Running on Full : Hints for outfitting a favorite rambling recreationalist, who makes fun a serious business.

There is no end to the add-on gadgets and thingamajigs that accompany today’s recreational activities. And because most recreational enthusiasts spend their disposable income on the essentials, such as running shoes and bike tires, the December holidays are the perfect time to indulge them with an assortment of gizmos.

For last-minute shoppers who can’t deal with crowded malls and packed parking lots, the ever-increasing number of catalogues is a godsend. Virtually all catalogues offer toll-free ordering and next-day delivery for an extra charge.

Electronic gadgetry can take a lot of the frustrating math out of setting your own goals. The Electronic Pedometer from Sportline allows the hiker to dial in the desired number of calories to burn. The lightweight pedometer then displays how many were burned during the exercise, along with steps taken. It’s also a countdown timer and stopwatch ($50 at The Nature Co., South Coast Plaza, Costa Mesa).

Many runners dislike having to stop to replace their vital fluids. For them, the Fanny Flasque from Seirus may be the answer. It’s a soft nylon one-quart flask that straps on as does a hip pack, with a drinking tube to eliminate the need to grope for zippers or bottles. It’s machine-washable and holds hot or cold drinks ($23 from the Road Runner Sports catalogue, (800) 551-5558).

And finally there’s something to give a golf fanatic besides a dozen balls. For the many golfers who like to keep their individual score while playing, the Score-Keeping Golfer’s Watch is ideal.

The golfer just presses a button at the end of each hole, and the 18-hole score can later be analyzed for individual holes, front and back nine and total playing time. It’s also a digital quartz watch ($45 from the Hammacher Schlemmer catalogue, (800) 543-3366).

The Heart Rate Cycling Computer HR 1000, from Vetta, performs all the usual functions of an on-bike computer, including speed, elapsed time, time of day and miles traveled. But simply attach a strap to your chest, and it measures your heart rate while you’re cycling ($100 at Bicycles Etc. in Lake Forest and San Clemente).

At the risk of letting a machine tell you what’s what, the Pulse Monitor/AM-FM Radio actually announces the exerciser’s heart rate at 20- or 60-second intervals while he or she listens to music. The belt unit weighs 14 ounces and includes earphones. Fits chests to 54 inches ($150 at Brookstone, South Coast Plaza).

The Oakley Subzero, at just a half-ounce, is possibly the world’s lightest quality sunglasses. They offer full ultraviolet protection ($99 at Bicycles Etc.).

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And now that you’ve collected all these gadgets, where can you put them?

The Sima Sports Pouch is a vibration-proof and waterproof bag for carrying cameras, sunglasses, portable cassette players, keys and other valuables. Perfect for kayakers and canoeists, the high-visibility pouch claims to keep up to 10 pounds afloat ($18 at Impulse, Crystal Court, Costa Mesa).

As a humorous antidote to the machismo that has infected some members of the mountain biking community, “Mountain Biking for Mere Mortals” is Michael Hodgson’s unorthodox look at the foibles and travails that Mr. and Mrs. Weekend encounter on the trails (ICS Bks. Inc., $7 at Bicycles Etc.).

The threat of illness from drinking unpure water is every camper’s nightmare. In response to this problem, water purifiers have evolved to become more efficient and lightweight.

The Pur Explorer uses an iodine cartridge to kill viruses, bacteria and microorganisms such as Giardia. It can purify a liter of water per minute, features a circular intake that resists clogging and has a built-in brush for quick cleaning ($130 at the North Face, Crystal Court).

For exercisers who tend to their business after dark, the Zelco Personal Alarm and Flashlight sends out a screaming signal in case of distress. It’s also a key chain ($17 at Rand McNally Maps, South Coast Plaza).

A far smaller key chain from Silva features a tiny compass and thermometer ($9 at the North Face, Crystal Court).

For nighttime jogging, cycling or walking, Cue Lite’s Jogalite provides lightweight protection by flashing long-lasting LEDs for 200 hours. Using two AAA batteries, it straps to the arm or leg, out of the way ($15 from the Road Runner Sports catalogue, (800) 551-5558).

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The golfer on your gift list can kiss those plastic practice balls goodby.

The Instant Driving Range is an 8-by-10-foot net that can withstand the hardest back-yard drives. Shock-corded fiberglass poles allow easy setup, and it folds into a two-foot-long box. Also can be used for soccer or baseball ($80 from the Paragon catalogue, (800) 343-3095).

The skier who has everything probably doesn’t have a pair of Stop Watch Ski Grips. A digital watch is built right into one grip top, while the other holds a stopwatch for timing runs. Designed for any adult Alpine-type ski pole, the grips use cold-weather batteries, which are included ($30 from the Hammacher Schlemmer catalogue, (800) 543-3366).

Finally, after a hard day’s workout, the Brookstone Muscle Massager prepares the body for tomorrow’s action. The cordless massager allows hands-free use, and the circular vibrator pad permits various levels of pressure ($16 at Brookstone).