In a dramatic turn of events during a recent match against the Melbourne Storm, the Brisbane Broncos faced an unusual and challenging situation — three players suffered hamstring injuries in a single game. Among them, Adam Reynolds and Ezra Mam were injured during the same play, highlighting a common yet complex issue in sports.
Hamstring strains are the most prevalent non-contact muscle injury in running sports like rugby league. Alarmingly, statistics show that one in three athletes will experience a recurrence of this injury. The question arises: why are hamstring injuries so frequent, and what measures can be taken to prevent them?
Understanding the Hamstring Dilemma
Hamstring injuries are a significant concern for athletes across various sports. More than 80% of these injuries occur during sprinting, with others happening during stretching movements such as kicking. The most vulnerable moment is the “late swing” phase of sprinting — the instant before the foot strikes the ground when the leg is moving forward at high speed.
During this phase, the hamstrings contract while lengthening, a combination that poses a high risk of injury. The muscles are tasked with decelerating the leg and preparing it for ground contact, requiring substantial force at extended muscle lengths.
It’s not just speed that increases the risk. In the Storm-Broncos game, when Xavier Coates intercepted the ball, and Mam and Reynolds accelerated to chase him, their hamstrings were subjected to rapid stretching. This sudden acceleration can be more damaging than running at a constant high speed.
“Think of your hamstrings like a rubber band: during constant speed running the muscles stretch gradually, but yank it suddenly (as during acceleration) and it stretches faster — making it more likely to snap.”
Prevention Strategies: Sprinting and Eccentric Strength Training
While no strategy can entirely eliminate the risk of hamstring injuries, two approaches have shown promise in reducing their occurrence: sprinting and eccentric strength training. Eccentric exercises involve the muscle lengthening under tension, such as slowly lowering a weight. The Nordic hamstring exercise, in particular, has been found to reduce injuries by more than 50% when performed regularly.
This exercise subjects the hamstrings to high forces while lengthening, prompting structural and functional changes that enhance resilience. Regular sprint training also prepares the muscles for the demands of competition, offering a protective effect against injuries. However, sudden increases in sprinting load, especially after periods of inactivity, can significantly heighten injury risk.
The Importance of Consistency
Eccentric training can lengthen muscle fibers within two to three weeks by stretching existing sarcomeres, the tiny building blocks inside each muscle fiber. However, short-term changes may not offer substantial protection from injury. Longer-term training, around nine weeks, adds new sarcomeres, creating longer fibers capable of withstanding the extensive stretches involved in sprinting.
Eccentric training also enhances muscle strength by increasing their size. Stronger hamstrings can better manage the immense forces encountered during sprinting. These two changes — longer fibers and increased strength — are primary reasons why eccentric training can cut injury risk by half.
Other factors, such as quicker muscle activation and stronger tendons, might also contribute, although research in these areas remains limited.
Challenges and Solutions for Athletes and Teams
The protective effects of eccentric training are not permanent. Without ongoing training, muscle fiber length and added sarcomeres begin to regress within three weeks. This presents a significant challenge in professional sports, where busy schedules and muscle soreness from eccentric exercises can deter teams from maintaining these prevention strategies in-season.
Fortunately, muscles adapt quickly to eccentric training, reducing soreness over time. Once athletes build tolerance, just four Nordic reps per week may suffice to maintain the protective benefits without overloading them. Teams that consistently employ these exercises report fewer injuries compared to those that do not.
An Ongoing Issue in Sports
Despite advancements in sports science, hamstring injuries remain the leading cause of training and competition time loss in professional football codes. Predicting and preventing these injuries is challenging, but eccentric strength training and regular sprinting offer valuable protection.
Effective prevention requires not only the use of eccentric strength training exercises but also their consistent application, alongside careful management of load, recovery, and other risk factors. Implementing these practices in elite sports is complex, which may explain why hamstring injury rates have not significantly decreased.
As the sports community continues to seek solutions, the importance of understanding and addressing hamstring injuries cannot be overstated. With ongoing research and dedication to prevention strategies, the goal of reducing these injuries remains within reach.
