Modulation of joint moments and work in the goat hindlimb with locomotor speed and surface grade

Abstract

SUMMARYGoats and other quadrupeds must modulate the work output of their muscles to accommodate the changing mechanical demands associated with locomotion in their natural environments. This study examined which hindlimb joint moments goats use to generate and absorb mechanical energy on level and sloped surfaces over a range of locomotor speeds. Ground reaction forces and the three-dimensional locations of joint markers were recorded as goats walked, trotted and galloped over 0, +15 and −15deg sloped surfaces. Net joint moments, powers and work were estimated at the goatsʼ hip, knee, ankle and metatarsophalangeal joints throughout the stance phase via inverse dynamics calculations. Differences in locomotor speed on the level, inclined and declined surfaces were characterized and accounted for by fitting regression equations to the joint moment, power and work data plotted versus non-dimensionalized speed. During level locomotion, the net work generated by moments at each of the hindlimb joints was small (less than 0.1Jkg -1 body mass) and did not vary substantially with gait or locomotor speed. During uphill running, by contrast, mechanical energy was generated at the hip, knee and ankle, and the net work at each of these joints increased dramatically with speed (P<0.05). The greatest increases in positive joint work occurred at the hip and ankle. During downhill running, mechanical energy was decreased in two main ways: goats generated larger knee extension moments in the first half of stance, absorbing energy as the knee flexed, and goats generated smaller ankle extension moments in the second half of stance, delivering less energy. The goatsʼ hip extension moment in mid-stance was also diminished, contributing to the decrease in energy. These analyses offer new insight into quadrupedal locomotion, clarifying how the moments generated by hindlimb muscles modulate mechanical energy at different locomotor speeds and grades, as needed to accommodate the demands of variable terrain.

Modulation of work and power by the human lower-limb joints with increasing steady-state locomotion speed

“…It is interesting to compare our data for human running with equivalent data from studies that have investigated the effect of increasing trotting and/or galloping speeds on hindlimb joint mechanics for quadrupedal terrestrials, such as horses (Clayton et al, 2002;Dutto et al, 2006), goats (Arnold et al, 2013) and dogs (Colborne et al, 2006). While the mechanical behavior of a distal joint such as the ankle (or tarsus) is similar for quadrupeds and humans (i.e.…”

“…a period of W À j during early stance followed by a period of W þ j during late stance, both of which increase in magnitude with faster speed), distinct differences are evident in the mechanical behavior of a proximal joint such as the hip, especially during stance. For quadrupeds, power is generated and positive work is done by the hindlimb hip for the majority of stance, although this profile appears more accentuated for horses (Dutto et al, 2006) and dogs (Colborne et al, 2006) than for goats (Arnold et al, 2013). As trotting or galloping speed becomes faster, peak hip power generation during stance increases substantially (Colborne et al, 2006;Dutto et al, 2006;Arnold et al, 2013); thus, the hip extensors are important muscles for powering quadrupedal locomotion.…”

“…For quadrupeds, power is generated and positive work is done by the hindlimb hip for the majority of stance, although this profile appears more accentuated for horses (Dutto et al, 2006) and dogs (Colborne et al, 2006) than for goats (Arnold et al, 2013). As trotting or galloping speed becomes faster, peak hip power generation during stance increases substantially (Colborne et al, 2006;Dutto et al, 2006;Arnold et al, 2013); thus, the hip extensors are important muscles for powering quadrupedal locomotion. In contrast, for humans, the hip generates power during early stance before absorbing a larger amount of power in late stance (Fig.…”

Integrating gastrocnemius force-length properties,in vivoactivation, and operating lengths reveals howAnolisdeal with ecological challenges

“…With the pes in this location, propulsion is characterized by rapid extension of the knee and ankle before the pes abducts and falls away from the sides of the perch to begin swing phase. This contrasts with the broad perch, where the entire foot, including digits, is in an orientation that allows knee and ankle extension to contribute significantly to forward propulsion, as is well recognized in terrestrial animals (Brinkman, 1980;Gregersen et al, 1998;Russell and Bels, 2001;McGowan et al, 2005McGowan et al, , 2008Arnold et al, 2013). The greater reliance on ankle extension for propulsion on the broad surface may explain the shifts in gastrocnemius with changes in perch diameter.…”

Patolojik yürüme

“…[16] Ayak bileği kaynaklı yürüme bozuklukları plantar fleksiyonda artmaya neden olan patolojiler (parmak ucu yürüyüş) ve dorsifleksiyonda artmaya neden olan patolojiler (topuk yürüyüşü) olarak sınıflanabilir.…”