Abstract
Strength training forms an integral part of the preparation of elite athletes from many sports. Despite the popularity of strength training, little is known about the relationships between strength and sporting performance. Rowing provides an excellent example of a sport where the limitations of conventional isometric, isokinetic and isoinertial strength research have led to considerable confusion regarding the role of strength in determining performance. The dynamic strength levels of rowers have not been published in the scientific literature. Therefore the primary aim of the research presented in this thesis was to investigate the influence of dynamic strength on rowing performance. Two comprehensive experimental studies were undertaken. The first used correlation and regression analyses to determine the relationships between dynamic squat jump and bench pull strength levels and rowing performance in male international level single scullers (n = 12) and sweep oar rowers (n = 24). Maximum dynamic strength (MDS) in the bench pull accounted for the majority of the variance in predicting both 5000 m on-water (R2 = 0.67) and 2000 m ergometer (R2 = 0.90) performance time in the single scull group. However, in the sweep oar group squat jump MDS accounted for the majority of the variance in predicting on-water time (R2 = 0.72), while squat jump maximum rate of force development (MRFD) accounted for the majority of the variance in predicting ergometer time (R2 = 0.63). The dynamic strength data were compared between the single scullers and sweep oar rowers using a one-way analysis of variance (ANOVA) on one factor (rowing category). Results (presented as x ±SEM) indicated that, compared to the single scullers, the sweep oar rowers recorded significantly higher squat jump MDS (150.11 kg ±2.23 vs. 125.48 kg ±5.77), MDS when expressed as a function of body mass [RelMDS (1.75 ±0.02 vs. 1.57 ±0.05)], MRFD (24239 N.s-1 ±403 vs. 16849 N.s-1 ±1952) and bench pull MRFD (21676 N.s-1 ±1227 vs. 16475 N.s-1 ±1713) levels than the single scullers. Peak oxygen uptake ( ) and maximum post exercise blood lactates (bLa) were also incorporated into multiple regression analyses to test the robustness of the predictive qualities of dynamic strength variables. These data indicated that despite (L.min-1) having strong correlations with ergometer time (r = -0.94) in the single scullers, and both on-water (r = -0.75) and ergometer time (r = -0.84) in the sweep oar group, it was not the highest individual contributor in multiple regression equations. One exception was ergometer time in the sweep oar group (R2 = 0.64). Analysis also involved a comprehensive biomechanical kinematic and kinetic on-water and rowing ergometer stroke analysis. The relationships between dynamic strength and biomechanical stroke parameters were determined using a combination of correlation and step-wise multiple regression. Analyses indicated that the majority of relationships between dynamic strength variables and on-water stroke biomechanics were weak (R2 between 0.2 and 0.3). However, the power of the relationships increased when dynamic strength variables were correlated with biomechanical ergometer stroke variables (R2 > 0.5). Results suggested differences in the roles of dynamic strength between single scullers and sweep oar rowers. It was evident that body mass (BM) has a strong influence on 5000 m on-water and 2000 m ergometer time trial performance in international level oarsmen (r = -0.63 and -0.93 for the scullers and r = -0.93 and -0.83 for the sweep oar rowers). Accordingly, the second part of this thesis used an intervention study (6 male and 6 female national level single scullers) to determine whether increases in dynamic strength through specific weight training resulted in concomitant changes in rowing performance. Results from pre testing were used in correlation and regression analyses to test whether the relationships between dynamic strength and rowing performance continued in a group of more heterogeneous rowers. The majority of relationships followed similar trends to those reported for the international scullers. To test for possible cause-effect relationships the national level scullers were divided into two groups (matched-pairs) prior to an 8 week intervention period. The dynamic strength training group [DST group (n = 6)] underwent specific strength training designed to improve bench pull and squat jump MDS and MRFD levels, while the traditional strength trained group [TST group (n = 6)] completed a program of traditional maximal strength training involving heavy loads and low repetitions. Both groups continued with their normal rowing training during the period under investigation. Effect size (ES) analyses indicated that bench pull MDS and squat jump MDS and MRFD increased from pre to post testing in the DST group only. ES analyses indicated a moderate improvement in on-water time trial performance in the DST group, although a clear causal relationship between this variable and changes in dynamic strength was not apparent. In contrast, there were probable causal relationships between bench press MDS and the maximum horizontal velocity of the oar handle during the drive phase, squat jump MDS and the maximum hip extension velocity during the drive phase, and squat jump MRFD and the maximum horizontal velocity of the seat during the drive phase. Squat jump MDS and MRFD both had apparent causal relationships with the maximum muscle moments about the hip during the drive phase. Conclusions from these studies indicate that dynamic strength testing provides important information for the training regimens of national and international level rowers. Although there were no simple causal relationships between dynamic strength and rowing performance time, improvements in dynamic strength variables through specific conditioning appeared to affect several biomechanical stroke parameters. In homogeneous populations of elite single scull and sweep oar rowers, squat jump and bench pull dynamic strength levels have a stronger influence on rowing performance than . Rowing weight training should concentrate on the development of leg and upper body MDS rather than following the current trend of maximal strength and MRFD training. This thesis has increased understanding about the specific strength requirements of rowers and has reduced confusion about the role of strength on rowing performance.