Cued motor imagery in patients with multiple sclerosis

Motor imagery (MI) is a promising practice tool in neurorehabilitation. However, in patients with multiple sclerosis (MS), impairments in MI accuracy and temporal organization were found during clinical assessment, which may limit the benefits of MI practice. Therefore, we investigated whether the MI quality of MS patients could be optimized by means of external cueing. Fourteen patients with MS and 14 healthy control patients physically executed and visually imagined a goal-directed upper limb task in the presence and absence of added visual and auditory cues. MI quality was assessed by means of eye-movement registration. As main results, it was found that MS patients had significant higher eye-movement times than controls during both execution and imagery, and overestimated the to-be-imagined movement amplitude when no external information was provided during imagery. External cues, however, decreased patients' MI duration and increased the spatial accuracy of their imagined movements. In sum, our results indicate that MS patients imagine movements in a better way when they are provided with external cues during MI. These findings are important for developing rehabilitation strategies based on MI in patients with MS.

Echocardiographic study of structure and functional cardiac profile of football referees

AIM

The aim of this study was to analyze, through echocardiography, the structure and functional cardiac profile of national category Spanish soccer referees.

METHODS

The sample consisted of 54 licensed referees, who belonged to the Football Inter-Insular Federation of Las Palmas. The sample presented a mean age of 28.52 ± 6.39 years, a height of 1.76 ± 0.07 m, a body mass of 77.26 ± 10.74 kg and a Body Mass Index of 24.90 ± 2-73 kg/m2. The diastolic and systolic dimensions of the left ventricle were 50.03 ± 4.79 mm and 33.74 ± 5.23 mm, respectively. The thicknesses of the interventricular septum and the posterior wall of the left ventricle were 9.77 ± 1.53 mm and 9.47 ± 1.54 mm, respectively. The left ventricular mass was 112.80 ± 26.53 g/m2, the diastolic volume of the left ventricle 135.09 ± 39.63 mL and the ejected volume 47.34 ± 12.44 mL/m2.

RESULTS

This study shows that the echocardiographic profile of football referees is characterized by presenting an increase in the left ventricular mass caused by an increase of the cardiac chambers and a normal systolic and diastolic function. The values obtained by football referees were higher than those found in sedentary people and lower than in professional football players.

CONCLUSION

These differences may be due to the different physical training workloads employed by football players and referees.

Physical demands of top-class soccer assistant refereeing during high-standard matches

This study examined the physical demands experienced by top-class assistant referees during high-standard football matches. Computerized match analyses and heart rate recordings were performed on 18 international assistant referees during the FIFA Confederations Cup 2005. Total distance covered averaged 5752+/-554 m, of which 34% was covered at a high-intensity (>13 km.h (-1)). Sidewards movements represented 30% of total match distance. Both total distance (r=0.67; P<0.01) and high-intensity activities (r=0.52; P<0.05) were related to the displacements of the ball in the same match. The distance covered by high-speed running in this tournament was 255% greater (P<0.001) than that covered during the under-17 World Championship 2003. Mean heart rate during the game was 140+/-11 b.min (-1) (78+/-4% HR (max)). Mean heart rate during a 5-min interval of the match was related in part (r=0.31; P<0.001) to the amount of high-intensity activities performed within the same match-period. The results of this study show that the physical demands imposed on assistant referees are influenced by the movements of the ball and the standard of the competition.

Injuries and musculoskeletal complaints in referees and assistant referees selected for the 2006 FIFA World Cup: retrospective and prospective survey

BACKGROUND

There is a considerable amount of scientific literature on football, but few studies have focused on referees, despite their key role in this sport. Existing studies focus on the physiological demands and training of referees.

PURPOSE

To analyse injuries and musculoskeletal complaints in referees and assistant referees selected for the 2006 FIFA World Cup.

STUDY DESIGN

Retrospective survey and prospective study.

METHODS

During the preparation camps for the 2006 FIFA World Cup in Germany, all 123 referees pre-selected for the tournament completed a questionnaire on injuries and musculoskeletal complaints. During the tournament, the characteristics and consequences of all injuries and complaints incurred by the 63 officiating referees were documented.

RESULTS

More than 40% of the referees reported having incurred an injury and more than 60% having had musculoskeletal complaints during their career. About 20% of the group reported having suffered from musculoskeletal complaints in the last match. During the World Cup, 14 referees (22%) incurred an injury and more than 30% had musculoskeletal complaints. This prospectively collected data showed an incidence of 20.8 injuries per 1000 match hours (95% CI: 4.17 to 37.4). The most common acute injuries were hamstring strains, calf strains, and ankle sprains, while the most frequent locations of complaints were the low back, hamstring and knee.

CONCLUSION

Considering the injury profile, the prevalence of associated musculoskeletal complaints, and the high physiological demands of refereeing, it appears that injury prevention programmes should be developed and integrated into the fitness training routine of the referee.

The effect of match standard and referee experience on the objective and subjective match workload of English Premier League referees

The aim of the present study was to examine the effect of match standard and referee experience on the objective and subjective workload of referees during English Premier League and Football League soccer matches. We also examined the relationship between heart rate (HR) and ratings of perceived exertion (RPE) for assessing match intensity in soccer referees. Heart rate responses were recorded using short-range telemetry and RPE scores were collected using a 10-point scale. Analysis revealed a significant relationship between mean match HR and match RPE scores (r=0.485, p<0.05, n=18). There were significant differences in match HR (Premier League 83.6+/-2.6% maximal HR (HRmax) versus Football League 81.5+/-2.2%HRmax, p<0.05) and match RPE scores (Premier League 7.8+/-0.8 versus Football League 6.9+/-0.8, p<0.05) between standards of competition. Referee experience had no effect on match HR and RPE responses to Premier League and Football League matches. The results of the present study demonstrate the validity of using HR and RPE as a measure of global match intensity in soccer referees. Referee experience had no effect on the referees' objective and subjective match workload assessments, whereas match intensity was correlated to competition standard. These findings have implications for fitness preparation and evaluation in soccer referees. When progressing to a higher level of competition, referees should ensure that appropriate levels of fitness are developed in order to enable them to cope with an increase in physical match demands.

Effects of peripheral cooling on intention tremor in multiple sclerosis

OBJECTIVE

To investigate the effect of peripheral sustained cooling on intention tremor in patients with multiple sclerosis (MS). MS induced upper limb intention tremor affects many functional activities and is extremely difficult to treat.Materials/

METHODS

Deep (18 degrees C) and moderate (25 degrees C) cooling interventions were applied for 15 minutes to 23 and 11 tremor arms of patients with MS, respectively. Deep and moderate cooling reduced skin temperature at the elbow by 13.5 degrees C and 7 degrees C, respectively. Evaluations of physiological variables, the finger tapping test, and a wrist step tracking task were performed before and up to 30 minutes after cooling.

RESULTS

The heart rate and the central body temperature remained unchanged throughout. Both cooling interventions reduced overall tremor amplitude and frequency proportional to cooling intensity. Tremor reduction persisted during the 30 minute post cooling evaluation period. Nerve conduction velocity was decreased after deep cooling, but this does not fully explain the reduction in tremor amplitude or the effects of moderate cooling. Cooling did not substantially hamper voluntary movement control required for accurate performance of the step tracking task. However, changes in the mechanical properties of muscles may have contributed to the tremor amplitude reduction.

CONCLUSIONS

Cooling induced tremor reduction is probably caused by a combination of decreased nerve conduction velocity, changed muscle properties, and reduced muscle spindle activity. Tremor reduction is thought to relate to decreased long loop stretch reflexes, because muscle spindle discharge is temperature dependent. These findings are clinically important because applying peripheral cooling might enable patients to perform functional activities more efficiently.

Eye-hand coordination in goal-directed aiming

In a number of studies, we have demonstrated that the spatial-temporal coupling of eye and hand movements is optimal for the pickup of visual information about the position of the hand and the target late in the hand's trajectory. Several experiments designed to examine temporal coupling have shown that the eyes arrive at the target area concurrently with the hand achieving peak acceleration. Between the time the hand reached peak velocity and the end of the movement, increased variability in the position of the shoulder and the elbow was accompanied by a decreased spatial variability in the hand. Presumably, this reduction in variability was due to the use of retinal and extra-retinal information about the relative positions of the eye, hand and target. However, the hand does not appear to be a slave to the eye. For example, we have been able to decouple eye movements and hand movements using Müller-Lyer configurations as targets. Predictable bias, found in primary and corrective saccadic eye movements, was not found for hand movements, if on-line visual information about the target was available during aiming. That is, the hand remained accurate even when the eye had a tendency to undershoot or overshoot the target position. However, biases of the hand were evident, at least in the initial portion of an aiming movement, when vision of the target was removed and vision of the hand remained. These findings accent the versatility of human motor control and have implications for current models of visual processing and limb control.

Temporal and spatial adaptations during the acquisition of a reversal movement

Adjustments of the biphasic movement in a coincidence anticipation task were studied using an erroneous knowledge of results (KR) paradigm. Forty participants received either no KR, correct KR, erroneous (+100 ms) KR, or 100 trials of correct KR followed by 50 trials of erroneous KR. Kinematic analyses revealed that for this 100-50 KR group the extension part of the movement was temporally adjusted under the influence of erroneous KR. Although accompanied by a decrease in movement amplitude, this did not account for the temporal shift in movement outcome, because all groups showed a reduction in amplitude. It is argued that changing external time constraints mainly results in temporal adaptations. However, spatial adaptations do play a role in kinematic changes during acquisition.