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1.
Abstract The purpose of this study was to compare reaction time (RT) and fractionated RT components (premotor and motor times) between normal and postcontraction conditions. Twelve participants performed 20 trials each of control and postcontraction RT conditions. For the control condition, participants executed a learned, rapid, knee-extension contraction response to an auditory stimulus. The postcontraction condition was identical to the control condition except that the participants performed a 3-s isometric contraction of the knee extensor muscles prior to an auditory stimulus. Muscle activity was recorded from the quadriceps muscle group. Results indicated that the postcontraction condition was significantly faster than the control condition for the average RT, premotor time, and motor time. It was concluded that reaction time, processing time, and muscle contraction time for a learned task could be significantly reduced following an isometric contraction. 相似文献
2.
In this study, we examined the relative control of reaction time and force in responses of the lower limb. Fourteen female participants (age 21.2 +/- 1.0 years, height 1.62 +/- 0.05 m, body mass 54.1 +/- 6.1 kg; mean +/- s) were instructed to exert their maximal isometric one-leg extension force as quickly as possible in response to an auditory stimulus presented after one of 13 foreperiod durations, ranging from 0.5 to 10.0 s. In the 'irregular condition' each foreperiod was presented in random order, while in the 'regular condition' each foreperiod was repeated consecutively. A significant interactive effect of foreperiod duration and regularity on reaction time was observed (P < 0.001 in two-way ANOVA with repeated measures). In the irregular condition the shorter foreperiod induced a longer reaction time, while in the regular condition the shorter foreperiod induced a shorter reaction time. Peak amplitude of isometric force was affected only by the regularity of foreperiod and there was a significant variation of changes in peak force across participants; nine participants were shown to significantly increase peak force for the regular condition (P < 0.001), three to decrease it (P < 0.05) and two showed no difference. These results indicate the independence of reaction time and response force control in the lower limb motor system. Variation of changes in peak force across participants may be due to the different attention to the bipolar nature of the task requirements such as maximal force and maximal speed. 相似文献
3.
Abstract It is well documented that simple reaction time (RT) varies inversely with stimulus intensity, but there is disagreement as to which stimulus modality produces the fastest simple RT. An investigation was conducted to equate two stimulus modalities, auditory (A) and electrocutaneous (EC), using varying stimulus intensities in a simple RT protocol. A second investigation was then conducted to examine neuromotor characteristics of stimulus-evoked responses using previously equated A and EC stimuli of varying intensity from the first investigation. Results showed that RT, premotor time (PMT), and motor time (MT) were all inversely related to stimulus intensity, while maximum displacement (MAXD) was directly related to stimulus intensity, and movement time was not affected by stimulus intensity. We conclude that: (a) both central and peripheral components of RT are altered by varying stimulus intensities, and (b) rapid movements are enhanced by increasing stimulus intensity. 相似文献
4.
Tatsuyuki Ohtsuki ‡ 《Journal of sports sciences》2013,31(4):373-382
In this study, we examined the relative control of reaction time and force in responses of the lower limb. Fourteen female participants (age 21.2±1.0 years, height 1.62±0.05?m, body mass 54.1±6.1?kg; mean±s) were instructed to exert their maximal isometric one-leg extension force as quickly as possible in response to an auditory stimulus presented after one of 13 foreperiod durations, ranging from 0.5 to 10.0?s. In the ‘irregular condition’ each foreperiod was presented in random order, while in the ‘regular condition’ each foreperiod was repeated consecutively. A significant interactive effect of foreperiod duration and regularity on reaction time was observed (P?<?0.001 in two-way ANOVA with repeated measures). In the irregular condition the shorter foreperiod induced a longer reaction time, while in the regular condition the shorter foreperiod induced a shorter reaction time. Peak amplitude of isometric force was affected only by the regularity of foreperiod and there was a significant variation of changes in peak force across participants; nine participants were shown to significantly increase peak force for the regular condition (P?<?0.001), three to decrease it (P?<?0.05) and two showed no difference. These results indicate the independence of reaction time and response force control in the lower limb motor system. Variation of changes in peak force across participants may be due to the different attention to the bipolar nature of the task requirements such as maximal force and maximal speed. 相似文献
5.
Tom R. Thomas Gil L. Etheridge Ben R. Londeree Wayne Shannon 《Research quarterly for exercise and sport》2013,84(4):709-714
Abstract The superiority of motor set reaction time over sensory set reaction time has been accepted since the 1880s. Recently, however, there has been work favoring the sensory set. This study attempted to reconcile the varied findings. Woodworth had suggested that set and stimulus intensity interact. To test that presumed interaction and related ideas, the study proposed to determine not only the effect of motor set and sensory set on reaction time (RT) and muscle electrical activity (MEA), but also, the relationship between motor set and sensory set RT and motor set and sensory set MEA. Twenty-four subjects were tested in sessions that included the placement of electrodes on the motor end point of the extensor digitorum muscle, set instructions, practice, and data collection. Data collection consisted of recording of RT and MEA for 96 trials, 12 recordings at each of four levels of auditory stimulus intensity for each of the two sets. An ANOVA for repeated measures produced a significant interaction between set and intensity for RT; thus the Woodworth prediction was upheld. The results seem best explained in terms of signal detection theory and the attention demands of movement. 相似文献
6.
Abstract The present study sought to determine whether individuals could be trained to attenuate the visual dominance effect by selecting a proprioceptive stimulus for attention. Using a reaction time (RT) task, subjects received either: (a) visual (V), (b) proprioceptive (P), or (c) combined V and P (VP) stimuli during the first four days. Each subject was then tested under all three stimuli conditions. Results showed that reaction time to the P cue was always faster than that to V or combined VP stimuli. The order in which subjects were tested under each stimulus modality significantly affected the results such that those subjects who received initial exposure to the V stimulus produced the slowest premotor time scores but the fastest motor time scores. These results suggest that the nature of the stimulus which initiates the volitional task can affect both the central processing requirements to initiate the response, and the qualitative manner in which the motor command is executed. 相似文献
7.
Donald Siegel 《Research quarterly for exercise and sport》2013,84(2):128-131
The purpose of this study was to determine how the manipulation of movement duration affects components of fractionated reaction time and presumably motor programming. Twelve subjects, in a simple reaction time paradigm, responded to an auditory signal by executing an elbow flexion movement in the sagittal plane through a range of motion of 100° in 150, 300, 600 and 1200 ms. Results indicated no changes in motor time but small increments in premotor and reaction time through the 600 ms condition. At 1200 ms, reaction time increased faster than premotor time, and this appeared to be predominantly a consequence of an increment in motor time. These data were interpreted to be supportive of the notion that movement duration is related to response complexity and the time required for motor programming. 相似文献
8.
BackgroundResidual torque enhancement (rTE) is the increase in torque observed during the isometric steady state following active muscle lengthening when compared with a fixed-end isometric contraction at the same muscle length and level of neuromuscular activation. In the rTE state, owing to an elevated contribution of passive force to total force production, less active force is required, and there is a subsequent reduction in activation. In vivo studies of rTE reporting an activation reduction are often performed using a dynamometer, where participants contract against a rigid restraint, resisting a torque motor. rTE has yet to be investigated during a position task, which involves the displacement of an inertial load with positional control.MethodsA total of 12 participants (6 males, 6 females; age = 22.8 ± 1.1 years, height = 174.7 ± 8.6 cm, mass = 82.1 ± 37.7 kg; mean ± SD) completed torque- and position-matching tasks at 60% maximum voluntary contraction for a fixed-end isometric contraction and an isometric contraction following active lengthening of the ankle dorsiflexors.ResultsThere were no significant differences in activation between torque- and position-matching tasks (p = 0.743), with ∼27% activation reduction following active lengthening for both task types (p < 0.001).ConclusionThese results indicate that rTE is a feature of voluntary, position-controlled contractions. These findings support and extend previous findings of isometric torque-control conditions to position-controlled contractions that represent different tasks of daily living. 相似文献
9.
Abstract Motor pool excitability, H-reflex amplitude, was studied in RT responses preceded by varied foreperiods. Rapid plantar flexion of the foot followed auditory warning signals, varied foreperiods, and visual RT stimuli. Response speed was latency of EMG onset in the soleus muscle (PMT). The H-reflex stimulus was either omitted (none), or presented at one of three intervals in the movement response period: 0 (simultaneous with RT stimulus), 100 or 200 ms following stimulus. Control H-reflexes were taken before and after RT trials. The motor pool was not differentially excited following the random foreperiods. In fact it was not elevated over control values until late into the preparatory period (200 ms) which probably reflects the direct expression of the motor command. Using the H-reflex paradigm in combination with a RT response strongly altered the PMT when the H-reflex was presented early in the preparatory period (0). Since motor pool excitability changes were not evident early in the movement preparation period, they poorly predicted PMTs. 相似文献
10.
研究目的：探讨动力性与静力性肌肉收缩时EMG各参数的变化特征及疲劳时各指标的差异，比较不同项目运动员肌肉收缩特征对EMG参数的影响及与该项目的关系。研究方法：27名受试者分为两组，第一组为赛艇运动员（组一），第二组为田径爆发性力量项目（跳跃、短跑）专选运动员（组二）。受试者以2／3Mvc做静力性持续等长收缩，动力性持续肌肉收缩则采用本人的MVC，同时记录EMG信号，分析IEMG、E／T值和MF。研究结果：持续静力性肌肉收缩时，随疲劳的发展赛艇运动员与田径运动员IEMG、E／T值均显著升高。但赛艇运动员从运动开始至80％时段一直保持平稳，此后迅速上升。静力性收缩时两组运动员随疲劳发展MF从高频向低频转移，但田径运动员频率下降速率要快于赛艇运动员。结论：赛艇运动训练促使大脑皮层动员运动单位工作更具有时间耐久性。快速、爆发式运动使疲劳时大脑皮层兴奋性下降更快，肌肉更易于疲劳。 相似文献
11.
Reaction time, fractionated reaction time (premotor and motor time), and movement time were recorded during performance of a rapid aiming movement (11 mm in amplitude) to a circular target. Independent variables were target diameter (2 or 64 mm) and reaction time condition (simple or choice). Fifty-two subjects performed 16 practice and 24 performance trials under one of four possible experimental combinations (13 subjects per combination) in a 2 × 2 design. Reaction time correlated highly with premotor time (r = .99) but not with motor time (r = .31). Choice reaction time and its premotor time component were dependent upon target diameter, but simple reaction time and its premotor time component were not. However, choice and simple motor time were not differentially affected by target diameter. As expected, movement time was longer for the small target than for the large target. Taken together, the reaction time results were interpreted as support for Klapp's (1975) hypothesis that increases in choice reaction time for rapid movements to a small target are due to increases in the time needed for programing the response. 相似文献
12.
《European Journal of Sport Science》2013,13(6):455-461
Abstract In this study, we wished to determine whether a warm-up exercise consisting of 100 submaximal concentric contractions would attenuate delayed-onset muscle soreness and decreases in muscle strength associated with eccentric exercise-induced muscle damage. Ten male students performed two bouts of an elbow flexor exercise consisting of 12 maximal eccentric contractions with a warm-up exercise for one arm (warm-up) and without warm-up for the other arm (control) in a randomized, counterbalanced order separated by 4 weeks. Muscle temperature of the biceps brachii prior to the exercise was compared between the arms, and muscle activity of the biceps brachii during the exercise was assessed by surface integral electromyogram (iEMG). Changes in visual analogue scale for muscle soreness and maximal voluntary isometric contraction strength (MVC) of the elbow flexors were assessed before, immediately after, and every 24 h for 5 days following exercise, and compared between the warm-up and control conditions by a two-way repeated-measures analysis of variance. The pre-exercise biceps brachii muscle temperature was significantly (P<0.01) higher for the warm-up (35.8±0.2°C) than the control condition (34.4±0.2°C), but no significant differences in iEMG and torque produced during exercise were evident between conditions. Changes in muscle soreness and MVC were not significantly different between conditions, although these variables showed significant (P<0.05) changes over time. It was concluded that the warm-up exercise was not effective in mitigating delayed-onset muscle soreness and loss of muscle strength following maximal eccentric exercise. 相似文献
13.
This study investigated the time needed to change a motor program that specified the elbow flexor muscles to gradually increase the isometric force production from 15% to 75% of one's maximum voluntary contraction (MVC). A double-stimulation paradigm was used with the restriction that subjects (N = 12) be at 15% of their MVC before the presentation of the first stimulus. Subjects reacted to the first stimulus (randomly presented) by gradually increasing their isometric force from 15% to 75% of their MVC and then reacted to the second stimulus by altering the force production in one of four ways: (a) increasing the force to the 75% level rapidly instead of gradually, (b) discontinuing the increase and maintaining the level of force attained, (c) discontinuing all force production, or (d) reversing the direction of force so that it is produced by the elbow extensors. The data revealed that more time was needed to increase the force rapidly than to perform any of the other three conditions. 相似文献
14.
Christopher Papic Peter Sinclair Che Fornusek Ross Sanders 《Sports biomechanics / International Society of Biomechanics in Sports》2019,18(4):378-389
Task-specific auditory training can improve sensorimotor processing times of the auditory reaction time (RT). The majority of competitive swimmers do not conduct habitual start training with the electronic horn used to commence a race. We examined the effect of four week dive training interventions on RT and block time (BT) of 10 male adolescent swimmers (age 14.0 ± 1.4 years): dive training with auditory components (speaker and electronic horn) (n = 5) and dive training without auditory components (n = 5). Auditory stimulus dive training significantly reduced swimming start RT, compared with dive training without auditory components (p < 0.01), with a group mean RT reduction of 13 ± 9 ms. Four of the five swimmers that received auditory stimulus training showed medium to large effect size reductions in RT (d = 0.74; 1.32; 1.40; 1.81). No significant changes to swimmers’ BTs were evident in either dive training intervention. The adolescent swimmers’ results were compared against six male elite swimmers (age 19.8 ± 1.0 years). The elite swimmers had significantly shorter BTs (p < 0.05) but no significant difference in RTs. Auditory stimulus dive training should be explored further as a mechanism for improving swimming start performance in elite swimmers who have pre-established optimal BTs. 相似文献
15.
Robert W. Christina James H. Cauraugh Aaron Shire 《Research quarterly for exercise and sport》2013,84(4):338-343
Abstract This study investigated the time needed to change a motor program that specified the elbow flexor muscles to gradually increase the isometric force production from 15% to 75% of one's maximum voluntary contraction (MVC). A double-stimulation paradigm was used with the restriction that subjects (N = 12) be at 15% of their MVC before the presentation of the first stimulus. Subjects reacted to the first stimulus (randomly presented) by gradually increasing their isometric force from 15% to 75% of their MVC and then reacted to the second stimulus by altering the force production in one of four ways: (a) increasing the force to the 75% level rapidly instead of gradually, (b) discontinuing the increase and maintaining the level of force attained, (c) discontinuing all force production, or (d) reversing the direction of force so that it is produced by the elbow extensors. The data revealed that more time was needed to increase the force rapidly than to perform any of the other three conditions. 相似文献
16.
《运动与健康科学(英文)》2023,12(4):523-533
BackgroundFemales are typically less fatigable than males during sustained isometric contractions at lower isometric contraction intensities. This sex difference in fatigability becomes more variable during higher intensity isometric and dynamic contractions. While less fatiguing than isometric or concentric contractions, eccentric contractions induce greater and longer lasting impairments in force production. However, it is not clear how muscle weakness influences fatigability in males and females during sustained isometric contractions.MethodsWe investigated the effects of eccentric exercise-induced muscle weakness on time to task failure (TTF) during a sustained submaximal isometric contraction in young (18–30 years) healthy males (n = 9) and females (n = 10). Participants performed a sustained isometric contraction of the dorsiflexors at 35° plantar flexion by matching a 30% maximal voluntary contraction (MVC) torque target until task failure (i.e., falling below 5% of their target torque for ≥2 s). The same sustained isometric contraction was repeated 30 min after 150 maximal eccentric contractions. Agonist and antagonist activation were assessed using surface electromyography over the tibialis anterior and soleus muscles, respectively.ResultsMales were ∼41% stronger than females. Following eccentric exercise both males and females experienced an ∼20% decline in maximal voluntary contraction torque. TTF was ∼34% longer in females than males prior to eccentric exercise-induced muscle weakness. However, following eccentric exercise-induced muscle weakness, this sex-related difference was abolished, with both groups having an ∼45% shorter TTF. Notably, there was ∼100% greater antagonist activation in the female group during the sustained isometric contraction following exercise-induced weakness as compared to the males.ConclusionThis increase in antagonist activation disadvantaged females by decreasing their TTF, resulting in a blunting of their typical fatigability advantage over males. 相似文献
17.
L. Verburgh E. J. A. Scherder P. A. M. van Lange J. Oosterlaan 《Journal of sports sciences》2016,34(18):1782-1790
In sports, fast and accurate execution of movements is required. It has been shown that implicitly learned movements might be less vulnerable than explicitly learned movements to stressful and fast changing circumstances that exist at the elite sports level. The present study provides insight in explicit and implicit motor learning in youth soccer players with different expertise levels. Twenty-seven youth elite soccer players and 25 non-elite soccer players (aged 10–12) performed a serial reaction time task (SRTT). In the SRTT, one of the sequences must be learned explicitly, the other was implicitly learned. No main effect of group was found for implicit and explicit learning on mean reaction time (MRT) and accuracy. However, for MRT, an interaction was found between learning condition, learning phase and group. Analyses showed no group effects for the explicit learning condition, but youth elite soccer players showed better learning in the implicit learning condition. In particular, during implicit motor learning youth elite soccer showed faster MRTs in the early learning phase and earlier reached asymptote performance in terms of MRT. Present findings may be important for sports because children with superior implicit learning abilities in early learning phases may be able to learn more (durable) motor skills in a shorter time period as compared to other children. 相似文献
18.
超声波技术作为一种对人体肌肉特征变化的测试手段正被广泛地运用.采用文献综述法,对超声波技术应用中的常用参数及运动条件下的肌肉、腱组织的形态特征进行归纳和总结.在分析从等长收缩到复杂的SSC收缩中肌腱复合体变化特征的基础上,认为:如果肌纤维决定收缩力、腱组织决定速度储备,肌腱复合体的性能则决定对外输出功的大小. 相似文献
19.
Walter Kroll Priscilla M. Clarkson Gary Kamen Jean Lambert 《Research quarterly for exercise and sport》2013,84(2):323-333
Abstract Muscle fiber type composition in the vastus lateralis and knee extension isometric strength fatigue patterns were assessed in eight endurance-trained and eight power-trained males. Two different 25-trial isometric contraction exercise regimens were administered: a 10-second contraction, 5-second intertrial rest condition designed to induce a fast rate of fatigue and a 10-second contraction, 20-second intertrial rest condition designed to induce a slower rate of fatigue. The power group fatigued almost four times faster than the endurance group in the 10:5 exercise condition. In the 10:20 exercise condition, the endurance group showed no fatigue pattern while the power group had a significant strength decrement of 32%. In both exercise conditions, the power group exhibited more complex fatigue patterns in terms of statistically significant trend components. Maximum isometric strength correlated positively with slow twitch (ST) percent number in power (r = .80) and endurance (r = .48) groups, but negatively with linear trend coefficients in endurance (r = -.62) and power (r = -.80) groups. Maximum isometric strength also correlated higher with fatigue curve trend coefficients than did muscle fiber type composition. Thus, a faster rate of fatigue was associated with higher maximum isometric strength and with higher ST percent number and area. Since maximum isometric strength correlated with body weight (r = .86 for groups combined), both maximum isometric strength and muscle mass appear to be more important determinants of knee extension isometric strength fatigue patterns than muscle fiber type composition. 相似文献
20.
Eloisa Limonta Emiliano Cè Massimiliano Gobbo Arsenio Veicsteinas Claudio Orizio 《Journal of sports sciences》2016,34(2):133-142
The aim of the study was to evaluate, by an electromyographic (EMG) and mechanomyographic (MMG) combined approach, whether years of specific climbing activity induced neuromuscular changes towards performances related to a functional prevalence of fast resistant or fast fatigable motor units. For this purpose, after the maximum voluntary contraction (MVC) assessment, 11 elite climbers and 10 controls performed an exhaustive handgrip isometric effort at 80% MVC. Force, EMG and MMG signals were recorded from the finger flexor muscles during contraction. Time and frequency domain analysis of EMG and MMG signals was performed. In climbers: (i) MVC was higher (762 ± 34 vs 512 ± 57 N; effect size: 1.64; confidence interval: 0.65–2.63; P < 0.05); (ii) endurance time at 80% MVC was 43% longer (34.2 ± 3.7 vs 22.3 ± 1.5 s; effect size: 1.21; confidence interval: 0.28–2.14; P < 0.05); (iii) force accuracy and stability were greater during contraction (P < 0.05); (iv) EMG and MMG parameters were higher throughout the entire isometric effort (P < 0.05). Collectively, force, EMG and MMG combined analysis revealed that several years of specific climbing activity addressed the motor control system to adopt muscle activation strategies based on the functional prevalence of fast resistant motor units. 相似文献