Running season is in full swing at the moment with a plethora of fun runs available, covering 10km, 21 km (half marathon) and 42.2 km (marathon). However, the motivation to run doesn’t necessarily involve competing with others, it could be for stress relief and mental health, general fitness, personal enjoyment or part of a weight loss regime. Regardless of the motivation, injury risks are associated with running where 19% to 79% of runners will experience a running related injury in a given year. Even with improvements in shoe technology helping runners run faster, the injury rates have remained reasonably unchanged since the 1970’s when the modern running shoe was first introduced.
Known risk factors related to injury risks in male and female runners include a previous history of an injury, especially in the case of muscle strains and fractures, running with insoles/inserts, and a rapid increase in distance run. There is mixed evidence that absolute high distances (consistently running high distances each week) may or may not be involved with injury risk. Overall, females have a lower injury risk than males however, additional risk factors for women include older age, a longer weekly running distance (48-64km), running on concrete and wearing running shoes for 4-6 months. Whereas males are more at risk if they are restarting running after time away, have been running for less than 2 years and run more than 64km per week. It is also well established that 80% of all running injuries are overuse, this coupled together with the known risk factors for running injuries indicates that training loads play a potential role into why runners experience high injury rates.
What does all of this mean for someone who likes running, it says that although running injuries have multiple causes managing training loads is extremely important to mitigating the risk of injury. With some evidence showing that absolute high training loads can have a protective effect on injury in certain sports, the key is to minimize acute load increases or training spikes. In simple terms this means training loads need to be consistent with small increases in load. A load based model has been put forth called the acute:chronic ratio and it essentially says that the current weeks training load should be between .8-1.3 times the load of the previous 4 weeks of training, if the load is 1.5 times or greater the risk of injury increases.
In lay terms this means if someone is running 5km 2 times per week for 4 weeks and then decides to add a third longer run of 10km a week in the 5th week, they greatly increase their risk of an injury. Does this mean pulling out the calculator to crunch the numbers to get your ratio right, not really. There are plenty of fantastic running training plans available for all levels of runners and all distances, programs that factor in gradual load increases, rest periods and tapering. Running should be enjoyable and injury free regardless of the motivation, so to reduce the risks of sustaining an overuse injury manage the load, gradually increase the kilometres run, avoid training spikes and allow for rest periods. If you do sustain an injury be sure to promptly consult an appropriately trained sports based practitioner/physician.