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1
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Differences in Force-Velocity Characteristics of Upper and Lower Limbs of Male Kickboxers

100%
Nikolaïdis P., Fragkiadiakis G., Papadopoulos V., Karydis N.
Baltic Journal of Health and Physical Activity
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2011
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vol. 3
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issue 3
147-153
EN
Background: Despite the increasing popularity of kickboxing, few studies have been conducted with regard to the physiology or the biomechanics of this sport. The aim of the present study is to examine the ratios of mechanical characteristics between upper and lower limbs of male kickboxers.Material/Methods: Fourteen male Caucasians, all members of recreational sport clubs, aged 21.77 (5.19) yr [mean (standard deviation)], body height 1.78 (0.067) m, body mass 75.4 (8.9) kg, body fat 14 (5) % and somatotype 3.5-4.9-2.3, performed the Force-velocity (F-v) test for both upper and lower extremities. The F-v test included five supramaximal pedal sprints, each lasting 7 sec, against incremental braking force (20-60 N for upper limbs and 30-70 N for lower limbs), on modified arm-cranking and on a cycle ergometer (Ergomedics 874, Monark, Sweden).Results: Maximal anaerobic power, Pmax, of upper limbs was associated with Pmax of lower limbs (r = 0.81, P < 0.001) and their ratio was 0.464 (0.079). The respective values of correlation coefficients of the theoretical maximal force, F0, were r = 0.63 (P < 0.05) and 0.57 (0.133), and of velocity, v0, r = 0.44 (P = 0.12) and 0.829 (0.095).Conclusions: In spite of moderate correlations between upper and lower limbs' F0 and v0, a stronger relationship was found with regard to Pmax. Separate upper and lower extremities' power output measures would be useful in evaluating training programs and in understanding the importance of power output for kickboxing performance.
2
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Mechanical, Hormonal and Psychological Effects of a Non-Failure Short-Term Strength Training Program in Young Tennis Players

88%
Sarabia J. M., Fernandez-Fernandez J., Juan-Recio C., Hernández-Davó H., Urbán T., Moya M.
Journal of Human Kinetics
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2015
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vol. 45
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issue 1
81-91
EN
This study examined the effects of a 6-week non-failure strength training program in youth tennis players. Twenty tennis players (age: 15.0 ± 1 years, body height: 170.9 ± 5.1 cm, body mass: 63.3 ± 9.1 kg) were divided into experimental and control groups. Pre and post-tests included half squats, bench press, squat jumps, countermovementjumps and side-ball throws. Salivary cortisol samples were collected, and the Profile of Mood States questionnaire was used weekly during an anatomical adaptation period, a main training period and after a tapering week. The results showed that, after the main training period, the experimental group significantly improved (p<0.05) in mean and peak power output and in the total number of repetitions during the half-squat endurance test; mean force, power and velocity in the half-squat power output test; Profile of Mood States (in total mood disturbance between the last week of the mean training period and the tapering week); and in squat-jump and countermovement-jump height. Moreover, significant differences were found between the groups at the post-tests in the total number of repetitions, mean and peak power during the half-squat endurance test, mean velocity in the half-squat power output test, salivary cortisol concentration (baselines, first and third week of the mean training period) and in the Profile of Mood States (in fatigue subscale: first and third week of the mean training period). In conclusion, a non-failure strength training protocol improved lower-limb performance levels and produced a moderate psychophysiological impact in youth elite tennis players, suggesting that it is a suitable program to improve strength. Such training protocols do not increase the total training load of tennis players and may be recommended to improve strength.
3
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Jumping Abilities and Power-Velocity Relationship in Judo Athletes: Comparative Analysis Among Age Categories

88%
Buśko K.
Human Movement
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2015
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vol. 16
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issue 2
78-82
EN
Purpose. The aim of the study was to examine age differences in the maximal power and height of rise of the body mass centre measured in spike jump (SPJ) and counter-movement jump (CMJ), and power-velocity relationship of lower extremities between cadet and U23 age class judo athletes. Methods. Seven cadets (age 16.6 ± 0.7 years) and eight U23 age class (21.3 ± 1.4 years) Polish judoists took part in the study. The maximal power and height of jump were measured at SPJ and CMJ jumps. Power- velocity relations (P-v) were determined from 5 maximal cycle ergometer exercise bouts at increasing external loads equal to 2.5, 5.0, 7.5, 10.0 and 12.5% of body weight (BW). Results. Cadet judoists had a significantly smaller maximal power output (11.56 ± 1.21 W ・ kg-1) than U23 athletes (12.69 ± 0.67 W ・ kg-1). The optimal velocity was similar in both group (119.3 ± 16.0 rpm and 119.6 ± 15.5 rpm, respectively). Significant age differences were founded between the cadet and U23 athletes for power output at external load equal 12.5% BW. Cadet judoists generated insignificantly lower maximal power in CMJ and SPJ than U23 judo athletes with except of the absolute maximal power in SPJ. The age difference was observed in height of CMJ. Conclusions. Based on the characteristics of F-v curve we can see in which direction follow the effects of training. Application of CMJ and SPJ in jumping test allows to assess changes in neuromuscular coordination. The use of the both methods give better information to optimal training control.
4
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Age- and Sex-Related Differences in Force-Velocity Characteristics of Upper and Lower Limbs of Competitive Adolescent Swimmers

88%
Nikolaidis P.
Journal of Human Kinetics
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2012
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vol. 32
87-95
EN
While there is a direct relationship between maximal anaerobic power (Pmax) and swimming performance, the relationship between upper and lower limbs with regard to Pmax and force-velocity (F-v) characteristics is not clear. The aim of the present study was to examine the effect of age and sex on the ratios of mechanical characteristics between upper and lower extremities of adolescent swimmers. Seventeen girls (aged 14.7±1.8 yr) (mean±standard deviation) and 28 boys (14.6±1.4 yr), all members of competitive swimming clubs, performed a F-v test for both legs and arms. In legs, boys had higher values of Pmax (t43=2.4, p<0.05), Pmax expressed in relative to body mass values (rPmax, t43=3.4, p<0.01) and v0 (t43=4.3, p<0.001), while no differences were found for F0 (t43=1.0, p=0.31) and v0/F0 (t43=0.55, p=0.59). In arms, boys had higher values of Pmax (t43=3.2, p<0.01), rPmax (t43=3.9, p<0.001) and v0 (t43=3.4, p<0.01), while no differences were found for F0 (t43=1.9, p=0.06) and v0/F0 (t43=0.16, p=0.87). However, no sex difference was found with regard to the ratios of Pmax (t43=1.9, p=0.06), F0 (t43=1.2, p=0.23) and v0 (t43=1.3, p=0.20) between upper and lower extremities. There was direct relationship between age and Pmax of legs (r=0.64, p<0.01 in girls; r=0.43, p<0.05 in boys) and arms (r=0.56, p<0.05; r=0.57, p<0.01 respectively), while there was not any significant association between age and the ratios of mechanical characteristics of upper and lower limbs. These findings emphasize the need for separate evaluation of arms' and legs' force-velocity characteristics on a regular basis and the consideration of these measures in training design.
5
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A Physiological and Kinematic Comparison of two Different Lean Back Positions During Stationary Rowing on a Concept II Machine

75%
Bell G., Bennett J., Reynolds W., Syrotuik D., Gervais P.
Journal of Human Kinetics
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2013
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vol. 37
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issue 1
99-108
EN
This study compared two different body positions at the finish of a stroke during stationary rowing exercise on physiological and kinematic measurements. Nine male and five female rowers volunteered for the study: mean age (± SD), body height and body mass were 27 ±9 yrs, 180.5 ±12.3 cm and 81.2 ±14.2 kg. The two body positions at the finish were controlled at an upright posture or a novel greater lean back position. All subjects completed 3 different experimental trials on a Concept IID rowing machine at 3 different exercise intensities and comparisons were made between the lean back position at the same stroke rate and the same power output as the upright trial. Power output, heart rate, oxygen uptake, energy expenditure and % efficiency were higher (p<0.05) with the greater lean back position at the same stroke rate compared to all other conditions. Range of motion at the hip, ankle, and elbow and the handle velocity and distance moved were greater (p<0.05) with the lean back position. In conclusion, a greater lean back posture at the finish during stationary rowing produces a higher power output and improved efficiency at the same stroke rate but at an elevated physiological cost compared to a more upright position. Despite the higher energy expenditure, the relative gain in power output and efficiency with no negative kinematic changes suggests that a greater lean back position at the finish will enhance performance during stationary rowing exercise.
6
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Changes of Maximal Muscle Torque and Maximal Power Output of Lower Extremities in Male Judoists During Training

75%
Buśko K., Nowak A.
Human Movement
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2008
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vol. 9
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issue 2
111-115
EN
Purpose. The aim of the study was to follow changes of the maximal muscle torque and maximal power output of lower extremities in male judoists during pre-competition training (PCT). The original hypothesis assumed that different training loads would cause changes of the maximal muscle torque and maximal power output of legs in male judoists during pre-competition training, but not changes of the topography of the maximal muscle torque in all muscle groups. Basic procedures. The study sample consisted of five male judoists from the Polish National Team. Muscle torque measurements in static conditions were performed shortly before PCT (I), after the strength training mesocycle (II) and immediately after PCT (III). Ten muscle groups were examined: flexors and extensors of the trunk, shoulder, elbow, hip and knee. The maximal power output of legs was measured on a dynamometric platform during counter-movement jumps (CMJ) and bounce counter-movement jumps (BCMJ). Main findings. The sums of the muscle torque of both arms and the trunk were changed insignificantly during pre-competition training (PCT). The sum of muscle torque of the right and left lower extremities increased significantly between the measurements I and III. The muscle percent topography of muscle groups also showed significant changes. Maximal power output of lower extremities measured during CMJ decreased significantly, but increased during BCMJ. Conclusion. PCT caused changes of the maximal muscle torque of lower extremities, but the muscle topography of the muscle groups revealed significant changes, too. The maximal power output of lower extremities measured during CMJ decreased.
7
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The Effect of Sonication Parameters on the Thickness of the Produced MoS2 Nano-Flakes

75%
Taghavi N. S., Afzalzadeh R., Taghavi N. S., Afzalzadeh R.
Archives of Acoustics
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2021
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vol. 46
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issue 1
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