Ecological validity in exercise neuroscience research: A systematic investigation.

The contribution of cortical processes to adaptive motor behaviour is of great interest in the field of exercise neuroscience. Next to established criteria of objectivity, reliability and validity, ecological validity refers to the concerns of whether measurements and behaviour in research settings are representative of the real world. Because exercise neuroscience investigations using mobile electroencephalography are oftentimes conducted in laboratory settings under controlled environments, methodological approaches may interfere with the idea of ecological validity. This review utilizes an original ecological validity tool to assess the degree of ecological validity in current exercise neuroscience research. A systematic literature search was conducted to identify articles investigating cortical dynamics during goal-directed sports movement. To assess ecological validity, five elements (environment, stimulus, response, body and mind) were assessed on a continuum of artificiality-naturality and simplicity-complexity. Forty-seven studies were included in the present review. Results indicate lowest average ratings for the element of environment. The elements stimulus, body and mind had mediocre ratings, and the element of response had the highest overall ratings. In terms of the type of sport, studies that assessed closed-skill indoor sports had the highest ratings, whereas closed-skill outdoor sports had the lowest overall rating. Our findings identify specific elements that are lacking in ecological validity and areas of improvement in current exercise neuroscience literature. Future studies may potentially increase ecological validity by moving from reductionist, artificial environments towards complex, natural environments and incorporating real-world sport elements such as adaptive responses and competition.

Decoupling of laxity and cortical activation in functionally unstable ankles during joint loading.

PURPOSE: Recent studies have highlighted central nervous system alterations following ligamentous injury that may contribute to joint instability. However, research has not observed cortical responses to joint loading or sensory changes in the context of joint laxity following injury. METHODS: Forty-two subjects were stratified into healthy (CON), unstable (UNS), and coper (COP) groups using ankle injury and instability history. Event-related desynchronization (%) from electroencephalography quantified somatosensory cortex activity as the ankle was loaded using an arthrometer. RESULTS: Cortical activation increased as the ankle was loaded (F = 63.05, p < 0.001), but did not differ between groups (F = 1.387, p = 0.268), despite greater laxity in UNS (F = 3.58, p = 0.038). CONCLUSIONS: Increased somatosensory cortex activity was observed with joint loading; however, though UNS demonstrated a degree of mechanical instability, no differences in magnitude of cortical activation were observed. Continued research should explore how the relationship between cortical activation and joint stiffness is affected following ligamentous injury.

Effects of induced fatigue on brain activity during sensorimotor control.

The aim of this study was to study if accuracy in sensorimotor control and cortical activity was influenced after induced fatigue during a knee joint reproduction task. Twelve volunteers performed a sensorimotor task before, directly after and 60 min after a prolonged exhaustive exercise protocol. The task consisted of an active reproduction of a target knee angle. After three practice trials, visual feedback was taken and the task was performed for 10 repetitions at a suitable pace. Reproduction accuracy was analyzed and EEG raw data were obtained from the frontal, central, temporal, parietal and occipital scalp locations during the task. The average power spectra in theta and alpha frequencies were computed across conditions for each participant. Task accuracy decreases significantly related to fatigue and increases after recovery. This is accompanied by a significant decrease in frontal theta, alpha-1 and alpha-2 frequencies after inducing fatigue. The power values in all frequency bands recovered after 60 min. Sensorimotor control was influenced by induced fatigue, which could be demonstrated in behavior and brain activity. Characteristics of brain activity demonstrated an increase in theta and a decrease in alpha-1 and alpha-2 frequency band power. The changes were discussed related to attentional recourses, alertness and somatosensory information processing mechanisms.

From lab to field conditions: a pilot study on EEG methodology in applied sports sciences.

Although neurophysiological aspects have become more important in sports and exercise sciences in the last years, it was not possible to measure cortical activity during performance outside a laboratory due to equipment limits or movement artifacts in particular. With this pilot study we want to investigate whether Electroencephalography (EEG) data obtained in a laboratory golf putting performance differ from a suitable putting task under field conditions. Therefore, parameters of the working memory (frontal Theta and parietal Alpha 2 power) were recorded during these two conditions. Statistical calculations demonstrated a significant difference only for Theta power at F4 regarding the two putting conditions "field" and "laboratory". These findings support the idea that brain activity patterns obtained under laboratory conditions are comparable but not equivalent to those obtained under field conditions. Additionally, we were able to show that the EEG methodology seems to be a reliable tool to observe brain activity under field conditions in a golf putting task. However, considering the still existing problems of movement artifacts during EEG measurements, eligible sports and exercises are limited to those being relatively motionless during execution. Further studies are needed to confirm these pilot results.

Altered electrocortical brain activity after ACL reconstruction during force control.

Afferent proprioceptive information from the knee joint may be altered due to a reconstruction of the anterior cruciate ligament (ACL), which could result in changes of cortical activity. The aim of the study is to look if force sensation and cortical activation measured by EEG are influenced by an ACL-reconstruction when performing a force reproduction task. Nine patients after ACL reconstruction and nine healthy controls were asked to reproduce 50% of their maximal voluntary isometric contraction (MVIC) reproduction. EEG power values related to frequency bands and the error in reproduction were collected while performing the force reproduction. The aberration error demonstrated no significant differences between groups. The cortical activity results in significant higher frontal Theta power during the force reproduction task with the reconstructed limb (F3 and Fz: p < 0.05) of the ACL group compared to the controls. The EEG was able to measure changes in electrocortical activity after ACL-reconstruction in force reproduction, whereas performance data was not affected. The results were discussed in terms of differences in attentional control with involvement of the anterior cingulate cortex related to higher frontal Theta power in the ACL patients.

Brain activity in goal-directed movements in a real compared to a virtual environment using the Nintendo Wii.

Low budget virtual environments like the Nintendo Wii increased in popularity and may play a role in motor learning related to sports and exercise. But nothing was known about the comparability of cortical activity of motor tasks in real and virtual environments. The aim of the study was to examine cortical differences between real and Wii based virtual sports performances using the golf putt as a model. Ten male golfers (26.0 +/- 0.7 years; 81.8 +/- 5.6 kg; 184.5 +/- 6.0 cm; handicap 30.0+/-10.0; 2.9+/-1.0 years of golf experience) were asked to putt for 3 min in random order in the real and the virtual Wii condition. A rest in sitting position (3 min) followed each performance. The score and cortical activity (EEG) were recorded continuously. The participants performed with a significant better score in the real condition (p < or = 0.01). Compared to virtual putting Theta spectral power showed a significant increase during real performance at F3 and F4 (p < or = 0.05). Significantly increased Alpha-2 power was demonstrated during real putting compared to the virtual putting performance at P3 (p < or = 0.05). The findings suggested that putting performance and brain activity was influenced by the choice of a real or virtual environment. The results were discussed based on the concept of the working memory where increased frontal Theta power indicated higher focused attention and higher Alpha-2 power was inversely related to the quantity of sensory information processing in the real putting compared to the virtual condition.

Cortical activity of skilled performance in a complex sports related motor task.

A skilled player in goal-directed sports performance has the ability to process internal and external information in an effective manner and decide which pieces of information are important and which are irrelevant. Focused attention and somatosensory information processing play a crucial role in this process. Electroencephalographic (EEG) recordings are able to demonstrate cortical changes in conjunction with this concept and were examined during a golf putting performance in an expert-novice paradigm. The success in putting (score) and performance-related cortical activity were recorded with an EEG during a 5 x 4 min putting series. Subjects were asked to putt balls for four min at their own pace. The EEG data was divided into different frequencies: Theta (4.75-6.75 Hz), Alpha-1 (7-9.5 Hz), Alpha-2 (9.75-12.5 Hz) and Beta-1 (12.75-18.5 Hz) and performance related power values were calculated. Statistical analysis shows significant better performance in the expert golfers (P < 0.001). This was associated with higher fronto-midline Theta power (P < 0.05) and higher parietal Alpha-2 power values (P < 0.05) compared to the novices in golf putting. Frontal Theta and parietal Alpha-2 spectral power in the ongoing EEG demonstrate differences due to skill level. Furthermore the findings suggest that with increasing skill level, golfers have developed task solving strategies including focussed attention and an economy in parietal sensory information processing which lead to more successful performance. In a theoretical framework both cortical parameters may play a role in the concept of the working memory.