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1.
Ayako Higashihara Yasuharu Nagano Kazumasa Takahashi Toru Fukubayashi 《Journal of sports sciences》2015,33(13):1366-1375
This study aimed to investigate the effects of forward trunk lean on hamstring muscle kinematics during sprinting. Eight male sprinters performed maximal-effort sprints in two trunk positions: forward lean and upright. A three-dimensional musculoskeletal model was used to compute the musculotendon lengths and velocity of the biceps femoris long head, semitendinosus, and semimembranosus muscles during the sprinting gait cycle. The musculotendon lengths of all the three hamstring muscles at foot strike and toe-off were significantly greater during the forward trunk lean sprint than during the upright trunk sprint. In addition, a positive peak musculotendon lengthening velocity was observed in the biceps femoris long head and semimembranosus muscles during the late stance phase, and musculotendon lengths at that instant were significantly greater during the forward trunk lean sprint than during the upright trunk sprint. The present study provides significant evidence that a potential for hamstring muscle strain injury involving forward trunk lean sprinting would exist during the stance phase. The results also indicate that the biceps femoris long head and semimembranosus muscles are stretched during forward trunk lean sprinting while contracting eccentrically in the late stance phase; thus, the elongation load on these muscles could be increased. 相似文献
2.
We compared the reading development of 77 deaf and hard-of-hearing (DHH) Japanese children, aged 5–7 (40 females), with 139 of their hearing peers (74 females) in 2018. We assessed each group's phonological awareness (PA), grammar, vocabulary, and reading of hiragana (Japanese orthography children learn first). DHH children showed significant delays in grammar and vocabulary but only a slight delay in PA. Younger DHH children scored better than their hearing peers in reading. Although PA predicted reading for hearing children, reading predicted PA for DHH children. PA partially explained grammar skills for both groups. The results suggest educational intervention for reading acquisition should be based on not only general linguistic features but also each language's unique characteristics. 相似文献
3.
Two models of vulnerability to socioenvironmental risk were examined in 337 African American children (M = 7.8 years) recruited to overrepresent prenatal alcohol or cocaine exposure: The cumulative risk model predicted synergistic effects from exposure to multiple risk factors, and the fetal patterning of disease model predicted that prenatal insult will increase vulnerability to environmental risk. Four or more risks emerged as a threshold for poorer cognitive and behavioral outcome among the non‐substance‐exposed children, whereas substance‐exposed children showed greater vulnerability to lower levels of environmental risk. Cumulative risk was associated with increased delinquent and internalizing behaviors only for the substance‐exposed group. Results support the cumulative risk model for non‐substance‐exposed children and increased vulnerability to environmental risk among the substance‐exposed group. 相似文献
4.
Chie Takahashi 《Compare》2008,38(1):5-22
This paper examines the quality and development of relations between organisations and the ways in which these are informed by incidental learning experiences in two projects. The paper conceptualizes instances of inter‐organisational learning (IOL) applying theories such as principal‐agent, prisoners' dilemma and women's place in community development. The main results are (a) that IOL can be used to maintain and modify relations of control and dominance in partnership hierarchies; (b) that IOL serves as a spin‐off of horizontal relationships and can be increased or reduced in the competition between partners for resources and identity; and (c) that IOL at the community level, when delivering outsiders' intervention, can be promoted by involving local authorities and operating within the existing household hierarchy. The paper shows that the influential role of individuals, beyond organisational boundaries, becomes critical through social networks and the establishment of trust‐based relations and resistance to learning as consequences of personal conflict. However, structural constraints in the aid system, such as asymmetric access to resources, expertise, knowledge, status and networks, ultimately determine the quality of funding management schemes and the emergence of an environment that stimulates mutual individual learning, which in turn may lead to organisational learning and inter‐organisational learning. 相似文献
5.
Kazumi Masuda Nobuo Kikuhara Hideyuki Takahashi Kunio Yamanaka 《Journal of sports sciences》2013,31(10):851-858
Abstract The aim of the present study was to examine the relationships between muscle cross-sectional area (CSA) and muscular strength in terms of knee extension and flexion, hip extension and flexion, and hip abduction and adduction among well-trained soccer players. Fourteen university soccer players participated in the study, who had previously been divided into two groups based on ability (Group A: above-average ability; Group B: average ability). Maximal isokinetic and concentric muscular strength was measured in knee extension/flexion, hip extension/flexion and hip abduction/adduction using an isokinetic dynamometer at 1.57 and 4.19 rad·s?1 (3.14 rad·s?1) in both the dominant and non-dominant leg. The CSAs of the thigh, gluteus muscles and iliopsoas muscles were calculated based on magnetic resonance imaging. There was no significant difference between the two groups in muscle CSA and isokinetic strength. Although there were some statistically significant differences between the dominant and non-dominant leg in terms of CSA and strength (P<0.05–0.01), these were small and negligible. Apart from a non-significant relationship between the CSAs of the adductor muscles and hip adductor strength (r<0.26, n.s.), the CSA of the other muscle groups correlated with maximal isokinetic strength (r=0.38–0.64, P<0.05). These results suggest that no difference in muscle characteristics (in terms of muscle CSA and strength) was apparent among well-trained soccer players, even between the dominant and non-dominant leg. There is also a case that the anatomical function of a single (or group of) muscle(s) may not be reflected by the strength—CSA relationship depending on the movements (such as hip adduction-adductor muscle CSA). Thus, further studies are required to develop methods to assess neuromuscular function in relation to muscle morphology among soccer players. 相似文献
6.
Takashi Umeda Kazuhiro Suzukawa Ippei Takahashi Yousuke Yamamoto Masaru Tanabe Arata Kojima 《Journal of sports sciences》2013,31(9):897-904
Abstract To clarify the physical and mental fatigue caused by intense exercise and the relationship between the two types of fatigue, we examined changes in anthropometric and biochemical variables, neutrophil function, and the Profile of Mood States (POMS) questionnaire in 13 female university judoists attending a one-week training camp. Blood glucose, total cholesterol, haemoglobin, leukocyte count, IgG, and phagocytic activity all decreased after the training camp compared with baseline (P ≤ 0.046). Aspartate aminotransferase, lactate dehydrogenase, creatine kinase, and neutrophil oxidative burst activity increased after the training camp (P ≤ 0.007). Of the POMS scores, that for Fatigue increased after the training camp (P = 0.041) and that for Vigour decreased (P = 0.042). The changes in several POMS scores correlated with the changes in blood biochemical variables. In particular, the change in Total mood disturbance was negatively associated with changes in myogenic enzymes (P ≤ 0.032). Our results suggest that intense exercise during training camps for female judoists leads to the appearance and accumulation of mental and physical fatigue, which are related to each other. 相似文献
7.
Jessica Dym Bartlett Maryna Raskin Chie Kotake Kristen D. Nearing M. Ann Easterbrooks 《Child abuse & neglect》2014
To inform efforts to prevent child neglect, we investigated a wide range of risk factors that have been largely unexamined in relation to infant neglect, the most commonly occurring form of child maltreatment. Using an ecological model of child neglect, we assessed the influence of characteristics at the level of the child, the mother, the family, and broader childrearing contexts on adolescent mothers’ likelihood of being a perpetrator in a substantiated case of neglect against their firstborn infants (n = 383, M = 12 months). Several factors were associated with infant neglect by young mothers: median block income, low infant birth weight, maternal smoking, maternal childhood history of neglect and of positive care, intimate partner violence (IPV) perpetrated by either the mother or her partner, and maternal use of mental health services. In multivariate models, income, a maternal childhood history of positive care, IPV by either a mother or her partner, and mental health service usage made significant contributions to the odds that a mother neglected her infant. Our findings suggest that these factors have particular salience to policymakers’ and practitioners’ efforts to identify high risk families and to intervene during the earliest months of life to prevent child neglect. 相似文献
8.
Volianitis S Dawson EA Dalsgaard M Yoshiga C Clemmesen J Secher NH Olsen N Nielsen HB 《Journal of sports sciences》2012,30(2):149-153
Reduced hepatic lactate elimination initiates blood lactate accumulation during incremental exercise. In this study, we wished to determine whether renal lactate elimination contributes to the initiation of blood lactate accumulation. The renal arterial-to-venous (a-v) lactate difference was determined in nine men during sodium lactate infusion to enhance the evaluation (0.5 mol x L(-1) at 16 ± 1 mL x min(-1); mean ± s) both at rest and during cycling exercise (heart rate 139 ± 5 beats x min(-1)). The renal release of erythropoietin was used to detect kidney tissue ischaemia. At rest, the a-v O(2) (CaO(2)-CvO(2)) and lactate concentration differences were 0.8 ± 0.2 and 0.02 ± 0.02 mmol x L(-1), respectively. During exercise, arterial lactate and CaO(2)-CvO(2) increased to 7.1 ± 1.1 and 2.6 ± 0.8 mmol x L(-1), respectively (P < 0.05), indicating a -70% reduction of renal blood flow with no significant change in the renal venous erythropoietin concentration (0.8 ± 1.4 U x L(-1)). The a-v lactate concentration difference increased to 0.5 ± 0.8 mmol x L(-1), indicating similar lactate elimination as at rest. In conclusion, a -70% reduction in renal blood flow does not provoke critical renal ischaemia, and renal lactate elimination is maintained. Thus, kidney lactate elimination is unlikely to contribute to the initial blood lactate accumulation during progressive exercise. 相似文献
9.
Bilateral leg extension power and fat-free mass in young oarsmen 总被引：1，自引：0，他引：1
We evaluated the impact of bilateral leg extension power and fat-free mass on 2000 m rowing ergometer performance in 332 young oarsmen (age 21+/-2 years, height 1.76+/-0.05 m, body mass 62+/-6 kg; mean+/-s). The 2000 m rowing performance time was correlated with height (1.62-1.93 m; R2=0.23, P<0.001), body mass (53-95 kg; R2=0.53, P<0.001), fat-free mass (47-82 kg; R2=0.58, P<0.001) and bilateral leg extension power (1202-3302 W; R2=0.38, P<0.001). Multiple regression analysis selected fat-free mass and bilateral leg extension power as regressor variables. Fat-free mass explained 58% of the variability in rowing performance and the inclusion of bilateral leg extension power improved the power of prediction by 5%. The results suggest that rowing involves almost every muscle in the body and that bilateral leg extension power is very important during this activity. 相似文献
10.
The aim of the present study was to examine how the recovery of physiological functioning of the leg muscles after high-intensity eccentric exercise such as downhill running could be promoted by aqua exercise for a period until the damaged muscle had recovered almost completely. Ten male long-distance runners were divided equally into an aqua exercise group and a control group. From the first day (Day 0) to the fourth day (Day 3), the participants completed a questionnaire on muscle soreness, and serum creatine kinase activity, muscle power, flexibility, whole-body reaction time and muscle stiffness were measured. After measurements on Day 0, the participants performed downhill running (three 5 min runs with a 5 min rest interval at -10%, 335.7 +/- 6.1 m . min-1). The aqua exercise group performed walking, jogging and jumping in water on three successive days following the downhill running on Day 0 for 30 min each day. Muscle power was reduced on Day 1 in the control group (P < 0.05). Muscle soreness in the calf on Day 3 was greater in the control group than that in the aqua exercise group (P < 0.05). In the aqua exercise group, muscle stiffness in the calf was less than that in the control group over 4 days (time main effect: P < 0.05; group x time interaction: P < 0.05). We conclude that aqua exercise promoted physiological functioning of the muscles in the legs after high-intensity downhill running for a period until the damaged muscles had recovered almost completely. 相似文献