Summertime is vacation time, which often means air travel. But traveling by plane also means long stretches without stretching (or any other form of physical activity).

        Elizabeth Chumtong, a gift shop owner in Clifton, travels to Thailand each summer to visit her husband's family and to buy merchandise. Flying 20 hours each way not only gives her jet lag, but, as Ms. Chumtong says, “My body gets really knotty and tense from staying in one position, and I get muscle fatigue.

        “When I'm in a layover, I sit down and stretch out, but in the airplane I don't feel like I can move — I don't have the room.”

RESOURCES

Books     • Jet Smarter: The Air Traveler's Rx (Flyana Rhyme; $14.95) by Diana Fairechild. • Exercises for Airplanes: And Other Confined Spaces (Excalibur; $8.95) by Janet Diamond. • Fitness for Travelers: The Ultimate Workout Guide for the Road (Houghton Mifflin; $14) by Suzanne Schlosberg.     Deep Vein Thrombosis (DVT)     In 2001, the World Health Organization announced its 2½-year study of the association between DVT and air travel. Some evidence suggests that being inactive for long periods during a flight may cause blood to pool in the lower legs and feet, increasing the chance of dangerous clotting.     DVT is most common in the lower limbs and may occur without any obvious signs or symptoms. The general symptoms are pain, swelling and discoloration of the effected limb. It can mimic many other medical conditions, and expert investigation is required to confirm the diagnosis.     Exercise resources     • The Flight Flexor is one example of in-flight exercise equipment. This small resistance exercise unit from Innovative Fitness weighs less than a pound and fits in a travel bag.     To use it, you place the device on the floor in front of you and compress the flexor with one or both feet. It can double as a footrest when not being compressed. The compressing action flexes muscles in the legs, increasing blood return from the legs to the heart. $49.95 (877) 222-817; Web site.

        In the last year, focus on this fitness quandary has intensified because of an international debate about Deep Vein Thrombosis (DVT), also known as “Economy Class Syndrome.”

        This life-threatening condition of blood clots in the leg or chest has been linked to confinement during lengthy airplane travel and has prompted airlines such as British Airways, Singapore Airlines and Qantas to promote in-flight exercises. Other companies are producing in-flight exercise equipment and books on the subject.

        Most experts recommend that airplane passengers wear loose, comfortable clothing, avoid crossing their legs while seated and walk briefly around the airplane cabin whenever possible.

        Being in good shape, exercising (especially stretching) on the days before you travel, and not overtraining the day before flying can help travelers stay loose and comfortable at 30,000 feet.

        Whether you are concerned about preventing DVT or just want to arrive at your destination feeling less like a human pretzel, here are some simple Pilates-based stretching exercises created for British Airways' “Well-Being In The Air” program:

        Sit correctly — Place a pillow in the hollow of your lower back to keep the natural curves of your spine. Sit tall and with your weight evenly balanced on each buttock. Keep shoulders relaxed. Breathe into your sides, and as you breathe out, hollow your lower abdominals back toward your spine. Breathe normally now, keeping the abdominals “scooped.”

        Neck rolls — Sit back in your seat and against the headrest. Gently and slowly allow your head to roll to one side (do not force it) then back through the center and toward the other side. Try to keep the back of your neck long and your shoulders relaxed. Repeat several times.

        Ankle circles — Sit tall in your seat. Place the pillow under your right thigh, just above the knee, keep your weight even. Now circle your right foot, keeping the whole leg as still as possible. Make 10 circles in each direction. Switch the pillow to under your left thigh, and repeat with the left foot.

        Calf exercise — Still sitting tall, take your foot back underneath the seat a little, keeping it in a line with your knee and hip. Keeping the foot flat, push the toes and ball of your foot into the floor, hold for a count of five, then release. Now push your heel into the floor for a count of five, release. Repeat these two actions with the knee at a right angle and with the leg stretched out a little, again in a line with the knee and hip. You should feel the work deep in your calf.

        Shoulder circles — Sit tall, but move forward a little in your seat. Bring your shoulders up toward your ears then circle them back downward. Imagine you have pencils on the tips of your shoulders and you have to draw big circles. Repeat six times, then lift the shoulders toward your ears and drop them back down six times.

        Standing — Stand tall, feet parallel and a hip-width apart. Come up onto your toes. Think tall as you lower your heels back down. Bend knees, so they are directly over the center of each foot. Your heels should stay down and your feet should not roll in or out. Try not to stick your buttocks out, or tuck them under. Slowly straighten the legs to return to the starting position. Repeat 10 times.

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