Fall is the ideal season for running. Cool temperatures put less stress on your body, so you'll go faster and farther with less perceived effort. In fact, a study in Medicine & Science in Sports & Exercise that analyzed marathoners' finish times found that their performances slowed as the mercury rose. Taking your workout outdoors has other benefits, too: Fresh air, greenery and water improve mental well-being and even elevate self-esteem, according to studies published in Environmental Science & Technology.

Ready to lace up and explore new terrain? Emma Coburn, the Olympian and three-time USA Track & Field outdoor champion shown here, will inspire you to try one of these six track and trail workouts designed to improve speed, rev your metabolism and tone muscles. Happy trails! —Gina Demillo Wagner

Right: Vest, $135, shorts, $40, watch, $150, and sneakers, $110; NewBalance.com. New Balance HKNB sports bra, $50; NewBalance.com

Styled by Lindsey Frugier. Hair and makeup, John Mckay for Chanel Les Beiges Powder and Karestase.

The Workouts

GET FASTER: STRAIGHTAWAYS & CURVES
Sprinting trains your legs to turn over (a running term for move) faster, which improves overall speed and efficiency on longer runs. Plus, working those fast-twitch fibers gives your legs better overall definition. This 2-mile routine is ideal for the track, because you'll know where to start and finish: Warm up with a one-lap jog followed by four 100-meter strides, then run six laps at varying pace: Sprint the straightaways at an intensity level of 9 out of 10, and jog or walk the curves at level 3 or lower. add this drill to your routine twice a week to get speedier and boost metabolism for hours. "Sprint workouts can help decrease body fat, too," says personal trainer Laurie Villarreal, founder of HouseOfRunning.com.

TORCH CALORIES: SPEED PLAY
This workout, ­also known as a fartlek, can help you run farther than you thought you could by distracting you with constantly changing speeds. After a two-lap easy warm-up, pick an arbitrary benchmark—every lap, every lightpost or every jogger you pass, for instance—as a signal to speed up or slow down, experimenting with different paces. Switching it up each time you hit your mark will increase the overall calorie burn of your workout, Villarreal says. Aim for 20 times around the track; that's 5 miles and 500 to 600 calories burned!

TONE ALL OVER: RUNNING-DRILL MASH-UP
Joe Friel, founder of Training Bible Coaching and author of Your First Triathlon, recommends this dynamic track workout that combines running, plyometrics and resistance training: For your first lap, run the curves at level 5, then do walking lunges, butt kicks, squat jumps or side shuffles on the straights. On lap two, jog at level 3 until you hit a line or number in the lane (every 100 meters), then do 5 burpees. Do a tempo run for all of lap three, then head to the bleachers for 3 sets of 10 elevated push-ups­—hands on the first row, feet on the ground. For an extra challenge, turn around and do decline push-ups.