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This study used functional magnetic resonance imaging (fMRI) to investigate differences in brain activity between one group of active high jumpers and one group of high jumping novices (controls) when performing motor imagery of a high jump. It was also investigated how internal imagery training affects neural activity. The results showed that active high jumpers primarily activated motor areas, e.g. pre-motor cortex and cerebellum. Novices activated visual areas, e.g. superior occipital cortex. Imagery training resulted in a reduction of activity in parietal cortex. These results indicate that in order to use an internal perspective during motor imagery of a complex skill, one must have well established motor representations of the skill which then translates into a motor/internal pattern of brain activity. If not, an external perspective will be used and the corresponding brain activation will be a visual/external pattern. Moreover, the findings imply that imagery training reduces the activity in parietal cortex suggesting that imagery is performed more automatic and results in a more efficient motor representation more easily accessed during motor performance. MOTOR REPRESENTATIONS AND PRACTICE AF-FECT BRAIN SYSTEMS UNDERLYING IMAGERY: An fMRI Study of Internal Imagery in Novices and Active High JumpersMotor imagery can be defined as mental execution of an action without any muscular movement [1]. Between 70 to 90 % of elite athletes report that they use imagery with the intention of enhancing their physical performance [2], and controlled studies have shown that imagery leads to increased performance on motor tasks (for overview see [3,4]).One explanation for why motor imagery can enhance actual motor performance is that motor imagery and motor action engage overlapping brain systems [5,6]. Components that are critical for motor functions include the primary motor cortex (M1), the pre-motor cortex (PM), and the supplementary motor area (SMA). These regions are also found active in studies comparing motor imagery and motor performance, however, the results vary. Some studies show that there are equal activations in SMA and pre-motor cortex during imagery and physical performance [7,8]. In other studies SMA and pre-motor cortex are both activated during imagery as well as execution, but during imagery the extent of the activation is smaller [9][10][11][12]. Further, in some studies the regional extents are similar, but during imagery the activation is weaker than during physical performance [13][14][15][16].One factor that may account for the weaker and more variable activation patterns during motor imagery is the

Since long, motor imagery has been recognized as a method for studying motor representations. In the last few years, important advances regarding the use of motor imagery have been made. In particular, issues concerning the functional equivalence between imagery and action have been addressed, and how equivalence affects the use of imagery to study motor representations. In this paper, we review recent findings in order to highlight the current state of knowledge about motor imagery and its relation to motor action. Three topics are discussed: (i) the imagery perspective, (ii) task complexity, and (iii) the importance of physical experience. It is shown how theses factors are closely related and how previous studies may have underestimated to what extent these factors affect the interpretation of results. Practical implications for imagery interventions are considered. It is concluded that if you cannot perform an action physically, you cannot imagine it in a way that is necessary for a high degree of functional equivalence.

The main purpose of this study was to examine whether the use of internal imagery would affect high jumping performance for active high jumping athletes. Over a period of six weeks, a group of active high jumpers were trained with an internal imagery program for a total of 72 minutes. This group was compared to a control group consisting of active high jumpers that only maintained their regular work-outs during the same time period. Four variables were measured; jumping height, number of failed attempts, take-off angle, and bar clearance. There was a significant improvement on bar clearance for the group that trained imagery (p < 0.05) but not for the control group. No other differences were found. The results suggest that internal imagery training may be used to improve a component of a complex motor skill. Possible explanations and future recommendations are discussed.

The purpose of this study was to investigate: (a) If variables from 1-leg drop jump (DJ), DJ, squat jump (SJ), and countermovement jump (CMJ) tests can predict sprint performances for sprinters. (b) If sprinters and jumpers can be distinguished based on variables from 1-leg DJ, DJ, SJ, and CMJ tests, also if sprinters and throwers can be distinguished based on variables from stiff leg jump (SLJ), SJ, and CMJ tests. A single linear regression and multiple linear regression analysis approach with models including 2 or 3 variables were used when predicting sprint performances. Five elite sprinters (1 woman) participated in the first subexamination and 5 sprinters (1 woman) vs. 5 jumpers and 6 sprinters vs. 6 throwers (4 women) participated in the second. The force variable CMJ peak force (PF) relative to body weight significantly predicted the sprint performances maximal running velocity through 10-m (V[Combining Dot Above]O2max10m) and 60-m time. The Vmax10m was also predicted by CMJ height. Jump heights from SJ and DJ did not predict sprint performances. The between-group analysis of the athletes showed a nonsignificant group difference with respect to the jump variables. However, planned comparisons between sprinters and throwers showed significant differences in a number of SLJ variables. When constructing training programs for sprinters, the aim should be to improve CMJ PF and CMJ height because of the prediction of Vmax10-m and 60-m time, presumably because of velocity specificity components.