Effects of aerobic exercise training on heart rate variability during wakefulness and sleep and cardiorespiratory responses of young and middle-aged healthy men

The purpose of the present study was to evaluate the effects of aerobic physical training (APT) on heart rate variability (HRV) and cardiorespiratory responses at peak condition and ventilatory anaerobic threshold. Ten young (Y: median = 21 years) and seven middle-aged (MA = 53 years) healthy sedentary men were studied. Dynamic exercise tests were performed on a cycloergometer using a continuous ramp protocol (12 to 20 W/min) until exhaustion. A dynamic 24-h electrocardiogram was analyzed by time (TD) (standard deviation of mean R-R intervals) and frequency domain (FD) methods. The power spectral components were expressed as absolute (a) and normalized units (nu) at low (LF) and high (HF) frequencies and as the LF/HF ratio. Control (C) condition: HRV in TD (Y: 108, MA: 96 ms; P<0.05) and FD - LFa, HFa - was significantly higher in young (1030; 2589 ms²/Hz) than in middle-aged men (357; 342 ms²/Hz) only during sleep (P<0.05); post-training effects: resting bradycardia (P<0.05) in the awake condition in both groups; VO2 increased for both groups at anaerobic threshold (P<0.05), and at peak condition only in young men; HRV in TD and FD (a and nu) was not significantly changed by training in either groups. The vagal predominance during sleep is reduced with aging. The resting bradycardia induced by short-term APT in both age groups suggests that this adaptation is much more related to intrinsic alterations in sinus node than in efferent vagal-sympathetic modulation. Furthermore, the greater alterations in VO2 than in HRV may be related to short-term APT.

Effects of losartan combined with exercise training in spontaneously hypertensive rats

We investigate whether combined treatment with losartan, an angiotensin II receptor blocker, and exercise training (ET) in spontaneously hypertensive rats (SHR) would have an additive effect in reducing hypertension and improving baroreflex sensitivity when compared with losartan alone. Male SHR (8 weeks old) were assigned to 3 groups: sedentary placebo (SP, N = 16), sedentary under losartan treatment (SL, N = 11; 10 mg kg-1 day-1, by gavage), and ET under losartan treatment (TL, N = 10). ET was performed on a treadmill 5 days/week for 60 min at 50% of peak VO2, for 18 weeks. Blood pressure (BP) was measured with a catheter inserted into the carotid artery, and cardiac output with a microprobe placed around the ascending aorta. The baroreflex control of heart rate was assessed by administering increasing doses of phenylephrine and sodium nitroprusside (iv). Losartan significantly reduced mean BP (178 ± 16 vs 132 ± 12 mmHg) and left ventricular hypertrophy (2.9 ± 0.4 vs 2.5 ± 0.2 mg/g), and significantly increased baroreflex bradycardia and tachycardia sensitivity (1.0 ± 0.3 vs 1.7 ± 0.5 and 2.0 ± 0.7 vs 3.2 ± 1.7 bpm/mmHg, respectively) in SL compared with SP. However, losartan combined with ET had no additional effect on BP, baroreflex sensitivity or left ventricular hypertrophy when compared with losartan alone. In conclusion, losartan attenuates hypertension and improves baroreflex sensitivity in SHR. However, ET has no synergistic effect on BP in established hypertension when combined with losartan, at least at the dosage used in this investigation.

Duration-controlled swimming exercise training induces cardiac hypertrophy in mice

Exercise training associated with robust conditioning can be useful for the study of molecular mechanisms underlying exercise-induced cardiac hypertrophy. A swimming apparatus is described to control training regimens in terms of duration, load, and frequency of exercise. Mice were submitted to 60- vs 90-min session/day, once vs twice a day, with 2 or 4% of the weight of the mouse or no workload attached to the tail, for 4 vs 6 weeks of exercise training. Blood pressure was unchanged in all groups while resting heart rate decreased in the trained groups (8-18%). Skeletal muscle citrate synthase activity, measured spectrophotometrically, increased (45-58%) only as a result of duration and frequency-controlled exercise training, indicating that endurance conditioning was obtained. In groups which received duration and endurance conditioning, cardiac weight (14-25%) and myocyte dimension (13-20%) increased. The best conditioning protocol to promote physiological hypertrophy, our primary goal in the present study, was 90 min, twice a day, 5 days a week for 4 weeks with no overload attached to the body. Thus, duration- and frequency-controlled exercise training in mice induces a significant conditioning response qualitatively similar to that observed in humans.

Spatial modeling techniques for mapping and characterization of acid sulfate soils

Acid sulfate (a.s.) soils constitute a major environmental issue. Severe ecological damage results from the considerable amounts of acidity and metals leached by these soils in the recipient watercourses. As even small hot spots may affect large areas of coastal waters, mapping represents a fundamental step in the management and mitigation of a.s. soil environmental risks (i.e. to target strategic areas). Traditional mapping in the field is time-consuming and therefore expensive. Additional more cost-effective techniques have, thus, to be developed in order to narrow down and define in detail the areas of interest. The primary aim of this thesis was to assess different spatial modeling techniques for a.s. soil mapping, and the characterization of soil properties relevant for a.s. soil environmental risk management, using all available data: soil and water samples, as well as datalayers (e.g. geological and geophysical). Different spatial modeling techniques were applied at catchment or regional scale. Two artificial neural networks were assessed on the Sirppujoki River catchment (c. 440 km2) located in southwestern Finland, while fuzzy logic was assessed on several areas along the Finnish coast. Quaternary geology, aerogeophysics and slope data (derived from a digital elevation model) were utilized as evidential datalayers. The methods also required the use of point datasets (i.e. soil profiles corresponding to known a.s. or non-a.s. soil occurrences) for training and/or validation within the modeling processes. Applying these methods, various maps were generated: probability maps for a.s. soil occurrence, as well as predictive maps for different soil properties (sulfur content, organic matter content and critical sulfide depth). The two assessed artificial neural networks (ANNs) demonstrated good classification abilities for a.s. soil probability mapping at catchment scale. Slightly better results were achieved using a Radial Basis Function (RBF) -based ANN than a Radial Basis Functional Link Net (RBFLN) method, narrowing down more accurately the most probable areas for a.s. soil occurrence and defining more properly the least probable areas. The RBF-based ANN also demonstrated promising results for the characterization of different soil properties in the most probable a.s. soil areas at catchment scale. Since a.s. soil areas constitute highly productive lands for agricultural purpose, the combination of a probability map with more specific soil property predictive maps offers a valuable toolset to more precisely target strategic areas for subsequent environmental risk management. Notably, the use of laser scanning (i.e. Light Detection And Ranging, LiDAR) data enabled a more precise definition of a.s. soil probability areas, as well as the soil property modeling classes for sulfur content and the critical sulfide depth. Given suitable training/validation points, ANNs can be trained to yield a more precise modeling of the occurrence of a.s. soils and their properties. By contrast, fuzzy logic represents a simple, fast and objective alternative to carry out preliminary surveys, at catchment or regional scale, in areas offering a limited amount of data. This method enables delimiting and prioritizing the most probable areas for a.s soil occurrence, which can be particularly useful in the field. Being easily transferable from area to area, fuzzy logic modeling can be carried out at regional scale. Mapping at this scale would be extremely time-consuming through manual assessment. The use of spatial modeling techniques enables the creation of valid and comparable maps, which represents an important development within the a.s. soil mapping process. The a.s. soil mapping was also assessed using water chemistry data for 24 different catchments along the Finnish coast (in all, covering c. 21,300 km2) which were mapped with different methods (i.e. conventional mapping, fuzzy logic and an artificial neural network). Two a.s. soil related indicators measured in the river water (sulfate content and sulfate/chloride ratio) were compared to the extent of the most probable areas for a.s. soils in the surveyed catchments. High sulfate contents and sulfate/chloride ratios measured in most of the rivers demonstrated the presence of a.s. soils in the corresponding catchments. The calculated extent of the most probable a.s. soil areas is supported by independent data on water chemistry, suggesting that the a.s. soil probability maps created with different methods are reliable and comparable.

Swimming training increases cardiac vagal activity and induces cardiac hypertrophy in rats

The effect of swimming training (ST) on vagal and sympathetic cardiac effects was investigated in sedentary (S, N = 12) and trained (T, N = 12) male Wistar rats (200-220 g). ST consisted of 60-min swimming sessions 5 days/week for 8 weeks, with a 5% body weight load attached to the tail. The effect of the autonomic nervous system in generating training-induced resting bradycardia (RB) was examined indirectly after cardiac muscarinic and adrenergic receptor blockade. Cardiac hypertrophy was evaluated by cardiac weight and myocyte morphometry. Plasma catecholamine concentrations and citrate synthase activity in soleus muscle were also determined in both groups. Resting heart rate was significantly reduced in T rats (355 ± 16 vs 330 ± 20 bpm). RB was associated with a significantly increased cardiac vagal effect in T rats (103 ± 25 vs 158 ± 40 bpm), since the sympathetic cardiac effect and intrinsic heart rate were similar for the two groups. Likewise, no significant difference was observed for plasma catecholamine concentrations between S and T rats. In T rats, left ventricle weight (13%) and myocyte dimension (21%) were significantly increased, suggesting cardiac hypertrophy. Skeletal muscle citrate synthase activity was significantly increased by 52% in T rats, indicating endurance conditioning. These data suggest that RB induced by ST is mainly mediated parasympathetically and differs from other training modes, like running, that seems to mainly decrease intrinsic heart rate in rats. The increased cardiac vagal activity associated with ST is of clinical relevance, since both are related to increased life expectancy and prevention of cardiac events.

Response of the arterial blood pressure of quadriplegic patients to treadmill gait training

Blood pressure pattern was analyzed in 12 complete quadriplegics with chronic lesions after three months of treadmill gait training. Before training, blood pressure values were obtained at rest, during treadmill walking and during the recovery phase. Gait training was performed for 20 min twice a week for three months. Treadmill gait was achieved using neuromuscular electrical stimulation, assisted by partial body weight relief (30-50%). After training, blood pressure was evaluated at rest, during gait and during recovery phase. Before and after training, mean systolic blood pressures and heart rates increased significantly during gait compared to rest (94.16 ± 5.15 to 105 ± 5.22 mmHg and 74.27 ± 10.09 to 106.23 ± 17.31 bpm, respectively), and blood pressure decreased significantly in the recovery phase (86.66 ± 9.84 and 57.5 ± 8.66 mmHg, respectively). After three months of training, systolic blood pressure became higher at rest (94.16 ± 5.15 mmHg before training and 100 ± 8.52 mmHg after training; P < 0.05) and during gait exercise (105 ± 5.22 mmHg before and 110 ± 7.38 mmHg after training; P < 0.05) when compared to the initial values, with no changes in heart rate. No changes occurred in blood pressure during the recovery phase, with the lower values being maintained. A drop in systolic pressure from 105 ± 5.22 to 86.66 ± 9.84 mmHg before training and from 110 ± 7.38 to 90 ± 7.38 mmHg after training was noticed immediately after exercise, thus resulting in hypotensive symptoms when chronic quadriplegics reach the sitting position from the upright position.

Effects of diet and exercise training on neurovascular control during mental stress in obese women

Since neurovascular control is altered in obese subjects, we hypothesized that weight loss by diet (D) or diet plus exercise training (D + ET) would improve neurovascular control during mental stress in obese women. In a study with a dietary reduction of 600 kcal/day with or without exercise training for 4 months, 53 obese women were subdivided in D (N = 22, 33 ± 1 years, BMI 34 ± 1 kg/m²), D + ET (N = 22, 33 ± 1 years, BMI 33 ± 1 kg/m²), and nonadherent (NA, N = 9, 35 ± 2 years, BMI 33 ± 1 kg/m²) groups. Muscle sympathetic nerve activity (MSNA) was measured by microneurography and forearm blood flow by venous occlusion plethysmography. Mental stress was elicited by a 3-min Stroop color word test. Weight loss was similar between D and D + ET groups (87 ± 2 vs 79 ± 2 and 85 ± 2 vs 76 ± 2 kg, respectively, P < 0.05) with a significant reduction in MSNA during mental stress (58 ± 2 vs 50 ± 2, P = 0.0001, and 59 ± 3 vs 50 ± 2 bursts/100 beats, P = 0.0001, respectively), although the magnitude of the response was unchanged. Forearm vascular conductance during mental stress was significantly increased only in D + ET (2.74 ± 0.22 vs 3.52 ± 0.19 units, P = 0.02). Weight loss reduces MSNA during mental stress in obese women. The increase in forearm vascular conductance after weight loss provides convincing evidence for D + ET interventions as a nonpharmacologic therapy of human obesity.

Comparison of morning and afternoon exercise training for asthmatic children

Fitness improvement was used to compare morning with afternoon exercise periods for asthmatic children. Children with persistent moderate asthma (according to GINA criteria), 8 to 11 years old, were divided into 3 groups: morning training group (N = 23), afternoon training group (N = 23), and non-training group (N = 23). The program was based on twice a week 90-min sessions for 4 months. We measured the 9-min running distance, resting heart rate and abdominal muscle strength (sit-up number) before and after the training. All children took budesonide, 400 µg/day, and an on demand inhaled ß-agonist. The distance covered in 9 min increased (mean ± SEM) from 1344 ± 30 m by 248 ± 30 m for the morning group, from 1327 ± 30 m by 162 ± 20 m for the afternoon group, and from 1310 ± 20 m by 2 ± 20 m for the control group (P < 0.05 for the comparison of morning and afternoon groups with the control group by ANOVA and P > 0.05 for morning with afternoon comparison). The reduction of resting heart rate from 83 ± 1, 85 ± 2 and 86 ± 1 bpm was 5.1 ± 0.8 bpm in the morning group, 4.4 ± 0.8 bpm in the afternoon group, and -0.2 ± 0.7 bpm in the control group (P > 0.05 for morning with afternoon comparison and P < 0.05 versus control). The number of sit-ups in the morning, afternoon and control groups increased from 22.0 ± 1.7, 24.3 ± 1.4 and 23 ± 1.1 sit-ups by 9.8 ± 0.9, 7.7 ± 1.4, and 1.9 ± 0.7 sit-ups, respectively (P > 0.05 for morning with afternoon comparison and P < 0.05 versus control). No statistically significant differences were detected between the morning and afternoon groups in terms of physical training of asthmatic children.

L-carnitine as an ergogenic aid for patients with chronic obstructive pulmonary disease submitted to whole-body and respiratory muscle training programs

The effects of adding L-carnitine to a whole-body and respiratory training program were determined in moderate-to-severe chronic obstructive pulmonary disease (COPD) patients. Sixteen COPD patients (66 ± 7 years) were randomly assigned to L-carnitine (CG) or placebo group (PG) that received either L-carnitine or saline solution (2 g/day, orally) for 6 weeks (forced expiratory volume on first second was 38 ± 16 and 36 ± 12%, respectively). Both groups participated in three weekly 30-min treadmill and threshold inspiratory muscle training sessions, with 3 sets of 10 loaded inspirations (40%) at maximal inspiratory pressure. Nutritional status, exercise tolerance on a treadmill and six-minute walking test, blood lactate, heart rate, blood pressure, and respiratory muscle strength were determined as baseline and on day 42. Maximal capacity in the incremental exercise test was significantly improved in both groups (P < 0.05). Blood lactate, blood pressure, oxygen saturation, and heart rate at identical exercise levels were lower in CG after training (P < 0.05). Inspiratory muscle strength and walking test tolerance were significantly improved in both groups, but the gains of CG were significantly higher than those of PG (40 ± 14 vs 14 ± 5 cmH2O, and 87 ± 30 vs 34 ± 29 m, respectively; P < 0.05). Blood lactate concentration was significantly lower in CG than in PG (1.6 ± 0.7 vs 2.3 ± 0.7 mM, P < 0.05). The present data suggest that carnitine can improve exercise tolerance and inspiratory muscle strength in COPD patients, as well as reduce lactate production.

Early remodeling of rat cardiac muscle induced by swimming training

The aim of the present investigation was to study the effect of acute swimming training with an anaerobic component on matrix metallopeptidase (MMP) activity and myosin heavy chain gene expression in the rat myocardium. Animals (male Wistar rats, weighing approximately 180 g) were trained for 6 h/day in 3 sessions of 2 h each for 1 to 5 consecutive days (N = 5 rats per group). Rats swam in basins 47 cm in diameter and 60 cm deep filled with water at 33 to 35ºC. After the training period a significant increase (P < 0.05) was observed in the heart weight normalized to body weight by about 22 and 35% in the groups that trained for 96 and 120 h, respectively. Blood lactate levels were significantly increased (P < 0.05) in all groups after all training sessions, confirming an anaerobic component. However, lactate levels decreased (P < 0.05) with days of training, suggesting that the animals became adapted to this protocol. Myosin heavy chain-ß gene expression, analyzed by real time PCR and normalized with GAPDH gene expression, showed a significant two-fold increase (P < 0.01) after 5 days of training. Zymography analysis of myocardium extracts indicated a single ~60-kDa activity band that was significantly increased (P < 0.05) after 72, 96, and 120 h, indicating an increased expression of MMP-2 and suggesting precocious remodeling. Furthermore, the presence of MMP-2 was confirmed by Western blot analysis, but not the presence of MMP-1 and MMP-3. Taken together, our results indicate that in these training conditions, the rat heart undergoes early biochemical and functional changes required for the adaptation to the new physiological condition by tissue remodeling.

Differential evolution based classification with pool of distances and aggregation operators

The objective of this thesis is to develop and generalize further the differential evolution based data classification method. For many years, evolutionary algorithms have been successfully applied to many classification tasks. Evolution algorithms are population based, stochastic search algorithms that mimic natural selection and genetics. Differential evolution is an evolutionary algorithm that has gained popularity because of its simplicity and good observed performance. In this thesis a differential evolution classifier with pool of distances is proposed, demonstrated and initially evaluated. The differential evolution classifier is a nearest prototype vector based classifier that applies a global optimization algorithm, differential evolution, to determine the optimal values for all free parameters of the classifier model during the training phase of the classifier. The differential evolution classifier applies the individually optimized distance measure for each new data set to be classified is generalized to cover a pool of distances. Instead of optimizing a single distance measure for the given data set, the selection of the optimal distance measure from a predefined pool of alternative measures is attempted systematically and automatically. Furthermore, instead of only selecting the optimal distance measure from a set of alternatives, an attempt is made to optimize the values of the possible control parameters related with the selected distance measure. Specifically, a pool of alternative distance measures is first created and then the differential evolution algorithm is applied to select the optimal distance measure that yields the highest classification accuracy with the current data. After determining the optimal distance measures for the given data set together with their optimal parameters, all determined distance measures are aggregated to form a single total distance measure. The total distance measure is applied to the final classification decisions. The actual classification process is still based on the nearest prototype vector principle; a sample belongs to the class represented by the nearest prototype vector when measured with the optimized total distance measure. During the training process the differential evolution algorithm determines the optimal class vectors, selects optimal distance metrics, and determines the optimal values for the free parameters of each selected distance measure. The results obtained with the above method confirm that the choice of distance measure is one of the most crucial factors for obtaining higher classification accuracy. The results also demonstrate that it is possible to build a classifier that is able to select the optimal distance measure for the given data set automatically and systematically. After finding optimal distance measures together with optimal parameters from the particular distance measure results are then aggregated to form a total distance, which will be used to form the deviation between the class vectors and samples and thus classify the samples. This thesis also discusses two types of aggregation operators, namely, ordered weighted averaging (OWA) based multi-distances and generalized ordered weighted averaging (GOWA). These aggregation operators were applied in this work to the aggregation of the normalized distance values. The results demonstrate that a proper combination of aggregation operator and weight generation scheme play an important role in obtaining good classification accuracy. The main outcomes of the work are the six new generalized versions of previous method called differential evolution classifier. All these DE classifier demonstrated good results in the classification tasks.

Novel word learning ability in chronic post-stroke aphasia : variability and modality effects

Novel word learning has been rarely studied in people with aphasia (PWA), although it can provide a relatively pure measure of their learning potential, and thereby contribute to the development of effective aphasia treatment methods. The main aim of the present thesis was to explore the capacity of PWA for associative learning of word–referent pairings and cognitive-linguistic factors related to it. More specifically, the thesis examined learning and long-term maintenance of the learned pairings, the role of lexical-semantic abilities in learning as well as acquisition of phonological versus semantic information in associative novel word learning. Furthermore, the effect of modality on associative novel word learning and the neural underpinnings of successful learning were explored. The learning experiments utilized the Ancient Farming Equipment (AFE) paradigm that employs drawings of unfamiliar referents and their unfamiliar names. Case studies of Finnishand English-speaking people with chronic aphasia (n = 6) were conducted in the investigation. The learning results of PWA were compared to those of healthy control participants, and active production of the novel words and their semantic definitions was used as learning outcome measures. PWA learned novel word–novel referent pairings, but the variation between individuals was very wide, from more modest outcomes (Studies I–II) up to levels on a par with healthy individuals (Studies III–IV). In incidental learning of semantic definitions, none of the PWA reached the performance level of the healthy control participants. Some PWA maintained part of the learning outcomes up to months post-training, and one individual showed full maintenance of the novel words at six months post-training (Study IV). Intact lexical-semantic processing skills promoted learning in PWA (Studies I–II) but poor phonological short-term memory capacities did not rule out novel word learning. In two PWA with successful learning and long-term maintenance of novel word–novel referent pairings, learning relied on orthographic input while auditory input led to significantly inferior learning outcomes (Studies III–IV). In one of these individuals, this previously undetected modalityspecific learning ability was successfully translated into training with familiar but inaccessible everyday words (Study IV). Functional magnetic resonance imaging revealed that this individual had a disconnected dorsal speech processing pathway in the left hemisphere, but a right-hemispheric neural network mediated successful novel word learning via reading. Finally, the results of Study III suggested that the cognitive-linguistic profile may not always predict the optimal learning channel for an individual with aphasia. Small-scale learning probes seem therefore useful in revealing functional learning channels in post-stroke aphasia.