Postural factors contributing to reaching speed and accuracy

Area of Science:

• Biomechanics
• Occupational Health
• Ergonomics

Background:

• Faulty postures during occupational reaching tasks can lead to inefficient movement patterns and potential injuries.
• Understanding the interplay between posture and muscle activation is crucial for identifying injury risks in workers.

Purpose of the Study:

• To investigate the predictive relationships between postural factors, muscle activation, and forward reaching performance and accuracy.
• To determine how specific postural variables and muscle co-activation influence movement outcomes in occupational reaching tasks.

Main Methods:

• Analyzed forward shoulder posture (FSP), pectoral length, upper (UT), middle (MT), and lower trapezius (LT), and pectoralis major (PM) muscle activation in 56 individuals.
• Assessed UT:PM, MT:PM, and LT:PM co-activation during forward reaching tasks.
• Utilized sequential linear regression to analyze reaching variance.

Main Results:

• In females, FSP, UT activation, and UT:PM co-activation predicted 36% of reaction time (RT) variance; MT:PM co-activation predicted 14% of endpoint accuracy variance.
• In males, MT:PM co-activation predicted 17% of movement time (MvT) variance; FSP, MT:PM co-activation, and MT predicted 23% of accuracy variance.
• Increased muscle co-activation predicted movement performance, with differing outcome variables (MvT vs. RT) between sexes.

Conclusions:

• Muscle co-activation, forward shoulder posture (FSP), and posterior shoulder muscle activation significantly influence reaching performance variance.
• Practitioners should consider evaluating these muscle activation and postural factors in occupational reaching assessments.
• Findings suggest sex-specific differences in how postural and muscle activation factors predict reaching performance.