It's a mission shared by millions of gym bunnies: to strengthen and tone the core muscles, or abs.
Most of us think that bodyweight exercises on the floor are the best way to build muscle in your core, using movements like crunches and planks.
But a growing number of fitness professionals say these exercises can be fruitless.
Instead, you're better off buying a fitness machine that not enough gym-goers use, they say.
Influencer and fitness guru Amy Kiser Schemper has more than raked in 1.5 million views with her standing ab workout that uses a kettlebell to tighten the abdominal muscles.
Fitness expert Amy Kiser Schemper has drawn millions of viewers to her workout that shows how to tighten your abs while standing up
In just 10 minutes, she says, you can “strengthen and tone your core” — without crunches, planks, or mat exercises.
A kettlebell is a large weight with a loop handle, usually made of iron or steel.
The tool is typically used to add extra resistance to bodyweight exercises that work the legs, buttocks and thighs, such as squats.
The weight is also common in workouts designed to strengthen the arms and shoulders.
But personal trainers say they are also very effective at combating stomach pain in a short time.
According to fitness trainer Sam Hopes, standing kettlebell exercises can also be gentler on the lower back compared to sit-ups.
In Ms. Kiser Schemper's video – posted by her fitness business account: BodyFitByAmythe exercise guru takes viewers through a series of exercises using a 15-pound kettlebell.
If this feels too heavy for you, she says, you can use a lighter, more comfortable weight.
Her series of exercises includes 'aaround the world' – where you rotate the kettlebell around your head.
Then there's core rotation while holding the weight, and the “windmill,” where you bend to one side and hold the kettlebell in the air.
This all works to stabilize and strengthen the core muscles, while also training the arms.
Elsewhere, fitness duo Matt Tralli and Louis Chandler (above) – who between them have over 600,000 followers on Instagram – have only posted four exercises that use kettlebells that are said to stimulate the abdominal muscles.
These include lifting the kettlebell overhead while marching and alternating shoulders with the kettlebell in hand.
They demonstrate sitting with one hand on the weight and lifting and rotating the legs around a kettlebell.
A 2013 study published in the Journal of Fitness Research found that subjects who trained with kettlebells increased their core strength by 70 percent after an eight-week program.
Other research by experts at the American Council on Exercise (ACE) has found that kettlebell training also increases aerobic capacity – protecting lung and heart health – and improves balance.