The effects of external loading on jumping mechanics have been extensively investigated;
however, review of the body of knowledge revealed a number of methodological issues,
as well as a common omission of key mechanical theory, with limited studies
investigating the effects of changing the position of the external load. Therefore, the
primary aim of this thesis was to investigate the effects of changing the position of the
external load and training status on system centre of mass and lower limb joint mechanics
during countermovement jumping, with a particular emphasis on power output. Section
3 (Mundy, Lake, Carden, Smith, & Lauder, 2016a) established that the force platform
method and the combined method cannot be used interchangeably within practice for
measuring power output, and argued that the force platform method should be adopted as
the criterion method. Using the force platform method, section 4 (Mundy, Smith, Lauder,
& Lake, 2016b) established that the effects of barbell loading on system centre of mass
mechanics reported are often overemphasised, and it was argued that investigating the
complex interaction between the underpinning force, temporal and spatial components is
of interest to practitioners. Section 5 demonstrated that practitioners may overcome the
constraints of barbell loading by changing the position of the external load to arms’ length
using a hexagonal barbell, which facilitated greater system centre of mass and lower limb
joint mechanics in strength-power trained athletes. However, as the effects of external
load have been posited to be population specific, section 6 demonstrated that regardless
of the magnitude of the external load, strength-power trained athletes produced
significantly greater hip joint peak power outputs than their recreationally trained
counterparts. As such, the findings of the thesis support the hypothesis that practitioners
should prescribe the position of external loading that maximise hip joint peak power
output. In conclusion, this thesis has not only made significant steps towards providing a
standardised method of measuring power output, but it has also offered a revealing insight
into the effects of training status, as well as the effects of changing the position and
magnitude of the external load on system centre of mass and lower limb joint mechanics
during countermovement jumping.