Reader Comments

Post a new comment on this article

What does this mean in biological terms?

Posted by SMcGrath on 19 Nov 2012 at 11:24 GMT

There was also a significant group x cubic trend interaction [F(1,68) = 4.16, p = 0.04; ηp2 = 0.06]

As before, I'm struggling to understand the meaning of a "group x cubic interaction" and would appreciate a fuller explanation. Thanks.

No competing interests declared.

RE: What does this mean in biological terms?

ute_vollmer-conna replied to SMcGrath on 21 Nov 2012 at 05:20 GMT

For this one, place refer to Figure 1. As explained for the other comment, "group x cubic interaction" refers to a repeated measures trend analysis. Here we looked at differences in the pattern of HR responses between the two groups. The control participants show a cubic trend in their HR response across the tests (i.e. HR increases, then stays flat, and then increases more = 2 bends in the pattern). This cubic pattern is significantly different from the more linear pattern shown by patients with CFS (HR keeps going up through out irrespective of the difficulty of the test they do).
Again biologically this suggests that the autonomic nervous system in participants with CFS is hyper-responsive to the stressor (i.e. the tests) and it does not show the usual flexibility in the response that reflects dynamic adjustments depending on how demanding the task is.

Competing interests declared: I am the senior author on this paper