Frequency Of Limb Movements Research Articles

Anticipatory regulation of cardiovascular system on the emergence of auditory-motor interaction in young infants.

Humans develop auditory-motor interaction to produce a variety of rhythmic sounds using body movements, which are often produced and amplified with tools, such as drumming. The extended production of sounds allows us to express a wide range of emotions, accompanied by physiological changes. According to previous studies, even young infants enhance movements in response to auditory feedback. However, their exhibition of physiological adaptation on the emergence of auditory-motor interaction is unclear. We investigated the movement and cardiac changes associated with auditory feedback to spontaneous limb movements in 3-month-old infants. The results showed that infants increased the frequency of limb movements inducing auditory feedback, while they exhibited a more regular rhythm of the limb movements. Furthermore, heart rate increase associated with the limb movement was first inhibited immediately after the timing of the auditory feedback, which may reflect sustained attention to the auditory stimuli. Then, through auditory-motor experience, the heart rate increase was inhibited even prior to the auditory feedback, leading to suppression of the peak intensity of the heart rate increase. These findings suggest that young infants regulate the cardiovascular system as well as limb movements in anticipation of the auditory feedback. The anticipatory regulation associated with movement and attentional changes may contribute to reduced cardiovascular stress in auditory-motor interaction, and provide a developmental basis for more sophisticated goal-directed behavior of producing rhythmic sounds.

A lead-free stretchable piezoelectric composite for human motion monitoring

So far, many kinds of piezoelectric composite have been developed to prepare flexible motion sensors. However, some lead-based materials are harmful to human body and cannot be used for motion posture detection, despite their excellent performances. In this work, a lead-free stretchable piezoelectric composite is developed by introduce BaTiO3 (BTO) powder into silicone rubber matrix. The peak-to-peak values of the voltage and current can reach up to 38 V and 0.8 μA under the periodic stretching excitation. It can respond to different strain stimulations. When fixed on the body, it can effectively detect the angle and frequency of limb movement, suitable as human motion sensor. The flexible stretchable composite provides a good solution for wearable piezoelectric devices.

An anthropometric study for the anthropomorphic design of tomato-harvesting robots

To explore how humans can dexterously pick fruits of various sizes from a tomato plant from different positions and postures, some anthropometric dimensions related to the hand-harvesting of the fruits were determined within 261 volunteers, and their correlations were investigated using a bivariate correlation analysis method. The heights of the body (stature), shoulder tip, waist and knee of participants ranged from 111.2 to 193.6, 87.5 to 163.0, 62.1 to 117.3, and 31.0 to 56.0 cm, respectively; the ratios of the knee height, waist height, and shoulder tip height to the stature were 0.25–0.33, 0.52–0.65, and 0.76–0.87, respectively; the shoulder tip breadth, upper limb length and foot length of participants ranged from 26.0 to 48.5, 45.4 to 85.6, and 19.5 to 28.0 cm, respectively; and the length ratios of the hand, forearm, and upper arm to the upper limb were 0.23–0.31, 0.29–0.38, and 0.35–0.45, respectively. There were high linear correlations among the stature, waist height and knee height, between the forearm and hand lengths, and among the stature, hand length and arm length and moderate linear correlations between most hand dimensions. These human body dimensions determine the upper limb workspace, body balance, working comfort and lower limb movement frequency during picking, and this information will be useful for the bionic dimensional synthesis design of a harvesting robotic arm, walking mechanism and body. The results of multiple comparisons in ANOVA showed that there were significant differences between some of the finger dimensions and between some of the hand-scaling dimensions, which is one of the main features enabling the human hand to pick various sizes of fruits. This study can provide guidance and inspiration for the anthropomorphic design of robotic tomato-harvesting end-effectors.

The effects of diltiazem on growth, reproduction, energy reserves, and calcium-dependent physiology in Daphnia magna

With the growth of both the pharmaceutical industry and the human population and longevity, more drugs are used and processed each day. Inevitably, these pharmaceuticals enter wastewater through human excretion and improper disposal of leftovers. One such medication, diltiazem, a calcium channel blocker, is of importance due to its widespread consumption, and prevalence in aquatic environments. To study the sub-lethal effects of diltiazem on aquatic animals, we investigated its impacts no feeding behaviour, heart rate, respiration, growth, and reproduction of a bioindicator species, Daphnia magna. When exposed to environmentally relevant concentrations, D. magna increased their heart rate by 12% and oxygen consumption by 48%. However, exposure did not have any effects on thoracic limb movement frequency or peristalsis (i.e. feeding behaviour). Individuals exposed to diltiazem for a longer duration (16 days) showed a 44% decrease in lipid reserves and produced between 17 and 28% fewer neonates which were 10–12% larger. Our study demonstrated that exposure to diltiazem creates an energy imbalance in D. magna which could, in the long run, influence their populations.

Limb movement frequency is a significant modulator of the ventilatory response during submaximal cycling exercise in humans

Human experimentation investigating the contribution of limb movement frequency in determining the fast exercise drive to breathe has produced controversial findings. To evaluate the role of limb movement frequency in determining the fast exercise drive to breathe, endurance runners and recreationally-active controls performed two sinusoidal exercise protocols on a cycle ergometer. One protocol was performed at constant workload with sinusoidal pedaling cadence, and a second with sinusoidal workload at constant cadence. Metabolic rate (VO2) increases and means were matched between these two experiments. The ventilatory response was significantly faster when limb movement speed was varied, compared to when pedal loading was varied (18.49±15.6s vs. 50.5±14.5s, p<0.05). Ventilation response amplitudes were significantly higher during pedal cadence variation versus pedal loading variation (3.99±0.25 vs. 2.58±0.17L/min, p<0.05). Similar findings were obtained for endurance athletes, with significantly attenuated ventilation responses to exercise versus control subjects. We conclude that fast changes in limb movement frequency are a potent stimulus for ventilation at submaximal workloads, and that this response is susceptible to attenuation through training.

Recent advances in understanding mechanisms regulating breathing during exercise

Recent advances in understanding mechanisms regulating breathing during exercise

The fast exercise drive to breathe

This paper presents a personal view of research into the exercise drive to breathe that can be observed to act immediately to increase breathing at the start of rhythmic exercise. It is based on a talk given at the Experimental Biology 2013 meeting in a session entitled ‘Recent advances in understanding mechanisms regulating breathing during exercise’. This drive to breathe has its origin in a combination of central command, whereby voluntary motor commands to the exercising muscles produce a concurrent respiratory drive, and afferent feedback, whereby afferent information from the exercising muscles affects breathing. The drive at the start and end of rhythmic exercise is proportional to limb movement frequency, and its magnitude decays as exercise continues so that the immediate decrease of ventilation at the end of exercise is about 60% of the immediate increase at the start. With such evidence for the effect of this fast drive to breathe at the start and end of rhythmic exercise, its existence during exercise is hypothesised. Experiments to test this hypothesis have, however, provided debatable evidence. A fast drive to breathe during both ramp and sine wave changes in treadmill exercise speed and grade appears to be present in some individuals, but is not as evident in the general population. Recent sine-wave cycling experiments show that when cadence is varied sinusoidally the ventilation response lags by about 10 s, whereas when pedal loading is varied ventilation lags by about 30 s. It therefore appears that limb movement frequency is effective in influencing ventilation during exercise as well as at the start and end of exercise.

Time‐frequency mapping of the rhythmic limb movements distinguishes convulsive epileptic from psychogenic nonepileptic seizures

A definite diagnosis of psychogenic nonepileptic seizures (PNES) usually requires in-patient video-electroencephalography (EEG) monitoring. Previous research has shown that convulsive psychogenic nonepileptic seizures (PNES) demonstrate a characteristic pattern of rhythmic movement artifact on the EEG. Herein we sought to examine the potential for time-frequency mapping of data from a movement-recording device (accelerometer) worn on the wrist as a diagnostic tool to differentiate between convulsive epileptic seizures and PNES. Time-frequency mapping was performed on accelerometer traces obtained during 56 convulsive seizure-like events from 35 patients recorded during in-patient video-EEG monitoring. Twenty-six patients had PNES, eight had epileptic seizures, and one had both seizure types. The time-frequency maps were derived from fast Fourier transformations to determine the dominant frequency for sequential 2.56-s blocks for the course of each event. The coefficient of variation (CoV) of limb movement frequency for the PNES events was less than for the epileptic seizure events (median, 17.18% vs. 52.23%; p < 0.001). A blinded review of the time-frequency maps by an epileptologist was accurate in differentiating between the event types, that is, 38 (92.7%) of 41 and 6 (75%) of 8 nonepileptic and epileptic seizures, respectively, were diagnosed correctly, with seven events classified as "nondiagnostic." Using a CoV cutoff score of 32% resulted in similar classification accuracy, with 42 (93%) of 45 PNES and 10 (91%) of 11 epileptic seizure events correctly diagnosed. Time-frequency analysis of data from a wristband movement monitor could be utilized as a diagnostic tool to differentiate between epileptic and nonepileptic convulsive seizure-like events.

Changes in exercise hyperpnea are more attributable to limb movement frequency than pedal loading

The significance of limb movement frequency in determining ventilation during exercise remains a contested topic in respiratory research. We used two sinusoidal exercise protocols on a cycle ergometer to separately assess the effects of limb movement frequency i.e. cadence (CP) and pedal load (LP) on ventilation. During the first test, cadence was altered sinusoidally while pedal load remained constant. In the second test, pedal load changed sinusoidally while cadence was constant. Variables were fitted to a sinusoid with parameters amplitude, mean, period, and phase angle lag. Five participants completed both protocols. Mean (SD) cadence amplitudes differed between protocols (CP: 23.5 (0.67) rpm, LP: 0.47 (0.3) rpm, p&lt;0.001). The phase lag angles for ventilation also differed, with sinusoidal cadence significantly smaller than sinusoidal load (CP: 23.7 (12.7) deg., LP: 48.1 (14.6) deg., p= 0.023). However the mean ventilation was not different between tests (CP: 44.5 (3.9) L/min, LP: 46.8 (4.2) L/min, p=0.99). VO2 and VCO2 did not differ between tests; eliminating the possibility that changes in ventilatory response between protocols resulted from differences in metabolism. Therefore we concluded that changes in exercise hyperpnea are more attributable to limb movement frequency than pedal loading.Funding provided by the Faculty of Kinesiology and Physical Education at the University of Toronto

The ventilatory response to sine wave variation in exercise loads and limb movement frequency

The current study's experiments tested the hypothesis that limb movement frequency is a significant determinant of exercise hyperpnoea. To this end, 19 healthy participants walked on a treadmill, where work was varied sinusiodally by alterations in either treadmill speed or grade. Measured responses were fitted with sine waves to determine their amplitudes and phase angles. Walking pace amplitude was greater during speed tests than grade tests, and phase lag relative to the treadmill smaller, as expected. Ventilation, carbon dioxide production, and oxygen uptake amplitudes were higher during speed tests than grade tests. Further, phase angle lags relative to the treadmill for these measures were shorter during speed tests than grade tests. We concluded that these findings demonstrate the presence of changes in breathing during exercise that can be attributed to changes in limb movement frequency.

Comment on Point:Counterpoint “Supraspinal locomotor centers do/do not contribute significantly to the hyperpnea of dynamic exercise in humans”

The following letters are in response to the Point:Counterpoint series “Supraspinal locomotor centers do/do not contribute significantly to the hyperpnea of dynamic exercise in humans” that appeared in the March issue (vol. 100: 1087–1083, 2006; <http://jap.physiol.org/content/vol100/issue3/

Aquatic and terrestrial locomotory energetics in a toad and a turtle: a search for generalisations among ectotherms.

Murray short-necked turtles were trained to walk on a motorised treadmill and to swim in a recirculating flume. Through filmed records, the frequency of limb movement and the time that thrust was directed against the substrate were measured. The animals wore masks when walking and accessed air when swimming from a ventilated capsule placed on top of the water surface. Measurement of the exhalant O(2) and CO(2) levels from these devices enabled the measurement of metabolic rates. Equivalent data were obtained from swimming and hopping cane toads, although repeatable measures of limb frequency and contact times were not obtained due to the intermittent form of locomotion in this species. Comparing the cost of transport, the energy required to transport a mass of animal over a unit distance, with other animals showed that toads do not have a cheap form of terrestrial locomotion, but turtles do; turtles use half the cost predicted from their body mass. This economy of locomotion is consistent with what is known about turtle muscle, the mechanics of their gait, and the extremely long contact time for a limb with the substrate. Swimming in toads is energetically expensive, whereas turtles, on the basis of mass, use about the same energy to transport a unit mass as an equivalent-size fish. The data were compared with the predictions of the Kram-Taylor hypothesis for locomotory scaling, and walking turtles were found to provide a numerical fit. The data show that both terrestrial and aquatic locomotory energetics in toads are generally higher than predictions on the basis of mass, whereas in turtles they are lower.

Changes in intra-abdominal pressure during postural and respiratory activation of the human diaphragm.

In humans, when the stability of the trunk is challenged in a controlled manner by repetitive movement of a limb, activity of the diaphragm becomes tonic but is also modulated at the frequency of limb movement. In addition, the tonic activity is modulated by respiration. This study investigated the mechanical output of these components of diaphragm activity. Recordings were made of costal diaphragm, abdominal, and erector spinae muscle electromyographic activity; intra-abdominal, intrathoracic, and transdiaphragmatic pressures; and motion of the rib cage, abdomen, and arm. During limb movement the diaphragm and transversus abdominis were tonically active with added phasic modulation at the frequencies of both respiration and limb movement. Activity of the other trunk muscles was not modulated by respiration. Intra-abdominal pressure was increased during the period of limb movement in proportion to the reactive forces from the movement. These results show that coactivation of the diaphragm and abdominal muscles causes a sustained increase in intra-abdominal pressure, whereas inspiration and expiration are controlled by opposing activity of the diaphragm and abdominal muscles to vary the shape of the pressurized abdominal cavity.

Activation of the human diaphragm during a repetitive postural task.

The co-ordination between respiratory and postural functions of the diaphragm was investigated during repetitive upper limb movement. It was hypothesised that diaphragm activity would occur either tonically or phasically in association with the forces from each movement and that this activity would combine with phasic respiratory activity. Movements of the upper limb and ribcage were measured while standing subjects performed repetitive upper limb movements 'as fast as possible'. Electromyographic (EMG) recordings of the costal diaphragm were made using intramuscular electrodes in four subjects. Surface electrodes were placed over the deltoid and erector spinae muscles. In contrast to standing at rest, diaphragm activity was present throughout expiration at 78 +/- 17% (mean +/- s.d.) of its peak inspiratory magnitude during repeated upper limb movement. Bursts of deltoid and erector spinae EMG activity occurred at the limb movement frequency (approximately 2.9 Hz). Although the majority of diaphragm EMG power was at the respiratory frequency (approximately 0.4 Hz), a peak was also present at the movement frequency. This finding was corroborated by averaged EMG activity triggered from upper limb movement. In addition, diaphragm EMG activity was coherent with ribcage motion at the respiratory frequency and with upper limb movement at the movement frequency. The diaphragm response was similar when movement was performed while sitting. In addition, when subjects moved with increasing frequency the peak upper limb acceleration correlated with diaphragm EMG amplitude. These findings support the argument that diaphragm contraction is related to trunk control. The results indicate that activity of human phrenic motoneurones is organised such that it contributes to both posture and respiration during a task which repetitively challenges trunk posture.

Neural drives to breathing during exercise.

This article presents the author's views about the neural drives to breathing during exercise. Two hypotheses are developed, the first being that the rapid changes in ventilation at the start and end of exercise are due to a fast neural drive whose magnitude is related to the frequency of limb movement. Experimental data are presented that this drive persists throughout exercise but declines as exercise continues. Second, the excessive increase in ventilation that occurs above the first ventilatory threshold during an incremental exercise test is due to a heavy exercise neural drive whose magnitude is related to the motor commands to the exercising muscles. Using the electromyographical activity of the working muscles as an index of the strength of the motor commands, experimental evidence is presented showing the coincidence of the first ventilatory threshold and that for the electromyographic activity of the working muscles during incremental exercise tests.

Changes in ventilation in response to ramp changes in treadmill exercise load.

These experiments examined the changes in ventilation during a 40-s ramp increase in exercise load, produced by increasing either the speed of the treadmill or the grade, to equivalent end-points of oxygen uptake. Six subjects underwent five trials each for grade and speed, while ventilation was monitored breath-by-breath. For each subject, ventilation versus time for all five of the speed trials was plotted on a single graph and fitted by linear regression. The data for the grade trials were similarly treated. For all subjects, the slope of the regression line for the speed plots was found to be significantly (P < 0.05) greater than that for the grade plots. We concluded that these experimental results support the hypothesis that the neural drive to ventilation persists as exercise continues and is proportionately related to the frequency of limb movement.

Aerobic metabolic requirements of simulated cross-country skiing.

This study evaluated the aerobic metabolic requirements of simulated cross-country skiing. Five male subjects exercised on a cross-country skiing machine at 12 different arm and leg resistances and movement frequencies. Oxygen consumption (VO2) ranged from 21.6 to 44.4 ml kg(-1) min(-1). The VO2 increased significantly (p less than 0.05) as the frequency of limb movement was increased. These data suggest that simulated cross-country skiing places a significant demand on the aerobic metabolic system and as such is a viable alternative to conventional cardiovascular exercise modalities.

Effects of Changes in Locomotor Intensity, Hypoxia and Hypercapnia on Locomotorrespiratory Synchrony During Walking/Running in Canada Geese

ABSTRACT To examine the effects of locomotor frequency and respiratory drive on the incidence of locomotor-respiratory coupling (i.e. entrainment), we examined the relationship between locomotor and ventilatory patterns in trained Canada geese that were: (1) running at three speeds (0·40, 0·52 and 0·72ms-1) on a treadmill, (2) free-running at three velocity intervals (0·40–0·72, 1·0–1·5 and 1·5–2·0ms-1) overground, and (3) breathing hypoxic (12 % O2/l % CO2) and hypercapnic (5 % CO2/30% O2) gas mixtures while running at one speed (0·52ms-1) on the treadmill. The portion of the time that the locomotor and respiratory systems were coupled was significantly greater during overground locomotion (41·1 ±3·2%) than at comparable speeds on the treadmill (29·0 ±2·6%). In addition, a significant increase in coupling with velocity was only observed during overground locomotion (41·1 ±3·2% at 0·40–0·72ms-1 vs 57·7 ±6·3% at 1·5–2·0ms-1). This increase in entrainment appeared to be the direct result of an increase in locomotor frequency per se and not due to the increase in metabolic rate associated with greater locomotion velocity. The effects of hypercapnia on the degree of entrainment were unclear owing to inter-animal variability; however, hypoxia caused a substantial decrease in entrainment from air-breathing values (34·8 ± 3·9 %) to levels not different from those possible due to chance alone (20%). Thus, it appears that locomotor pattern does entrain ventilatory rhythm and that the degree of entrainment is partially dependent on limb movement frequency. However, the increased respiratory drive associated with hypoxia appears to override the influence of locomotor rhythm on respiratory pattern, with a subsequent decrease in entrainment.

Ventilatory responses during varied stride and pedal frequencies

The effects of limb movement frequency during walking and running and cycling at 60 and 90 rpm on the ventilatory responses were studied in 19 male subjects. Ten of the subjects were trained runners whereas nine of the subjects were trained cyclists. The runners completed walk and run exercise trials at equal levels of CO 2 excretion (V̇ CO 2 ) and low (≈60) rpm and high (≈90) rpm cycling trials at equal V̇ CO 2 levels. The cyclists completed low and high rpm cycling trials at equal V̇ CO 2 levels. The cyclists were not tested on the walk/run trials as they had been tested previously and had been shown to have similar ventilatory responses when walking and running at equal V̇ CO 2 levels. Minute ventilation (V̇ e), tidal volume (V t), breathing frequency (f), end-tidal CO 2 ( Pet CO 2 )_tensions, and inspiratory (T i) and expiratory (T e) times were not found to differ significantly between the low and high pedal frequency trials for either the cyclists or the runners. No significant differences were found in estimated arterial CO 2 tensions (Pa CO 2 ) or estimated alveolar ventilation (V̇ a) between the cycling trials for either the runners or the cyclists. When comparing running to walking, the runners were found to have a greater V̇ e and estimated V̇ a. This was mediated by an increase in f as V t was found to decrease. The increased f was associated with a shortened T i as T e was not significantly different between the walk and run trials. End-tidal CO 2 tension and estimated Pa CO 2 was significantly lower during the run trial as compared to the walk trial. These results suggest some form of neurogenic stimuli influencing ventilation in the runners while running. This same neurogenic influence is not present when cyclists run and when either cyclists or runners exercise on the bicycle. A possible source for the neurogenic stimuli is discussed.

Patterns of movement in the first 6 months of life: New directions.

The field of infant perceptual development has relied heavily on the preferential-looking and habituation paradigms. Despite the obvious advantages of employing standardized methodologies, there is a need to study how perceptual variables give rise to and guide action beginning in the neonatal period. It is argued here that, in the first 5 months of life, it is important to distinguish reflexive patterns of movement from voluntary and cortically controlled patterns. Some criteria are defined. This paper describes three experiments which utilized movement counters to record developmental changes in the frequency and synchrony of limb movements in infants under 5 months. The results show that there is a general increase in frequency of limb movements from 1 to 5 months, but with a plateau or even a decrease in activity from the middle of the third month to the end of the fourth month. It was also demonstrated that synchrony scores (co-activation) for pairs of limbs showed significant increases from 1 month to 5 months. Finally, in all three experiments the presentation of an attractive toy resulted in suppression of activity. The results of the three experiments are interpreted to measure a gradual increase in cortically controlled movement patterns.