Effect of L-arginine dietary supplementation on salivary urea concentration and pH in physically active individuals.

BACKGROUND: The aim of this study was to assess if the consumption of 3 g of a commercially available L-arginine dietary supplement causes a postabsorptive rise in urea concentration or pH of unstimulated saliva in a group of physically active individuals. METHODS: Salivary urea and pH were determined for 117 participants in a randomized double-blinded placebo-controlled study. Samples were collected by 'spitting' method in fasting conditions. One hour prior to their second visit, participants consumed three tablets of L-arginine or placebo. RESULTS: Urea concentration was significantly lower at second measurement for both the study and control group. The magnitude of the change was not significant between the groups. pH was higher for both groups at second measurement, but only significant for the study group. The magnitude of the change was significant between the groups. Participants who intermittently ingested protein dietary supplements and those with a Body Mass Index (BMI) higher than 25 had significantly higher basal urea concentration. CONCLUSIONS: The results of this study did not confirm the hypothesis. Further studies are needed to determine the effects of different doses of L-arginine supplements on the biochemical composition of saliva and the influence of their long-term consumption on the risk of developing dental diseases.

Inhibitory control of memory retrieval and motor processing associated with the right lateral prefrontal cortex: evidence from deficits in individuals with ADHD.

Studies of inhibitory control have focused on inhibition of motor responses. Individuals with ADHD consistently show reductions in inhibitory control and exhibit reduced activity of rLPFC activity compared to controls when performing such tasks. Recently these same brain regions have been implicated in the inhibition of memory retrieval. The degree to which inhibition of motor responses and inhibition of memory retrieval might involve overlapping systems has been relatively unexplored. The current study examined whether inhibitory difficulties in ADHD extend to inhibitory control over memory retrieval. During fMRI 16 individuals with ADHD and 16 controls performed the Think/No-Think (TNT) task. Behaviorally, the Stop Signal Reaction Time task (SSRT) was used to assess inhibitory control over motor responses. To link both of these measures to behavior, the severity of inattentive and hyperactive symptomatology was also assessed. Behaviorally, ADHD individuals had specific difficulty in inhibiting, but not in elaborating/increasing memory retrieval, which was correlated with symptom severity and longer SSRT. Additionally, ADHD individuals showed reduced activity in rLPFC during the TNT, as compared to control individuals. Moreover, unlike controls, in whom the correlation between activity of the rMFG and hippocampus predicts inhibitory success, no such correlation was observed for ADHD individuals. Moreover, decreased activity in rIFG in individuals with ADHD predicted a decrease in the ability to inhibit motor responses. These results suggest that inhibitory functions of rLPFC include control over both memory and motoric processes. They also suggest that inhibitory deficits in individuals with ADHD extend to the memory domain.

Relationship between intelligence and the size and composition of the corpus callosum.

We investigated the relationship between the morphology of the corpus callosum (CC) and IQ in a healthy sample of individuals in their late teens and early twenties. The relationship between the area of the CC, measured at the midline, and IQ showed regional differences. We observed that a higher estimated performance IQ was associated with smaller area in the posterior regions of the CC, a finding that differs from a positive association previously observed in a somewhat older adult sample. In contrast, higher estimated verbal IQ was associated with decreased fractional anisotropy of the genu, an anterior portion of the CC. Age effects were also observed such that older age was associated with larger CC area. Our results suggest that CC morphology is related to cognitive performance, which may have implications for clinical populations in whom CC morphology is atypical.

Effects of a new experimental training program on V.O2max and running performance.

AIM: By testing the V.O(2max) and running performance in soccer players, the purpose of the study was to determine whether an experimental conditioning program would elicit better effects than the widely used traditional program, especially across longer distances. METHODS: Laboratory measurements of maximal oxygen consumption and maximal heart rate were performed on 48 soccer players (U19) from two first league soccer teams (Experimental team, n=24; Control team n=24). Exercise intensities were calculated from heart rate maximum. Detailed training programs for both the experimental and control groups were designed for the 13-week period. The main intervention was performed in the conditioning phase where the control group performed traditional conditioning (straight-line running, with stretching exercises in the break) and the experimental group underwent a conditioning training program on designed polygon, very much akin to a real game situation; sprint-runs with or without the ball and rapid changes in direction. During the 20, 40 or 60m sprint-run the players had to perform specific ball drills depending on marked polygon station. Running performance at 60, 100, 200, 400, 800, 1200, 2 400 m distances and V.O(2max) were tested in the initial, transitory (week 6) and final trials. RESULTS: Significant improvement in 200, 400, 800, 1200, 2 400 m running performance and V.O(2max) (P<0.01), occurred in the experimental group after only 6 weeks of program and increased more after 13 weeks. Some non-significant improvement was observed in the control group at the time of the transitory trial. However, in this group the gained improvements quickly disappeared after the beginning of the competitive season as recorded at the final trial. Discriminant analysis revealed that the groups differed the most in the 200 m variable. CONCLUSION: The new experimental program is better suited for the enhancement of V.O(2max) and running performance in soccer players and the gained improvement lasted well into the competition season.

Increased occupational physical activity does not improve physical fitness.

AIM: To determine the possible influence of high physical load in the workplace on the physical fitness of employees. METHODS: The subjects (494 men) were tested by means of Baecke's questionnaire for evaluation of the Work Index, measuring occupational physical load. The EUROFIT battery of tests was used for testing the functional and motor abilities of the subjects. RESULTS: Subjects with a higher Work Index (n = 274) performed worse than the subjects with a lower Work Index (n = 220), indicating that high physical load in the workplace does not necessarily mean improvement in functional and motor abilities. The "heavy" workers were only found to have a stronger handgrip. This could be attributed to the fact that physical activity performed at the workplace did not have adequate intensity, volume, and duration to effect positive changes in other motor and functional capacities.

Body composition and functional abilities in terms of the quality of professional ballerinas.

The objective of this research was to determine the variability of the sample of professional ballerinas in the space of characteristics of their body composition and some functional characteristics according to the requirements of their roles in ballet. The sample of examinees was comprised of 30 professional ballerinas, members of the Croatian National Theatre Ballet (15 soloists and 15 members of the corps de ballet). The data showed that the soloists were characterized by a significantly larger knee diameter, significantly lower thickness of skin folds on the trunk and the lower fat body mass percentage, as well as by greater grip strength. Aerobic capacity was only moderately more developed than in fit people who participated in physical exercising because of recreational reasons, and there were no differences between soloists and the members of the corps.

Physical activity of urban adult population: questionnaire study.

AIM: To assess the level of physical activity of an urban population according to gender, age, smoking, and educational differences. METHODS: The sample comprised 594 men and women living and working in Zagreb, Croatia. Work, sport, and leisure-time activity indices were obtained by the Baecke's questionnaire. Significance of differences was tested by the Student's t-test. The relation between the indices and the education was determined by correlation analysis. RESULTS: Women had lower work and sport indices score, and higher leisure-time activity index. After the age of 50, women participated significantly more in sport activities than men. There was a negative correlation between the education and the work index, and a significantly positive correlation between the educational level and the sport activity index, regardless of gender and age. Women smokers participated to a significantly lesser extent in sport activities than women non-smokers. Such differences were not observed in men. CONCLUSION: People with lower educational level sustain more workload at their jobs than those with higher education. More educated people participate more in sport activities, although leisure time activity is not significantly related to education. In women, participation in sport activities negatively correlates with the smoking habit.

Reliability of different methods of determination of radial shortening. Influence of ulnar and palmar tilt.

Assessment of the grade of deformity after fracture of the distal end of the radius demands and accurate method of determination of radial shortening. Radiographs of 50 patients with malunited Colles' fractures were analyzed in order to find the method which is least affected by changes in ulnar and palmar tilt. Two new landmarks, the centre-point in the distal articular surface of the radius and the capitate vertex, are introduced as possible new landmarks for radial shortening determination. Results derived from commonly used methods and the new method are compared and analyzed. These show that radial shortening measured according to the commonly used landmarks is greatly affected by changes in ulnar and palmar tilt, leading to errors. Shortening measured by the two new landmarks gives results that are less influenced by rotation of the distal fragment in the frontal and sagittal planes.