In a recent match against the Melbourne Storm, the Brisbane Broncos faced an unusual and challenging situation when three of their players suffered hamstring tears in a single game. Notably, Adam Reynolds and Ezra Mam sustained their injuries during the same play. This incident highlights a recurring issue in sports, particularly in running-intensive games like rugby league, where hamstring strains are the most common non-contact muscle injuries.
Statistics show that one in three players who experience a hamstring injury are likely to suffer a recurrence. This raises critical questions: Why do these injuries occur so frequently, and what measures can be taken to prevent them?
The Mechanics Behind Hamstring Injuries
Hamstring injuries predominantly occur during high-speed activities. More than 80% of these injuries happen during sprinting, while others occur during stretching movements such as kicking. The most vulnerable phase is the “late swing” phase of sprinting, just before the foot strikes the ground. At this moment, the hamstrings are contracting while also lengthening, a combination that increases their susceptibility to injury.
It’s not just the speed that poses a risk. During the recent Storm-Broncos game, when Xavier Coates intercepted the ball, both Mam and Reynolds accelerated suddenly to chase him. This sudden acceleration stretched their hamstrings further and faster than if they had been running at a constant pace, even at higher speeds.
Think of your hamstrings like a rubber band: during constant speed running, the muscles stretch gradually, but a sudden yank (as during acceleration) can cause them to snap.
Strategies to Reduce Hamstring Injury Risk
While no approach can entirely eliminate the risk of hamstring injuries, research indicates that two methods can significantly reduce their occurrence: sprinting and eccentric strength training. Eccentric strength training involves exercises where the muscle lengthens under tension, such as slowly lowering a weight. The Nordic hamstring exercise, in particular, has been shown to reduce hamstring injuries by more than 50% when performed regularly.
This exercise subjects the hamstrings to high forces while they are lengthening, prompting structural and functional changes that enhance their resilience. Regular sprint training also helps by conditioning the muscles for the demands they face during competition. However, athletes must avoid long periods without sprinting, as a sudden increase in sprinting can heighten injury risk.
Consistency is Key
Eccentric training can lengthen muscle fibers within two to three weeks by stretching existing sarcomeres, the tiny building blocks inside each muscle fiber. However, this short-term change may not offer substantial protection against injury. Long-term training, around nine weeks, leads to the addition of new sarcomeres, creating longer fibers that better withstand the stresses of sprinting.
Additionally, eccentric training increases muscle strength by enhancing muscle size. Bigger hamstrings can better handle the significant forces encountered during sprinting. These changes—longer fibers and increased strength—are the primary reasons eccentric training can cut injury risk by half.
Challenges in Implementation
The protective benefits of eccentric training are not permanent. Muscle fiber length and added sarcomeres begin to regress within three weeks of stopping the exercises. This presents a challenge in professional sports, where busy schedules and muscle soreness from eccentric exercises can deter teams from maintaining these prevention strategies during the season.
Fortunately, muscles adapt quickly to eccentric training, and soreness diminishes over time. Once athletes develop a tolerance, just four Nordic reps per week may suffice to maintain protective benefits without overloading them. Teams that consistently incorporate these exercises report fewer injuries than those that do not.
The Ongoing Battle Against Hamstring Injuries
Despite advancements in sports science, hamstring injuries remain the leading cause of time lost from training and competition in professional football codes. Predicting and preventing these injuries continues to be a challenge. However, eccentric strength training and regular sprinting offer a protective edge.
Effective prevention requires not only the implementation of eccentric strength training exercises but also consistency, alongside careful management of load, recovery, and other risk factors. Putting these practices into action in elite sports is complex, which may explain why hamstring injury rates have not significantly decreased.
As teams strive to minimize these injuries, the focus remains on integrating scientific insights with practical applications to safeguard athletes’ health and performance.
