Load Management

 

Load management principles are used daily in high-end strength and conditioning/sports settings and are critically important in measuring relative injury risk and determining optimal load.

However, the concept of load management may not be limited to high-performance sports or training settings. There are principals of this concept that are applicable in non-sporting settings (eg. day to day activities, work, and leisure). Exploring the wider contexts to which load management principals can be used may assist in reducing overuse/chronic injury risk for the general population.

 

Let’s Talk Science

 

The Acute to Chronic Workload Ratio (ACWR)

A concept developed based on the idea of an ideal training stimulus having the capability to maximise performance through the use of appropriate training loads while limiting negative training consequences (injury and fatigue). The ACWR describes two workload zones, the ‘sweet spot’ and the ‘danger zone’ which represent the likelihood of subsequent injury.

The ‘sweet spot’ is represented in the graph below as a ratio range between 0.8 and 1.3. The ‘danger zone’ is represented as a ratio greater than 1.5.

Acute:Chronic Workload Ratio

 

Calculating ACWR & Load: Acute vs Chronic

 

Acute Workload:

In a training setting, this is typically calculated over a 7-day block (average of daily acute workloads). Measures of the sessional rating of perceived exertion (sRPE) times by the duration of the training session would represent the acute load for a day. Example: If sRPE (perceived difficulty) of a 100-minute session is 5 this would equal 500 arbitrary units (AU) (5*100 = 500 AU).

Chronic Workload:

The chronic load can be calculated as an average of the acute workloads.

Example:

Week 1: 500 AU

Week 2: 700 AU

Week 3: 600 AU

Week 4: 300 AU

Chronic Load: (500 + 700 + 600 + 300)/4) = 525 AU

ACWR: Acute Load (Week 5: 700AU)/Chronic Load – (700 / 525) = 1.3

To give some commentary to the above equation: If the acute workload for week 5 was to be 700 AU then the ACWR for that period would be 1.3. A value of 1.3 would represent the top end of the “sweet spot” bracket, meaning that the subsequent injury risk for that week is relatively low. If that acute load was to change to say 900 AU then the ratio would be 1.7 and the injury risk would be relatively greater.

 

 

Application to YOU

 

ACWR in an occupational setting

 

Both internal and external load is inevitable in the workplace, there is no hiding from the fact. The table above displays the application of the ACWR as a load management tool for individuals across a wide range of occupations. As you can see all scenarios have the capacity to create positive or negative outcomes. The outcome is primarily dependent on the preparedness of the individual to that specific task.

Looking specifically at the receptionist, the increase in acute load may come from working longer days during a busy period or working more days in the week to cover for a colleague who is sick for example. These factors can drive up the acute load, inherently increasing injury risk (eg. overuse injuries, such as a repetitive strain injury), leaving the individual unable to work.

However, this doesn’t only apply to occupational tasks…

Simple scenarios such as going for a 10km bike ride after just dusting your bike off from a 10-year absence of use or going on an overseas holiday where you may be walking over 10km per day while being lucky to clock up 2km at home during a normal day; both are examples of a spike in acute load far beyond that of the chronic load.

 

Take Home Points

 

  • Ensure that you are prepared for any task you will be completing; whether it be walking, running, cycling, gardening, working, playing sport.
  • Be mindful of what your body is used to and try to avoid the spikes in acute load for any given task; should you want to reduce the risk of developing any injuries.

About the Author