Fifteen young basketball players (aged 14.4 – 0.5 yrs) underwent two identical testing sessions spaced one week apart, to determine the reliability of maximum isometric force and force-time parameters during a maximal bilateral isometric leg press effort. The maximal isometric force (MIF), the ratio of maximal force to time (T MIF) to attain maximal force (ARMIF), starting strength (F 50), and on a relative scale the time taken to increase the force from 10% to 30%, 60%, and 90% of maximal force were calculated. High intraclass correlation coefficients (ICC) were found for MIF (0.96), ARMIF (0.85), and F50 (0.90). On the relative scale, the ICCs for the times to produce 30%, 60%, and 90% of maximum force were 0.94, 0.95, 0.95, respectively. The present results indicate that maximum isometric force and the force-time parameters during a bilateral leg press can be measured reliably in pubertal basketball players.
Panagiotis Ioakimidis, Vasilios Gerodimos, Eleftherios Kellis and Spiros Kellis
Eleftherios Kellis, Spiros Kellis, Vasilios Gerodimos and Vasiliki Manou
The reliable examination of isokinetic parameters in young athletes is important for the establishment of appropriate strength testing protocols. The purpose of this study was to examine the reliability of peak moments, non-preferred/preferred leg and reciprocal ratios during isokinetic knee efforts in young soccer players. Thirteen circumpubertal (age = 13.0 ± 0.4 years) soccer players performed maximum knee extension and flexion efforts at 30, 120 and 180°·s1 in two occasions, a week apart. The reliability of the peak moments was high, with reliability coefficients ranging from 0.71 to 0.98. The non-preferred/preferred leg and reciprocal ratios demonstrated moderate to high reliability (coefficients ranged from 0.42 to 0.87). The reliable examination of moments of force and ratio measurements during eccentric tests and at fast angular velocities in young soccer players requires extensive familiarization of the subjects prior to the main test.
Paraskevi Giagazoglou, Athanasios Katis, Eleftherios Kellis and Christos Natsikas
The purpose of the current study was to examine the kinematic differences during instep soccer kicks between players who were blind and sighted controls. Eleven male soccer players who were blind and nine male sighted performed instep kicks under static and dynamic conditions. The results indicated significantly higher (p < .05) ball speed velocities (20.81m/sec) and ball/foot speed ratio values (1.35) for soccer players who were blind during the static kick compared with sighted players (16.16m/sec and 1.23, respectively). Significant group effect on shank and foot angular velocity was observed during the static kicking condition (p < .05), while no differences were found during the dynamic kicking condition (p > .05). Despite the absence of vision, systematic training could have beneficial effects on technical skills, allowing athletes who are blind to develop skill levels comparable to sighted athletes.
Theodoros Kannas, Eleftherios Kellis, Fotini Arampatzi and Eduardo Saez Saez de Villarreal
The aim of this study was to examine the differences in muscle architecture during isometric tests between children and adults. Eight boys (age= 11.2 ± 0.26 years) and eight men (age= 22.3 ± 2.01 years) performed plantar flexion isometric efforts at angles of -15°, 0°, 15° at 0%, 40%, 60%, 80% of MVC. Analysis of variance tests indicated that adults showed greater fascicle length from rest to 80% of MVC (p < .05), greater pennation angle at 80% and 100% of MVC (p < .05) and greater aponeuroses displacement at levels of effort greater than 60% of MVC (p < .05). These differences observed in MG would appear to favor better utilization of the force-length and the force-velocity relationships, of the muscle in adults compared with children.
Maria Moussouli, Symeon P. Vlachopoulos, Nikolaos D. Kofotolis, Yannis Theodorakis, Paraskevi Malliou and Eleftherios Kellis
The study examined the effects of a 4-week intensive isometric and isotonic stabilization exercise program on dimensions of health-related quality of life (HRQL) in women with chronic low back pain (CLBP).
A total of 39 women (27–72 years old) provided data in an experimental study with a 9-month follow-up. Random allocation was undertaken for the two treatment groups out of the 3 groups: isometric stabilization (n = 13), isotonic stabilization (n = 13), and a control group (n = 13) that did not participate in any form of exercise. Health-related quality of life measures using the Short-Form 36 Health Survey were assessed before program initiation, immediately after program termination, and 4 times postintervention for a period of 9 months.
The isometric stabilization group displayed large improvements in bodily pain and vitality for women with CLBP attending a 4-week intensive isometric stabilization exercise program. The effects were retained for a period of 9 months after program termination.
Isometric stabilization exercises reduce pain and enhance vitality as dimensions of HRQL among women with chronic low back pain with such effects lasting for at least 9 months.