牽引説に基づいたシンスプリントの生体力学的特徴

筑波大学 (University of Tsukuba)201

Smart exercise application to improve leg function and short-term memory through game- like lunge exercises: development and evaluation

The purpose of this study was to evaluate the functionality, accuracy, and usability of a novel smart exercise application (SEA). The functionality such as counting lunges, providing task-related auditory feedback, and testing short-term memory was examined while thirteen young adults (six men, age 25.4 ± 8.3 years) performed the lunge exercise with the SEA. The accuracy of logged motion data including angles and accelerations were also tested. Another twenty-five participants (11 men, age 23.2 ± 5.7 years) evaluated the usability of the SEA interest, motivation, convenience, and strength/cognitive benefit via a questionnaire. The SEA assessed the lunge motion correctly, provided auditory feedback, and tested users’ short-term memory as required. High correlations (r = 0.90 to 0.99) with low RMSE (4.85 ̊ for direction angle, 0.13 to 0.22 m/ s2 for acceleration) were observed between the sensor output and the reference output. Bland-Altman plot also showed a low discrepancy between each of the two measures. Most participants positively answered all questions about interest (60%), motivation (40%), convenience (80%), strength benefits (92%), and cognitive benefits (88%) of the SEA. The SEA demonstrated accurate kinematic assessment of accelerations and directions, assessed the lunge motion correctly, and created the appropriate auditory feedback on the short- term memory task. The high rate of positive responses suggested the potential of the application in future use

DELAYED RECOVERY OF KNEE EXTENSION TORQUE FOLLOWING MAXIMAL ECCENTRIC CONTRACTIONS MAY BE DUE TO CENTRAL FATIGUE

This study compared 1) The isometric strength, and 2) Peripheral and central fatigue assessed by resting twitch and voluntary activation, following maximal eccentric contractions of knee extensors in young men and women. Nine healthy participants performed 150 maximal eccentric contractions at 60 degls of the knee extensor muscles while on a dynamometer. Maximal voluntary isometric contractions (MVIC) were assessed before, immediately, 1 day, 2 days, and 14 days after the eccentric contractions. Electrical stimulation was applied over the skin of knee extensor muscles to elicit twitch torque responses during and immediately following each MVIC. The MVIC torque, rate of torque development (RTD), resting twitch torque (RT), voluntary activation (VA), and time to peak decreased from the baseline after the eccentric fatiguing contractions (P c 0.05). RT and time to peak increased and fully recovered after 1 day (P > 0.05; compared with baseline). However, MVIC, RTD, and VA increased during the recovery but did not fully recover after 14 days (P c 0.05; compared with baseline). These results suggest that the delayed recovery of toque production is mainly due to decrements in central nervous system

Cross-cultural adaptation, reliability, and validity of the Japanese version of the Cumberland ankle instability tool

Purpose To study validity and reliability of a Japanese version of the Cumberland Ankle Instability Tool and to determine the optimal cutoff score. Methods In this study, the questionnaire was cross-culturally adapted into Japanese. The psychometric properties tested in the Japanese version of the CAIT were measured for criteria validity, internal consistency and test–retest reliability in 111 collegiate soccer athletes. We also established the questionnaire cutoff score for discriminating between individuals with and without CAI. Results There was a significant correlation between the Japanese version of the CAIT and the Karlsson score (r = 0.604, p < 0.001). The questionnaire had a high internal consistency (Cronbach’s α = 0.833) and reliability [intraclass correlation coefficient (ICC) = 0.826, 95% confidence interval (CI): 0.732–0.888]. The optimal cutoff score was ≤25, which was consistent with previous reports. Conclusions The Japanese version of the CAIT has been shown to be a valid and reliable questionnaire for determining the presence of CAI. We expect that researchers and clinicians will use the Japanese version of the CAIT in Japan

Prediction of Decline in Global Cognitive Function Using Machine Learning with Feature Ranking of Gait and Physical Fitness Outcomes in Older Adults

Gait and physical fitness are related to cognitive function. A decrease in motor function and physical fitness can serve as an indicator of declining global cognitive function in older adults. This study aims to use machine learning (ML) to identify important features of gait and physical fitness to predict a decline in global cognitive function in older adults. A total of three hundred and six participants aged seventy-five years or older were included in the study, and their gait performance at various speeds and physical fitness were evaluated. Eight ML models were applied to data ranked by the p-value (LP) of linear regression and the importance gain (XI) of XGboost. Five optimal features were selected using elastic net on the LP data for men, and twenty optimal features were selected using support vector machine on the XI data for women. Thus, the important features for predicting a potential decline in global cognitive function in older adults were successfully identified herein. The proposed ML approach could inspire future studies on the early detection and prevention of cognitive function decline in older adults

Associating Gait Phase and Physical Fitness with Global Cognitive Function in the Aged

This study aimed to identify classifier variables by considering both gait and physical fitness for identifying adults aged over 75 years and global cognitive function declines in older adults. The participants included 735 adults aged 65&ndash;89 years who were asked to walk at three different speeds (slower, preferred, and faster) while wearing inertial measurement units embedded in shoe-type data loggers and to perform nine physical fitness tests. The variability in the stance phase as well as the strength, balance, and functional endurance showed a strong dependence on the age being over 75 years. The cognitive function was evaluated by the Mini-Mental State Examination; a longer stance phase at a slower walking speed and decreased grip strength and five times sit-to-stand were associated with cognitive function. These findings may be useful for determining the decline in physical performance of older adults. A longer stance phase and decreased grip strength and five times sit-to-stand may be factors that help distinguish declines in cognitive function from normal age-related declines

The effect of cold ambient temperatures on climbing-specific finger flexor performance

Different ambient temperatures are known to affect muscular performance based on the type of contraction. The effect of cold (10°C) and thermoneutral (TN) (24°C) ambient temperatures on finger flexor performance was examined in 12 rock climbers. After 30 min of seated rest in the designated temperature condition, participants completed maximal voluntary contractions (MVC) on a climbing-specific finger flexor assessment device equipped with a crimp grip hold. Participants then completed an intermittent fatiguing task until failure. The fatiguing task consisted of 10-s contractions at 40% MVC followed by a 3-s of rest. MVC recovery was assessed immediately, 5, 10, and 15 min post-task failure. Estimated muscle temperature and subjective thermal ratings were significantly lower throughout testing in the cold condition (P \u3c .001). Finger flexor MVC strength was similar between conditions at baseline and throughout recovery. Time to task failure was significantly longer (364 ± 135 vs. 251 ± 97 s, P = .003) and force time integral was greater (53,715 ± 19,988 vs. 40,243 ± 15,360 Ns, P = .001) during the cold condition. No significant differences were found between conditions for force variability or electromyography (EMG) at the start and end of the fatiguing task. However, the rate of increase in EMG for the TN condition was significantly faster (P = .03). These results suggest important implications for researchers when examining climbing performance, especially in outdoor settings where temperatures may vary from day to day. Inconsistencies in testing temperatures might significantly affect muscular endurance

Choline-based multi-ingredient supplementation can improve explosive strength during a fatiguing task

Various choline-based multi-ingredient supplementations (CMS) have been suggested in the current market, but the research is limited. The purpose of this study was to investigate the acute effect of a CMS on physical performance. Fourteen male college football players (20.4 ± 1.0 years) participated in a randomized double-blind crossover experiment separated by 7 days. Subjects were given a CMS or a placebo 60 min before physical performance testing measures, including maximum vertical jumps, maximum voluntary isometric contractions (MVIC), maximal voluntary concentric contractions (MVCC), and fatiguing contractions. Four MVICs and seven sets of two MVCCs at various loads (1 N·m to 60% MVIC torque) were performed with the knee extensor muscles while seated on a dynamometer before and after the fatiguing tasks. During the fatiguing tasks, 120 MVCCs (4 sets × 30 reps) were performed with a load equivalent to 20% MVIC. Twitch interpolation technique was used to assess muscle contractile properties and voluntary activation. No significant differences were seen at baseline between sessions for all testing measures including vertical jump height, strength, power, muscle contractile properties and voluntary activation. Rate of torque development and impulse was higher in supplemental session compared to control session throughout the fatiguing contractions (p = 0.018, p \u3c 0.001, respectively). Acute CMS can improve explosive strength by delaying the onset of fatigue