (and bike helmet) in hand, this is a sport that costs very little. Take good care of your gear, and you won't pay for much more than occasional tune-ups on your bike.

You can also scale a biking workout to suit your fitness level by adjusting an indoor bike's resistance or, if you're outside, changing gears on the bike. And finally, cycling gives you all the benefits of frequent aerobic exercise, from improved mood to a stronger immune system, weight loss and reduced risk of many chronic diseases.