Time Estimation Following an Exhaustive Exercise

Abstract

Background/Objectives: Time estimation was investigated in 24 healthy adults, including 12 women and 12 men, before and after an exhaustive exercise. Methods: We compared the ability of estimating time intervals in the range 1 to 5 s using tasks requiring mental counting and tasks that did not allow it. Time estimation and blood lactate levels were evaluated before and at the end of the exercise. Results: We found that the perception of time intervals between 1 and 5 s was affected at the end of the exercise. The observed effects, associated with a significant increase in blood lactate levels, were different in the two types of time estimation used in the present study. When participants had to evaluate the duration of the time interval using mental counting, a significant reduction in the overestimation of time made at rest was observed at the end of exercise. On the other hand, when participants had to assess the difference in duration between two events without the possibility of mental counting, a significant deterioration in performance was observed at the end of the exercise. In both cases, no differences were seen between genders. Conclusions: It could be hypothesized that an increase in blood lactate, acting as a type of physiological arousal, could contribute to the distortion of perceived time intervals. On the other hand, it does not yet seem possible to propose a model to explain the worsening of the perception of time when mental counting is not possible.

Keywords: blood lactate; exhaustive exercise; healthy adult; temporal processing; time; time estimation.

Figure 1

(A) summarizes Experiment 1. The subjects viewed a computer screen where a smiling yellow face appeared (1); after an interval randomly ranging from 1 to 5 s, a blue square appeared (2). The subject was instructed to mentally count for the estimation of the interval between the two visual stimuli. (B) summarizes Experiment 2. The subjects saw two vertically arranged blue squares on the computer screen (1). Following examiner command, one of the squares turned yellow (2). After a variable period, the second square turned yellow (3). The first one then turned blue again (4), followed by the second square (5). Subjects were asked to indicate verbally which square had been yellow for a longer period (the upper or the lower). Within a test series, the interval duration was constantly 1 or 2 s. However, the duration of the yellow phase of the two squares was randomly arranged to obtain differences in duration of 15%, 20%, 25%, 33% or 50%, with 15% indicating the most difficult condition (minimal difference between the two intervals) and 50% being the easiest condition (maximal difference between the two intervals).

Figure 2

Blood lactate values exhibited by the 12 women (W) and 12 men (M) participating in the present study. The graph on the left shows results obtained when participants had to estimate time by mental counting, and the graph on the right when mental counting was not allowed. In both cases, blood lactate mean values (±SD) measured before the exercise (pre), at its conclusion (end), and 5 min and 15 min after its end are illustrated. Symbols from ANOVA with Dunn’s multiple comparison test: ns, not significant; * p < 0.05; ** p < 0.01; *** p < 0.001.

Figure 3

Correlations between blood lactate levels and overestimation (expressed in percent) of 1–5 s time intervals in the whole sample (All) as well as in women and men using mental counting.

Figure 4

Correlations between blood lactate levels and number of correct answers evaluating difference between two short time intervals (≤5 s), measured in the whole sample (All) as well as in women (W) and men (M) without the possibility of using mental counting.

Figure 5

Correlations between the incidence of error (expressed in percent) and difference (expressed in percent) in the duration of the two visual stimuli used for test, before (pre) and at the end of the exhaustive exercise in the whole sample.