Fig. 2: A physical activity stressor-response process characterized by varying direction and pace.
From: Predicting recovery after stressors using step count data derived from activity monitors
a Conceptual visualization of various responses to stressors, with the overall response trajectory characterized by varying momentary pace and direction. b−d The within-person progression throughout the response process can be characterized by different rates of change, indicating whether the momentary pace is fast or slow (b vs. c), positive or negative (b, c vs. d). The rate of change, dy, reflects how much the outcome variable (here, step count) changes in response to a one-unit change, dt, in the independent variable (here, time). The rate of change can be operationalized as the first-order derivative of a growth function fitting the outcome variable. It can take positive, negative, or zero values depending on whether the change is positive, negative, or null.
