Blood pressure and sodium intake from snacks in adolescents.

BACKGROUND/OBJECTIVES: The relationship between sodium intake and arterial blood pressure (BP) values in adolescence is still controversial. The intake of high-sodium processed foods as snacks has gone up worldwide. The purpose of the present cross-sectional study was to analyze the association between BP values and sodium intake from snacks. SUBJECTS/METHODS: The mean weekly consumption of snacks was evaluated in 1200 randomly selected adolescents aged 11-13 years by a food-frequency questionnaire; their anthropometric and BP values were measured by trained researchers. A dietary 24-h food-recall questionnaire was randomly given to 400 of the 1200 adolescents. RESULTS: Mean sodium intake from snacks was 1.4 g/day. Systolic and diastolic BP (SBP and DBP, respectively) significantly increased from the lower to the higher tertile of sodium from snacks and with increasing frequency of salty snacks consumption. In a multiple logistic regression model, both being in the highest SBP quartile and in the highest DBP quartile were significantly associated with the intake of sodium from snacks (odds ratio (OR)=1.48; 95% confidence interval (CI) 1.14-1.91 and OR=2.17; 95% CI 1.68-2.79, respectively), the consumption of >2/day salty snacks (OR=1.86; 95% CI 1.32-2.63 and OR=2.38; 95% CI 1.69-3.37, respectively) and body mass index (OR=1.26; 95% CI 1.22-1.31 and OR=1.14; 95% CI 1.10-1.18, respectively) but not with age, sex or exercise levels. In the 400 individuals, the average total sodium intake was 3.1 g/day and was significantly higher in individuals belonging to the highest quartile of SBP and DBP. CONCLUSIONS: Sodium intake from snacks was almost half of the average daily sodium consumption and was significantly associated with BP values in adolescents.

Interleukin-6 response to isokinetic exercise in elite athletes: relationships to adrenocortical function and to mechanical and myoelectric fatigue.

Exercise stimulates the release of interleukin-6 (IL-6). Aims of the study were to: (a) analyse the IL-6 response to exercise in power (n = 7) and endurance athletes (n = 13); (b) determine the effects of the IL-6 production on mechanical and myoelectric fatigue; (c) evaluate the relationship between IL-6 and adrenocortical responses. EMG variables (conduction velocity, mean power frequency, average rectified value), ACTH, cortisol, DHEA, IL-6, myoglobin, and lactate were analysed before and after an isokinetic exercise. The exercise elicited significant mechanical and myoelectric fatigue as well as significant biochemical responses. Power athletes showed IL-6 and lactate responses higher than endurance athletes. The correlation analyses showed that the greater the mechanical fatigue, the greater the increases in lactate and IL-6. No correlations were found between IL-6 and EMG variables. No relationships were found between IL-6 and cortisol, after correction for ACTH levels. In conclusion, the muscular IL-6 production, as inferred by its circulating levels, had no detectable effects on the myoelectric manifestations of fatigue and the cortisol response to exercise was not related to the amount of circulating IL-6, but only to the activation of ACTH secretion.

Effects of high-intensity isokinetic exercise on salivary cortisol in athletes with different training schedules: relationships to serum cortisol and lactate.

Physical exercise is associated with increases of serum and salivary levels of cortisol. The concomitant increase in serum lactate has been implicated as one of the mechanisms responsible for adrenocortical activation. We evaluated the responses of serum lactate and serum and salivary cortisol to an acute bout of high-intensity isokinetic exercise in eleven non-competitive and twenty competitive athletes (NCA and CA, respectively). The latter group was composed of endurance- and power-trained athletes (EA and PA, respectively). Aims of the study were to determine interindividual differences in the lactate and cortisol responses as a function of type and intensity of training and to search for relationships both between lactate and cortisol production and between serum and salivary cortisol levels. The isokinetic exercise test elicited significant cortisol and lactate responses. No difference was evident in the lactate responses between NCA and CA, while the PA showed a higher response during and after the exercise in comparison to EA (peak levels immediately after the exercise: PA 15.0 +/- 1.5 mmol/l vs. EA 11.1 +/- 2.6 mmol/l, p < 0.01). Serum cortisol was higher in the CA in comparison to the NCA group at 30 and 120 minutes after the termination of the exercise, while no differential response was evident between EA and PA groups. Salivary cortisol response was higher in the CA group in comparison to NCA immediately after the exercise and at 90 and 120 minutes after the termination and was higher in PA in comparison to EA at 60, 90, and 120 minutes after the termination (peak levels at 60 minutes: PA 51.2 +/- 18.5 nmol/l vs. EA 27.5 +/- 20.8 nmol/l, p < 0.05). No significant correlations were found between serum or salivary cortisol and lactate levels. The relationship between serum and salivary cortisol was markedly non-linear, the slope of the serum-saliva regression line being lower for serum cortisol concentrations over 500 nmol/l than for concentrations below that value (0.019 and 0.037, respectively, p < 0.01). We have confirmed in this particular setting the existence of an important adrenocortical response that can be reliably and non invasively assessed by a serial saliva sampling and have supported the concept that cortisol and lactate responses to a high-intensity isokinetic exercise are independent. The interindividual differences in cortisol changes are likely to be related to the training status and mode as well as to the correspondence between the evaluation protocol and the discipline individually performed.

Isokinetic testing of flexor and extensor muscles in athletes suffering from low back pain.

BACKGROUND: The aim of the study was to verify the usefulness of isokinetic testing in athletes with chronic low back pain (LBP) to obtain quantitative information for rehabilitation purposes. EXPERIMENTAL DESIGN: a comparative study. SETTING: Physiotherapy Department--Institute of Sports Medicine in Italy. PARTICIPANTS: 50 men, aged 25-65, practising running, cycling, triathlon, tennis, soccer, basketball, volleyball, skiing and golf. The patients were divided into two groups. Group A was treated for 3 months with postural exercises 2 or 3 times a week. Group B was treated for the same period of time with resistive exercises performed by resorting to specific machines. MEASUREMENTS: Before and after treatment, trunk muscle strength was evaluated by means of an isokinetic test carried out in a seated position. The isokinetic measurements used were peak torque (PT), work, power-in the best repetition and total work (TW) in four repetitions. Both the pain and the functional impairment during physical activity was evaluated by subjective visual analogic scale. RESULTS: The PT showed a parallel increase in flexor and extensor muscles in Group A. In Group B it increased by 32.2% at 60 degrees/s and 44.1% at 120 degrees/s as for the extensor muscles while the flexion-to-extension ratio decreased significantly. The TW registered a bigger percentage increase in both groups (+21% at 60 degrees/s and +20.4% at 120 degrees/s in Group A; +36.5% at 60 degrees/s and +50.3% at 120 degrees/s in Group B). CONCLUSIONS: The two rehabilitation programmes had the same effect on the course of LBP, but in Group B we observed a bigger increase in strength which could be potentially useful during a sports activity.

Hematological status in a group of male athletes of different sports.

Suboptimal hematological status has been often recorded in athletes involved in intense physical activity, particularly in middle and long distance runners. It appeared therefore interesting the study and comparison of athletes groups of different sports. One hundred eighty-one male athletes were tested and divided into seven groups according to sport exercise: cross-country skiing, cycling, fencing and tennis (joined together), rowing, running, soccer, swimming. For every athletes erythrocyte and hemoglobin blood concentration, hematocrit, serum iron, transferrin, ferritin and haptoglobin concentration were measured, the mean cell volume and serum iron/transferrin ratio were calculated. Data were compared to find out correlation indices and then grouped according to the practised sport. Statistical indices were computed for each group and for all parameter and analysis of variance was carried out to value the significativity of found differences. The only parameter showing statistically significant differences among groups was the serum level of haptoglobin, with mean value significantly lower in runners. The evidence of this study suggests that individual variability for the remaining parameters exceeds any variation possibly induced by different sport practices.

Effects of L-carnitine administration on VO2max and the aerobic-anaerobic threshold in normoxia and acute hypoxia.

Seven healthy young male adults were subjected to a total of 56 tests to ascertain the effects of L-carnitine (L-C) and a placebo (P) on ventilation, O2 intake (VO2), CO2 output, heart rate, blood pressure and serum lactic acid, non-esterified fatty acid, glycerol and glucose during strenuous and aerobic/anaerobic threshold-level treadmill exercise. The tests were made in conditions of normoxia (O2 = 20.9%) and hypoxia (O2 = 13.0%, equivalent to 3,500 m above sea level). The only clear difference was in the respiratory quotient (RQ = 0.883, SD 0.025 vs 0.904, SD 0.035) after L-C and P administration respectively (P less than 0.01), under normal oxygenation and 0.861, SD 0.052 following L-C vs 0.926, SD 0.040 after P (P less than 0.01) in acute hypoxia at VO2 levels around the anaerobic threshold. The lower RQ values of the L-C-treated subjects during hypoxia indicate a lower rate of carbohydrate transformation.