Fractionated Reaction Time Research Articles

Reaction time and muscle activation patterns in elite and novice athletes performing a taekwondo kick

ABSTRACT Fractionated reaction time can be used to determine distinct epochs known as pre-motor, response and movement times (MTs) of a reaction time task. The purpose of this study was to compare elite and novice athletes performing a taekwondo kick in terms of the fractionated reaction time and electromyography (EMG) activation patterns of the muscles of the striking lower limb and the lower back. We hypothesised that the pre-motor time, response time (RT) and MT would be the shorter for elite athletes compared to novices. We collected data on 13 elite and 10 novice athletes when performing a roundhouse kick. The experiment included EMG electrodes placed on five low back and lower extremity muscles and an electrogoniometer placed on the kicking knee. We found that pre-motor time was shorter and the RT was longer for elite athletes than novice athletes. Moreover, the integrated EMG of the main knee extensor does not differ between groups though other leg and trunk muscles do. The results allow coaches and teachers to understand this particular taekwondo kicking movement which could ultimately improve the technique in order to establish training and teaching goals.

In Memoriam

In Memoriam

Chronic stroke and aging: The impact of acoustic stimulus intensity on fractionated reaction time

In control samples, intense acoustic “go” stimuli accelerate the central and peripheral motor processes that compose simple reaction time movements. The goal of the current study was to determine whether movements that are initiated to intense acoustic cues facilitate simple reaction times in (1) adults with chronic stroke as compared to age matched controls and (2) in older as compared to younger adults. EMG and force data were collected from three groups (stroke, older adults, and younger adults) during a ballistic wrist and finger extension task. Movements were made to the onset of 80dB and 107dB acoustic cues and simple reaction times were fractionated into premotor and motor components. The present findings offer two important contributions to the literature. First, increases in stimulus intensity led to faster motor times in the impaired limb of stroke subjects. Second, increased stimulus intensity led to faster premotor reaction times across all groups, although an age rather than a stroke-specific motor deficit was evidenced, with the younger control group displaying significantly faster premotor times. Findings are integrated with previous evidence concerning post stroke corticospinal tract integrity and are interpreted via mechanisms which address stroke and age-related changes in motoneurons and activity in motor units.

Explosive Force and Fractionated Reaction Time in Elderly Low- and High-Active Women

Explosive Force and Fractionated Reaction Time in Elderly Low- and High-Active Women

Explosive Force and Fractionated Reaction Time in Elderly Low- and High-Active Women

The purpose of this study was to determine whether muscle power, activation time, and neuromuscular stimulation are related to physical activity patterns in older women. Forty women (65-84 yr) were assigned to high-active (HA) and low-active (LA) groups on the basis of a historical activity questionnaire, and then they performed a series of maximal, voluntary, isometric knee extensions in a visually cued RT task. Fractionated RT measures were taken using three landmarks in the data: the presentation of the visual stimulus, the beginning of the EMG burst, and the initiation of force development. The rate and magnitude of neural stimulation were taken from surface EMG. Peak torque was 15% greater, rate of torque development was 26% greater, motor time was 17% shorter, rate of EMG rise was 25% faster, and onset EMG magnitude was 15% greater in HA than in LA subjects (P<0.05). These results indicate that older women with a history of vigorous activity can generate greater force, power, and motor output in comparison with their less active peers. The lower-body mass index of the HA subjects and 310% greater volume of physical activity are likely to account for the enhanced neuromuscular function seen. It is plausible that in addition to aging, physical inactivity is responsible for a large portion of the loss of neuromuscular function seen in older adults.

Explosive Force Production and Fractionated Reaction Time in Elderly Low and High Active Women

A decrease in muscle mass and muscle power, as well as increased movement time with aging have been linked to increased fall risk and inability to perform activities of daily living. PURPOSE: The purpose of this study was to provide evidence that muscle power, the time course of muscle activation, and the neurological stimulation of muscle are directly related to physical activity patterns in older women. METHODS: 40 women between 65 and 84 years were assigned to High Active (HA, n=20) and Low Active (LA, n=20) groups based on a historical activity questionnaire and then performed a series of maximal, voluntary, isometric knee extensions. A reaction time task cued by a visual stimulus was used to measure total reaction time (RT), premotor time (PMT), motor time (MT), rate of torque development (RTD), peak torque (PT), and the rate (RER) and magnitude of initial EMG (oEMG). Torque output from the isokinetic dynamometer and surface EMG were sampled at 1000Hz using a data acquisition system and were analyzed offline using visual inspection of the data. RESULTS: Body mass normalized PT was 15% greater in the HA group (1.82 ± 0.48 Nm·kg-1)than in the LA group (1.54 ± 0.34 Nm·kg-1, p=0.042). Body mass normalized RTD was 26% greater in the HA group (9.4 ±3.1 Nm·s-1·kg-1) than in the LA group (7.0 ± 2.2 Nm·s-1·kg-1, p=0.008). There were no differences between the HA and LA groups for RT (.336 ± .04s, .361 ± .06s, p=. 12) or PMT (235 ± 40 ms, 244 ± 50ms, p=0.578). MT was 17% longer in the LA group (117 ± 20 ms) when compared to the HA group (100 ± 20 ms, p=0.006). The RER was 25% faster in the HA group (547 ± 172 %pEMG·s-1) than in the LA group (413 ± 50 %pEMG·s-1, p=0.039) and the normalized oEMG was 15% greater in the HA group (107 ± 32%) when compared to the LA group (91 ± 17%, p=0.048). CONCLUSION: These results indicate that older women with a history of vigorous activity can generate greater force, power, and motor output when rapid increases in muscle force are needed in comparison to their less active peers. This can be due to a number of factors including greater muscle mass, a better ability to recruit available motor units, increased motor unit firing rate, and lower fat mass relative to muscle mass in the active group. The lower body mass index of the HA group and 300% greater volume of activity are likely to account for the enhanced neuromuscular function seen in this group.

The Inverted-U Relationship between Arousal and Fractionated Reaction Time

The Inverted-U Relationship between Arousal and Fractionated Reaction Time

Choice Reaction Time Difference Between Gender and Hand Using the Fractionated Reaction Time Technique

A gender difference in choice reaction time (RT) has been reported in the literature (e.g., Adam et al., 1999; Noble et al., 1964). Noble, Baker and Jones found that females had slower choice RT than their male counterparts many years ago. Later study by Adam et al. also reported a faster choice RT for male participants. Since Weiss (1965) introduced the measurement of RT components with electromyography (EMG), pre-motor time (PMT) and motor time (MT) have been used to identify the central (cognitive) and peripheral (neuromuscular) processing of the initiation of voluntary movement in human performance research. PURPOSE: To examine whether choice reaction time and its fractionated components differ between genders and dominant and non-dominant hands. METHODS: Twenty right-hand dominant college students (10 male, 26.0 ± 3.06 yrs; 10 female, 25.4 ± 2.27 yrs) were tested for their visual-manual choice reaction time for four consecutive days using both left and right hands. Based on the EMG activity of the pronator teres and biceps brachii, fractionated RTs of pronation and supination were measured for each hand. The learning effect was identified and a reliable measure was obtained. A 2 (gender) by 2 (hand) two-way mixed design analysis of variance (ANOVA) was used to analyze possible gender and hand difference as well as their interaction. RESULTS: Choice RT decreased across days (p < .05), however, no significant change was found between days 3 and day 4. No Gender x Hand interaction or hand difference was observed for choice RT. A significant gender difference was observed for total choice RT (F1,18 = 6.43, p < .05). The mean choice RT for the males was 278 ms, and for the females it was 308 ms. A further analysis of PMT and MT indicated that male participants had a faster PMT (218 ms) than female (246 ms) participants (F1,18 = 6.51, p < .05), but no MT difference was observed between the gender groups. CONCLUSIONS: There is no choice reaction time difference between dominant and non-dominant hands for the college students. Male participants demonstrated a faster choice RT than female participants, and the difference in total choice RT can be attributed to the PMT component, but not MT. The finding supports the proposed explanations that males might have employed a binary strategy while females used a serial strategy in choice reaction time tasks.

Fractionated Reaction Time in Attention Deficit and Hyperactivity Disorder Children

Fractionated Reaction Time in Attention Deficit and Hyperactivity Disorder Children

Stimulus–Response Compatibility and Response Preparation: Effects on Motor Component of Information Processing for Upper and Lower Limb Responses

The effects of stimulus-response compatibility and response preparation on the motor component of the information processing system were investigated by analyzing the fractionated reaction time for the upper and lower limbs. The reaction time was divided into two periods with respect to the onset of electromyographic activity, premotor and motor times. The response preparation was manipulated by the probability that the locations of the precue and subsequent imperative stimulus corresponded. On a stimulus-response compatible task, subjects were required to release a key on the same side as an imperative stimulus, irrespective of the precued side. On an incompatible task, subjects were required to act in the reverse manner. The upper and lower limb responses were measured during both tasks. A repeated-measures design was used with 12 male university students. Analysis of the reaction and premotor times indicated that the stimulus-response compatibility effect became larger as response preparation decreased. The analysis of motor time yielded significant interactions between stimulus-response compatibility and limb and between response preparation and limb. These findings indicated that the motor component of information processing for the lower limb response is affected by both stimulus-response compatibility and response preparation.

Behaviorally Fractionated Reaction Time to an Omitted Stimulus: Tests with Visual, Auditory, and Tactile Stimuli

Two experiments tested the adequacy of behavioral criteria to fractionate reaction time (RT) into independent premotor (cognitive) and motor components. Healthy participants performed an omitted stimulus reaction time task in which they responded to the termination of a train of lateralized visual, auditory or tactile stimuli. Exp. 1 with 48 participants (24 men) showed premotor RT was independent of motor RT in each sensory modality and did not differ as a function of side of presentation or sex. Repeated tests administered in Exp. 2 (N= 12) also showed no significant association between the behaviorally fractionated measures. These results are comparable to those obtained using muscle potential to fractionate RT and suggest behaviorally fractionated premotor and motor RT could be a reliable, useful tool in the assessment of cognitive and motor processing in different sensory modalities of healthy people or those with brain injury, disease, or drug-induced disturbances.

Fractionated Reaction Time Components Vary as a Function of Movement Direction and Learning

Fractionated Reaction Time Components Vary as a Function of Movement Direction and Learning

Fractionated Reaction Time Components Vary as a Function of Movement Direction and Learning

Fractionated Reaction Time Components Vary as a Function of Movement Direction and Learning

Fractionated reaction time as a function of magnitude of force in simple and choice conditions.

The present study examined whether varying magnitude of force required to perform an isometric response influences fractionated reaction time in simple and choice conditions and whether reaction time and premotor time to initiate the response are shorter when force is selected freely by the subject than when it is selected by the experimenter. 20 subjects were required to react and produce a designated peak force as quickly and accurately as possible by squeezing a handle after a reaction signal. Four different magnitudes of force were 30, 50, and 70% of the maximum grip strength of the subjects and subject-selected magnitude of force. Reaction time and premotor time did not change across the range of forces examined in both simple and choice reaction-time conditions regardless of whether a desired force was selected by the experimenter or by the subject. These findings suggest that programming an isometric response may require a constant amount of time.

Strength training in spastic hemiparesis: should it be avoided?

Controversy exists between accepted principles of strength training and one of our popular neurological therapeutic exercise approaches. Graded resistive exercise is a common method of strength training in the general population. Bobath avoided resistive exercise with post-stroke individuals with spasticity suggesting that the use of effort would only increase cocontraction and reduce coordination. Bobath's theories remain unsupported. The purpose of this study was to test the clinical assumption that graded resistive exercise leads to loss of force production and force modulation in spastic subjects in such a way that spasticity and cocontraction increases and force control is reduced. Nine subjects with a diagnosis of stroke with left hemiplegia and evidence of spasticity in the left biceps performed graded resistive exercise with simultaneous measurements of cocontraction, spasticity levels, and fractionated reaction time. The results of this study indicated that there was little difference between the effects of graded exercise on the performance of paretic and non-paretic muscle. When differences were found, resistive exercise appeared to have a beneficial effect on the performance of paretic muscle. The results of this study suggest that graded resistive exercise is not detrimental to post-stroke spastic muscle, and should be considered as a possible remediation for the deficits of muscle weakness and reduced function in post-stroke individuals.

Effects of the similarity of required responses on fractionated reaction time.

In a previous study, Ito (1990) who used a rapid two-element force-production task, found that the simple reaction time (RT) to initiate the second element was shorter when a sequence was made up of homogeneous elements than when a sequence was made up of heterogeneous elements. The purpose of the present study was to replicate and extend the earlier experiment by adding a control condition and by fractionating RT into premotor time and motor time. Simple RT, premotor time, and motor time to initiate the first element were not different across conditions, suggesting the possibility of distributed programming of the sequence elements. The homogeneous condition, however, produced shorter simple RT and premotor time to initiate the second element than did the heterogeneous and control conditions, which were not significantly different from each other. These findings were discussed in terms of different programming demand during the RT interval.

Effects of time uncertainty and instructed muscle tension on fractionated reaction time

Abstract: An experiment was conducted to examine the effects of time uncertainty and instructed muscle tension on the reaction time of elbow flexion. Twenty‐two right‐handed subjects were asked to respond to an audio stimulus by flexing their right elbow under four conditions (2 time uncertainty × 2 instructed muscle tension). Electromyograms (EMGs) were recorded from the biceps and triceps on the subject's right side. Reaction time was divided into premotor time and motor time, based on the difference between the EMG and elbow flexion response. Analysis of reaction time showed that the effects of time uncertainty and instructed muscle tension were additive. Time uncertainty affected premotor time only, and instructed muscle tension affected motor time only. These results are discussed in terms of the assumption that premotor time is a reflection of the central nervous system and motor time is a reflection to the peripheral muscle system.

Fractionated Reaction Time in Women as a Function of Age and Physical Activity Level

Comparisons between young and older women runners and sedentary controls were examined on simple and choice reaction time tasks involving elbow flexion and extension. Reaction time was fractionated into premotor and contractile components using electromyography. Young runners were significantly faster and the older controls were significantly slower than all other groups on all reaction time tasks. The older runners were not significantly different from the young controls in any of the reaction time tasks, thus indicating that a history of running may eliminate or retard the slowing of reaction time that normally accompanies aging. All four groups had similar contractile times, indicating that the differences in reaction time were attributed to central processing in the premotor component of reaction time.

Effects of force output and preparatory period on fractionated reaction time.

The effects of force output and its preparatory period on fractionated reaction time were investigated. Eight subjects responded with an isometric elbow flexion to light stimuli under three experimental conditions, adjusting force output to match two target forces (10% or 40% of maximal isometric voluntary elbow flexion strength) displayed on an oscilloscope. Analysis indicates that the relationship between premotor time and force output is affected by preparatory states in the central nervous system, and the preparatory time necessary for exertion of a specific force varies with the magnitude of exerted force.

Effects of Speed and Accuracy of Exertion of Force on the Relationship between Force Output and Fractionated Reaction Time

The present study was designed to investigate the effect of speed and accuracy of force exertion on the relationship between force output and fractionated reaction time. Subjects exerted their force (10% or 40% of maximum isometric contraction) on "accurate" and "fast" tasks as rapidly as possible at the light signal. On the "fast" task, premotor time for the 40% target was lengthened in comparison with that for the 10% target, and motor time was shortened with an increase of force output. On the "accurate" task, on the other hand, premotor time was independent of magnitude of force, and no relation between motor time and force output was found. These findings show that the relationship between force output and fractionated reaction time may be affected by the effort to exert force accurately.