Agility Run Research Articles

Effect of Three Protocols of Warming up Involving Stretching on the Kinematic Performance of Horizontal Jumping, Agility and Speed for Soccer Players

The aim of this study is to investigate the effect of three different protocols of stretching on the kinematic performance of horizontal jumping, Agility and speed for soccer players. The first protocol is doing ballistic stretching then static stretching exercises (BS-SS). The second protocol is doing static stretching then ballistic stretching exercises (SS-BS). The third protocol is doing soccer passing drills (SPD) for 10 minutes without stretching. The three protocols were applied after 5 minutes of running activities. Dependent variables included a horizontal jump, agility run, and 30-m sprint tests. Also speed, acceleration, and steps frequency were analyzed. This study was applied on 23 trained male student-athletes aged (20+ 0.4 years). The (SS-BS) condition (2.247 + 0.096 m) showed significant differences (p < 0.01) for longer distance than the (BS-SS) condition (2.165 + 0.124) and also than the (SPD) condition (2.197 + 0.110 m) in the horizontal jump test. The (SS-BS) condition (3.544 + 0.247 second) also showed significant differences (p < 0.01) in the flying 30m sprint test for faster times than the (BS-SS) condition (3.858 + 0.288 second) and also than the third condition (SPD) (4.050 + 0.193 second) . The (SPD) condition showed significant differences (p < 0.01) in agility test for faster time than both the (BS-SS) (11.533 + 0.485) and (SS-BS) (11.676 + 0.530) conditions. Depending on the study results and previous studies, (SS-BS) which may be practiced before high intensity activities in trained athletes if preceded by moderate intensity running activities is recommended.

A new injury prevention programme for children’s football – FIFA 11+ Kids – can improve motor performance: a cluster-randomised controlled trial

ABSTRACTThe present study evaluated the effects of a newly developed injury prevention programme for children’s football (“FIFA 11+ Kids”) on motor performance in 7–12-year-old children. We stratified 12 football teams (under-9/-11/-13 age categories) into intervention (INT, N = 56 players) and control groups (CON, N = 67). INT conducted the 15-min warm-up programme “FIFA 11+ Kids” twice a week for 10 weeks. CON followed a standard warm-up (sham treatment). Pre- and post-tests were conducted using: single leg stance; Y-balance test; drop and countermovement jump; standing long jump; 20-m sprint; agility run; slalom dribble; and wall volley test. We used magnitude-based inferences and linear mixed-effects models to analyse performance test results. We observed likely beneficial effects favouring INT in Y-balance (right leg; +3.2%; standardised mean difference (SMD) = 0.34; P = 0.58) and agility run (+3.6%; SMD = 0.45; P = 0.008). Possibly beneficial effects were found in Y-balance, drop jump reactive strength index, drop jump height, countermovement jump, standing long jump, slalom dribble and wall volley test. At least possibly beneficial improvements in favour of “FIFA 11+ Kids” were observed in nearly all parameters. Most effects were small, but slight improvements in motor performance may potentially contribute to a reduction of injury risk.

Risk Factors for Injuries in Professional Football Players.

The aim of this study was to identify risk factors related to the occurrence of injuries in football players. The study included 216 football players from 12 teams in the elite football league. Football-related injury data were collected prospectively during the 2012/2013 competitive season. At baseline the following information was collected for the players: anthropometric measurements (weight, height, BMI, subcutaneous skinfolds), playing experience, injury history, physical fitness performance test (agility run), peak oxygen uptake. The incidence, type and severity of injuries and training and game exposure times were prospectively documented for each player. Most of the players (n = 155, 71.7%) sustained the injures during the study period. The overall injury incidence during the regular season was 6.3 injuries per 1000 athlete-exposures (95% confidence interval, 4.31-9.67). Multivariate logistic regression analysis showed that playing experience (odds ratio [OR] = 0.44; 95% CI = 0.32-0.61, p < 0.01), age (OR = 2.05; 95% CI = 1.49-2.81, p < 0.01) and a previous injury (OR = 4.4; 95% CI = 2.14-9.07, p < 0.01) were significantly correlated to increased risk of injuries. Body mass index was not associated with risk of injury. Strains (34.19%) and sprains (25.81%) were the major injury types. Twenty-seven percent of injured players were absent from football for more than 1 month, with knee injuries (25.42%) being the most severe type. The risk factors that increase injury rates in football players were previous injury, higher age and years of playing. Future research should include adequate rehabilitation program to reduce the risk of injuries.

Inertial Sensor and Cluster Analysis for Discriminating Agility Run Technique

Performance in an agility run drill is often used to characterize an athlete's ability to quickly and explosively change direction. Beyond athletic applications, agility tasks are also used to assess the physical readiness of warfighters for battle and the influence that their equipment has on their performance. However, in all of these applications, performance is currently assessed solely by reporting the time it takes to complete the drill. While completion time quite meaningfully discriminates bottom-line performance, it does not reveal the underlying biomechanics that contributes to or limits that performance. Biomechanical metrics that accurately identify performance strengths and weaknesses could promote rapid performance gains via tailored training programs and inform equipment design improvements. To these ends, we propose using a belt-worn wireless inertial measurement unit (IMU) to quantify the biomechanical metrics underlying speed and agility performance in agility assessment tasks. Herein, we describe a drift correction methodology that enables estimates of displacement, velocity, and acceleration of a subject's sacrum provided a course with known waypoints. We demonstrate the utility of this methodology through analysis of a large data set collected from 32 subjects completing a slalom run. A k-means cluster analysis of proposed performance metrics reveals two distinct groups of subjects who use fundamentally different techniques to negotiate the turns of the course. We believe that this measurement methodology can be used widely for agility assessment to provide athletes, trainers and researchers with actionable data to inform training plans and equipment modifications.

When the going gets tough: Mental toughness and its relationship with behavioural perseverance.

This study examined the association between self-reported mental toughness and behavioural perseverance among a sample of male Australian footballers in a naturalistic context. Cross-sectional field study, with the multistage 20m shuttle run test (MST) employed as a proxy for behavioural perseverance. 330 male Australian footballers aged between 15 and 18 years (M=16.86; SD=.71) with between 2 and 14 years playing experience (M=9.32; SD=2.51) participated. Initially, footballers completed a mental toughness questionnaire, before having their height and body mass measurements taken. Subsequently, a performance testing session was completed, which included the 20m sprint, Australian football-specific agility run, vertical jump, and the MST. Bayesian estimation was employed to allow for the simultaneous examination of existing findings with our new data in a way that provides an automatic meta-analysis of evidence in this area. The analysis indicated a 95% probability that the association between mental toughness and behavioural perseverance lies between .14 and .34, even when controlling for other factors known to influence MST performance, including age, height, body mass, and years playing experience. Taken together with previous research, these findings support the theoretical proposition that persistence, effort or perseverance represents a behavioural signature of mental toughness.

MEMS two-axis force plate array used to measure the ground reaction forces during the running motion of an ant

A terrestrial insect can perform agile running maneuvers. However, the balance of ground reaction forces (GRFs) between each leg in an insect have remained poorly characterized. In this report, we present a micro force plate array for the simultaneous measurement of the anterior and vertical components of GRFs of multiple legs during the running motion of an ant. The proposed force plate, which consists of a 2000 µm × 980 µm × 20 µm plate base as the contact surface of an ant's leg, and the supported beams with piezoresistors on the sidewall and surface are sufficiently compact to be adjacently arrayed along the anterior direction. Eight plates arrayed in parallel were fabricated on the same silicon-on-insulator substrate to narrow the gap between each plate to 20 µm. We compartmented the plate surface into 32 blocks and evaluated the sensitivities to two-axis forces in each block so that the exerted forces could be detected wherever a leg came into contact. The force resolutions in both directions were under 1 µN within ±20 µN. Using the fabricated force plate array, we achieved a simultaneous measurement of the GRFs of three legs on one side while an ant was running.

A Retrospective Study of the Yo-Yo IE2 Test: Can It be Used to Differentiate Between Different Levels of Futsal Referees?

Recently FIFA have called on referees to be fitter and to look like athletes therefore the aim of this research was to retrospectively examine the results from the fitness test results undertaken by Futsal referees operating in and below the National Futsal League. Futsal is the FIFA sanctioned form of 5 a side football and is controlled by two referees who operate up and down the touchlines either side of the pitch. Research has shown that the referees operating at an average intensity of 76% heart rate maximum (HRmax)HRMAX and spent more time sprinting and working at high intensity compared to referees in the 11 a side game. Currently FIFA recommend a. and as such the current 1000 m run, but this is not thought to match the actual movements or intensity of futsal referees or matches. As such the Yo-Yo IE2 test was introduced this season as it has been found to correlate highly with high intensity running (r=0.75; p<0.05). Twenty-two National group and 36 Non-national group futsal referees underwent pre-season testing which in-cooperating the Yo-Yo Intermittent Endurance Level 2 Fitness Test, a sprint test and a 70 m agility run test. The result showed a trivial effect size difference for Yo-Yo IE2 test distance (0.21), a small effect size difference for 40 m speed test and a extremely large effect size difference for agility run. A moderate to large correlation was found between age and Yo-Yo IE2 distance (r=-0.577) and BMI and Yo-Yo IE2 distance (r=-0.452). Therefore the Yo-Yo IE2 can be used to differentiate between different levels of futsal referees and it may be possible to use the test to identify those referees who show the fitness attributes for further development.

Effect of soccer shoe ball girth differences on fit perception, agility running and running speed perception

Purpose: Soccer shoes influence agility running due to traction properties. Shoe upper fit was identified to effect stability perception of players. However, its influence on agility running performance is unclear. This study examined whether soccer shoe ball girth dimension affects fit perception, agility running, and running speed perception. It was hypothesised that a narrower shoe ball girth would improve running performance.Methods: Thirty male soccer players performed agility runs in three experimental shoe conditions, featuring the same length but different ball girth (narrow, medium, wide). Fit perception, running time, and running speed perception were measured by a timing gate and perception protocols. One-way repeated measures analysis of variance (ANOVA) and Friedman tests were used to identify differences among shoe conditions, complemented by least significant difference (LSD) post-hoc and Wilcoxon signed rank tests.Results: Fit perception scores revealed that the medium and the wide shoe condition were perceived to have wider ball girth compared to the narrow condition (p < 0.05). No agility running performance and running speed perception differences were detected among shoe conditions. Anatomical foot measures were only weakly, or not correlated to fit perception at corresponding shoe locations.Conclusion: Fit differences of soccer shoes, only regarding their ball girth, did not influence agility running performance. This indicates a lesser importance of fit properties for achieving best running performance compared to traction properties, when ball girth is varied in shoes featuring a given shoe length. Individual lacing procedures were used in this study and may have compensated for the fit differences of the experimental shoes of this research.

Growth Hormone and Muscle Strength in Children

When I was asked to write an editorial to comment on the article by Simon et al (1) in this issue of the Journal, I felt it would be a real challenge. The use of GH therapy in children has provoked more discussion in the last few years from a legal, journalistic, economical, and even political point of view than from medical and scientific perspectives. I decided to take the challenge and to comment on the facts as I perceive them. An impact of recombinant human GH (rhGH) on muscle strength is controversial. As physicians, we are essentially warned about rhGH doping in professional and Olympic athletics, with the presumption that it has a beneficial effect on muscle strength. This is despite the fact that there appears to be no evidence that rhGH enhances muscle strength, power, or aerobic capacity in trained adult athletes. However, rhGH does increase modestly anaerobic exercise capacity when administered alone and to a greater extent when combined with testosterone (2). Thus, despite the abuse of rhGH by athletes, there is little support of performance benefit except for an effect on anaerobic exercise capacity (2). In GH-deficient patients, replacement of rhGH improves aerobic exercise capacity, although it remains to be elucidated whether this is due to the direct effect on muscle function or on other factors influencing cardiovascular function, well-being, and motivation. Long-term rhGH replacement in excess of 12 months seems to be required for improved muscle strength to take place in GH-deficient adult subjects (2). It has been reported that 10 years of rhGH replacement therapy in GH-deficient adults increased muscle strength during the first half of the study and then protected partly against the normal decline withage inmusclestrength,resulting inapproximatelynormalized muscle strength after 10 years (3). Even fewerdataareavailable inchildren,with theexception of data gathered from children affected with Prader-Willi syndrome(PWS),araregenetic formofobesitywithhypothalamic involvement that leads to GH deficiency. One group assessed the impact of rhGH therapy begun early in life on the natural history of PWS and compared height, body composition, and strength in similar-age children with PWS naive to rhGH with those treated with hGH for 6 years (4). Motor strength testing included broad jump, agility run, sit-ups, and upper arm strength assessments. The evaluator of motor strength testing was blinded to the treatment status of each child. PWS children treated with rhGH demonstrated greater motor strength (increased standing broad jump 22.9 2.1 vs 14.6 1.9 inches (P .001) and sit-ups 12.4 0.9 vs 7.1 0.7 repetitions in 30 seconds; P .001). Clear trends were seen in the 2 other areas of the testing, including improved agility run and weight-lift repetitions, although these did not reach statistical significance. Thus, thisnonrandomizedstudysuggestedabeneficialeffecton muscle strength in children affected by PWS. However, these few reports on young active adults, on GH-deficient adults, and on children affected by PWS may not be relevant to the chronically ill and less active children included in the study of Simon et al (1). In this study, the authors evaluated the effects of rhGH on muscle strength in children receiving long-term glucocorticoid therapy. Expected effects of growth hormone on height and body composition were assessed and confirmed, but those will not be commented upon here. This was a pilot study, randomized and controlled, with a delayed-start of rhGH for 12 months. rhGH was started after randomization (month 0) or 6 months later (month 6). A total of 30 children with various diagnoses, on glucocorticoid therapy for a chronic disease, startedat least1year earlierwithheight1SDorat2SDscore (SDS) below and bone age 15 years in boys and 13 years in girls. rhGH was administered at a dose of 0.065 mg/kg/d for 6monthsandtheninthedosagemaintainingserumIGF-1levels

Gender-Specific Influences of Balance, Speed, and Power on Agility Performance

The quick change of direction (i.e., agility) is an important athletic ability in numerous sports. Because of the diverse and therefore hardly predictable manifestations of agility in sports, studies noted that the improvement in speed, power, and balance should result in an improvement of agility. However, there is evident lack of data regarding the influence of potential predictors on different agility manifestations. The aim of this study was to determine the gender-specific influence of speed, power, and balance on different agility tests. A total of 32 college-aged male athletes and 31 college-aged female athletes (age 20.02 ± 1.89 years) participated in this study. The subjects were mostly involved in team sports (soccer, team handball, basketball, and volleyball; 80% of men, and 75% of women), martial arts, gymnastics, and dance. Anthropometric variables consisted of body height, body weight, and the body mass index. Five agility tests were used: a t-test (T-TEST), zig-zag test, 20-yard shuttle test, agility test with a 180-degree turn, and forward-backward running agility test (FWDBWD). Other tests included 1 jumping ability power test (squat jump, SQJ), 2 balance tests to determine the overall stability index and an overall limit of stability score (both measured by Biodex Balance System), and 2 running speed tests using a straight sprint for 10 and 20 m (S10 and S20, respectively). A reliability analysis showed that all the agility tests were reliable. Multiple regression and correlation analysis found speed and power (among women), and balance (among men), as most significant predictors of agility. The highest Pearson's correlation in both genders is found between the results of the FWDBWD and S10M tests (0.77 and 0.81 for men and women, respectively; p < 0.05). Power, measured using the SQJ, is significantly (p < 0.05) related to FWDBWD and T-TEST results but only for women (-0.44; -0.41). The balance measures were significantly related to the agility performance for men but not for women. In addition to demonstrating a known relationship between speed and agility in both genders, and a small but statistically significant relationship between power and agility in women, these results indicate that balance should be considered as a potential predictor of agility in trained adult men.

A Study on Improving Middle-and-Long Distance Running Performance of College Students with Segmented Intensity Indicator Training Method

The track and field teams in colleges and universities are made up of the specially recruited athletes and normally recruited athletes, which are established in order to take part in the matches on and off campus or home and abroad. Extracurricular track and field training is the essential part of the physical education in colleges and universities, indicating the level of physical education on campus. To improve specific endurance, intensity timed running shorter than specific distance is adopted. Super intensity running shorter than specific distance is important in improving middle-distance performance. When using speed agility run, repeated run and regular standard-speed run in exercise, if the specific temporal requirement were not calculated before, it is easy to cause unreasonable physical power distribution. In unplanned run, the speed of each segment can not reach personal specific level. The effect of exercise is bad when your strength is consumed blindly, thus the performance will not improve. Therefore, reasonable time of each segment should be calculated before run and in every exercise, which is important for athletes to create the best performance. The purpose of the study is to explore the use and application of segmented intensity indicator middle and long distance training in colleges. By studying middle and long distance athletes in 6 colleges using segmented intensity indicator training method and comparing the performance before and after the training, the author concludes that this method could effectively improve college middle- and -long distance running performance. On the basis of the training directed by the method of segmented intensity indicator, the extent of the performing improvement before and after the training, and the statistic analysis of this difference of the extent, it is concluded that this study is of great benefit to the training of middle-and-long distance running and achieves good performance.

Anthropometric and Physical Characteristics of Tunisians Young Soccer Players

The aim of this investigation was to provide anthropometric, physical and physiological performance characteristics of Tunisian young soccer players and to examine the relationship between selected parameters according to their playing standard position. One hundred under 13 years old (U-13) male soccer players were tested. They were classified according to their playing standard positions (goalkeeper: GK, defender: DF, midfield: MF, and forward: FW). Testing consisted of anthropometric measurements including weight, height, and body mass index, and performance measures of speed (5, 15, and 20 m), agility run (Agility-15 m and Ball-15 m), vertical jumping, ball shooting, and aerobic capacity (Hoff Dribble Test and Yo-Yo intermittent Endurance Run, YYIER). GK were taller and heavier than other players. Significant differences of playing positions for the majority of the physical tests include 20 m sprint, Agility-15 m and Ball-15 m times (all p p p p p p < .01). Multiple regression analyses showed that weight and height were the most significant predictors of 20 m sprint time and the YYIER distance, respectively. In conclusion, performance abilities between positions in young soccer players appear to be different. Anthropometry can discriminate physical capacities and soccer skills providing a scientific rational behind the coaches’ practice of selecting young soccer players.

Reliability, Validity and Minimal Detectable Change of a New Multi-Change of Directionagility Test for Soccer Players

This study examined the test-retest reliability, validity and external responsiveness of a new multi-change of direction agility test (NMAT) designed for soccer players. Forty-four Tunisian soccer players were recruited and were divided into two groups according to their playing levels (International, n = 21 and National, n = 23). Following familiarization, athletes performed squat jump (SJ), countermovement jump (CMJ), running speed test (5 m and 20 m), 15-m agility run (Agility-15 m), 15-m ball dribbling (Ball-15 m), and NMAT and ball dribbling NMAT (Ball-NMAT) in 2 sessions, 48 h apart. The intraclass correlation coef?cient and SEM values were .96 (CI 95%: .94 - .98) and .05 seconds for NMAT and .97 (CI 95%: .94 - .98) and .09 seconds for Ball-NMAT, respectively. The smallest worthwhile changes were greater than their SEM for both NMAT and Ball-NMAT. The MDC95 values were .15 seconds and .25 seconds for NMAT and Ball-NMAT, respectively. Both NMAT and Ball-NMAT were respectively correlated with Agility-15 m (r = .78; p .7 (.85; CI 95%: .71 - .94 and .91; CI 95%: .78 - .97 for NMAT and Ball-NMAT, respectively). These results indicated that NMAT provides excellent absolute and relative reliabilities. The NMAT can distinguish soccer athletes of different competitive levels. Thus, the NMAT may be suitable for field assessment of specific agility of soccer players.

Účinnosť všeobecného a kombinovaného silového tréningu na zmeny rýchlostno-silových schopností mladých hokejistov

Purpose of this study was to compare effects of general strength training with combined maximal strength and plyometrics training. Twelve young ice hockey players were examined and intervened 4-week general strength training (EX1) at first and consequently 4-week, combined training (EX2). Combined training consisted of maximal strength workouts with 2-4 repetitions on 85-95% 1RM and subsequent application of plyometrics workouts with 6-10 repetitions. The training group performed 2 sessions per a week in 3 sets of exercises. The measurements were assessed before, between and after periods and consisted of specific test performed on ice and non-specific tests off ice. The results showed that in EX2 period SJ improved from 33,3 ± 2,89 cm to 34,35 ± 2,80 cm by 1,05 cm (3,2%; p&lt;0,01); CMJ from 36,51 ± 4,39 cm to 37,84 ± 4,36 cm by 1,33 cm (3,6%; p&lt;0,01). Also in EX1 period SJ was changed from 32,48 ± 3,65 cm to 33,3 ± 2,89 cm (p&lt;0,05). Anaerobic alacticpower (AAV) changed significantly in EX1 period from 42,09 ± 4,48 W.kg-1 to 42,72 ± 4,61 W.kg-1 (p&lt;0,01) afterwards in EX2 period to 43,78 ± 4,44 W.kg-1 (p&lt;0,01). In jumping performances we measured in both periods significant improvements; standing long jump (SZM) in EX1 period from 246,25 ± 11,07 cm to 249,17 ± 10,32 cm (p&lt;0,01) then in the end of EX2 period 253,58 ± 9,83 cm (p&lt;0,01). Standing triple jump (3SK), agility run (10x5) and all specific test on ice were significant changes recorded only in EX2 period. 3SK from 722,42 ± 29,58 cm to 727,50 ± 30,64 cm; 10x5m from 17,00 ± 0,57 s to16,90 ± 0,57 s (p&lt;0,01); on ice speed tests (1x36m) from 4,95 ± 0,10 s to 4,88 ± 0,09 s by 1,4% (p&lt;0,01); (6x9m) from 13,73 ± 0,48 s to 13,63 ± 0,51 s by 0,8% (p&lt;0,05); in speed endurance ice hockey skating test (Okr) form 14,79 ± 0,18 s to 14,67 ± 0,20 s o 0,8% (p&lt;0,05). Skills ice hockey test parameters (Sla) did not changed significantly in EX1 neither in EX2 period. It could be concluded that both periods had effect on motor performance enhancement, but EX2 training period was more sufficient for improvement in speed-strength abilities especially in specific condition on ice.

Ankle Stabilizers Affect Agility but Not Vertical Jump or Dynamic Balance Performance

Ankle stabilizers can reduce ankle sprain incidence and severity by limiting range of motion. Still whether using them affects performance remains unclear. The authors compared effects of 3 ankle stabilizers, tape, lace-up (Swede-O Ankle Lok), and semirigid (Air-Cast Air-Stirrup) braces, and a nonsupport control on vertical jump (Sargent Jump Test), agility (Right-Boomerang Run test), and dynamic balance (Modified Bass Test) in 10 volunteers (4 males, 6 females; 25.6 ± 2.8 years, 167.8 ± 13.7 cm, 61.4 ± 10.7 kg) using repeated-measures ANOVAs. Participants had similar vertical jump (P = .27; control = 41.40 ± 11.89 cm, tape = 37.90 ± 7.92 cm, Swede-O = 41.40 ± 11.89 cm, Air-Cast = 39.29 ± 10.85 cm) and dynamic balance (P = .08; control = 92.50 ± 2.46, tape = 91.55 ± 3.53, Swede-O = 97.00 ± 5.32, Air-Cast = 89.40 ± 6.08) but differing agility scores (P = .03; control = 13.55 ± 1.35 seconds, tape = 14.03 ± 1.5 seconds, Swede-O = 14.10 ± 1.36 seconds, Air-Cast = 14.14 ± 1.41 seconds). Post hoc tests revealed a significant difference (P = .03) between control and Air-Cast but not between Swede-O (P = .06) or tape (P = .07). Effect size (d) analyses indicated that compared with control, all stabilizers trended to increase agility run times (tape, d = 0.33; Swede-O, d = 0.40; Air-Cast, d = 0.43). Since participants primarily required sagittal plane motion when jumping vertically and had relatively slow directional changes in the dynamic balance test, wearing ankle stabilizers did not hamper jump or balance. However, ankle stabilizers hindered participants' ability to perform quick directional changes required in the agility test, with the most rigid stabilizer (Air-Cast) affecting agility the most. Clinicians should be aware that ankle stabilizers may affect some performance measures (agility) but not others (jumping, balance) and continue examinations in larger cohorts. Therapeutic, Level II.

Rugby Union Contact Skills Alter Evasive Agility Performance during Attacking Ball Carries

Rugby union is a collision sport where evasive agility running patterns and the tackle contest determine the effectiveness of attacking ball carries. This study used three-dimensional kinematic analysis to examine the running technique of eight highly trained rugby union players during three rugby based reactive (in response to a defender positioned at the side-step) agility conditions (non-contact, contact and fend). The fend condition involved pushing a defender away with the upper body during the side-step and both fend and contact conditions required impact with an additional defender at the straighten-step, simulating a rugby tackle. Results demonstrated that a reduction in the relative height of the centre of mass relative to standing height (%CM) occurred at the straighten-step during the contact condition (47.2 ±1.9 %CM) compared to the non-contact condition (49.1 ±1.8 %CM, p &lt;.001). The fend condition was then shown to increase %CM at the straighten-step (48.4 ±2.7 %CM) when compared to the contact condition (47.2 ±1.9 %CM, p = .017). However this difference was not observed at tackle impact during the straighten-step, with similar %CM values for fend (45.1 ±3.4 %CM) and contact conditions (44.6 ±2.6 %CM, p = .205). Further analysis showed that the number of steps displayed between the side-step and straighten-step ( transition phase) altered the %CM, with one step during the transition phase increasing %CM (49.3 ±1.5 %CM) compared to two transition phase steps (46.9 ±1.6 %CM, p &lt; .001) and no transition phase steps (46.5 ±1.6 %CM, p &lt; .001). The changes to running technique during agility conditions involving tackle situations highlight the need for running programs in rugby union to meet the specific requirements of match-play activities.

Fitness Determinants of Repeated-Sprint Ability in Highly Trained Youth Football Players

Variations in rates of growth and development in young football players can influence relationships among various fitness qualities. To investigate the relationships between repeated-sprint ability and other fundamental fitness qualities of acceleration, agility, explosive leg power, and aerobic conditioning through the age groups of U11 to U18 in highly trained junior football players. Male players (n = 119) across the age groups completed a fitness assessment battery over two testing sessions. The first session consisted of countermovement jumps without and with arm swing, 15-m sprint run, 15-m agility run, and the 20-m Shuttle Run (U11 to U15) or the Yo-Yo Intermittent Recovery Test, Level 1 (U16 to U18). The players were tested for repeated-sprint ability in the second testing session using a protocol of 6 × 30-m sprints on 30 s with an active recovery. The correlations of repeated-sprint ability with the assorted fitness tests varied considerably between the age groups, especially for agility (r = .02 to .92) and explosive leg power (r = .04 to .84). Correlations of repeated sprint ability with acceleration (r = .48 to .93) and aerobic conditioning (r = .28 to .68) were less variable with age. Repeated-sprint ability associates differently with other fundamental fitness tests throughout the teenage years in highly trained football players, although stabilization of these relationships occurs by the age of 18 y. Coaches in junior football should prescribe physical training accounting for variations in short-term disruptions or impairment of physical performance during this developmental period.

Effect Of Oral Contraceptive Cycle Phases On Physical Fitness Components in Nonprofessional Athletic Females

PURPOSE: The purpose of this study was to examine whether physical fitness components (flexibility, handgrip, agility, cardiovascular endurance and body composition) are affected by hormonal fluctuation within a monophasic oral contraceptive (OC) cycle. METHODS: Twenty eumenorrheic nonprofessional athletic females (Mean ± SD; age: 25.7±5.7 yr, body mass: 56 ±6.65 kg, height: 1.60±4.6 m, BMI: 22.4±2.8 kg/m2) using pill (at least from 18 months before entering in the present study) were tested at two different times of a single OC cycle, during High Hormone Phase (HHP: days 19-21) and Low Hormone Phase (LHP: days 4-6). Handgrip was measured three times by dynamometer and the best performance was recorded for statistical analysis. The percentage of total body fat was measured by taking the girth measurements at abdomen, right thigh and right forearm with a measuring tape. Agility, flexibility and cardiovascular endurance were measured by Illinois agility run test, sit and reach test and multistage fitness test, respectively. RESULTS: There was a significant difference between phases for VO2max which at LHP (27.9±2.9 mls/kg/mi (was 2.2% higher than HHP 27.3±2.9 mls/kg/mi) (P<0.05). Body mass was significantly1.9) %) higher at HHP compared to LHP (P<0.05). Body composition was affected significantly by OC cycle. Body fat percentage and lean body fat was significantly higher at HHP than LHP by 0.8% and 1.1%, respectively (P<0.05). But there was no difference in other physical fitness components. CONCLUSIONS: It is concluded that nonprofessional athletic females may experience significantly variation in VO2max, body mass and body composition throughout an OC cycle that could be detrimental to performance.

Effects of growth hormone on muscle strength, tone and mobility of children with Prader-Willi syndrome.

Objective Prader-Willi Syndrome (PWS) is a genetic syndrome presenting with severe hypotonia and decreased agility. Growth Hormone (GH), which is often used in these patients to treat short stature and obesity, seems improve hypotonia, physical strength, activity, and locomotor developmental ability. The aim of this study was to find the effects of growth hormone on agility and strength of these patients. Material & Methods In a prospective randomized controlled clinical trial in an out-patient pediatric endocrine clinic in Tehran, 21 PWS children (12 boys and 9 girls, 4 to 9 years old) were divided into either GH-treated or control groups and followed for two years. Agility run, sit ups, weight lifting, and inspiratory and expiratory strength were considered as the main outcome measures. Results All the outcome measures of the GH treated group showed a significant improvement compared to the control group. Conclusion GH causes a significant improvement in agility and strength of PWS children. Key words: Preder-willi syndrome; PWS; growth hormone;agility; strength

Effect of Warm-Ups Involving Static or Dynamic Stretching on Agility, Sprinting, and Jumping Performance in Trained Individuals

The objective of the present study was to investigate the effects of static and dynamic stretching alone and in combination on subsequent agility, sprinting, and jump performance. Eight different stretching protocols: (a) static stretch (SS) to point of discomfort (POD); (b) SS less than POD (SS<POD); (c) dynamic stretching (DS); (d) SS POD combined with DS (SS POD + DS); (v) SS<POD combined with DS (SS<POD + DS); (vi) DS combined with SS POD (DS + SS POD); (vii) DS combined with SS<POD (DS + SS<POD); and (viii) a control warm-up condition without stretching were implemented with a prior aerobic warm-up and followed by dynamic activities. Dependent variables included a 30-m sprint, agility run, and jump tests. The control condition (4.2 +/- 0.15 seconds) showed significant differences (p = 0.05) for faster times than the DS + SS<POD (4.28s +/- 0.17) condition in the 30-m (1.9%) sprint. There were no other significant differences. The lack of stretch-induced impairments may be attributed to the trained state of the participants or the amount of time used after stretching before the performance. Participants were either professional or national level elite athletes who trained 6-8 times a week with each session lasting approximately 90 minutes. Based on these findings and the literature, trained individuals who wish to implement static stretching should include an adequate warm-up and dynamic sport-specific activities with at least 5 or more minutes of recovery before their sport activity.