4 personal trainers say the secret to a strong core is not to focus solely on your abs — here are their favorite exercises for a toned tummy

• Compound exercises like squats and deadlifts do well to target your abs while working out.
• If you want to focus on additional core work, consider adding up to three ab workouts per week.

When it comes to strength training, moderation is key. Otherwise, you risk overdoing it and hurting yourself.

However, the core is a little different. "The abdominal muscles are very resilient to overuse," says Vanessa Mandell Windt, an ISSA-certified personal trainer who trains clients online.

So, technically, you can do ab exercises daily, Mandell Windt says. However, you'll be in much better shape if you don't just do a ton of crunches every day.

Below, I spoke to four personal trainers for their expertise on how best to strengthen your core.

How often should you do ab exercises each week?

You can strengthen your core with various exercises on a daily basis. But if you want defined abs, then avoid doing only ab workouts.

Instead incorporate full-body strength workouts that emphasize freeweight exercises like dumbbell squats and chest presses.

"The abs get activated and work in almost all freeweight exercises, so you can see significant gains without completely isolating the abs," Mandell Windt says. "I'd argue that full-body workouts and heavy compound exercises are more effective for strong and visible abs than crunches and sit-ups."

Compound exercises are those that recruit multiple joints and muscle groups.

And the core is almost always involved in compound exercises because your abdominals work closely with other muscles in your core, such as the glutes, spinal erectors (the muscles that straighten your back), and multifidus (small muscles located on either side of your spinal column).

If you want to focus on hitting your abs outside of the work they get from compound exercises, Rachel MacPherson, an ACE-certified personal trainer with Garage Gym Reviews, suggests incorporating up to three days of dedicated ab work per week. Start by adding one ab workout to your existing routine and increase as you're able.

Should you focus on different ab areas each time?

It's tough to target one specific ab muscle, "because the goal is to make them all work together," says Nicole Pruchnik, a performance coach with the personal training app, Future. Still, you can emphasize certain muscles more than others based on their function, she adds.

For instance:

• The rectus abdominis bends (flexes) the trunk and is targeted in crunches, McGill curl-ups, and sit-ups.
• The obliques rotate the trunk and can be worked with bicycle crunches, side bends, wood chops, and Russian twists.
• The transverse abdominis helps stabilize the trunk and is the primary focus in forearm planks and hollow-body holds.

Performing compound strength exercises like squats, deadlifts, shoulder presses, lunges, push-ups, and pull-ups is one of the best ways to target your ab muscles.

Other ab exercises that engage multiple core muscles include bird-dogs and hip lifts. Bird-dog, for example, works the entire core, including the glutes and even the back, Mandell Windt says.

Hip lift also hits the glutes and core muscles. "The goal is to have the back flat when lying on the floor, so tuck the hips by squeezing the core and glutes at the same time," Pruchnik says.

Quick tip: According to MacPherson, other great ab and core exercises include hanging leg raises, rollouts, woodchops, kettlebell halos, and bear crawls.

The benefits of ab workouts

Ab and core workouts are a vital part of any fitness regimen, so it's important not to neglect them when you plot your weekly routine.

These muscles have many important roles, from stabilizing your trunk (the central part of your body including chest, back, and pelvis) during heavy squats to helping you balance in everyday life.

Here's more on the perks of hitting your abs and core in your workouts.

Prevents back pain and injury

Strengthening your core helps prevent back pain and injury. "Your core works as a unit to stabilize your lower back and pelvis," MacPherson says.

Without strong core muscles, your body has to rely more on your spine and pelvis for stability during exercise and daily activities. This can cause lower back pain and injury.

Improves daily function and exercise performance

Regular ab and core work can make everyday activities and exercise easier.

"All movement originates from your core, so anything you do with your limbs, such as lifting grocery bags or throwing a ball, requires your abdominals and other core muscles to brace to keep your spine stable," MacPherson says.

If you can boost your ab and core strength, you'll notice these activities seem a bit easier.

Tones your midsection

Ab exercises can help you build bigger, more defined muscles. However, there's one important caveat: You can't get rid of belly fat through ab workouts, MacPherson says.

Dave Candy, a certified athletic trainer and board-certified specialist in orthopedic physical therapy, agrees. "If your goal is to have a flat stomach and a six-pack, diet has much more to do with that than exercise," he says.

So, if you want your ab muscles to pop, you'll have to pair your workouts with a healthy diet.

Proper form is important

One downside to doing ab exercises comes from doing them with poor form. This often happens when people rush their reps.

"When you rush through the reps and don't get a chance to engage the ab muscles correctly, the lower back has a tendency to take over the load, which can lead to lower back pain and injuries," Mandell Windt says.

To avoid pain and reap maximum benefits, perform ab exercises at a slow and controlled pace, "and make sure you feel the abs fire with each and every rep," Mandell Windt says.

It's also important not to do the "wrong" ab exercises, Mandell Windt says. "As a trainer, I see many otherwise sedentary people do sit-ups and crunches religiously."

When you spend long stretches of your day in a seated position, your shoulders and upper back tend to round forward. This causes your chest muscles and your front hip muscles (known as the hip flexors) to tighten, Mandell Windt says.

High reps of crunches and sit-ups may strengthen ab muscles but they also shorten your chest and hip flexors even more.

So, if you're sedentary during the day, you may benefit more from core exercises like bird-dog or Pallof press that stretch your hip flexors and chest, while strengthening your shoulders and upper back, Mandell Windt says.

Insider's takeaway

Strengthening the abdominals and other core muscles can yield major benefits, including pain and injury prevention and improved performance in sports and daily life.

Ab exercises can also help you build a more defined midsection, provided you're paying attention to your diet.

Your abs already get plenty of attention in compound strength and core-focused exercises. However, if you want to focus on your abs even more, add up to three days of dedicated ab work per week.

Aim to target the entirety of your core equally, and be sure to prioritize good form.