Why the Nordic hamstring exercise protects against injury

Training helps hamstring muscles produce force at longer lengths without overstretching muscle fibers

Journal of Sport and Health Science

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Adaptations in the hamstring muscle-tendon unit following a 9-week eccentric training program. The results demonstrate that while training allows muscle fibers to operate over significantly longer active lengths (top right), the estimated active sarcomere lengths remain near their optimal range for force production (bottom right). This suggests that the muscle adapts to the high demands of the Nordic hamstring exercise by increasing serial sarcomere number, effectively allowing the muscle to reach greater lengths without overstretching its individual functional units.

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Credit: Dr. Max Andrews from The University of Queensland Image Source Link: https://doi.org/10.1016/j.jshs.2026.101134

Hamstring injuries are among the most common injuries in sports, particularly in activities involving sprinting and rapid acceleration. They account for roughly 10% of injuries in field-based sports and often result in significant time away from competition. Despite their frequency, the mechanisms underlying the effectiveness of certain training programs in preventing these injuries remain poorly understood.

Researchers from The University of Queensland and the University of Southern Queensland, in collaboration with Stanford University, investigated how nine weeks of Nordic hamstring exercise training affects the hamstring muscle function. Published in the Journal of Sport and Health Science on March 19, 2026, the study examined how this widely used injury-prevention exercise alters the mechanics of the biceps femoris long head—the hamstring muscle most commonly injured during sprinting.

“Previous research has shown that exercises such as the Nordic hamstring exercise are very effective at reducing hamstring injury risk,” said first author Dr. Max Andrews, who conducted the study as a visiting researcher at Stanford and is now a postdoctoral fellow at The University of Queensland. “These exercises target the lengthening phase of muscle contraction and are known to increase eccentric strength and muscle fascicle length. However, we still don’t fully understand how these structural adaptations alter the muscle mechanics during exercise to produce this protective effect, which is what motivated this study.”

To investigate these changes, the researchers had participants complete nine weeks of supervised Nordic hamstring exercise training. During the training, researchers measured hamstring strength and used ultrasound imaging to track the behavior of muscle fibers, while motion capture was used to estimate changes in the length of the entire muscle–tendon unit. The researchers also estimated sarcomere lengths—the microscopic contractile units responsible for producing muscle force—by combining fascicle length measurements obtained during the exercise with previously measured serial sarcomere numbers.

After nine weeks of training, eccentric knee flexor strength increased by about 40%, allowing participants to control the Nordic hamstring exercise through a greater range of motion. During the exercise, after training participants could lean further before reaching peak force. As a result, the hamstring muscle–tendon unit reached longer lengths during the movement, while the muscle fibers themselves reached lengths about 25% greater than before training. Despite these longer fiber lengths, the estimated lengths of the sarcomeres did not change.

According to the researchers, this finding is consistent with the addition of sarcomeres in series within the muscle fibers—an adaptation for which previous work from the same group has provided evidence. By adding sarcomeres end-to-end, muscle fibers become longer while each individual sarcomere continues to operate near its optimal length during contraction. This structural adaptation allows the muscle to generate force effectively even when stretched to longer lengths, such as during sprinting.

“Following training, the muscle fibers can stretch to longer lengths during the exercise without overstretching the sarcomeres,” said senior author Dr. Patricio Pincheira, from the University of Southern Queensland. “This may be one reason why eccentric training is effective at reducing hamstring injury risk. By increasing fiber length through serial sarcomere addition, the hamstrings can generate high forces across a wider range of muscle lengths, which may allow them to stretch further without overstretching.”

Previous findings show that hamstring strains often occur during the late swing phase of sprinting, when the muscles lengthen rapidly while producing high forces. If muscle fibers can tolerate longer lengths without overstretching the sarcomeres, they may be better able to withstand these demands.

“One of the long-standing questions has been why the Nordic hamstring exercise is effective at reducing injury risk,” said Dr. Pincheira. “Our findings suggest that the muscle adapts in a way that allows it to generate force at longer lengths, which may help the hamstrings tolerate the large mechanical demands placed on them during dynamic movements.”

The findings help bridge the gap between laboratory measurements of muscle structure and the real-world effectiveness of hamstring injury-prevention programs. A better understanding of muscle adaptation to eccentric training could help refine exercise prescription in practice. This insight could ultimately enable coaches and clinicians to develop more targeted and effective strategies to reduce one of the most persistent injuries in sport.

 

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Reference
DOI: 10.1016/j.jshs.2026.101134

About The University of Queensland
The University of Queensland (UQ) is a leading public research university in Brisbane, Australia, founded in 1909. A member of the prestigious Group of Eight, it is globally recognized for excellence in teaching, research, and innovation. UQ offers diverse programs across science, engineering, medicine, business, and the humanities. Its strong research output includes contributions to major medical and technological advancements. With a vibrant international student community and world-class campuses, UQ plays a key role in shaping global knowledge and future leaders.
Website: https://www.uq.edu.au/

About Dr. Max H. Andrews from The University of Queensland
Dr. Max H. Andrews is a Postdoctoral Research Fellow in the School of Human Movement and Nutrition Sciences at The University of Queensland (UQ), Brisbane, Australia. His research focuses on muscle physiology, particularly how eccentric training influences muscle structure and helps prevent hamstring injuries. He completed his PhD at UQ, where he developed expertise in advanced imaging and neuromuscular assessment techniques. Dr Andrews’ work aims to bridge laboratory findings with real-world sports performance, contributing to improved injury prevention strategies and athlete care.

Funding information
This work was supported by the Australian Research Council Discovery Project (DP200101476), Stanford Graduate Fellowship, The University of Queensland Graduate Scholarship, National Health and Medical Research Council of Australia Fellowship (#1194937), and Wu Tsai Human Performance Alliance at Stanford University and the Joe and Clara Tsai Foundation.

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Journal

Journal of Sport and Health Science

DOI

10.1016/j.jshs.2026.101134 

Method of Research

Experimental study

Subject of Research

People

Article Title

Adaptations in biceps femoris long-head muscle-tendon mechanics during the Nordic hamstring exercise in response to 9 weeks of training

 

Saving water, generating energy and making tomato cultivation more sustainable at the same time

The method involves planting tomatoes beneath solar panels, taking advantage of the benefits to the plant provided by the shade cast by the photovoltaic installation

University of Seville

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Sustainable production of horticultural crops based on agrivoltaic systems

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Credit: University of Seville

Researchers from the University of Seville (US) and the Polytechnic University of Madrid (UPM) have demonstrated that it is possible to grow tomatoes and generate solar energy simultaneously, a key strategy for tackling global water scarcity. The study, carried out in Madrid and Seville during the spring of 2024, evaluated the use of agrovoltaic systems and regulated deficit irrigation to optimise water resources in tomato cultivation. The results show that, although using less water reduces the volume of the harvest, the overall outcome is a more efficient and sustainable process. 

This innovative combination aims to reduce the plants’ evaporative demand through the shade provided by photovoltaic panels, enabling a more efficient use of land and water. The research compared three irrigation methods: a control group with full irrigation, a regulated deficit irrigation (RDI) system based on the plant’s water status, and an agrovoltaic (AG) system that applied the same water restriction under solar panels. The study measured variables such as leaf water potential and gas exchange to monitor plant stress at different growth stages. The results indicate that, although the shade from the panels reduces available radiation, the design of the system permits adequate plant development to be maintained at most stages of the crop cycle.

One of the most notable findings is that the deficit irrigation strategy reduced water consumption by approximately 50% compared to traditional irrigation. However, this drastic reduction in water led to a yield decrease of around 20% in the RDI treatment, attributed mainly to severe water stress conditions during the ripening phase. Despite this drop in total tomato production, irrigation water productivity increased significantly in the Seville treatments, demonstrating that more fruit can be obtained for every drop of water invested.

Furthermore, the overall success of the agrovoltaic system was validated by the Land Equivalent Ratio (LER), which combines the efficiency of agricultural and electricity production. The values obtained—1.54 in Madrid and 1.67 in Seville—confirm that combined production is far more efficient than growing tomatoes and generating energy on separate plots. This implies that, although tomato yield decreases under the panels, the system’s profitability and sustainability increase thanks to the generation of clean energy in the same space.

In conclusion, the study highlights that agrovoltaics is a promising tool for the agriculture of the future, although it requires more precise irrigation management to avoid excessive stress. The researchers suggest that combining plant measurements with soil moisture sensors could further optimise these systems. This advance points to the sustainable dual use of land, offering a viable solution to the challenges of climate change and the energy transition.

The study forms part of the Ministry of Science and Innovation and the State Research Agency’s PID2021-122772OB-I00 project, entitled ‘Sustainable vegetable production based on agrovoltaic systems’. It was led by experts from the ETSIAAB at the Polytechnic University of Madrid, CEIGRAM and the ETSIA at the University of Seville. The results are published in the prestigious scientific journal Agricultural Water Management.

 

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Journal

Agricultural Water Management

DOI

10.1016/j.agwat.2026.110281 

Article Title

Regulated deficit irrigation based on plant water status and Agrivoltaic systems as possible improvements on water resources management in tomato

 

Warmer winters and snow drought may threaten western U.S. water by speeding flows, study finds

Oregon State University

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Naches River in Washington. 

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Credit: Zach Butler, Oregon Stat University

CORVALLIS, Ore. – As future shifts in climate lead to more rain and less snow in the western United States, new research finds that water will move faster through a landscape, likely leading to negative impacts on summer water levels and water quality.

The study is especially relevant at this moment because the western United States experienced similar snow drought conditions this past winter, with generally typical precipitation amounts, but less snow because of warmer temperatures.

“This winter has been exactly like what our paper had said the future will be like,” said Zach Butler, a postdoctoral scholar at Oregon State University and lead study author, who has a part-time job forecasting winter weather in Oregon for the site OpenSnow.

The research can help inform future water management decisions. While the timing of water release relative to snowpack has long informed water planning, understanding how long it takes for water to travel through a landscape is not well understood and is important, especially at a time of increasing weather disturbances and extreme conditions.

In the new study, recently published in Scientific Reports, Butler and a team of researchers from Oregon State, Pacific Northwest National Laboratory and the National Center for Atmospheric Research in Colorado estimated “water transit times” – the time between rain or snow falling on the landscape and leaving as streamflow – will be 18% faster on average in the late century.

Faster water transit times have been shown to negatively influence water quality because during high-water events there are often spikes of contaminants that have been stored for a shorter period in shallow subsurface layers. Additionally, during low-water conditions, contaminants can be stored for a longer period of time.

The seasonal shift to faster water transit times in the winter will also likely lead to less water in streams, rivers, lakes and reservoirs in the summer, which could have negative implications for aquatic species such as salmon and trout and less water for drinking and agriculture.

The study focused on the Naches River, the main tributary of the Yakima River in Washington. The river basin is one of the most climate-sensitive basins within the Columbia River basin due to projected warming and snowpack declines, the researchers note.

Snowpack declines in the Naches River basin from 1991-2020 have already resulted in discharge peaking earlier in the spring. Other research has projected a 16% decrease in snow and a 25% increase in rain by 2036-2050.

While the researchers focused on that one basin, the framework they developed can be used to predict historical and future water transit times in other parts of the western United States and the world. Their work builds and aligns with studies conducted by other scientists in the Rocky Mountains and Europe.

The research is important because one-sixth of the world’s population relies on snowmelt water for drinking or agriculture, the researchers note. In the United States west of Colorado, 53% of water runoff originates as snowmelt.

Variability of water transit times is traditionally calculated by analyzing natural chemical tracers, such as stable water isotopes, found in precipitation and streamflow. This is costly and logistically challenging because it requires collecting water samples in the field.

Butler and scientists from the Pacific Northwest National Laboratory collected samples from the Naches River and coupled those in a novel way with an advanced hydrologic model to estimate water transit times both in the past and future.

“This study provides a crucial step in improving projections of water resource responses to climate change and underscores the value of integrating water transit time dynamics into future hydrologic assessments,” Butler said.

Co-authors of the paper are Stephen Good, Mark Raleigh and Catalina Segura, of Oregon State; Huancui Hu and Xingyuan Chen of Pacific Northwest National Laboratory; and Aubrey Dugger of the National Center for Atmospheric Research.

Good is an associate professor in the College of Agricultural Sciences and director of the interdisciplinary Water Graduate Resources Program. Raleigh is an assistant professor in the College of Earth, Ocean, and Atmospheric Sciences. Segura is a professor in the College of Forestry.

 

Zach Butler, an Oregon State University postdoctoral scholar, collecting a water sample on the Naches River in Washington.

Credit

Lupita Renteria

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Journal

Scientific Reports

DOI

10.1038/s41598-026-46539-1 

Subject of Research

Not applicable

Estonia’s first cloned foal born with the help of Estonian University of Life Sciences scientists

Estonian Research Council

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1_Cloned foal Wodan M Alpha, three days after birth.

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Credit: Estonian University of Life Sciences/Kristina Haan

The birth of the first cloned foal is the result of years of research and development, carried out in partnership between scientists at the Estonian University of Life Sciences and Luunja Stud Ltd. “The foal is strong and viable, but to protect its health, we will keep the stable under quarantine for some time,” said Elina Tsopp, embryologist at the Estonian University of Life Sciences and lead scientist of the cloning process.

The foal is a genetic copy of the former sport stallion Wodan M and has been named Wodan M Alpha. Wodan M was a successful competition horse owned by Urmas Raag and achieved notable results in sport. As a breeding stallion, he produced many high-quality offspring. “One of the aims of horse cloning is to preserve the genetics of top-performing horses. Even more importantly, cloning technology can also help conserve endangered horse breeds,” added Tsopp.

Estonia is one of the few countries in Europe working at such a high level in equine reproductive biotechnologies. It is now the second country in Europe where a cloned foal has been successfully produced, following earlier successes at the Avantea center in Italy. In 2024, scientists from the Estonian University of Life Sciences, in cooperation with Luunja and Perila stables, also achieved the birth of Estonia’s first ICSI foal, Endex. This marked an important step in the development of reproductive technologies in Estonia and provided momentum for pursuing horse cloning.

Cloned foal is the result of outstanding teamwork and fruitful international collaboration. The horse cloning research group includes Elina Tsopp, Anni Viljaste-Seera, Andres Reilent, Felipe Corrêa, and Andrès Gambini from the University of Queensland. A long-term partner of the University’s scientists is Luunja Stud Ltd, led by Sven Šois and Urmas Raag.

 

2_Mare with foal Wodan M Alpha.

 

3_Mare with foal Wodan M Alpha in stable.

4_Cloned foal Wodan M Alpha in his stable.

Credit

Estonian University of Life Sciences/Kristina Haan

Method of Research

News article

Subject of Research

Animals

 

From specialized to adaptable AI systems

André Biedenkapp receives Emmy Noether award for research on generalizability in reinforcement learning

Karlsruher Institut für Technologie (KIT)

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Dr. André Biedenkapp, winner of an Emmy Noether award from the German Research Foundation (André Biedenkapp, KIT).

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Credit: André Biedenkapp, KIT

“The Emmy Noether award helps outstanding young researchers to become academically independent at an early stage in their careers,” said Professor Stefan Hinz, Vice Provost Early Career Researchers at KIT. “His work on developing adaptive AI systems makes Dr. André Biedenkapp a prime example of an excellent young researcher at KIT.”

 

Reinforcement learning (RL) is an artificial intelligence (AI) learning paradigm in which an AI agent learns how to behave in a specific environment by trial and error. Feedback in the form of rewards helps a system to repeat desired behaviors and avoid inappropriate ones. This is an especially powerful method for problems in which decisions must be made sequentially, e.g. in robotics, logistics, or resource management. 

 

However, a key problem with traditional RL approaches is that the learned strategies often depend strongly on the training environment. Even small changes can mean that an AI agent no longer knows how to behave appropriately. “Today’s RL agents work superbly under the conditions they’ve been trained for, but they reach their limits quickly when those conditions change,” said Biedenkapp, who is working at the University of Freiburg through August 2026. From September 2026, he will be leading the newly funded DFG Emmy Noether Group “From Mediocre to Masterful Generalists: The Power of Context in RL” at KIT’s Institute for Anthropomatics and Robotics.

 

More Context for More Robust Learning Processes

The Emmy Noether Group’s goal is to extend RL training methods so that AIs become more robust and adaptable. To do so, Biedenkapp’s team will make use of additional information about the environment or world in which an agent acts. In this way, an AI can learn which behavior is best suited to which situation and then apply that knowledge to similar unknown situations later.

 

In the long term, this approach could be a key step toward increased use of RL in real-world applications. Many RL-based AI systems have thus far had to rely on very exact simulations of real environments, but the required simulators are complicated, expensive, and difficult to implement for complex scenarios. “If RL-based systems could generalize better, it would no longer be so important to simulate every possible situation perfectly. That would expand the range of possible applications for this technology considerably,” Biedenkapp said.

 

About the Emmy Noether Program

The Emmy Noether Program gives exceptionally well qualified scientists in the early phase of their career the opportunity to qualify for a university professorship by independently leading a research group over a period of six years.

 

More information

 

In close partnership with society, KIT develops solutions for urgent challenges – from climate change, energy transition and sustainable use of natural resources to artificial intelligence, sovereignty and an aging population. As The University in the Helmholtz Association, KIT unites scientific excellence from insight to application-driven research under one roof – and is thus in a unique position to drive this transformation. As a University of Excellence, KIT offers its more than 10,000 employees and 22,800 students outstanding opportunities to shape a sustainable and resilient future. KIT – Science for Impact.