The current study examined the variables that influence postreinforcement pause (PRP) duration in rats when wheel running serves as the reinforcing consequence. The relationship between revolutions and PRP duration when revolutions were manipulated within a session and the effect of changing the response requirement from fixed to variable on PRP duration were evaluated. The operant was lever pressing and the reinforcer was the opportunity to run for a programmed number of revolutions. Results failed to show a positive correlation between revolutions run and PRP duration but did show that PRP duration was decreased by a variable response requirement. Analysis also revealed a within-session decrease in PRP duration. The implications of these findings for understanding the factors that influence PRP duration with wheel-running reinforcement are discussed. (Contains 2 figures and 1 table.)