Mutual stabilization of rhythmic vocalization and whole-body movement

Comparing the effect of rhythmic stabilization and combination of isotonic technique on grip strength, pinch strength and dexterity of hand among middle aged healthy individuals - a randomized clinical trial

Purpose: The aim of the study was to evaluate and compare the effects of Rhythmic Stabilization and a combination of isotonic technique on grip  strength, pinch strength, and dexterity of hand among middle aged healthy individuals. Methods Forty middle aged healthy individuals were selected on the basis of inclusion and exclusion criteria. Participants were randomly allocated to two groups, with 20 in group A (Rhythmic Stabilization) and 20 in group B (Combination of Isotonic Technique). Treatment was given for 4 weeks, thrice a week. Outcome measures: grip strength, pinch strength, and dexterity were assessed by the Jamar hand dynamometer, the Pinch gauge, and the Perdue peg board, respectively. Outcome measures were assessed at baseline and after 4 weeks of treatment. Results Notably, Group A participants showed a significant improvement in all outcome measures compared to Group B (p<0.05) when compared. Both the interventions were effective for dexterity outcome in both groups (p<0.05).  Conclusion: This study provides evidence that application of Rhythmic Stabilization improves grip strength and pinch strength.  This suggests that static Proprioceptive Neuromuscular Facilitation (PNF) exercises performed on the fingers can improve dexterity, grip strength, and pinch strength in the middle-aged population. Highlights As age increases, there is decrease in grip strength and dexterity of a person. The grip strength, finger strength and dexterity are inter-related. The Proprioceptive Neuromuscular Facilitation increases strength of muscles. The static PNF exercises are more effective than the dynamic PNF exercises to improve strength of grip strength, finger strength and dexterity.

Coordination dynamics of thoracic and abdominal movements during voluntary breathing

Thoracic and abdominal movements can be tightly coupled during voluntary breathing, such as when singing and playing wind instruments. The present study investigated the coordination of thoracic and abdominal movements during voluntary breathing using a dynamical systems approach. We examined whether there are two stable coordination patterns, and if the coordination pattern would abruptly change when the breathing frequency increased, which is known as phase transition. The participants inhaled and exhaled repeatedly at 7.5, 15, 30, 60, or 120 breaths per minute. At the beginning and end of the experiment, the participants performed breathing at their preferred frequency. As a result, the coordination pattern at the lower and preferred frequencies exhibited an in-phase pattern. When breathing frequency increased, participants showed deviated coordination patterns from the in-phase pattern to either a thoracic-leading pattern, an abdominal-leading pattern, or an anti-phase pattern depending on the individual. These deviations occurred gradually; thus, phase transition was not observed. Our findings suggest that thoracic and abdominal movements are tightly coupled at lower frequencies, but their patterns vary depending on the breathing frequency and individuals. Therefore, the present study suggests the importance of viewing breath control in terms of coordination of thoracic and abdominal movements.

Coordination of voice, hands and feet in rhythm and beat performance

Interlimb coordination is critical to the successful performance of simple activities in everyday life and it depends on precisely timed perception–action coupling. This is particularly true in music-making, where performers often use body-movements to keep the beat while playing more complex rhythmic patterns. In the current study, we used a musical rhythmic paradigm of simultaneous rhythm/beat performance to examine how interlimb coordination between voice, hands and feet is influenced by the inherent figure-ground relationship between rhythm and beat. Sixty right-handed participants—professional musicians, amateur musicians and non-musicians—performed three short rhythmic patterns while keeping the underlying beat, using 12 different combinations of voice, hands and feet. Results revealed a bodily hierarchy with five levels (1) left foot, (2) right foot, (3) left hand, (4) right hand, (5) voice, i.e., more precise task execution was observed when the rhythm was performed with an effector occupying a higher level in the hierarchy than the effector keeping the beat. The notion of a bodily hierarchy implies that the role assigned to the different effectors is key to successful interlimb coordination: the performance level of a specific effector combination differs considerably, depending on which effector holds the supporting role of the beat and which effector holds the conducting role of the rhythm. Although performance generally increased with expertise, the evidence of the hierarchy was consistent in all three expertise groups. The effects of expertise further highlight how perception influences action. We discuss the possibility that musicians’ more robust metrical prediction models make it easier for musicians to attenuate prediction errors than non-musicians. Overall, the study suggests a comprehensive bodily hierarchy, showing how interlimb coordination is influenced by hierarchical principles in both perception and action.

Audiovisual synchrony perception in observing human motion to music

To examine how individuals perceive synchrony between music and body motion, we investigated the characteristics of synchrony perception during observation of a Japanese Radio Calisthenics routine. We used the constant stimuli method to present video clips of an individual performing an exercise routine. We generated stimuli with a range of temporal shifts between the visual and auditory streams, and asked participants to make synchrony judgments. We then examined which movement-feature points agreed with music beats when the participants perceived synchrony. We found that extremities (e.g., hands and feet) reached the movement endpoint or moved through the lowest position at music beats associated with synchrony. Movement onsets never agreed with music beats. To investigate whether visual information about the feature points was necessary for synchrony perception, we conducted a second experiment where only limited portions of video clips were presented to the participants. Participants consistently judged synchrony even when the video image did not contain the critical feature points, suggesting that a prediction mechanism contributes to synchrony perception. To discuss the meaning of these feature points with respect to synchrony perception, we examined the temporal relationship between the motion of body parts and the ground reaction force (GRF) of exercise performers, which reflected the total force acting on the performer. Interestingly, vertical GRF showed local peaks consistently synchronized with music beats for most exercises, with timing that was closely correlated with the timing of movement feature points. This result suggests that synchrony perception in humans is based on some global variable anticipated from visual information, instead of the feature points found in the motion of individual body parts. In summary, the present results indicate that synchrony perception during observation of human motion to music depends largely on spatiotemporal prediction of the performer's motion.

Accent Stabilizes 1:2 Sensorimotor Synchronization of Rhythmic Knee Flexion-Extension Movement in Upright Stance

Numerous studies have shown the importance of metrical structure on beat perception and sensorimotor synchronization (SMS), which indicates why metrical structure has evolved as a widespread musical element. In the current study, we aimed to investigate the effect of metrical structure with or without accented sounds and the alignment of accent with flexion or extension movements on the stability of 1:2 SMS in rhythmic knee flexion-extension movement in upright stance (flexing the knee once every two sounds). Fourteen participants completed 1:2 rhythmic knee flexion-extension movements with a metronome beat that accelerated from 2 to 8 Hz (the frequency of the movement was 1–4 Hz). Three sound-movement conditions were provided: (1) combining the flexion phase with loud (accented) sound and the extension phase with soft (non-accented) sound, (2) the reverse combination, and (3) combining both movements with loud sound. ANOVA results showed that metrical structure with accented sounds stabilizes 1:2 SMS in the range of 3.5–7.8 Hz in terms of timing accuracy, and flexing on the accented sound is more globally stable (resistant to phase transition) than flexing on the non-accented sound. Furthermore, our results showed that metrical structure with accented sounds induces larger movement amplitude in the range of 4.6–7.8 Hz than does that without accented sounds. The present study demonstrated that metrical structure with accented sounds stabilizes SMS and induces larger movement amplitude in rhythmic knee flexion-extension movement in upright stance than does SMS with sequences without accents. In addition, we demonstrated that coordinating flexion movement with accented sound is more globally stable than coordinating extension movement with accented sound. Thus, whereas previous studies have revealed that metrical structure enhances the timing accuracy of SMS, the current study revealed that metrical structure enhances the global stability of SMS.

Internal cueing improves gait more than external cueing in healthy adults and people with Parkinson disease

Walking can be challenging for aging individuals and people with neurological disorders such as Parkinson disease (PD). Gait impairment characterized by reduced speed and higher variability destabilizes gait and increases the risk of falls. External auditory cueing provides an effective strategy to improve gait, as matching footfalls to rhythms typically increases gait speed and elicits larger steps, but the need to synchronize to an outside source often has a detrimental effect on gait variability. Internal cueing in the form of singing may provide an alternative to conventional gait therapy. In the present study, we compare the effects of internal and external cueing techniques on forward and backward walking for both people with PD and healthy controls. Results indicate that internal cueing was associated with improvements in gait velocity, cadence, and stride length in the backward direction, and reduced variability in both forward and backward walking. In comparison, external cueing was associated with minimal improvement in gait characteristics and a decline in gait stability. People with gait impairment due to aging or neurological decline may benefit more from internal cueing techniques such as singing as compared to external cueing techniques.

Modulation of individual auditory-motor coordination dynamics through interpersonal visual coupling

The current study investigated whether visual coupling between two people producing dance-related movements (requiring whole-body auditory-motor coordination) results in interpersonal entrainment and modulates individual auditory-motor coordination dynamics. Paired participants performed two kinds of coordination tasks – either knee flexion or extension repeatedly with metronome beats (Flexion-on-the-beat and Extension-on-the-beat conditions) while standing face-to-face or back-to-back to manipulate visual interaction. The results indicated that the relative phases between paired participants’ movements were closer to 0° and less variable when participants could see each other. In addition, visibility of the partner reduced individual differences in the dynamics of auditory-motor coordination by modulating coordination variability and the frequency of phase transitions from Extension-on-the-beat to Flexion-on-the-beat. Together, these results indicate that visual coupling takes place when paired participants can see each other and leads to interpersonal entrainment during rhythmic auditory-motor coordination, which compensates for individual differences via behavioural assimilation and thus enables individuals to achieve unified and cohesive performances.