Want a stronger core? Skip the sit-ups

Sit-ups once ruled as the way to tighter abs and a slimmer waistline, while “planks” were merely flooring. Now planks — exercises in which you assume a position and hold it — are the gold standard for working your core, while classic sit-ups and crunches have fallen out of favor. Why the shift?

One reason is that sit-ups are hard on your back — by pushing your curved spine against the floor and by working your hip flexors, the muscles that run from the thighs to the lumbar vertebrae in the lower back. When hip flexors are too strong or too tight, they tug on the lower spine which can be a source of lower back discomfort.

Second, planks recruit a better balance of muscles on the front, sides, and back of the body during exercise than sit-ups, which target just a few muscles. Remember, your core goes far beyond your abdominal muscles.

Finally, activities of daily living, as well as sports and recreational activities, call on your muscles to work together, not in isolation. Sit-ups or crunches strengthen just a few muscle groups. Through dynamic patterns of movement, a good core workout helps strengthen the entire set of core muscles — the muscles you rely on for daily activities as well as sports and recreational activities.

Core workout can cause muscle soreness

Many popular workouts that aim to strengthen your arms, legs, and abs give short shrift to many of the muscles that form your body’s core (the group of muscles that form the sturdy central link connecting your upper and lower body). Strong core muscles are essential to improving performance in almost any sport — and are the secret to sidestepping debilitating back pain.

If you haven’t been working your core muscles regularly — or if you challenge yourself with a new set of exercises — expect to feel a little soreness as you get used to your new routine.

Extremely sore muscles a day or two after a core workout means you probably overdid it and might need to dial down your workout a bit. Next time, try to finish just one full set of each exercise in the workout. You might also do fewer repetitions (reps) of the exercises you find especially hard. Once you can do reps without much soreness, build strength by adding one more rep of the harder exercises in each session until you’re doing the full number of reps comfortably. Then try adding a second set.

If your muscles feel really sore within 24 to 48 hours of adding a burst of core work, cut back on the number of reps. For example, say you are doing planks, the modern alternative to pushups. Instead of trying to do four front planks a day, start with one. Stick with that for a few days, then add a second plank. When you’re comfortable at that level — that is, not feeling a lot of muscle soreness — add a third plank. And so on. If even one plank knocks you out, cut back on how long you hold it: instead of 30 seconds, try 10 seconds for several days, then try 15 or 20 seconds, and so on.

Delayed-onset muscle soreness is a normal response to working your muscles. Usually, it peaks 24 to 48 hours after a workout before gradually easing, then disappearing entirely in another day or so. But if you experience sudden, sharp, or long-lasting pain, check with your doctor