Table 2.

Correlations between SF-36 physical functioning scores and aspects of PEM (N = 1534).

Items	Correlation with SF-36
Immediate PEM onset frequency	−.17**
Delayed PEM onset frequency	−.04
Length of delayed onset	−.04
How often do basic activities of daily living trigger PEM	−.45**
How often do positional changes trigger PEM	−.37**
How often do emotional events trigger PEM	−.18**
Total illness burden	−.39**
Length of prolonged duration	−.29**
How often is severity out-of-proportion to type of exertion	−.23**
How often is severity out-of-proportion to intensity of exertion	−.23**
How often is severity out-of-proportion to frequency of exertion	−.21**
How often is severity out-of-proportion to duration of exertion	−.24**
Pacing effectiveness	.18**

PEM: post-exertional malaise; SF-36: Short-Form Health Survey-36.

Items have been transformed to continuous variables based on time periods selected by the participant or frequency score.

^**p < .01.