Boost Energy & Mood: Find Your Spring
- When humans hop at high speeds, a counterintuitive process occurs in the calf muscles, according to researchers at the University of Tokyo.
- Daisuke Takeshita, an associate professor, and Kazuki Kuriyama, a doctoral student in the Department of Life Sciences, studied how muscles and tendons cooperate during bouncing movements.Hopping served as...
- Takeshita said human movements, such as hopping and running, are frequently enough characterized by a spring-mass model.He added that the leg acts as a spring supporting the body...
Uncover teh secrets of human movement! University of Tokyo researchers have discovered a captivating “negative stiffness” mechanism in calf muscles that enhances leg function and athletic performance. They found that key muscle fibers shorten during high-speed hopping, making legs stiffer for faster motion. This research, highlighted by News Directory 3, could revolutionize athletic training, rehabilitation, and even prosthetic design. Their work explores how the leg acts as a spring, impacting how we understand muscle-tendon dynamics. learn how this biomechanical breakthrough could change the future of sports science and medicine. Discover what’s next …
Tokyo Researchers Discover Leg Muscle adaptation for Speed
updated June 28, 2025
When humans hop at high speeds, a counterintuitive process occurs in the calf muscles, according to researchers at the University of Tokyo. key muscle fibers shorten, rather than lengthen, as force increases. This “negative stiffness” helps the leg become stiffer,allowing for faster motion and improved athletic performance.
Daisuke Takeshita, an associate professor, and Kazuki Kuriyama, a doctoral student in the Department of Life Sciences, studied how muscles and tendons cooperate during bouncing movements.Hopping served as a model for common activities like running. Their muscle-tendon dynamics research could lead to advancements in training,rehabilitation,and even the creation of prosthetic limbs or robotic exoskeletons.
Takeshita said human movements, such as hopping and running, are frequently enough characterized by a spring-mass model.He added that the leg acts as a spring supporting the body mass as it bounces off the ground. The study examined hopping under constrained conditions, instructing participants to maintain extended knees and minimize ground contact time. These constraints isolated the role of ankle joint mechanics.
Kuriyama said their findings provide a new framework for understanding muscle function during various activities. He added that rather than viewing muscles as simply generators of force, they actively modulate the mechanical properties of the leg through their dynamic interaction with tendons. This perspective opens new avenues for research in sports science, rehabilitation medicine, and biomechanical engineering.
The researchers integrated ultrasound imaging with motion capture and force plate data to understand the sequence of events unfolding beneath the skin. Takeshita noted that the ultrasound imaging portion was notably demanding. Kuriyama manually digitized the muscle fiber data from thousands of ultrasound frames, a time-consuming process requiring meticulous attention to detail.
What’s next
Takeshita and Kuriyama plan to expand their research from the lab to the running track. this will allow them to study how lower leg muscles propel athletes forward, perhaps informing more effective training and rehabilitation techniques. This biomechanical principles research aims to bridge the gap between simplified laboratory tasks and complex, real-world movements.