Injuries presenting to our Boulder Physical Therapy practice fall into two broad categories including acute, traumatic (sprains, strains, fractures) and microtrauma or overuse injuries (tendinopathy). This latter category is the most common, but may also be more preventable. Overuse injuries are created when a participant performs too much activity, too soon and the forces of exercise exceed the tissue’s capacity. Challenging a given tissue (bone, muscle, tendon) with exercise loading is an excellent way to strengthen the tissue and improve its’ capacity, but the progression must be gradual with adequate recovery periods. Conversely, if the exercise or activity is progressed quickly without adequate rest the tissue is susceptible to more breakdown than recovery (ex. stress reaction or fracture). These training errors are the most common pathway to injury in both the research and our clinical practice. Participants need to monitor their training loads to avoid this pathway and reduce their risk of developing an overuse injury.
Multiple authors have documented the training error as a common risk factors for injury and some have proposed a monitoring system to reduce this risk (Hulin et al. Br J Sp Med. 2013 and 2016. Morrison et al. 2017). Monitoring your acute (current week) and chronic (4 week average) training loads are key. Authors recommend multiplying your minutes of training by the intensity (rating of received exertion, metabolic equivalent, heart rate zone) for the week. For example a moderate run (5/10 on RPE scale) for 30 minutes would equal 150 minutes and an easy bike ride (4/10) for 120 minutes would equal 480 minutes. This minutes are then totaled for all activities for the current week and divided by the 4 week moving average for the previous weeks (acute:chronic ratio). This ratio gives the participant an objective data point for how much they are progressing their training in a given week. For example, a ratio of 1 indicates their training is on par with previous weeks, but a higher number may indicate a larger risk of injury. Authors have suggested a ratio of 1-2 indicates a progression of load (often justified but should be monitored) and a ratio of > 2 is a risk factor for injury.
Multiple technologies and programs are available for tracking your training volumes, but a simple journal and calculator would also provide the information needed. Stay fit this training season and avoid the most common pathway for injury, the training error.