Jerzy Sadowski

EFFECTS OF UNILATERAL AND BILATERAL PLYOMETRIC TRAINING ON POWER AND JUMPING ABILITY IN WOMEN

Makaruk, H, Winchester, JB, Sadowski, J, Czaplicki, A, and Sacewicz, T. Effects of unilateral and bilateral plyometric training on power and jumping ability in women. J Strength Cond Res 25(12): 3311–3318, 2011—The purpose of this study was to examine the effects of unilateral and bilateral plyometric exercise on peak power and jumping performance during different stages of a 12-week training and detraining in women. Forty-nine untrained but physically active female college students were randomly assigned to 1 of 3 groups: unilateral plyometric group (n = 16), bilateral plyometric group (BLE; n = 18), and a control group (n = 15). Peak power and jumping ability were assessed by means of the alternate leg tests (10-second Wingate test and 5 alternate leg bounds), bilateral leg test (countermovement jump [CMJ]) and unilateral leg test (unilateral CMJ). Performance indicators were measured pretraining, midtraining, posttraining, and detraining. Differences between dependent variables were assessed with a 3 × 4 (group × time) repeated analysis of variance with Tukeys post hoc test applied where appropriate. Effect size was calculated to determine the magnitude of significant differences between the researched parameters. Only the unilateral plyometric training produced significant (p < 0.05) improvement in all tests from pretraining to midtraining, but there was no significant (p < 0.05) increase in performance indicators from midtraining to posttraining. The BLE group significantly (p < 0.05) improved in all tests from pretraining to posttraining and did not significantly (p > 0.05) decrease power and jumping ability in all tests during detraining. These results suggest that unilateral plyometric exercises produce power and jumping performance during a shorter period when compared to bilateral plyometric exercises but achieved performance gains last longer after bilateral plyometric training. Practitioners should consider the inclusion of both unilateral and bilateral modes of plyometric exercise to elicit rapid improvements and guard against detraining.

Success factors in elite WTF taekwondo competitors

Background The aim of the study was to identify selected success factors of elite Olympic taekwondo competitors in the context of medals that they have or have not won during Polish Senior Championships (PSCs). Material/Methods: Sixty-four elite male taekwondo competitors took part in the study. The competitors were divided into two groups on the basis of their achievements: PSC medallists and non-medallists. Factors determining sports success were modelled with the use of a general linear model (GLM). The procedure lasted until the minimum of the quality criterion, i.e., the Akaike information criterion (AIC), was reached. Results: Successful competitors (medallists) demonstrated significantly better technique, conditioning and flexibility parameters. Technical skills (e.g., strikes and side and roundhouse kicks), speed, dynamic strength and endurance were the factors that contributed to the achievement of excellent results in taekwondo. Conclusions: The research results revealed groups of success factors in taekwondo at a national level. Variables concerning kicks exerted the greatest influence on point scores (360° dollyo chagi montong – 41% and dollyo chagi – 31%).

THE EFFECTS OF SINGLE VERSUS REPEATED PLYOMETRICS ON LANDING BIOMECHANICS AND JUMPING PERFORMANCE IN MEN

The aim of this study was to examine the chronic effects of single and repeated jumps training on vertical landing force (VGRF) and jump height in untrained men. The VGRF and jump height were compared after a six-week plyometric training programme containing single and repeated jumps, together with two additional parameters: landing time (LT) and range of the knee flexion during landing (KF). Thirty-six untrained physical education students with a plyometric training background were randomly assigned to a single jump group (SJG, n =12), repeated jumps group (RJG, n =12), and control group (CON, n =12). The SJG performed only single jumps, the RJG executed repeated (consecutive) jumps, whereas the CON did not perform any exercises at all. A countermovement jump (CMJ), repeated countermovement jumps (RCMJ), and a drop jump (DJ) were tested before and after the training. Only the RJG showed a significantly reduced VGRF (p < 0.05) in all tests. Both plyometric groups significantly improved (p < 0.05) their jump height in all tests. The LT was significantly greater in the RJG, compared to the SJG, in all tests. The KF was also significantly (p < 0.05) greater in the RJG than in the SJG for CMJ and RCMJ. The results suggest that repeated jumps are beneficial for simultaneous landing force reduction and jumping performance enhancement.

Effectiveness of the Power Dry-Land Training Programmes in Youth Swimmers

Effectiveness of the Power Dry-Land Training Programmes in Youth Swimmers The aim of the study was to evaluate the effects of the dry-land power training on swimming force, swimming performance and strength in youth swimmers. Twenty six male swimmers, free from injuries and training regularly at least 6 times a week, were enrolled in the study and randomly assigned to one of two groups: experimental (n=14, mean age 14.0 ± 0.5 yrs, mean height 1.67±0.08 m and mean body mass 55.71 ±9.55 kg) and control (n=12, mean age 14.1 ± 0.5 yrs, mean height 1.61±0.11 m and mean body mass 49.07 ±8.25 kg). The experimental group took part in a combined swimming and dry-land power training. The control group took part in swimming training only. The training programmes in water included a dominant aerobic work in front crawl. In this research the experimental group tended to present slightly greater improvements in sprint performance. However, the stroke frequency insignificantly decreased (-4.30%, p>0.05) in the experimental group and increased (6.28%, p>0.05) in the control group. The distance per stroke insignificantly increased in the experimental group (5.98%, p>0.05) and insignificantly decreased in the control group (-5.36%, p>0.05). A significant improvement of tethered swimming force for the experimental group (9.64%, p<0.02) was found, whereas the increase was not statistically significant in the control group (2.86%, p>0.05). The main data cannot clearly state that power training allowed an enhancement in swimming performance, although a tendency to improve swimming performance in tethered swimming was noticed.

Success factors in male WTF taekwondo juniors

The most important success factors in sports include body build, conditioning, technical and tactical skills, mental abilities and the experience of a competitor [1]. Since WTF (World Taekwondo Federation) taekwondo was approved for the Sydney 2000 Olympic Games, it has been the subject of extensive research, where one of the areas of interest is the identification of success factors. Training effectiveness in sport is measured with the best possible performance (result) in the most important competitions. Therefore, many researchers have been interested in establishing success factors in taekwondo. The majority of studies have sought to determine correlations between different indicators and performance in taekwondo, including morphological [2-10], biomechanical [7; 11], conditioning, physiological and psychological indicators [6;8; 12-14] and indicators related to coordination [15]. The aforementioned researchers have found that taekwondo competitors with mesomorphic body build, high levels of speed, strength, endurance and flexibility, as well as shorter reaction times and proper technique have achieved excellent results. Rarely have several success factors in elite taekwondo competitors been analysed simultaneously (in terms of me dals they have or have not won at the highest levels of competition). In the above-mentioned studies, researchers focus ed entirely on single factors that were somatic or physiological. The aim of this study was to identify selected success factors of elite Olympic taekwondo competitors within the context of medals that they have or have not won during Polish Junior Championships (PJCs).

Speed of Reaction and Fighting Effectiveness in Elite Greco-Roman Wrestlers

The purpose of the study was to determine the changes in simple reaction time and to define correlations between simple reaction time and technical and tactical actions performed by elite Greco-Roman wrestlers during a match. Twenty Greco-Roman wrestlers (M age = 19.5 years, SD = 1.8) from the Wrestling Sports Centre in Radom participated in the study. Simple reaction time (including reaction time and movement time) before a match and after the first, the second, and the third round was analyzed. The wrestlers’ reaction time and movement time changed in the course of performance. Wrestlers with higher sports achievements demonstrated a smaller decrement in simple reaction time and performed more technical and tactical actions during a match. The strongest correlations were observed between both reaction time and movement time and the number of technical and tactical actions performed during the last round. Quick reaction was a significant factor in determining the match outcome, which is revealed at submaximal intensity of the effort during a match.

Benefits of Bandwidth Feedback in Learning a Complex Gymnastic Skill

The aim of this study was to examine the effects of two different frequencies of feedback during the process of learning a complex gymnastic skill, the round-off salto backward tucked. Thirty male acrobats participated in the study. They were randomly assigned to two groups: B - bandwidth feedback (n=15) or C - 100% feedback (n=15). Group B was provided with error information regarding the key elements of movement techniques only (bandwidth feedback). Our research demonstrates the advantage of augmented feedback information related to errors in the key elements. Information about errors in the key elements during learning a complex gymnastic skill prevents the gymnast from becoming overwhelmed, which promotes better motor control. These results provide support for the generalisation of bandwidth feedback principles to a complex task. Our research shows that the guidance hypothesis can also be tested in practical settings for a complex movement task.

Effects of Rhodiola rosea supplementation on mental performance, physical capacity, and oxidative stress biomarkers in healthy men

Purpose The objective of this study was to investigate the effects of chronic Rhodiola rosea (R. rosea) supplementation on mental and physical performance, as well as hormonal and oxidative stress biomarkers. Methods Twenty-six healthy male students received either R. rosea extract (600 mg/day; RR) or placebo (PL) in a randomized double-blind trial. Prior to supplementation (Term I) and following 4 weeks of supplementation (Term II), the students underwent psychomotor tests for simple and choice reaction time, included in the Vienna Test System. Also, the subjects performed VO2peak test. Blood samples were obtained before and after the test to measure the hormonal profile (cortisol, testosterone, and growth hormone), as well as the biomarkers of oxidative stress (lipid hydroperoxides, total antioxidant capacity, and superoxide dismutase) and muscle damage (creatine kinase). Results R. rosea ingestion shortened reaction time and total response time. Moreover, a greater relative increase in the number of correct responses was observed in RR group as compared to the PL group. No changes in endurance exercise capacity and hormonal profile were observed after R. rosea ingestion. R. rosea ingestion raised plasma total antioxidant capacity. It did not, however, affect other measured parameters. Conclusion Chronic R. rosea ingestion does not affect physical performance, but can improve the results of some psychomotor tests (simple and choice reaction time) in young, healthy, and physically active men. The improvements in mental performance, however, at least in our study, seem not to be related to changes in cortisol release or antioxidant activity of R. rosea extract. Thus, the specific mechanisms responsible for these effects still need to be elucidated.

THE EFFECTS OF SWIMMING AND DRY-LAND RESISTANCE TRAINING PROGRAMME ON NON-SWIMMERS

Abstract Introduction. The aim of the study was to estimate the influence of combined swimming and dry-land resistance training on swimming force, swimming performance and strength in non-swimmers. Material and methods. Thirty male non-swimmers took part in the research. They were randomly assigned to one of the two groups: experimental (n=17) and control (n=13). The experimental group took part in combined swimming and dry-land resistance training. The control group took part in swimming training only. The swimming and dry-land resistance training programme lasted twelve weeks (48 training sessions of swimming and 36 sessions of dry-land resistance training). Average training volume and intensity were the same for all swimmers throughout the study protocol. The training programme included dominant aerobic work in front crawl. Results. Dry-land resistance training applied in the experimental group significantly improved the upper body strength. In spite of the theory that dry-land strength training is probably not specific enough to improve the sprint swim performance, the experimental group tended to demonstrate greater improvement in sprint performance. The imitation of the underwater phase of shoulder work during front crawl provided by the ergometer can be a useful training method in non-swimmers.

Effects of Assisted and Traditional Drop Jumps on Jumping Performance

The purpose of the present study was to evaluate the effects of assisted and traditional drop jumps on fast stretch-shortening cycle exercises in collegiate athletes. Participants were selected into one of three groups: 1) the assisted drop jump (n=11); the traditional drop jump (n=11); and 3) the control (n=11). The assisted drop jump training involved drop jumps (DJs) with assistance of tubing, whereas the traditional DJ training was performed without any assistance. Prior to and at the completion of 5-week training programs, DJs from heights of both 30 (DJ30) and 60 cm (DJ60) were conducted to determine jump height, drop jump reactivity coefficient, contact time and peak ground reaction force. Both the assisted DJ and traditional DJ training programs resulted in significant (p< 0.05) improvement in jump height, DJ reactivity coefficient and decreased contact time for DJ30. Although both the assisted DJ and traditional DJ modes also increased jump height and DJ reactivity coefficient for DJ60, an enhancement of the assisted DJ training in DJ reactivity coefficient was significantly greater compared to the traditional DJ training. In addition, the assisted DJ mode allowed for a significant reduction of ground reaction force, while the traditional DJ did not change the ground reaction force. The results of this study support the inclusion of assisted DJ training into jumping sports like basketball, volleyball, and track and field jumps. Our results further suggest that incorporating assisted DJ training may be appropriate for highly trained adult athletes due to jumping performance improvement and impact landing forces reduction simultaneously.