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Saraslanidis P Petridou A Bogdanis GC Galanis N Tsalis G Kellis S Mougios V 《Journal of sports sciences》2011,29(11):1167-1174
Repeated-sprint training often involves short sprints separated by inadequate recovery intervals. The effects of interval duration on metabolic and performance parameters are unclear. We compared the effects of two training programmes, differing in rest interval duration, on muscle (vastus lateralis) metabolism and sprint performance. Sixteen men trained three times a week for 8 weeks, each training session comprising 2-3 sets of two 80-m sprints. Sprints were separated by 10 s (n = 8) or 1 min (n = 8). Both training programmes improved performance in the 100-, 200-, and 300-m sprints, but the improvement was greater in the 10-s group during the final 100 m of the 200- and 300-m runs. Independent of interval duration, training mitigated the drop of muscle ATP after two 80-m sprints. The drop in phosphocreatine and the increases in glucose-6-phosphate and fructose-6-phosphate after two 80-m sprints were greater in the 10-s group. In conclusion, training with a limited number of repeated short sprints (≤10 s) may be more effective in improving speed maintenance in 200- and 300-m runs when performed with a 1:1 rather than a 1:6 exercise-to-rest ratio. This may be due to a greater activation of glycolysis caused, in part, by the limited resynthesis of phosphocreatine during the very short rest interval. 相似文献
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Eleftherios Kellis Fotini Arambatzi Christos Papadopoulos 《Journal of sports sciences》2013,31(10):1045-1055
The purpose of this study was to examine the effects of external load on vertical ground reaction force, and linear and angular kinematics, during squats. Eight males aged 22.1?±?0.8 years performed maximal concentric squats using loads ranging from 7 to 70% of one-repetition maximum on a force plate while linear barbell velocity and the angular kinematics of the hip, knee and ankle were recorded. Maximum, average and angle-specific values were recorded. The ground reaction force ranged from 1.67?±?0.20 to 3.21?±?0.29 times body weight and increased significantly as external load increased (P?<?0.05). Bar linear velocity ranged from 0.54?±?0.11 to 2.50?±?0.50?m?·?s?1 and decreased significantly with increasing external load (P?<?0.05). Hip, knee and ankle angles at maximum ground reaction force were affected by external load (P?<?0.05). The force?–?barbell velocity curves were fitted using linear models with coefficients (r 2) ranging from 0.59 to 0.96. The results suggest that maximal force exertion during squat exercises is not achieved at the same position of the lower body as external load is increased. In contrast, joint velocity coordination does not change as load is increased. The force?–?velocity relationship was linear and independent from the set of data used for its determination. 相似文献
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Eleftherios Klerides 《欧洲教育》2014,46(1):12-33
The purpose of this article is twofold. At a narrative level, it seeks to expand the thematic coverage of recent scholarship on educational transfer to include the mobility of a specific paradigm of history teaching across borders in Europe. At a theoretical level, the article focuses on the borders of intergovernmental and nongovernmental organizations and explores ways in which what defines and demarcates such borders shapes the transfer of knowledge. 相似文献
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D. Papadopoulou P. Malliou N. Kofotolis S.P. Vlachopoulos E. Kellis 《International Journal of Disability, Development & Education》2017,64(1):76-87
The purpose of this study was to examine parental perceptions about Health Related Quality of Life (HRQoL) of typical education and special education students in Greece. The Pediatric Quality of Life Inventory (PedsQL) was administered to the parents of 251 children from typical schools, 46 students attending integration classes (IC) within a typical school and 97 students attending special education (segregated) schools. A two-way analysis of covariance indicated that, compared to their typically developing peers, children attending special education schools and IC were reported by their parents to have lower PedsQL scores. Compared to children attending special education schools, children attending IC showed no differences in all PedsQL domains but the emotional domain score (p < .05). Based on parents’ responses, further improvements in special education settings and environments in the Greek educational system might be necessary to improve the HRQOL of students with disabilities. 相似文献
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Abstract The purpose of the present study was to compare the three-dimensional kinematics of the lower extremities and ground reaction forces between the instep kick and the kick with the outside area of the foot (outstep kick) in pubertal soccer players. Ten pubertal soccer players performed consecutive kicking trials in random order after a two-step angled approach with the instep and the outstep portion of the foot. Three-dimensional data and ground reaction forces were measured during kicking. Paired t-tests indicated significantly higher (P < 0.05) ball speeds and ball/foot speed ratios for the instep kick compared with the outstep kick. Non-significant differences in angular and linear sagittal plane kinematic parameters, temporal characteristics, and ground reaction forces between the instep and outstep soccer kicks were observed (P > 0.05). In contrast, analysis of variance indicated that the outstep kick displayed higher hip internal rotation and abduction, knee internal rotation, and ankle inversion than the instep kick (P < 0.05). Our results suggest that the instep kick is more powerful than the outstep kick and that different types of kick require different types of skill training. 相似文献
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Athanasios Katis Eleftherios Kellis Adrian Lees 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):287-299
Soccer kicking training should be adjusted to the characteristics of the athletes. Therefore, examination of differences in kicking kinematics of females and pubertal players relative to males is worthwhile. The purpose of the study was to compare kicking kinematics and segmental sequence parameters between male, female, and pubertal players. Ten adult male, ten adult female, and ten male pubertal players participated in the study. Participants performed five consecutive kicking trials of a stationary ball, as powerful as they could. Analysis of variance showed significantly higher ball velocity, higher joint linear velocities for the knee and the hip, and higher angular velocities of the knee and the ankle for males compared to female and pubertal players (p < 0.05). Similarly, the peak joint velocity was achieved significantly closer to ball impact in males compared to other groups (p < 0.05). Males also showed a more plantarflexed ankle immediately before ball impact (p < 0.05). Females and pubertal players may benefit from skill training aiming to increase ankle plantarflexion and hip flexion prior to ball impact, and to adjust thigh and shank motion, such that the shank–foot segment travels through a higher range of motion and with a greater velocity. 相似文献
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Katis A Kellis E 《Sports biomechanics / International Society of Biomechanics in Sports》2011,10(1):35-45
Cutting in soccer is a common skill used to avoid the opponent's pressure but the potential effects of such a skill on instep kicking performance have not been previously investigated. The purpose of this study was to examine the differences in lower limb biomechanics between straight approach soccer kicks and kicks performed following a cutting maneuver task. Ten young amateur soccer players performed, in a random order, instep kicks after a two-step straight approach run and kicks after a double "faking" cutting maneuver task. The results showed that kicking after a cutting maneuver task displayed significantly lower ball speed values compared with the straight approach instep kicking (16.73 vs. 19.78 m/s, respectively; p < 0.05). Moreover, analysis of variance showed significant differences between the two kicking conditions in ankle, knee and hip joint displacements. The present study indicated that performing instep kicks after a double-cutting maneuver reduces ball and foot speed probably due to increasing joint frontal and transverse plane rotations. Improvements in the performance of the cutting maneuver task through training might result in better transfer of energy and speed to the kicking task thus permitting players to perform more powerful kicks under realistic game conditions. 相似文献
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