When the world is heavy: the impact of internal load

May 31, 2020 Borussia Dortmund’s Jadon Sancho celebrates scoring their second goal with a ‘Justice for George Floyd’ shirt, as play resumes behind closed doors following the outbreak of the coronavirus disease (COVID-19) Lars Baron/Pool via REUTERS DFL 

The NCAA reported that there were 81,096 black college athletes during the 2018-2019 academic year(1). These numbers represent 16% of the college athlete population(1). The majority of these athletes play men’s and women’s basketball and men’s football. Of course, many of these go on to play in professional sports. The number of high-school and younger black athletes is harder to quantify.

Like all athletes, black athletes are susceptible to injury. Much has been said about training load and its impact on injury occurrence. Since training errors cause the majority of sports injuries from either over or under training, getting to the sweet spot of tissue loading is paramount in sports prep and rehabilitation for all athletes(2). The emphasis is usually on the prescription of external loading – the actual physical work done via aerobic or strength training. However, the body’s internal load determines the effectiveness of the external load and the training outcome (see figure 1).

Figure 1: The training load equation(3)

Training outcomes = External load + Internal load

Various psychophysiological and social factors contribute to internal load (see figure 2).  While subjective and more difficult to measure than external loads, it influences how an athlete responds to exercise. For instance, the increased internal load from heat stress results in an athlete’s elevated heart rate. Therefore, the internal load affects elements of performance, such as speed and the volume of work. The same workout in a cooler environment would be less taxing, and thus, the athlete may be faster or stronger in lower temperatures.

Figure 2: Psychophysiological and social factors that influence internal load

  • Level of fatigue
  • Mental health
  • Mood
  • Nutrition and hydration status
  • Environment such as heat stress
  • Genetics
  • Perception of effort
  • Overall health
  • Body composition
  • Sleep
  • Stress
  • Social determinate of health

Measuring internal load

As explained previously, the response to exercise reflects the internal load. Some indicators of internal load are heart rate, heart rate recovery, and the session rate of perceived exertion. While external loads are absolute and often dictated by clinical pathways – everyone three weeks post-ACL repair performs short arc quads with 15 pounds – internal loads are individual. Higher internal loads may prevent the desired training effect from external loads. With elevated internal loads already placing stress on the body, an athlete may not complete their workout or move the needed amount of resistance to stimulate tissue healing.

Without considering an athlete’s social determinates of health and psychophysiological factors, you won’t have any idea of their internal load. Living in a post-pandemic society where athletics are on hold is stressful enough for an athlete. However, the racial injustice demonstrated in the murder of George Floyd and the resulting protests means that black athletes may carry a larger internal load. The combination of stress, worry, or lack of sleep, and the need to train without the guidance of coaches and teams, set up a perfect opportunity for injury. An athlete already in rehab under a similar internal load may have delayed healing or a slower progression along their rehab course.

Practice empathy with all patients by considering their internal load and the burdens they carry outside of the gym or clinic. Right now, the world is heavy for so many. Do what you can to lighten internal loads to produce more effective outcomes from external ones.


  2. Br J Sports Med. 2016;50:273
  3. Int J Sports Physiol Perform. 2019 Feb 1;14(2):270-273
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