In his most recent newsletter, Attia debunks the widespread takeaways of the wearable-data study suggesting that one minute of vigorous exercise can replace 156 minutes of low-intensity movement. I agree with his analysis of the study’s methodological and interpretive weaknesses and, especially, the unjustified takeaway in italics above. However, Attia is lax on one point when he says:
“The data come from wrist-worn accelerometers. This is likely an improvement over self-reported activity, but accelerometers measure movement, not physiological load.”
Accelerometer data is not necessarily or even likely an improvement over data derived from self-reported activity. With the proper design and procedures, self-reported data can be quite precise whereas accelerometer data will always be limited in terms of accurately characterizing physiological load and other relevant factors. The weaknesses in some studies employing self-reported activity or dietary practices generally reflect study constraints or low measurement standards.