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Rating of Perceived Exertion in the First Repetition is Related to the Total Repetitions Performed in Elastic Bands Training

Juan C. Colado, Javier Gené-Morales, Pablo Jiménez-Martínez, Jorge Flandez, Ana María Ferri-Caruana, and Carlos Babiloni-Lopez

Several devices (e.g., linear transducers) have been used for predicting resistance training intensity. However, subjective scales, such as rating of perceived exertion (RPE), are proposed as reliable and easier-to-use tools for monitoring intensity during resistance training. Accordingly, different perceptive scales have been presented in previous research for monitoring intensity during resistance training with elastic bands. The aim was to assess the accuracy and reliability of RPE for quantifying the potential maximal repetitions that could be performed at a given RPE (from 2 to 8 of 10) obtained in the first repetition. For this purpose, 13 recreationally active participants (age: 26.33 [6.52] years, body mass index: 24.97 [5.08] kg/m2) were involved in two familiarization and two experimental sessions. In each session, participants randomly performed one set at each intensity of the first repetition from 2/10 to 8/10 until volitional failure in three different exercises (fly, military press, and push–press). An individual grip width of the elastic band was chosen in each set. The number of repetitions and heart rate were assessed. Significance level was set at p < .05. Repetitions decreased when intensity increased (p < .01) and heart rate was higher in the global exercise (i.e., push–press; p < .05), but nonsignificant differences between intensities were reported. The level of experience influenced the number of repetitions performed (p < .05). Intersession reliability was set from good to excellent (range: 0.64–0.91). Therefore, the RPE of the first repetition is a relevant and reliable parameter related to the total number of repetitions performed for each RPE value in trained participants enrolled in elastic bands resistance training.

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Proprioceptive Acuity Assessment in Multiple Directions Across Multiple Joints in the Upper Limb

Kai-Qi Zhang, Yan-Xia Li, Na Lv, Qiang Ma, Shu-Jun Zhang, Xi Zhao, Kai Wang, Li Li, and Lin Li

Proprioception is essential for precise movement as it helps the body transmit important data about its surroundings to the central nervous system for maintaining body posture and position. This study aimed to investigate the effect of direction and joint angle on upper limb proprioception. Thirty individuals (all males) completed a position reproduction activity in 13 directions and three joint angles. It was discovered that upper limb proprioception is dependent on joint angle, direction, and range of motion. The position reproduction error was found to be dependent on the direction, which had a significantly lower accuracy in the direction with a larger range of motion. In addition, upper limb repositioning errors increased at greater limb elevation angles. Our findings also showed that the joint angle did not significantly affect the absolute error of elbow flexion. With an increase in the elbow flexion, the increase of the gravitational moment of the upper arm and hand coupled with the increase of the muscle arm of the biceps brachii possibly causes slight changes in muscle length perceived by spindles or muscular force perceived by Golgi tendon organs.

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Immediate Effects of Real-Time Feedback During Overground Gait Performed Using Inertial Measurement Units on Gait Parameters in Healthy Young Participants: A Cross-Sectional Study

Takasuke Miyazaki, Yasufumi Takeshita, Daichi Shimose, Shogo Kakimoto, Sota Araki, Yuta Matsuzawa, Shobu Nakashima, Yuki Nakai, Masayuki Kawada, and Ryoji Kiyama

This cross-sectional study examined the immediate effects of four types of real-time feedback during overground gait performed using inertial measurement units on gait kinematics in healthy young participants. Twelve healthy young participants (mean age: 27.1 years) performed 60-s gait trials with each of the following real-time feedback: walking spontaneously (no feedback trial); increasing the ankle plantar-flexion angle during the late stance (ankle trial); increasing the leg extension angle, defined the location of the ankle joint relative to the hip joint in the sagittal plane, during late stance (leg trial); and increasing the knee flexion angle during the swing phase (knee trial). Tilt angles and accelerations of the pelvis and lower limb segments were measured using seven inertial measurement units pre- and postfeedback trials. The differences in gait parameters pre- and postfeedback according to the types of feedback were compared using one-factor repeated-measures analysis of variance, Friedman test, and post hoc test. Real-time feedback in the ankle trial increased gait speed, step length, and ankle plantar-flexion angle compared to the no feedback trial (p ≤ .001). Meanwhile, real-time feedback in the leg trial increased step length and hip extension angle compared to the no feedback trial (p ≤ .001) and showed a tendency to increase gait speed and leg extension angle. Real-time feedback using inertial measurement units increased gait speed immediately with specific changes in gait kinematics in healthy participants. This study might imply the possibility of clinical application for overground gait training, and further studies are needed to clarify the effectiveness for older people.

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Judokas Exhibit Short Response Latency Even to Non-Judo-Specific External Perturbation: Insights Into the Involuntary Postural Control Ability in Humans

Natsuki Sado, Norihisa Fujii, Eri Nonaka, and Terumitsu Miyazaki

Humans experience unanticipated external postural perturbations and recover their posture faster via involuntary responses than voluntary responses. Previous cross-sectional comparisons between athletes and untrained populations have suggested that daily motor experiences can lead to adaptations in the reflex system, but the temporal aspect of this adaptation has been unclear. Here we show that judokas have an earlier muscle activation response to even non-judo-specific external perturbations compared with an untrained population. The response latency to a backward push-and-release type postural perturbation was compared between male judokas (n = 7, career >13 years, ranging from world champions to prefectural competitors) and untrained nonjudokas (n = 7). Latency was defined as the instant of tibialis anterior muscle activity onset. Judokas exhibited shorter latency (20.6 ± 7.1 ms) than nonjudokas (28.3 ± 8.9 ms). The rank order of latency in judokas did not correlate with their competition performance. We suggest that daily training in responding to perturbations might improve some parts of the sensorimotor pathway relating to postural response latency, and that this excellence in involuntary response is independent of athletic performance. The findings provide a novel perspective for understanding postural control ability in humans.

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Balance Control in Individuals With Visual Impairment: A Systematic Review and Meta-Analysis

Hamed Zarei, Ali Asghar Norasteh, Lauren J. Lieberman, Michael W. Ertel, and Ali Brian

Background: Individuals with visual impairment have balance deficits; therefore, this systematic review aimed to provide comprehensive insights into the balance control of individuals with visual impairments when compared with individuals with full vision. Methods: Primary sources were obtained from eight databases including PubMed, LILACS, Science Direct, SCOPUS, CINAHL, PEDro, CENTRAL, and Web of Science. The search period covered years from inception to January 10, 2022. Results: A total of 20 studies with 29 trials with 1,280 participants were included in the systematic review. The results showed that individuals with sight had better static and dynamic balance than individuals with visual impairment (p = .001). However, individuals with visual impairment had significantly better static balance with visual perturbation and stronger static balance with visual and proprioception perturbation (p = .001). Furthermore, individuals with sight had better balance control than individuals with visual impairment who participated in sports (p = .001). Finally, individuals with visual impairment who participated in sports had better balance control than sedentary people with visual impairment (p = .001). Conclusion: Individuals with visual impairment have defects in both dynamic and static balance when compared to individuals with sight. In addition, balance improved with increasing age in individuals with visual impairment while balance control was dependent on the proprioception and vestibular systems. Also, individuals with sight had better balance than individuals with visual impairment who participated in sports and individuals with visual impairment who participated in sports compared with sedentary people with visual impairment.

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Volume 27 (2023): Issue 3 (Jul 2023)

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The Association of Age and Sex With Joint Angles and Coordination During Unanticipated Cutting in Soccer Players

Shawn M. Robbins, Yuri Lopes Lima, Harry Brown, Moreno Morelli, David J. Pearsall, Marco Bühler, and Anouk Lamontagne

Deficits in movement patterns during cutting while running might place soccer players at risk of injury. The objective was to compare joint angles and intersegment coordination between sexes and ages during an unanticipated side-step cutting task in soccer players. This cross-sectional study recruited 11 male (four adolescents and seven adults) and 10 female (six adolescents and four adults) soccer players. Three-dimensional motion capture was used to measure lower-extremity joint and segment angles as participants performed an unanticipated cutting task. Hierarchical linear models examined relationships between joint angle characteristics with age and sex. Continuous relative phase was used to quantify intersegment coordination amplitude and variability. These values were compared between age and sex groups using analysis of covariance. Adult males had greater hip flexion angle excursions than adolescent males, while adult females had smaller excursions than adolescent females (p = .011). Females had smaller changes in hip flexion angles (p = .045), greater hip adduction angles (p = .043), and greater ankle eversion angles (p = .009) than males. Adolescents had greater hip internal rotation (p = .044) and knee flexion (p = .033) angles than adults, but smaller changes in knee flexion angles at precontact compared with stance/foot off (p < .001). For intersegment coordination, females were more out-of-phase than males in the foot/shank segment in the sagittal plane. There were no differences in intersegment coordination variability between groups. Differences in joint motion during an unanticipated cutting task were present between age groups and sexes. Injury prevention programs or training programs may be able target specific deficits to lower injury risk and improve performance.

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Identifying Referent Control Variables Underlying Goal-Directed Arm Movements

Marie-Reine El-Hage, Alexandra Wendling, Mindy F. Levin, and Anatol G. Feldman

The referent control theory (RCT) for action and perception is an advanced formulation of the equilibrium-point hypothesis. The RCT suggests that rather than directly specifying the desired motor outcome, the nervous system controls action and perception indirectly by setting the values of parameters of physical and physiological laws. This is done independently of values of kinematic and kinetic variables including electromyographic patterns describing the motor outcome. One such parameter—the threshold muscle length, λ, at which motoneurons of a given muscle begin to be recruited, has been identified experimentally. In RCT, a similar parameter, the referent arm position, R, has been defined for multiple arm muscles as the threshold arm position at which arm muscles can be quiescent but activated depending on the deflection of the actual arm position, Q, from R. Changes in R result in reciprocal changes in the activity of opposing muscle groups. We advanced the explanatory power of RCT by combining the usual biomechanical descriptions of motor actions with the identification of the timing of R underlying arm movements made with reversals in three directions and to three different extents. We found that in all movements, periods of minimization of the activity of multiple muscles could be identified at ∼61%–86% of the reaching extent in each direction. These electromyographic minimization periods reflect the spatial coordinates at which the R and Q overlap during the production of movements with reversals. The findings support the concept of the production of arm movement by shifting R.

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Effects of Wearing Slippers While Obstacle Crossing in Healthy Young Adults: Strategy for Toe Clearance Enhancement and Prevention of Slipper Loss

Kento Tanaka, Yusuke Sekiguchi, Keita Honda, and Shin-ichi Izumi

Wearing loose footwear, such as slippers, poses a risk factor for tripping. Previous studies have examined obstacle crossing to find strategies to avoid tripping. However, the effect of wearing slippers on the likelihood of tripping remains unclear. Therefore, this study aimed to determine whether wearing slippers while level walking and obstacle crossing affects kinematic characteristics and muscle activity. Sixteen healthy, young adults performed two tasks (a) while wearing slippers and (b) while barefoot: (1) level walking and (2) crossing a 10-cm obstacle. Toe clearance, joint angles, muscle activity, and cocontraction were measured for both the leading and trailing lower limbs. In the slipper-wearing condition, knee flexion and hip flexion angles were significantly increased in the swing phase for the leading limb (p < .001 and p < .001, respectively) and trailing limb (p < .001 and p = .004, respectively) compared with the barefoot condition. Tibialis anterior activity (p = .01) and muscle cocontraction of the tibialis anterior and the medial head of the gastrocnemius (p = .047) were significantly increased in the swing phase of the trailing limb for the slipper-wearing condition compared with the barefoot condition in the obstacle crossing task. Wearing slippers increased knee and hip flexion angles, and muscle cocontraction of the tibialis anterior and medial head of gastrocnemius increased during obstacle crossing. The results revealed that obstacle crossing while wearing slippers would require foot fixation adjustment in addition to increased knee and hip flexion to avoid toe collision.

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Stimulus–Response Compatibility During Fighting Task Simulation: Influences of the Opponent’s Spatial Codes on the Accuracy and Response Time

Andreza Abreus de Moura, Leonardo José Mataruna-Dos-Santos, and Erick Francisco Quintas Conde

Manual Reaction Time measures have been widely used to study interactions between perceptual, cognitive, and motor functions. The Stimulus–Response Compatibility is a phenomenon characterized through faster Manual Reaction Times when stimuli and response locations coincide (correspondent condition) than when they are on different sides (noncorrespondent condition). The present study adapted a protocol to study if the Stimulus–Response Compatibility effect can be detected during a virtual combat simulation. Twenty-seven participants were instructed to defend themselves by clicking a key in order to block the presented punch. Videos of two fighters were used, granting two types of basic strokes: the back fist, a punch performed with the dorsal part of the fighter’s hand, starting at the opposite side to which it is directed; and the hook punch, performed with a clenched fist starting and finishing ipsilaterally. The Manual Reaction Times were different between the correspondent and noncorrespondent conditions, F(1, 26) = 9.925; p < .004; η2 = .276, with an Stimulus–Response Compatibility effect of 72 ms. Errors were also different, F(1, 26) = 23.199; p < .001; η2 = .472, between the correspondent (13%) and the noncorrespondent conditions (23%). The study concluded that spatial codes presented at the beginning of the punch movement perception substantially influenced the response execution.