Courtesy Eric Sahrmann/Alter

These eye-catching images of super strong babies might make you believe the tiny tots had eaten plenty of Wheaties, or perhaps Popeye's spinach or maybe they overloaded on mother's milk in order to gain such strength.

But really, the little ones' abilities to do pint-sized push-ups, high-flying karate kicks and shirt-busting bicep curls are just the handy work of photographer Eric Sahrmann and retoucher Abe Finkelstein of ALTER, an agency that produces striking imagery for print, broadcast and interactive media.

The super-human baby photos were created as part of an advertising campaign called "strong baby" for the Milwaukee Health Department advocating healthier behaviors by young mothers to lower the city's infant mortality rate.

But wrangling the babies for the photo shoot was no easy feat.

"The most difficult was the karate baby," Sahrmann, 36, of Chicago, told GoodMorningAmerica.com. "As we had it sketched out, the baby was yelling like he was doing a huge karate kick. And I was thinking, 'How the hell are we going to get this?' We tried to digitally morph the baby's mouth and it just wasn't working. It got down to the wire."

"But then suddenly," he added, "This baby let out this huge yawn and boom, I was able to capture that real quick. We were able to get the eyes scrunching up and the mouth wide open, and it ended up being perfect."

An interesting fact about the babies in the photos, however, is that it's not just one baby.

"It's a big puzzle. No baby is one real baby," Sahrmann explained. "We had a casting for babies between the ages of 3 months and one and half years old. We ended up getting about 30 babies and parents come to the casting. It was a loud and crazy day."

He chose 10 babies to be used for each of the three photos, individually shooting each one and then digitally merging them together to form the finalized image. Each finished piece consisted of about 15 separate photographs composited together.

The younger babies, around 6-months, were used to compile the faces, and the older children, around a year old, were used to compile the bodies because they had more muscle mass.

But the work didn't end there. With all the squirming children on his hands, Sahrmann hired a professional "baby wrangler" to hold the babies into the positions he needed to composite the final photographs.

"The shooting days were just insane," he said. "You've got these little 6-month-old babies running around. The poor baby wrangler was probably exhausted by the end of the shoot."

All their hard work paid off, however. The ad campaign was very successful, even earning a prestigious CLIO Healthcare award.