Sit-to-Stand Muscular Activity for Different Seat Backrest Inclination Levels and Execution Speeds

Area of Science:

• Biomechanics
• Human Movement Analysis
• Musculoskeletal Physiology

Background:

• The sit-to-stand (STS) movement is fundamental for daily activities.
• Understanding the complex muscle activation patterns during STS is crucial for rehabilitation and ergonomics.
• Variations in STS execution, such as backrest inclination and speed, are not fully characterized.

Purpose of the Study:

• To investigate the whole-body muscular activity during the postural and focal phases of the sit-to-stand transfer.
• To analyze how backrest inclination affects muscle engagement during STS.
• To examine the influence of execution speed on muscle activity during the sit-to-stand task.

Main Methods:

• Surface electromyography (EMG) was used to record the activity of fifteen trunk and lower limb muscles.
• Ten participants performed sit-to-stand transfers under varying backrest inclinations and execution speeds.
• Data analysis focused on comparing muscle activity between different phases and conditions.

Main Results:

• Backrest inclination primarily modified the postural phase of the STS transfer.
• Reclining the backrest prolonged the postural phase and increased activity in specific trunk and hamstring muscles.
• Increased execution speed predominantly affected the postural phase, shortening its duration and increasing overall muscle activation.

Conclusions:

• Backrest inclination and execution speed significantly modulate muscle activity during the sit-to-stand transfer, particularly in the initial postural phase.
• These findings provide insights into the biomechanics of STS and can inform interventions for individuals with mobility impairments.
• Optimizing STS parameters based on individual needs may enhance movement efficiency and reduce injury risk.