Scientists Have Developed an Unpowered Exoskeleton that Reduces Metabolic Rate While Running

October 17, 2018

Want to Add a ‘Spring’ to Your Stride? For the First Time, Scientists Have Developed an Unpowered Exoskeleton that Reduces Metabolic Rate While Running

This Exciting Development Marks the Beginning of a New Era for Human Augmentation Research and Product Development

PISCATAWAY, NJ, October 17, 2018 – Groundbreaking robotics research in the emerging area of human augmentation, which focuses on wearable exoskeletons to improve the performance of the human body, is featured in the October issue of the IEEE Transactions on Neural Systems and Rehabilitation Engineering (TNSRE), a journal published by the IEEE Engineering in Medicine and Biology Society. In recent years, there has been some progress made in reducing the metabolic rate of walking and running, but developing exoskeletons that are lightweight, easy to wear, that also offer reliable, long-lasting power sources has remained elusive. A team of Iranian biomedical engineers has now, for the first time, developed an unpowered exoskeleton that reduces metabolic rate while running.

The research team is led by Rezvan Nasiri, and includes Arjang Ahmadi, and Majid Nili Ahmadabadi, all from the Cognitive Systems Laboratory, Control and Intelligent Processing Center of Excellence at the School of Electrical and Computer Engineering at the University of Tehran, in Iran.

“The exoskeleton we developed reduces the metabolic rate by 8% during running by using a rotational spring system which couples two hips in the sagittal plane. The device takes advantage of the ‘scissor kick’ motion that occurs naturally during running – the reciprocal motion of the body recycles that energy, thereby allowing us to create an unpowered exoskeleton. No external battery is required, making the device lightweight and unobtrusive,” said lead researcher, Rezvan Nasiri. “Users do not need to run at a constant speed to achieve metabolic rate reduction. We look forward to testing our device under a wide variety of settings in our future work.”

The exoskeleton the team developed was tested on ten healthy active subjects for running at 2.5 meters per second. The team repeatedly achieved 8% metabolic rate reduction when compared to the subjects running at the same speed without wearing an exoskeleton. The exoskeleton is entirely human powered, and does not have any motors, electrical systems, or sensors. The research team project that by reducing the mass of their device, up to 10%, metabolic rate reduction is possible, which is an extremely exciting prospect in the field of human augmentation, and for anyone interested in recreational running. The Iranian team’s work was supported by the University of Tehran.

“This new research is special because it has been incredibly hard to reduce energy costs of a physically intact human by adding a device to their legs. Achieving this is a tremendous breakthrough in the field of human augmentation because humans are so incredibly good at minimizing metabolic energy cost during locomotion. Until now, no one has been able to add a device to humans that could reduce that metabolic energy expenditure for running,” said Dr. Rodger Kram, Associate Professor Emeritus of Integrative Physiology at the University of Colorado, Boulder. An expert in the energetics of running, Dr. Kram continued, “the beauty of this new device really lies in its simplicity – at less than 2 kilograms, it is lightweight, and requires no external power. It is portable, quiet, and not at all bulky. I’m impressed by this team’s achievement, which has big implications for the running industry. It will be exciting to follow the innovations that result from their work.”

“This team has developed a very simple, elegant solution that integrates almost seamlessly into the body’s natural movement. Humans have evolved the ability to run over millions of years, and we’re super efficient at it. This makes it especially difficult to improve the function of the already ‘tuned’ biological system – and doing so has long been a challenge for scientists and engineers,” said Dr. Greg Sawicki, an Associate Professor of Mechanical Engineering and Biological Sciences at Georgia Tech, and head of the Human Physiology of Wearable Robotics Lab. “The team in Iran has found a way to remap the structure of the musculoskeletal system with little more than a spring, essentially giving runners the equivalent of a new body part and an alternative pathway for exchanging energy. Their research has tremendous implications for our field, and I’m excited to see what develops as a result of this trailblazing work.”

The entire paper which describes this new research will be available tomorrow on the IEEE TNSRE website,


Via its website,, the IEEE Transactions on Neural Systems and Rehabilitation Engineering (IEEE TNSRE) journal publishes cutting-edge research on the rehabilitative and neural aspects of biomedical engineering, including functional electrical stimulation, acoustic dynamics, human performance measurement and analysis, nerve stimulation, electromyography, motor control and stimulation, and hardware and software applications for rehabilitation engineering and assistive devices. The journal has an impact factor of 3.972. The papers published in IEEE TNSRE are accessible through IEEE Xplore. Researchers are invited to submit papers with their research findings and clinical translation studies for publication in the journal.

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