Week 6 Cue cards

mobility and gait as a foundation for independence

• Mobility/gait is critical for independence and quality of life; even small mobility gains can maintain home living and daily function.

• After injury or surgery (e.g., stroke), early mobility goals often focus on standing up, transferring to a wheelchair or toilet, and taking a few steps, which supports preserving upper-limb function and overall independence at home.

• Gait is a highly automated, complex motor skill achieved via cyclic activation of left and right limbs with synergistic muscle activity to produce an efficient pattern.

• Key components of mobility in daily life include progression, which involves moving the body forward in the intended direction.

  • Initiation and termination: starting and stopping movement (e.g., waiting at a crosswalk).

  • Stability: maintaining posture and controlling the centre of mass within the base of support.

  • Adaptation: adjusting gait to meet environmental demands (e.g., stepping onto a curb, avoiding a car running a red light).

• Throughout a walk, the base of support (BoS) changes: during swing, BoS is basically the stance foot; during double-support, BoS is the region between both feet. The centre of mass must be kept within BoS to stay upright.

• Environmental demands require gait adaptation (e.g., uneven surfaces, curbs, traffic).

why focus on older adults?

• Falls are a major issue and a leading cause of injury-related death in adults >65.

• Mortality related to hip fracture after falls is high:

  • With surgical repair, 12-month mortality ~ 21%.

  • With conservative (non-surgical) management, 12-month mortality ~ 70%.

• These mortality risks are linked to inactivity during recovery, decreased weight-bearing, cardiovascular deconditioning, and muscle wasting.

• Older adults often avoid risky environments to prevent further decline, which can itself contribute to reduced mobility and health risk.

• Aging involves both primary and secondary changes:

  • Primary aging: intrinsic biological changes (gene expression shifts, telomere shortening, hormonal changes) that influence gait.

  • Secondary aging: environmental and lifestyle factors (nutrition, exercise, stress, comorbidities such as diabetes, peripheral vascular disease, stroke) that can modulate gait and mobility trajectories.

• Clinically, it is important to differentiate primary aging processes from secondary, potentially modifiable factors when planning interventions.

spatial-temporal characteristics of gait in ageing

• Aging is associated with slower walking speed, shorter step length, reduced cadence, and longer double-support time.

• These four features are interrelated: slowing speed often coincides with shorter steps and lower cadence, which increases the time both feet are in contact with the ground.

• Sex differences: The effects on spatial-temporal measures may be more pronounced in females, potentially linked to hormonal changes (e.g., menopause) and differences in muscle properties/size with aging.

• Comfort strategies to improve stability include: Increased step width (base of support) to enhance stability.

  • Greater toe-out angle to widen BoS and improve stability.

kinematics of gait in ageing

• Head and trunk: the head becomes a less mobile, more rigid segment; movements in vertical and lateral directions decrease as people try to keep the centre of mass within BoS (a more “stable” profile).

• Lower limb joint angles: reduced hip, knee, and ankle flexion observed in older adults; this reduces foot clearance during swing and can increase tripping risk.

• Ankle mechanics: reduced dorsiflexion during late stance; smaller plantarflexion push-off reduces propulsion.

• Foot strike: reduced heel strike with diminished ankle dorsiflexion at terminal stance; overall swing-phase clearance can be compromised.

• Upper body posture: less shoulder flexion, often a more extended posture; weight distribution tends to be placed more on the heel during ground contact (posteriorly biased CoM) which may be a protective strategy in those with fall risk histories.

• Older adults without a history of falls often walk with patterns similar to younger adults; gait changes are more pronounced in those with a falls history.

gait variability and measurement in ageing

• Gait variability reflects the ability to adapt to environmental demands; some variability is normal for adapting to surface changes, obstacles, and tasks.

• In clinical vs. unstable environments, gait should be relatively consistent on flat, controlled surfaces; high variability in step-to-step measures can indicate instability or increased fall risk.

• Measurement approach (example from GateRite video):

  • Step length can be extracted as the distance between consecutive heel strikes of the same foot or opposite feet, across a walk trial.

  • Variability is quantified as the standard deviation (SD) of step length across steps:

  • Example: step length left/right and SD values are generated, and higher SD indicates greater variability.

• Research findings: higher gait variability in older adults correlates with increased past falls or higher fall risk; in some data, impairment in variability is used to identify individuals at risk.

• A reference point: a normative database is available for comparison; deviations beyond the database suggest atypical gait patterns.

• Practical note: even with imaging or clinical tests, variability is a useful indicator of fall risk when walking in real-world environments.

• Example walkthrough (from a PhD study): a pressure-sensitive walkway captured multiple steps of an amputee, illustrating how to compute step length and its variability from raw footprints; the narrative emphasizes practical measurement of variability and its association with past falls.

• Takeaway: increased gait variability is not inherently bad, but abnormally high variability, especially in safe environments, signals potential instability and falls risk; variability can be used to guide interventions.

muscle activation and EMG changes with ageing

• In older adults, there is evidence of muscle over-activation and altered synergy patterns during gait, possibly due to changes in somatosensory feedback or guarded postures.

• Muscles with notable changes (highlighted in red in the lecture) include:

  • Tibialis anterior (often reported as over-activation during specific gait phases)

  • Biceps femoris (short head or long head depending on phase)

  • Rectus femoris

  • Peroneus longus

  • Gastrocnemius (gastroc) with over-activation around heel strike

• Functional consequences:

  • Reduced push-off power from plantar flexors (i.e., weaker or less effective toe-off during late stance).

  • Reduced quadriceps activation during late stance/early swing, affecting leg advancement.

• The overall pattern reflects a shift in when and how muscles fire during the gait cycle, contributing to a stiffer, guarded gait in older adults.

altered neuromuscular control with ageing

• This altered neuromuscular control can be linked to reduced somatosensory feedback and the need to protect the body from instability.

• Falls and muscle coordination:

  • A critical component of fall prevention is the ability to activate the correct muscle sequences in the right order (e.g., hip flexors for swing, ankle plantar flexors for stance) to recover from trips.

  • The magnitude and rate of force development (torque) are slower in older adults, not just the sheer strength of the muscle. Torque generation is a product of moment arm and force:

  • tau = r x F

  • Slower torque development reduces the speed and effectiveness of protective responses.

• Perturbation training as a preventive strategy:

  • Training that includes perturbations (e.g., controlled nudges, treadmill perturbations, or harness-supported environments) helps people learn to recruit the key muscles rapidly and efficiently to prevent a fall.

  • Practically, perturbations mimic trips and force individuals to adapt to maintain balance.

• Slip response considerations:

  • Slips require rapid, well-timed engagement of ankle and knee strategies to prevent a fall; with aging, the protective response can be less efficient, and older adults may increase co-activation around the ankle and knee and adopt shorter steps on slippery surfaces to reduce risk.

falls in ageing

• Fall aetiology in older adults is multifactorial: trips, slips, environmental hazards, and systemic factors.

• Trip-related falls account for ~35%-47% of falls in older adults.

• Slip-related falls account for roughly 27%-32% of falls.

• Sex differences: data suggest females may have a higher fall risk, potentially about four times greater in some datasets; potential contributing factors include hormonal changes, body composition, and muscle properties.

• Core fall-prevention targets include improving rapid, coordinated muscle responses (hip flexors for swing, ankle plantar flexors for push-off) and enhancing protective reflexes through targeted training (e.g., perturbation training).

• Key concepts in fall recovery:

  • It is not just strength but the timing and magnitude of torque generation that matter (i.e., how quickly muscles can generate the necessary forces).

  • The swing leg hip flexors and stance leg ankle plantar flexors are particularly critical in preventing a fall after a trip.

  • Older adults typically show slower torque generation and slower force development, which reduces their protective response speed.

• Perturbation training options in practice:

  • Therapist-assisted perturbations in a controlled setting (e.g., harness systems that prevent actual falls) or altered ground perturbations on specialized treadmills.

  • The goal is to train efficient, rapid recruitment of the hip flexors and plantar flexors to counter perturbations.

trips vs slips

• Trips: Require timely activation of hip flexors (swing leg) and ankle plantar flexors (stance leg) to clear the foot and re-establish stable gait.

  • The quality of the response depends on the magnitude and rate of muscle torque development; older adults show slower torque generation.

• Slips: Involve recovery of the foot after the sudden loss of friction; a slip can lead to a subsequent trip if the leg is swinging forward.

  • Protective responses often include co-activation around the ankle and knee and adopting shorter steps to stabilize the base of support.

• Training implications: Interventions should focus on rapid, coordinated muscle recruitment and not just isolated strengthening.

  • Perturbation-based training can help adults learn to respond more effectively to trips and slips in everyday environments.

sensory factors influencing gait with ageing

• Somatosensorial (somatosensory input): Peripheral neuropathy reduces tactile feedback and proprioception, often accelerated by diabetes. Consequences include slower fast-walking speeds and higher fall risk: Vision and proprioception interplay in foot placement and ground contact; neuropathy can lead to flatter foot contact and altered foot mechanics.

  • Example image summary: peripheral neuropathy can show reduced plantar flexion push-off and dorsiflexion at heel strike, with a flatter foot contact and altered foot orientation during gait.

• Vision: Visual changes with aging affect the ability to detect obstacles and plan reactive steps; nighttime walking increases risk due to reduced lighting.

  • Those with compromised vision or poor tug test performance tend to walk more slowly and with heightened guarding behaviour.

• Vestibular function: Vestibular decline with age is linked to reduced gait speed and stability; vestibular cues are used to maintain balance during movement.

cognitive changes and gait

• Normal aging is associated with some cognitive change, and gait becomes more automated but attentional demands can rise with age, especially for safety.

• Dual-tasking impact on gait: Walking while performing a cognitive task (e.g., serial subtractions by seven) increases attentional demands and reduces gait stability.

  • Example task: serial subtractions by seven while walking is used to probe cognitive-motor resource allocation and to assess dual-task costs.

  • A practical metric: Dual-task cost (DTC) can be defined as:

  • DTC = Psingle – Pdual / Psingle   x 100%,

  • where P denotes performance (e.g., speed, accuracy) under single-task vs. dual-task conditions.

• Training implications include integrating walking practice with cognitive tasks to promote automatization and enhance safe dual-task performance.

other factors affecting gait in older adults

• Pain and musculoskeletal discomfort can alter walking patterns (guarded or protective strategies).

• Cardiopulmonary limitations can limit endurance and walking speed.

• Fear of falling, anxiety, and previous falls influence gait and caution levels.

• Medications may affect balance, alertness, and coordination.

• Footwear quality and footwear choices (e.g., slippers) influence gait safety and stability.

• Psychiatric factors (e.g., depression) can also affect motivation, energy, and gait patterns.

environment and mobility

• Stairs: Falls on stairs account for about 10% of fall-related deaths, which is notable given the relatively small proportion of daily stair use.

  • Descent is more hazardous than ascent, by a factor of ~4x, due to greater demands on ankle/ knee/hip control and reduced sight lines.

  • Typical age-related changes on stairs include reduced cadence, longer foot clearance, and more posterior foot placement; older adults often use a wide base of support and two-handed handrail, with cautious foot placement and sometimes external rotation of the stepping foot.

• Backwards walking: Older adults typically show reduced stride length when walking backwards and often increase cadence to go faster without increasing step length.

  • There is reduced hip flexion, knee flexion, and ankle flexion when stepping backwards, and reduced hip extension in backward walking.

  • These patterns reflect decreased confidence and altered motor control in the reverse gait task.

practical implications and assessment and intervention

• When evaluating gait in older adults, consider multiple interacting mechanisms: vision, somatosensorial, vestibular function, cognition, pain, fatigue, medications, footwear, and psychological factors.

• Distinguish primary aging changes from secondary, potentially modifiable factors (nutrition, exercise, stress management, diabetes control, vascular health) to tailor interventions.

• Interventions should address not only strength but also the speed and timing of torque development (i.e., the ability to recruit key muscles quickly and in the correct order).

• Incorporate perturbation-based and task-specific training to improve reactive balance, hip flexor and ankle plantar flexor recruitment, and gait adaptability in real-world environments.

• In daily practice, encourage safe exploration of real-world tasks (stairs, curb negotiation, stairs descent, walking on uneven surfaces) with appropriate safety supports (harnesses, rails) during rehabilitation to build confidence and reduce fall risk.

summary and takeaways

• Older adults commonly show slower gait, shorter step length, reduced cadence, and longer double-support time; these changes are related and can be more pronounced in females due to hormonal/muscle-property differences.

• Kinematic changes include reduced flexion at the hip/knee/ankle, decreased dorsiflexion during late stance, and reduced vertical/lateral head movement, contributing to lower foot clearance and increased tripping risk.

• Muscle activation patterns in aging show over-activation in several muscles (e.g., gastrocnemius, peroneus longus, tibialis anterior, rectus femoris, biceps femoris) with reduced push-off power and altered timing; torque development is slower rather than just weaker muscle strength.

• Falls are a major issue; trips (~ 35%-47%) and slips (~ 27%-32%) are common causes, with sex differences and context-specific risks. Prevention focuses on rapid muscle recruitment and perturbation-based training.

• Sensory (somatosensory, vision, vestibular) and cognitive changes contribute to gait alterations; dual-task declines reveal limited cognitive resources for safe walking, emphasising the importance of rehabilitation that integrates motor with cognitive demands.

• Environment-specific mobility (stairs, backward walking) presents unique challenges; descent on stairs is particularly hazardous and may require specific training and safety strategies.

• Clinicians should assess a broad range of underlying mechanisms and tailor interventions to improve safety, independence, and quality of life for older adults.

functional reach test (FRT) (outcome measure)

The Functional Reach Test (FRT) is a single item test that assesses a person's stability by measuring the maximum distance one can reach forward while standing in a fixed position.

If your patient is unable to stand, the FRT has been modified to be assessed in sitting.

·      Sitting with the unaffected side near the wall and leaning forward.

·      Sitting with the back to the wall and leaning right.

Sitting with the back to the wall leaning left.

• tests anticipatory and dynamic posutural control

brief BESTest

seperate sheet instrument

• tests anticipatory, dynamic, reactive postural control

stork balance test

tests anticipatory and steady state

• one leg off ground but resting on the side of the other leg

star excursion balance test (SEBT)

You are assessing dynamic postural control, specifically:

• Anticipatory postural adjustments (APAs): preparing the body for the reach.

• Reactive postural adjustments (RPAs): maintaining balance when the centre of mass shifts.

• Single-leg stance stability.

• Proprioception and neuromuscular control of the hip, knee, and ankle.

• Control of trunk and pelvic alignment during movement.

the ability to maintain balance during reaching tasks.