# Motor Imagery and Sport Performance: A Systematic Review on the PETTLEP Model
## 1 Introduction  
Motor imagery (MI) is the act of mentally rehearsing voluntary movements without engaging in the actual corresponding motor actions, as described by cognitive neuroscientists [1]. The overlapping of many neural substrates of motor imagery and motor execution involves cortical and subcortical areas such as the primary motor cortex [2; 3; 4; 5], the premotor cortex, the supplementary motor area, the anterior cingulate cortex, the parietal lobule and the cerebellum [6; 7; 8], and even some vegetative indices [9; 10; 11]. This is at the basis of the \"functional equivalence theory\" [6; 12; 13], which relies on three factors: the same duration for the executed and imagined task [14], more time required for more complex movements [15], and correlation between the force required for the motor task execution and the mental effort during its imagination [16]. Consequently, MI practice could hence facilitate the successive motor execution [2; 13] and could lead to increased brain plasticity fundamental for motor-skill learning [17; 18]. Furthermore, MI is supposed to result in increased excitability of spinal motor neurons [19; 20], which leads to a greater neural impulse reaching the agonist muscle [21], eventually increasing the activity of such a muscle [22; 23; 24; 25]. Moreover, MI may modify movement-related cortical potentials, which are comparable to those observed with physical practice (PP) [26].  
This can result in a better synchronization of the muscle fibers and inhibition of the antagonist muscle [22], eventually increasing strength [22; 26]. These findings suggest that such common neural circuitry might underpin an increased performance efficacy induced by MI in athletes [27; 28]. Motor imagery can be distinguished depending on the strategy adopted by the subject that is asked to mentally recite a motor task. Visual motor imagery consists in producing a visual representation of one's moving limbs. Kinetic motor imagery requires the subject to use the physical feeling of the movement to rehearse it [29; 30]. Atthe neural level, it has been demonstrated that the associative parietal cortex processes information necessary for MI. Indeed, this area is not only in charge of controlling posture and strength in the course of the executed movement, but it also plays a role in forming the body image and its relation to the outer world [31].  
Several models propose that motor imagery, movement execution, and action observation recruit the same brain regions, but recent observations have suggested that the functional equivalence in subcortical areas is related to the first two acts, whereas action observation did not consistently recruit any subcortical areas [32]. Among the motor imagery models that could have a practical application, the most interesting seems to be the PETTLEP model, which takes into account many different domains related to motor imagery: physical features, environment, task-related aspects, timing equivalence, learning, emotion, and perspective.  
This mixed review, reporting qualitative and quantitative results, aims to critically analyze the evidence provided throughout the years regarding the application of motor imagery (MI) in sport performance, conducted in agreement with the criteria of the PETTLEP approach.  
Ahletes typically adopt this method when attempting to enhance their performance [33]. Furthermore, following sport injury, MI is endorsed either concomitant to physical practice or as a temporary back-up during immobilization periods [34]. MI is particularly useful in conditions where practical limitations inhibit physical training, including biomechanical rigidity, poor physical strength, fatigue, injury risk, and limited access to equipment. In the present review, we focused on the application of motor imaging in the enhancement of sport performance and in sport rehabilitation of athletes.