You can't give the people you love the gift of health, but you can buy them something to help keep fit. From the whimsical to the practical, these items may trigger the imagination and spark increased activity levels in their recipients. And no one need know if you should happen to buy one of these gadgets for yourself. KEEPING TRACK

Sticking to a diet and exercise regimen can be tough. There's a definite psychological lift, as well as numerous practical benefits, to monitoring your accomplishments.

*One measure of physiological stress is heart rate. You can determine your exercise heart rate -- without stopping your workout -- with this device, which attaches a pulse sensor to one finger. An electronic beeper keeps you informed of your activity level while you exercise. $80. Eddie Bauer. For mail order, call 800-426-8020. Item #5805E in Holiday Catalog. Shipping extra. *Runalert is a two-ounce device that clips to your running shorts or belt to measure the stress impact of your stride while running or jogging. If you are hitting the ground too hard for your weight, a warning beeper sounds until your step is lightened. $30. Eddie Bauer. For mail order, call 800-426-8020. Item #A711E in Holdiay catalog. Shipping extra.

*Seiko's Quartz Pulsemeter will measure your pulse when you touch it, or you can attach electrodes to your chest. You can also set its automatic pacer to beep at any rate from 5 to 299 times per minute, if you want to perform an activity like rowing with even, consistent strokes. Also works as a stopwatch. And, by the way, it tells time. One-year warranty. $125. Eddie Bauer.$129. The Sharper Image. For mail order, call 800-344-4444. Item #SK001. Shipping, $3.50

*For those who tend to cheat with the old-fashioned adjustable bathroom scale -- putting it on an angle, standing on one foot, or setting it two pounds light -- the Weight Talker allows no such messing around. This electronic scale has a pleasant male voice and can remember weights for up to five people. It tells you to the pound (or half-kilogram) how much you've gained or lost. Then it says, "Have a nice day," which probably depends, for some of us at least, if we weighed in higher or lower. One-year warranty. Requires seven AA batteries, not included. $99. The Sharper Image.For mail order, call 800-344-4444. Item #TZ357. Shipping $5.50.

*This digital diet scale weighs food precisely in 0.1-ounce or 1-gram increments.. White plastic base. Black panel with red LED display. $68. The Paragon (mail order). Call 401-596-0134. Item #3220. Shipping $7.45.

*Food Informer is a hand-held nutrition guide. Punch in one of more than 650 foods and drinks. The gadget's "burnoff mode" will tell you the number of minutes it takes to burn off the corresponding calories in 17 activities, including tennis, alpine skiing, golf and sex. The eight-digit LCD also gives calories, carbohydrates, cholesterol, fat, fiber, protein and sodium for the selected food. $149. The Sharper Image. The Shops at National Place. Mail order, call 800-344-4444. Item #DB650. Shipping $3.50.

*Play it safe before you or a friend drinks then drives. The Alcohol Tester by Lumiscope estimates the alcohol content of your breath. The guide lights green if all is clear, amber for caution, and red if the level is too high to drive safely. Comes with six AA batteries and a 12-volt car battery adapter. $79.95. Innovations (mail order). 800-638-6170 outside Maryland, 301-363-4300 in Maryland. Shipping $3.95. OFF-THE-BEAT

There are dozens of obvious fitness gifts most exercisers would love -- sweatsuits, weights, leotards, leg warmers, head bands, fitness books, videos, equipment, exercise classes, health club memberships, massage and sports bags. Or choose a gift from among these not-so-obvious items:

*This one's a little like giving a bottle of mouthwash. Stinky Pinkys are the remedy for an athlete's, shall we say, obtrusive sneakers. These reusable, odorless mineral sacks detoxify shoes overnight. Two pair per package. $11.95. Boston Proper Mail Order. 800-243-4300. Item #B1372. Shipping $2.95.

*Staying Inflated. Anyone who has played tennis knows there's nothing worse than flat balls for wrecking an otherwise phenomenal game. This tennis ball saver promises to keep them "Factory Fresh" for up to six months -- instead of the average two-week life span of a tennis ball. It looks like a yellow thermos and is designed to hold three tennis balls. $12. Arthur Ashe & Friends. White Flint Mall, Tysons Corner and 19th Street downtown.

*Lighting Up. Night runners will be easier for cars to spot if they wear a special safety vest in orange mesh. Two battery-operated strips -- one in front and one in back -- light up and blink. These Velcro light strips peel off for washing. Elastic sides assure a good fit. Nite Runner Vest. $15. Boston Proper Mail Order. 800-243-4300. Item #B1247. Shipping $2.95.

*Like to play golf after sunset? Try these illuminated golf balls for nighttime use. By Spaulding, with six holes in each ball for insertion of three green fluorescent light sticks. Each stick gives off six to eight hours of bright light, and glows for 24 hours. Set of three balls with nine light sticks. $15. Trifles (mail order). 800-527-0277. Item #HL961. Shipping $1.75. Ten extra light sticks cost $7.50. Item #HL481. Plus $1.75 shipping.

*Want weights to match an exercise outfit? "Beauti-Bells" from Joe Weider in fuchsia or lavender. These rubber-coated dumbbells come in three-, five- and eight-pound weights, at $14, $16 and $28 respectively.

A three-pound gift set sells for $35. (suggested retail price) and includes a pair of three-pound fuchsia Beauti-Bells, fuchsia and blue ankle and wrist weights, and a nylon skip rope with fuchsia and blue handles.

The five-pound gift set, at $39, includes a pair of five-pound lavender Beauti-Bells with color coordinated weights and skip rope in lavender and jade green. Available at J.C. Penney and Park Lane Hosiery. Or by mail from Weider Health & Fitness. 800-423-5713. Shipping extra.

*For guaranteed returns, sports enthusiasts might enjoy a boomerang handmade in Kent, England, of ash and hardwoods. Flight tested to ensure accurate return, this lightweight -- 4.6 ounce -- boomerang has a throwing range of 30 yards. You must specify whether the user is left- or right-handed. If you don't know the answer, then perhaps this is too personal a selection. $20. Abercrombie & Fitch. Georgetown Park Mall.

*You could give a bowling ball to one of that sport's aficionados. Or give something more original, at least outside of Italy. Try a Bocce (pronounced botch-ee) ball set -- an Italian game of lawn bowling. Played outdoors, this can be an alternative to American horseshoes. Set comes with eight balls (four for each team) a target ball and a rulebook. $125. Abercrombie & Fitch. THE ULTIMATE

Fitness fantasies are among the most exciting daydreams. We imagine ourselves thinner, stronger, more energetic. These gift suggestions cater to the fancies of those who have not only calories but also extra dollars to burn.

*If you can stand the heat, an in-home Health Mate sauna of Japanese cedar operates at 110 to 150 degrees Fahrenheit, providing relaxation to cut down on stress and relieve tension. This one has fresh air ventilation and uses 110 volt household current. It comes in two halves that latch together, then operates with a switch, thermostat and timer. 44 inches wide, 36 inches deep, 69 inches high. $3,500, which includes delivery. Abercrombie & Fitch. Georgetown Park Mall. (Not on display, but it can be ordered. Allow 14 working days for delivery.)

*Smart Dumbbells. In triple-plated 22-karat gold, these dumbbells will add luxury to the act of building powerful biceps and triceps. They come with 12 weights, four each of five, 2 1/2 and 1 1/4 lbs. All in a teak display box. $299. The Sharper Image. The Shops at National Place. For mail order, call 800-344-4444. Item #IV494. Shipping $21.50. If the gold weights are too rich for your friend's muscles, the same set is also available in chrome, and without the teak box, for $119. Item #IV450. Shipping $21.50.

*For a Big Sport. F. Scott Fitzgerald may not have approved of the sport, but for the financially fit who do, Neiman-Marcus provides thoroughbred polo ponies from the Wayman Polo Stables in San Antonio, Tex. The ponies come in chestnut, brown, black, palomino, bay or gray. These sleek, superbly trained animals begin at a mere $17,500. For couples who share the challenge of the sport, matched pairs start at $37,500. Call Neiman-Marcus. 214-573-5780.

*For armchair athletes, a unique and beautiful backgammon set made at a small factory in a mountainside town outside of Milan, Italy. The handpainted ceramic figures depict Americans in fedoras and jackets opposing Russians wearing long coats and cossack hats. The playing field is composed of flags from the United States and Soviet Union. The mahogany chest can be folded for travel or storage. $750. Abercrombie & Fitch. Georgetown Park Mall.

*Ship Shape. For many Washington workaholics, the only way to relax and escape stress is to get out of town. So make a reservation for that special person to get a healthy break on a fitness cruise. And don't forget to book the trip for two.

The ultimate of this genre is the Queen Elizabeth II -- "Golden Door Spa at Sea." This excursion incorporates the QE2's four pools, jogging track, golf driving range, paddle tennis courts and skeet shooting with the spa's separate facilities on decks six and seven, with supervised exercise and aerobic dancing, massage, lectures on relaxation techniques and nutrition, and a fully equipped gym with Nautilus equipment.

Guests can enjoy the elaborate creations of the master chefs, pastry chefs and bakers onboard. For those who want to "waist away," there is a recommended "Golden Door" selection box on lunch and dinner menus.

The Christmas cruise is 14 days out of New York, and includes stops at St. Thomas, Guadeloupe, Barbados, Grenada, Caracas and Bonaire. The most luxurious cabin with bath and verandah for this cruise costs $10,685 per person. A split-level suite is $38,350.

Other ways to sample the QE2 in 1986 include cruises from two to 11 days long. A luxury cabin with bath and verandah for just a two-day cruise in '86 is $665/person if booked before Jan. 1; the price will go up after that date.Cunard cruise line. 800-221-4770 (outside New York).

*"Cruise to Wellness." Two of these cruises are upcoming on the S.S. Rhapsody. The ship leaves Ft. Lauderdale Feb. 9, 1986, and March 9, 1986, for seven days' sailing to the Caribbean. Guests jog on teak decks, take aerobic classes, swim in two pools. Plus talks on stress management, how to stop smoking and weight management.

On land in the Virgin Islands, there's an organized island run, plus snorkeling and scuba diving, for both certified and non-certified divers. Stops include Nassau, San Juan, St. John and St. Thomas. Cost ranges from $1,085 to $1,875 per person. Single fares are 20 to 30 percent higher than double occupancy rates. Paquet French Cruises. 800-327-8111 (outside Florida).

*"Fitness & Beauty Cruise" is a theme cruise on the S.S. Norway. This once-a-year event with fitness and sports stars on board, will next occur Nov. 1 to 8, 1986. The cruise leaves Miami and makes stops in Nassau, St. Thomas, St. Maarten and a private island in the Bahamas. On every cruise made by the S.S. Norway, the activity program includes basketball and volleyball, jogging, aerobics classes, exercise classes and swimnastics. Facilities include two outdoor pools and a complete health spa with indoor pool, weight room with Universal equipment, sauna and massage. There's also a quarter-mile jogging track and one racquetball court on the ship.

The "Fitness & Beauty Cruise" will have an organized five-kilometer run in St. Thomas. Other activities in port include waterskiing, windsurfing, snorkeling, tennis, golf, water bikes, and rental sailboats. Seven-night cruise rates are $1,195 to $2,840 per person; this includes free round trip air fare from Washington via Eastern Airlines. Norwegian Caribbean Lines. 800-327-7030 (outside Florida). PREVENTING BOREDOM

Maintaining interest is a vital component in any regular exercise program, for boredom is the bane of even the best of intentions. While most intructors recommend a variety of activities to ensure a continuing challenge, there are some devices -- electronic and otherwise -- that can prove useful in keeping workouts interesting.

*To add variety to your stationary bike, Nordic Exercise Handles simulate the movements of running and cross country skiing, thus working both the upper and lower body. Adjustable aluminum arms accommodate riders of varied sizes. $69. The Sharper Image. Mail order, call 800-344-4444. Item #LG123. Shipping $4.50.

*Aiwa's AM/FM Stereo Headset. This four-ounce padded headset has a built-in radio, eliminating the need for connecting cords. Telescoping antenna pulls in radio signals for crisp, pure tones. Uses two AAA batteries, which are not included. One-year warranty. $79. The Sharper Image. The Shops at National Place. For mail order, call 800-344-4444. Item #AI210. Shipping $3.50.

*This small, lightweight AM radio slips over one ear. It has an earphone and two dials -- one for station selection, one for volume. Weighs less than an ounce, and measures 3 1/2 inches long. Battery included. $11.99. Trifles (mail order). Call 800-527-0277. Item #HH810. Shipping $1.75.

*A whole new genre of musical entertainment has evolved that's perfect for exercisers -- credit card-size radios. Like the Sony SRF-201 Walkman FM stereo radio, which is one eighth of an inch thick and 3 3/8 inches long. Volume control and power-off system. Comes with headphones, case and built-in rechargeable nickel-cadmium battery. Electronics department. $75. Neiman-Marcus. Mazza Gallerie.

*For those who can do two things at once, a Tunturi Reading Stand mounts to most exercise bikes. Made of white vinyl coated wire, the stand holds books or magazines and can accommodate diverse tastes, from the Wall Street Journal to a racy novel. $16. Abercrombie & Fitch. FOR KIDS ONLY

Children are fascinated by concepts that mimick what the grown-ups are doing. Here are a few ideas for young fitness buffs.

*The Kindersled is for very young children -- babies and toddlers -- to be pulled along in the snow by their parents. It is not for solo riding since it does not have a steering or braking mechanism. This beautifully built transport vehicle is made of handcrafted hardwoods. Bent runners and backrests lend charm to this old-fashioned but basic activity, which creates childhood memories that last a lifetime. $60. Eddie Bauer. For mail order, call 800-426-8020. Item #5089E in Holiday Catalog. Shipping and sales tax extra.

*If bouncing can be considered an aerobic exercise, a Globetrotter Junior is a fun choice for a 4- to 6-year-old. These inflatable rubber balls in green or blue have two rubber handles, permitting a child to sit on one and bounce while holding on. Made in Italy. $12.95. Fao Schwartz. Little leaguers aged 4 to 10 can use a 27-inch high pitching machine with a funny Baseball Kid cartoon character that automatically pitches four plastic balls in succession. Kids respond by swinging the 22-inch plastic bat. Set includes pitching figure, four balls, bat and batteries. $30. The Horchow Collection. 800-527-0303. Item #L345W. Shipping $7.90. Babies give their parents plenty of exercise. Now for the newborn, white leather Nikes that come in a tin. Each pair comes with either baby blue or pink laces. The backs of the shoes zip and close with Velcro for easy dressing. Order the proper color, but don't worry about size. They are all size zero. Baby Nikes. $14.99. Foot Locker. And for little boys who want to be like their dads, a pair of high-top basketball shoes. The Baby Jordans in Sizes 2 to 8 are a take-off on the adult line of Nike shoes named for Chicago Bulls guard Michael Jordan. Multi-colored in black, red and white for 1 1/2-, 2- and 3-year-olds. $24.99. Foot Locker. STOCKING STUFFERS

Some otherwise marvelous gifts just happen to be small. And inexpensive. Still, they can be just as thoughtful, useful and enjoyable as larger, more costly gifts. An athlete can always use an extra headband, for instance, or an extra pair of ski or swim goggles. So here are a few items to fill small places. For those whose idea of a workout is "walking the dog" or "rocking the cradle," a regulation size yo-yo in silver plate is ideal. Plain, the yo-yo costs $15. With a three-initial monogram in script or block lettering, it's $23. Novelties department. Neiman-Marcus. Mazza Gallerie. Allow six weeks for monogramming. Laughter is supposed to create endorphins, which are good for your health. So for a rainy day, these entertaining rainglasses are made of white plastic frames with a battery-operated blade on each lens. And everyone has a friend who likes to look and act foolish at a party, or who runs even when it's pouring. One size fits all. Battery included. $9.50. The Horchow Collection. 800-527-0303. Item #H647V. Shipping $1.75. Desktop Workouts. No one knows exactly what goes on behind all the closed doors in offices all over town. Possibly some people are using a grip gym to develop hand strength and endurance. It can help those who participate in tennis, weightlifting, karate, rowing and golf. This chrome-plated spring steel device is shaped like a lemon. Or perhaps it's more like a lime. $4.95. Brookstone. Tysons Corner Mall. Practically speaking, runners might like to travel light, but they still need to carry a key, or money for the subway if they should tire early. A runner's Shoe Wallet in red, white, black or blue costs only $3.50. Or a Wrist Wallet, which closes with Velcro, is big enough for an I.D. at $4.50. Wrist Wallet comes in two sizes. In The Bag. 3106 M St. NW in Georgetown.