PeerJ Preprints: Kinesiologyhttps://peerj.com/preprints/index.atom?journal=peerj&subject=5230Kinesiology articles published in PeerJ PreprintsThe effects of single versus multiple training sessions on the motor learning of two Krav Maga strike techniques, in womenhttps://peerj.com/preprints/279842019-09-252019-09-25Vincenzo E. Di BaccoMehran TaherzadehOlivier BirotWilliam H. Gage
Background. Experts of the Krav Maga (KM) self-defense system propose that KM techniques are based on simple body movements which are suggested to be learned rapidly and retained. This study investigated the acquisition, retention, and further improvement with additional training of two KM strike techniques among novice female practitioners: straight punch and defensive kick. Methods. Sixteen healthy females (age: 23 ± 3.7 years) without any previous martial arts/self-defense experience volunteered to participate. All participants received an initial 30-minute instruction session (AQ), taught by a certified KM instructor, where each technique was deconstructed into three checkpoints (defined as a component of the entire movement) for learning. Participants were divided into two groups, one of which received additional training. Several kinematic and kinetic measures were recorded at four timepoints: immediately before AQ, immediately after AQ, five days after AQ, and twelve days after AQ. Results. Results suggest that both techniques were learned rapidly, as checkpoint performance was significantly improved after AQ. Kick velocity and impact force also increased significantly after AQ, however, these measures did not change after AQ for the punch technique. Additional training did not improve either punch or kick performance beyond that learned during AQ. Conclusion. The findings from this study suggest that a single training session may be sufficient to learn and retain KM strike techniques relatively permanently; and the acquisition of the kick technique may lead to concomitant improvements in kick velocity and impact force.
Background. Experts of the Krav Maga (KM) self-defense system propose that KM techniques are based on simple body movements which are suggested to be learned rapidly and retained. This study investigated the acquisition, retention, and further improvement with additional training of two KM strike techniques among novice female practitioners: straight punch and defensive kick. Methods. Sixteen healthy females (age: 23 ± 3.7 years) without any previous martial arts/self-defense experience volunteered to participate. All participants received an initial 30-minute instruction session (AQ), taught by a certified KM instructor, where each technique was deconstructed into three checkpoints (defined as a component of the entire movement) for learning. Participants were divided into two groups, one of which received additional training. Several kinematic and kinetic measures were recorded at four timepoints: immediately before AQ, immediately after AQ, five days after AQ, and twelve days after AQ. Results. Results suggest that both techniques were learned rapidly, as checkpoint performance was significantly improved after AQ. Kick velocity and impact force also increased significantly after AQ, however, these measures did not change after AQ for the punch technique. Additional training did not improve either punch or kick performance beyond that learned during AQ. Conclusion. The findings from this study suggest that a single training session may be sufficient to learn and retain KM strike techniques relatively permanently; and the acquisition of the kick technique may lead to concomitant improvements in kick velocity and impact force.The effect of external lateral stabilization on the use of foot placement to control mediolateral stability in walking and runninghttps://peerj.com/preprints/272442019-09-202019-09-20Mohammadreza MahakiSjoerd M BruijnJaap H. van Dieën
It is still unclear how humans control mediolateral (ML) stability in walking and even more so for running. Here, foot placement strategy as a main mechanism to control ML stability was compared between walking and running. Moreover, to verify the role of foot placement as a means to control ML stability in both modes of locomotion, this study investigated the effect of external lateral stabilization on foot placement control. Ten young adults participated in this study. Kinematic data of the trunk (T6) and feet were recorded during walking and running on a treadmill in normal and stabilized conditions. Correlation between ML trunk CoM state and subsequent ML foot placement, step width, and step width variability were assessed. Paired t-tests (either SPM1d or normal) were used to compare aforementioned parameters between normal walking and running. Two-way repeated measures ANOVAs (either SPM1d or normal) were used to test for effects of walking vs. running and of normal vs. stabilized condition. We found a stronger correlation between ML trunk CoM state and ML foot placement and significantly higher step width and step width variability in walking than in running. The correlation between ML trunk CoM state and ML foot placement, step width, and step width variability were significantly decreased by external lateral stabilization in walking and running, and this reduction was stronger in walking than in running. We conclude that ML foot placement is coordinated to ML trunk CoM state to stabilize both walking and running and this coordination is stronger in walking than in running.
It is still unclear how humans control mediolateral (ML) stability in walking and even more so for running. Here, foot placement strategy as a main mechanism to control ML stability was compared between walking and running. Moreover, to verify the role of foot placement as a means to control ML stability in both modes of locomotion, this study investigated the effect of external lateral stabilization on foot placement control. Ten young adults participated in this study. Kinematic data of the trunk (T6) and feet were recorded during walking and running on a treadmill in normal and stabilized conditions. Correlation between ML trunk CoM state and subsequent ML foot placement, step width, and step width variability were assessed. Paired t-tests (either SPM1d or normal) were used to compare aforementioned parameters between normal walking and running. Two-way repeated measures ANOVAs (either SPM1d or normal) were used to test for effects of walking vs. running and of normal vs. stabilized condition. We found a stronger correlation between ML trunk CoM state and ML foot placement and significantly higher step width and step width variability in walking than in running. The correlation between ML trunk CoM state and ML foot placement, step width, and step width variability were significantly decreased by external lateral stabilization in walking and running, and this reduction was stronger in walking than in running. We conclude that ML foot placement is coordinated to ML trunk CoM state to stabilize both walking and running and this coordination is stronger in walking than in running.The detection of trans gene fragments of hEPO in gene doping model mice by Taqman qPCR assayhttps://peerj.com/preprints/279252019-08-292019-08-29Kai AokiTakehito SugasawaKouki YanazawaKoichi WatanabeTohru TakemasaYoshinori TakeuchiYuichi AitaNaoya YahagiYasuko YoshidaTomoaki KujiNanami SekineKaoru TakeuchiHaruna UedaYasushi KawakamiKazuhiro Takekoshi
BACKGROUND. With the rapid progress of genetic engineering and gene therapy methods, the World Anti-Doping Agency has raised concerns regarding gene doping, which is prohibited in sports. However, there is no standard method available for detecting transgenes delivered by injection of naked plasmids. Here, we developed a detection method for detecting transgenes delivered by injection of naked plasmids in a mouse model that mimics gene doping. METHODS. Whole blood from the tail tip and one piece of stool were used as pre-samples of injection. Next, a plasmid vector containing the human erythropoietin (hEPO) gene was injected into mice through intravenous (IV), intraperitoneal (IP), or local muscular (IM) injection. At 1, 2, 3, 6, 12, 24, and 48 h after injection, approximately 50 μL whole blood was collected from the tail tip. One piece of stool was collected at 6, 12, 24, and 48 h. From each sample, total DNA was extracted and transgene fragments were analyzed by Taqman quantitative PCR (qPCR) and SYBR green qPCR. RESULTS. In whole blood DNA samples evaluated by Taqman qPCR, the transgene fragments were detected at all time points in the IP sample and at 1, 2, 3, 6, and 12 h in the IV and IM samples. In the stool-DNA samples, the transgene fragments were detected at 6, 12, 24, and 48 h in the IV and IM samples by Taqman qPCR. In the analysis by SYBR green qPCR, the transgene fragments were detected at some time point in both specimens; however, many non-specific amplicons were detected. CONCLUSIONS. These results indicate that transgene fragments evaluated after each injection method of naked plasmids were detected in whole-blood and stool DNA samples. These findings may facilitate the development of methods for detecting gene doping.
BACKGROUND. With the rapid progress of genetic engineering and gene therapy methods, the World Anti-Doping Agency has raised concerns regarding gene doping, which is prohibited in sports. However, there is no standard method available for detecting transgenes delivered by injection of naked plasmids. Here, we developed a detection method for detecting transgenes delivered by injection of naked plasmids in a mouse model that mimics gene doping. METHODS. Whole blood from the tail tip and one piece of stool were used as pre-samples of injection. Next, a plasmid vector containing the human erythropoietin (hEPO) gene was injected into mice through intravenous (IV), intraperitoneal (IP), or local muscular (IM) injection. At 1, 2, 3, 6, 12, 24, and 48 h after injection, approximately 50 μL whole blood was collected from the tail tip. One piece of stool was collected at 6, 12, 24, and 48 h. From each sample, total DNA was extracted and transgene fragments were analyzed by Taqman quantitative PCR (qPCR) and SYBR green qPCR. RESULTS. In whole blood DNA samples evaluated by Taqman qPCR, the transgene fragments were detected at all time points in the IP sample and at 1, 2, 3, 6, and 12 h in the IV and IM samples. In the stool-DNA samples, the transgene fragments were detected at 6, 12, 24, and 48 h in the IV and IM samples by Taqman qPCR. In the analysis by SYBR green qPCR, the transgene fragments were detected at some time point in both specimens; however, many non-specific amplicons were detected. CONCLUSIONS. These results indicate that transgene fragments evaluated after each injection method of naked plasmids were detected in whole-blood and stool DNA samples. These findings may facilitate the development of methods for detecting gene doping.Modelling the effect of curves on distance running performancehttps://peerj.com/preprints/278842019-08-062019-08-06Paolo TabogaRodger Kram
Background On a curve, the average axial leg force (Fa) of a runner is increased due to the need to exert centripetal force. The increased Fa presumably requires a greater rate of metabolic energy expenditure than straight running at the same velocity. We propose a model that explains the velocity reduction on curves, compared to straight running, assuming that runners maintain a constant metabolic rate.
Methods We combined published equations to estimate the change in the rate of gross metabolic energy expenditure as a function of Fa, where Fa depends on curve radius and velocity, with an equation for the gross rate of oxygen uptake as a function of velocity. We compared performances between straight courses and courses with different curve radii and geometries.
Results The differences between our model predictions and the actual indoor world records, are between 0.45 % in 3000 m and 1.78 % in the 1500 m for males, and 0.59 % in the 5000 m and 1.76 % in the 3000 m for females. We estimate thata 2:01:39 marathon on a 400 m track, corresponds to 2:01:32 on a straight path and to 2:02:00 on a 200 m track.
Conclusion Our model predicts that compared to straight racecourses, the increased time due to curves, is notable for smaller curve radii and for faster velocities. But, for larger radii and slower speeds, the time increase is negligible and the general perception of the magnitude of the effects of curves on road racing performance is not supported by our calculations.
Background On a curve, the average axial leg force (Fa) of a runner is increased due to the need to exert centripetal force. The increased Fa presumably requires a greater rate of metabolic energy expenditure than straight running at the same velocity. We propose a model that explains the velocity reduction on curves, compared to straight running, assuming that runners maintain a constant metabolic rate.Methods We combined published equations to estimate the change in the rate of gross metabolic energy expenditure as a function of Fa, where Fa depends on curve radius and velocity, with an equation for the gross rate of oxygen uptake as a function of velocity. We compared performances between straight courses and courses with different curve radii and geometries.Results The differences between our model predictions and the actual indoor world records, are between 0.45 % in 3000 m and 1.78 % in the 1500 m for males, and 0.59 % in the 5000 m and 1.76 % in the 3000 m for females. We estimate thata 2:01:39 marathon on a 400 m track, corresponds to 2:01:32 on a straight path and to 2:02:00 on a 200 m track.Conclusion Our model predicts that compared to straight racecourses, the increased time due to curves, is notable for smaller curve radii and for faster velocities. But, for larger radii and slower speeds, the time increase is negligible and the general perception of the magnitude of the effects of curves on road racing performance is not supported by our calculations.Complexity of human walking: the attractor complexity index is sensitive to gait synchronization with visual and auditory cueshttps://peerj.com/preprints/277112019-05-072019-05-07Philippe Terrier
Background. During steady walking, gait parameters fluctuate from one stride to another with complex fractal patterns and long-range statistical persistence. When a metronome is used to pace the gait (sensorimotor synchronization), long-range persistence is replaced by stochastic oscillations (anti-persistence). Fractal patterns present in gait fluctuations are most often analyzed using detrended fluctuation analysis (DFA). This method requires the use of a discrete times series, such as intervals between consecutive heel strikes, as an input. Recently, a new nonlinear method, the attractor complexity index (ACI), has been shown to respond to complexity changes like DFA. But in contrast to DFA, ACI can be applied to continuous signals, such as body accelerations. The aim of this study was to further compare DFA and ACI in a treadmill experiment that induced complexity changes through sensorimotor synchronization. Methods. Thirty-six healthy adults walked 30 minutes on an instrumented treadmill under three conditions: no cueing, auditory cueing (metronome walking), and visual cueing (stepping stones). The center-of-pressure trajectory was discretized into time series of gait parameters, after which a complexity index (scaling exponent alpha) was computed via DFA. Continuous pressure position signals were used to compute the ACI. Correlations between ACI and DFA were then analyzed. The predictive ability of DFA and ACI to differentiate between cueing and no-cueing conditions was assessed using regularized logistic regressions and areas under the receiver operating characteristic curves (AUROC). Results. DFA and ACI were both significantly different among the cueing conditions. DFA and ACI were correlated (Pearson’s r = 0.78). Logistic regressions showed that DFA and ACI could differentiate between cueing/no cueing conditions with a high degree of confidence (AUROC = 1.0 and 0.96, respectively). Conclusion. Both DFA and ACI responded similarly to changes in cueing conditions and had comparable predictive power. This support the assumption that ACI could be used instead of DFA to assess the long-range complexity of continuous gait signals.
Background. During steady walking, gait parameters fluctuate from one stride to another with complex fractal patterns and long-range statistical persistence. When a metronome is used to pace the gait (sensorimotor synchronization), long-range persistence is replaced by stochastic oscillations (anti-persistence). Fractal patterns present in gait fluctuations are most often analyzed using detrended fluctuation analysis (DFA). This method requires the use of a discrete times series, such as intervals between consecutive heel strikes, as an input. Recently, a new nonlinear method, the attractor complexity index (ACI), has been shown to respond to complexity changes like DFA. But in contrast to DFA, ACI can be applied to continuous signals, such as body accelerations. The aim of this study was to further compare DFA and ACI in a treadmill experiment that induced complexity changes through sensorimotor synchronization. Methods. Thirty-six healthy adults walked 30 minutes on an instrumented treadmill under three conditions: no cueing, auditory cueing (metronome walking), and visual cueing (stepping stones). The center-of-pressure trajectory was discretized into time series of gait parameters, after which a complexity index (scaling exponent alpha) was computed via DFA. Continuous pressure position signals were used to compute the ACI. Correlations between ACI and DFA were then analyzed. The predictive ability of DFA and ACI to differentiate between cueing and no-cueing conditions was assessed using regularized logistic regressions and areas under the receiver operating characteristic curves (AUROC). Results. DFA and ACI were both significantly different among the cueing conditions. DFA and ACI were correlated (Pearson’s r = 0.78). Logistic regressions showed that DFA and ACI could differentiate between cueing/no cueing conditions with a high degree of confidence (AUROC = 1.0 and 0.96, respectively). Conclusion. Both DFA and ACI responded similarly to changes in cueing conditions and had comparable predictive power. This support the assumption that ACI could be used instead of DFA to assess the long-range complexity of continuous gait signals.Characteristics of effective home-based resistance training exercise in patients with chronic disease: a scoping review protocolhttps://peerj.com/preprints/276792019-04-242019-04-24Thomas WilkinsonRoseanne BillanyCourtney J LightfootMatthew Graham-BrownAlice C Smith
Regular exercise, principally resistance training, is an effective method to promote muscle hypertrophy and attenuate muscle atrophy during various atrophic conditions . There is growing interest in the evaluation of home-based resistance training programmes. These programmes have the potential to overcome common barriers to participation, such as accessibility and affordability. The objective of the scoping review is to map the available evidence to provide an overview of what characteristics, principles, and components are required for an effective home-based resistance training programme in patients with chronic disease. The four specific objectives of the scoping review will be to: 1) conduct a systematic search of the published and grey literature for studies reporting on home-based resistance training in patients with chronic disease; 2) map out the characteristics and range of methodologies (including exercise protocols and outcome measures) used in effective home-based resistance training; 3) examine reported challenges and limitations of home-based resistance training; and 4) propose recommendations for optimizing home-based resistance training protocols in this population.
Regular exercise, principally resistance training, is an effective method to promote muscle hypertrophy and attenuate muscle atrophy during various atrophic conditions . There is growing interest in the evaluation of home-based resistance training programmes. These programmes have the potential to overcome common barriers to participation, such as accessibility and affordability. The objective of the scoping review is to map the available evidence to provide an overview of what characteristics, principles, and components are required for an effective home-based resistance training programme in patients with chronic disease. The four specific objectives of the scoping review will be to: 1) conduct a systematic search of the published and grey literature for studies reporting on home-based resistance training in patients with chronic disease; 2) map out the characteristics and range of methodologies (including exercise protocols and outcome measures) used in effective home-based resistance training; 3) examine reported challenges and limitations of home-based resistance training; and 4) propose recommendations for optimizing home-based resistance training protocols in this population.motoRneuron: an open-source R toolbox for time-domain motor unit analyseshttps://peerj.com/preprints/275782019-03-112019-03-11Andrew J TweedellMatthew S Tenan
Motor unit synchronization is the tendency of motor neurons and their associated muscle fibers to discharge near-simultaneously. It has been theorized as a control mechanism for force generation by common excitatory inputs to these motor neurons. Magnitude of synchronization is calculated from peaks in cross-correlation histograms between motor unit discharge trains. However, there are many different methods for detecting these peaks and even more indices for calculating synchronization from them. Methodology is typically laboratory-specific and requires expensive software, like Matlab or LabView. This lack of standardization makes it difficult to draw definitive conclusions about motor unit synchronization. To combat this, we have developed a freely available, open-source toolbox, “motoRneuron”, for the R programming language. This toolbox contains functions for calculating time domain synchronization using different methods found in the literature. Our objective is to detail the program’s functionality and provide a clear use-case for implementation. The programs primary function “mu_synch” automatically performs the cross-correlation analysis based on user input. Automated peak detection methods such as the cumulative sum method and the z-score method, as well as subjective, visual analysis are available. Users can also define other parameters like the number of recurrence intervals to be used and histogram bin size. The function outputs six common synchronization indices, the common input strength (CIS), k’, k’-1, E, S, and Synch Index. This toolbox allows for better standardization of techniques and for more comprehensive data mining in the motor control community.
Motor unit synchronization is the tendency of motor neurons and their associated muscle fibers to discharge near-simultaneously. It has been theorized as a control mechanism for force generation by common excitatory inputs to these motor neurons. Magnitude of synchronization is calculated from peaks in cross-correlation histograms between motor unit discharge trains. However, there are many different methods for detecting these peaks and even more indices for calculating synchronization from them. Methodology is typically laboratory-specific and requires expensive software, like Matlab or LabView. This lack of standardization makes it difficult to draw definitive conclusions about motor unit synchronization. To combat this, we have developed a freely available, open-source toolbox, “motoRneuron”, for the R programming language. This toolbox contains functions for calculating time domain synchronization using different methods found in the literature. Our objective is to detail the program’s functionality and provide a clear use-case for implementation. The programs primary function “mu_synch” automatically performs the cross-correlation analysis based on user input. Automated peak detection methods such as the cumulative sum method and the z-score method, as well as subjective, visual analysis are available. Users can also define other parameters like the number of recurrence intervals to be used and histogram bin size. The function outputs six common synchronization indices, the common input strength (CIS), k’, k’-1, E, S, and Synch Index. This toolbox allows for better standardization of techniques and for more comprehensive data mining in the motor control community.An automatic fascicle tracking algorithm quantifying gastrocnemius architecture during maximal effort contractionshttps://peerj.com/preprints/274752019-01-102019-01-10John F DrazanTodd J HullfishJosh R Baxter
Background. Ultrasound has become the gold-standard for making dynamic measurements of muscle structure during functional movements in biomechanical studies. Manual measurements of fascicle length and pennation angle are time intensive which limits the clinical utility of this approach while also limiting sample sizes. The purpose of this study was to develop a novel tracking paradigm to quantify individual fascicle length and pennation measurements during maximal voluntary contractions and demonstrate is repeatability between days and reproducibility between different examiners.
Methods. Five healthy young adults performed maximal isokinetic contractions at 0, 30, 120, 210, and 500 degrees about their ankle on an isokinetic dynamometer while their gastrocnemius muscle was observed using ultrasound. Individual muscle fascicles were identified in the first frame, and tracked using the automatic fascicle tracking algorithm and a manual approach by three observers on three separate days. Repeatability within examiners across days and reproducibility across examiners and days was evaluated using intraclass correlation coefficients. Agreement between manual and automatic tracking was evaluated using the coefficient of multiple correlations. Supervised automatic tracking was performed on all videos by one examiner to evaluate the fidelity of automatic tracking in practice.
Results. We found both manual and automatic measurements of fascicle length and pennation angle to be strongly repeatable within examiners and strongly reproducible across examiners and days (ICCs>0.76). There was greater agreement between manual and automatic measurements of fascicle length than pennation angle, however the mean CMC value for both was still found to be strong in both cases (CMC>0.8). Supervision of automatic tracking greatly showed very strong agreement between manual and automatic measurements of fascicle length and pennation angle (CMC>0.94).
Conclusions. We have developed a novel automatic fascicle tracking algorithm that quantifies fascicle length and pennation angle of individual muscle fascicles during dynamic contractions across a range of velocities. We demonstrated that this fascicle tracking algorithm is repeatable and reproducible across different examiners and different days and showed strong agreement with manual measurements, especially when tracking is supervised by the user so that tracking can be reinitialized if poor tracking fidelity is observed.
Background. Ultrasound has become the gold-standard for making dynamic measurements of muscle structure during functional movements in biomechanical studies. Manual measurements of fascicle length and pennation angle are time intensive which limits the clinical utility of this approach while also limiting sample sizes. The purpose of this study was to develop a novel tracking paradigm to quantify individual fascicle length and pennation measurements during maximal voluntary contractions and demonstrate is repeatability between days and reproducibility between different examiners.Methods. Five healthy young adults performed maximal isokinetic contractions at 0, 30, 120, 210, and 500 degrees about their ankle on an isokinetic dynamometer while their gastrocnemius muscle was observed using ultrasound. Individual muscle fascicles were identified in the first frame, and tracked using the automatic fascicle tracking algorithm and a manual approach by three observers on three separate days. Repeatability within examiners across days and reproducibility across examiners and days was evaluated using intraclass correlation coefficients. Agreement between manual and automatic tracking was evaluated using the coefficient of multiple correlations. Supervised automatic tracking was performed on all videos by one examiner to evaluate the fidelity of automatic tracking in practice.Results. We found both manual and automatic measurements of fascicle length and pennation angle to be strongly repeatable within examiners and strongly reproducible across examinersand days (ICCs>0.76). There was greater agreement between manual and automatic measurements of fascicle length than pennation angle, however the mean CMC value for both was still found to be strong in both cases (CMC>0.8). Supervision of automatic tracking greatly showed very strong agreement between manual and automatic measurements of fascicle length and pennation angle (CMC>0.94).Conclusions. We have developed a novel automatic fascicle tracking algorithm that quantifies fascicle length and pennation angle of individual muscle fascicles during dynamic contractions across a range of velocities. We demonstrated that this fascicle tracking algorithm is repeatable and reproducible across different examiners and different days and showed strong agreement with manual measurements, especially when tracking is supervised by the user so that tracking can be reinitialized if poor tracking fidelity is observed.Should agility training for novice badminton players be physically or perceptually challenging?https://peerj.com/preprints/273592018-11-192018-11-19Minkai DongJidong LyuThomas HartQin Zhu
Background. Despite its well-known importance in sports, agility is ambiguously defined and lack of research. Shuttle Run (SR) challenges physical quickness and is commonly used to improve the on-court agility of badminton players. In contrast, Reactive Initiation Training (RIT) challenges perceptual quickness, merely demanding rapid initiation of step toward the direction of shuttlecock. The current study compared SR with RIT to determine which one is more effective for improving on-court agility of novice badminton players. Methods. 20 novice badminton players were split in half to receive either RIT or SR on court for five days. Before and after training, participants were assessed on their ability to intercept the shuttlecocks randomly thrown by a coach to six corners of the court with and without visual occlusion of the coach. All trials of interception were videotaped by a motion camera for chronological analysis of initiation time, running time and total time. Results. The mean total times were greater with visual occlusion and varied systematically with the position of interception. Both training methods shortened the mean running time, however, only RIT additionally reduced the initiation time and its proportion on those time-consuming positions in the occluded condition. Therefore, RIT is more effective than SR to improve the on-court agility of novice badminton players, and the agility training for novice badminton players should be more perceptually than physically challenging to avoid vain effort and unnecessary injuries.
Background. Despite its well-known importance in sports, agility is ambiguously defined and lack of research. Shuttle Run (SR) challenges physical quickness and is commonly used to improve the on-court agility of badminton players. In contrast, Reactive Initiation Training (RIT) challenges perceptual quickness, merely demanding rapid initiation of step toward the direction of shuttlecock. The current study compared SR with RIT to determine which one is more effective for improving on-court agility of novice badminton players. Methods. 20 novice badminton players were split in half to receive either RIT or SR on court for five days. Before and after training, participants were assessed on their ability to intercept the shuttlecocks randomly thrown by a coach to six corners of the court with and without visual occlusion of the coach. All trials of interception were videotaped by a motion camera for chronological analysis of initiation time, running time and total time. Results. The mean total times were greater with visual occlusion and varied systematically with the position of interception. Both training methods shortened the mean running time, however, only RIT additionally reduced the initiation time and its proportion on those time-consuming positions in the occluded condition. Therefore, RIT is more effective than SR to improve the on-court agility of novice badminton players, and the agility training for novice badminton players should be more perceptually than physically challenging to avoid vain effort and unnecessary injuries.Compatibility between object size and response side in grasping: The left hand prefers smaller objects, the right hand prefers larger objectshttps://peerj.com/preprints/271942018-09-122018-09-12Christian SeegelkePeter Wühr
It has been proposed that the brain processes quantities such as space, size, number, and other magnitudes using a common neural metric, and that this common representation system reflects a direct link to motor control, because the integration of spatial, temporal, and other quantity-related information is fundamental for sensorimotor transformation processes. In the present study, we examined compatibility effects between physical stimulus size and spatial (response) location during a sensorimotor task. Participants reached and grasped for a small or large object with either their non-dominant left or their dominant right hand. Our results revealed that participants initiated left hand movements faster when grasping the small cube compared to the large cube, whereas they initiated right hand movements faster when grasping the large cube compared to the small cube. Moreover, the compatibility effect influenced the timing of grip aperture kinematics. These findings indicate that the interaction between object size and response hand affects the planning of grasping movements and supports the notion of a strong link between the cognitive representation of (object) size, spatial (response) parameters, and sensorimotor control.
It has been proposed that the brain processes quantities such as space, size, number, and other magnitudes using a common neural metric, and that this common representation system reflects a direct link to motor control, because the integration of spatial, temporal, and other quantity-related information is fundamental for sensorimotor transformation processes. In the present study, we examined compatibility effects between physical stimulus size and spatial (response) location during a sensorimotor task. Participants reached and grasped for a small or large object with either their non-dominant left or their dominant right hand. Our results revealed that participants initiated left hand movements faster when grasping the small cube compared to the large cube, whereas they initiated right hand movements faster when grasping the large cube compared to the small cube. Moreover, the compatibility effect influenced the timing of grip aperture kinematics. These findings indicate that the interaction between object size and response hand affects the planning of grasping movements and supports the notion of a strong link between the cognitive representation of (object) size, spatial (response) parameters, and sensorimotor control.