Woman in side plank pose
You may be very active in the outdoors, but if you don’t have strong core muscles—the ones that stabilize your spine and basically provide the foundation for your entire body—you can’t move as efficiently and you’re more likely to get injured. Plus you’ll probably develop bad posture. So—along with crunches—use these five exercises to blast your lats, strengthen your obliques and crank up your erector spinae.

Keep your abs contracted and your back flat • hold for 60 seconds (or as long as you can) • make it harder: spread your legs, or stack one foot on top of the other

Side plank
Balance on your forearm and the side of your foot • try to hold for 45 seconds, then repeat on the other side • make it harder: fully extend your balancing arm with your palm on the ground

Keep your hands underneath your shoulders and look ahead slightly • do each up-and-down motion in two slow, controlled steps • repeat until exhaustion

Back extension
Bring your arms out to form a ‘T’ when you raise your upper body • hold for two seconds, then lower • repeat 10-15 times, but stop if you experience back pain

Double leg lift
Raise your legs to about 45 degrees and lower slowly • keep your lower back pressed against the ground • repeat 10-15 times, but again, stop if you experience back pain