For hamstring injuries, we know that if an athlete has been spending time completing a progressive Nordic hamstring program along with exercises similar to those in the FIFA 11+, he’s well on his way to reducing the risk of injury. Also, by screening for psychosocial issues we cover the centrally driven factors that may be at play.
Today we will discuss the importance of monitoring training load, something that may trump all other factors when attempting to reduce sports injuries and perhaps injuries in general. Coaches and athletes can have all the right interventions in place, but if training load is too low or too high, it may be for nothing. From the works of Dr. Tim Gabbett and colleagues, arguably, one of the best interventions and potential keys to injury reduction is monitoring off- and in-season training load using acute to chronic workload ratios (1). This ratio is created by comparing acute (weekly) amounts of work to chronic (monthly) amounts of work.
For elite level athletes, workload tracking could be captured by Global Positioning Systems, but for amateur level sport, this could be monitored by calculating “training units”: using the rate of perceived exertion (RPE) scale multiplied by the number of training minutes. Looking more closely at workload ratios and training units, recent research has shown when athletes maintain high-chronic workloads they become more resistant to injury. That is, the training acts as a vaccine to injury. Conversely, those with low chronic workloads or those who experience rapid increases in acute workload (high acute to chronic workload ratios) become more prone to injury, with one recent study finding a workload ratio of 1.5 being associated with risk of injury in rugby players; but, for those players who exceeded this threshold, they were 70 times more likely sustain a non-contact, soft-tissue injury (2). Yikes!
Now let's consider the difference between an external and internal workload for a moment and discuss why they matter. An external load is the actual amount of physical workload/training placed on the individual and the internal load is basically the perception of effort (i.e. the RPE). What this means is that for any given external load, lets say 2 hours of strength and conditioning, the internal workload (i.e. RPE) will be perceived differently from person to person. Does this matter? Consider the following: if Athlete A exercises for 2 hours at an RPE of 2/10 compared to Athlete B who works at an RPE of 9/10, will either of these athletes have a favorable adaptations to training? In this example, Athlete A is likely not loading enough while Athlete B could be overtraining. As discussed in Dr. Gabbett’s latest work found here (http://bjsm.bmj.com/content/early/2016/01/12/bjsports-2015-095788.full), there is likely a “sweet spot” for training which produces a favorable environment for physical adaptations to occur by balancing and considering the amount of load and perception of effort.
If we think logically about all this for a moment, it seems to be obvious stuff - going from a period of minimal loading to a lot of loading may result in injury. Secondly, for those who perceive the work to be either too easy or too hard, we are not going to produce optimal and sustainable results. Not only is this phenomenon applicable to sports, it is often seen in the general population. For example, what happens to the non-runner who starts training for the half marathon set to take place in two weeks? How does the office worker’s neck and shoulder feel when going from a 20 hour work week to a 50 hour work week filled with meetings and deadlines? Is the warehouse worker who unloads two trucks per day going to develop low back pain when jumping to six unloads per day?
Figure 3: Is your neck or back trying to tell you something? Monitor your physical and mental workloads - your body will thank you.
By being mindful of the acute (weekly) workloads in comparison to the chronic (monthly) workload, an injury risk profile can easily be developed. Thinking in these terms will mitigate risk, contextualize ‘overuse injuries’, and empower your patient education around dosing exercise and negotiating return to sport. There are also a lot of implications for off-season training; athletes need to be very careful about lowering their chronic workload during an off season and then diving right into training camp. This leads to a spike in their acute workloads, which is a perfect recipe for 70x the chance of injury.
So... what is the AMP’d Bottom Line:
Educate coaches, athletes, and your patients on the importance of monitoring workloads.
Find the right dose and ramp for the individual in front of you. Decide on an appropriate acute workload, and an appropriate ramp-up. This is entirely specific to the individual in front of you.
Monitor psychosocial load also: increased stress=increased risk of injury
Gabbett T. The training-injury prevention paradox: should athletes be training smarter and harder? BJSM. 2016
Hulin B, Gabbett T, Lawson D, Caputi P, Sampson J. The acute:chronic workload ratio predicts injury: high chronic workload may decrease injury risk in elite rugby league players. BJSM. 2015