Mental Fatigue From Smartphone Use Reduces Volume-Load in Resistance Training: A Randomized, Single-Blinded Cross-Over Study

Percept Mot Skills. 2021 Aug;128(4):1640-1659. doi: 10.1177/00315125211016233. Epub 2021 May 17.


We investigated the acute effects of mental fatigue induced by 30-minute use of smartphone social network apps on volume load in resistance training among recreationally trained adults. Sixteen (n = 16) adults of both sexes performed three sets of a half back-squat exercise to failure with 80% of 15RM, interspersed with 3-minutes of passive recovery between sets, before and after two different cognitive tasks: (a) use of smartphone social network apps; and (b) watching a documentary. We assessed mechanical variables and ratings of perceived exertion during the strength exercise. Relative to the documentary-viewing control condition, a 30-minute exposure to smartphone social network apps led participants toward increased perception of mental fatigue (p = 0.004) and lower volume-load during the strength exercise (p = 0.006). There were no significant differences in perceived exertion between conditions (p = 0.54), participants' motivation (p = 0.277), intra-set mechanical variables (p > 0.05), or blood lactate concentrations (p = 0.36). Our findings of an isolated possible higher-than normal RPE without changes in physiological variables, accompanying the lower volume-load in the mentally-fatigued participants support psychological, rather than physiological, bases for mental fatigue effects.

Keywords: concentric mean velocity; mental fatigue; perceived exertion; resistance exercise; volume-load.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Cross-Over Studies
  • Exercise
  • Female
  • Humans
  • Male
  • Mental Fatigue
  • Physical Exertion
  • Resistance Training*
  • Smartphone