Feel-Good Ideas for Long Flights : Good planning is essential. Wear comfortable clothes, exercise during the flight and drink plenty of water to avoid dehydration.

When it comes to long-distance flights, Bob Lima is an old hand at coping successfully. After a recent 12-hour flight from Los Angeles to Sao Paulo, Brazil, the Burbank travel agent did not feel exhausted, even though his port-to-port travel time, counting his trip to the airport and to his relatives’ house, was 24 hours.

His secrets? “I take off my shoes as soon as possible,” he said. “I wear very comfortable clothes. No tight belts, no new shoes. I get up and walk around three or four times. I stay calm. I eat lightly, try to take a good nap and to enjoy the movie.”

Lima has the right idea, experts say.

If you want to arrive at your long-distance destination without feeling wiped out, start planning well before departure time, advised Dr. Leonard Marcus, a travel health specialist in Newton, Mass. “If it is possible to schedule a weekend between your last day of work and travel, do so,” he said, reasoning that the lag time will help ensure that you depart feeling more rested.

“Depart in the evening, if you can, so you can sleep on the plane,” suggested Dr. Richard Bock, senior medical director of FHP, a San Fernando Valley health maintenance organization. Sleep will come easier, he added, if you avoid caffeine for four to six hours before flight time.

“Stretch before you get on the plane,” suggested Dr. Clive Segil, an orthopedic surgeon at Cedars-Sinai Medical Center and Midway Hospital Medical Center. Pay particular attention to the hamstring (the tendon at the back of the knee) and muscles of the calf, back and abdomen, Segil said.

Flying in first-class with more legroom can obviously increase your comfort level, but if that’s impossible, “It helps to have a briefcase to put under your feet,” Marcus said. Sitting in that position, he said, will relieve pressure on the spine. Consider a back support, too. Marcus advises taking along an inflatable horseshoe-shaped pillow. “If you have back problems, keep your knees higher than your hips,” Segil said.

Another problem associated with sitting: “Sitting for long periods of time increases the risk of blood clots in the leg,” Bock said. “It’s the sitting. It has nothing to do with the altitude. It can happen on buses, too.”

Swollen ankles can affect the healthiest of long-distance fliers. “Some can’t get their shoes back on,” Bock said. To decrease the risk of blood clots and swollen ankles, Bock advises moving around every couple of hours. “It can be as simple as a trip to the bathroom.” Flexing exercises are another good idea, Bock said.

One good in-seat exercise to ward off swollen ankles, according to Philip Walker of the Cooper Institute for Aerobics Research in Dallas: Lift your feet and rotate the ankles, making large circles with your toes.

Some airlines make it easier to avoid swelling and stiffness by offering in-flight fitness videos, encouraging passengers to stretch and flex along. Northwest Airlines, for example, shows “Plane Aerobics,” a five-minute video on flights exceeding 3 hours and 15 minutes. “It includes stretching and lots of upper and lower body work,” said Doug Miller, a Northwest spokesman. The video has been well-received, he added. “Generally we get about 50% participation on domestic flights and up to 95% on the U.S.-to-Asia routes.”

More recently, Lufthansa Airlines has begun showing an in-flight exercise video on long-haul international flights, according to a spokeswoman.

If your flight doesn’t include an exercise video, it’s a snap to choreograph your own routine, Walker said.

“Start with a neck circle,” he suggested, “but don’t lean your neck too far back. This relaxes the shoulder muscles, reduces tension and headaches.”

Another way to reduce stiffness: “Put your fingers on your shoulders. Rotate the elbows backward.”

Stand in the aisle. Put your hands on your hips and rotate the hips. “This is embarrassing,” Walker conceded. “Do it once the movie starts and the plane is dark. It can help relieve stiffness.”

Place your hands on your knees with feet apart; rotate knees in a circle. “This is good for the knee joints,” Walker said.

Certain people are more prone to medical problems aloft on a long-distance flight. “If you have sinus problems, they are more likely to flare up,” Bock said. “Those with severe respiratory problems are at higher risk for breathing problems.” But the good news is that heart attacks are probably no more likely to strike aloft than on the ground.

Avoiding dehydration is also important on long-haul flights. “Don’t drink alcoholic beverages,” Marcus advises, since they can encourage dehydration. “Or if you do, do so in moderation.”

Drink plenty of water, advises JoAnn Hattner, a registered dietitian at Stanford University Medical Center in Palo Alto, and a spokeswoman for the American Dietetic Assn. Avoid salty foods, too, which can increase fluid retention. “Take fresh fruits and vegetables to snack on,” Hattner said. “Consider ordering the vegetarian or low-fat meals, which probably have less salt.” Fatty foods are harder to digest, Bock explained.

Although some experts espouse an “anti-jet lag diet,” which proposes alternating feast and fast days two to four days before departing and eating certain types of foods at certain times to reset the body clock, others claim it is not effective. Some take a middle ground, suggesting that we eat foods high in carbohydrates when trying to calm ourselves and foods high in protein to rev up the system. Eating nutritiously and moderately, following the same diet we eat at home, is the best bet, others maintain.

People on medications for chronic conditions, such as diabetes, should check with their doctors before departure to determine how or if to adjust their medication schedule. At the same time, they should ask their doctors for advice on how to adjust their eating schedules during flights to accommodate new time zones.