Core stability workout
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Credit: Photograph by Justin Steele

Stabilizer muscles in your hips, back, and shoulders have critical jobs, like supporting your spine and joints under the jolting and jarring of pickup basketball, tennis, trail running, or just about anything else you might do for fun on the weekend. That makes a core-focused interval session the single most time-efficient training and a solid foundation if you're looking to get back in shape. Note that our routine begins with a total-body exercise, then moves to a lower-body exercise, then an upper-body exercise, and, finally, a core exercise, before repeating the pattern. "That basic sequence is important so that you can always do the next exercise with good intensity," says Chris Jordan, who built this routine based on published scientific research on interval and circuit training. The complete circuit should take four minutes, and Jordan recommends doing it for about 20 minutes. "But don't do this routine on consecutive days," he says. "The muscles need one clear day in between, to recover and repair."

The Routine
Perform each exercise at a vigorous intensity for 30 seconds. Move to the next exercise with minimal to no rest in between (5-10 seconds, tops). When you've completed the entire circuit, start again immediately. Repeat the circuit four to five times.

1. Mountain climbers
2. Two-leg/regular squat
3. One-leg triceps dip
4. Bird dog
5. Plyo split squat
6. Side lunge
7. Staggered push-up
8. Side plank