During this crazy year or 2 that has been 2020 and 2021, keeping up a consistent training program as been a challenge for many. Positively, a lot of us have continued training and often taken up new forms of training. As we begin to reach a new “normal”, we now have the ability to return back to previous training routines and exercises. Many of us are setting new goals, and starting to build up our training.
Once you’ve started exercising in progression towards your goals, a big consideration is ensuring you don’t increase your training load too quickly. Changes, especially spikes in activity, are linked with injury in team sport athletes and runners (Magrum & Wilder, 2010; Soligard et al., 2016). Confused? Let’s break this down…
What is load:
“The sport and non-sport burden (single or multiple physiological, psychological or mechanical stressors) as a stimulus that is applied to a human biological system (including subcellular elements, a single cell, tissues, one or multiple organ systems, or the individual). Load can be applied to the individual human biological system over varying time periods (seconds, minutes, hours to days, weeks, months and years) and with varying magnitude (ie, duration, frequency and intensity).” (Soligard et al., 2016).
Still confused? In simple, load refers to the amount of demand placed on a system. For example, this could be the amount of kilometres run, the number squat repetitions completed, the amount of time swimming, the amount of weight lifted.. and so on. Each of these activities places stress on tissues and systems of the body.
The use of loading is an important factor for improving strength, fitness, and performance (Soligard et al., 2016). As illustrated by the figure below (see figure-1), exercise load causes a short term reduction in capacity, with the body then adapting, and super-compensating to improve capacity. Subsequent bouts of activity interspersed with adequate recovery will continue to lead to increased capacity.
The next figure (see figure-2) shows how inadequate recovery and/or excessive loading can lead to maladaptation, and therefore reduced ability to accept load. This can increase the risk or susceptibility to injury.
(Soligard et al., 2016)
When broken down further, studies demonstrate that the total amount of activity (e.g. absolute load) may not be the primary problem. It has been found in a number of studies that higher activity level (training load) may actually be protective from injuries, likely due to well developed physical qualities/capacity (Drew & Purdam, 2016; Gabbett, 2016; Soligard et al., 2016). The factor more likely to increase risk of injury is the change in load, especially rapid increases in activity relative to what the athlete/individual is prepared for (Soligard et al., 2016). Periods of deloading, where there is a lack of activity, followed by a return to training, is also high risk of injury. These changes in activity are often considered “training load errors” (Drew & Purdam, 2016).
The graph above (see figure-3) demonstrates a model where there is a proposed “sweet spot” where load isn’t too high, but also isn’t too low. The model utilizes the acute chronic workload ratio (ACWR), which compares an acute period of activity/load (usually 1 week) to a chronic period of loading (usually rolling average of 4 weeks). If the ratio is between 0.8 and 1.3, this is typically the “sweet” spot where injury risk is the lowest (approximately 5% risk or less). This model, which is based upon evidence in team sports, highlights that consistent increases / maintenance of load is crucial, with a systematic progression to higher loads important to prevent fatigue/overload (and subsequent high AWCR). The model illustrates that high load (load spike) and deloading can both cause increase injury risk. Small and progressive increases in load have been recommended, with a goal of reaching high training and activity levels over time. This allows time for recovery and adaptation, where the athlete is able to increased their fitness/capacity, also avoiding periods of overload (e.g. entering the “danger zone”, see figure-3).
(Blanch & Gabbett, 2015; Gabbett, 2016; Soligard et al., 2016)
Important to note this data if from cricket fast bowlers, however the model and principle is useful to use in other settings/populations. Furthermore, the theory of not over or underloading should be utilized and adapted for most athletes/sports and individuals increase physical activity levels (Blanch & Gabbett, 2015; Gabbett, 2016; Soligard et al., 2016).
The recommendations of 10% increase in activity/load per week is often given, and has been used in some literature (Buist et al., 2008). Studies on runners show that increases above 30% per week had greater injury risk than ~20% increases (Nielsen et al., 2013). Furthermore, training load data showed that a change from <10% to >15% per week increased injury likelihood from 7.5% to 21% (Gabbet et al., 2016). Based upon this data, my recommendation would be to initially stick to changes between 10-15% per week, however individuals may vary and consultation with a physiotherapist (or other exercise & health professional should be considered).
Regular monitoring of training activity levels is important, along with assessing for potential indicators of overtraining/overload. Consider monitoring your own muscle soreness, sleep, fatigue levels, and potentially the session rate of perceived exertion (RPE) (RPE x session duration). Significant spikes in these measures are potential indications of overload, and a deload session could be recommended (Halson, 2014).
Along with injuries, studies show that high load and low load both increase the risk of illness in national level, sub-elite and recreational athletes compared to moderate loads. However, elite level athletes (e.g. medal winning) may be able to cope with high loads without the increase illness risk (Schwellnus et al., 2016) (see figure-4).
Take home messages about training load: Whilst the model (ACWR) above is complex, the messaging and methodology behind it is useful when considering your activity levels. Look to progressively increase your activity levels, avoiding periods where your current week of activity is significantly higher than your previous weeks, thus avoiding a load spike. Gradual progression, with a goal of achieving high levels of activity is recommended. Consult with a physiotherapist if you’re looking for further information and assistance.
Writing by Ky Wynne (Physiotherapist & Exercise Scientist)
This article is an excerpt from a post written by Ky Wynne: https://www.kywynne.com/post/new-years-resolutions-that-work
References:
Blanch, P., & Gabbett, T. J. (2016). Has the athlete trained enough to return to play safely? The acute: chronic workload ratio permits clinicians to quantify a player's risk of subsequent injury. Br J Sports Med, 50(8), 471-475.
Buist, I., Bredeweg, S. W., Mechelen, W. van, P., K. A., Pepping, G.-J., & Diercks, R. L. (2008). No Effect of a Graded Training Program on the Number of Running-Related Injuries in Novice Runners: A Randomized Controlled Trial. The American Journal of Sports Medicine, 36(1), 33–39.
Drew, M. K., & Purdam, C. (2016). Time to bin the term ‘overuse’injury: is ‘training load error’a more accurate term?. Br J Sports Med, 50(22), 1423-1424.
Gabbett, T. J. (2016). The training—injury prevention paradox: should athletes be training smarter and harder?. Br J Sports Med, 50(5), 273-280.
Halson, S. L. (2014). Monitoring training load to understand fatigue in athletes. Sports medicine, 44(2), 139-147.
Magrum, E., & Wilder, R. P. (2010). Evaluation of the injured runner. Clinics in sports medicine, 29(3), 331-345.
Nielsen, R. O., Cederholm, P., Buist, I., Sørensen, H., Lind, M., & Rasmussen, S. (2013). Can GPS be used to detect deleterious progression in training volume among runners?. The Journal of Strength & Conditioning Research, 27(6), 1471-1478.
Schwellnus, M., Soligard, T., Alonso, J. M., Bahr, R., Clarsen, B., Dijkstra, H. P., ... & Van Rensburg, C. J. (2016). How much is too much?(Part 2) International Olympic Committee consensus statement on load in sport and risk of illness. Br J Sports Med, 50(17), 1043-1052.
Soligard, T., Schwellnus, M., Alonso, J. M., Bahr, R., Clarsen, B., Dijkstra, H. P., ... & van Rensburg, C. J. (2016). How much is too much?(Part 1) International Olympic Committee consensus statement on load in sport and risk of injury. Br J Sports Med, 50(17), 1030-1041.
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