Injury prevention is an essential aspect of sports performance as it allows athletes to work at their optimal level and limit the risk of injury. Measures which are used to help prevent injury in sport can include protective equipment, warm-ups, cool-downs, and training programmes. It is vital that coaches and players have proper injury prevention methods in place, such as ensuring adequate rest and recovery periods, to minimise the risk of injuries. This is especially important as sports-related injuries can significantly impact an athlete's physical and mental well-being.
Data collection and monitoring are valuable tools that coaches can use to highlight any players at risk of injury. By tracking players' training loads, prevention methods can be implemented to reduce the risk of common injuries from occurring. Football players are reported to experience between 2.5 and 9.4 injuries per 1,000 hours of training (1). Of these injuries, over one-third are reported to be due to overuse, which means they could be predicted and therefore avoided. The high energy and impact demands of many team sports can result in different common injuries occurring, especially in football.
Many types of injuries can occur during sports and exercise, such as strains, sprains, and breaks. These can be categorised into contact and non-contact injuries. Contact injuries tend to occur by collisions with other people or objects; most injuries that occur are head injuries, quadriceps contusions, and dislocated joints. Higher-impact injuries usually include spinal injuries, ligament and tendon damage, fractures, and head and spinal injuries. Non-contact injury is a term used for when a player sustains an injury, but it is not due to being hit by an opponent, teammate, or object on the field. When a player sustains a non-contact injury, they tend to be running or standing by themselves, and then they will fall to the ground due to an injury to their body, usually their lower body.
Several non-contact injuries can arise from sports. Some examples of the most common injuries within football are ACL and Hamstring injuries. These can arise from various causes, which will be discussed in detail in our upcoming blogs.
An experimental study by Aksoy et al (6) found that 40% of all non-contact injuries were related to muscle or tendon strain, with over 66% of all injuries ruling athletes out for over four weeks. 12-33% of athletes with these injuries will experience a recurrence within a year after the initial injury (7). This shows the importance of monitoring loads to protect athletes from injury or prevent a recurrence.
This upcoming blog series will focus on injury prevention methods that coaches and players can implement for common non-contact sports injuries, and how they can be predicted through external and internal training load measures.
Training load refers to the amount of stress placed on the body during training or matches. This can be split into internal and external training loads. Internal training load represents the physiological stress imposed on the athlete in response to training. For example their heart rate and how intensely an athlete perceives a session to have been (2). These factors indicate how much energy has been used (metabolic stress) and how intensely the heart is working (cardiovascular stress). These can then be used to estimate the volume and intensity of a session along with the external load.
Meanwhile, the external load refers to the physical output performed by athletes outside of their internal responses. This can include the duration of a session, distance travelled, high-intensity runs, sprint distance and top speed. These external metrics measure the mechanical stress placed on the body and can be used to track an athlete's workload over time. Both internal and external training load monitoring is essential for an athlete's performance and can be used to track and indicate any athletes who are at risk of injury.
Previous studies have found that managing players' training loads is very beneficial for reducing the risk of injury in football among youth players(3). They reported that players with a high acute workload (short-term training load over a week) are at an increased risk of a non-contact injury. However, athletes who progressively increase their chronic workload (long-term training load, usually four weeks) can increase their tolerance to a higher acute workload over time. This can reduce the risk of injury in the long term.
Coaches can easily monitor an athlete's workload using GPS metrics from weekly and monthly reports. Focussing on absolute measures such as total distance, high intensity running distance and sprint distance, coaches can view sudden increases and decreases in workload which could lead to injury. This can be achieved by observing any unexpected spikes or dips in an athlete's training volume and intensity. Training sessions can then be adjusted for individual players so that there is an optimal balance between training and recovery. This will, in turn, reduce the risk of injury. Athletes' internal metrics can also be monitored using surveys to understand a player's RPE (rate of perceived exertion) across a series of sessions.
Both internal and external load can be used to monitor a player's workload and help with injury prevention. Firstly, the measure of total distance covered can be used by coaches to assess a player's performance and the growth of their workload. This can be achieved by recording a player's overall distance throughout a season. Additionally, it can show whether a player is at risk of burnout (4). Previous studies have found that a 15% workload increase week to week can increase the risk of injury for a player by 50% (4). For example, if a player's total distance and high-speed running is much higher for one week than usual, or expected, they should then reduce the intensity and volume of the following sessions to avoid overtraining and the risk of an injury occurring.
The same can also be observed with a top speed. When analysing a player's top speed over a season, they may have a consistent top speed but with one session potentially showing a significant spike in top speed. This large spike in top speed can also put players at risk of an injury. Previous studies have found that having a consistent top speed across a season will lower the risk of hamstring injuries in players (5). Therefore, monitoring players' session volume is vital for identifying at-risk players.
Internal metrics are also beneficial for tracking players who are at risk of injury. One method to track this is by using survey questions to assess players' rated perceived exertion (RPE) after a session. Players can rate how intense their training session was on a scale of 1 (easy) to 10 (very intense). This can then be used to create a session-RPE (sRPE). This is calculated by (session duration (mins) x RPE score). For example, if a session was 60 minutes long and rated an RPE score of 8, then the sRPE would be 480. This method of tracking internal load has been found to be valid and reliable, and can be used for sessions across a week or month to ensure players are not overtraining and at risk of injury.
Overall, monitoring athletes internal and external training load is a valuable tool in injury prevention for identifying players at risk of any non-contact injuries. In the upcoming blog posts we will give you information on what key areas of loading you should be monitoring as well as tips that can further help with preventing injury.