Whether you welcome it or dread it, speedwork does a runner's body good. "More than any other type of training, speedwork is the most effective at building your fitness because it really pushes you out of your comfort zone," says Andrew Kastor, an Asics running coach in Mammoth Lakes, California.

"You recruit muscle tissue that lies dormant during slow running and train your body to become more efficient at faster paces." Unfortunately for many runners, speedwork is synonymous with track—a venue that's often unavailable, inconvenient, or frankly, intimidating. But you don't need a synthetic oval to get your fast fix. Here are four ways to shore up your speed without running in circles.

Races & Places
Asphalt is everywhere. And if you race, doing speedwork on the road best simulates the impact and conditions you'll face. Of course, it can take a toll on your body. "The road can beat up your legs, but that's what you want—up to a point—as this makes you stronger," says Kastor.

Half-mile repeats at your goal 5-K pace with a quarter-mile jog recovery. "The recovery is long enough to clear most of the lactic acid from your muscles, but short enough to keep the workout challenging," says Kastor. Beginners should do three or four repeats; more advanced runners can run up to 10 repeats. Measure the distance with a GPS or mapmyrun.com, or run by time (for example, if your 5-K pace is 8:00, run four minutes hard and recover with two to three minutes of jogging).

Best Hoka Running Shoes
"Trails always offer better scenery than the roads or track," says Nancy Hobbs, coauthor of The Ultimate Guide to Trail Running. "They're also easier on your legs, and they improve balance, coordination, and mental focus." You do have to stay vigilant, however, as unstable or slick terrain can cause missteps—or worse.

Trail fartleks. Do this workout on a stretch of gradually ascending trail. To build strength, run fast uphill; to increase your turnover, run fast on the downhills, says Hobbs. Jog for 10 minutes, then go hard (about 10-K pace, or a speed that feels moderately hard) for 30 seconds, easy for 30, hard for 60, easy for 30, hard for 90, easy for 30. That's one set. Perform three to 10 sets.

What Is a Reverse Taper
With the trusty TM, weather is never a limiting factor and "the forgiving surface allows you to recover from speedwork more quickly," says Kastor. On the flip side, mills can be boring, many don't adjust to simulate downhill running, and the belt's movement alters how you use your hamstrings, says Kastor. "This could lead to muscle weaknesses or imbalances if you're on the treadmill all the time."

Progression run. "The idea is to gradually get to a level where you're really working," says Kastor. Do a 10-minute warmup jog at about 12-to 15-minutes-per-mile pace, depending on your ability. Then increase the speed by .1 or .2 miles per hour every minute for five to 10 minutes. Decrease the speed and jog or walk for one minute. Begin the next progression at the speed in which you ended the first phase. Again, increase by .1 to .2 mph every minute for five to 10 minutes. Jog for two minutes. Begin the final progression at the speed in which you ended the second phase. Cool down with a five-minute jog.

OFF YOUR FEET
Doing speedwork on a bike, elliptical machine, stairclimber, or in the pool delivers a significant cardiovascular boost without impact. If you're injured, it's a great way to maintain your fitness.

Cardio sprint pyramid. After a 10-minute warmup on the cross-training tool of your choice, go hard for 30 seconds, one minute, two minutes, four minutes, two minutes, one minute, 30 seconds. After each hard segment, go easy for the same amount of time. "Your intensity should be an 8 or 10, where 1 is sitting and 10 is all-out sprinting," says Jason Karp, Ph.D., a coach and personal trainer in San Diego. "Aim for an 8 on the longer segments, and 10 on the shortest." Newbies should stick to a single set, advanced runners can do up to three (go easy for three minutes between sets).