Rise rate and timing variability of surface electromyographic activity during rhythmic drumming movements in the world's fastest drummer

What are the kinematic characteristics of the world champion couple in competitive ballroom dance during the waltz's spin movement?

To evaluate competitive ballroom dancing, one of the official events of the World Games, spin movements used by advanced dancers who ranked high in actual competition may be employed. The purpose of this study was to investigate the kinematic characteristics of spin movements in competitive ballroom dancing performed by world champion couples, especially holding posture and lower limb movements. A champion couple and 13 national-level competitive ballroom dancers as the control group participated in this study. An inertial measurement unit (IMU) system (MVN Link; Xsens, Netherlands) consisting of 17 IMUs, attached to feet, shanks, thighs, pelvis, sternum, head, upper arms, forearms, and hands of the dancers, was used to obtain three-dimensional kinematic data at 240 Hz. The overall trend was that the actual and normalized stride lengths of the champion male and female dancers tended to be longer than those of the male and female dancers in the control group. Further, large differences were observed in the pelvic and rib cage segments movements, and the relative angle of the rib cage segment to the pelvic segment. The champion male dancer started to move from the pelvic segment, whereas the champion female dancer and the national-level top male and female dancers started to move from the rib cage segment. During the spin movement, the champion male dancer was in a position where the rib cage segment was rotated to the left with respect to the pelvic segment, whereas the other dancers were in a position where the rib cage segment was rotated to the right. Although limited to technical aspects, these dance kinematic characteristics of the world champion couples and their differences from those of the control group dancers, will be helpful to competitive ballroom dancers and coaches in their daily practice.

Tapping Performance of Professional and Amateur Darbuka Players

Motor skills of professional musicians can be regarded as a model to investigate human skill acquisition after prolonged practice. Although rhythmic tapping skills of musicians such as drummers and pianists were investigated previously, the tapping performance of hand percussionists is still largely unknown. In this study, we investigated the tapping performance of professional and amateur darbuka players. Three tapping tasks were performed: single-, double-, and triple-finger tapping tasks. The participants were asked to tap as fast as possible for 12 s in the single-finger tapping task while they tapped as fast and alternate/even as possible in the double- and triple-finger tapping tasks. The tapping speed and variability of inter-tap interval (ITI) and tapping amplitude were assessed for each task. In the single-finger and triple-finger tapping tasks, there was no significant difference in the tapping speed between the professional and amateur darbuka players. In the double-finger tapping task, the tapping speed was significantly faster in the professional players than the amateur players. Interestingly, the professional players showed faster tapping speed in both familiar and unfamiliar patterns of finger coordination. The tapping speed of the double-finger tapping task was significantly correlated with the duration and the age of commencement of darbuka training. The professional players also showed less variability of ITI and tapping amplitude compared to the amateur players. These results suggest that prolonged practice of the hand percussion increases the performance stability and coordination speed of both familiar and unfamiliar patterns.

Expertise- and Tempo-Related Performance Differences in Unimanual Drumming

BACKGROUND

High-speed drumming requires precise control over the timing, velocity, and magnitude of striking movements.

AIM

To examine effects of tempo and expertise on unaccented repetitive drumming performance using 3D motion capture.

METHODS

Expert and amateur drummers performed unimanual, unaccented, repetitive drum strikes, using their dominant right hand, at five different tempi. Performance was examined with regard to timing variability, striking velocity variability, the ability to match the prescribed tempo, and additional variables.

RESULTS

Permutated multivariate analysis of variance (PERMANOVA) revealed significant main effects of tempo (p < .001) and expertise (p <.001) on timing variability and striking velocity variability; low timing variability and low striking velocity variability were associated with low/medium tempo as well as with increased expertise. Individually, improved precision appeared across an optimum tempo range. Precision was poorest at maximum tempo (400 hits per minute) for precision variables.

CONCLUSIONS

Expert drummers demonstrated greater precision and consistency than amateurs. Findings indicate an optimum tempo range that extends with increased expertise.

Timing of Rectus Femoris and Biceps Femoris Muscle Activities in Both Legs at Maximal Running Speed

PURPOSE

The purpose of this study was to investigate the relationship between spatiotemporal variables of running and onset/offset timing of rectus femoris (RF) and biceps femoris (BF) muscle activities in both legs.

METHODS

Eighteen male well-trained athletes (age = 20.7 ± 1.8 yr) were asked to run 50 m at maximal speed. The spatiotemporal variables (running speed, step frequency, and step length) over the distance from 30 to 50 m were measured. In addition, RF and BF muscle activities were obtained from both legs using wireless EMG sensors. To quantify the onset and offset timing of muscle activity, the band-pass filtered (20-450 Hz) EMG signal was processed using a Teager-Kaiser energy operator filter. We calculated RF and BF onset/offset timings (%) in both legs (e.g., ipsilateral leg RF [iRF] and contralateral leg BF [cBF]) during running cycle. Based on those timings, we obtained the EMG timing variables (%) as follows: "Switch1 (iBF-offset to iRF-onset)," "Switch2 (iRF-offset to iBF-onset)," "Scissors1 (cBF-onset to iRF-onset)," and "Scissors2 (iRF-offset to cBF-offset).

RESULTS

We found that "Switch2" had positive (r = 0.495, P = 0.037), "Scissors1" had negative (r = -0.469, P = 0.049), and "Scissors2" had positive (r = 0.574, P = 0.013) correlations with step frequency. However, these variables had no significant correlations with running speed or step length.

CONCLUSIONS

These results indicate that higher step frequency would be achieved by smoother switching of the agonist-antagonist muscle activities and earlier iRF activation relative to the cBF activity. To improve sprint performance, athletes and coaches should consider not only muscle activities in one leg but also coordination of muscle activities in both legs.

Finger-to-Beat Coordination Skill of Non-dancers, Street Dancers, and the World Champion of a Street-Dance Competition

The coordination of body movements to a musical beat is a common feature of many dance styles. However, the auditory-motor coordination skills of dancers remain largely uninvestigated. The purpose of this study was to examine the auditory-motor coordination skills of non-dancers, street dancers, and the winner of a celebrated international street dance competition, while coordinating their rhythmic finger movements to a beat. The beat rate of a metronome increased from 1.0 to 3.7 Hz. The participants were asked to either flex or extend their index fingers on the beat in each condition. Under the extend-on-the-beat condition, both the dancers and non-dancers showed a spontaneous transition from the extend-on-the-beat to the flex-on-the-beat or to a phase wandering pattern. However, the critical frequency at which the transition occurred was significantly higher in the dancers (3.3 Hz) than in the non-dancers (2.6 Hz). Under the flex-on-the-beat condition, the dancers were able to maintain their coordination pattern more stably at high beat rates compared to the non-dancers. Furthermore, the world champion matched the timing of movement peak velocity to the beat across the different beat rates. This may give a sense of unity between the movement and the beat for the audience because the peak velocity of the rhythmic movement works as a temporal cue for the audiovisual synchrony perception. These results suggest that the skills of accomplished dancers lie in their small finger movements and that the sensorimotor learning of street dance is characterized by a stabilization of the coordination patterns, including the inhibition of an unintentional transition to other coordination patterns.

Flexibility of movement organization in piano performance

Piano performance involves a large repertoire of highly skilled movements. The acquisition of these exceptional skills despite innate neural and biomechanical constraints requires a sophisticated interaction between plasticity of the neural system and organization of a redundant number of degrees of freedom (DOF) in the motor system. Neuroplasticity subserving virtuosity of pianists has been documented in neuroimaging studies investigating effects of long-term piano training on structure and function of the cortical and subcortical regions. By contrast, recent behavioral studies have advanced the understanding of neuromuscular strategies and biomechanical principles behind the movement organization that enables skilled piano performance. Here we review the motor control and biomechanics literature, introducing the importance of describing motor behaviors not only for understanding mechanisms responsible for skillful motor actions in piano playing, but also for advancing diagnosis and rehabilitation of movement disorders caused by extensive piano practice.

Spike shape analysis of surface electromyographic activity in wrist flexor and extensor muscles of the world's fastest drummer

Spike shape analysis (SSA) is a method to infer motor unit (MU) activity by examining interference pattern of surface electromyography (sEMG). SSA has succeeded to assess neuromuscular adaptations after dynamic training; however, it has not been used to assess muscle activities during the dynamic movements as seen in music performance. The present study used SSA to investigate sEMG activities of wrist flexor and extensor muscles in the winner of a contest to find the world's fastest drummer (WFD) during performing rhythmic wrist flexion/extension movements with one hand using a handheld drumstick. SSA measures of the WFD were compared with those in the two control groups: non-drummers (NDs) and ordinary drummers (ODs). We found that the WFD showed significantly high mean spike frequency (MSF), short mean spike duration (MSD), and small mean number of peaks per spike (MNPPS) compared with the control groups. These results suggest that the WFD had exceptional MU activity such as higher MU discharge rate, more MU recruitment, and/or higher MU synchronization to achieve extraordinary fast 10-Hz drumming performance. SSA will be useful to investigate the muscle activity seen in music performance.