Purpose: Athletes’ force–power characteristics influence sled velocity during the skeleton start, which is a crucial determinant of performance. This study characterized force–power profile changes across an 18-month period and investigated the associations between these changes and start performance. Methods: Seven elite- and 5 talent-squad skeleton athletes’ (representing 80% of registered athletes in the country) force–power profiles and dry-land push-track performances were assessed at multiple time points over two 6-month training periods and one 5-month competition season. Force–power profiles were evaluated using an incremental leg-press test (Keiser A420), and 15-m sled velocity was recorded using photocells. Results: Across the initial maximum strength development phases, increases in maximum force (F max) and decreases in maximum velocity (V max) were typically observed. These changes were greater for talent (23.6% and −12.5%, respectively) compared with elite (6.1% and −7.6%, respectively) athletes. Conversely, decreases in F max (elite −6.7% and talent −10.3%) and increases in V max (elite 8.1% and talent 7.7%) were observed across the winter period, regardless of whether athletes were competing (elite) or accumulating sliding experience (talent). When the training emphasis shifted toward higher-velocity, sprint-based exercises in the second training season, force–power profiles seemed to become more velocity oriented (higher V max and more negative force–velocity gradient), which was associated with greater improvements in sled velocity (r = .42 and −.45, respectively). Conclusions: These unique findings demonstrate the scope to influence force–power-generating capabilities in well-trained skeleton athletes across different training phases. To enhance start performance, it seems important to place particular emphasis on increasing maximum muscle-contraction velocity.
Steffi L. Colyer, Keith A. Stokes, James L.J. Bilzon, Danny Holdcroft and Aki I.T. Salo
Steffi L. Colyer, Keith A. Stokes, James L.J. Bilzon, Marco Cardinale and Aki I.T. Salo
An extensive battery of physical tests is typically employed to evaluate athletic status and/or development, often resulting in a multitude of output variables. The authors aimed to identify independent physical predictors of elite skeleton start performance to overcome the general problem of practitioners employing multiple tests with little knowledge of their predictive utility.
Multiple 2-d testing sessions were undertaken by 13 high-level skeleton athletes across a 24-wk training season and consisted of flexibility, dry-land push-track, sprint, countermovement-jump, and leg-press tests. To reduce the large number of output variables to independent factors, principal-component analysis (PCA) was conducted. The variable most strongly correlated to each component was entered into a stepwise multiple-regression analysis, and K-fold validation assessed model stability.
PCA revealed 3 components underlying the physical variables: sprint ability, lower-limb power, and strength–power characteristics. Three variables that represented these components (unresisted 15-m sprint time, 0-kg jump height, and leg-press force at peak power, respectively) significantly contributed (P < .01) to the prediction (R 2 = .86, 1.52% standard error of estimate) of start performance (15-m sled velocity). Finally, the K-fold validation revealed the model to be stable (predicted vs actual R 2 = .77; 1.97% standard error of estimate).
Only 3 physical-test scores were needed to obtain a valid and stable prediction of skeleton start ability. This method of isolating independent physical variables underlying performance could improve the validity and efficiency of athlete monitoring, potentially benefitting sport scientists, coaches, and athletes alike.