Monitoring Training Load for Runners
Why We Run
Running has been and continues to be a popular form of exercise due to its easy accessibility and minimal need for equipment. With gyms closing and social distancing during the pandemic, there is a good chance you and someone you know has taken up running as part of their exercise routine. Long distance competitions ranging from the 5K to ultramarathons attract many runners and motivate them to keep pushing themselves to the next level. However, with longer distances comes the risk of being injured. So, how should recreational runners go about measuring and monitoring their training load to reduce risk of injury?
Measuring Training Load
In distance running, mileage per week remains the primary measuring tool to assess training load. While this is an objective measurement, it does not show the whole picture. An article written in 2020 from the Journal of Orthopaedic and Sports Physical Therapy recommends that both extrinsic factors and intrinsic factors should be assessed when measuring training load and the stress it can have on the body. Extrinsic factors include the physical work being performed, which can be measured by distance, pace, or time. Intrinsic factors are physiological/psychological responses like heart rate or rate of perceived exertion (RPE).
Rate of Perceived Exertion (RPE)
Tracking RPE is a valuable tool in assessing training load as it considers how the runner is feeling that day, which can be affected by daily factors such as stress, sleep, or diet. The RPE scale is rated from 1-10 with 1 being minimal exertion and 10 being maximal exertion.
A study done by Gabett published in the British Journal of Sports Medicine suggests using a formula that combines training time and RPE to give you a numerical value for weekly training load:
Training Time (minutes) x Average RPE score = Arbitrary Units or “Exertion Minutes”
Example: 100 minutes of training x 5 RPE score = 500 Exertion minutes
In addition, Acute vs. Chronic training load should also be tracked to give a short term and long-term picture of training. To do so, you can use the equation:
Average training load score (AUs) of last 4 week ÷ Training load (AUs) of current week
This will give you an Acute to Chronic training load ratio. We will talk more about that down below.
Monitoring Training Load to Reduce Risk of Injury
Injury happens when the tissue is pushed past the capacity it can handle. Sudden increases or changes in intensity of physical activity can potentially lead to an injury. The rule of thumb has been to not increase training load by more than 10% each week to allow for proper adaptations, though this varies between individuals and their level of experience. Novice runners are more at risk of injury; thus, they should take more caution when increasing their intensity of workouts. In addition, high weekly mileage is associated with a greater likelihood of getting injured. If you feel an injury coming on, try reducing the number of miles or duration of time you are running to allow tissues to recover.
However, gradually increasing your distance per week still may not prevent injury if you are not addressing other factors such as your sleep and mental health. A study done this year by the Journal of Sports Science and Medicine took a survey that found 54% of recreational runners reported running related injuries (RRIs) within a six-month period. Poor sleep quality and mental aspects were associated with RRIs.
This is where tracking your exertion minutes (RPE x duration) and ratio for chronic vs. acute loads comes into play. Gabbett found that ratios of 0.8 – 1.3 are the sweet spot for decreasing risk of re-injury. Any ration above 1.3 increases risk of injury. Exertional minutes could also be used to make sure the training load is gradually increasing each week.
What If The Same Run Feels More Difficult?
If you find that your RPE is higher than usual for the same distance or pace, you will want to assess what other factors are affecting your performance. You will also need to modify your training program temporarily to reduce risk of injury. Fatigue can not only make the run seem harder but can also lead to compensations and less efficient running. This in turn can lead to more stress on the tissues and increased risk of injury.
There are many factors that can contribute to running injuries, but utilizing duration and RPE to track training load, gradually progressing intensity, and modifying workouts accordingly will improve your ability to stay injury free. It can also improve your performance, but we will save that for another blog!
And remember, it is always best to address injuries sooner than later for a faster recovery. If you have been experiencing any discomfort with running, physical therapy can help.
Renae DiBartolomeo
PT, DPT, CSCS
References
Gabbett TJ. The training—injury prevention paradox: should athletes be training smarter and harder? British Journal of Sports Medicine 2016;50:273-280
Paquette M, Napier C, Willy R, Stellingwerf, T. Moving Beyond Weekly “Distance”: Optimizing Quantification of Training Loads in Runners. Journal of Orthopaedic & Sports Physical Therapy 2020 50:10, 564-569
Seyed Hamed Mousavi, Juha M Hijmans, Hooman Minoonejad, Reza Rajabi, and Johannes Zwerver. Factors Associated With Lower Limb Injuries in Recreational Runners: A Cross-sectional Survey Including Mental Aspects and Sleep Quality. Journal of Sports Science and Medicine (2021) 20, 204-215 http://www.jssm.org DOI: https://doi.org/10.52082/jssm.2021.204
