Think of trail running as road running amplified.
Like all running, trail running increases muscular strength and endurance in your quads, hamstrings, calves and glutes, in addition to giving your heart and lungs a workout. But because the trails serve up an unpredictable, rocky, root-filled terrain of hills, streams and other natural obstacles, trail running improves your proprioception (your sense of balance and where your body is in space). It also taps nearly every muscle from your shoulders on down, and builds strength in your joints. As a result, it provides a challenging whole-body workout.