De Vrijer, A., & Bishop, D. (2009). Secret clock manipulation affects time-to-task failure during high-intensity exercise. A paper presented at the 14th Annual Congress of the European College of Sport Science, Oslo, Norway, June 24-27.

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This study tested the hypothesis that secretly manipulating the clock calibration would influence time-to-fatigue in healthy males (N = 8). Ss performed an incremental test on a cycle ergometer to determine power at VO2max (P100%), followed by a familiarization trial and three identical time-to-fatigue tests at P120%. During all tests, a large digital clock with the time of the test was visible to the Ss. During tests 3 and 4, the speed of the clock was either manipulated by a factor of 0.9 (slow clock) or 1.1 (fast clock). Ss were unaware of the time manipulation and the tests with the slow and fast clock were conducted double blind and in a random, counter-balanced order. Manipulated clock times were later converted to real times.

Time-to-fatigue was significantly longer with the fast clock compared to the slow clock. The average time-to-fatigue of the normal clock was not significantly different from the other two conditions. Heart rate at task failure was significantly higher in the trial with the fast clock compared to the slow clock, but was not different from the normal clock. There was no significant difference in VO2 between the three conditions.

Implication. Ss increase time-to-fatigue when looking at a fast compared to a slow clock. This offers strong evidence that task failure is not only related to physiological factors, but is also influenced by perception.

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