THE RELATIONSHIP BETWEEN MAXIMAL STRENGTH, VERTICAL JUMP, ACCELERATION AND CHANGE OF DIRECTION PERFORMANCE

The goal of the present study was to explore the relationship between maximum strength, the vertical jump, acceleration and change of direction performance in healthy young male students. The sample of variables included the following variables: body mass (BM), one repetition maximum on the half-squat test (Squat 1RM), one repetition maximum normalized for body mass (Squat 1RM_rel), peak power during the concentric phase of countermovement jump (Ppeak CMJ), vertical jump height during CMJ (CMJ_H), time for the 20m sprint (20m Srint) and time for the agility T-Test (Agility T-Test). The relationship was tested with the Pearson Coefficient of linear correlation (r). The results showed significant correlation between body mass with Squat 1RM_rel and peak concentric power during CMJ (r=-.424, and r=.377, respectively). Peak concentric power during CMJ additionally has a significant correlation with the change of direction abilities, 20m sprint, and vertical jump height, (r=-.401; r=-.467; r=.656; p<0.05, respectively). Also, significant correlation was determined between the 20m Sprint and Agility T-Test (r=.443; r=-.570, respectively), and Agility T-Test vertical jump height (r=-.498).  The level of relationships between maximum strength, acceleration, COD and CMJ may be attributable to differences in the control and coordination of several muscle groups during execution of these tests

The Relationship between Body Alometry and Leg Muscle Mechanical Characteristics with Gait Transition Speeds of Human Locomotion

Ходање и трчање спадају у природне облике кретања и представљају две основне кретне активности човека. Најмања брзина при којој човек спонтано из ходања прелази у трчање назива се транзитна брзина (PTS). Данас се најчешће прави разлика између брзине при којој човек спонтано из ходања прелази у трчање (WRT) и брзине при којој човек из трчања прелази у ходање (RWT). Иако је феномен транзитне брзине и фактори који утичу и/или детерминишу тренутак транзиције био предмет бројних истраживања, тачан механизам одговоран за конверзију начина кретања из ходања у трчање и обрнуто и даље није у потпуности разјашњен. У налазима досадашњих истраживања постоји знатан број неконзистентности о значају и утицају телесних димензија и мишићних фактора на феномен транзитне брзине. Неки експерименти су показали да лонгитудиналне телесне димензије представљају главну детерминанту транзитне брзине, док друга истраживања показују потпуно другачије резултате и као најважнији фактор наводе трансферзалне телесне димензије. Такође, ни у једном досадашњем истраживању нису проучаване релације алометрије људског тела са транзитном брзином, нити релације механичких карактеристика мишића ногу и транзитне брзине. С тим у вези, постављено је више циљева истраживања који су се односили на испитивање релације алометрије тела и механичких карактеристика мишића ногу са транзитним брзинама. Конкретно, циљеви су били да се утврди: (1) повезаност лонгитудиналних, трансверзалних и циркуларних димензија тела са PTS; (2) повезаност телесних пропорција са PTS; (3) повезаност варијабли телесне композиције са PTS; (4) предиктивна моћ алометрије тела у детерминисању PTS; (5) повезаност јачине и снаге мишића екстензора и флексора у зглобовима кука, колена и скочног зглоба са WRT и RWT; (6) предиктивна моћ механичких карактеристика мишића екстензора и флексора доњих екстремитета у детерминисању WRT и RWT. На основу циљева истраживања, планирана су и реализована два експеримента: Експеримент 1 је имао за циљ да на великом узорку мушкараца, хетерогених по телесним димензијама испита релације алометрије тела и PTS, док је циљ Експеримента 2 био да се на узорку мушкараца хомогенизованих по одређеним телесним димензијама, испитају релације механичких карактеристика мишића ногу и брзина WRT и RWT...Walking and running represent the two basic, fundamental patterns of human locomotion. The lowest speed at which a man spontaneously switches from walking to running is called preferred transition speed (PTS). Today researchers usually differentiate between walk to run transition speed (WRT) and run to walk transition speed (RWT). Although the phenomenon of PTS and the factors that influence and/or determine the moment of transition was the subject of numerous studies, the exact mechanism responsible for the walk to run transition and vice versa is still not completely explained. There are a considerable number of inconsistencies regarding the importance and influence of body size and muscle factors in the phenomenon of gait transition speed, in the previous research findings. While some experiments reported that longitudinal body dimensions are the main factor of gait transtion speed, others revealed transfersal body dimensions as the most important factor. Also, none of the studies explored the relationships between human allometry and PTS, or the relation of mechanical characteristics of leg muscles and transition speeds. In this regard, we set several research objectives related to the examination of the relationship between human allometry and mechanical characteristics of the leg muscles with gait transition speeds. Specifically, the objectives were to determine: (1) the relationship between longitudinal, transversal and circular dimensions of the body and PTS; (2) the relationship between body proportions and PTS; (3) the relationship between body composition variables and PTS; (4) the predictive power of human allometry in determination of PTS; (5) The correlation between strength and power properties of hip, knee and ankle extensors and flexors with WRT and RWT; (6) the predictive power of the mechanical characteristics of the leg extensor and flexor muscles in determination of WRT and RWT. Based on the research objectives, we planned and realized two experiments: the aim of Experiment 1 was to examine the relationships between the human body allometry and PTS in the large sample of males with the heterogeneous physical dimensions, while the aim of Experiment 2 was to examine the relationship between leg muscles mechanical ix characteristics and WRT and RWT speeds, in the sample of men homogenized by certain anthropometric dimensions. In the first experiment, the sample comprised 59 male subjects, students of the Faculty of Sport and Physical Education (age 21.76 ± 1.93 years) heterogeneous in physical dimensions. On the first day of testing, we measured 15 anthropometric variables (seven longitudinal, six transversal and 2 circular) and body composition (7 original and 3 indexed variables), while in the second day we determined individual PTS using the standard increment protocol. Statistical analysis included Pearson correlation in order to assess the relationship between the PTS and other variables and Multivariate linear regression was performed to assess the association of the PTS and others variables together. PTS, calculated as the mean of WRT and RWT was 7.96 ± 0.38 km h-1. After scaling to body height, the highest correlations with PTS were recorded for variable lower leg length (r = -0.488), foot length (r = 0.418) and leg length (r = -0.410, p < 0.01). Body proportions showed higher correlations with the PTS in compare to individual anthropometric variables, and the highest correlation was observed between the proportion of the thigh length/lower leg length and PTS (r = 0.521, p < 0.01). The amount of body fat and percentage of body fat were the only body composition with low inverse correlation with PTS (r = -0.250, p < 0.05). Low correlation was observed between the right leg muscle mass scaled to body weight and PTS (r = 0.309, p < 0.05). Linear regression showed that 31% of the PTS variance can be explained by the variables lower leg length and foot length. Results of hierarchical regression showed that the 50.4% of the PTS variance can be explained through four body proportions. The main results of this experiment indicate that the proportions of the body are better PTS predictors in compare to the individual anthropometric variables. This means that body constitution, and especially the proportions between the leg segments and percent of the leg muscle mass, are more important PTS determinants than length of individual body segments. Altogether, subjects with longer thighs, smaller ratios between shoulder/bitrochanteric diameter and leg/foot length, and more lean muscle mass in the legs might need less effort for walking at higher speeds and might have higher PTS. The aim of the second experiment was to determine which leg muscle groups and their mechanical characteristics and WRT and RWT speeds, in the sample of men homogenized by certain anthropometric dimensions..

MAXIMAL MUSCULAR STRENGTH AS A PREDICTOR OF OPTIMUM DROP HEIGHT

The first goal of the study was to examine the relationship between maximum muscle strength and optimal drop height (DHopt), while the second goal was to examine the relationship between regression models for the prediction of DHopt and DHopt determined by variable H. A total of 30 respondents, students of the Faculty of Sport and Physical Education participated in the experiment. During the experiment, eight altitudes were randomized in the range of 0.12 to 0.82 m. The instruction was to achieve a higher jump, with a shorter duration of rebound. A positive statistically significant correlation between DHopt determined by prediction method with 1 RM / BW0.67 and MDS (p<0.05) was calculated. When computing the DHopt connection determined by the dialing method with the maximum muscle strength of the subjects, no statistically significant correlation was obtained, but there is a positive trend. Determined by the prediction method DHopt is (0.47±0.17 m) and using the regression model with 1 RM/BW0.67 (0.47±0.07 m) and with MDS (0.48±0.06 m). In order to explain high relationship between models, it should be noted that the muscles of knee joint have a more important role in motor tasks performed at higher intensity like during drop jump. With this in mind, DHopt in the jumping jump can be determined depending on the neuromuscular capacity to generate the maximum muscle strength of the knee of the knee in order to use the optimal intensity within the pliometric training

IMPACT OF BODY COMPOSITION AND VO2 MAX ON THE COMPETITIVE SUCCESS IN TOP-LEVEL HANDBALL PLAYERS

The purpose of the study was to determine the morphological and functional characteristics of 32 Serbian national U20 handball players (age 20.43±1.16y; training experience 8.12±1.89y) before European championship in Switzerland (2006) and to determinate their impact on competitive performance and outstanding success achieved. The results show that wing players differ from other players in morphological characteristics. Values for body height, weight, BMI, muscle mass and fat mass were significantly lower compared to the other playing positions. Extremely low values of maximal oxygen uptake (VO2 max) were measured in all players (ranged from 2.68 to 4.66 l×min-1). Pivots had the highest VO2 max in absolute values (3.76 l×min-1), and wing players in relative terms (40.83 ml×kg-1×min-1). Handball is characterized by high intensity intermittent play, followed by a number of walking breaks and quick substitutions. This makes possible to retain high playing intensity during whole match, because players can be given rest periods whenever needed. This will result in a high intensity game that does not necessarily require high VO2 max. Competitive success in modern top-level handball might be more reliant on optimal tactical preparation than on the body composition and VO2 max of an individual athlete

NBA Pre-Draft Combine is the weak predictor of rookie basketball player’s performance

The goal of the study was to assess the relationship between rookie player’s Pre-Draft Combine physical abilities and basketball performance in the first NBA season. In strictly homogenized sample of players (N = 58) who matched the inclusion criterion of average playing time and number games in the period 2012-2015, the results indicate that Pre-Draft Combine testing procedures show low to moderate correlations with only few observed basketball performance variables in the first NBA season. The highest correlation was found between upper body strength and number of rebounds (r = .403, p = .002) and blocked shots (r = .333, p = .011). Regression model of Combine performance explained 24.7% of basketball performance with three physical performance tests. Practical application might suggest that some parts of the Combine might be restructured in order to include some other tests more informative tests for the future player performance and player selection.The paper is a part of the project III47015, funded by the Ministry of Education, Science and Technological Development of the Republic of Serbia – Scientific Projects 2011 – 2019

The Relationship between Body Alometry and Leg Muscle Mechanical Characteristics with Gait Transition Speeds of Human Locomotion

Ходање и трчање спадају у природне облике кретања и представљају две основне кретне активности човека. Најмања брзина при којој човек спонтано из ходања прелази у трчање назива се транзитна брзина (PTS). Данас се најчешће прави разлика између брзине при којој човек спонтано из ходања прелази у трчање (WRT) и брзине при којој човек из трчања прелази у ходање (RWT). Иако је феномен транзитне брзине и фактори који утичу и/или детерминишу тренутак транзиције био предмет бројних истраживања, тачан механизам одговоран за конверзију начина кретања из ходања у трчање и обрнуто и даље није у потпуности разјашњен. У налазима досадашњих истраживања постоји знатан број неконзистентности о значају и утицају телесних димензија и мишићних фактора на феномен транзитне брзине. Неки експерименти су показали да лонгитудиналне телесне димензије представљају главну детерминанту транзитне брзине, док друга истраживања показују потпуно другачије резултате и као најважнији фактор наводе трансферзалне телесне димензије. Такође, ни у једном досадашњем истраживању нису проучаване релације алометрије људског тела са транзитном брзином, нити релације механичких карактеристика мишића ногу и транзитне брзине. С тим у вези, постављено је више циљева истраживања који су се односили на испитивање релације алометрије тела и механичких карактеристика мишића ногу са транзитним брзинама. Конкретно, циљеви су били да се утврди: (1) повезаност лонгитудиналних, трансверзалних и циркуларних димензија тела са PTS; (2) повезаност телесних пропорција са PTS; (3) повезаност варијабли телесне композиције са PTS; (4) предиктивна моћ алометрије тела у детерминисању PTS; (5) повезаност јачине и снаге мишића екстензора и флексора у зглобовима кука, колена и скочног зглоба са WRT и RWT; (6) предиктивна моћ механичких карактеристика мишића екстензора и флексора доњих екстремитета у детерминисању WRT и RWT. На основу циљева истраживања, планирана су и реализована два експеримента: Експеримент 1 је имао за циљ да на великом узорку мушкараца, хетерогених по телесним димензијама испита релације алометрије тела и PTS, док је циљ Експеримента 2 био да се на узорку мушкараца хомогенизованих по одређеним телесним димензијама, испитају релације механичких карактеристика мишића ногу и брзина WRT и RWT...Walking and running represent the two basic, fundamental patterns of human locomotion. The lowest speed at which a man spontaneously switches from walking to running is called preferred transition speed (PTS). Today researchers usually differentiate between walk to run transition speed (WRT) and run to walk transition speed (RWT). Although the phenomenon of PTS and the factors that influence and/or determine the moment of transition was the subject of numerous studies, the exact mechanism responsible for the walk to run transition and vice versa is still not completely explained. There are a considerable number of inconsistencies regarding the importance and influence of body size and muscle factors in the phenomenon of gait transition speed, in the previous research findings. While some experiments reported that longitudinal body dimensions are the main factor of gait transtion speed, others revealed transfersal body dimensions as the most important factor. Also, none of the studies explored the relationships between human allometry and PTS, or the relation of mechanical characteristics of leg muscles and transition speeds. In this regard, we set several research objectives related to the examination of the relationship between human allometry and mechanical characteristics of the leg muscles with gait transition speeds. Specifically, the objectives were to determine: (1) the relationship between longitudinal, transversal and circular dimensions of the body and PTS; (2) the relationship between body proportions and PTS; (3) the relationship between body composition variables and PTS; (4) the predictive power of human allometry in determination of PTS; (5) The correlation between strength and power properties of hip, knee and ankle extensors and flexors with WRT and RWT; (6) the predictive power of the mechanical characteristics of the leg extensor and flexor muscles in determination of WRT and RWT. Based on the research objectives, we planned and realized two experiments: the aim of Experiment 1 was to examine the relationships between the human body allometry and PTS in the large sample of males with the heterogeneous physical dimensions, while the aim of Experiment 2 was to examine the relationship between leg muscles mechanical ix characteristics and WRT and RWT speeds, in the sample of men homogenized by certain anthropometric dimensions. In the first experiment, the sample comprised 59 male subjects, students of the Faculty of Sport and Physical Education (age 21.76 ± 1.93 years) heterogeneous in physical dimensions. On the first day of testing, we measured 15 anthropometric variables (seven longitudinal, six transversal and 2 circular) and body composition (7 original and 3 indexed variables), while in the second day we determined individual PTS using the standard increment protocol. Statistical analysis included Pearson correlation in order to assess the relationship between the PTS and other variables and Multivariate linear regression was performed to assess the association of the PTS and others variables together. PTS, calculated as the mean of WRT and RWT was 7.96 ± 0.38 km h-1. After scaling to body height, the highest correlations with PTS were recorded for variable lower leg length (r = -0.488), foot length (r = 0.418) and leg length (r = -0.410, p < 0.01). Body proportions showed higher correlations with the PTS in compare to individual anthropometric variables, and the highest correlation was observed between the proportion of the thigh length/lower leg length and PTS (r = 0.521, p < 0.01). The amount of body fat and percentage of body fat were the only body composition with low inverse correlation with PTS (r = -0.250, p < 0.05). Low correlation was observed between the right leg muscle mass scaled to body weight and PTS (r = 0.309, p < 0.05). Linear regression showed that 31% of the PTS variance can be explained by the variables lower leg length and foot length. Results of hierarchical regression showed that the 50.4% of the PTS variance can be explained through four body proportions. The main results of this experiment indicate that the proportions of the body are better PTS predictors in compare to the individual anthropometric variables. This means that body constitution, and especially the proportions between the leg segments and percent of the leg muscle mass, are more important PTS determinants than length of individual body segments. Altogether, subjects with longer thighs, smaller ratios between shoulder/bitrochanteric diameter and leg/foot length, and more lean muscle mass in the legs might need less effort for walking at higher speeds and might have higher PTS. The aim of the second experiment was to determine which leg muscle groups and their mechanical characteristics and WRT and RWT speeds, in the sample of men homogenized by certain anthropometric dimensions..

Effects of resistance training on hypertrophy, strength and tensiomyography parameters of elbow flexors: Role of eccentric phase duration

The aim of the study was to compare the effects of two different training protocols, which differ in the duration of the eccentric phase, on the one-repetition maximum (1RM), thickness and contractile properties of elbow flexors. Twenty untrained college students were randomly divided into two experimental groups, based on the training tempo: FEG (Faster Eccentric Group: 1/0/1/0) and SEG (Slower Eccentric Group: 4/0/1/0). Training intervention was a biceps bending exercise, conducted twice a week for 7 weeks. The intensity (60–70% RM), sets (3–4) and rest intervals (120 s) were held constant, while repetitions were performed until it was not possible to maintain a set duration. In the initial and final measurements, 1RM, muscle thickness and tensiomyography parameters – contraction time (Tc) and radial deformation (Dm) – were evaluated. An ANCOVA model (using baseline outcomes as covariates) was applied to determine between-group differences at post-test, while Pearson’s product-moment correlation coefficient was used to investigate the relationship between absolute changes in muscle thickness and Dm. Muscle strength increase was greater for SEG than for FEG (6.0 ± 1.76 vs. 3.30 ± 2.26 kg, p < 0.01). In both groups muscle thickness increased equally (FEG: 3.24 ± 2.01 vs. SEG: 3.57 ± 1.17 mm, p < 0.01), while an overall reduction in Dm was observed (FEG: 1.99 ± 1.20 vs. SEG: 2.26 ± 1.03 mm, p < 0.01). Values of Tc remained unchanged. A significant negative relationship was observed between changes in muscle thickness and Dm (r = -0.763, Adj.R² = 0.560, p < 0.01). These results indicate that the duration of the eccentric phase has no effect on muscle hypertrophy in untrained subjects, but that slower eccentric movement significantly increases 1RM

Paired sample t-test results for the percentage of one repetition maximum and body weight of isometric and isotonic exercises.

Paired sample t-test results for the percentage of one repetition maximum and body weight of isometric and isotonic exercises.</p