Here’s How to Stay Fit When You’re on the Road : Hotels and cruise lines have upgraded their exercise programs so travelers won’t miss a beat.

James Graves usually works out by lifting weights and climbing stairs at a stadium near his office. During a recent trip to Mexico, with no stadiums or weight machines in sight, Graves had to improvise by swimming in the motel pool and walking, every chance he got. The upshot was that unlike many American travelers, Graves returned feeling almost as fit as when he left home.

As an exercise researcher at the University of Florida, Graves is painfully aware of what some vacationers try hard to forget: that a sedentary vacation can sap strength and leave people in good condition feeling untrained and winded when they return home to regular workouts. And perhaps more importantly, they can rather quickly lose much of the conditioning they worked so hard to achieve.

“If you are a fit individual, you can probably get by without any exercise on a one-week vacation,” Graves said. But even after one inactive week, the most fit person will lose some of his or her edge.

Remain inactive on a long vacation, and you can lose as much as half of your aerobic conditioning, according to a University of Florida study that found fit college professors who stopped exercising over the summer had a 50% reduction in aerobic conditioning after just three months. And surprisingly, most of that decline seemed to occur during the first four weeks of inactivity, rather than evenly over the course of time.

Add to that the need to balance out the increased calorie intake that often occurs on vacation and you have two solid reasons for trying to get regular exercise.

Fortunately, it is becoming increasingly easy to work out on the road as hotels, cruise lines and other facilities create exercise opportunities that are almost as good as those we have at home.

Exercise needn’t be difficult to set up. The newly renovated St. Regis Hotel in Manhattan has a 24-hour fitness center stocked with treadmills, stair climbing machines, weights and other equipment, said Jose Donato, who manages the center. One-on-one training is available from 6 a.m. to 9:30 p.m. and guests who stay a week or longer can request delivery of an exercise bike, rower or stair climbing machine to their rooms. It’s all included in the room rates, which start at $350 per day.

But you don’t have to spend nearly that much to find a hotel with a basic fitness center. Less costly hotels are more likely than in years past to have exercise centers, too. “More than half of the ‘traditional’ Holiday Inns have exercise facilities,” said Holiday Inn spokeswoman Gayle MacIntyre. “All our Crowne Plaza Hotels do.” The boom in exercise options has been fueled not just by vacationers, MacIntyre said, but also by business travelers. There has even been discussion about introducing executive rooms with amenities such as exercise equipment, MacIntyre said.

Even moderately priced lodgings, such as the YMCA, have taken steps to make exercise options more accessible. About five years ago, the YMCA introduced its AWAY (Always Welcome at the Y) program, which allows members to use the facilities of other Ys free or for a nominal fee, said Lynne Vaughan, associate director of health and fitness for the YMCA. Before departure, vacationers should ask at their own Y to see the international directory of other Ys, she suggested.

It’s getting easier for overseas travelers to work out if they choose a newer hotel, said Joe Hickman, director of corporate marketing for Conrad Hotels, the international subsidiary of Hilton Hotels, Inc. “Most new hotels overseas are being built with outstanding health care facilities,” said Hickman. Guests at Conrad Hotels in London and Istanbul, for instance, will find jogging maps in their rooms, extensive fitness centers on site and menus filled with health-conscious entrees, he said.

Another hotel, the Grand Hotel Victoria-Jungfrau in Interlaken, Switzerland, has just opened a new fitness center that includes an indoor swimming pool, outdoor whirlpools, a sauna and steam bath, plus a team of doctors, nutritionists and other health experts to help guests exercise and eat prudently while abroad.

Even aerobics enthusiasts can find places to work out in Europe.

“The best way to find an aerobics class overseas is to look in local publications such as Time Out in England or Paris Passion in France,” said Alison Schecter, a New York journalist and aerobics instructor who travels frequently. Look in those publications under health or exercise centers.

Dedicated runners who have made do by jogging through hotel corridors and around parking lots, now have another alternative. In May, the American Running and Fitness Assn. introduced its running trails network, a service that provides maps of running paths in various locations nationwide. “We already have maps of 150 cities,” said spokeswoman Lisa Gundling. “Trail lengths vary, but average 5 or 10 miles.” Runners are invited to submit maps of their favorite trails in exchange for a free trail map of their destination city. Send $1 to receive a map to the Running Trails Network, 9310 Old Georgetown Road, Bethesda, Md. 20814. (To find out if there is a map available for your destination city, call the association at 800-776-ARFA.)

Walkers who want company on their vacation strolls can find out whether their destination has a mall walkers’ organization, said Tom Cabot, president of the National Organization of Mall Walkers. There are about 3,000 malls in the United States, Cabot estimated, and more than 2,000 have organized walking clubs. Call the mall information desk and ask if there is a walkers’ group, Cabot advised.

Many cruise lines now cultivate exercise options, not just fork-to-mouth workouts. “We’ve always had exercise facilities on ship, but not as extensive as now,” said Jennifer de la Cruz, a spokeswoman for Carnival Cruise Lines.

Two of the line’s vessels now include workout rooms with high-tech, air-powered exercise machines, allowing exercisers to do a full-strength workout. The rooms aren’t tucked into corners on dark lower levels, de la Cruz said, but are on upper decks in windowed rooms, allowing exercisers to work out while enjoying a view of the ocean. Aqua aerobics and traditional aerobics classes are also offered, along with an upper-deck, 1/8-mile oval jogging track.

Whatever your vacation routine, most experts agree you don’t need to work out as frequently as you do at home. “The intensity of the workout is the key” to maintaining fitness, Graves said. “You can get by with cutting back on frequency and duration but you need to maintain the intensity (to preserve fitness),” he said.