Maximum Phonation Time as a Predictor of Lactate Threshold during Intermittent Incremental Endurance Test.

The aim of the present study was to examine whether the exercise intensity corresponding to the lactate threshold may be predicted by the Maximum Phonation Time task (MPT). Ten Greek amateur football players (age: 18.4 ± 1.0 years), performed a graded cycling exercise test to exhaustion in order to determine lactate threshold. A number of physiological variables were measured including perceived exertion, cardiopulmonary values and blood lactate. The MPT variable was correlated with all of the physiological variables. Also, a binary logistic regression analysis was used to investigate whether MPT could predict lactate threshold. The ROC analysis showed specificity to be 0.90 and sensitivity to be 0.70 (optimal screening cutoff point for MPT 9.5 seconds). The results showed an odds ratio of 1.45 indicating a 45% increase in the probability of passing the threshold for every second there was a reduction in voice duration. MPT may be used as a simple, non-invasive, inexpensive method for monitoring exercise intensity during physical exercise. Further research is needed to measure its efficacy in bigger samples and in different sports.

Adaptations to endurance training depend on exercise-induced oxidative stress: exploiting redox interindividual variability.

AIM: The aim of this study was to reveal the role of reactive oxygen and nitrogen species (RONS) in exercise adaptations under physiological in vivo conditions and without the interference from other exogenous redox agents (e.g. a pro-oxidant or antioxidant). METHODS: We invented a novel methodological set-up that exploited the large redox interindividual variability in exercise responses. More specifically, we used exercise-induced oxidative stress as the 'classifier' measure (i.e. low, moderate and high) and investigated the physiological and redox adaptations after a 6-week endurance training protocol. RESULTS: We demonstrated that the group with the low exercise-induced oxidative stress exhibited the lowest improvements in a battery of classic adaptations to endurance training (VO2 max, time trial and Wingate test) as well as in a set of redox biomarkers (oxidative stress biomarkers and antioxidants), compared to the high and moderate oxidative stress groups. CONCLUSION: The findings of this study substantiate, for the first time in a human in vivo physiological context, and in the absence of any exogenous redox manipulation, the vital role of RONS produced during exercise in adaptations. The stratification approach, based on a redox phenotype, implemented in this study could be a useful experimental strategy to reveal the role of RONS and antioxidants in other biological manifestations as well.

Reductive stress after exercise: The issue of redox individuality.

Exercise has been consistently used as an oxidant stimulus in redox biology studies. However, previous studies have focused on group differences and did not examine individual differences. As a result, it remains untested whether all individuals experience oxidative stress after acute exercise. Therefore, the main aim of the present study was to investigate whether some individuals exhibit unexpected responses after an acute eccentric (i.e., muscle-damaging) exercise session. Ninety eight (N = 98) young men performed an isokinetic eccentric exercise bout with the knee extensors. Plasma, erythrocytes and urine samples were collected immediately before and 2 days post-exercise. Three commonly used redox biomarkers (F2-isoprostanes, protein carbonyls and glutathione) were assayed. As expected, the two oxidant biomarkers (F2-isoprostanes and protein carbonyls) significantly increased 2 days after exercise (46% and 61%, respectively); whereas a significant decrease in glutathione levels (by -21%) was observed after exercise. A considerable number of the participants exhibited changes in the levels of biomarkers in the opposite, unexpected direction than the group average. More specifically, 13% of the participants exhibited a decrease in F2-isoprostanes and protein carbonyls and 10% of the participants exhibited an increase in glutathione levels. Furthermore, more than 1 out of 3 individuals exhibited either unexpected or negligible (from 0% to ± 5%) responses to exercise in at least one redox biomarker. It was also observed that the initial values of redox biomarkers are important predictors of the responses to exercise. In conclusion, although exercise induces oxidative stress in the majority of individuals, it can induce reductive stress or negligible stress in a considerable number of people. The data presented herein emphasize that the mean response to a redox stimulus can be very misleading. We believe that the wide variability (including the cases of reductive stress) described is not limited to the oxidant stimulus used and the biomarkers selected.

No adverse effects of statins on muscle function and health-related parameters in the elderly: an exercise study.

The aim of the present study was to investigate the effects of a repeated bout of eccentric exercise on health-related parameters and muscle performance on subjects undergoing atorvastatin therapy. Twenty-eight elderly men participated in the investigation and were assigned either in a control (n = 14) or in a statin therapy group (n = 14). All participants performed two isokinetic eccentric exercise bouts separated by 3 weeks. Muscle damage indices, resting energy expenditure, substrate metabolism, lipid and lipoprotein profile, as well as insulin sensitivity, were evaluated before and after eccentric. No differences in muscle function were observed between the two groups either at rest or after exercise. Eccentric exercise increased resting energy expenditure, increased fat oxidation, improved lipid profile, and increased insulin resistance 2 days after both eccentric exercise bouts. However, these changes appeared to lesser extent after the second bout. No differences were observed in the responses in the health-related parameters in the control and in the statin therapy group. Eccentric exercise affected similarly the control and the atorvastatin-treated individuals. The present results indicate that atorvastatin-treated elderly individuals may participate in various physical activities, even high-intensity muscle-damaging activities, without negative impact on muscle function and adaptation.

Overweight and obesity in preadolescent children and their parents in Cyprus: prevalence and associated socio-demographic factors - the CYKIDS study.

Obesity status differs by socio-demographic factors, but data for Cyprus are scarce. An in-depth understanding of this relationship may be useful in designing public health programmes. The objective of the present study is to estimate overweight and obesity (OW/OB) prevalence among children and adults in Cyprus and identify related socio-demographic variables. National cross-sectional study of 1140 children (mean age 11 +/- 0.98 years) and their parents (mean age 42.5 +/- 5.8 years, total n = 1954). Obesity was defined according to the World Health Organization classification for adults and according to IOTF (International Obesity Task Force) criteria for children. Overweight and obesity prevalence among girls was 18.3% and 2.9%, respectively, while in boys, 19.0% and 6.0%. Among parents, OW/OB prevalence was, respectively, women, 22.6% and 5.8%; men, 47.1% and 14.1%. Logistic regression analysis in both children and adults revealed that the most important socio-demographic predictors of obesity status are factors of built environment. Higher prevalence of OW/OB was observed in adults living in a house as opposed to an apartment, in older adults, in younger children, and in men, irrespective of age. There is a severe obesity problem in the Cypriot population; almost one in two adults and at least one in four preadolescent children are overweight or obese. Prevalence of OW/OB was related to socio-demographic factors, especially among adults and women.

Effect of self-focused attention on the startle reflex, heart rate, and memory performance among socially anxious and nonanxious individuals.

The present study examined the effect of self-focused attention on the startle reflex and heart rate and assessed the assumption that socially anxious individuals become self-focused in evaluative situations. Twenty-five high and 30 low socially anxious men performed a digit recall task under evaluative or nonevaluative instructions. Half of the trials were performed under self-focused conditions and half under non-self-focused conditions. Self-focus led to larger startle responses among socially anxious individuals and had no effect on heart rate. Self-focus combined with evaluation led to poorer recall performance among all subjects. Results provide evidence against a directional change in attention during self-focused attention and favor the view that self-focus increases access to self-relevant thought content and decreases available processing resources.