"It might revolutionize the way we treat heel pain, " says Massachusetts podiatrist Lloyd Smith, president-elect of the American Podiatric Medical Association.

FORBES: The Big Hurt

Two companies, HealthTronics Surgical Services of Marietta, Ga. and Dornier MedTech of Munich, Germany, have each gained FDA approval for shock wave machines for heel pain.

FORBES: The Big Hurt

In HealthTronics' 302-person study, for example, heel pain improved in 60% of those who got the therapy, versus 48% of those who got a fake treatment.

FORBES: The Big Hurt

More than 2 million Americans suffer from debilitating heel pain stemming from inflammation of the plantar fascia, a fibrous band of tissue that supports the arch of the foot.

FORBES: The Big Hurt

Feels like: A sharp pain in your heel (or heels) that's at its worst when you get out of bed.

CNN: Why your feet hurt

Half the cuddled babies did not show any facial expression of pain when undergoing a heel prick test.

BBC: Premature babies 'need cuddles'

O'Neill trained on Sunday, but complained of lingering pain in his left Achilles heel.

BBC: Uruguay forced into changes