Fall marathon season is here. Thousands of athletes — from the swiftest to those at the back-of-the-pack — are training to take on the challenge of running 26.2 miles. If you are among them, you probably aren’t thinking beyond crossing that finish line. Perhaps you should.

The moments after you finish a marathon can be euphoric. But the hours and days that follow can bring a world of pain: Your legs will hurt, and so will your arms. Walking will be difficult; stairs — even street curbs — will seem insurmountable. Your feet — and your toenails — will take a beating.

“For some people, especially novice runners, it’s the most sore they will ever be in their lives,” said Scott Trappe, director of the human performance laboratory and a professor of human bioenergetics at Ball State University. “Recovery is one of the more underutilized aspects in a runner’s toolbox. You need to take it just as seriously as your training.”

Running a marathon is a grueling event, for first-timers in particular. The biggest effect is on the muscles. Running depletes them of glycogen — the stored form of glucose — the muscles’ main source of energy. The prolonged pounding of legs and feet on pavement, especially running downhill, also causes microscopic muscle tears.

Running a marathon stresses the heart, lungs and the body’s thermoregulatory system that controls internal body temperature.

“The peak function of all of these systems is reduced for hours and at least a few days after you run a marathon,” said Michael J. Joyner, a physiologist and an anesthesiologist at the Mayo Clinic in Rochester, Minn.

We asked sports medicine experts as well as a few experienced marathoners — to share their tips for a successful recovery:

What is best for pain relief after a race?

If you must take something for pain relief, don’t take an NSAID (nonsteroidal anti-inflammatory), but stick to acetaminophen, which does not affect inflammation, said experts, who believe that inflammation promotes healing.

“There’s no question NSAIDs interfere with a few of the muscle pathways involved in muscle buildup, turnover and recovery,” Trappe said. “After a marathon, if the discomfort is considerable, go with the acetaminophen over the NSAID.”

“NSAIDs can interfere with the natural healing process,” said John L. Ferrell III, director of sports medicine at Regenerative Orthopedic Sports Medicine, which has several locations in the Washington area. “Also, while they can provide temporary relief, they come with potential risks like gastritis and acute kidney injury.”

What causes postmarathon soreness?

For years, a buildup of lactic acid (lactate) — a chemical produced when cells break down carbohydrates — has been blamed for postmarathon muscle-burning and soreness. It is also a myth, experts say.

“What you are feeling in your muscles is the result of pounding, microtrauma and energy depletion,” Trappe said. “Lactate is not the bad molecule everyone has made it out to be. Lactate production is actually relatively low from running marathons.”

Lactic acid “probably plays a part in soreness, but its role has been overblown,” Ferrell said.

Should you take an ice bath or a warm shower?

Some athletes sink into a tub of ice following a rough game or other intense competition. But “the emerging consensus is that warm, not cold, is better,” Joyner said. “Whether this speeds recovery at the cellular level or just helps people feel better is an open question.”

Ferrell recommends starting with heat “because it increases the blood flow,” he said. “You don’t want to tamp down inflammation immediately, but once the healing process is underway, you can use ice after a couple of days.”

Amby Burfoot, who won the 1968 Boston Marathon and is still running them at 78, heads straight for the hot tub.

“My body is stiff and sore, and the warm water feels very comforting,” he said. “I’m not going to do anything to stress my leg muscles the next several weeks, so I don’t have to think about ice and anti-inflammatories and that sort of thing.”

Should you run or not run the day after?

The fastest runners often do — their talent, training and body type enable them to bounce back quickly — but it’s probably not a good idea for the rest of us.

“Elite runners have put a lot more miles in, and they also are lighter,” Trappe said. Moreover, having trained for the pounding, “the overall trauma for them is not as significant,” he said.

“They’re out on the course for less time,” he said. “They are still beat up but not as much compared to a four-hour recreational runner. The recovery profile is definitely different.”

Don’t underestimate the healing power of rest. Most runners should take it easy and give their body two to four weeks to return to normal, he added.

He and others recommend light “cross-training” activities in the days following a marathon, such as swimming, walking and easy spin cycling.

“Savor your accomplishment and go on a period of active rest, which means modest levels of physical activity and stretching until the snap in your legs comes back,” Joyner said.

Burfoot, who has run about 75 marathons (he’s lost count), starts with very easy recumbent bicycling, spin cycling and elliptical workouts a few days postmarathon.

“Nothing hard or high-resistance,” he said. “Maybe I’ll do three to four miles of walking a day in my second week, then begin running the third week. In the old days, I wanted to return to training as soon as possible to get ready for the next starting line. Now my first thought is: ‘I can’t wait to begin my two-week layoff.’”

Should you get a massage?

Some research suggests massages help while others say the effects are inconclusive.

“It feels good, if not too aggressive, and may be a nice reward to enjoy and certainly has a placebo effect,” Trappe said. “It may be beneficial, but the verdict is still out from a science perspective.”

Does it take longer to recover the older you get?

“The older you get, the longer it takes” to recover, Trappe said. “We also get smarter and tend to respect the process more.”

Joan Benoit Samuelson, 67, won the inaugural women’s Olympic marathon in 1984 and ran the Tokyo Marathon in March.

“You can’t run the miles and expect to recover fully both in training for and running a marathon,” she said. “Don’t set high expectations. Cross-train before and after running a marathon. Don’t think you can carry high-mileage training weeks forever.”

What should you eat after a marathon?

For the first 72 hours, refuel your depleted muscles with calories and fluids. Trappe recommends healthy food — complex carbohydrates such as fruits and vegetables, and items that are low in saturated fat — but he understands not everyone will do this because “you want to reward yourself and go out for a pizza and a shake.”

Cheryl Bimler Link, 62, a retired health care information technology specialist from Dublin, Ohio, said she quickly forgot her postmarathon pain after a friend gave her a bloody mary in the runners’ tent.

“The tomato juice and salt settled my stomach and had me feeling great,” she said. “Or maybe it was the vodka.”

Connie Chan, 70, a retired university professor from Orleans, Mass., who has run 33 marathons, said she eats whatever she wants for a couple of days, “including sandwiches with french fries and maybe onion rings” — before returning to a healthy diet.

Mary Harada, a retired history professor from Durham, N.H. warns against binges. Decades ago, after her last marathon, she ate an entire frozen cheesecake.

“It was the most stupid thing I ever did after a marathon,” she said.

How can you cope with the postmarathon letdown?

“Postmarathon blues are real,” Trappe said. “You’ve been focused on this big goal, and now you don’t have that purpose anymore.” He suggests planning ahead for something big soon after, such as a vacation, “just to give your mind something else to do.”

Julia Kim, 65, a technology executive from Boston, spends two days “swearing: never again,” then signs up for another one.

Burfoot said these days he feels grateful after every marathon, never sad.

“I appreciate that I was able to reach another marathon finish and thankful I still have the fitness and strength to cover 26.2 miles,” he said. “And I’m hopeful I’ll be able to do it again in the next year.”