14 DAY TRIAL // A new study supported by the US National Science Foundation (NSF) reveals that the secret to understanding the way frogs jump is looking at their tendons. Scientists at the Brown University were recently able to figure this out by filming the amphibians in slow-motion.
The video clips the team used for the research were filmed at around 500 frames per second, in X-ray wavelengths. Experts were able to determine that the frogs' tendons behaved in an unexpected manner just before and during the actual jumps.
For example, just before the leap is made, frogs tend to stretch their tendons all the way. Then, as their feet leave the ground, the tendons contract strongly, in a manner similar to that of a spring. Scientists say that this mechanism may be widespread in the animal world.
The investigation was prompted by the fact that frogs appear to be capable of jumping several times farther than their physiology would indicate as possible. That would be the equivalent of a person covering tens of feet in a single jump.
According to Brown University frog jumping biomechanics specialist Henry Astley, “muscles alone couldn’t produce jumps that good” in the amphibians. This line of reasoning led the scientist to conduct the new investigation in such detail.
Together with Brown associate professor of biology Thomas Roberts, Astley published the results of the research in the latest issue of the esteemed scientific journal Biology Letters. In the paper, they explain the exact mechanism they observe in frogs' feet.
The most important aspect is that leg muscles contract strongly just before the jump. This loads adjacent tendons with tension, stretching them all the way. When the muscle lets go, the tendons snap back to their original shape, releasing the large amount of energy they had previously stored.
Even when considering the frogs' feet account for nearly a fourth of their total weight, there would be no way for the amphibians to leap so far without aid from their specialized tendons. “In order to get truly exceptional jumping performance, you need some sort of elastic structure,” Astley explains.
“It’s the first time we’ve really gotten the inner workings, that we’ve put all the pieces (to frog jumping) together. We now have a clearer idea what’s going on,” adds the investigator, who is a graduate student in Roberts' lab at Brown.
“Frogs are interesting in their own right, but we are also confident that this study gives us insight into how muscles and tendons work together in animal movement. Other studies have presented evidence for an elastic mechanism, but Henry's gives us the first glimpse of how it actually works,” Roberts says.