There is a strong knowledge out there that exercise is highly recommended. Exercise can result in increasing strength, decreasing body fat and other health benefits. A common misconception is exercise being a cause for injury. Though not completely incorrect, there is a precise amount of exercise that can predict the risk of injury in an individual.
Before looking into how much is too much exercise, we first must take a step back into how we organise exercise. As we have earlier established, exercise can be calculated in terms of volume or total work output (TWO). For a quick refresher on TWO and how to calculate, refer to my previous blog post, Total Work Output – And How We Use it For Workplace Rehab!
With the use of this information, we can organise exercise programming into phases. This organised method of training and TWO is also known as Periodisation.
Periodisation follows into multiple stages or phases. These phases have certain goals and outcomes. These phases are shown below:
The accumulation phase is where the individual will first begin with light training loads with the appropriate intensity for the individual. The goals for this phase are to allow for the individual to accumulate a gradual amount of fatigue to allow for physiological adaptations and practice technique for neural adaptations.
The intensification phase is where the individual will begin to decrease the higher amounts of volume that was seen in the accumulation phase. Intensification phases generally has the weights being heavier. This would mean for optimal outcomes and avoiding of injuries, reps would have to decrease to allow for the appropriate exposure, and have the individual go through both physical and neural adaptations for less risk of injury.
The realisation phase is where we test for results and see how successful the training program has become. If the individual has applied themselves during all phases and the periodised training program has been catered to the person, the wanted outcome should result.
This is where the knowledge of training phases, TWO and Volumes of exercise can help us understand risk of injuries. Looking at the graph below, we can see the relationship between the likelihood of injures and exposure to acute & chronic workloads. Being a parabolic relationship between the two, there is an interesting effect that can occur between the two.
Let’s begin looking at the red area, labelled the “Danger Zone” where we are likely to see an increased injury risk. This area begins when an individual is exposed to roughly a ratio of 1.5 between acute and chronic workloads, approximately 50% more than what they’re used to. This could be the in the form of more sets, reps or weight being lifted and in either the accumulation or intensity phases.
Now looking at the “Sweet Spot”, where there is a decreased risk of injury. This is approximately at the ratio ranges of 0.90 to 1.4. From this graph, it determines that an individual is less likely to hurt themselves in these ranges of work, and that it should be taken into consideration when prescribing loads into specific phases of training. If the ratio increases too fast we risk injuries, so what’s the safest intensity increase to prescribe for optimal adaptation? This would be a case by case situation with individuals, but it’d be safe to say an increase of 0.10 in workload ratio would allow for body adaptations and a decreased risk of injury.
As mentioned before, the relationship of likelihood of injuries and the workload ratio is parabolic. To be put in simple terms, if a person’s workload increases too much, the person gets injured. If you give the person a workload in the “Sweet spot”, their risk of injury decreases. But if we prescribe an individual a workload less than optimal, their risk of injury increases more than the given optimal load. The reason for this, is that the individual has now begun to undergo a process which we call detraining. This means that the physical adaptations have not occurred due to too little stimulus, and the body is no longer prepared for the task at hand.
So how can we use this in the real world? Without being too calculative, it’s important to know that the body is a reactive system. If we put too much of a stimulus such as exercise on the body, we will begin to wear down and increase our risk of injury. But if we take away exercise, our body will begin to unadapt, and we will be deconditioning our body. It’s a matter of art and science to find the right stimulus within the “sweet spot” ranges to decrease the risk of injury as much as possible while still finding what will result in maximum outcome, either in exercise outcomes or health benefits.
Sean Koh (BSc – Ex.Sp.Sci, Post.Grad.Dip.(Clin.Ex.Phys))
Accredited Exercise Physiologist, Accredited Exercise Scientist (AEP) (AES) (ESSAM)
1) Periodization: Theory and Methodology of Training, Tudor, Bompa O., Haff, Greg G. (2012)
2) Gabbett, T. (2016) The Training – injury prevention paradox: should athletes be training smarter and harder?