Balancing Act: Biologist Laura Guss Researches the Biomechanics of Head Load Carriage in the Women of Sub Saharan Africa

Women and young girls in Zambia and remote locations around the world trek miles each day carrying heavy loads of water, food and other necessities. Not with their arms, but on top of their heads.

You’ve likely seen videos and photographs of this incredible display of balance and wondered, how do they do that?

It seems so effortless.

“The women of sub-Sahara Africa often don’t use their hands at all,” explained Radford University Associate Professor of Biology and evolutionary biologist Laura Gruss. “They are very good at it.”

They have to be good; their families and communities depend on their steady and consistent work.

Over the course of a couple of million years, Gruss explained, “Carrying has been an integral part of being human. People go out and hunt for food, pick berries or dig up roots, gather firewood and take it back to share with everybody else.”

For years, women and girls as “young as 6, 7 or 8 years old,” Gruss noted, have carried much of the responsibility.

Many of the women do more than carry heavy loads – sometimes it’s around 30% of their body weight – atop their heads. Often, they have a baby on board, too, strapped to their backs.

Gruss and a couple of research colleagues – one from the University of Massachusetts and the other from Seattle Pacific University – have a particular interest in studying the efficiency of these female load carriers, the biomechanics of head load carriage and the impact and toll the loads can place on the human body.

“We want to study changes in the movements and energetic efficiency of walking with a load on the head and carrying a load on the head while also carrying a baby, which is also very common,” Gruss said. “Not many studies have looked at how movement actually changes when a woman is carrying a load on her head, and no one has ever looked at the kinematics of carrying a load while also carrying an infant.”

Gruss and her colleagues also plan to examine how carrying these heavy loads can change a woman’s biomechanics when walking with other people since women typically walk together, which can affect walking speed and mechanics.

“We don’t always get to choose how fast or slow we walk, which means that we are not always walking at our most efficient,” Gruss noted. “Look around anytime and anywhere, and you’re usually going to see people walking with someone else, especially if they have children.”

To get started, Gruss and Radford students began a pilot study in the fall 2023 semester with hopes of securing a National Science Foundation (NSF) grant to purchase necessary research equipment and fund a trip to Zambia for her and two students to do further research.

Inside the Center for the Sciences biology labs, students practiced walking with a 10-liter bucket of water on their heads. Gruss allowed them to use their hands to steady the heavy load. They also walked, with and without the buckets, alongside a partner. Students videoed the walks and collected data measurements to determine how head load carriage affects speed, walking stride and energy consumption.

“If there is extra energy being used on carrying water,” said Angelina Walters, a senior anthropological sciences major from Winchester, Virginia, “it can take away energy needed for growth and repairing the body” from the physical exertion.

The work may “allow us to help prevent injuries of people who carry heavy loads each day,” added student researcher George Copeland of Salem, Virginia.

While the students are busy with work that may improve the lives of others, they, too, are reaping longterm rewards from the research.

“It is very important to me that Radford offers such impactful research opportunities for undergraduate students,” Walters said. “As a fourth-year research student, I feel prepared and confident to understand research processes, present research and collaborate on projects.

“These opportunities,” she continued, “have helped shape my undergraduate career and have helped prepare me to move on to further education and long-term careers.”

The data being collected will go a long way toward furthering the research by applying for the NSF grant that will help pay for a trip to Zambia in 2025 and a cameraless equipment system that can accurately measure each the location, angular momentum and position of subjects’ body segments.

“We are hoping that by documenting the biomechanics of head load carriage, it could help advise health policy,” Gruss said. “The girls can’t simply stop their responsibilities to the families and communities, but if we can gather and introduce better information out into the public – about how this affects women and young girls –then better and more informed healthcare policies can be made to protect them.”