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Kendall, BJ, Siekirk, NJ, and Lai, Q. Effects of acute high-intensity interval training on information processing speed. J Strength Cond Res XX(X): 000-000, 2021-This study investigated the effects of acute exercise on reaction time (RT), premotor time (i.e., central processing), and motor time (i.e., peripheral processing) using surface electromyography to fractionate RT. Fifty-eight young adults (27 men, 31 women) between the age of 18 and 40 years participated in 2 testing sessions. During visit one, subjects performed a simple RT task under regular (i.e., consistent timing) and irregular (i.e., variable timing) foreperiods. Subjects were then randomized to either an aerobic-only high-intensity interval training (HIIT) group (HIIT-A), an aerobic/resistance HIIT group (HIIT-AR), or a resting control group (CG). Both exercise groups performed a 20-minute, digital video disc-delivered HIIT exercise protocol. After exercise or rest, when controlling for cardiovascular fitness, no statistical differences were observed for the regular foreperiod conditions (p > 0.05). For the irregular foreperiod conditions, the HIIT-A group (M = 219.8, SE = 6.5) and the HIIT-AR group (M = 218.2, SE = 5.8) had significantly faster mean RTs than the CG (M = 248.1, SE = 8.1). In addition, the HIIT-A (M = 172.1, SE = 4.6) and HIIT-AR exercise groups (M = 171.3, SE = 4.8) had significantly faster mean PMTs than the CG (M = 189.7, SE = 5.7). These findings suggest that tasks dependent on central processing may benefit from an acute bout of exercise.

La metodología Flipped Learning (FL) está emergiendo como un enfoque pedagógico innovador que enriquece el proceso de enseñanza-aprendizaje mediante el uso de las TIC. Este estudio pretende evaluar los efectos de su aplicación práctica en las clases de EF de ESO. Para ello, se desarrolló la misma Unidad didáctica sobre Pelota Valenciana en 7 grupos de 1º ESO, aplicando dos metodologías diferentes: FL (FLIP) o tradicional (TRAD). Se evaluaron los niveles de aprendizaje, motivación y tiempo de práctica motriz pre y post intervención. Los resultados no mostraron diferencias significativas entre ambas metodologías, con respecto a la motivación y al nivel de aprendizaje (p = 0,633). Sin embargo, los tiempos de práctica motriz de FLIP fueron mayores en comparación con TRAD (p = 0,034). En conclusión, obteniendo similares niveles de aprendizaje y motivación, el enfoque FL logró un mayor tiempo de práctica motriz en los estudiantes durante las clases de EF.

Introduction This study aimed to investigate the effects of fascial manipulation (FM) on muscle force and electrical activity. Methods Sixty healthy adult participants were randomly assigned to the FM intervention group (FM group; n=20), static stretching intervention group (SS group; n=20), and control group (C group; n=20). The FM group underwent FM for the right brachial fascia (antecubitus) for 210 s. The SS group underwent static stretching of the right biceps brachii for 210 s. The C group was supine for 210 s. Participants were asked to flex the right elbow joint as quickly as possible after a light signal appeared during three sessions (before, immediately after, and 1 week after the intervention). During each session, the muscle activity of the right biceps brachii and bending force of the right elbow joint were measured. We calculated the reaction time (RT), pre-motor time (PMT), motor time (MT), time to peak force (TPF), and time to peak activity (TPA) from these measurements. Results The RT, MT, TPA, and TPF of the FM group were significantly shorter immediately after or 1 week after the intervention compared with those before the intervention. The RT, MT, TPA, and TPF of the FM group were significantly shorter than those of the SS group or C group immediately after or 1 week after the intervention. Conclusion FM improved RT, MT, TPA, and TPA, and the effects lasted for 1 week. Both mechanical and neurological factors may contribute to improvements in motor performance after FM.

Recently, there have been several studies that have examined the acute effects of aerobic exercise on cognitive function. Importantly, one precise indicator of cognitive function is response time (RT), which has two main components; premotor time (PMT) and motor time (MT). PMT is the time for perception, decision making and response preparation, while MT is executing the response. Using fractionated response time (FRT) instead of RT provides a more precise estimate of the location of the effect of aerobic exercise on cognitive or motor components of the response. There is emerging evidence that shows an acute bout of exercise may improve FRT. Therefore, the purpose of this systematic review and meta-analysis was to explore the acute effect of aerobic exercise on FRT by considering the effects of various cognitive function tests. Fourteen studies were included investigating FRT during and/or after aerobic exercise. The results indicated that during exercise, PMT increased in simple reaction time and decreased in flanker task; MT decreased in choice reaction time; interestingly, RT decreased when it was assessed by choice reaction time and flanker task, almost similar to PMT and MT. After exercise, PMT decreased specifically in flanker and go/no-go tasks. However, MT and RT did not change significantly. In conclusion, as changes in RT are affected by both PMT and MT, FRT provides a more precise estimate of the locus of the effects of aerobic exercise on response time.

The study hypothesis held that in subjects with Parkinson’s disease (PD), the reaction time (RT) tests of the higher cognition demand would have more readily improved under the program of analog microgravity (μG) modeled with “dry” immersion (DI). To test this hypothesis, 10 subjects with PD have passed through a program of seven DI sessions (each 45 min long) within 25–30 days, with overall μG dose 5 1/4 h. Five patients were enrolled as controls, without DI (noDI group). Simple RT (SRT), disjunctive RT (DRT), and choice RT (CRT) were assessed in four study points: before the DI program (preDI), 1 day after the DI program (postDI), 2 weeks after the DI program (DI2w), and 2 months after the DI program (DI2m). The motor time (MT) was assessed with the tapping test (TT). Additionally, signal detection time (SDT) and central processing time (CPT) were extracted from the data. Before the program of DI, the RT tests are in accordance with their cognition load: SRT (284 ± 37 ms), DRT (338 ± 38 ms), and CRT (540 ± 156 ms). In accordance with the hypothesis, CRT and DRT have improved under DI by, respectively, 20 and 8% at the study point “DI2w,” whereas SRT, SDT, and MT did not change (p > 0.05). Thus, the program of DI provoked RT improvement specifically in the cognitively loaded tasks, in a “dose of cognition-reaction” manner. The accuracy of reaction has changed in none of the RT tests. The neurophysiologic, hormonal/neuroendocrine, behavioral, neural plasticity, and acclimation mechanisms may have contributed to such a result.

The aim of the study was to assess selected cognitive abilities depending on age, anthropometric parametres, physical fitness and technical skills in the group of young players training football. The study covered a group of 258 young players practicing football (age: 12.1± 2.03), who were divided into 5 age categories (8–9 years old, 10–11 years old, 12–13 years old, 14–15 years old, 16–17 years old). Selected cognitive abilities include: simple reaction time (SIRT), complex reaction time (CHORT), hand-eye coordination (HECOR) and spatial orientation (SPANT). Studies were performed using Test2Drive computer tests. In addition, the level of physical fitness was measured using: The standing long jump, 30 m sprint, 20 m shuttle run test (without and with the ball) and slalom (without and with the ball). The analysis showed a statistically significant relationship between age and cognitive abilities. There was also a statistically significant correlation between fitness tests and reaction time in individual cognitive tests. There were no statistically significant relationships between technical skills and cognitive abilities. The study confirms that age and physical fitness affect the level of cognitive abilities.

This study aimed to apply electromyographic techniques and distributional analyses to test whether an increase in the strength of stimulus-response mapping could explain the mechanisms underlying the joint Simon effect. Within a single protocol, participants performed a Simon task and a Go/NoGo task in isolation, and a joint Go/NoGo task with a co-actor (joint Simon task). Results showed that joint-action impairs cognitive control and shortened reaction time by impacting both pre-motor time and motor time. Joint-action induced a larger facilitation on pre-motor time of ipsilateral than contralateral associations. This potentiation of the spatial correspondence effect plausibly explains the larger Simon-like effect usually observed in the joint Go/NoGo task compared to that observed in the isolated Go/NoGo task. The propensity of making incorrect activations and their concentration among fast responses also increased when working co-actively. Together, these findings indicate that joint-action increases the strength of automatic response capture induced by the stimulus location, promotes the delivery of the stronger association in the behavioral repertoire of the individual, and reduces cognitive control.; This study aimed to apply electromyographic techniques and distributional analyses to test whether an increase in the strength of stimulus-response mapping could explain the mechanisms underlying the joint Simon effect. Within a single protocol, participants performed a Simon task and a Go/NoGo task in isolation, and a joint Go/NoGo task with a co-actor (joint Simon task). Results showed that joint-action impairs cognitive control and shortened reaction time by impacting both pre-motor time and motor time. Joint-action induced a larger facilitation on pre-motor time of ipsilateral than contralateral associations. This potentiation of the spatial correspondence effect plausibly explains the larger Simon-like effect usually observed in the joint Go/NoGo task compared to that observed in the isolated Go/NoGo task. The propensity of making incorrect activations and their concentration among fast responses also increased when working co-actively. Together, these findings indicate that joint-action increases the strength of automatic response capture induced by the stimulus location, promotes the delivery of the stronger association in the behavioral repertoire of the individual, and reduces cognitive control.

BACKGROUND The physical activity and playing actions performed during a soccer match vary according to player position. The aim of the present study was to analyze the recovery kinetics of cognitive performance, physical performance and subjective ratings after a competitive soccer match. METHODS Eight goalkeepers and eight outfield players played in the match with data collected before, 45 min, 24 h and 48 h after the match. Subjective ratings, Vienna Reaction Test (reaction time, motor time), Vienna Determination Test (number of stimuli, number of correct responses), squat jump, countermovement jump and 6-s sprint were analyzed. RESULTS No significant interaction between position and time was found for Vienna Reaction Test and Vienna Determination Test performance. No significant interaction between position and time was found for squat jump and countermovement jump but squat jump and countermovement jump significantly decreased (P

[Purpose] The aim of this study was to examine the immediate effects of muscle strength training and neuromuscular joint facilitation distal resistance training on wrist joints by using electromechanical reaction time. [Subjects and Methods] The subjects were 12 healthy young people (24.2 ± 3.1 years, 169.7 ± 6.5 cm, 65.3 ± 12.6 kg). Two kinds of isotonic contraction techniques were applied on the wrist joint: the wrist joint extension muscle strength training and the wrist joint extension pattern of neuromuscular joint facilitation. The electromechanical reaction time, premotor time, and motor time of the left upper limb were measured before and after each intervention session of muscle strength training and neuromuscular joint facilitation. [Results] The neuromuscular joint facilitation group showed significant shortening of the electromechanical reaction time and motor time after the intervention. [Conclusion] These results suggest that the electromechanical reaction time and motor time of the wrist joint can be improved by neuromuscular joint facilitation together with proximal resistance training, which can be used as a new form of exercise for improving the functions of subdominant hand wrist joints.

International audience; We designed a two-alternative forced choice experiment in which the by-trial reaction times could be fraction-ated into pre-motor (PMT) and motor times (MT), based on the onset of muscular activity from the electromyo-graphic (EMG) recordings (Figure 2c). We then compared this empirical decomposition to the decomposition performed by the Drift Diffusion Model (DDM, Ratcliff, 1978). Using these two decompositions, we show that the non-decision time parameter of the DDM is highly correlated with the Motor Time that was recorded when the participants stressed Accuracy over Speed. Furthermore, we show that fitting the by-trial Pre-Motor Time with the DDM mainly modulated the non-decision time parameters. The relative contribution of decision time and motor time components in the overall Reaction Time (based on speed versus accuracy instructions) was observed. Correlation analyses between speed instructions on empirical data suggest that their could be a change in the architecture of cognitive processes rather than a quantitative change between Speed-Accuracy tradeoff (SAT) levels.

Both in real life and experimental settings, increasing response speed typically leads to more error-prone actions. Processes underlying such a "speed-accuracy trade-off" (SAT) are usually assumed to be purely decisional: cautiousness would be determined only by the amount of sensory evidence required to select a response. The present data challenges this largely accepted view, by directly showing that motor processes are speeded up under time pressure. In a choice reaction time task where emphasis was put either on response speed or accuracy, motor processes were investigated through the analysis of muscular activity related to response execution. When response speed was emphasized, the time between electromyographic onset and behavioral response (motor time) was also speeded up (contributing to more than 20 % of the total effect on global reaction time). This speeded execution (likely due to a more efficient motor command) may also explain why participants are less able to interrupt incorrect response execution once started (Burle et al., Psychonomic BulletinReview, 21(4), 1003-1010, 2014), leading to more overt errors. Pointing to a speed-accuracy exchange within motor processes themselves, the present results call for a re-evaluation of widely accepted assumptions about SAT, and more generally, decision-making processes. They are discussed in the context of recent extensions of the drift diffusion model framework, questioning the strict separation between decisional and motor processes.

International audience; Arousal anxiety has a great impact on reaction time, physiological parameters and motor performance. Numerous studies have focused on the influence of anxiety on muscular activity during simple non ecologic task. We investigate the impact of a moderate state-anxiety (arousal stressor) on the specific component of a complex multi-joint ecologic movement during a reaction time task of auditory stimulus-response. Our objective is to know if central and peripheral voluntary motor processes were modulated in the same way by an arousal stressor. Eighteen women volunteers performed simple reaction time tasks of auditory stimulus-response. Video-recorded Stroop test with interferences was used to induced moderate state-anxiety. Electromyographic activity of the wrist extensor was recorded in order to analyse the two components of the reaction time: the premotor and motor time. In anxiogenic condition, an acceleration and an increase of muscular activity of the reaction time was obtained. This increase was due to a stronger muscle activity during the premotor time in the anxiogenic condition. Arousal anxiety has a different impact on central and peripheral voluntary motor processes. The modifications observed could be related to an increase in arousal related to a higher anxiety in order to prepare the body to act.

The purposes were twofold: (a) to ascertain the inter-session reliability of hamstrings total reaction time,\ud pre-motor time and motor time; and (b) to examine sex-related differences in the hamstrings reaction\ud times profile. Twenty-four men and 24 women completed the study. Biceps femoris and semitendinosus\ud total reaction time, pre-motor time and motor time measured during eccentric isokinetic contractions\ud were recorded on three different occasions. Inter-session reliability was examined through typical\ud percentage error (CVTE), percentage change in the mean (CM) and intraclass correlations (ICC). For both\ud biceps femoris and semitendinosus, total reaction time, pre-motor time and motor time measures demonstrated\ud moderate inter-session reliability (CVTE < 10%; CM < 3%; ICC > 0.7). The results also indicated\ud that, although not statistically significant, women reported consistently longer hamstrings total reaction\ud time (23.5 ms), pre-motor time (12.7 ms) and motor time (7.5 ms) values than men. Therefore, an\ud observed change larger than 5%, 9% and 8% for total reaction time, pre-motor time and motor time respectively\ud from baseline scores after performing a training program would indicate that a real change was\ud likely. Furthermore, while not statistically significant, sex differences were noted in the hamstrings reaction\ud time profile which may play a role in the greater incidence of ACL injuries in women.

Use of different effectors in two consecutive actions could generate an attentional shift between the effectors with shorter latencies in the second action of reaching. 18 participants (10 men; M age = 21.3 yr.) participated in an experiment with two main variables: (1) effector switching with two levels (Switching and No Switching), where the participants use or do not use a different motor effector for each action; (2) lifting muscles, i.e., the muscles involved in the first phase of the reaching, with two levels (finger-lifting muscle and palm-lifting muscle). Premotor time, Motor time, Reaction time, Movement time, and Total time were measured. For Premotor, Movement, and Total times, faster responses were observed when there was no switching of the effector. This delay could be due to an attentional shift between motor effectors and its relations with motor processes. Possible applications include the ergonomic design of device controls, considering that the use of the same effector is beneficial when fast reaction times are sought.

The main purposes of this study were to (a) investigate acute effects of static and dynamic lower limb stretching routines on total response time, pre-motor time and motor time of the medial and lateral hamstrings during maximal eccentric isokinetic knee flexion; and (b) determine whether static and dynamic routines elicit similar responses. A total of 38 active adults completed the following intervention protocols in a randomised order on separate days: (a) non-stretching (control condition), (b) static stretching and (c) dynamic stretching. After the stretching or control intervention, total response time, pre-motor time and motor time of the medial and lateral hamstrings were assessed during eccentric knee flexion movements with participants prone. Measures were compared via a mixed-design factorial ANOVA. There were no main effects for total response time, pre-motor time and motor time. The results suggest that dynamic and static stretching has no influence on hamstrings response times (total response time, pre-motor time and motor time) and hence neither form of stretching reduces this primary risk factor for anterior cruciate ligament injury.

The cancellation task is a paper-and-pencil test commonly used to assess attention or planning. This study investigated whether the decision time performance on the task was influenced by the number of targets and distractors. This study reduced the demand of planning and used an index of the decision time, an estimate of the time taken to decide whether to mark a stimulus. Forty healthy adults ( M age = 21.3 yr., SD = 1.5) performed five cancellation tasks. Four tasks were conducted with instructions to mark a detected target. The target-to-distractor ratio varied from 35/15,40/10,45/5, and 50/0, and one task with instructions to mark all stimuli (50/0), to measure the motor time to mark targets. One-way analysis of variance indicated statistically significant differences between conditions. There was a linear relationship between decision time and target-to-distractor ratio; the decision time increased as the proportion of distractors increased. The results suggested the decision time reflects the frequency of switches between responses to targets and distractors or attention modulation of processing to targets and distractors.

Aim Reaction times of the hip abductor were reported to be longer in elderly women than in elderly men, and this was suggested to be related to mediolateral balance performance. The aim of the present study was to investigate the effects of age and gender on the reaction performance of ankle muscles, which have predominant roles in anterioposterior balance control. Methods A total of 40 elderly subjects and 40 young subjects (even number of men and women) carried out a series of isometric plantarflexions and dorsiflexions, as forcefully and quickly as possible, in response to auditory stimulus. Surface electromyogram at the dorsiflexor and plantarflexor were recorded, together with foot plantar force. Premotor time, motor time and total reaction time derived from the experimental data were compared between age groups and genders by two-way anova. Results Both dorsiflexor and plantarflexor showed similar reaction performance. Premotor time increased with age with no gender difference. Motor time increased with age in women and not in men, resulting in longer motor time in elderly women than in elderly men. Total reaction time was dominated by premotor time, so that it was longer in the elderly with no gender difference. Conclusion Although age-related elongation of motor time was greater in women, total reaction time was not different between the genders. This may be related to no gender difference in anterioposterior balance performance. Geriatr Gerontol Int 2014; 14: 94–99.

Introduction. The issue of asymmetry is becoming more and more widespread, causing considerable difficulties for sportspersons. The aim of this study was to assess dynamic asymmetry of complex reaction time in female épée fencers from different sports classes. Material and methods. Study participants comprised 45 female fencers divided into 3 groups. The RT-S5 test of the Vienna Test System was used to record reaction time and motor time in response to visual and audiovisual stimuli. Conclusions. The study found differences in complex reaction time between fencers of different sports classes. Champion-class fencers showed a very high dynamic asymmetry. Considerable differences in complex reaction time were found depending on the type of stimulus involved.

Made available in DSpace on 2018-11-26T16:33:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-06-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação para o Desenvolvimento da UNESP (FUNDUNESP) Backgrounds Low strength and neuromuscular activation of the lower limbs have been associated with falls making it an important predictor of functional status in the elderly. Aim To compare the rate of neuromuscular activation, rate of torque development, peak torque and reaction time between young and elderly fallers and non-fallers for hip flexion and extension. Methods We evaluated 44 elderly people who were divided into two groups: elderly fallers (n = 20) and elderly non-fallers (n = 24); and 18 young people. The subjects performed three isometric hip flexion and extension contractions. Electromyography data were collected for the rectus femoris, gluteus maximus and biceps femoris muscles. Results The elderly had 49 % lower peak torque and 68 % lower rate of torque development for hip extension, 28 % lower rate of neuromuscular activation for gluteus maximus and 38 % lower rate of neuromuscular activation for biceps femoris than the young (p < 0.05). Furthermore, the elderly had 42 % lower peak torque and 62 % lower rate of torque development for hip flexion and 48 % lower rate of neuromuscular for rectus femoris than the young (p < 0.05). The elderly fallers showed consistent trend toward a lower rate of torque development than elderly non-fallers for hip extension at 50 ms (29 %, p = 0.298, d = 0.76) and 100 ms (26 %, p = 0.452, d = 0.68). The motor time was 30 % slower for gluteus maximus, 42 % slower for rectus femoris and 50 % slower for biceps femoris in the elderly than in the young. Discussion Impaired capacity of the elderly, especially fallers, may be explained by neural and morphological aspects of the muscles. Conclusion The process of senescence affects the muscle function of the hip flexion and extension, and falls may be related to lower rate of torque development and slower motor time of biceps femoris. Sao Paulo State Univ, Dept Phys Educ, Sao Paulo, Brazil Univ New Hampshire, Dept Kinesiol, Durham, NH 03824 USA Sao Paulo State Univ, Dept Phys Therapy & Occupat Therapy, Sao Paulo, Brazil Univ Fed Uberlandia, Dept Phys Therapy, Av Engenheiro Dinz 1178,CP 593, BR-38400 Uberlandia, MG, Brazil Univ Sao Paulo, Ribeirao Preto Med Sch, BR-14049 Ribeirao Preto, Brazil Univ Estadual Paulista, Dept Fisioterapia & Terapia Ocupac, Ave Hygino Muzzi Filho,737 Mirante, BR-17525000 Marilia, SP, Brazil Sao Paulo State Univ, Dept Phys Educ, Sao Paulo, Brazil Sao Paulo State Univ, Dept Phys Therapy & Occupat Therapy, Sao Paulo, Brazil Univ Estadual Paulista, Dept Fisioterapia & Terapia Ocupac, Ave Hygino Muzzi Filho,737 Mirante, BR-17525000 Marilia, SP, Brazil

Strenuous exercise may have the detrimental effects on visual perception. However, it is unclear whether visual resolution is related to the detrimental effects on visual perception. The purpose of this study was to examine whether the effects of strenuous exercise on visual perception are dependent on visual resolution. Given that visual resolution decreases in the periphery of the visual field, we hypothesized that if visual resolution plays a role in the detrimental effects on visual perception, the detrimental effects may be exaggerated toward the periphery of the visual field. Simple visual reaction time was measured at rest and during cycling at 40% and 75% peak oxygen uptakes (VO(2)). Visual stimuli were randomly presented at 2°, 10°, 30°, and 50° to either the right or left of the midpoint between the eyes with equal probability. RT was fractionated into premotor and motor components (i.e. premotor time and motor time) based on electromyographic recording. The premotor time during exercise at 40% peak VO(2) was not different from that at rest. In contrast, the premotor time during exercise at 75% peak VO(2) was significantly longer than that at rest (p=0.018). The increase in the premotor time was observed irrespective of eccentricity, and the detrimental effects were not exaggerated toward the periphery of the visual field. The motor time was not affected by exercise. The current findings suggest that the detrimental effects of strenuous exercise on visual perception are independent of visual resolution.

The purpose of this study was to investigate whether neuromuscular adaptations at the site of injury or neural adaptation remote to the injury are affected in individuals with chronic ankle instability (CAI). Electromyography data were collected from the peroneus longus (PL) and tibialis anterior during an ankle joint reaction time task in 12 participants with unilateral CAI and 12 healthy control participants. Following an auditory cue, time to onset of muscle activity (pre-motor time) and time from onset of muscle activity to movement (motor time) were measured during rapid ankle eversion and dorsiflexion. Reaction time for ankle eversion on the affected side was significantly slower in the CAI group than the control group, due to significantly slower motor time for the PL. Changes in motor time for the affected PL in participants with CAI may be attributed to a combination of factors associated with local tissue changes.

In a previous article, (Ries, Legou, Burle, Alario, & Malfait, 2012), we reported that articulatory processes contribute to the well-established finding that response latencies are longer for picture naming than for word reading. We based this conclusion on the observation that picture naming, as compared with word reading, lengthened not only the interval between stimulus onset and the initiation of lip muscle activation (premotor time), but also the interval between lip muscle activation and vocal response onset (motor time). However, on the basis of our subsequent work in this area, we believe that our original definition of premotor time (and, consequently, of motor time) was suboptimal. On a sizable number of trials, this led to the detection of lip muscle activation (as inferred from surface EMG) that was apparently unrelated to the articulation of the vocal response. Therefore, we believe it is preferable to operationalize premotor time as the interval between stimulus onset and the muscle activation that occurred closest in time to vocal response onset. After reestimating premotor times according to this new definition, we no longer found an effect of our task contrast on the motor time interval. The present article explains the caveats regarding our previous analysis.

The purpose of the study was to identify both demographic and neuromuscular traits that characterize successful or unsuccessful adaptation to resistance training in older women. Twelve, older women underwent electrically evoked muscle twitches for the knee extensors; and performed maximal, voluntary, isometric knee extensions, followed by eight weeks of resistance training. Prior to training nonresponders had 67% higher twitch peak torque than responders (0.29 ± 0.05 vs. 0.18 ± 0.06 Nm·kg -1 respectively), 64% higher twitch rate of torque development (RTD) (3.96 ± 0.47 vs. 2.42 ± 0.62 Nm·s -1 ·kg -1 ), 51 % higher voluntary peak torque (1.86 ± 0.40 vs. 1.23 ± 0.33 Nm·kg -1 ), 101 % greater RTD (9.43 ± 1.52 vs. 4.70 ± 2.40 Nm·s -1 ·kg -1 ), 86% greater impulse (0.13 ± 0.01 vs. 0.07 ± 0.03 Nm·s·kg -1 ) and 27% faster motor time (80 ± 13 vs. 109 ± 34 ms), (all P < 0.05). Following training, responders showed an 11 % increase in twitch peak torque over baseline (0.18 ± 0.06 to 0.20 ± 0.05 Nm·kg -1 ), 15% increase in voluntary peak torque (1.23 ± 0.33 to 1.41 ± 0.36 Nm·kg -1 ), 47% increase in RTD (4.70 ± 2.40 to 6.93 ± 2.02 Nm·s -1 ·kg -1 ), 43% increase in impulse (0.07 ± 0.03 to 0. 10 ± 0.04 Nm·s·kg- 1 ), and 26% increase in rate of EMG rise (886 ± 214 to 1116 ± 102% pEMG·s -1 ) (all P < 0.05). Initially higher muscle mass and contractility, coupled with greater neural drive, likely explains why older women with good muscle performance seem to have a lower capacity for improvement than women with low initial levels of performance.