Nine-Axis Sensor for Athlete Physical Training Load Characteristics

In order to understand the characteristic data of athletes’ training load, a method based on nine-axis sensor was proposed. Twenty-seven male college athletes were tested twice with a time interval of more than 48 hours. In part 1, participants take the 1 Repetition Maximum (1RM) test. The results show that maximum strength is one of the basic factors to develop the output power of athletes. In the process of skeletal muscle contraction, the curve of speed, force, and power is closely related. When the external load is 10%∼70%, the average power increases with the increase in the average force, it increases with the decrease in the average speed, and at 70%1RM, the average power reaches the peak and then decreases at an inflection point. It is proved that the accurate weight ratio of strength training is the basis of winning athletes, the focus of high level physical coach, and the premise of scientific sports training.

Observing errors in a combination of error and correct models favors observational motor learning

Background Imitative learning is highly effective from infancy to old age; however, little is known about the effects of observing errors during imitative learning. This study aimed to examine how observing errors affected imitative learning performance to maximize its effect. Methods In the pre-training session, participants were instructed to pinch at a target force (8 N) with auditory feedback regarding generated force while they watched videos of someone pinching a sponge at the target force. In the pre-test, participants pinched at the target force and did not view a model or receive auditory feedback. In Experiment 1, in the main training session, participants imitated models while they watched videos of pinching at either the incorrect force (error-mixed condition) or target force (correct condition). Then, the exact force generated was measured without receiving auditory feedback or viewing a model. In Experiment 2, using the same procedures, newly recruited participants watched videos of pinching at incorrect forces (4 and 24 N) as the error condition and the correct force as the correct condition. Results In Experiment 1, the average force was closer to the target force in the error-mixed condition than in the correct condition. In Experiment 2, the average force in the correct condition was closer to the target force than in the error condition. Conclusion Our findings indicated that observing error actions combined with correct actions affected imitation motor learning positively as error actions contained information on things to avoid in the target action. It provides further information to enhance imitative learning in mixed conditions compared to that with correct action alone.

Reliability of the Hip Extension Lower Exercise as a Measure of Eccentric Hamstring Strength

Hamstring strain injury (HSI) is a very common lower-body injury in field sports, and eccentric (ECC) hamstring strength is a potential modifiable risk factor, therefore having reliable eccentric hamstring strength assessments is critical. The aim of this study was to access test–retest reliability of the hip extension lower (HEL) exercise as a measure of ECC hamstring strength and inter-limb asymmetries. Twelve male elite level soccer players (mean; age: 21.8 years; height: 180.4 cm; weight: 75.7 kg) volunteered to participate in this study. Participants were from the same soccer club, covered all playing positions, and had no current injury issues. Participants performed two familiarization sessions to acquaint themselves with the device and exercise protocol. During testing, each participant performed three repetitions with 60s intra-set recovery provided. Average and peak force (N) was recorded for both limbs. Testing sessions took place on the same day and time over a two-week pre-season period and followed a full recovery day. Intraclass Correlation Coefficient (ICC), Coefficient of Variation (CV%), Minimal Detectable Change (MDC) and Typical Error (TE) were used to assess reliability. The HEL showed excellent reliability for average force (N) in the left (ICC (95% CI) = 0.9 (0.7–0.97); TE = 14.1 N, CV% = 1.87; MDC = 39.06 N) and right (ICC (95% CI) = 0.91 (0.73–0.97); TE = 20.89 N, CV% = 3.26; MDC = 57.87 N) limb, and also excellent reliability for peak force in the left (ICC (95% CI) = 0.91 (0.71–0.97); TE = 13.55 N, CV% = 1.61; MDC = 57.87 N) and right (ICC (95% CI) = 0.9 (0.7–0.97); TE = 21.70 N, CV% = 3.31; MDC = 60.11 N) limb. This data suggests the HEL as a reliable measure of both ECC hamstring strength and inter-limb asymmetries. Practitioners should consider the HEL as a reliable choice for measuring and monitoring eccentric hamstring strength in their athletes.

KINETIC INDICATORS OF TRAINING METHODS AND SELECTION OF YOUNG ROWERS

Modern diagnostics in rowing enables more and more possibilities for recording, and comparing numerous stroke variables. At the same time, many coaches fall into the trap of strict respect for the prescribed norms, ratios, and temporarily results, which the athlete must achieve if he wants to stay in the world of competitive rowing. On the example of the comparison of rowing schools RC "Danubius" and RC "Partizan", descriptive indicators are on the side of RC "Danubius" at a time of 2000m, average force and average power. No significant differences were found in average force (sig = 0,167) between rowers of RC "Danubius" and RC "Partizan", while statistically significant differences were recorded in time at 2000m (sig = 0,036) and power (sig = 0,02) in favor of rowers of RC “Danubius”. On the other hand, a higher correlation of average force (-0,955) and power (-0,928) with time on 2000m was achieved by RC "Partizan" than RC "Danubius" (-0,931) and (-0,896). The correlation between the average force, and the average power within one team shows a higher correlation for RC “Partizan" (0,95) compared to RC "Danubius" (0,755). The obtained results are not enough for single rower or crew elimination from competition to recreational section in the process of too frequent and strict selection of rowers, considering different possible ways of building rowing techniques and numerous parasitic factors that may affect measured variables, specialy at the age under 14 and novice rowers in general.

Design and Control of an Adaptive Knee Joint Exoskeleton Mechanism with Buffering Function

A knee exoskeleton with an adaptive instantaneous rotation center and impact absorption is used for rehabilitation. Due to the human knee joint’s special physiological structure and motion characteristics, the exoskeleton mechanism needs to be designed for both static and dynamic aspects. Therefore, a novel knee exoskeleton mechanism was designed. To adapt to the rotation center of the knee joint, a mechanism with cross-configuration was designed according to the equivalent degree of freedom and the stiffness of the springs was calculated by its combination with gait motion, so that the average force of the human body was minimized. A dynamic model of the exoskeleton was established. To overcome the uncertainty in the parameters of the human and robotic limbs, an adaptive controller was designed and a Lyapunov stability analysis was conducted to verify the system. A simulation was conducted and experimental results show that the tracking error of the knee joint angle between the actual and desired trajectory was within the range of −1 to 1 degree and indicate the effectiveness of the controller.

Impact of a Neck Strap Intervention on Perceived Effort, Thumb Force, and Muscle Activity of Clarinetists

OBJECTIVE: Clarinetists often report discomfort of the right wrist and thumb and note that it is likely the result of the constant force applied to the area from the instrument’s weight and the musician’s technique. One preventative measure to reduce this discomfort is the use of a neck strap. The objective of the current study was to document the biomechanical impacts of this intervention. METHODS: Eight experienced clarinetists played a series of three etude pieces while playing both with and without a neck strap. For each condition, the force between the right thumb and clarinet was measured, electromyographic (EMG) data were collected from seven muscle groups, and subjective assessment of perceived effort was obtained. RESULTS: The results showed that when the neck strap was used, there was a significant decrease in the average force between the thumb and clarinet (p<0.05) and a decrease in the average perceived effort required for the right shoulder and thumb of the participants (p<0.05). Importantly, there were no statistically significant increases in the muscle activity of any of the neck and shoulder muscles with the introduction of the neck strap intervention. CONCLUSION: A neck strap intervention had positive effects on the right thumb while not causing any known adverse effects to other areas such as the neck, upper back, and shoulders.

Cantilever signature of tip detachment during contact resonance AFM

Contact resonance atomic force microscopy, piezoresponse force microscopy, and electrochemical strain microscopy are atomic force microscopy modes in which the cantilever is held in contact with the sample at a constant average force while monitoring the cantilever motion under the influence of a small, superimposed vibrational signal. Though these modes depend on permanent contact, there is a lack of detailed analysis on how the cantilever motion evolves when this essential condition is violated. This is not an uncommon occurrence since higher operating amplitudes tend to yield better signal-to-noise ratio, so users may inadvertently reduce their experimental accuracy by inducing tip–sample detachment in an effort to improve their measurements. We shed light on this issue by deliberately pushing both our experimental equipment and numerical simulations to the point of tip–sample detachment to explore cantilever dynamics during a useful and observable threshold feature in the measured response. Numerical simulations of the analytical model allow for extended insight into cantilever dynamics such as full-length deflection and slope behavior, which can be challenging or unobtainable in a standard equipment configuration. With such tools, we are able to determine the cantilever motion during detachment and connect the qualitative and quantitative behavior to experimental features.

Dynamics of special physical training of qualified MMA fighters during the preparatory period of the macrocycle when performing shock equipment

Purpose: to determine the influence of the experimental training program for qualified mixed martial arts fighters of 18-19 years old on their special physical fitness when performing shock actions. Material and methods. The study involved seven athletes 18-19 years old (all athletes - KMSU) department of mixed martial arts ODYUSSH «Dinamovets» in Zhitomir. A training program for qualified junior mixed martial arts fighters was developed using interval and interval-circular training methods with a wide range of general, special and competitive training means. The training program is designed for 15 weeks (may 17 - august 27, 2021) in the preparatory period of the macrocycle, therefore its predominant focus was towards physical fitness. Research methods: analysis of scientific theoretical sources, conversations with specialists, pedagogical observations, pedagogical testing, methods of mathematical statistics. Results: the dynamics of special physical readiness of qualified fighters was investigated, under the influence of an experimental training program, when performing percussion technique. The study of the dynamics of special physical readiness when performing a series of punches with hands showed significant positive shifts in the total force of punches with hands during the execution of an 8-second series (t=3,02; p˂0.05) and a 40-second series of punches (t=7,69; p˂0,001). The result of the average force of strikes (t=2,21; p˂0,05) in a 40-second series of strikes also noticeably improved. The study of the dynamics of special physical readiness when performing a series of strikes with the dominant leg revealed positive changes in the total force of strikes in the 8-second (t=3,33; p˂0,01) and 40-second (t=5,39; p˂0,001) tests. The high-speed component of the striking technique did not undergo significant positive changes, although there is a tendency towards positive dynamics (p>0,05). Conclusions. It was determined that the introduction of an experimental training program into the educational and training process of 18-19 year old mixed martial arts fighters made it possible to improve the special physical fitness of the fighters when performing specific striking techniques. In five studied indicators, a significant positive trend was obtained, confirmed by mathematical calculations. Significant positive changes in the total strength in the series of punches with the hands and the dominant leg were determined both in the 8-second and in the 40-second tests (p˂0,05 - p˂0,001). We also found a significant positive dynamics in the average force of punches in the 40-second test (p˂0,05). Keywords: mixed martial arts, qualified fighters, special physical training; interval training method; Interval-circular training method; training aids.

Design and analysis of linear switched reluctance motor

<p>This paper proposes a linear switched reluctance motor (LSRM) to replace the conventional serving that is used in food and beverage (F&amp;B) applications such as a pack of sushi and carbonated drinks. This conventional method is no longer practical as it requires a lot of space which will affect costing and productivity. It’s also has another disadvantage, in which it needs frequent maintenance of the rotational motor, gear, and limit switches. Therefore, this research is about the design and analysis of linear switched reluctance motor (LSRM) for F&amp;B applications. The main objective is to design a LSRM and the finite element method (FEM) is used to simulate the result. The result showed that the 24s/16p was the best model for linear switched reluctance motor (LSRM) design. The model had average force (F_avg) of 28.36 N for input current (I) of 1A. To conclude, this paper<br />provides a guideline in designing the LSRM for F&amp;B application.</p>

Electrospun bundled carbon nanofibers for skin-inspired tactile sensing, proprioception and gesture tracking applications

In this work, we report a class of wearable, stitchable, and sensitive carbon nanofiber (CNF)-polydimethylsiloxane (PDMS) composite-based piezoresistive sensors realized by carbonizing electrospun polyacrylonitrile (PAN) nanofibers and subsequently embedding in PDMS elastomeric thin films. Electro-mechanical tactile sensing characterization of the resulting piezoresistive strain sensors revealed a linear response with an average force sensitivity of ~1.82 kN−1 for normal forces up to 20 N. The real-time functionality of the CNF-PDMS composite sensors in wearable body sensor networks and advanced bionic skin applications was demonstrated through human motion and gesture monitoring experiments. A skin-inspired artificial soft sensor capable of demonstrating proprioceptive and tactile sensory perception utilizing CNF bundles has been shown. Furthermore, a 16-point pressure-sensitive flexible sensor array mimicking slow adapting low threshold mechanoreceptors of glabrous skin was demonstrated. Such devices in tandem with neuromorphic circuits can potentially recreate the sense of touch in robotic arms and restore somatosensory perception in amputees.