|dc.description.abstract||It is a common belief in bobsleigh that the push-start is a vital aspect of
successful performance. Therefore, British Bobsleigh places a heavy
emphasis on the use of field-based performance testing to assist with both
athlete monitoring and talent identification. There is a general lack of published
academic literature in bobsleigh. Thus, limited evidence exists confirming the
importance of the push-start, as well as validating the field-based performance
tests used by British Bobsleigh. The aim of this thesis was to validate and
develop the core principles and scientific underpinnings of squad monitoring
and talent identification specific to ‘brake-men’/’brake-women’ push-start
performance in bobsleigh.
Study 1 examined the relationship between the push-start and finish time
across elite bobsleigh competitions for 2-man, 4-man and female event
formats, across multiple tracks and over multiple on-ice seasons. The study
demonstrated most tracks on the elite bobsleigh circuit to be either push-start
dominant or moderately influenced by the push-start (common variance ≥
10%). Thus, it highlighted the value of evaluating and developing push-start
performance in British Bobsleigh athletes.
Studies 2 and 3 investigated the current performance testing practices of
British Bobsleigh, used in both talent identification and squad monitoring.
Study 2 investigated the predictive validity of the ‘evaluation test’ used by
British Bobsleigh to assess whether the whole test battery, as well as individual
tests included within it relate to the bobsleigh push-start. Although this study
confirmed the predictive validity of ‘evaluation test’ total points to assess
athletes push-start capabilities (r = -0.86 to -0.94), completion of the entire
testing battery proved somewhat unnecessary. This largely manifested from
the major finding of this study that confirmed that the roll-bob push test could
be used as a reliable (CV = 0.7 to 1.7%) and valid (r = 0.83 to 0.98) predictor
of push-start performance. Subsequent attempts to explain push-start
performance using only the general performance tests included within the
‘evaluation test’, highlighted the importance of body mass and 30 m sprint time.
However, the explained variance in male push-start performance (55 %),
highlighted a clear need to examine other performance qualities beyond those
in the current British Bobsleigh ‘evaluation test’. Study 3 explored the reliability,
discriminative validity and predictive validity of the British Bobsleigh ‘Keiser
Squat Test’. The findings of the study confirmed the reliability of the test
protocol (CV = 6 to 10 %), as well as reporting very large to near perfect
predictive ability for the female push-start (r = -0.86 to -0.96). Despite this, the
strength of the prediction was only moderate in male athletes (r = -0.30 to -
0.47) and the test could only distinguish between world class performance
(WCP) and national development (ND) male athletes at a moderate load.
Subsequently, other performance tests outside the current practices of British
Bobsleigh but identified from the winter sliding sport, strength and power
diagnostic and sprinting literature were explored.
Study 4 investigated the validity of vertical and horizontal jump test metrics,
completed under both bilateral and unilateral conditions, to predict push-start
performance. The major findings were that horizontally oriented tests (e.g.
standing long jump (SLJ)) may represent better push-start predictive ability
than vertically oriented tests (e.g. the countermovement jump (CMJ) and
‘Keiser Squat Test’). Also, maximising an athlete’s unilateral facilitation, as well
as minimising any between limb asymmetries appears to be beneficial for
push-start performance (r = 0.67 to 0.88). Thus, the addition of unilateral SLJ
peak horizontal force, bilateral index and asymmetry index to the British
Bobsleigh ‘evaluation test’, may help to account for some of the unexplained
variance in push-start performance identified in study 2.
Study 5 explored the discriminative validity and predictive validity of sprint
force-velocity profiling for the bobsleigh push-start. Also, the study investigated
the influence of a 16-week pre-season training phase on bobsleigh athlete’s
sprint force-velocity mechanical profiles and associated changes in push-start
performance. The sprint force-velocity mechanical variables Pmax, relative
Pmax, V0 and Vopt were all shown to provide discriminative validity for the
bobsleigh push-start. However, of these variables, Pmax demonstrated the
strongest correlation with push-start performance (r = 0.80). At a group level,
the findings of the study detected training induced improvements in push-start
performance, sprint speed and Pmax (absolute & relative), with the largest
group-based improvements observed in absolute Pmax. This was reflected with
all athletes making worthwhile gains in Pmax, however this did not always
translate to improvements in push-start performance on an individual level.
Thus, there may be other factors important for push-start performance beyond
those measured in this study.
To conclude, the push-start has a moderate to large influence on performance
at most tracks on the elite bobsleigh circuit. The roll-bob push test provides a
reliable and valid measure to quantify the push-start capabilities of bobsleigh
athletes. When considering the key underpinning determinants of push-start
performance in bobsleigh, this thesis highlighted the importance of body mass,
sprinting speed (30 m sprint time), sprinting maximal mechanical power (sprint
force-velocity profiling), unilateral horizontal force production (unilateral SLJ)
and power production under moderate external loads (‘Keiser Squat Test’).
Thus, practitioners working in bobsleigh should consider these key qualities
when designing future squad monitoring and talent identification performance
testing batteries and designing training programmes.||en_US