By Erin Robson - Physiotherapist

Whether you are training for a sporting event, rehabilitating an injury or just into your general fitness – a lot of factors come into play to ensure effective progression is made. How often, what intensity, what exercises and how much rest will all be determining factors in moving forward efficiently. These are the factors that determine what we call the ‘training load’. This article will break down some of the science and answer the questions of how often, what intensity, what exercises and how much rest is suitable for you.

To help answer some of these questions, let’s break down training loads into 2 aspects…
 
1.    Mechanotransduction
This fancy term is super important in the rehabilitation of injuries and when planning training sessions. It relates to how the tissue (muscles, tendon, ligament & bone) cells react when you apply load or force.


In simple terms, cells are lazy. A cell will not improve its capacity without being stressed/loaded. The cells need to adapt to this load for it to initiate growth and/or repair.
This forms the scientific basis for the exercise rehabilitation of injuries and is why complete rest is not advisable for most musculoskeletal conditions, e.g muscles tears/weaknesses, tendinopathies, stress fractures, osteoporosis and joint sprains/ligament tears. Complete rest will further reduce tissue cell capacities.

A few factors are important when planning the exercise/rehabilitation (i.e. load):

a. How much load? As a basic guideline, pain can be used (if rehabilitating an injury). For each exercise, load as much as possible as long as a) pain stays below a comfortable limit b) pain does not increase with the exercise/at rest/day-to-day c) safe techniques are used.
Follow common exercise prescription guidelines (e.g. 3 sets of 10 reps for strength) for strength/endurance/power (whatever you need to work on - depending on your injury, condition, sport, weaknesses etc.).

b. What type of load? Cells will adapt to only the specific load that is applied, and will become strong resisting that force only. Hence, comprehensive and variational training is important. As is training the tissue in the way/position it was damaged (as this indicates a weakness). 

c. Timelines are also important. It is important for both the clinician and the client to understand the length of time required for tissue changes to be made, and to take into account all other factors, e.g how long the injury has been around. 


2.    Training frequency & intensity
Ideal training is high enough to result in maximum gains in fitness without causing or risking injury.


Training loads can be split into 2 categories: acute workload and chronic workloads. Acute workload is the training load over the most recent week. The chronic workload is the 4-week rolling average of each week’s workload. For training load to be ideal, it is critical to consider an individual’s acute:chronic ratio. In simple terms, if your exercise-load over 1 week is more than the average load of the past 4-weeks, then you will be at risk of injury. Hence, a high chronic workload minimises injury risk/protects athletes from injury. To increase fitness, training loads must increase (as per the mechanotransduction discussion above). To minimise risk of injury, changes in training must be kept to below 10% per week.

To sum up: to optimally train/rehabilitate, you need to gradually increase your workload each week (by less than 10%) so that you have a high average of exercise each month. This will protect you form injury and ensure you are prepared for spikes in load (e.g competitions, events etc).

This concept of maintaining a high chronic workload to prevent injury brings about the suggestion that “over-use” injuries are improperly named, and are theoretically “under-prepared” injuries.

Rest is also important to consider when planning training.  As above, changes in training should be kept below 10%, this includes decreases, as well as increases post rest periods. Also, any rest taken will influence time needed to re-ramp training/load. Please see the below graph demonstrating the time needed to return to full training post rest (more than you would expect..)

If you take 2 weeks off training, follow the blue line. For example, if you spend 2 weeks doing 40% of your normal training, it will take almost 3 weeks of ramping back to full training, to prevent an injury risk. OR If you spend 2 weeks doing 0% of your normal training, it will take 4 weeks. If you've taken 4 weeks off, follow the yellow line, respective to the amount of training you've done.

Another important fact to note, is that after an injury risk (e.g. too much or not enough training) it can take up to 4 weeks for an injury to occur. 

 

So, in summary:
•    Varied, purposeful training is key
•    Find, measure & train weaknesses
•    Maintain safe, purposeful training if injured
•    Keep changes in training to <10% per week
•    Maintain high chronic workloads (avoid regular/prolonged rest periods)

Good luck and if you have any questions or would more information give our physiotherapy and exercise physiology team a call at The Biomechanics, or drop in and say hi in Footscray!

 

 

References:
Khan, K & Scott, A. (2009). Mechanotherapy: how physical therapists’ prescription of exercise promotes tissue repair. British Journal of Sports Medicine, 43: 247-251. doi 10.1136/bjsm.2008.054239

Gabbett, TJ et al. (2016). High training workloads alone do not cause sports injuries: how you get there is the real issue. British Journal of Sports Medicine, doi 10.1136/bjsports-2015-095567

Charlton, P & Drew, M. (2015). Can we think about training loads differently? Australian Institute of Sport, http://www.ausport.gov.au/__data/assets/pdf_file/0006/646755/Can_we_think_about_training_loads_differently.pdf