By Alyssa Bialowas

CrossFit has gained a lot of traction in the athletic community, especially over the past few years. CrossFit is a high intensity fitness program based on functional movements that reflect several sports and types of exercises. Overuse injuries (injury caused by repetitive trauma) are prevalent in competitive sport and are the predominant injury type in sports that have a repetitive nature and high training loads, which are both true for CrossFit.

The monitoring of heart rate variability (the variation in time between heart beats) is seen as a viable way to indicate early signs of overuse problems and substantial injury. Imbalances in the nervous system could mean the athlete is stuck in a state of ongoing repair and recovery. So can heart rate variability signify overuse problems, and can it be used to minimize overuse injury in competitive CrossFit athletes?

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The Study

Heart rate variability is a moderating factor in the workload-injury relationship of competitive CrossFit athletes. A study by Williams et al. (2017) aimed to discover whether heart rate variability can determine early signs of somatic tissue overload prior to pain or injury. They looked at the relationship between heart rate variability, workloads, and risk of overuse injuries in competitive CrossFit athletes to determine if monitoring heart rate variability can minimize the occurrence of overuse injury.

Six competitive CrossFit athletes (three males and three females) took part in the study, in which daily resting heart rate variability and workloads were recorded across a 16-week period. They were each asked to take a one-minute heart rate variability measurement when they woke up, measured by photoplethysmography (blood pressure changes in the microvascular bed of tissue) via a smartphone app called “HRV4training”.

Following that, they recorded the intensity of the previous day’s training session within the same app to measure training load. To measure overuse injury, the Oslo Sports Trauma Research Center Overuse Injury Questionnaire was sent to each athlete weekly by email. The questionnaire asked four questions that took into consideration the athlete’s knee, wrist, elbow, lower back, and shoulders.

Related Article: Crossfit For All Ages

The Results

Four out of the six athletes reported some sort of overuse problem over the course of the study, with one athlete experiencing a significant overuse problem. In two cases the overuse problem affected the knee, in two cases it affected the wrist and in two cases it affected the lower back. In one case overuse problems affected the elbow, which was also the significant overuse problem.

There was a higher risk of overuse problems when reductions in heart rate variability were in combination with workload spikes. High workloads were easily endured when heart rate variability trends were ‘normal’ or ‘high’.


Heart rate variability is a telling measurement for overuse injury in competitive CrossFit athletes. Therefore; Heart rate variability monitoring can be used to modify individual training load prescriptions to minimize overuse injury in these athletes. Heart rate variability can help determine an athlete’s psychological response to training load, and athletes that experience a reduced heart rate variation during high intensity training can benefit from recovery interventions. 

Further research would benefit from examining a wider population of competitive CrossFit athletes, as six participants is quite a small number of subjects to make any widespread claim.

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Williams, S., Booton, T., Watson, M., Rowland, D., and Altini, M. (2017). Heart Rate Variability is a Moderating Factor in the Workload-Injury Relationship of Competitive CrossFit Athletes. Journal of Sports Science and Medicine, 16: 443-449.