Comparison of Weekly Training Load and Acute: Chronic Workload Ratio Methods to Estimate Change in Training Load in Running.

Context: Before examining the impact of training load on injury risk in runners, it is important to gain insight into the differences between methods that are used to measure change in training load.

Objective: To investigate differences between 4 methods when calculating change in training load: (1) weekly training load; (2) acute : chronic workload ratio (ACWR), coupled rolling average (RA); (3) ACWR, uncoupled RA; (4) ACWR, exponentially weighted moving average (EWMA).

Design: Descriptive epidemiology study.

Setting: This study is part of a randomized controlled trial on running injury prevention among recreational runners. Runners received a baseline questionnaire and a request to share global positioning system training data.

Patients or other participants: Runners who registered for running events (distances 10-42.195 km) in the Netherlands.

Main outcome measure(s): The primary outcome measure was the predefined significant increase in training load (weekly training loads ≥ 30% progression and ACWRs ≥ 1.5), based on training distance. Proportional Venn diagrams visualized the differences between the methods.

Results: A total of 430 participants (73.3% men; mean age = 44.3 ± 12.2 years) shared their global positioning system training data for a total of 22 839 training sessions. For the weekly training load, coupled RA, uncoupled RA, and EWMA method, respectively, 33.4% (95% CI = 32.8, 34.0), 16.2% (95% CI = 15.7, 16.6), 25.8% (95% CI = 25.3, 26.4), and 18.9% (95% CI = 18.4, 19.4) of the training sessions were classified as significant increases in training load. Of the training sessions with significant increases in training load, 43.0% from the weekly training load method were different than the coupled RA and EWMA methods. Training sessions with significant increases in training load based on the coupled RA method showed 100% overlap with the uncoupled RA and EWMA methods.

Conclusions: The difference in the change in training load measured by weekly training load and ACWR methods was high. To validate an appropriate measure of change in training load in runners, future research on the association between training loads and running-related injury risk is needed.