Sascha Härtel

Impact of aerobic exercise training on cognitive functions and affect associated to the COMT polymorphism in young adults

Physical fitness can serve as a means to enhance cognitive functioning by modulating particular aspects of brain functioning. However, mechanisms underlying this modulating effect remain widely unresolved. To examine the impact and to clarify the mechanisms of physical fitness training in a young and healthy population, it was investigated whether an increase in fitness would result in improvements in executive control processes and positive and negative affect. Moreover, genotype of the Val158Met polymorphism in catechol-O-methyltransferase (COMT) as an index of relative central dopamine bioavailability was determined to elucidate dopamine tuning efficiency and its association with performance in the applied cognitive tasks. Seventy-five individuals participated and underwent an incremental fitness test to assess physical fitness. An exercising group subsequently engaged in a 17 weeks running training consisting of three running sessions at moderate to high, individually adjusted intensities. Associated with increased fitness improved cognitive flexibility and cognitive control were observed, whereas working memory remained unaffected. In runners, Val/Val participants improved cognitive performance to a greater extent compared to individuals carrying a Met allele. From the present results it is concluded that an increase in physical fitness provides a means to improve cognitive functioning via dopaminergic modulation.

Validation and comparison of two methods to assess human energy expenditure during free-living activities.

Background The measurement of activity energy expenditure (AEE) via accelerometry is the most commonly used objective method for assessing human daily physical activity and has gained increasing importance in the medical, sports and psychological science research in recent years. Objective The purpose of this study was to determine which of the following procedures is more accurate to determine the energy cost during the most common everyday life activities; a single regression or an activity based approach. For this we used a device that utilizes single regression models (GT3X, ActiGraph Manufacturing Technology Inc., FL., USA) and a device using activity-dependent calculation models (move II, movisens GmbH, Karlsruhe, Germany). Material and Methods Nineteen adults (11 male, 8 female; 30.4±9.0 years) wore the activity monitors attached to the waist and a portable indirect calorimeter (IC) as reference measure for AEE while performing several typical daily activities. The accuracy of the two devices for estimating AEE was assessed as the mean differences between their output and the reference and evaluated using Bland-Altman analysis. Results The GT3X overestimated the AEE of walking (GT3X minus reference, 1.26 kcal/min), walking fast (1.72 kcal/min), walking up−/downhill (1.45 kcal/min) and walking upstairs (1.92 kcal/min) and underestimated the AEE of jogging (−1.30 kcal/min) and walking upstairs (−2.46 kcal/min). The errors for move II were smaller than those for GT3X for all activities. The move II overestimated AEE of walking (move II minus reference, 0.21 kcal/min), walking up−/downhill (0.06 kcal/min) and stair walking (upstairs: 0.13 kcal/min; downstairs: 0.29 kcal/min) and underestimated AEE of walking fast (−0.11 kcal/min) and jogging (−0.93 kcal/min). Conclusions Our data suggest that the activity monitor using activity-dependent calculation models is more appropriate for predicting AEE in daily life than the activity monitor using a single regression model.

Hormonal, metabolic, and cardiorespiratory responses of young and adult athletes to a single session of high-intensity cycle exercise.

This study aimed to determine the effects of a single high-intensity interval training (HIIT) session on salivary cortisol (SC) levels, physiological responses, and performance in trained boys and men. Twenty-three boys (11.5 ± 0.8 years) and 25 men (29.7 ± 4.6 years) performed HIIT (4 consecutive Wingate Anaerobic Tests). SC in boys and men increased after HIIT from 5.55 ± 3.3 nmol/l to 15.13 ± 9.7 nmol/l (+173%) and from 7.07 ± 4.7 nmol/l to 19.19 ± 12.7 nmol/l (+171%), respectively (p < .01). Pretest SC as well as posttest changes were comparable in both groups (both p < .01). Peak blood lactate concentration was significantly lower in boys (12.6 ± 3.5 mmol/l) than in men (16.3 ± 3.1 mmol/l; p < .01). Throughout the HIIT, mean heart rates in boys were higher (p < .001) but relative peak oxygen uptake (ml·min-1·kg-1; p < .05) and performance were lower (p < .001) in boys than in men. HIIT in young athletes is associated with a higher activation of the hormonal stress axis than other types of exercise regimes as described in the literature. This study is the first to show a pronounced SC increase to HIIT in trained boys accompanied by elevated levels of blood lactate concentrations and heart rate suggesting a high cardio-respiratory, metabolic, and hormonal response to HIIT in 11-year-old boys.

Obtaining Energy Expenditure and Physical Activity from Acceleration Signals for Context-aware Evaluation of Cardiovascular Parameters

This work presents the design and development of an online daily-life activity measurement system. This system has been conceptualized to be used along with other vital parameter sensor-systems, e.g. blood-pressure and electrocardiogram (ECG), to provide the necessary context information for the evaluation of the health status of cardiovascular risk patients who are not hospitalized, but must be permanently monitored during their daily routines. The activity and energy expenditure are captured and estimated from accelerometers, which are placed on different points of the body. The activity, the ECG and the blood pressure are sent to a base station (smart phone or a PDA) and from there to a data base, to which the physicians have access. Thus it is possible to continuously analyze the vital data of a cardiovascular patient taking into consideration the activity or physical strain.

The kinetics of blood lactate in boys during and following a single and repeated all-out sprints of cycling are different than in men.

This study characterized the impact of high-intensity interval training on the kinetics of blood lactate and performance in trained boys and men. Twenty-one boys (11.4 ± 0.8 years) and 19 men (29.4 ± 5.0 years) performed a set of four 30-s sprints with 2-min of rest and a single 30-s sprint on 2 separate occasions (randomized order) with assessment of performance. Blood lactate was assayed after each sprint and during 30 min of recovery from both tests. The individual time-curves of blood lactate concentration were fitted to the biexponential function as follows: [Formula: see text], where the velocity parameters γ1 and γ2 reflect the capacity to release lactate from the previously active muscle into the blood and to subsequently eliminate lactate from the organism, respectively. In both tests, peak blood lactate concentration was significantly lower in the boys (four 30-s sprints: 12.2 ± 3.6 mmol·L(-1); single 30-s sprint: 8.7 ± 1.8 mmol·L(-1)) than men (four 30-s sprints: 16.1 ± 3.3 mmol·L(-1); single 30-s sprint: 11.5 ± 2.1; p < 0.001). The boys exhibited faster γ1 (1.4531 ± 0.65 min; p < 0.001) and γ2 (0.059 ± 0.023 min; p = 0.01) in the single 30-s sprint and faster γ2 (0.049 ± 0.016 min; p = 0.01) in the four 30-s sprints. The worsening of performance from the first to the last of the four 30-s sprints was less pronounced in boys (9.2% ± 13.9%) than men (19.2% ± 11.5%; p = 0.01). In the present study boys, when compared with men, exhibited lower Peak blood lactate concentration; less pronounced decline in performance during the sprints concomitantly with more rapid release and elimination during the single 30-s sprint; and faster elimination of lactate following the four 30-s sprints.

Kardiorespiratorische Fitness bei Erwachsenen in Deutschland

A high level of fitness is an indicator for a good health state. Therefore, cardiorespiratory fitness was examined in the cross-sectional German Health Interview Survey for Adults (DEGS1). Data from 3030 test-qualified adults between 18 and 64 years old were assessed by means of a standardized submaximal cycle ergometer test. Test-qualified participants were significantly younger, more often men, less often obese and showed a better health state than those who were not test-qualified. The calculated physical work capacity at 75 % of the age-predicted maximum heart rate (PWC75%) in watts per kg bodyweight was among men 1.52 and among women 1.15. PWC75% declines by 4.2 % per age decade for men and 4.8 % for women. A higher socioeconomic status (SES) is associated with better fitness among women. No significant association was observed between SES and fitness among men. These findings can be used to develop target-group specific health-promotion interventions in order to enhance cardiorespiratory fitness. It is planned to calculate updated PWC reference values based on the DEGS1 data. An English full-text version of this article is available at SpringerLink as supplemental.

[Cardiorespiratory fitness among adults in Germany: results of the German Health Interview and Examination Survey for Adults (DEGS1)].

A high level of fitness is an indicator for a good health state. Therefore, cardiorespiratory fitness was examined in the cross-sectional German Health Interview Survey for Adults (DEGS1). Data from 3030 test-qualified adults between 18 and 64 years old were assessed by means of a standardized submaximal cycle ergometer test. Test-qualified participants were significantly younger, more often men, less often obese and showed a better health state than those who were not test-qualified. The calculated physical work capacity at 75 % of the age-predicted maximum heart rate (PWC75%) in watts per kg bodyweight was among men 1.52 and among women 1.15. PWC75% declines by 4.2 % per age decade for men and 4.8 % for women. A higher socioeconomic status (SES) is associated with better fitness among women. No significant association was observed between SES and fitness among men. These findings can be used to develop target-group specific health-promotion interventions in order to enhance cardiorespiratory fitness. It is planned to calculate updated PWC reference values based on the DEGS1 data. An English full-text version of this article is available at SpringerLink as supplemental.

Using Support Vector Regression for Assessing Human Energy Expenditure Using a Triaxial Accelerometer and a Barometer

Physical inactivity is nowadays defined as the fourth leading risk factor for global mortality. These levels are rising worldwide with major aftereffects on the prevention of several diseases and the general health of the population. Energy expenditure (EE) is a very important parameter usually used as a dimension in physical activity assessment studies. However, the most accurate methods for the measurement of the EE are usually costly, obtrusive and most are limited by laboratory conditions. Recent technological advancements in the sensor technology along with the great progress made in algorithms have made accelerometers a powerful technique often used to assess everyday physical activity. This paper discusses the use of support vector regression (SVR) to predict EE by using a single measurement unit, equipped with a triaxial accelerometer and a barometer, attached to the subject´s hip.

[Daily ailments among healthy, middle-aged adults--situation report and explanatory approaches].

ZusammenfassungHintergrund: Die körperliche Leistungsfähigkeit nimmt auch bei Gesunden mit zunehmendem Alter ab.Methode: Mithilfe eines sportwissenschaftlichen Screenings wurde bei 222 gesunden Männern und Frauen mittleren Alters der Zusammenhang zwischen körperlicher Leistungsfähigkeit — Ausdauer, Kraft, Koordination, Beweglichkeit — und typischen Alltagsbeschwerden, die über einen Fragebogen erfasst wurden, untersucht. Die kardiopulmonale Leistungsfähigkeit wurde dabei mittels eines 2-km-Walking-Tests erhoben.Ergebnisse: Mit zunehmendem Alter und Bodymass-Index nahm die kardiopulmonale Leistungsfähigkeit signifikant ab. 44% der Männer und 29% der Frauen erreichten unterdurchschnittliche Werte bezogen auf die Normierungsstudie. Alltagsbeschwerden wie „Schwierigkeiten beim Treppensteigen“ oder „Schnell außer Atem kommen“ zeigten einen deutlichen Zusammenhang mit der aus dem Ausdauertest geschätzten kardiopulmonalen Leistungsfähigkeit; Kraft und Beweglichkeit hatten hingegen einen geringeren Einfluss. Der Zusammenhang zwischen nachlassender Leistungsfähigkeit des Herz-Kreislauf-Systems und Alltagsbeschwerden war den Probanden dabei nicht bewusst.Schlussfolgerung: Ein einfaches Screening wäre ein guter Einstieg für, um sportlich wenig engagierte Menschen mittleren Alters dazu motivieren, ein adäquates gesundheitsorientiertes Bewegungsangebot weiterzuführen.HeadingBackground: Physical performance steadily declines with increasing age even among healthy adults.Methods: A sport scientific screening-battery was used to determine the relationship between physical performance — that is endurance, strength, coordination, flexibility — and typical daily ailments as measured by a questionnaire among 222 healthy, middle-aged women and men. Cardiopulmonary performance was estimated by a 2-km walking test.Results: Cardiopulmonary performance declined significantly as a result of increasing age and increasing body-mass index. 44% of men and 29% of women reached substandard values when compared to norm tables. Daily ailments such as „Problems while climbing stairs“ or „Breathing difficulty“ showed a strong correlation to the estimated cardiopulmonary performance. In contrast, they were less influenced by strength or flexibility. The subjects were oblivious of the relationship between the decreased performance of the cardiovascular system and daily ailments.Conclusion: Performing a simple screening-battery may be a good chance to promote the participation of middle-aged and non-athletic people in an adequate and health oriented sports program.

Cardiorespiratory fitness among adults in Germany

A high level of fitness is an indicator for a good health state. Therefore, cardiorespiratory fitness was examined in the cross-sectional German Health Interview Survey for Adults (DEGS1). Data from 3030 test-qualified adults between 18 and 64 years old were assessed by means of a standardized submaximal cycle ergometer test. Test-qualified participants were significantly younger, more often men, less often obese and showed a better health state than those who were not test-qualified. The calculated physical work capacity at 75 % of the age-predicted maximum heart rate (PWC75%) in watts per kg bodyweight was among men 1.52 and among women 1.15. PWC75% declines by 4.2 % per age decade for men and 4.8 % for women. A higher socioeconomic status (SES) is associated with better fitness among women. No significant association was observed between SES and fitness among men. These findings can be used to develop target-group specific health-promotion interventions in order to enhance cardiorespiratory fitness. It is planned to calculate updated PWC reference values based on the DEGS1 data. An English full-text version of this article is available at SpringerLink as supplemental.