THE RELATIONSHIPS BETWEEN THROWING VELOCITY AND MOTOR ABILITY PARAMETERS OF THE HIGH-PERFORMANCE HANDBALL PLAYERS

Throwing is one of the basic skills in handball. Two main factors are of importance with regard to the efficiency of shots: accuracy and throwing velocity. The determinants of the ball velocity can be divided into three groups concerning: technique of motion, somatic features and motor ability. Although the technique of motion and the fitness level can be improved by the training process, morphological factors are, in the main part, genetically determined. Since changes in the throwing technique among highperformance players are very small, it was assumed as constant during training process. The aim of the research was to find out the relationships between the linear speed of the ball's flight during different kind of throwing in handball and basic motor ability parameters of players in order to improve the efficiency of training. Twelve highperformance handballers (Polish National Term) took part in the experiment. The average (+SD) values of the body mass, height and age amounted to 89.0+7.8 kg. 1.88 +0.05 m and 23.3 +2.5 years, respectively. The linear ball velocity was measured using a special photocell system during throwing on the spot, with cross-over step and with a jump upwards. Throwing velocity values were related to a maximal muscle strength indicator Mm was evaluated on the basis of the sum of muscle torques developed isometrically by ten main muscle groups: flexors and extensors of elbow, shoulder, knee and hip joints and flexors and extensors of trunk. A special torquemeter device (local make) was employed. The maximal and average mechanical power of the lower extremity and trunk was measured during CMJ performed on a force place (KISTLER).An on-line operating computer (IBM PC) was used to process the force signal. The force-velocity parameters of arm flexion and extension were measured using CES Ariel modified in its mechanical part. Handballers performed STh in the sitting position, propelling the bar of the Arm-Leg Station. The movement was similar to the last phase before the release of the ball during a real throw. Each subject executed 3 kinds of tests: maximal speed diagnostic, isokinetic exercises at angular velocities of 100, 300 and 500 deg/s and isotonic exercises at external torque of 10, 30 and 50 Nxm. Thirty-three parameters were chosen to further the analysis. Result distributions were tested using the Shapiro-Wilk test of normality. A Pearson's correlation matrix was calculated in order to reduce the number of parameters (p50.05). At the next stage, multiple regression analysis was used to estimate relations between tested parameters. Statistically significant contribution of muscle strength (trunk flexors, strength indicator) and maximal forearm speed to the ball velocity has been found

DETERMINANTS OF THE THROWING VELOCITY IN HANDBALL -A STATISTICAL MODEL

INTRODUCTION The aim of the research was to find the influence of the basic anthropometrical and motor ability parameters on the ball velocity during throws in handball. These relationships seem to be very important for coaches, in order to improve the selection quality and the efficiency of training methods. The last task is particularly difficult among experienced players. METHODS Twelve high-performance handball field players took part in the experiment. The following somatic anthropometric indices were used: length, skeleton width, musculature and adiposity (28 parameters for each player). The average linear ball velocity was measured using a special photocell system. Muscle strength was evaluated on a special stand (locally made) under static conditions (flexors and extensors of elbow, shoulder, knee and hip joints and trunk). The speed-strength characteristics of the upper extremity were measured on the modified CES Ariel. Subjects performed simulated throws in the sitting position. The maximal and average mechanical power of the lower extremity and trunk was measured during the vertical CMJ performed on a force platform. The mean value (SD) was calculated for each parameter. A normality of distributions was examined using the Shapiro-Wilk test. At the next stage Pearson's correlation matrix and a multiple regression analysis were used (pe0.05). The raw data was recalculated to values in the T-scale and according to the Doolittle method the contribution to throwing velocity was calculated. The best regression subset was assigned using Fisher's discriminating method. The regression hyperplane parameters were estimated. RESULTS Expected values of the ball velocity (R=0.982; R~=o9.6 3): Y = 0.018 XI + 0.733 X2 + 0.039 Xg -0.332 Xq + 0.006 Xg - 2.854 where: X1 - max. angular velocity of the bar (36%), X2 - range of fingers (41%), X3 - average mechanical power in CMJ (3%), Xq - shoulder width (6%), Xg - isometric muscle strength of trunk flexors (1 1 %). After recalculation to T-values the final equation contains two main factors: anthropometric (A) and motor (M): y=0.017 A + 0.072 M + 10.571 (R=O 857) The proportional contribution of these factors in expected value of the ball velocity is 11.9% and 61.4%, respectively. The hyperplane parameters, which divides subjects into two groups according to throwing velocity criterion, are as follows: 0.149 M + 0,051 A - 23.821 = 0 CONCLUSIONS These results suggest that the most important throwing velocity determinant is the motor abilities level. Among analyzed parameters the strength of trunk flexors (abdominal muscles) and maximal arm (shoulder joint) angular velocity have a decisive effect on the ball velocity in handball. REFERENCES Atwater A.B. (1980) Exer. Spod Sci. Rev. 7:43-85. Bartlett L.R., Storey M.D., Sirnons B.D. (1 989) Am. J. Sports Med. 1 7: 89-91 . Eliasz J., Janiak J., Wit A. (1990): Sporf Wyczynowy 911 0: 17-23. Joris ti., Muijen Van A.E., lngen Schenau Van G.J., Kemper H.C.G. (1 985) J. Biom. 18:409-414. Muijen Van A.E., Jiiris H., Kemper H.C.G., lngen Schenau Van G.J. (1991). Sports Training, Med. Rehab. 2: 103-1 13

AN ASSESSMENT OF SPEED-STRENGTH ABILITIES IN YOUNG MEN

INTRODUCTION Muscle strength is one of the most important factors in sport performance and other human activities -in this case it concerns the physical preparation of military pilots, particularly in order to develop the +Gz toleration. The study was designed to establish the parameters of speed-strength abilities of upper and lower extremities in young men. It allows us to find out the relationships between age, body mass, speed and muscle strength in order to improve the efficiency of weight training. METHODS One hundred young men (cadet-pilots) participated in the study. They were divided into two main groups: middle aviation school students (n=21; 16.0±1.1 years of age, 173.4±5.3 cm body height, 63.8±10.2 kg body weight) and the Polish Air-Force Academy students (n=79; 20.9±1.4 years of age, 178.0±5.7 cm b.h., 73.3±7.3 kg b.m.). In order to estimate the basic speed-strength parameters of upper and lower extremities both groups performed bench press and squats. Exercises were provided on a computerized stand (locally made) under isokinetic (co = 0.2 radIs) and isotonic (M = 20 Nxm) conditions. The subjects performed three trials with maximal effort to estimate the maximal speed (MS) and the maximal torque (MT) developed in the exercise. Descriptive statistics for each parameter as well as the t-test and Pearson's correlation matrix were used (

DETERMINANTS OF THE MAXIMAL MECHANICAL POWER DEVELOPED DURING THE COUNTERMOVEMENT JUMP (CMJ)

INTRODUCTION A countermovement (a preparatory movement in the direction opposite to that of the goal) increases performance in explosive movements such as the CMJ. The height of jump and the maximal power relative to body weight have been reported to be significantly correlated. Our previous observations has suggested the take-off technique (the countermovement depth) to affect power rather than height of jump. The purpose of the present study was to determine the influence of the height of jump, of the countermovement depth and of body mass on the maximal mechanical power developed during the positive take-off phase. METHODS Untrained students (56 female and 38 male) volunteered to take part in the CMJ jumping test consisting of 3 jumps performed with one-minute intervals on the computerized Kistler force plate. The subjects were requested to jump on the maximal height possible. Results of the highest jump were selected for each subject for further processing. The following variables were included into statistical analysis: the maximal mechanical power (PmaJ developed during the take-off, the height of jump (H), lowering of the body mass center before the take-off (L). and body mass (mb)' The Shapiro-Wilk test was used to examine the distributions of the tested variables. Pearson's correlation matrix and multiple regression analysis were employed to identity the parameters of the Pmax statistical model. Dolittle's method was used to estimate the contribution of the selected jump variables to the Pmax. RESULTS In both female and male groups the multiple regression procedure (the forward stepwise method) employed all the independent variables studied to construct the regressions equations. both of them proving very highly significant (

PROGRAMMED STRENGTH TRAINING USING A COMPUTERIZED ISOTONIC STAND

One of the very important tasks of the theory and practice of modern training is searching for new methods, in order to improve the efficiency of the training process. Nowadays muscle strength seems to be the most significant factor which influences performance in different kinds of sport. On the other hand development of the strength level is particularly difficult among highperformance athletes. The aim of this paper is to present computer-controlled strength training using a special stand for museie strength training and diagnostics. The stand consists of three main sub-assembles: -mechanical part (steel bedplate, bar with replaceable holders, bench for exercises). -hydraulic resistance module, -efectronic part (valve controller, AlC converter, PC 486/100). A special computer program allows force stabilization in the full range of motion (isotonic resistance) and registration of the basic parameters of movement. The computer-controlled training program includes three basic strength training methods: -repetition (50-80% RM, 4-8 series, 1020 reps); -maximal efforts (90-100% RM, 1-5 series, 1-3 reps); -speed-strength (40-45% RM, 4-8 series, 8-12 reps). Besides these methods the user could exercise according to his (or her) individual program. There are four main indices describing training loads, which can be controlled: resistance, number of series, number of reps and rest periods. Various popular exercises as: bench press, seated press, squats, both-or one-hand pulls, biceps curl. bent over row, etc. can be performed on the stand. The computer program enables registration of the force and displacement of the bar and on this base calculation maximal and mean values of several important parameters of the workout: mechanical power, velocity of the bar, work per rep(s). set(s) and unit(s). The initial resistance is established during the special trials, assessing the speedstrength abilities of the user, and changes of training loads are accomplished automatically, according to achieved results in these trials. The computer-controlled strength training performed on the isotonic stand is designed for both, beginners and highperformance athletes. The equipment can be used under field or laboratory conditions, because it is very safe, not noisy and not too large. REFERENCES Ariel G., Penny M., Saar D.. Selinger A. (1990): Computer-controlled strength training program for the U.S. National Women's Volleyball Team. COTO Research Center. Abstract form. Eliasz J. (1993): Trening sity mi~sniowej w pilee r~cznej (Strength training in handball) Sport Wyczynowy 9/10:21-28. Kannus P. (1994): Isokinetic evaluation of muscular performance: Implications for museie testing and rehabilitation. Int. Journal of Sports Medicine 15. Suppt. 1:S11-18. Kemp M. (1989): Strength training principles. Modem Athlete and Coach 27:11-12. Pauletto B. (1991): Strength training for coaches. Human Kinetics. Champaign IL. Zatsiorsky V.M. (1995): Science and Practice of Strength Training. Human Kinetics. Champaign IL

γ-Secretase inhibitor enhances antitumour effect of radiation in Notch-expressing lung cancer

BACKGROUND: Notch receptor has an important role in both development and cancer. We previously reported that inhibition of the Notch3 by γ-secretase inhibitor (GSI) induces apoptosis and suppresses tumour proliferation in non-small-cell lung cancer. Although radiation is reported to induce Notch activation, little is known about the relationship between radiation and Notch pathway. METHODS: We examined the effect of combining GSI and radiation at different dosing in three Notch expressing lung cancer cell lines. The cytotoxic effect of GSI and radiation was evaluated using MTT assay and clonogenic assay in vitro and xenograft models. Expressions of Notch pathway, mitogen-activated protein kinase (MAPK) pathway and Bcl-2 family proteins were investigated using western blot analysis. RESULTS: We discovered that the antitumour effect of combining GSI and radiation was dependent on treatment schedule. γ-Secretase inhibitor administration after radiation had the greatest growth inhibition of lung cancer in vitro and in vivo. We showed that the combination induced apoptosis of lung cancer cell lines through the regulation of MAPK and Bcl-2 family proteins. Furthermore, activation of Notch after radiation was ameliorated by GSI administration, suggesting that treatment with GSI prevents Notch-induced radiation resistance. CONCLUSION: Notch has an important role in lung cancer. Treatment with GSI after radiation can significantly enhance radiation-mediated tumour cytotoxicity