Effects of age and mild cognitive impairment on postural control during lifting a load.

Young adults generated significantly greater anticipatory postural adjustments (APAs) in muscle activity and exhibited larger anticipatory COP responses than both older groups during the heavy-to-light load transition.

• 12 young adults (YAH), 13 healthy older adults (OAH), and 15 older adults with MCI (OAMCI) participated in the study.
• Participants performed 35 trials of bimanual lifting of light and heavy loads in standing position.
• The difference in APAs was statistically significant at p < .05.
• Surface electromyography was collected bilaterally from trunk and lower limb muscles, with EMG integrals calculated during APA and CPA phases.
• Center of pressure (COP) displacements were derived from force platform data.

Young adults produced larger compensatory postural adjustments (CPAs) in COP responses across load transitions compared to older groups.

• COP displacements were measured across both light-to-heavy and heavy-to-light load transitions.
• Both older groups (OAH and OAMCI) showed reduced compensatory COP responses relative to YAH.
• This finding is consistent with aging being associated with reduced efficiency of APA generation and greater reliance on CPAs.
• The pattern was observed across transitions (both light-to-heavy and heavy-to-light conditions).

Older adults with MCI showed reduced tibialis anterior (TA) activation during the light-to-heavy load transition compared to other groups.

• The OAMCI group comprised 15 older adults with mild cognitive impairment.
• TA activation reduction was specific to the light-to-heavy transition condition.
• This finding suggests impaired anticipatory muscle recruitment in individuals with MCI when preparing for a heavier load.
• The TA is a lower limb muscle involved in postural stabilization during lifting tasks.

Older adults with MCI demonstrated exaggerated APAs in posterior and lateral muscles during the heavy-to-light transition compared with healthy older adults.

• The exaggerated APA response in OAMCI was statistically significant compared to OAH (p < .05).
• The exaggeration was specific to posterior and lateral muscles during the heavy-to-light transition.
• This pattern was described as 'exaggerated yet less targeted,' suggesting impaired strategy selection.
• The contrast between reduced TA activation in one condition and exaggerated posterior/lateral muscle activity in another indicates differential and less coordinated postural control in MCI.

Change-point analysis indicated faster adaptation to load changes in young adults than in both older groups.

• Change-point analysis was used to assess the rate of adaptation to load changes across the 35 lifting trials.
• Both OAH and OAMCI showed slower adjustment compared to YAH.
• This finding reflects reduced adaptive capacity in aging regardless of cognitive status.
• The slower adaptation in older groups is consistent with reduced anticipatory postural efficiency associated with aging.

Aging is associated with reduced efficiency of APA generation and greater reliance on compensatory postural adjustments (CPAs).

• This relationship between aging and postural control strategy forms a foundational premise of the study.
• The role of Mild Cognitive Impairment in postural control during lifting was described as 'unclear' prior to this study.
• Lifting everyday objects was characterized as destabilizing the body and requiring both anticipatory and compensatory postural adjustments to maintain balance.
• The study used a bimanual lifting task to investigate these postural control mechanisms.