The Magic Number to Reduce Injury Risk

For those who continue to foam roll, spend hours on mobility drills, or hammer home technique but still find yourselves injured - you might be barking up the wrong tree.

The simple answer might be, you are doing too much. Most of us understand that rest is essential and over-training is detrimental, and yet, for some reason, doing less is never the answer. There has got to be more to it, nope, sorry guys, there is not. Here is what you need to know to stay pain-free and reduce your injury risk:

What is training volume?

Volume is the total amount of weight lifted, or distance traveled (for our runners) in a training session. For example, if someone performed a total of 10 sets of 100 pounds at 5 reps per set, their training volume for that day would look like this:

10 sets x 100 lbs x 5 reps = 5000 lbs

And the same would go for running, except with more nuance.

From here we could easily account for the total volume of weight lifted in a week, month, or year.

Why is this important?

Measuring training volume allows us to monitor the work we've done relative to the work we are currently doing. This is very important because:

Training volume might be the most critical variable when it comes to injury prevention and injury risk.

Not posture, corrective exercises, or mobility work. This idea is explained using Tim Gabbett's concept of acute-to-chronic workload ratios (ACWR).

What is the Acute to Chronic Work Load Ratio?

The concept is defined as your acute (1 week) training volume, versus your chronic (3 - 6-week training volume), or as your fatigue (acute) state versus your training (chronic) state.

Taken from the example above, one could calculate their acute training load versus their chronic training load, using weekly volume as follows:

1 week training volume = 20000 lbs (acute),  3 week average volume = 15000 lbs (chronic)

ACWR = 20000/15000 = 1.3

According to his research, the "sweet spot" for decreased injury risk is .8 to 1.3 and anything outside this zone increases the risk for injury.

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His research using ACWR showed that elite cricket bowlers risks for injury increased by 2 to 4 times when their acute to chronic workload ratio was greater than 1.5 within 7 days. This has subsequently been confirmed for elite soccer and rugby players as well.

How can we use this to train smarter?

In practical terms, by increasing our volume methodically, staying in the "sweet spot" and avoiding any large spikes or dips, we can reduce the risk for injury over time. This works well when tracking reps and sets, but what about when we are dealing with cross-fitters, professional athletes, or any physical activity that is difficult to track.

In these situations, it might be better to use arbitrary units (AU) as a function of the rating of perceived exhaustion scale multiplied by the time of the training session ( RPE x Training Time ).

An example would look like:

Training session Duration: 100 minutes

Self-reported RPE: 8

Acute workload ratio: 800 (AU)

Based on RPE x session duration formula one could track their weekly (AU) and rolling 4-week average (AU) to make sure they stay within the "sweet zone" and limit injury risk.

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Conclusion

Over-training, under-training, and large spikes or dips in training volume might be the real reason why you keep getting injured. Use this advice to train optimally, find your "sweet spot" and reduce injury risk. We hope you enjoyed, and happy lifting.

Citation:  

Gabbett TJ The training—injury prevention paradox: should athletes be training smarter and harder?Br J Sports Med 2016;50:273-280.

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