Training on Fatigued Legs Builds Durability—as Long as You Do It Right. Experts Explain How.

Jump to:The Benefits of Running on Tired LegsTips to Practice Pushing Through FatigueHow to Know if Your Legs Actually Need a BreakWhy You Need to Make the Most of Rest DaysMost runners know the feeling: dragging yourself out for a jog when your legs feel like lead.Your calendar says it’s supposed to be an easy day, but your quads seem to have missed the memo. You settle into a shuffle, wondering how a pace that felt effortless last week could demand so much today.“Running on tired legs means that your body is in a state of recovery following an effort or stimulus,” says Brad Whitley, DPT, a doctor of physical therapy and clinic director at Bespoke Treatments in San Diego. That effort might come from a hard run or strength session, but emotional and work stress can also contribute, he says.A run in that state isn’t necessarily a bad idea. Practicing on tired legs can help prepare you for the later miles of a race, when you no longer feel fresh. The trick is knowing when pushing through fatigue is useful to performance—and when a rest day will do you more good.The Benefits of Running on Tired LegsSimply put, running through some fatigue makes you stronger, both physically and psychologically.“Running on tired legs helps build resilience in the muscular system,” explains Victoria Sekely, DPT, CSCS, a doctor of physical therapy and certified run coach based in New York City. A more resilient muscular system means your muscles can not only recover faster, but also carry you longer and at a quicker clip.“When your legs are tired, your muscles are undergoing a biophysiological change,” Sekely explains, which includes building stronger muscle fibers. “If you keep going past that fatigue, that will end in a positive adaptation—meaning you can start to run longer without the fatigue setting in.”Whitley agrees and highlights the mental benefits: “One of the benefits of running on tired legs can be psychological—that is, teaching your central and peripheral nervous systems [the brain, spinal cord, and all nerves that extend to the rest of the body] that you are able to operate with higher levels of fatigue,” says Whitley. “This is helpful for longer races like a half marathon, marathon, ultramarathon, Ironman, and more.”Tips to Practice Pushing Through FatigueWhile it has its benefits, this training tactic requires thoughtful execution to avoid overtraining or injury.Whatever you do, if you’re running on tired legs, keep the effort easy. “As a rule of thumb, runners shouldn’t complete high-intensity sprints or long threshold sessions when fatigued, as these types of workouts are when muscle strains can happen,” advises Whitley.Here are a few strategies for how to practice running on tired legs.Run in the Morning; Lift in the Evening“Initially, the best way to introduce training on fatigued legs would be to complete a run in the morning and a whole-body and/or lower-extremity strength session in the afternoon,” says Whitley. “This allows time for some recovery to occur and then would stress a different physiological system in the afternoon.”It can feel difficult, but your body will become more resilient as the muscle and tendon capacity increases.Run Easy the Day After a Hard RunThe easiest strategy to try running on tired legs is simply to schedule an easy run right after a long training run or speed workout.“Running on tired legs is mainly for runners who run more than four days a week, and it will naturally happen if you’re following something along the lines of the 80/20 guideline, where 80 percent of your runs are easy and 20 percent are hard,” says Sekely. “On the days that are hard and followed up with an easy day, your legs will most likely feel fatigued. You are certainly at an increased risk of injury on that day, which is why it’s imperative to keep that easy day easy.”Try Two-a-DaysIf you’re increasing mileage or prepping for a long-distance race, consider running twice in one day. “Make the morning run a priority, and the p.m. run can be done at an aerobic pace—think zone 1 to 2—to make up for volume needed for the day,” says Whitley.How to Know if Your Legs Actually Need a BreakThere’s a fine line between training smart and overtraining. If you’re not fueling properly or skimping on rest, pushing through fatigue is going to backfire, says Sekely.“It’s important to recognize if you need a rest day—all athletes I work with implement at least one or two rest days every seven to 10 days,” she says. “Every runner benefits from rest days as much as they do easy days.”Plus, adds Whitley, too much training when you’re feeling tired can mean you’re chronically overtrained—and leave you burned out or with an overuse injury.So before you head out with heavy legs, check in on a few variables:Be Real About Your FeelingsCheck in with your emotional state before you head out for your run. “If you’re noticing it is incredibly hard to get motivated and you’re having difficulty getting out the door, this might be a sign of chronic fatigue, and you should modify your training schedule,” says Whitley.Don’t be afraid to take a day or two off, so you feel ready to get back out there.Practice the 10-Minute RuleThis is a good guideline to gauge whether you’d benefit more from a run or rest on any given day, says Whitley: If you start your run with moderately fatigued legs and find that you’re not feeling better after moving for 10 minutes, modify the run by making it lower effort (slowing the pace or eliminating hills), or cut it short if you’re seriously struggling.Check Your HRVHeart rate variability measures your individual readiness compared to yourself, and many smartwatches have features to help you easily track yours. If your HRV is way off from your average, Whitley advises opting for a rest day.Why You Need to Make the Most of Rest DaysWhen you do call it a day and kick your legs up instead of lacing up to log some miles, remember that you’re not slacking; rest is when the real gains happen.To get the biggest boost from your time off, Whitley recommends thinking about how you can reduce the root cause of your fatigue—whether that’s doing gentle yoga or getting a massage for sore muscles or meditating to clear a mind that’s been overwhelmed with work stress.At the end of the day, running on tired legs isn’t about pushing through at all costs—it’s about knowing when to lean into discomfort for growth and when to pull back to avoid burnout.Laurel Leicht is a writer and editor in Brooklyn. She's covered health, fitness, and travel for outlets including Well+Good, Glamour, and O, The Oprah Magazine.