Acute vs Chronic Workload

Manage your training load and frequency properly and there is high probability you won’t miss that next workout.  

We work with runners, strength based athletes (powerlifters, olympic lifters, crossfitters) and team sport athletes on a daily basis. One of the common themes we see in regards to causative factors for overuse injuries is a quick increase in acute vs chronic workloads. What does that all mean and how does it apply to your sport or injury?

If you are a runner, your chronic workload is the average of your last 4 weeks in running volume and your acute workload would be your current week’s mileage. For example;

• Week 1: 40km
• Week 2: 50km
• Week 3: 48km
• Week 4: 62km
• Chronic Workload: 50km
• Acute Workload: 62km
• Acute:Chronic Workload Ratio = 1.24 (Right in the Sweet Spot, See Below)
  • 62km (Acute) / 50km (Chronic) = 1.24

If you are worried about pressing movements contributing to your shoulder pain, you can use all of your pressing volume to figure out if your training is being managed appropriately; 

• Overhead Lifting Reps x Weight
  • Week 1: Overhead Press: 
    • 50lbs x10 = 500, 60 x 8 = 480, 70 x 6 x 3 = 1260
  • Week 2: Overhead Press: 1330 
    • + 95lb Thrusters in a Wod x 40 reps = 5130
  • Week 3: 1420
  • Week 4: Overhead Press: 1420 
    • + 95lb Thrusters in a WOD x 90 reps = 9970
  • Acute Workload: 9970
  • Chronic Workload: 4445
  • Acute:Chronic Workload Ratio = 2.24 

Comparing the acute workload to the chronic workload as a ratio is an easy way to understand an athlete’s preparedness to train, their fatigue state and their risk of injury. This ratio allows practitioners and coaches to consider the training-load the athlete has performed recently (within the last training week) relative to the training-load the athlete has prepared for (within the last four weeks).

• < 0.80 (Under training and higher relative injury risk)
• 80 – 1.30 (Optimal workload and lowest relative injury risk – “The Sweet Spot”) 
• > 1.50 (The “danger zone” and highest relative injury risk)
• These numbers do not apply to every sport and every athlete but offer a general guideline for monitoring. 

Higher chronic workloads have been shown to be injury resistant as long as acute loads do not exceed ratios over 1.3. When they do, higher chronic workloads tend to be more causative of injury.

Too often patients are told they should stop doing an activity altogether as they “recover” or seek treatment. This thinking or advice actually can contribute to or prolong their injury. If running each week closer to your chronic workload keeps you relatively pain free as you build capacity, this is a better choice than taking weeks off and throwing off your ratios altogether. Train smarter, not harder and be mindful of these factors as you build capacity.

As Dr. Andreo Spina of Functional Anatomy Seminars teaches in his FRC course:

• Load > Capacity = Injury
• Capacity > Load = Prevention

Build your capacity and be mindful of your training loads. If you have any questions or need guidance in your training, reach out to one of our physiotherapists at Defy.

References:

1. Saragiotto BT, Yamato TP, Hespanhol Junior LC, Rainbow MJ, Davis IS, et al. (2014) What are the main risk factors for running-related injuries? Sports Med.
2. Billy T Hulin, Tim J Gabbett, Daniel W Lawson, Peter Caputi, John A Sampson (2015).  The acute:chronic workload ratio predicts injury:high chronic workload may decrease injury riskin elite rugby league players.  BJSM: 0:1-7.
3. Bengtsson, H., Ekstrand, J. and Hägglund, M., 2013. Muscle injury rates in professional football increase with fixture congestion: an 11-year follow-up of the UEFA Champions League injury study.British Journal of Sports Medicine, 47(12), pp.743-747
4. Bourdon, P., Cardinale, M., Murray, A., Gastin, P., Kellmann, M., Varley, M., Gabbett, T., Coutts, A., Burgess, D., Gregson, W. and Cable, N., 2017. Monitoring Athlete Training Loads: Consensus Statement. International Journal of Sports Physiology and Performance, 12, pp. S2-161-S2-170.
5. Malone, S., Owen, A., Newton, M., Mendes, B., Collins, K. and Gabbett, T., 2017. The acute: chronic workload ratio in relation to injury risk in professional soccer.Journal of Science and Medicine in Sport, 20(6), pp.561-565.

FAQs:

1. What is acute workload? This is the workload over a week of training. When talking about runners this usually the number of kilometers ran for a given week.
2. What is chronic workload? This is the 4-week average of training workload. Divide the total of the past 4 weeks of training and that number will be your chronic workload.