(5) RELATIONSHIP BETWEEN THE LEG/BACK DYNAMOMETER AND CONVENTIONAL DEADLIFT IN RESISTANCE TRAINED INDIVIDUALS: A PILOT ANALYSIS

Purpose: The conventional deadlift (CD) is a popular exercise for assessing muscular strength. In addition to the general public, athletic and tactical populations may use the conventional deadlift to assess an individual’s strength and assist with program design. However, maximal strength testing may be time-consuming, fatiguing, require multiple pieces of equipment, and not be appropriate for certain individuals (e.g., untrained individuals). A leg/back dynamometer (LBD) is an isometric strength test that may be less stressful and time-consuming and offers an efficient approach to strength testing. The purpose of this study was to assess the relationship and predictive ability that the LBD (isometric strength) has with 1RM CD (dynamic strength) in resistance-trained individuals. Methods: This current research was part of a larger study that examined the relationship of the LBD with the CD and Hexagonal Bar Deadlift (HBD). Only the conventional deadlift was considered for this analysis. Data from 15 resistance trained individuals (8 male, 7 female) were analyzed. Subjects participated in three separate sessions, where they performed a 1RM HBD, 1RM CD, and LBD test on three separate days. The highest 1RM achieved was recorded for the CD. Measurements for the LBD were the best and average of three trials, taken to the nearest kilogram. Relative values for both tests were also considered. Correlations and bivariate regressions derived relationships between LBD values and 1RM CD (p< 0.05). Results: The results showed a significant and strong correlation between the maximum and average LBD and 1RM CD (r = 0.709 - 0.829, p < 0.05). The 1RM CD was predicted by maximum (explained variance = ~46%) and average (explained variance = ~56%) LBD (Figure 1). Relative 1RM CD was predicted by relative LBD max (explained variance = ~57%) and average (explained variance = 66.4%). Conclusions: Isometric maximal strength (LBD) was strongly related to dynamic maximal strength (CD). Although not as strong, the results showed that the LBD could predict 1RM CD. The average of both absolute and relative values on the LBD best predicted absolute and relative 1RM CD, respectively. The average of multiple trials on the LBD may be a better predictor for dynamic strength measured by the CD than the highest LBD value. Where appropriate, isometric strength tests may be a useful substitute for 1RM tests. Practical Applications: Isometric strength tests, such as the LBD, could be a safe alternative to 1RM testing to track individual progress, reduce residual fatigue, and decrease time spent working up to a 1RM during testing. Since an isometric strength test is less fatiguing than a 1RM test, multiple trials may be considered for strongest predictive ability. The moderate explained variance could be due to the small sample size, position on the thigh of the LBD, or the difference in grips and grip length between the CD and LBD. Acknowledgements: None