Biomechanical demands of the 2-step transitional gait cycles linking level gait and stair descent gait in older women

Stair descent is an inherently complex form of locomotion posing a high falls risk for older adults, specifically when negotiating the transitional gait cycles linking level gait and descent. The aim of this study was to enhance our understanding of the biomechanical demands by comparing the demands of these transitions. Lower limb kinematics and kinetics of the 2-step transitions linking level and descent gait at the top (level-to-descent) and the bottom (descent-to-level) of the staircase were quantified in 36 older women with no falls history. Despite undergoing the same vertical displacement (2-steps), the following significant (p<.05) differences were observed during the top transition compared to the bottom transition: reduced step velocity; reduced hip extension and increased ankle dorsiflexion (late stance/pre-swing); reduced ground reaction forces, larger knee extensor moments and powers (absorption; late stance); reduced ankle plantarflexor moments (early and late stance) and increased ankle powers (mid-stance). Top transition biomechanics were similar to those reported previously for continuous descent. Kinetic differences at the knee and ankle signify the contrasting and prominent functions of controlled lowering during the top transition and forward continuance during the bottom transition. The varying musculoskeletal demands encountered during each functional sub-task should be addressed in falls prevention programmes with elderly populations where the greatest clinical impact may be achieved. Knee extensor eccentric power through flexion exercises would facilitate a smooth transition at the top and improving ankle plantarflexion strength during single and double limb stance activities would ease the transition into level gait following continuous descent

Sagittal plane joint kinetics during stair ascent in patients with peripheral arterial disease and intermittent claudication

Stair negotiation poses a substantial physical demand on the musculoskeletal system and this challenging task can place individuals at risk of falls. Peripheral arterial disease (PAD) can cause intermittent claudication (IC) pain in the calf and results in altered gait mechanics during level walking. However, whether those with PAD-IC adopt alternate strategies to climb stairs is unknown. Twelve participants with PAD-IC (six bilateral and six unilateral) and 10 healthy controls were recruited and instructed to ascend a five-step staircase whilst 3D kinematic data of the lower-limbs were recorded synchronously with kinetic data from force plates embedded into the staircase on steps two and three. Limbs from the unilateral group and both limbs from the bilateral claudicants were categorised as claudicating (N = 18), asymptomatic (N = 6) and control (N = 10). Claudicants walked more slowly than healthy controls (trend; P = < 0.066). Both claudicating- and asymptomatic-limb groups had reduced propulsive GRF (P = 0.025 and P = 0.002, respectively) and vertical GRF (P = 0.005 and P = 0.001, respectively) compared to controls. The claudicating-limb group had a reduced knee extensor moment during forward continuance (P = 0.060), ankle angular velocity at peak moment (P = 0.039) and ankle power generation (P = 0.055) compared to the controls. The slower gait speed, irrespective of laterality of symptoms, indicates functional capacity was determined by the limitations of the claudicating limb. Reduced ankle power generation and angular velocity (despite adequate plantarflexor moment) implies velocity-dependent limitations existed in the calf. The lack of notable compensatory strategies indicates reliance on an impaired muscle group to accomplish this potentially hazardous task, highlighting the importance of maintaining plantarflexor strength and power in those with PAD-IC

Effects of Wider Step Width on Knee Biomechanics in Obese and Healthy-Weight Participants During Stair Ascent

An increased likelihood of developing obesity-related knee osteoarthritis may be associated with increased peak internal knee abduction moment. Increases in step width may act to reduce this moment. This study focused on how step width influenced the knee joint during stair ascent by healthy and obese participants. Participants ascended stairs while walking at their preferred speed and under one of two step width conditions – preferred and increased. Obese participants experienced greater mediolateral and vertical ground reaction forces (GRFs), as well as increased peak knee extensor moments and push-off peak internal knee adduction moments. The findings of this study indicate that when step width increases, obese participants will experience a disproportionate increase in Loading-response and push-off response peak mediolateral GRF, push-off peak knee adduction moments, and peak knee adduction angle compared to healthy participants. When normalized to lean body mass, obese participants also had greater increases in peak knee extension moments under the increased step width condition. Participants in each group experienced decreased in loading-response peak vertical GRF, loading-response peak knee abduction moment, peak knee internal rotation moment, knee extension range of motion, and knee abduction range of motion, and increased loading-response and push-off response peak mediolateral GRF, push-off peak knee adduction moment, peak knee external rotation moment, peak knee abduction angle, and knee internal rotation range of motion. This study provides important information regarding differences in knee joint biomechanics during stair ascent between obese and healthy populations

Chapter 9: Biomechanics

Biomechanics is a discipline. A discipline deals with understanding, predicting, and explaining phenomena within a content domain, and biomechanics is the study of the human body in motion. By applying principles from mechanics and engineering, biomechanists are able to study the forces that act on the body and the effects they produce (Bates, 1991). Hay (1973) describes biomechanics as the science that examines forces acting on and within a biological structure and the effects produced by such forces, whereas Alt (1967) describes biomechanics as the science that investigates the effect of internal and external forces on human and animal bodies in movement and at rest. Each of these definitions describes the essential relationship between humans and mechanics found in biomechanics