The effects of exercise, heat, cooling and rehydration strategies on cognitive function in football players

We investigated the cognitive effects of exercising in the heat on the field players of two football teams in a series of three matches. Different rehydration and cooling strategies were used for one of the teams during the last two games. Cognitive functions were measured before, during and immediately after each football match, as well as core temperature, body mass, plasma osmolality and glucose levels, allowing an estimate of their differential impacts on cognition. The pattern of results suggests that mild-moderate dehydration during exercise in the heat (up to 2.5%) has no clear effect on cognitive function. Instead, plasma glucose and core temperature changes appear to be the main determinants: higher glucose was related to faster and less accurate performance, whereas core temperature rises had the opposite effect. The 50% correlation between plasma glucose and core temperatures observed during exercise in the heat may help to stabilize cognitive performance via their opposing effects. The glucose-like effects of sports drinks appear to be mediated by increased plasma glucose levels, because drinks effects became non-significant when plasma glucose levels were added to the models. The cooling intervention had only a beneficial effect on complex visuo-motor speed.

Effect of pulsed magnetic field on regenerating rat sciatic nerve: An in-vitro electrophysiologic study

Some experimental studies report that low-frequency pulsed electromagnetic field (PEMF) stimulation may accelerate regeneration in peripheral nerves. In the present study, effects of PEMF on the regeneration of the crushed rat sciatic nerves were investigated with histological and in-vitro electrophysiological methods (sucrose-gap). After crush injury of the sciatic nerves, rats were divided into 5, 15, 25, 38 day-groups and exposed to PEMF (1.5 h/day, intensity; 1.5 mT, consecutive frequency; 10-40-100 Hz). In the 15th day post crush, compound action potential (CAP) amplitude was measured as 5.5+/-1 mV (crush group) and 5.4+/-1.2 mV (crush+PEMF group). In addition, half width of CAP extended ~3 fold in both groups and frequency-dependent amplitude inhibition (FDI) decreased approximately 20% at 100 Hz. In the 38th day, amplitude of CAP, half width of CAP and FDI were measured nearly intact nerve values in both groups. In histological examinations, Wallerian degeneration was observed similar progress between both groups. The results were compared between crush and crush + PEMF groups, it was found that the effect of PEMF was not significant. The authors conclude that PEMF were ineffective on rat sciatic nerve regeneration.

Analysis of isokinetic knee extension / flexion in male elite adolescent wrestlers

Wrestling requires strength of the upper and lower body musculature which is critical for the athletic performance. Evaluation of the adolescent's skeletal muscle is important to understand body movement, especially including those involved in sports. Strength, power and endurance capacity are defined as parameters of skeletal muscle biomechanical properties. The isokinetic dynamometer is an important toll for making this type of evaluation. However, load range phase of range of motion has to be considered to interpret the data correctly. With this in mind we aimed to investigate the lover body musculature contractile characteristics of adolescent wrestlers together with detailed analyses of load range phase of motion. Thirteen boys aged 12 - 14 years participated to this study. Concentric load range torque, work and power of knee extension and flexion were measured by a Cybex Norm dynamometer at angular velocities from 450°/sec to 30°/sec with 30°/sec decrements for each set. None of the wrestlers were able to attain load range for angular velocities above 390°/sec and 420°/sec for extension and flexion respectively. Detailed analyses of the load range resulted in statistically significant differences in the normalized load range peak torque for extension at 270°/sec (1.44 ± 0.28 Nm·kg(-1) and 1.14 ± 0.28 Nm·kg(-1) for total and load range peak torque respectively, p < 0.05), and for flexion at 300°/sec (1.26 ± 0.28 Nm·kg(-1) and 1.03 ± 0.23 Nm·kg(-1) for total and load range peak torque respectively, p < 0.05), compared to total peak torque data. Similarly, the significant difference was found for the work values at 90°/sec (1.91 ± 0.23 Nm·kg(-1) and 1.59 ± 0.24 Nm·kg(-1) for total and load range work respectively for extension and 1.73 ± 0.21 Nm·kg(-1) and 1.49 ± 0.19 Nm·kg(-1) for total and load range work respectively for flexion, p < 0.05), and was evident at higher angular velocities (p < 0.001) for both extension and flexion. At extension, load range power values were significantly smaller than total power for all angular velocities except 150°/sec (p < 0.05 for 120 and 180°/sec, p < 0.001 for others). Finally, load range flexion power was found to be higher than total power with statistically significance (p < 0.05 for 60, 120, 150, 180, 210, 270 and 300°/sec, p < 0.001 for 240 °/sec). Extra caution is required for correct interpretation of load range data in terms of considering the load range during limb movement. Evaluation of muscle performance of these adolescent wrestlers at regular intervals may give us an opportunity to obtain a healthy maturation profile of these adolescent wrestlers. Key PointsConsideration of load range for peak torque, work and power calculation resulted significant differences in the data presented by isokinetic dynamometer. Therefore evaluation of the dynamometer data required consideration of the load range for correct analysis and interpretation.Contraction velocity has critical importance in determining the load range attaining ability for a moving limb during load range evaluation. In fact alterations in contraction speed may be due to a number of changes in muscle morphology, subjects' age and the ratio between type I and type II muscle fiber area.

Conduction blocks of lidocaine on crushed rat sciatic nerve: an in-vitro study

The effects of lidocaine on the action potential of crushed sciatic nerves were investigated. The sciatic nerves of the rats were removed 5, 15, 25, and 38 days after the crushing and the compound action potentials were recorded with sucrose gap technique. The nerves were treated with 1 mM lidocaine and the conduction blocks of nonfrequency dependent block (NFDB) and frequency depended block (FDB) at 10, 40, and 100 Hz were determined. In intact nerves, the NFDB effect of lidocaine was 38.4 +/- 0.7 %. On the 15th day after the crush, the NFDB was increased to 60.1 +/- 1.3%. On the 38th day NFDB was decreased to 46.0 +/- 0.8%. The following days after the crushing, lidocaine caused a very high rate of FDB with 10, 40, and 100 Hz stimulation. The high NFDB ratios approached normal levels with the improvement of regeneration, but FDB ratios continued to stay at high levels. The results showed that the ratios of FDB and NFDB were increased on the crushed nerve. It was concluded that, in the regeneration conditions of crushed rat sciatic nerves, the sensitivity to local anesthetic increases more than in intact nerves.