330 research outputs found

    Iterative complex network approach for chemical gas sensor array characterisation

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    Gas sensor arrays, also known as e-noses, are used in several heterogeneous fields, ranging from environmental monitoring to food quality control. Often, these measurement systems operate within dynamic environments and are subject to conditions which may dramatically vary over time. Furthermore, the response of an e-nose is influenced by several parameters, whose interactions may be complex and highly non-linear. Therefore, in this study, the authors propose a complex network approach to model the overall interaction pattern of e-noses. They show that this approach can significantly improve the understanding of the overall behaviour of e-noses, and can be used as a basis to optimise the design of these measurement systems

    Analysis of anaerobic power in club level young rowers

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    Aim: To date, assessment of the anaerobic components to determine performance in rowers is not part of standard evaluation or monitoring set for training. The aim of this study was to evaluate the relation between anaerobic power output and ergometer rowing performance over 2000 meters, in a group of 14 -17 years old rowers (n = 11). Methods: Each subject performed, in three separate days, two “all-out” tests, over 20 and 60 seconds, and a 2000 meters trial, using a Concept II rowing ergometer. Mean power values over 20 sec (W20) and 60 sec (W60) were measured and compared with the time to perform the 2000 m trial (t2000). Results: Statistical analysis showed high and significant correlation between 2000 meters performance (6.90 ± 0.1 min) and anaerobic power over 20 sec (479.5 ± 93.90 watts; r = 0.941, P = 0.00002) and 60 sec (435.5 ± 64.60 watts; r = 0.964, P = 0.000002). Conclusions: The data of our study confirm that parameters of anaerobic power strongly affect the performance and that the determination of these variables by testing on rowing ergometer can be an useful tool for planning and monitoring of training in young rowers

    Effetti cardiorespiratori degli sprint ripetuti in giovani calciatori

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    Scopo: Nel calcio la performance dipende da attività caratterizzate da sforzi di breve durata, talora ad alta intensità, con ridotti tempi di recupero. Questo tipo di sforzo può avere maggiore potenzialità aritmogena rispetto a sforzi, anche massimali, iniziati e terminati in modo graduale. Gli sprint ripetuti permettono di valutare la performance e lo stato di allenamento in giovani calciatori. Scopo del nostro lavoro è stato quello di valutare gli effetti degli sprint ripetuti sul sistema cardiorespiratorio in giovani calciatori delle rappresentative regionali siciliane della FIGC. Metodi: Sono stati esaminati 12 calciatori, di età media di 15±1 anni. Per valutare lo stato di fitness cardiorespiratoria sono stati determinati, al test da sforzo incrementale massimale al treadmill (SI), il VO2max in ml.Kg-1.min-1 (VO2maxSI) e la FCmax in bpm (FCmaxSI). Per valutare gli effetti cardiorespiratori degli sprint ripetuti, gli atleti hanno eseguito un test da sforzo al cicloergometro a freno meccanico (SR) che prevedeva 10 sprint massimali “all-out” di 6 sec, intervallati da 30 sec di recupero passivo. Nella serie dei 10 sprint, sono stati determinati il valore più elevato di VO2 in ml.Kg-1.min-1 (VO2maxSR) e di FC in bpm (FCmaxSR). Risultati: Il valore medio di VO2maxSI (56,22±3,93 ml.Kg-1.min-1) indica che i soggetti esaminati hanno un buon livello di potenza aerobica, raggiunta ad una FCmaxSI di 190±8 bpm. I dati di VO2maxSR rilevati al test degli sprint ripetuti evidenziano un valore medio di 42,67±5,57 ml.Kg-1.min-1 (70% del VO2maxSI), raggiunto ad una FCmaxSR di 175±11 bpm (92% della FCmaxSI). Conclusioni: I dati del nostro studio indicano che nei soggetti esaminati gli sprint ripetuti determinano incrementi della frequenza cardiaca rapidi, elevati e persistenti nella fase di recupero. Questo dato deve essere preso in considerazione non solo per la valutazione della performance ma anche nella formulazione dell’idoneità a praticare la disciplina sportiva del calcio

    Relationship Between Heart Rate Recovery After Exercise and Maximal Oxygen Uptake in Sedentary Patients with Type 2 Diabetes

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    AIMS: Heart rate recovery after exercise (HRR) is an estimate of autonomic modulation of the heart, and has been shown to be inversely associated with type 2 diabetes. Type 2 diabetes is associated with decreased maximal oxygen consumption (VO2max). Aim of our study was to assess the relationship between HRR and VO2max in sedentary patients with type 2 diabetes. METHODS: Maximal exercise testing to determine VO2max (ml ∙ Kg-1 ∙ min-1) was performed in 16 sedentary patients with type 2 diabetes (DP) and in 16 age-matched sedentary healthy controls (HS). HRR (bpm) 2 min after cessation of the exercise was recorded. Simple linear regression was used to assess the relations between HRR and VO2max. RESULTS: VO2max and HRR were significantly lower in DP compared to HS (P = 0.002 and P = 0.008 respectively). A correlation between HRR and VO2max has been found, stronger in DP (r = 0.672, P = 0.004) than HS (r = 0.620, P = 0.01). CONCLUSIONS: Our study suggests that regular physical activity aimed to improve the levels of VO2max in subjects with diabetes may improve the HRR and reduce the risk of cardiovascular events

    Relationship between heart rate variability and repeated sprint exercise in young soccer players

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    Aim: The sport of soccer is characterized by neuromuscular performance resulting in short bursts interspersed by brief recovery periods over an extended period of time. Several studies suggest that the cardiac autonomic nervous system (ANS) assessed by heart rate variability (HRV) may provide useful information regarding the functional adaptations to training stimulus. Although HRV has often been associated with aerobic power and cardiovascular fitness, the influence of sympathovagal balance on neuromuscular performance in young athletes is not well assessed. The aim of this study was to assess the influence of the autonomic system on the performance of repeated sprints, involving predominantly muscular power and anaerobic metabolism, in young soccer players. Method: Twelve young soccer players, selected for the Sicilian Regional Representative of the Italian Football Federation, mean age 15 years, were recruited. Resting HRV was measured and indices of power spectral analysis (ratio LF/HF) were calculated to evaluate the sympathovagal balance. To assess the state of physical fitness of subjects, VO2max was determined by maximal graded treadmill test. Finally, the athletes performed 10 maximal all-out 6-sec cycling sprints (RS), interspersed with 30-sec of passive recovery, to measure the peak power (PP) represented by the highest value recorded during a single sprint, and the average of the values of maximum power (AP) recorded during all sprints. Results: On the basis of their VO2max (56.22 ± 3.93 ml/Kg/min), all subjects showed good levels of physical fitness. HRV index (LF/HF = 1.31 ± 0.74) showed an inverse correlation with PP (14.05 ± 0.89 W/Kg; r = -0.709, P = 0.01), and with AP (12.82 ± 0.88 W/Kg; r = -0.606, P = 0.04). Conclusion: Our study shows that a low ratio LF/HF, which reflects a parasympathetic predominance in the ANS balance, is associated with a better anaerobic contribution to performance resulting in higher values of PP and AP during brief repeated maximal cycling sprints. The assessment of resting HRV before exercise may be useful for performance monitoring of young soccer players

    Predicting the 2000-m rowing ergometer performance from anthropometric, maximal oxygen uptake and 60-s mean power variables in national level young rowers

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    Many studies reported various relationships between 2000-m rowing performance and anthropometric as well as metabolic variables, however, little is known about 60-s mean power in elite youth athletes. The aim of this study was to develop different regression models to predict 2000-m rowing indoor performance time (t2000)using anthropometric variables, maximal oxygen uptake (VO2max) and mean power established during a 60-s all-out test (W60) in national elite youth rowers. Fifteen youth male Italian rowers (age: 15.7 \ub1 2.0 years; body height: 176.0 \ub1 8.0 cm; body mass: 71.2 \ub1 10.0 kg) performed an incremental maximal test, a 60-s all-out test and a 2000-m race simulation using a Concept2 rowing ergometer to assess VO2max, W60and t2000, respectively. The relationships of all variables with t2000 were investigated through Pearson\u2019s correlation. Multiple regression analyses were used to verify the best prediction model of 2000-m indoor rowing performance. The reliability of these models was expressed by R2 and the standard error of estimate. The results showed that t2000 was significantly correlated with all the examined variables, except for VO2max/body mass and age, and exhibited the significantly highest relationship with W60 (r = -0.943). The combination of anthropometric, VO2max and W60 variables was found to be the most reliable equation to predict t2000 (R2 = 0.94, SEE = 6.4). W60 measure should be considered when monitoring the rower\u2019s capability to perform high-intensity phases, important during the race\u2019s fast start and end. Not requiring expensive equipment and long duration, a 60-s all-out test could be considered a valuable tool for predicting 2000-m performance of elite youth rowers

    Advanced Video-Based Processing for Low-Cost Damage Assessment of Buildings under Seismic Loading in Shaking Table Tests

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    This paper explores the potential of a low-cost, advanced video-based technique for the assessment of structural damage to buildings caused by seismic loading. A low-cost, high-speed video camera was utilized for the motion magnification processing of footage of a two-story reinforcedconcrete frame building subjected to shaking table tests. The damage after seismic loading was estimated by analyzing the dynamic behavior (i.e., modal parameters) and the structural deformations of the building in magnified videos. The results using the motion magnification procedure were compared for validation of the method of the damage assessment obtained through analyses of conventional accelerometric sensors and high-precision optical markers tracked using a passive 3D motion capture system. In addition, 3D laser scanning to obtain an accurate survey of the building geometry before and after the seismic tests was carried out. In particular, accelerometric recordings were also processed and analyzed using several stationary and nonstationary signal processing techniques with the aim of analyzing the linear behavior of the undamaged structure and the nonlinear structural behavior during damaging shaking table tests. The proposed procedure based on the analysis of magnified videos provided an accurate estimate of the main modal frequency and the damage location through the analysis of the modal shapes, which were confirmed using advanced analyses of the accelerometric data. Consequently, the main novelty of the study was the highlighting of a simple procedure with high potential for the extraction and analysis of modal parameters, with a special focus on the analysis of the modal shape’s curvature, which provides accurate information on the location of the damage in a structure, while using a noncontact and low-cost method

    Redox and autonomic responses to acute exercise-post recovery following Opuntia ficus-indica juice intake in physically active women

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    Background: The aim of this study was to investigate if the supplementation with Opuntia ficus-indica (OFI) juice may affect plasma redox balance and heart rate variability (HRV) parameters following a maximal effort test, in young physically active women. Methods: A randomized, double blind, placebo controlled and crossover study comprising eight women (23.25 ± 2.95 years, 54.13 ± 9.05 kg, 157.75 ± 0.66 cm and BMI of 21.69 ± 0.66 kg/m2) was carried out. A juice containing OFI diluted in water and a Placebo solution were supplied (170 ml; OFI = 50 ml of OFI juice + 120 ml of water; Placebo = 170 ml beverage without Vitamin C and indicaxanthin). Participants consumed the OFI juice or Placebo beverage every day for 3 days, before performing a maximal cycle ergometer test, and for 2 consecutive days after the test. Plasma hydroperoxides and total antioxidant capacity (PAT), Skin Carotenoid Score (SCS) and HRV variables (LF, HF, LF/HF and rMSSD) were recorded at different time points. Results: The OFI group showed significantly lower levels of hydroperoxides compared to the Placebo group in pretest, post-test and 48-h post-test. PAT values of the OFI group significantly increased compared to those of the Placebo group in pre-test and 48-h post-test. SCS did not differ between groups. LF was significantly lower in the OFI group 24-h after the end of the test, whereas rMSSD was significantly higher in the OFI group 48-h post-test. Conclusion: OFI supplementation decreased the oxidative stress induced by intense exercise and improved autonomic balance in physically active women

    Relationship between wingate cycle test and 2000m rowing ergometer performance in youth athletes

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    During 2000m indoor rowing performances, the estimated aerobic and anaerobic contribution are 65-75% and 25-35%, respectively2. In considering that anaerobic power could be an important predictor of performance1, the aim of this study was to analyse the relationship between the power outputs during a Wingate anaerobic test (WAnT) on a cycling ergometer and a 2000m rowing ergometer performance in young rowers. In two separate days, 11 young (14.9±1.1yrs) male rowers performed a 2000m indoor rowing ergometer performance and a 30s WAnT on a cycling ergometer. WAnT peak power (PP) and mean power (MP), and 2000m time indoor rowing performance (t2000) were collected. Moreover, PP and MP were normalized with respect to body mass. Pearson correlation coefficients (r) were used to determine the association between t2000 and absolute and normalized PP and MP values. Absolute PP and MP were 888.1±133.2W and 548.5±74.4W, respectively. The relative picture for normalized values was 13.4±1.5 W·kg-1 and 8.2±0.6 W·kg-1. High associations emerged between t2000 (431.5±19.5s) and absolute PP (r=-0.900, P=0.05) values, whereas no significant relationship was observed for normalized PP (r=-0.585, P=0.058) and AP (r=-0.561, P=0.072) values. These findings indicate that PP and MP could be considered significant predictors of 2000m rowing ergometer performances, substantiating also the relevance of the anaerobic energy pathways to the 2,000m rowing performance
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