UD cannot read this NYT article without laughing. When she gets to the middle of it —
Mr. Kelty’s solution, a modification of methods used in some earlier studies, involved a 100-centimeter-long ladder (a little over three feet) and bags of weighted pellets gently taped to the rats’ rear ends. The animals received a Froot Loop when they reached the top of the ladder and soon started climbing willingly, even without rewards. After several weeks, the climbers showed increased muscle mass, indicating that the activity was effective weight training.
— she’s practically peeing herself.