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.