Plyometric training has always been a topic of interest in terms of sport perfor-mance enhancement and development. The most relevant and up-to-date data has been reviewed to try to answer the question “what kind of plyometric training to use” to improve ones’ performance. The present study demonstrates the use of re-active strength index (RSI) and force-velocity profiling. In the text there is also a presentations of common jumping tests that help practitioners to establish a profile of an athlete. Main findings of this study are: general strength should be developed alongside reactive strength qualities, plyometric training optimized and guided by RSI is highly effective in improving reactive strength ability, demands of a sport determine the manner in which plyometric exercises should be performed, RSI can be used as a representation of neuromuscular fatigue, force-velocity (F-v) approach may help improve the training practice for performance in explosive push-off ac-tions like jumping, through a more efficient monitoring and understanding of the individual determinants of athletic performance, showing the sensitivity of the F-v profile to specific training programs can result in either maximal force or velocity capabilities improvements (determination of F-v imbalances or FVimb) – which is termed “optimized training” and it has been found that an optimized and individu-alized training program specifically addressing the FVimb is more efficient for im-proving jumping performance than traditional resistance training.

Aim The aim of the study was to identify the difference between unilateral and bilateral training and their effect on female handball players sprint acceleration and change of direction (COD) ability. The research question was “What differences are there between the effect of combined training performed unilaterally and training performed bilaterally on female handball players’ sprint acceleration ability and COD ability?” Method 60 female (age: 20 ± 5yr) handball players participated in the study, 30 in each group. A loss of 30 subjects occurred, leaving total of 30 subjects finished the study, 15 in each group. The subjects performed two tests before initiating a combined training protocol, inducing strength and plyometric exercises. The first test consisted of a 10-meter straight sprint that was also divided into a 5-meter split, which measured their sprint acceleration by using Ivar Run System. The second test was a modified version of Spasic’s (2015) handball specific COD assessor. After the baseline-test, the subjects participated in a six-week long training protocol, one plyometric workout a week and one strength workout a week. Once the six weeks were completed, the same tests were performed. The data was recorded in Microsoft Excel (2016, Seattle, USA) and analyzed in IBM SPSS (2013, version 22.0, New York, USA).  Results Statistically, unilateral training has proven to be a more effective training method to improve the first 5-meters (p=0,013) of the 10-meter sprint acceleration test and not the other areas. Whilst bilateral training has proven to be more effective training method to improve the total time of the 10-meter sprint acceleration test (p=0,035). Both groups have statistically shown no significant difference in the COD-ability test. Conclusion Crucial standardization errors were made during this study, which in turn could have impaired the results greatly. A cautious approach to a solid conclusion should be considered, due to the standardization errors and the fact, that the subjects were not used to a training protocol being systematically structured. More research with a similar perspective has to be brought about, focusing on the long-term effect and maybe even on elite players. / Syfte och frågeställningar Studiens syfte var att ta reda på om unilateralt baserat träning eller om bilateralt baserat träning var effektivast för att förbättra sprint acceleration och riktningsförändringsförmåga (COD). Frågeställningen lyder; Skiljer sig effekten av kombinerat träning som utförs unilateralt från bilateralt på kvinnliga handbollsspelare som tävlar på amatörnivå. Metod 60 kvinnliga handbollsspelare (age: 20 ± 5yr) deltog i studien. Totalt genomförde 30 stycken deltagare hela studien, 15 per grupp, vilket innebär ett bortfall på 30 stycken. Innan träningsperioden började fick deltagarna genomföra två förtester. Första testet var ett 10-meters sprint accelerationstest, som hade splittider på 5-meter, andra testet var en modifierad Spasics (2015), som är ett riktningsförändringsförmågatest. De testades tider mättes med IVAR Run system. Efter testerna, genomförde deltagarna ett sex-veckors långt träningsprogram, varje vecka genomfördes ett styrkepass och ett plyometriskt träningpass. Eftertester genomfördes efter träningsperioden, resultatet från testerna antecknades i Microsoft Excell (2016, Seattle, USA) och analyserades i IBM SPSS (2013, version 22.0, New York, USA). Resultat Resultatet visar att unilateral träning är en mer effektive träningsmetod för att förbättra de första 5-meterna (p=0,013) i 10-meter sprint accelerationstestet, men inte i de andra delarna. Däremot visar det sig att bilateral träning har en statistiskskillnad (p=0,035) på hela 10-meters sprint accelerationstestet, men inte de första eller sista 5-meterna var för sig. Både grupperna visade ingen statistiskskillnad i riktningsförändringstestet. Slutsats Standardiseringsmisstag gjordes under studiens gång, som kan ha haft direkt påverkan på resultatet. Innan en slutsatsen dras, bör man ta hänsyn till misstagen som begåtts ur ett standardiseringsperspektiv och att deltagarna var ej vana att genomföra ett träningsprogram som var systematiskt strukturerat. Mer forskning inom samma område, utifrån samma perspektiv behövs göras, särskilt långsiktiga studier och kanske även på elitspelare.

Thesis (MSportwet)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The purpose of this study was to investigate the influence of a six-week plyometric training programme on the explosive power, speed and agility as well as certain physiological characteristics and the physical fitness of rugby players. Thirty subjects, that include the first and second rugby teams of the Paul Roos Gymnasium participated in the study. After a thorough evaluation of their medical history, their health status was confirmed as being “apparently healthy” and fit for participation in the project. The subjects were divided into two groups. The experimental group followed a specially designed plyometric training programme in addition to their conventional rugby training, while the control group persisted with the conventional rugby training for the season. Body fat percentage was measured and specific girth measurements were taken to assess physiological changes. Cardiovascular fitness was evaluated by means of the threeminute step test and muscle endurance by means of the push-up and sit-up tests in order to assess the physical fitness of the subjects. The explosive power, speed and agility of the subjects were assessed by means of the agility test [T-drill], ten-meter speed test, Sargent vertical jump test, depth jump test, standing triple jump and the medicine ball chest pass. All measurements and tests were taken before and after the six-week intervention programme of plyometric training. With regards to physiological changes the results showed that the plyometric training programme had a positive effect on the experimental group. The body fat percentage of the experimental group showed a significant decrease and the circumference of their thighs, calves, arms and waist increased. Their chest circumferences did, however, not increase, which might be due to the fact that the plyometric exercises were more specifically aimed at the lower body muscle groups. The results pertaining to physical fitness were mixed. There was a significant improvement (p<0,01) in the cardiovascular fitness of the experimental group while that of the control group stayed relatively constant (p=1,0). With regards to muscle endurance, the control group fared significantly better in the push-up test than the experimental group, while the experimental group fared significantly better in the sit-up test than the control group. The six-week plyometric intervention programme had a statistically significant effect on the performance of the experimental group as compared to the control group, when biomotor skills were assessed. It was concluded that the addition of the specific plyometric exercises to a conventional rugby-training programme would improve the speed, explosive power and agility of rugby players significantly. Beneficial anthropometric changes as well as improved cardiovascular fitness would be additional benefits of a plyometric training programme. The findings of this research suggest that the value of plyometric exercises to motor skills, specific physiological characteristics and physical fitness should not be underestimated and that the trainers and coaches should be informed in this regard. To establish the positive effects of plyometrics as a functional cross training regime for rugby players, more comprehensive research is, however, recommended. / AFRIKAANSE OPSOMMING: Die doel van die navorsing was om die effek van ‘n ses-weeklange pliometriese oefenprogram op die eksplosiewe krag, spoed, ratsheid asook sekere fisiologiese karaktereienskappe en die fisieke fiksheid van rugbyspelers te ondersoek. Dertig spelers, wat lede van die eerste en tweede rugbyspan van Paul Roos Gimnasium hoërskool ingesluit het, het aan die studie deelgeneem. Na deeglike evaluering van hulle mediese geskiedenis, is hulle gesondheidsvlakke goedgekeur vir deelname in die studie. Die spelers is in twee groepe verdeel. Die eksperimentele groep het ‘n spesiale pliometriese oefenprogram gevolg, saam met die konvensionele rugby-oefensessies. Die kontrole groep het slegs aan die konvensionele rugby-oefensessies vir die seisoen deelgeneem. Persentasie liggaamsvet en spesifieke omtrekmates is genoteer om die fisiologiese veranderinge te evalueer. Kardiovaskulêre fiksheid is deur middel van ‘n drie-minute opstaptoets geëvalueer en spieruithouvermoë deur middel van opstoot-en opsittoetse om sodoende die speler se fisieke fiksheid te evalueer. Die ratsheid, spoed en eksplosiewe krag van die spelers is deur die ratsheidstoets (T-drill), tien-meter spoedtoets, Sargent vertikale sprongtoets, diepte sprongtoets, staande driesprong en die medisynebal-gooitoets bepaal. Al die bogenoemde toetse en assessering is voor en na die ses-weke intervensie program van pliometriese oefening gedoen. Met betrekking tot die fisiologiese veranderinge, dui die resultate aan dat die pliometriese oefenprogram ‘n positiewe effek op die eksperimentele groep gehad het. Die eksperimentele groep se persentasie liggaamsvet het beduidend verlaag en daar was ‘n neiging tot toename in omtrekmates van die bobeen, kuite, arms en middel. Die borsomtrekmate het egter nie vergroot nie, en kan toegeskryf word aan die feit dat die pliometriese oefenprogram op die ontwikkeling van die spiere in die onderlyf gefokus het. Die resultate ten opsigte van die fisieke fiksheid was eenders vir die twee groepe. Daar was ‘n neiging tot verbetering in die kardiovaskulêre fiksheid van die eksperimentele groep, terwyl die kontrole groep konstant gebly het. Met betrekking tot spieruithouvermoë het die kontrole groep in die opstoottoets verbeter in vergelyking met die eksperimentele groep. Die eksperimentele groep het egter weer verbeter (p<0,01) in die opsittoets, terwyl die kontrole groep konstant (p=1,0) gebly het. Die eksperimentele groep het statisties betekenisvol in die biomotoriese vaardigheidtoetse verbeter na die ses-weeklange pliometriese oefenprogram. Die kontrole groep het geen verbetering getoon nie. Die gevolgtrekking is dat ‘n kombinasie van ‘n pliometriese oefenprogram en konvensionele rugby-oefening kan lei tot die verbetering van spoed, eksplosiewe krag en ratsheid van spelers. Positiewe antropometriese veranderinge sal addisionele voordele van die pliometriese oefenprogram wees. Die bevinding van die navorsing is dat die waarde van pliometriese oefening vir biomotoriese vaardighede, spesifieke fisiologiese eienskappe en fisieke fiksheid nie onderskat moet word nie en dat afrigters in hierdie opsig ingelig word. Om die positiewe effek van pliometrie as ‘n funksionele alternatiewe oefenmetode vir rugbyspelers te bewys, word meer intense navorsing oor die effek van die spesifieke oefenmetode aanbeveel.

Background: Football (Soccer) is arguably the most popular sport in the international sporting arena. A survey conducted by FIFA (Fédération International de Football Association) (FCPA, 2000) indicated that there are 240 million people who regularly play soccer around the world. Internationally, there are 300 000 clubs with approximately 1.5 million teams. In South Africa, there were 1.8 million registered soccer players in 2002/2003 (Alegi, 2004). Although youth players are predominantly amateurs and have no financial value for their clubs or schools, their continued health and safety are still of vital importance. There are some clubs which contract development players at 19 years of age in preparation for playing in their senior sides and these young players should be well looked after, to ensure a long career playing soccer. Being able to predict injuries and prevent them would be of great value to the soccer playing community. Aims: The main aim of this research was to create a statistical predictive equation combining biomechanics, balance and proprioception, plyometric strength ratios of ND/Bil (Non dominant leg plyometrics/ Bilateral plyometrics), D/Bil (Dominant leg plyometrics/ Bilateral plyometrics) and ND+D/Bil (Non dominant leg + dominant leg plyometrics/ Bilateral plyometrics) and previous injuries to determine a youth soccer player's risk of the occurrence of lower extremity injuries. In the process of reaching this aim it was necessary to record an epidemiological profile of youth soccer injuries over a two season period. It was also necessary to record a physical profile of, and draw comparisons between, school and club youth soccer players. Following the creation of the prediction model a preventative training programme was created for youth soccer players, addressing physical shortcomings identified with the model. Design: A prospective cohort study Subjects: Schoolboy players from two schools in the North West Province, as well as club players from three age groups were used for this study. Players from the U/16 and U/18 teams in the two schools were tested prior to the 2007 season. Players from the U/17, U/18 and U/19 club development teams were tested prior to the 2008 season. The combined total number of players in the teams amounted to 110 players. Method: The test battery consisted of a biomechanical evaluation, proprioceptive and plyometric testing and an injury history questionnaire. The Biomechanical evaluation was done according to the protocol compiled by Hattingh (2003). This evaluation was divided into five regions with a dysfunction score being given for each region. A single limb stance test was used to test proprioception. A Sergeant jump test was utilised using the wall mark method to test plyometric jumping height. A previous injury questionnaire was also completed on all players prior to testing. Test subjects from the schools were tested with the test battery prior to commencement of the 2007 season. The testing on the club teams was undertaken prior to the 2008 season. Injuries were recorded on the prescribed injury recording form by qualified Physiotherapists at weekly sports injury clinics at each of the involved schools and clubs. The coaching staff monitored exposure to training activities and match play on the prescribed recording forms. These training and match exposure hours were used, along with the recorded injuries for creating an epidemiological profile. Injuries were expressed as the amount of injuries per 1000 play hours. Logistical regression was done by using the test battery variables as independent variables and the variable injured/not injured as dependent variable (Statsoft, 2003). This analysis created prediction functions, determining which variables predict group membership of injured and non injured players. Results: There were 110 youth players involved in the research study from seven teams and four different age groups. There were two groups of U/16 players, an U/17 group, three U/18 groups and an U/19 group. The players were involved in a total of 7974 hours of exposure to training and match play during the seasons they were monitored. The average age of the players was 16.6 years. The majority of players were right limb dominant (83.6%) and 65.7% of players failed a single limb stance test. The mean jump height for both legs combined was 33.77cm, with mean heights of 22.60cm for dominant leg jump and 22.66cm for the non dominant leg. In the biomechanical evaluation of the lower leg and foot area, the average youth player presented with adaptation of toes, normal or flat medial foot arches, a normal or pronated rear foot in standing and lying and a normal or hypomobile mid-foot joint. Between 42.7% and 51.8% of players also presenting with decreased Achilles tendon suppleness and callusing of the transverse foot arch. The youth profile for the knee area indicated that the players presented with excessive tightness of the quadriceps muscles, normal patella tilt and squint, normal knee height, a normal Q-angle, a normal VMO: VL ratio and no previous injuries. This profile indicated very little dysfunction amongst youth players for the knee area. For the hip area, the youth profile was described as follows: There was shortening of hip external rotators, decreased Gluteal muscles length, normal hip internal rotation and no previous history of injury. Between 38.2% and 62.7% of players also exhibit shortened muscle length of the adductor and Iliopsoas muscles and decreased length of the ITB (Iliotibial Band). In the Lumbo-pelvic area there was an excessive anterior tilt of the pelvis with normal lumbar extension, side flexion, rotation and lumbar saggital view without presence of scoliosis. Between 58.18% and 65.45% of players presented with an abnormal coronal view and decreased lumbar flexion. Between 41.81% and 44.54% of players also presented with leg length, ASIS, PSIS, Cleft, Rami and sacral rhythm asymmetry. The similarity of the results for these tests in all players contributed to a new variable called 'SIJ dysfunction'. This was compiled from the average of the scores for Leg length, ASIS, PSIS, Cleft, Rami and Sacral rhythm, which was also considered for inclusion in the prediction model. The neurodynamic results of youth players indicated that approximately between 44.54% and 50.91% of players presented with decreased Straight leg raise and prone knee bend tests. The total combined dysfunction scores for the left and right sides were 17.091 and 17.909 respectively, indicating that there were higher levels of dysfunction on the right side than the left. This increased unilateral dysfunction could probably be attributed to limb dominance and increased use of the one leg for kicking and passing during the game. In the epidemiological study on youth players, there were a total of 49 training injuries and 52 match injuries. The total injury rate for youth players was 12.27 injuries/1000 hours, with a total match injury rate of 37.12 injuries/1000 match hours. The combined training injury rate was 7.17 injuries/1000 training hours. 87.13% of injuries were of the lower limb area and the individual areas with the highest percentage of injuries were the Ankle (25.74%), Knee (19.80%), Thigh (15.84%) and Lower leg (14.85%).The totals for youth players indicated that sprains (30.69% of total), strains (27.72% of total) and contusions (27.72% of total) were the most common causative mechanism of injuries. The severity of injuries show 'zero day' (no time off play) injuries to be the most common type (35.64%), followed by 'slight' (1 to 3 days off play) (33.66%) and 'minor' (4 to 7 days off play) (14.85%). School players had higher injury rates than club players but the severity of injuries to club players was higher, with longer absences from play. Non-contact injuries accounted for 52.47% of the total with 46.53% being contact injuries. School players had lower levels of non-contact injuries than club players, which correlated well with lower dysfunction scores recorded for school players during the biomechanical evaluations. This demonstrated that there was a definite relationship between levels of biomechanical dysfunction and the percentage of non-contact injuries in youth players, which formed the premise of the creation of a prediction model for non-contact youth soccer injuries. The next step in the creation of a prediction model was to identify the variables that discriminated maximally between injured and non-injured players. This was done using stepwise logistic regression analysis. After the analysis, ten variables with the largest odds ratios were selected for inclusion in the prediction model to predict non-contact injuries in youth soccer players. The prediction model created from the stepwise analysis presented as follows: P (injury)= exp(-8.2483 -1.2993a + 1.8418b + 0.2485c + 4.2850d + 1.3845e + 1.3004f-1.1566g + 1.8273h-0.9460i-0.5193j) l + exp(-8.2483-1.2993a + 1.8418b+ 0.2485c + 4.2850d + 1.3845e + 1.3004f-1.1566g + 1.8273h-0.94601-0.5193J) a = Toe dysfunction b = Previous ankle injury c = Ankle dysfunction d = SIJ dysfunction e = Lumbar Extension f = Straight Leg Raise g = Psoas length h = Patella squint i = Gluteal muscle length j = Lumbar dysfunction P = probability of non contact injury exp(x) = e x , with e the constant 2.7183 In the ankle area, the toe positional test, previous ankle injury history and combined ankle dysfunction score were included in the prediction model. In the knee area, the patella squint test was included in the model. In the hip area, the Psoas component of the Thomas test was included, along with the Gluteal muscle length test. In the Lumbo-pelvic area, the SIJ dysfunction (average of Leg length, ASIS, PSIS, Rami, Cleft and Sacral rhythm tests), lumbar extension test and lumbar dysfunction scores were included in the prediction model. In the neurodynamic area, the Straight leg raise test was included in the prediction model. The prediction model therefore contained tests from all five the bio mechanical areas of the body. Overall, this model correctly predicted 86.91% of players as either injured or not-injured. The I value (effect size index for improvement over chance) of the prediction model (1=0.67), along with the sensitivity (65.52%), specificity (94.87%), overall correct percentage of prediction (86.91%) and Hosmer and Lemeshow interferential goodness-to-fit value (X 2(8) = 0.7204), all demonstrated this prediction model to be a valid and accurate prediction tool for non-contact youth soccer injuries A second prediction model, for the prediction of hip and groin injuries amongst youth players, was also created. The prediction model created from the stepwise analysis for groin injuries presents as follows: P (Groin injury)^ exp(-116.2 + 33.5383d + 14.5108k + 4.1972m + 1.9330e + 10.7006f-14.4028n + 48.8751p) l + exp(-116.2 + 33.5383d+14.5108k + 4.1972m + 1.9330e + 10.7006f-14.4028n + 48.8751p) d = SIJ dysfunction k = Previous knee injury m = Previous hip injury e = Lumbar extension f = Straight leg raise n = Limb dominance p = ND/Bil plyometric ratio P = probability of groin injury exp(x) = ex, with e the constant 2.7183 The prediction model for hip and groin injuries included the variables of SIJ dysfunction, previous knee injury, previous hip injury, lumbar extension, straight leg raise, limb dominance and the ratio of non-dominant leg to bilateral legs plyometric height. When all the validifying tests were examined, the I-value (0.64868), sensitivity (66.67%), specificity (98.01%), false negatives (1.98%), false positives (33.33%), Hosmer and Lemeshow goodness-to-fit value (X2(8) = 0.77) and the overall percentage of correct prediction (96.26%) all reflected that this model was an accurate prediction tool for hip and groin injuries amongst youth soccer players. Conclusion: This study showed that it was possible to create a prediction model for non-contact youth soccer injuries based on a pre-season biomechanical, plyometric and proprioceptive evaluation along with a previous injury history questionnaire. This model appears as follows: P (injury)= exp(-8.2483 -1.2993a + 1.8418b + 0.2485c + 4.2850d + 1.3845e + 1.3004f - 1.1566g + 1.8273h - 0.9460i - 0.5193J) l + exp(-8.2483-1.2993a+ 1.8418b + 0.2485c + 4.2850d + 1.3845e + 1.3004f-1.1566g+1.8273h-0.94601-0.5193J) a = Toe dysfunction b=Previous ankle injury c = Ankle dysfunction d= SIJ dysfunction e=Lumbar Extension f = Straight Leg Raise g = Psoas length h = Patella squint i = Gluteal muscle length j = Lumbar dysfunction P = probability of non contact injury exp(x) = ex, with e the constant 2.7183 It was also possible to create a prediction model for non contact hip and groin injuries, which appears as follows: P (Groin injury)= exp(-116.2 + 33.5383d + 14.5108k + 4.1972m + 1.9330e + 10.7006f-14.4028n + 48.8751p) l + exp(-116.2 + 33.5383d + 14.5108k + 4.1972m + 1.9330e + 10.7006f-14.4028n + 48.8751p) d = SIJ dysfunction k = Previous knee injury m = Previous hip injury e = Lumbar extension f = Straight leg raise n = Limb dominance p = ND/Bil plyo metric ratio P = probability of groin injury exp(x) = ex, with e the constant 2.7183 It was also possible to create a prediction model for non contact hip and groin injuries, which appears as follows: P (Groin injury)= exp(-116.2 + 33.5383d + 14.5108k + 4.1972m + 1.9330e + 10.7006f-14.4028n + 48.8751p) l + exp(-116.2 + 33.5383d + 14.5108k + 4.1972m + 1.9330e + 10.7006f-14.4028n + 48.8751p) d = SIJ dysfunction k = Previous knee injury m = Previous hip injury e = Lumbar extension f = Straight leg raise n = Limb dominance p = ND/Bil plyo metric ratio P = probability of groin injury exp(x) = ex, with e the constant 2.7183 Using the hip and groin prediction model, combined with the injury prediction model, injuries in youth soccer players can be predicted. The data for each player should first be substituted into the injury prediction model, to determine the chance of getting injured during the season. The data should then be substituted into the hip and groin injury prediction model, determining the chance of hip and groin injuries during the season. The results from the groin injury prediction model could then be used to exclude groin injuries amongst players. A negative result for the hip and groin injury, which showed a false negative percentage of 1.98%, could be used to determine that an injury that was predicted using the overall injury prediction model, would not be a hip and groin injury. A positive result in the groin injury test could, however, not exclude injuries to other body areas that were predicted by the overall injury prediction model, so the groin injury prediction model could only be used to exclude hip and groin injuries. / Thesis (Ph.D. (Education)--North-West University, Potchefstroom Campus, 2009.

Background: Football (Soccer) is arguably the most popular sport in the international sporting arena. A survey conducted by FIFA (Fédération International de Football Association) (FCPA, 2000) indicated that there are 240 million people who regularly play soccer around the world. Internationally, there are 300 000 clubs with approximately 1.5 million teams. In South Africa, there were 1.8 million registered soccer players in 2002/2003 (Alegi, 2004). Although youth players are predominantly amateurs and have no financial value for their clubs or schools, their continued health and safety are still of vital importance. There are some clubs which contract development players at 19 years of age in preparation for playing in their senior sides and these young players should be well looked after, to ensure a long career playing soccer. Being able to predict injuries and prevent them would be of great value to the soccer playing community. Aims: The main aim of this research was to create a statistical predictive equation combining biomechanics, balance and proprioception, plyometric strength ratios of ND/Bil (Non dominant leg plyometrics/ Bilateral plyometrics), D/Bil (Dominant leg plyometrics/ Bilateral plyometrics) and ND+D/Bil (Non dominant leg + dominant leg plyometrics/ Bilateral plyometrics) and previous injuries to determine a youth soccer player's risk of the occurrence of lower extremity injuries. In the process of reaching this aim it was necessary to record an epidemiological profile of youth soccer injuries over a two season period. It was also necessary to record a physical profile of, and draw comparisons between, school and club youth soccer players. Following the creation of the prediction model a preventative training programme was created for youth soccer players, addressing physical shortcomings identified with the model. Design: A prospective cohort study Subjects: Schoolboy players from two schools in the North West Province, as well as club players from three age groups were used for this study. Players from the U/16 and U/18 teams in the two schools were tested prior to the 2007 season. Players from the U/17, U/18 and U/19 club development teams were tested prior to the 2008 season. The combined total number of players in the teams amounted to 110 players. Method: The test battery consisted of a biomechanical evaluation, proprioceptive and plyometric testing and an injury history questionnaire. The Biomechanical evaluation was done according to the protocol compiled by Hattingh (2003). This evaluation was divided into five regions with a dysfunction score being given for each region. A single limb stance test was used to test proprioception. A Sergeant jump test was utilised using the wall mark method to test plyometric jumping height. A previous injury questionnaire was also completed on all players prior to testing. Test subjects from the schools were tested with the test battery prior to commencement of the 2007 season. The testing on the club teams was undertaken prior to the 2008 season. Injuries were recorded on the prescribed injury recording form by qualified Physiotherapists at weekly sports injury clinics at each of the involved schools and clubs. The coaching staff monitored exposure to training activities and match play on the prescribed recording forms. These training and match exposure hours were used, along with the recorded injuries for creating an epidemiological profile. Injuries were expressed as the amount of injuries per 1000 play hours. Logistical regression was done by using the test battery variables as independent variables and the variable injured/not injured as dependent variable (Statsoft, 2003). This analysis created prediction functions, determining which variables predict group membership of injured and non injured players. Results: There were 110 youth players involved in the research study from seven teams and four different age groups. There were two groups of U/16 players, an U/17 group, three U/18 groups and an U/19 group. The players were involved in a total of 7974 hours of exposure to training and match play during the seasons they were monitored. The average age of the players was 16.6 years. The majority of players were right limb dominant (83.6%) and 65.7% of players failed a single limb stance test. The mean jump height for both legs combined was 33.77cm, with mean heights of 22.60cm for dominant leg jump and 22.66cm for the non dominant leg. In the biomechanical evaluation of the lower leg and foot area, the average youth player presented with adaptation of toes, normal or flat medial foot arches, a normal or pronated rear foot in standing and lying and a normal or hypomobile mid-foot joint. Between 42.7% and 51.8% of players also presenting with decreased Achilles tendon suppleness and callusing of the transverse foot arch. The youth profile for the knee area indicated that the players presented with excessive tightness of the quadriceps muscles, normal patella tilt and squint, normal knee height, a normal Q-angle, a normal VMO: VL ratio and no previous injuries. This profile indicated very little dysfunction amongst youth players for the knee area. For the hip area, the youth profile was described as follows: There was shortening of hip external rotators, decreased Gluteal muscles length, normal hip internal rotation and no previous history of injury. Between 38.2% and 62.7% of players also exhibit shortened muscle length of the adductor and Iliopsoas muscles and decreased length of the ITB (Iliotibial Band). In the Lumbo-pelvic area there was an excessive anterior tilt of the pelvis with normal lumbar extension, side flexion, rotation and lumbar saggital view without presence of scoliosis. Between 58.18% and 65.45% of players presented with an abnormal coronal view and decreased lumbar flexion. Between 41.81% and 44.54% of players also presented with leg length, ASIS, PSIS, Cleft, Rami and sacral rhythm asymmetry. The similarity of the results for these tests in all players contributed to a new variable called 'SIJ dysfunction'. This was compiled from the average of the scores for Leg length, ASIS, PSIS, Cleft, Rami and Sacral rhythm, which was also considered for inclusion in the prediction model. The neurodynamic results of youth players indicated that approximately between 44.54% and 50.91% of players presented with decreased Straight leg raise and prone knee bend tests. The total combined dysfunction scores for the left and right sides were 17.091 and 17.909 respectively, indicating that there were higher levels of dysfunction on the right side than the left. This increased unilateral dysfunction could probably be attributed to limb dominance and increased use of the one leg for kicking and passing during the game. In the epidemiological study on youth players, there were a total of 49 training injuries and 52 match injuries. The total injury rate for youth players was 12.27 injuries/1000 hours, with a total match injury rate of 37.12 injuries/1000 match hours. The combined training injury rate was 7.17 injuries/1000 training hours. 87.13% of injuries were of the lower limb area and the individual areas with the highest percentage of injuries were the Ankle (25.74%), Knee (19.80%), Thigh (15.84%) and Lower leg (14.85%).The totals for youth players indicated that sprains (30.69% of total), strains (27.72% of total) and contusions (27.72% of total) were the most common causative mechanism of injuries. The severity of injuries show 'zero day' (no time off play) injuries to be the most common type (35.64%), followed by 'slight' (1 to 3 days off play) (33.66%) and 'minor' (4 to 7 days off play) (14.85%). School players had higher injury rates than club players but the severity of injuries to club players was higher, with longer absences from play. Non-contact injuries accounted for 52.47% of the total with 46.53% being contact injuries. School players had lower levels of non-contact injuries than club players, which correlated well with lower dysfunction scores recorded for school players during the biomechanical evaluations. This demonstrated that there was a definite relationship between levels of biomechanical dysfunction and the percentage of non-contact injuries in youth players, which formed the premise of the creation of a prediction model for non-contact youth soccer injuries. The next step in the creation of a prediction model was to identify the variables that discriminated maximally between injured and non-injured players. This was done using stepwise logistic regression analysis. After the analysis, ten variables with the largest odds ratios were selected for inclusion in the prediction model to predict non-contact injuries in youth soccer players. The prediction model created from the stepwise analysis presented as follows: P (injury)= exp(-8.2483 -1.2993a + 1.8418b + 0.2485c + 4.2850d + 1.3845e + 1.3004f-1.1566g + 1.8273h-0.9460i-0.5193j) l + exp(-8.2483-1.2993a + 1.8418b+ 0.2485c + 4.2850d + 1.3845e + 1.3004f-1.1566g + 1.8273h-0.94601-0.5193J) a = Toe dysfunction b = Previous ankle injury c = Ankle dysfunction d = SIJ dysfunction e = Lumbar Extension f = Straight Leg Raise g = Psoas length h = Patella squint i = Gluteal muscle length j = Lumbar dysfunction P = probability of non contact injury exp(x) = e x , with e the constant 2.7183 In the ankle area, the toe positional test, previous ankle injury history and combined ankle dysfunction score were included in the prediction model. In the knee area, the patella squint test was included in the model. In the hip area, the Psoas component of the Thomas test was included, along with the Gluteal muscle length test. In the Lumbo-pelvic area, the SIJ dysfunction (average of Leg length, ASIS, PSIS, Rami, Cleft and Sacral rhythm tests), lumbar extension test and lumbar dysfunction scores were included in the prediction model. In the neurodynamic area, the Straight leg raise test was included in the prediction model. The prediction model therefore contained tests from all five the bio mechanical areas of the body. Overall, this model correctly predicted 86.91% of players as either injured or not-injured. The I value (effect size index for improvement over chance) of the prediction model (1=0.67), along with the sensitivity (65.52%), specificity (94.87%), overall correct percentage of prediction (86.91%) and Hosmer and Lemeshow interferential goodness-to-fit value (X 2(8) = 0.7204), all demonstrated this prediction model to be a valid and accurate prediction tool for non-contact youth soccer injuries A second prediction model, for the prediction of hip and groin injuries amongst youth players, was also created. The prediction model created from the stepwise analysis for groin injuries presents as follows: P (Groin injury)^ exp(-116.2 + 33.5383d + 14.5108k + 4.1972m + 1.9330e + 10.7006f-14.4028n + 48.8751p) l + exp(-116.2 + 33.5383d+14.5108k + 4.1972m + 1.9330e + 10.7006f-14.4028n + 48.8751p) d = SIJ dysfunction k = Previous knee injury m = Previous hip injury e = Lumbar extension f = Straight leg raise n = Limb dominance p = ND/Bil plyometric ratio P = probability of groin injury exp(x) = ex, with e the constant 2.7183 The prediction model for hip and groin injuries included the variables of SIJ dysfunction, previous knee injury, previous hip injury, lumbar extension, straight leg raise, limb dominance and the ratio of non-dominant leg to bilateral legs plyometric height. When all the validifying tests were examined, the I-value (0.64868), sensitivity (66.67%), specificity (98.01%), false negatives (1.98%), false positives (33.33%), Hosmer and Lemeshow goodness-to-fit value (X2(8) = 0.77) and the overall percentage of correct prediction (96.26%) all reflected that this model was an accurate prediction tool for hip and groin injuries amongst youth soccer players. Conclusion: This study showed that it was possible to create a prediction model for non-contact youth soccer injuries based on a pre-season biomechanical, plyometric and proprioceptive evaluation along with a previous injury history questionnaire. This model appears as follows: P (injury)= exp(-8.2483 -1.2993a + 1.8418b + 0.2485c + 4.2850d + 1.3845e + 1.3004f - 1.1566g + 1.8273h - 0.9460i - 0.5193J) l + exp(-8.2483-1.2993a+ 1.8418b + 0.2485c + 4.2850d + 1.3845e + 1.3004f-1.1566g+1.8273h-0.94601-0.5193J) a = Toe dysfunction b=Previous ankle injury c = Ankle dysfunction d= SIJ dysfunction e=Lumbar Extension f = Straight Leg Raise g = Psoas length h = Patella squint i = Gluteal muscle length j = Lumbar dysfunction P = probability of non contact injury exp(x) = ex, with e the constant 2.7183 It was also possible to create a prediction model for non contact hip and groin injuries, which appears as follows: P (Groin injury)= exp(-116.2 + 33.5383d + 14.5108k + 4.1972m + 1.9330e + 10.7006f-14.4028n + 48.8751p) l + exp(-116.2 + 33.5383d + 14.5108k + 4.1972m + 1.9330e + 10.7006f-14.4028n + 48.8751p) d = SIJ dysfunction k = Previous knee injury m = Previous hip injury e = Lumbar extension f = Straight leg raise n = Limb dominance p = ND/Bil plyo metric ratio P = probability of groin injury exp(x) = ex, with e the constant 2.7183 It was also possible to create a prediction model for non contact hip and groin injuries, which appears as follows: P (Groin injury)= exp(-116.2 + 33.5383d + 14.5108k + 4.1972m + 1.9330e + 10.7006f-14.4028n + 48.8751p) l + exp(-116.2 + 33.5383d + 14.5108k + 4.1972m + 1.9330e + 10.7006f-14.4028n + 48.8751p) d = SIJ dysfunction k = Previous knee injury m = Previous hip injury e = Lumbar extension f = Straight leg raise n = Limb dominance p = ND/Bil plyo metric ratio P = probability of groin injury exp(x) = ex, with e the constant 2.7183 Using the hip and groin prediction model, combined with the injury prediction model, injuries in youth soccer players can be predicted. The data for each player should first be substituted into the injury prediction model, to determine the chance of getting injured during the season. The data should then be substituted into the hip and groin injury prediction model, determining the chance of hip and groin injuries during the season. The results from the groin injury prediction model could then be used to exclude groin injuries amongst players. A negative result for the hip and groin injury, which showed a false negative percentage of 1.98%, could be used to determine that an injury that was predicted using the overall injury prediction model, would not be a hip and groin injury. A positive result in the groin injury test could, however, not exclude injuries to other body areas that were predicted by the overall injury prediction model, so the groin injury prediction model could only be used to exclude hip and groin injuries. / Thesis (Ph.D. (Education)--North-West University, Potchefstroom Campus, 2009.

Made available in DSpace on 2016-12-08T15:59:05Z (GMT). No. of bitstreams: 1 Resumo Caroline Ruschel.pdf: 185923 bytes, checksum: a474bdb42afcd0223ca7d40071272fd8 (MD5) Previous issue date: 2014-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O princípio do treinamento pliométrico é potencializar a utilização do ciclo de alongamento-encurtamento (CAE). Devido à alta intensidade desse tipo de treinamento e o risco potencial de lesões associado, existe atualmente a proposta de realizá-lo em ambiente aquático, tendo em vista a redução das cargas proporcionada pela ação do empuxo. Entretanto, pouco se sabe sobre as características biomecânicas dos exercícios pliométricos na água, e acredita-se que as condições do meio poderiam dificultar a transição imediata entre a fase excêntrica e a fase concêntrica, pré-requisito fundamental para o funcionamento adequado do CAE. Este estudo teve como objetivo analisar e comparar as características biomecânicas do salto em profundidade (SP) realizado no solo e na água, com imersão ao nível da cintura. Participaram da pesquisa 22 atletas do sexo masculino (19,1±3,7 anos, 73,6,±9,1 kg de massa corporal e 1,83±0,08 m de estatura). Foram analisadas variáveis da componente vertical da força de reação do solo (força máxima e impulso nas subfases excêntrica e concêntrica e força máxima na aterrissagem), cinemáticas (tempo de contato, tempo da subfase excêntrica, tempo da subfase concêntrica, tempo de vôo e deslocamento angular da articulação do joelho) e eletromiográficas (pico de ativação, integral e média da atividade eletromiográfica EMG dos músculos Gastrocnemius Medialis GM, Biceps Femoris BF, e Rectus Femoris RF) durante o SP partindo de 0,4 m. Foram utilizadas duas plataformas de força, um sistema de eletromiografia e um equipamento sincronizador de sinais. A comparação entre os ambientes foi realizada através de testes para amostras dependentes (p<0,05). Conforme esperado, devido à ação de força de empuxo e da resistência, houve aumento significativo na duração de todas as fases do salto (excêntrica, concêntrica e voo), e diminuição da força de reação vertical (excêntrica, concêntrica e de aterrissagem) no ambiente aquático. Não foram encontradas diferenças para o impulso na subfase concêntrica, para os ângulos do joelho no contato após a queda e o voo, e para a flexão máxima e amplitude de movimento durante o contato e a aterrissagem. Em geral, a pré-ativação durante a queda e o voo foi influenciada pelo ambiente, sendo que menores valores foram encontrados para o GM e para o BF na água. A atividade EMG do GM e do RF foi significativamente maior na subfase excêntrica e na aterrissagem no solo, enquanto que na subfase concêntrica, os valores foram maiores na água. A combinação de menores valores de força máxima e impulso, maiores tempo de contato e atividade EMG reduzida durante a subfase excêntrica do SP, pode comprometer o funcionamento adequado do CAE na água. Entretanto, durante a subfase concêntrica, valores de impulso semelhantes entre os ambientes, combinados à maior atividade EMG, evidenciam a sobrecarga oferecida pela resistência da água durante o movimento propulsivo. Com isso em mente, a utilização do ambiente aquático para o treinamento do SP dependerá do objetivo almejado pelos treinadores, considerando-se aspectos como o nível de prática do executante, o volume e a intensidade dos exercícios e as condições disponíveis, tais como a profundidade da piscina.

Title Ways to influence amateur s athletes postural stability Objectives The aim of this study is to describe the selected parameters of body composition and postural stability of the amateur s athletes (floorball players) group and to assess the efficiency of short-term intervention exercise based on senzomotor stimulation, acral coactivation therapy and plyometrics. Methods This work is a descriptive work, one part of it is the intervention. Two groups of amateur s athletes (floorball players) were examined during the study - intervention group(n = 16, average height = 178,23 cm (std 7,18), average weight = 80,04 (std 11,53), average age = 25,15 years (std3,31 )) and control group(n = 8, ave- rage height = 181,48 cm (std 5,59), average weight = 82,29 kg (std 11,20), average age = 27,07 let (2,68)). Each participant underwent the entrance measurement both on Footscan to evaluate the level of postural stability by selected parameters and on InBody 3.0 a Tanita to evaluate the level of body composition by selected parame- ters. Then the intervention group took part in the intervention exercise. After the six week intervention period underwent both groups the second measurement. The results of both measurements were evaluated, compared and statistically analyzed. Results The results showed great...

Made available in DSpace on 2016-06-02T20:18:16Z (GMT). No. of bitstreams: 1 4184.pdf: 13787055 bytes, checksum: 434e5f6a43d2ae2b1233af9adab7c137 (MD5) Previous issue date: 2012-02-23 / Financiadora de Estudos e Projetos / The aim of Study 1 was to evaluate the effects of using oral contraceptives (OC) on the hip and knee kinematics of healthy women during single-leg squat. Forty two volunteers were divided into two groups: women who had used OC (n= 21) and women who did not use OC (n= 21). The knee abduction/adduction, hip abduction/adduction and medial/lateral rotation excursions (maximum and at 75º of knee flexion) were calculated for the dominant limb during single-leg squat. No significant difference was verified between the groups regarding the maximum excursion of knee abduction (p= 0.26) or hip adduction (p= 0.10) and medial rotation (p= 0.94). When considering the knee flexion at 75º, no significant difference was verified between the groups regarding the excursion of knee abduction (p= 0.31) or hip adduction (p= 0.11) and medial rotation (p= 0.85). These results suggest that the use of OC does not influence the hip and knee kinematics during single-leg squat. As a complement, the aim of Study 2 was to evaluate the effects of using OC on the hip and knee kinematics of healthy women during anterior stair descent. Forty volunteers were divided into two groups: women who had used OC (n= 20) and 2 - women who did not use OC (n= 20). The knee abduction/adduction, hip abduction/adduction and medial/lateral rotation excursions were calculated for the dominant (supporting) limb during anterior stair descent. No significant difference was verified between the groups regarding the maximum excursion of knee abduction (p= 0.58) or hip adduction (p= 0.29) and medial rotation (p= 0.42). When considering the knee flexion at 50º, no significant difference was verified between the groups regarding the excursion of knee abduction (p= 0.92) or hip adduction (p= 0.50) and medial/lateral rotation (p= 0.19). These results suggest that the use of OC does not influence the hip and knee kinematics during anterior stair descent. The aim of Study 3 was to verify the effects of eight-week plyometric training (PT) on hip and knee kinematics and on eccentric hip and knee torques, as well as on lower limb functional performance in healthy women. Thirty-six females were divided into a training group (TG; n= 18), and a control group (CG; n= 18). Kinematic analyses of the hip and knee was carried out during the single-leg squat and the functional performance was evaluated by way of the triple hop (TH) test and the six-meter timed hop (STH) test. The eccentric hip abductor, adductor, lateral rotator and medial rotator as well as the knee flexor and extensor torques/body weight were measured using an isokinetic dynamometer. After 8 weeks, the TG showed a decrease in maximum excursion to knee abduction (p= 0.009) and in maximum excursion to hip adduction (p<0.001), as well as in the excursion to hip adduction at 75º of knee flexion (p=0.002). Moreover, the TG significantly increased the values obtained in the TH test (p=0.05) and significantly decreased those obtained in the STH test (p<0.001) after intervention. However, there was no significant change on hip and knee eccentric torques. Thus, eight weeks of PT were effective to improve hip and knee kinematics and functional performance of women in hop tests. However this was apparently not an effective method to promote strengthening of the hip and knee muscles when used alone / O objetivo do Estudo 1 foi avaliar o efeito do uso dos contraceptivos orais (CO) na cinemática do quadril e do joelho durante o agachamento unipodal em mulheres sadias. Quarenta e duas voluntárias foram divididas em dois grupos: que utilizavam (n=21) ou não (n=21) os CO. As excursões (máximas e no ângulo de 75º de flexão do joelho) em abdução/adução do joelho, em abdução/adução do quadril e em rotação medial/lateral do quadril foram verificadas durante a realização do agachamento unipodal com o membro inferior dominante. Não houve diferença significativa entre os grupos quanto à máxima excursão em abdução do joelho (p=0,26) e em adução (p=0,10) e rotação medial (p=0,94) do quadril. Quando considerado o ângulo de 75º de flexão do joelho, nenhuma diferença significativa foi verificada entre os grupos para os valores de excursão em abdução do joelho (p=0,31) e em adução (p=0,11) e rotação medial (p=0,85) do quadril. Estes achados sugerem que o uso de CO não influencia a cinemática do joelho e do quadril durante a realização do agachamento unipodal. De forma complementar, o Estudo 2 teve por objetivo avaliar os efeitos do uso de CO na cinemática do quadril e do joelho de mulheres sadias durante a descida anterior de degraus. Quarenta voluntárias foram divididas em dois grupos: que utilizavam (n=20) ou não (n=20) os CO. As excursões em abdução/adução do joelho, abdução/adução do quadril e rotação medial/lateral do quadril foram calculadas para o membro dominante durante a descida anterior de degraus. Nenhuma diferença significativa foi verificada entre os grupos para a excursão máxima em abdução do joelho (p=0,58) ou em adução (p=0,29) e rotação medial (p=0,42) do quadril. Quando considerado o ângulo de flexão do joelho de 50º, nenhuma diferença foi verificada entre os grupos para a excursão em abdução do joelho (p=0,92) ou em adução (p=0,50) e rotação medial/lateral (p=0,19) do quadril. Estes resultados sugerem que o uso de CO não influencia a cinemática do quadril e do joelho durante a descida anterior de degraus. A proposta do Estudo 3 foi verificar os efeitos do treinamento pliométrico (TP) de 8 semanas na cinemática e no torque excêntrico do quadril e do joelho, bem como sobre o desempenho funcional do membro inferior de mulheres sadias. Trinta e seis mulheres foram divididas em dois grupos: 1) grupo treinamento (GT; n=18) e 2) grupo controle (GC; n=18). A análise cinemática do quadril e do joelho foi realizada durante o agachamento unipodal e o desempenho funcional foi avaliado por meio do salto triplo unipodal (STU) e pelo salto unipodal em 6 metros cronometrado (SUC). A relação torque excêntrico abdutor, adutor, rotador lateral e rotador medial do quadril/massa corporal e o torque excêntrico flexor e extensor do joelho/massa corporal foram mensurados por meio de um dinamômetro isocinético. Após 8 semanas, o GT apresentou diminuição da excursão máxima em abdução do joelho (p=0,009) e em adução do quadril (p<0,001), bem como da excursão em adução do quadril a 75º de flexão do joelho (p=0,002). Além disso, o GT apresentou melhora no desempenho funcional para o STU (p=0,05) e para o SUC (p<0,001). Entretanto, não houve modificação significativa nos torques excêntricos do quadril e do joelho. Deste modo, o TP oito semanas foi eficiente para induzir alterações positivas de ordem cinemática e funcional nas mulheres avaliadas. Contudo, não apresentou eficiência para promover o fortalecimento dos músculos do quadril o joelho