Sports psychology is the measurement of mental and behavioural components that can impact on performance (Singer et al, 1993). However, sports scientists and coaches alike have a difficult task observing, measuring and controlling mental processes (Lawton, et al, 1998). One way of gaining an understanding of the brain is through Electroencephalography (EEG). An EEG records potential changes in electrical activity from electrodes on the surface of the scalp (Shelley-Tremblay, 2006). The EEG is a continuous recording of waves of various frequency and amplitude. The number of waves cycles occurring over a set period of time is it frequency with hertz (Hz) being the wave occurring over the EEG in a second.
The frequencies range from 1 to 50 Hz and the amplitudes typically range from 20 to 100uV (Neidermeyer & Lopez da Silva, 1999). Four dominant frequency ranges are typically observed: alpha (8-13Hz), beta (14-30Hz), delta (1-3 Hz) and theta (4-7Hz) (see Figure 1) however sport focuses on participants during a waking state so generally only alpha and beta waves are analysed. Alpha waves, also known as Berger rhythm, are associated with a relaxed wakefulness. Kimura and colleagues (2001) suggests an increase in alpha wave amplitude has been linked with cortical deactivation. Golf putting, pistol shooting and archery are ideal for psychophysiological data collection through EEG because participants minimize gross muscle movements and increased bioelectric activity could overwhelm the EEG recording (Shelley-Tremblay, 2006).
Various studies have examined the relationships between alpha power and performance in sport. Using golf putting, Crews et al (1998) found that successful performance was associated with low level cortical activity and agreed with earlier work of Crews & Landers (1993) and Hatfield et al (1984) who suggested that increased alpha activity was related to an increased accuracy.
The increase in alpha power in the left hemisphere suggests that the performer would be using less analytical though and less visual attention on the target (Loze et al., 2001). In a study into basketball free throws Vickers (1996) found that expert performers did not fixate their gaze during performance as much as near expert-performers and so it can be suggested that suppression of visual stimuli as a benefit to the performance of closed skills.
It would be naive to suggest that these findings would suggest it would be beneficial for athletes to not concentrate on the task to improve performance. Past research dictates that expert performers will have less thought process in the seconds prior to the shot and so have completed their analytical process to achieve competent performance. By analysing the information required to have correct performance their attention focus will narrow immediately before execution. When evaluating concentration in skilled and unskilled golfers Thomas and Over (1994) found that high handicap (lower ability) golfers claimed that they continually make adjustments to their alignment, position, grip, or swing. They were more prone to errors of judgment in their shot making and generally reported a lower level of psychomotor control.
Other sports to be used in the study of alpha power and success for sports performance are archery and pistol shooting. Jannelle et al (2000) compared alpha power across the left and right hemisphere and found significant increases in the left hemisphere for elite marksmen. However Salazar et al (1990) reported that elite marksman showed a significant increase in left hemisphere alpha power compared to right hemisphere in shots with greater error in a comparison of best and worst shots in archery.
Landers et al (1994) reported that novice archers show relatively low amounts of alpha power however with practice alpha power in the left hemisphere increases and right hemisphere remains constant. This study placed participants on a 15 week training programme and at pre-test (week 2) there were no hemispheric differences in alpha power. However at post-test (week 14) there were asymmetries in hemispheric activity as well as a 62% increase in performance. During this study additional analysis between best and worst shots were compared and the authors found that greater alpha power activity was associated with worst performance. Equivocal findings in archery were found in a best and worst shot study by Salazar (1990) however in golf Crews & Landers (1993) and Hatfield et al (1984) found an opposite effect with higher levels of alpha power being associated with best shots.
Hatfield has completed a number of studies for marksmen as they approach execution. Hatfield, Landers & Ray (1984) and Hatfield et al (1982) reported that at the moment marksmen pulled the trigger there was an increase in alpha activity in the left temporal (T3) but stability in the right temporal lobe (T4). In the later study there was additionally a general quietening of the cortex reported.
Increased alpha power being associated with best performance, was also discovered by Loze et al (2001) in air-pistol shooting. In this study the six seconds (3 x 2 second epochs) prior to execution of the shot were assessed and the highest levels of alpha power were found in the 2 seconds immediately before execution for the best shots but decreased during worst shots.
One of the general findings of EEG research is that EEG correlates show an increase in alpha power as skill level increases. However is must be identified that this does not simply mean there is cortical deactivation occurring and instead that neural reorganisation and the acquisition of more efficient motor processes is taking place (Nunez, 1995; Smith, McEvoy & Gevins, 1999).