The Application of Isokinetic Testing to Understand Factors Predicting Performance in the 100m, 400m, Long Jump and High Jump

Strength or force and power in athletics have been identified as important factors linked to, and in some situations determining performance (1,2,3,4,5). Power is defined as the mechanical work done in a specified period of time (1,3,6) or the product of force by velocity (3,6) and as the ability of the human neuromuscular system to produce the greatest possible impulse in a given period of time (2). Strength is defined as neuromuscular force exerted against movable and immovable objects or as peak force or torque generated by voluntary muscular contractions. Strength and force are often used interchangeably in sport (6). Research (1) examined the power in sprinting and concluded that high power production was characteristic of high performance male and female sprinters based on research of indoor and outdoor competitions, especially the role of hip and knee flexors and extensors. Research by Schmidtbleicher ((2) indicated that movements with a duration of less than 0.25 seconds the maximal rate of force development and the initial rate of force development are the main factors that influence performance. The maximal rate of force development is analogous to power or force time velocity construct. Sprint running, high jump and long jump events require the use of fast stretch shortening cycle actions (ground contact phases) that last from 0.10 to 0.25 seconds, which would indicate that factors as power development and torque acceleration energy (TAE) should be important and predictive factors of performance in sprint and jump events. Torque acceleration energy is defined as the amount of energy expended (work performance) in the first 0.125 seconds of torque production in a dynamic contraction.  TAE is indicative of muscular “explosiveness” and the greater the energy generated in this short timeframe the greater the TAE (7). According to Schmidtbleicher (2), Wilson (3) and Ackland et al., (6) the quality of power production in the stretch-shortening cycle is essentially dependent on the structure of the innervation patterns and the training state of the tendomusclular system in terms contractile and elastic (energy storing) abilities. It must be emphasised the gains in strength training will not necessarily be reflected in in enhanced power production and transfer or be the best predictors of sprint and jump performances or where movements are very fast and with limited time to produce force. Isokinetic testing has displayed some variable relationships with different sports, such as the importance of high peak torque production for jumpers (4) whereas other research has indicated minimal relationship of isokinetic leg extension/flexion performance at 60°s-1 and 300°s-1 with 5m, 10m and 30m sprint acceleration performance in a sample of semi and professional adult male Rugby League players (5). A number of research problems have been identified based on previous research using isokinetic testing to assess the correlation of force, work and power with sprint and jump performances. These include limited sample sizes of youth, high performance and non-athletic populations and not evaluated a range of ability levels to assess if athletes require high levels of force, power and TAE as they may relate to different athletic events, such as the 100m, 400m, long jump and high jump events. Statistical techniques utilised in previous research were based mainly on methods of association, such as correlation and not predictive statistical modelling, such as multiple linear regression that can assess the prediction of competition performance based on laboratory derived measures as peak torque, work, power, torque/weight, power/weight and TAE that can be derived validly, reliably, accurately and objectively. The research aims were to more completely understand the relationship between isokinetic measures for leg extension/flexion across three isokinetic speeds (60°s-1,  180°s-1 and  300°s-1) and track and field performance in the 100m, 400m, long jump and high jump in young adult male and female athletes.  Quantifying the multivariate contributions of peak torque, work, power, torque/weight, power/weight and TAE to each event. The findings will enable a more systematic approach for athletes, coaches and sport scientists to design and monitor training programs and athlete adaptations to training and assess if isokinetic testing will enable a new dimension to identify potential talent in talent identification programs?