The Effect of Stirrup Length on Impact Attenuation and Its Association With Muscle Strength

Abstract

Horseback-riders have a high prevalence of low back injuries, which may be related to the repetitive low back impacts experienced in riding. The purposes of this study were to quantify the effect of 3 stirrup lengths and 2 riding styles on the peak acceleration experienced by the rider and the association between the peak acceleration and the rider's different elements of muscle strength. Thirteen female riders performed a sitting or rising trot at each of the 3 stirrup lengths (2-point length, mid-seat length, or dressage length), while the acceleration of the tibia, sacrum, seventh cervical vertebra (C7), and head were collected. Subjects completed a push-up, a vertical jump, and 4 core exercises to assess upper-body strength, lower-body strength, and core endurance, respectively. Peak acceleration of the sacrum, C7, and head were generally lower in the standing phase of the rising trot compared with the sitting phase of either the sitting or rising trot, particularly at the shortest stirrup length. Peak acceleration of the sacrum, C7, and head decreased as the stirrup length was shortened in the standing phase of the rising trot. Canonical correlations showed nonsignificant correlations between strength measurements and peak acceleration. Riding with more weight supported through the legs with a short stirrup length may decrease low back impacts and their associated injury risk. Technique training is likely needed to encourage riders to use lower-body and core strength for impact attenuation.

Effects of saddle tilt and stirrup length on the kinetics of horseback riders

“…More recent studies have demonstrated that the key to reducing back pain is achieving an adequate attenuation of the shockwaves transmitted from the horse to the lumbopelvic hip complex through the saddle ( Cejudo, Ginés-Díaz & Sainz de Baranda, 2020 ). It has been observed that showjumpers tend to select shorter stirrup lengths in order to better absorb the shocks generated when landing jumps ( Pugh & Bolin, 2004 ), and it has been suggested that riders with back pain can counteract it with lower stirrup lengths ( Keener et al, 2020 ), but no evidence has yet been provided to clearly describe how longer or shorter stirrups influence shock attenuation. Our data support such observations since it shows an optimised shock attenuation and an increase on stirrup forces with shorter stirrups.…”

“…For instance, achieving saddle tilt with correction saddle pads will not lead to the same results as modifying the saddle design so that the panels remain aligned while only the seat tilts for the rider. This is why individualization of saddle setup must be performed with care and by using the general agreements on saddle tilt and stirrup lengths proposed elsewhere ( Kotschwar, Baltacis & Peham, 2010 ; Andrews-Rudd et al, 2018 ; Farmer-Day et al, 2018 ; Keener et al, 2020 ; Roost et al, 2020 ) only as a starting point. From that starting point, one must reach the optimal setup through trial and error.…”

“…During the last decade, authors have gained interest on how the saddle configuration affects the rider’s performance. Keener et al (2020) investigated how three different stirrup lengths affected peak acceleration on the rider’s back, concluding that shorter stirrups had the potential to reduce the impacts received by the rider.…”

Asymmetry and Tightness of Lower Limb Muscles in Equestrian Athletes: Are They Predictors for Back Pain?

“…With regard to spinal misalignments, Auvinet [28] reported an incidence of lumbar hyperlordosis of 72% for professional EAs and Ginés-Díaz et al [17] displayed hyperlordosis in standing position and hyperkyphosis in slump sitting and trunk flexion positions in EAs. The LBP is caused by high, repetitive, and multiplanar propulsion forces of the horse that are absorbed through the EA's body [29][30][31]. A misaligned spine increased and disproportionately distributed the mechanical forces transmitted by the horse to the pelvic hip complex and lumbar spine of rider [17,19,31].…”

“…Show jumping riders displayed hip and knee flexion in the basic posture by the shortest use of the horse stirrup; this position allows the rider a greater impulse in the jump and a better cushioning in the horse landing after overcoming the obstacle [1,36]; however, this rider position causes pelvis retroversion and reduction of lumbar lordosis [3,36]. On the contrary, the use of horse stirrups with a longer length by dressage riders allows a more vertical position of the rider [30,36]. In this regard, Gandy et al [13] suggested that the use of different lengths in the stirrups helps to adopt a pelvis and spine disposition within the normal ranges in EAs.…”