It was hard to keep track of all the superheroes hitting the big screen this summer: Batman in "The Dark Knight Rises." Iron Man, The Hulk, Captain America and Thor in "The Avengers." Peter Parker in "The Amazing Spider-Man."

And each character seemed to have bulked up for their latest comeback.

"Over the last few decades, superheroes' bodies have become extremely muscular with body dimensions that are impossible for most men to attain," write the authors of a new study that analyzes the effects of superheroes on male body image.

Past research has shown that seeing muscular figures can make men feel badly about their own bodies, similar to the way seeing stick-thin supermodels can make women question their weight.

But the same effect may not hold true for our favorite comic book characters.

The study, published this week in the Journal of Experimental Social Psychology, suggests watching superheroes can actually increase males' self esteem - and might make mere mortals stronger.

The study

Researchers with the University at Buffalo asked 98 undergraduate males to rate how much they liked and/or were familiar with Batman or Spider-Man on a scale of 1 to 5. Participants who scored a 4 or higher were said to have a "parasocial" relationship with the superhero - i.e. a one-sided psychological bond. Those who rated less than 2.5 were put into a control group.

All participants were then shown a photo of either a scrawny or buff-looking Batman/Spider-Man. They were given one minute to look at the photo and then asked to rate their mood, self-esteem and body esteem (how they perceive their muscular strength, biceps, etc.)

The undergrads were then tested with a hand-held dynamometer to assess their physical strength.

The results

Participants who had a strong parasocial bond and were shown a muscular superhero photo recorded higher body esteem than those who didn't have a bond with the character.

On the flip side, participants who weren't familiar with the character who were shown a muscular photo experienced a lower body esteem than participants who were shown a scrawny superhero.

More surprising were the strength test results. The undergrads with a parasocial bond who were shown a muscular superhero were stronger than those in the control group and stronger than those with a parasocial bond who were shown a non-muscular photo.

The takeaway

"The thing that I find most interesting ... is the idea that these media figures have real psychological effects on the self," says study author Ariana Young, a doctoral candidate in psychology at the University at Buffalo. "It’s not just mind-numbing entertainment. The bonds that we form –- and we do form real bonds - they affect how we feel about ourselves. And it’s not always in a bad way."

Young is planning another superhero study this semester where she'll analyze the effects of the characters on acts of heroism, or helpful behavior.