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Balasekaran, Govindasamy
Issue Date: 
Isometric strength training (IST) has been shown to be less fatiguing, results in greater improvement in joint angle specific strength and musculotendinous stiffness as compared to dynamic strength training. However, there is a lack of study investigating the effects of IST on the performance of sports related movement in the current literature. Therefore, the aim of this series of studies was to investigate on the effects of IST on various sports related movement performance.

Study 1 compared the effects of two IST loading methods on strength adaptations, sprinting and jumping performances in team sport athletes. Athletes were randomly assigned to control (CON), non-sustained contraction isometric training (EIST) or 3-s sustained contraction isometric training (SIST) group. All groups performed 12 sessions of training with similar strength training program over six weeks. However, only the two IST group performed isometric squat exercise, with either 1-s or 3-s sustained contraction for each repetition. Both IST groups improved strength and jump measures. Sprint performance was improved only in SIST. No differences were observed between the magnitudes of improvement for all measures between the two IST groups. However, significant difference in magnitude of improvement for sprinting and strength measures was observed between Con and SIST only. This study showed that the 3-s sustained contraction method is a more effective loading method for IST.

Study 2 compared the effects of IST and plyometric training (PT) on endurance running performance. Runners were randomly assigned to Con, IST or PT group. All groups attended two intervention training sessions per week for six weeks. Con performed three callisthenic exercises, IST performed two multi-joint isometric exercises and PT performed three plyometric exercises. Significant improvement in 2.4 km run time trial, peak running velocity and countermovement jump performances were observed in both PT and IST. However, running economy and isometric mid-thigh pull peak force were improved in IST only. Con did not result in any significant change in all variables. This study showed that performing IST resulted in similar level of improvement in endurance running performance indicators as performing plyometric training.

Study 3 compared the effects of traditional strength training (TRD) and the inclusion of IST on sprint kayaking performance in well trained sprint kayakers. Athletes were randomly assigned to TRD and IST group. Both groups performed 12 sessions of training with similar strength training program over six weeks. However, half the volumes for dynamic squat, bench press and prone bench pull were replaced by isometric mode for each exercise in IST. Mean power for 200-m ergometer kayaking was improved in both groups, but IST showed a larger effect. IST also showed improvement in all isometric squat, bench press and prone bench pull measures while TRD only showed improvement for isometric prone bench pull measures at 120o elbow angle. The results from this study showed that the inclusion of IST resulted in greater improvement in sprint kayaking performance and strength adaptations.

Altogether, the three studies showed that IST is effective in enhancing muscular strength, sprinting, jumping running and sprint kayaking performances. Therefore, IST can be included as part of athletes’ training for the purpose of improving strength and dynamic performances. Further, based on the results obtained from this series of studies, it is recommended to perform IST twice a week for 3 sets and 5 repetitions per set with rapid and maximal contraction sustained for 3 s per repetition.
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RA781.2 Lum
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Appears in Collections:Doctor of Philosophy (Ph.D.)

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