Smart System with Artificial Intelligence for Sensory Gloves.

This paper presents a new sensory system based on advanced algorithms and machine learning techniques that provides sensory gloves with the ability to ensure real-time connection of all connectors in the cabling of a cockpit module. Besides a microphone, the sensory glove also includes a gyroscope and three accelerometers that provide valuable information to allow the selection of the appropriate signal time windows recorded by the microphone of the glove. These signal time windows are subsequently analyzed by a convolutional neural network, which indicates whether the connection of the components has been made correctly or not. The development of the system, its implementation in a production industry environment and the results obtained are analyzed.

Respiratory flows as a method for safely preventing the coronavirus transmission (COVID-19)

The spread of CoV-2 occurs mainly by respiratory droplets. Its dispersion depends on several factors: viscoelasticity of fluid, ventilation, evaporation rate, exhalations, sneeze or cough. At moment, the preventive distance to avoid the contamination has been established in 1-2 m. We believe that it is necessary to review this aspect, because the respiratory flows change with the intensity of physical activity. The ventilatory response can be evaluated in terms of ventilatory demand or ventilatory efficiency. During maximal effort tests, athletes mobilize an extraordinary amount of air arriving to 150/200 L/min. The respiratory volume follows increase in linear progression during the test in function of power developed. When the air volume is increased 10 times, we think that the distance should be around 6-7 m

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Actividad electromiográfica (EMG) durante el pedaleo, su utilidad en el diagnóstico de la fatiga en ciclistas / Electromiografic (EMG) activity during pedaling, its utility in the diagnosis of fatigue in cyclists

La fatiga muscular tiene múltiples definiciones, pero con una misión especial cual es la misión protectora, avisando al organismo sobre la debilidad o la aparición de una incapacidad funcional. En esta revisión se hace un análisis de las aplicaciones de la electromiografía (EMG) como técnica para comprender los patrones de activación musculares durante el pedaleo y la aparición de fatiga muscular. Se ha realizado una revisión en la cual se analizan las variaciones de la actividad EMG durante las fases del pedaleo. El movimiento del pedaleo ha sido estudiado exhaustivamente y se ha legado a distinguir 4 fases en el pedaleo que originan la propulsión y el recobro. Mediante el uso de la EMG se pueden describir los patrones de activación típicos, en cuanto al nivel de actividad y el tiempo de activación de los principales músculos de las extremidades inferiores. La actividad muscular y la coordinación pueden variar entre personas a lo largo de un solo ciclo de pedaleo y entre diferentes ciclos de la misma persona. También se examinan los principales factores que pueden influir en estos patrones EMG durante las fases del pedaleo. Asimismo, se describe la influencia de factores como la potencia de salida, cadencia o frecuencia de pedaleo, pendiente y postura, interfaz calzado pedal, nivel de entrenamiento y fatiga muscular, que producen alteraciones en el tiempo de activación y coordinación muscular. En conclusión, la EMG permite detectar la aparición de la fatiga muscular, bien de origen central o periférico. También, estimar el umbral de fatiga de neuromuscular a partir de la amplitud EMG durante un test incremental en un cicloergómetro. Al aumentar de la amplitud para intentar mantener la fuerza y una disminución del espectro de frecuencias

Muscle fatigue has multiple definitions, but with a special mission what is the protective mission, warning the body about weakness or the appearance of a functional disability. In this review, we present the applications of Electromyography (EMG) as a technique to gain insight into the activation patterns during cycling and the onset of fatigue. A narrative review has been carried out in which analysis of the EMG activity during the different phases of the pedal cycle. The movement of the pedal has been studied exhaustively and has been able to distinguish 4 phases in the pedaling that originate the propulsion and the recovery. By using the EMG it is possible to describe the typical activation patterns in terms of the activity level and activation time of the main muscles of the lower limbs. Muscle activity and coordination can vary between people throughout a single cycle of pedaling and between different cycles of the same person. Moreover, we examine the main factors that can influence these electromyographic patterns during the pedal cycle. We also describe the influence of factors such as output power, cadence or frequency of pedaling, slope and posture, foot pedal interface, training level and muscle fatigue that produce alterations in the time of activation and muscular coordination. In conclusion, we believe that EMG can detect the occurrence of muscle fatigue, either of central or peripheral origin. The method used to estimate the neuromuscular fatigue threshold from the EMG amplitude during an incremental test on a cycle ergometer is presented. In general there is an increase in amplitude to try to maintain the force and a decrease in the frequency spectrum

Estimation of the neuromuscular fatigue threshold from an incremental cycling test using 1-minute exercise periods.

BACKGROUND: The objectives of this study were: 1) to evaluate the method used for estimating the neuromuscular fatigue threshold from surface electromyographic amplitude (the PWCFT test) during a single incremental cycling workout using 1-minute exercise periods, and 2) to investigate the possible associations between PWCFT and metabolic (onset of blood lactate accumulation [OBLA]) and ventilatory (ventilatory threshold [VT] and respiratory compensation point [RCP]) variables. METHODS: Sixteen cyclists performed incremental cycle ergometer rides to exhaustion with bipolar surface sEMG signals recorded from the vastus lateralis. Subsequently, participants performed one constant-workload exercise test at 100% of their PWCFT. RESULTS: During the incremental test, the power output at PWCFT was not correlated with that of OBLA (P>0.05), but it was positively correlated with those of VT and RCP (P<0.05). During the constant-workload test, heart rate and blood lactate increased progressively and significantly (P<0.05), whereas sEMG amplitude remained unchanged (P>0.05). The average duration of the constant-workload exercise was 8-9 minutes. CONCLUSIONS: The application of the PWCFT method using 1-min exercise periods could lead to overestimation of the neuromuscular fatigue threshold most likely because this stage duration allows insufficient time for the sEMG response to manifest.

Influence of timing variability between motor unit potentials on M-wave characteristics.

The transient enlargement of the compound muscle action potential (M wave) after a conditioning contraction is referred to as potentiation. It has been recently shown that the potentiation of the first and second phases of a monopolar M wave differed drastically; namely, the first phase remained largely unchanged, whereas the second phase underwent a marked enlargement and shortening. This dissimilar potentiation of the first and second phases has been suggested to be attributed to a transient increase in conduction velocity after the contraction. Here, we present a series of simulations to test if changes in the timing variability between motor unit potentials (MUPs) can be responsible for the unequal potentiation (and shortening) of the first and the second M-wave phases. We found that an increase in the mean motor unit conduction velocity resulted in a marked enlargement and narrowing of both the first and second M-wave phases. The enlargement of the first phase caused by a global increase in motor unit conduction velocities was apparent even for the electrode located over the innervation zone and became more pronounced with increasing distance to the innervation zone, whereas the potentiation of the second phase was largely independent of electrode position. Our simulations indicate that it is unlikely that an increase in motor unit conduction velocities (accompanied or not by changes in their distribution) could account for the experimental observation that only the second phase of a monopolar M wave, but not the first, is enlarged after a brief contraction. However, the combination of an increase in the motor unit conduction velocities and a spreading of the motor unit activation times could potentially explain the asymmetric potentiation of the M-wave phases.

Limitations of Spectral Electromyogramic Analysis to Determine the Onset of Neuromuscular Fatigue Threshold during Incremental Ergometer Cycling.

Recently, a new method has been proposed to detect the onset of neuromuscular fatigue during an incremental cycling test by assessing the changes in spectral electromyographic (sEMG) frequencies within individual exercise periods of the test. The method consists on determining the highest power output that can be sustained without a significant decrease in spectral frequencies. This study evaluated the validity of the new approach by assessing the changes in spectral indicators both throughout the whole test and within individual exercise periods of the test. Fourteen cyclists performed incremental cycle ergometer rides to exhaustion with bipolar surface EMG signals recorded from the vastus lateralis. The mean and median frequencies (Fmean and Fmedian, respectively) of the sEMG power spectrum were calculated. The main findings were: (1) Examination of spectral indicators within individual exercise periods of the test showed that neither Fmean nor Fmedian decreased significantly during the last (most fatiguing) exercise periods. (2) Examination of the whole incremental test showed that the behaviour of Fmean and Fmedian with increasing power output was highly inconsistent and varied greatly among subjects. (3) Over the whole incremental test, half of the participants exhibited a positive relation between spectral indicators and workload, whereas the other half demonstrated the opposite behavior. Collectively, these findings indicate that spectral sEMG indexes do not provide a reliable measure of the fatigue state of the muscle during an incremental cycling test. Moreover, it is concluded that it is not possible to determine the onset of neuromuscular fatigue during an incremental cycling test by examining spectral indicators within individual exercise periods of the test. Key pointsThe behaviour of spectral EMG indicators during the incremental test exhibited a high heterogeneity among individuals, with approximately half of the participants showing a positive relation between spectral indicators and workload and the other half showing the opposite behaviour.None of the spectral EMG indicators examined (Fmean nor Fmedian) decreased significantly between the ventilatory threshold and the highest power output.Examination of spectral indicators within individual exercise periods of the test showed that neither Fmean nor Fmedian decreased significantly during the last (most fatiguing) exercise periods.

Physiological Responses during Cycling With Oval Chainrings (Q-Ring) and Circular Chainrings.

The aim of this study was to compare the physiological responses of cyclists using round (C-ring) or oval (Q-ring) chainrings during an incremental test until exhaustion. Following a randomized design, twelve male elite cyclists [age (mean ± SD): 21.1 ± 2.1 yr; VO2max: 78.1 ± 5.3 mL·kg(-1)min(-1)] performed two incremental maximal tests separated by 48 h (one with C-rings, the other with Q-rings). Starting at 100 W, the workload was increased by 25 W every 3 min until volitional exhaustion. Maximal heart rate, power output and oxygen consumption were compared. Blood lactate was monitored throughout the test. After the incremental test, 4 intermittent 20-s maximal sprints with a 60-s recovery period in between were performed. Maximal isometric voluntary contractions were performed at rest and immediately after each 20-s maximal sprint, and the force and EMG RMS amplitude were recorded from the vastus medialis and vastus lateralis muscles. For the incremental exercise test, no significant differences were found in the maximal power output (P=0.12), oxygen consumption (P=0.39), and heart rate (P=0.32) between Q-rings and C-rings. Throughout the incremental test, lactate levels were comparable when using both the C-rings and Q-rings (P=0.47). During the short sprints, power output was 2.5-6.5% greater for Q-rings than for C-rings (P=0.22). The decline in EMG RMS amplitude observed during the incremental tests was comparable for Q-rings and C-rings (0.42). These findings indicate that the oval chainring design, presented here as "Q-rings", did not significantly influence the physiological response to an incremental exercise test as compared to a conventional chainring. Key pointsDuring the incremental exercise test, no significant differences were found in power output, oxygen consumption or heart rate between oval "Q-rings" and conventional chainrings.Over the course of the incremental test, blood lactate levels were comparable for the oval "Q-rings" and conventional chainrings.During the short sprints performed after the incremental test, there were no statistical differences in power production between oval "Q-rings" and conventional chainrings.

Effects of changes in the shape of the intracellular action potential on the peak-to-peak ratio of single muscle fibre potentials.

In situ recording of the intracellular action potential (IAP) of human muscle fibres is not yet feasible, and consequently, knowledge about certain IAP characteristics of these IAPs is still limited. The ratio between the amplitudes of the second and first phases (the so-called peak-to-peak ratio, PPR) of a single fibre action potential (SFAP) is known to be closely related to the IAP profile. The PPR of experimentally recorded SFAPs has been found to be largely independent of changes in the fibre-to-electrode (radial) distance. The main goal of this paper is to analyze the effect of changes in different aspects of the IAP spike on the relationship between PPR and radial distance. Based on this analysis, we hypothesize about the characteristics of IAPs obtained experimentally. It was found that the sensitivity of the SFAP PPR to changes in radial distance is essentially governed by the duration of the IAP spike. Assuming that, for mammals, the duration of the IAP rising phase lies within the range 0.2-0.4ms, we tentatively suggest that the duration of the IAP spike should be over approximately 0.75ms, with the shape of the spike strongly asymmetric. These IAP characteristics broadly coincide with those observed in mammal IAPs.