Researchers had three groups of professional cyclists cycle for one hour at different levels of intensity.
Given
Researchers had three groups of professional cyclists cycle for one hour at different levels of intensity.
Members of groups A, B, and C cycled at rates that sustained, for an hour, pulses of about 60 percent, 70 percent, and 85 percent, respectively, of the recommended maximum pulse rate for recreational cyclists.
Most members of Group A reported being less depressed and angry afterward.
Most members of Group B did not report these benefits.
Most members of Group C reported feeling worse in these respects than before the exercise.
Evaluate
We have this set of contrasts. This seems like the type of stimulus that could set up a "One Difference Explains Another" type of inference. Maybe difference in pulse rates explains the difference in psychological benefits. We'd want a very safely worded answer though, since this is speculative causality, not explicit causality.