A paper that I started working on during the first COVID lockdown was recently published in the Journal of Sports Medicine (click here for full access). The pandemic had just hit Ontario, and I needed a project that I could work on from behind a computer screen until in-person research could resume. Retrospectively, I’m glad that I didn’t know how long it would take to complete this paper, or for life to return to a new “normal.” This paper looked at the overlap of two serious, yet common, health conditions in athletes- low energy availability and overreaching. Before explaining the results of this paper, I’ll begin with some necessary background information. 

What is low energy availability?

Energy availability represents the calories leftover for the body after accounting for the calories expended through exercise. Low energy availability occurs is when there is insufficient calories remaining for the bodies everyday processes. As a result, the body goes into “energy saving mode” and some of the bodies non-essential processes are dampened to conserve energy. This can result in reduced performance and various detrimental health outcomes, such as an increased risk of bone stress injuries. 

What is overreaching? 

Exercise is a stress on the body. For performance to be improved, the stress of training must be balanced with recovery in order for positive adaptations to occur. Too much training and not enough rest can lead to worsened performance rather than improved performance. This is known as overreaching. If not addressed, overreaching can progress into the more serious overtraining syndrome. 

Overreaching and low energy availability share overlap. The increased training that leads to overreaching also means that calorie requirements are increased. However, hunger may not increase despite the increased calorie requirements. As a result, an increased training load means not only an increased risk of overreaching, but also low energy availability. Athletes with reduced performance may be misdiagnosed with overreaching when really the reduced performance is due to undiagnosed low energy availability. Some people even believe that overreaching doesn’t really exist, and that the reduced performance seen in athletes following periods of excessive training stress is always secondary to inadequate calorie intake. In order to address this, the aim of our paper was to systematically assess the overlap of overreaching and low energy availability in published research studies. We then quantified changes in markers of low energy availability in athletes with reduced performance and changes in performance in athletes with low energy availability

We identified 56 studies that were consequently used in our meta-analysis and analysed 7 markers of low energy availability in athletes with reduced performance. Among athletes with reduced performance, some markers of low energy availability were present. This included underperforming athletes having a reduced fat mass, resting metabolic rate, and blood levels of leptin. Yet, other key indicators of low energy availability were not present in underperforming athletes. This included: body weight, and blood levels of cortisol, insulin, and testosterone. When performance was assessed in athletes with low energy availability, performance was unaffected. Several studies were also noted that showed improved performance in athletes with low energy availability. These findings highlight that while overreaching and low energy availability do share some overlap, they may also exist independently. The picture below notes the 4 different possible outcomes that were noted amongst these studies. Notably, for the middle group, we don’t know if the reduced performance was due to overreaching, low energy availability, or a combination of both.

Diagram, venn diagram

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The results of this paper highlight that both adequate rest and adequate energy intake are important for performance. A perfect diet, while important for performance, cannot make up for inadequate recovery. Athletes must not only consume enough calories, but also ensure their training plan has adequate periods of recovery if they want to perform at their best.

Categories: Megan Kuikman

Megan Kuikman

Hello! I’m Megan Kuikman. I’m a Registered Dietitian with specialized training in sports nutrition. My goal is to help athletes and active individuals achieve a healthy attitude towards health, training, and food. I empower athletes to fuel properly for training in order to restore their health and enhance performance. You can get in touch with me at: hello@megankuikmanRD.ca


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