Exploring the effects of mental and muscular fatigue in soccer players’ performance

Abstract

This study examined the effects of induced mental and muscular fatigue on soccer players' physical activity profile and collective behavior during small-sided games (SSG). Ten youth soccer players performed a 5vs5 SSG under three conditions: a) control, playing without any previous activity; b) muscular fatigue, playing after performing a repeated change-of-direction task; c) mental fatigue, playing after completing a 30 min Stroop color-word task. Players' positional data was used to compute time-motion and tactical-related variables. The muscular fatigue condition resulted in lower distances covered in high speeds (∼27%, 0.3; ±0.5) than the control condition. From the tactical perspective, the muscular fatigue condition resulted in lower distance between dyads and players spent ∼7% more time synchronized in longitudinal displacements than the control condition (0.3; ±0.3). Additionally, players spent ∼14% more time synchronized with muscular fatigue than with mental fatigue (0.7; ±0.3). The mental fatigue condition resulted in a very likely more predictable pattern in the distance between dyads than in muscular fatigue condition (0.4; ±0.2). Also, the mental fatigue possibly decreased the teams' stretch index when compared with control (0.2; ±0.3) and likely increased compared with muscular fatigue (0.5; ±0.5). The better levels of longitudinal synchronization after muscular fatigue, might suggest the usage of tactical-related tasks after intense exercise bouts. The lower physical performance and time spent longitudinally synchronized after mental fatigue, should alert to consider this variable before matches or training activities that aim to improve collective behavior.

Mental Fatigue in Soccer: A Systematic Review

“…In other two studies, no clear effects of mental fatigue were identified in small-sided games. 42,44 Coutinho et al 41 observed shorter total distances covered and Kunrath et al 43 found higher values of distance covered at speeds between 10 and 12.9 km/h and ≥ 18 km/h.…”

“…Four different cognitive tasks were used as a protocol for inducing mental fatigue, the AX-CPT (90 minutes), the Stroop paper [38][39][40][41] and computer version (20 -30 minutes) 42,43 , and the motor coordination task 44 . In control condition, the subjects read magazines [38][39][40] , watched TV documentaries 30,42 , and performed a warm-up lasting the same time as the intervention condition 44 .…”

“…Subjective scales were applied before and after cognitive tasks to verify the effectiveness to induce mental fatigue. Six studies used the Visual Analogue Scale (VAS) to measure the level of mental fatigue, mental effort and motivation [38][39][40][41][42]44 . One study applied the BRUMS questionnaire to evaluate the measures of fatigue and the Matthews, Campbell and Falconer scale 45 for motivation, while one study did not apply any subjective ratings.…”

“…Among them, only one found a decrease in VO 2 values during the physical task in mental fatigue condition. 30 Six studies measured physical variables 30,38,[41][42][43][44] using a laboratory protocol 30 and five studies 38,[41][42][43][44] used a field protocol. In the lab's protocol, Smith et al 30 verified a decrease in the total distance covered on the treadmill test and shorter distances covered at lower zones of speed.…”

Shared Demands Between Cognitive and Physical Tasks May Drive Negative Effects of Fatigue: A Focused Review

“…Coutinho et al (2017) similarly showed that after game-based and sports specific cognitive fatigue-inducing tasks players spent less time synchronized in the lateral direction and reduced their speed of team dispersion and contraction during the SSG. A follow up study by Coutinho et al (2018) improved on the design of the previous study (counterbalancing the fatigue condition between teams), and showed that after cognitive fatigue, there was a greater distance between dyads and a reduction in the teams' stretch index and time spent longitudinally synchronized as measured by GPS. Together, the results demonstrated that whilst cognitively fatigued, a player's ability to recognize important environmental cues and to properly monitor and adjust the performance in a timely manner becomes impaired.…”