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

Abstract

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.

Can Prolongate Use of Social Media Immediately Before Training Worsen High Level Male Volleyball Players’ Visuomotor Skills?

“…Considering both these results and previous findings regarding prolonged social media use immediately prior to perceptual-cognitive or physical tasks (Fortes et al, 2019; Fortes et al, 2021a; Fortes et al, 2021b; Gantois et al, 2021), the mental fatigue protocols in these experiments should be better controlled so that the amount, type, and duration time of visual stimuli might be standardized for all participants. Also, the size of the smartphone screen could be standardized.…”

“…Thompson et al (2020) showed that ∼58% of English academy players reported using social media as a pre-match activity. Previous investigators found that after prolonged social media use on a smartphone, participants showed reduced volume-load in a resistance exercise session (Gantois et al, 2021) and in an impaired swimming performance (Fortes et al, 2021b). Thus, the prolonged demands for high visual attention of social media may induce performance decrements related to mental fatigue.…”

Mental fatigue impairs the number of repetitions to muscular failure in the half back‐squat exercise for low‐ and mid‐ but not high‐intensity resistance exercise

“…(2021) and Gantois et al. (2021) found reduced repetitions to failure using comparable intensity‐load in the half back‐squat exercise. Queiros et al.…”

“…These investigations used an intensity load of 40% (Graham et al., 2017), 60% (Queiros et al., 2021), and 70% 1RM (Gantois et al., 2021) in multiple set lower limbs exercise. Previous studies have used low to mid intensity‐load, which allows the individual to remain in the task longer than 30‐s.…”

Mental Fatigue Prior to Aerobic Exercise Reduces Exercise Pleasure and Negatively Affects Implicit Attitudes Toward Future Exercise

“…The impact of MF on RPE has been well documented in exercise research, even considering different types of physical exercise. For example, trained adults undergoing resistance training (i.e., 70% of 1RM and 80% of 15RM; Gantois et al, 2021; Lima-Junior et al, 2021; Queiros et al, 2021) or cycling high intensity (i.e., 80% of peak power output; Marcora et al, 2009) reported higher RPE during the session when under MF than non-MF conditions. We replicated and extended this finding to insufficiently active adults undergoing physical exercise at moderate intensity, reinforcing MF’s importance in different exercise intensities with a wider range of participants.…”