Written by: Marc Surdyka
Training load has been defined as the cumulative amount of stress (physiological, psychological, or mechanical) placed on an individual from a single or multiple training sessions over a period of time.30Since it is a modifiable risk factor, the monitoring or management of this load has become an increasingly popular topic of discussion in recent times due to its potential utility in reducing the likelihood of injury and optimizing performance in athletes.
As alluded to above, training load is a multifactorial variable generally constituted as an athlete’s internal response (internal load) to an external stimulus (external load). Examples of external load include pitches thrown, minutes played, and distance run. Internal load may be assessed subjectively or objectively by using measures such as session rating of perceived exertion (sRPE) and heart rate.30
Now, thanks to the research of Tim Gabbett and others looking at team based sports, Gabbett was able to identify a “sweet spot” of relative loading that would help to limit the negative consequences of training while maximizing positive adaptations.15However, these findings are suggested to be used as a guideline because of the multifactorial determinants of both performance and injury, including the unique characteristics of each individual.14,37
What is meant by that? Well, although external load is an important component of the overall equation, the athlete’s perceptual or physiological response to that stimuli (internal load) may be a better predictor for injury. Indeed, a recent systematic review by Eckard et al found the strongest evidence for an association between training load and injury included the monitoring of sRPE.10This may come as less of a surprise when looking at other aspects of the research that demonstrate how factors such as psychosocial stress, lack of sleep, and anxiety may increase the overall risk for injury.18,21,25,32,35 The figure below by Gabbett depicts how these different variables might be examined in relationship to one another to make the best determination as to whether or not the athlete is prepared to train or play their sport.14
How does any of this relate to those in the workplace? Well, I think it’s a useful model to adapt to individuals who are not competitive athletes. For example, most low back pain (LBP) is unrelated to specific identifiable spinal abnormalities, yet patients are often given black-and-white diagnostic labels that exclude the multifactorial nature of their condition.3,28Since exposure to healthcare can sometimes have harmful or iatrogenic consequences, how can we as healthcare practitioners provide an environment that fosters the inclusion of all loads without using a reductionist viewpoint?24,28I think it begins with challenging our biases and often examining many of our intuitive thought processes to help hone our clinical decision making skills.7
This section will undoubtedly be interpreted by some to mean that I completely disregard the role of biomechanical stressors during sitting and other static postures, but that is not the case. Rather, I believe the experience of pain associated with something such as sitting is more likely related to inactivity, the context of the position, and the individual’s interaction with the environment (discussed more later). I am on board with temporary modifications and strategies to minimize discomfort associated with a certain position or posture, but I would like to discuss how its link to pain in the traditional sense is rather poor based on the current literature.
A common orthopaedic examination in the outpatient physical therapy setting will include the assessment of an individual’s standing and/or sitting posture. While the external load in these positions may have a small role in the overall clinical picture, it is only a single component of a much more complex process (refer back to the figure above for monitoring training load in athletes).
For one, there is evidence to show that greater degrees of thoracic kyphosis doesn’t increase the likelihood of shoulder pain, back pain, or back disability.1,12Furthermore, cervical spine alignment changes are normal with aging, there is no association between the sagittal plane curvature of the neck and pain, and the research doesn’t seem to support the idea of “text neck”.4,5,8,16What might be most disconcerting is that our clinical assessment of a person’s standing lumbar lordosis differs significantly from the range of motion they actually exhibit throughout the day.9Individuals with and without LBP also have variable standing postures during repeated bouts, and don’t differ significantly with respect to their pelvic tilt angle and amount of lumbar lordosis.19,27
The body does not differentiate between “good” load and “bad” load. If it can adapt to the high external loads placed upon it during sporting activities, it should be able to adapt to the low external loads placed upon it during sitting. However, a person’s perceptual response to that external stimuli (bringing it back to internal load) may largely be dictated by their beliefs and other non-physical factors (stress at work, anxiety during final exams, lack of sleep from a deadline, etc.). Therefore, what we say can have large implications on what patients feel. Posture must be considered within the context of the bigger picture.
Along the same lines, how do ergonomic interventions play a role in the prevention of work-related musculoskeletal disorders and pain? An overview of systematic reviews by Sowah et al found evidence of no effectiveness for interventions such as foot orthoses and shoe insoles, lumbar support (back belts, braces, chair back rests), workplace or task modifications, and education (about anatomy, effective lifting and handling technique, potential causes for LBP) in reducing episodes, prevalence, or severity of LBP. On the other hand, moderate quality evidence was found for the effectiveness of exercise or exercise and education in the reduction of LBP occurrence and recurrence.31
A Cochrane review reported moderate-quality evidence that the use of arm support with alternative mouse designs (mouse with neutral forearm posture or track ball) may reduce the incidence of neck/shoulder disorders. There was little evidence to support the use of any other interventions.34
Both studies illustrate the difficulty with attempting to prevent the onset of low back, neck, or shoulder pain with the utilization of various standalone interventions. Additionally, the interventions studied were arguably implemented to primarily address any biomechanical associations to pain. However, a large prospective study of 3,020 workers at Boeing by Bigos et al found that the strongest indicators for risk of injury were previous reports of similar problems, job dissatisfaction, and psychological distress.2Once again, I think this highlights the multifaceted nature of pain, especially in the workplace. If we’re to manage all loads, psychological stressors must be considered as well.
A systematic review and meta-analysis by Walburn et al in 2009 found that stress, broadly defined as psychological stress and negative emotional experiences, was associated with impaired wound healing.36Clearly, the non-physical affects the physical. But, as McEwen put so well, “our concept of stress is very subjective and does not take into account the enormous individual differences that exist in coping with the environment”.24Therefore, adaptations to stress will vary widely as it is thought to be the result of interactive and emergent processes.11
Stress can come in several forms. Daily hassles occur frequently like work deadlines and caregiving for a child. Life events happen less often, are more impactful, and relate to things such as getting into a car accident or being laid off. Chronic stressors last longer than 6 months and are seen as demanding, distressing, and ongoing (paying off student loans). Once more, though, the context of these stressors and our level of resources, social support, physical activity, beliefs, etc. will impact how we respond.11
The graph below by Epel et al depicts possible maladaptive responses (unhealthy) to stress compared to normal responses (healthy). Negative expectations, rumination, and hypervigilance may contribute to anticipatory reactions, poor recovery, and lack of habituation prior to, during, or following an event.11To me, it sounds very similar to patients experiencing pain who are significantly impacted by maladaptive cognitions or behaviors like fear avoidance beliefs, catasrophization, and guarding or bracing secondary to hypervigilance.33At this point, I’m hoping it starts to sound like all loads affect all aspects of the biopsychosocial model of care.
How can we put this all together using something like LBP, the leading cause of disability worldwide, as an example?17It starts with our narrative and our hypothesis, rather than diagnosis.28Even when we screen for red flags to ensure a person is appropriate for physical therapy, we can never completely rule out more sinister pathology. Just like science, what may be true about a patient presentation one day may be completely different a week or month down the line. Our thought processes and treatment strategies must evolve with our interactions with the patient and emerging data presented.
In the case of LBP, it has a lifetime prevalence of 84% and recurrence of at least 55%.33Not only do these numbers show that prevalence and recurrence are high, but also quite common. Perhaps we would do well providing reassurance to patients with LBP that it can be a normal part of life, similar to the common cold, and encourage them to continue with usual activities including work as it often gets better with time.3,13
Now, I am not arguing that we discontinue managing or treating individuals experiencing LBP. Instead, I think we need to support the recovery process by promoting the idea that the body usually has the capacity for self-healing, normalizing pain, and discussing the unique and multifactorial experience that it is.20Management of symptoms is often separated into its perceived constituent parts, but it should be tailored to reflect the many factors that coexist and interact in a non linear fashion based on the context of that person.22
Back To Load
Imagine a manual worker presents to the office with a recent onset of LBP that he attributes to not wearing his customary back brace the week prior. Obviously, we would perform a full subjective and objective assessment, but it is not farfetched to believe that he or his healthcare provider correlate his LBP with having a weak core which is why he relies on the brace. We can look at this situation differently, though.
Gabbett wrote an excellent blog (figure below) discussing how the same load management principles used for athletes can be applied outside of sport. Internal workload aside, imagine the individual in this case loading and unloading four times the number of lorries (trucks in American) than he was used to because the plant he worked for had an unusually large shipment that week.38He just so happened to forget his back brace as well.
Does that solely account for his pain? No, of course not. We cannot infer causation. But we can bring it to his attention to alter the narrative given. And if we still wanted to include some form of core exercise, it can be sold as making him more robust and resilient rather than fixing his weakness or vulnerability.26
In athletes, though, we’re also assessing the response to that external stimuli by using an evidence-based approach like sRPE. We’re likely not going to have a patient rate the difficulty of his workday throughout each week. It doesn’t mean we can’t ask questions and discuss the interactions of these various factors. We’re not trying to determine the biological cause, the psychological cause, or sociological cause – we’re trying to develop our best hypothesis about ways to influence the most important contributors to the experience of pain.
Athletes were exposed to higher injury risk when they were negatively affected by sleep, psychosocial stress, and anxiety. In the average adult, chronic pain and sleep problems are likely bidirectional in the sense that one influences the other. A study by Sivertsen et al found that the frequency and severity of insomnia, sleep onset problems, and sleep efficiency were correlated with pain sensitivity in a dose-response manner.29We also already discussed the effects of psychosocial stress and negative emotional experiences.
Load, or stress, in the physiological, psychological, or mechanical sense, doesn’t necessarily have to correlate with pain, negative experiences, or disability. Athletes intentionally apply external stimuli to induce performance enhancing adaptations. These adaptations are clearly influenced by other factors pertaining to their lives. How can we, as healthcare providers, help the general outpatient population reconceptualize LBP and other musculoskeletal conditions to instill resilient beliefs that enhance self-efficacy, hope, optimism, effective coping strategies, and a growth mindset?6
All loads matter. We don’t always know to what extent, but we can help patients explore effective means of managing the ones relevant to their condition. More importantly, we can hopefully impact future experiences of pain by empowering patients to reflect, adapt, and grow from the loads or stressors in their lives.6We’re all athletes competing with ourselves to live healthier and happier lives.