by Hiroki Aoki, Shinichi Demura and Hiroshi Hirai
Original Research
This study examined how the amount of body sway various by age when people are standing on either a stable or an unstable surface with eyes either open or closed. The participants were 83 healthy women ranging in age from their teens to their eighties (with 9 to 12 women in each of the eight 10-year cohorts). Body sway was measured for 60 s while the participants were standing on a force plate with foam rubber (stable posture) or without form rubber (unstable posture). Path length (in cm), envelopment area (in cm2), and the ratio between these two measures were selected as evaluation parameters. In a three-way analysis of visual, posture, and age factors, path length, and envelopment area showed a significant interaction. Path length was shorter with the rubber than without it for all age levels with the eyes open or closed. An age-level difference was found only when the eyes were open. The envelopment area was smaller with than without the rubber with the eyes open for all age levels except women in their thirties and for all age groups with the eyes closed. Again, a significant age-level difference was found only with the eyes open. The ratio of length to envelopment area demonstrated a significant main effect for factors of both posture and age level. It was greater without than with the foam rubber with the eyes open for all age levels except women from their twenties to their forties, and for all age levels with the eyes closed. Coefficients in the linear regression equations, calculated based on the means for each age level, were significant in for three parameters. Values of path length and envelopment area were smaller without than with the rubber, but no significant differences were found between these values with the eyes open and closed. In conclusion, body sway in all age levels is greater on a less stable surface and increases with age, but the effect of vision on body sway can be disregarded.
American Journal of Sports Science and Medicine. 2018, 6(1), 33-38. DOI: 10.12691/ajssm-6-1-7
Pub. Date: March 06, 2018
11348 Views2802 Downloads1 Likes
by Hiroki Aoki, Shinichi Demura, Shunsuke Yamaji and Masashi Omoya
Original Research
This study aimed to examine the direction of errors between demand values and exerted forces using submaximal grip strength based on laterality. Subjects were 100 healthy young males (age: 22.4 ± 2.8 years). After maximum grip strength (MGS) was measured, each subject exerted handgrip for each demanded value (20%, 40%, 60%, and 80%), twice with a 2-min rest between each trial. The means of all subjects were used for statistical analysis. Evaluation parameters were errors between exertion and demand values, which are relative values based on MGS. The Shapiro-Wilk test was performed to confirm the normality of the frequency distribution. It was confirmed that errors in demand values, except for 80% in the dominant hand, show a normal distribution. The result of two-way repeated measures analysis of variance (ANOVA; demanded values × dominant/non-dominant) and multiple comparisons showed that significant differences were found among demand values, except between 60% and 80% in the dominant hand, and the error was greater as follows: 20% > 40% > 60% and 80%. The error in the non-dominant hand was greater in the order of 20%, 40%, 60%, and 80%. A significant difference was found between errors of the dominant and non-dominant hands in demand values of 20%–60%, and the error was smaller in the dominant hand. Test of independence for the frequency difference of exertion direction showed significant difference in all demand values except for 80%; 20% and 40% did more in the positive direction (overexertion) in both hands, and 60% did more in the negative direction (underexertion) in the dominant hand and in the plus direction in the non-dominant hand. In conclusion, in the dominant hand, the error of grip force exertion toward demand values is greater in demand values under 60% and small grip vales are exerted. In contrast, in the non-dominant hand，the error of grip force exertion toward demand values is greater in demand values under 80% and grip values are exerted largely in demand values under 60%. Accuracy of force exertion differs among demand values, and laterality is found in low demand values of 20%–60%.
American Journal of Sports Science and Medicine. 2018, 6(1), 28-32. DOI: 10.12691/ajssm-6-1-6
Pub. Date: March 06, 2018
9788 Views2847 Downloads
by Tamotsu Kitabayashi, Shinichi Demura and Hiroki Aoki
Original Research
This study aimed to examine body sway characteristics and to propose effective body sway parameters for healthy elderly. The subjects were 311 healthy elderly and 380 healthy young adults. None of the subjects had evidence or known history of gait, posture, or skeletal disorders. The center of foot pressure measurement for 1 min was performed in 1 trial Using Anima’s stabilometer G5500. The data sampling frequency was 20 Hz. Thirty parameters with high reliability were selected from 5 domains of distance, area, velocity, power spectrum, and body sway vector. In comparison with the results for young adults, the elderly had markedly larger values of mean path length and root mean square of x-axis, as well as for 5 velocity parameters and 4 vector velocity parameters. In addition, approximately 10% of the data for parameters related to body sway velocity, especially front/back body sway, even in the healthy elderly fell in an abnormal range of values (mean ± 3 SD). In conclusion, the following parameters may be useful to adequately and simply evaluate the body sway characteristics of the elderly: sway size, sway velocity, and from a directional viewpoint, sway size in the right/left direction and sway velocity in the front/back direction.
American Journal of Sports Science and Medicine. 2018, 6(1), 22-27. DOI: 10.12691/ajssm-6-1-5
Pub. Date: March 06, 2018
6411 Views2894 Downloads4 Likes
by Vinicius Monteiro Diederichs
Original Research
A novel approach significantly more effective both in ameliorating motor disabilities and in improving range of motion (ROM) of joints when compared with the current standard approach, proprioceptive neuromuscular facilitation (PNF). A total of 56 participants – of both genders, BMI normal, mean age 35 (range 21-68 years), exhibiting lumbopelvic extensor stiffness (assessed by performance of the deep squat test) - engaged in two experiments. Joint ROM was evaluated before and after treatment in each experiment. Participants were photographed performing the deep squat test and their joint ROM calculated with Kinovea software to obtain the data. In Experiment 1, twenty-six participants were randomly divided into two groups in order to compare the degree of improvement in ROM. One group was treated using the novel approach and the control group with PNF, both for three minutes duration. Results: statistically the effect size of the novel approach proved greater compared to the control PNF. In Experiment 2, thirty participants were treated only with the novel approach, motor disability being assessed with the Oswestry Disability Index (ODI) before and after five to seven days. Results: the novel approach proved significantly effective in ameliorating motor disabilities. Conclusion: the novel treatment is effective both in improving ROM of joints and in ameliorating motor disabilities. Moreover, in Experiment 2 the participants were assessed five to seven days after treatment, demonstrating that the improvement in ROM as well as the amelioration of motor disabilities is long lasting. Additionally, the degree of improvement in joint ROM observed in Experiment 1 finds confirmation in Experiment 2. Strikingly, after performance of the novel approach all the participants reported a pleasant sensation of lightness in walking - a phenomenon termed sensory attenuation, the term signifying the matching between sensory prediction and outcome.
American Journal of Sports Science and Medicine. 2018, 6(1), 15-21. DOI: 10.12691/ajssm-6-1-4
Pub. Date: January 29, 2018
13765 Views2935 Downloads2 Likes
by Hiroki Aoki, Shinichi Demura and Hiroshi Hirai
Original Research
Lower human limbs may not show laterality, differing from preferential use of upper limbs, because both legs are generally used at the same time. This study examined laterality of static and dynamic balance abilities during one-leg standing. The subjects were 100 healthy male university students (age 19.6 ± 2.4 years，height 172.3 ± 6.2 cm, weight 64.8 ± 8.5 kg). All subjects were judged right-leg dominant based on a previous survey. They underwent static and dynamic balance tests with each lower limb. A total path length during one-leg standing on a fixed stabilometer for the static balance test and an omnidirectional stability index during one-leg standing on an unstable platform (DYJOC Board) for the dynamic balance test was each used as an evaluation parameter. The mean of two trials was used as a representative value in each test. Intraclass correlation coefficients (ICCs) in both balance tests were very high (ICC = 0.75-0.91). A non-significant difference between means of dominant and non-dominant legs was found in both tests; their correlations were significant and high (0.93 and 0.75). In addition, a correlation between dynamic and static balance tests in both legs was found be significant but low (0.21-0.25). In conclusion, the laterality is not found in the static and dynamic balance abilities during one-leg standing evaluated by the tests selected in this study, and the relation between both abilities is negligible size.
American Journal of Sports Science and Medicine. 2018, 6(1), 11-14. DOI: 10.12691/ajssm-6-1-3
Pub. Date: January 29, 2018
8684 Views2407 Downloads2 Likes
by Arefayne Mesfen, Tewodros Abir and Alemayehu Ejigu
Original Research
The purpose of this research was to study the North Shewa Zone’s Debre Berhan town football team players alternative affecting variables that would enhance quality training by improving the performance of the team. The sample of the subject consists of 1 football coach and 25 players. To conduct this study both quantitative and qualitative method with descriptive survey design was employed. A variable data were suggested to create the function of quality training has a significant impact to play quality training in football. The result of the study indicates that some variables affect the performance of North Shewa zone Debre Berhan town football team. The respondents stated that lack of good communication among the concerned body, coaches’ low attention given for trainings, players’ low motivation for gaining new skill, coaches’ limited knowledge how to organize quality training, lack of supervision during training to know the level of performance and low attention given to team work were major variables.
American Journal of Sports Science and Medicine. 2018, 6(1), 5-10. DOI: 10.12691/ajssm-6-1-2
Pub. Date: January 05, 2018
5262 Views1643 Downloads
by Janel Bailey, Rachael Irving and Eon Campbell
Original Research
Changes in body composition parameters can be used as a mean of tracking an athlete’s health. Athletic performance relative to fat mass should be evaluated as an increase may be detrimental to physical activities by increasing energy demands and decreasing performance. Body composition, is an important indicator of nutritional status, water homeostasis and the specific adaptations to different physical training regimens. Similarly, assessment of the thigh muscles can provide adequate information on functionality and injury vulnerability. Knowledge garnered from biometric analysis using ultrasound and bio-impedance analysis technology, may be used to gauge the health status of future elite athletes. Assessing the body composition and muscle characteristics of young athletes, allow for early detection of weak areas that may negatively affect the performance of these athletes in the future. In addition, knowledge of how these parameters vary with performance provides an athlete with data that may be used to optimize performance.
American Journal of Sports Science and Medicine. 2018, 6(1), 1-4. DOI: 10.12691/ajssm-6-1-1
Pub. Date: December 29, 2017
7587 Views2179 Downloads2 Likes