Figure 4.

Pressure pain thresholds: Pressure pain thresholds of the low back (A, erector spinae muscle), leg (B, gastrocnemius muscle), and shoulder region (C, deltoid muscle; D, trapezius muscle) were assessed using a handheld algometer 3 hours after injection of either lipopolysaccharide (LPS; 0.4 ng/kg body weight) or saline (placebo) in healthy men and in healthy women on hormonal contraceptives. Lipopolysaccharide application led to significant decreased pressure pain thresholds (for results of analysis of variance, see text). Women displayed significantly lower pressure pain thresholds compared with men (*P < 0.05, **P < 0.01, results of post hoc independent samples t tests), whereas no evidence of sex × condition interactions was observed. For results of analysis of variance and results from additionally computed exploratory within group comparisons, see text.