Physical activity (PA) guidelines are informed by epidemiological evidence but do not account for people's motivation for exerting physical effort. Previous research has shown that people are less motivated to engage in moderate- to vigorous-intensity PA when fatigued. In a two-study series, we investigated how intensity and duration affected people's willingness to engage in PA using an effort-discounting paradigm. A secondary purpose was to examine whether effort discounting was affected by mental fatigue. Both studies revealed a significant Intensity × Duration interaction demonstrating a reduced willingness to engage in PA of higher intensities across increasing duration levels. Study 1 demonstrated greater effort discounting for vigorous-intensity PA with increasing mental fatigue; however, this effect was not observed in Study 2. Findings provide novel insight toward people's motivation for engaging in PA based on the properties of the task, and some evidence suggesting feelings of fatigue may also influence motivation to exert physical effort.

中文翻译：

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真的值得付出努力吗？检查精神疲劳对体力活动努力贴现的影响。

体力活动 (PA) 指南以流行病学证据为依据，但并未考虑人们进行体力活动的动机。先前的研究表明，人们在疲劳时不太愿意进行中等强度到高强度的体力活动。在一项包含两项研究的系列中，我们使用努力贴现范式调查了强度和持续时间如何影响人们参与 PA 的意愿。第二个目的是检查努力折扣是否受到精神疲劳的影响。这两项研究都揭示了显着的强度×持续时间相互作用，表明在持续时间水平增加的情况下，参与更高强度 PA 的意愿降低。研究 1 表明随着精神疲劳的增加，高强度 PA 的努力折扣更大；然而，在研究 2 中没有观察到这种效果。