The effect of finger joint hypomobility on precision grip force

Effect of extension of the ulnar fingers on force control and muscle activity of the hand during a precision pinch

Some individuals extend the three ulnar fingers when performing a precision pinch. The aim of the present study was to investigate the mechanisms and effect of the extension of the ulnar fingers during a pinch. When performing a pulp pinch task with the ulnar fingers in two positions (extension and flexion), 27 participants maintained 5% of their maximum force. The mean pinch force, force variability and time taken to reach the targeted force (reaching time) were calculated. Muscle activity was simultaneously measured, using surface electromyography, for nine muscles: the flexor pollicis brevis; abductor pollicis brevis; flexor pollicis longus; first lumbrical; first dorsal interosseous; flexor digitorum superficialis of the index finger; extensor indicis; and extensor digitorum of the index and ring fingers. No significant differences in the mean pinch force or force variability were found. However, the reaching time was significantly shorter (approximately 20% reduction) in the extension position and the activities in the flexor pollicis brevis, first lumbrical, extensor indicis and extensor digitorum of the ring finger were significantly higher. These findings suggest that extending the ulnar fingers during pinching enhances the activity of key muscles involved in the movement and allows for more rapid force exertion.

Immediate Effects of a Single Spinal Manipulation on Lower-Limb Strength in Healthy Individuals: A Critically Appraised Topic

Clinical Scenario: Many people with lower quarter musculoskeletal dysfunction present with muscle weakness. Strength training hypertrophies muscle and increases strength, but often requires periods over 6 weeks, which can exceed the episode of care. Weakness can persist despite muscle hypertrophy, particularly in the early stages of joint pathology or in the presence of limb or spinal joint hypomobility, which may inhibit muscle activation. Emerging evidence suggests spinal manipulation can increase short-term strength. Screening for specific muscle weakness that could benefit from manipulation to particular spinal segments could facilitate efficient clinical intervention. Although the neuromuscular mechanisms through which manipulation can increase strength remains a topic of investigation, immediate gains can benefit patients by jump-starting an exercise program to train new muscle function gained and enhancing the motivation to continue strengthening. Evidence from randomized controlled trials would provide support for using manipulation to increase muscle strength, while studying healthy people would eliminate confounding factors, such as pain and pathology. Clinical Question: Does randomized controlled trial-level evidence support the concept that a single lumbar spine manipulation session can increase lower-limb strength in healthy individuals? Summary of Key Findings: Level 1b evidence of moderate quality from 3 randomized controlled trials showed immediate small to large effect size muscle strength increases immediately after lumbar spine manipulation. Clinical Bottom Line: Lumbar spine manipulation can result in immediate lower-limb isometric strength increases. While healthy people with normal muscle strength may improve minimally, joint manipulation for people with knee and hip weakness who are otherwise healthy can result in large effect size strength gains. Strength of Recommendation: Moderate quality level 1b evidence from randomized controlled trials with small samples support the use of spinal manipulation to immediately increase lower-limb strength. Additional studies investigating impact on strength and function immediately in people with musculoskeletal pathology are warranted.

Effects of cervical manipulation on pain, grip force control, and upper extremity muscle activity: a randomized controlled trial

Objectives

Individuals with neck pain experience disrupted grip force control when performing manipulative tasks. Manipulative physical therapy might decrease pain and change the activity of surrounding muscles; however, its effect on upper limb motor control remains undetermined. This study aims to analyze the effects of cervical manipulation on pressure pain threshold (PPT), upper extremity muscle activity along with grip force control in individuals with neck pain.

Methods

Thirty subjects with neck pain were instructed to grasp and lift an object before and after cervical (n = 15) or sham (n = 15) manipulation. The patients' PPT, electromyographic (EMG) activity of the upper extremity/scapular muscles, and grip force control were analyzed before and after one session of manipulation.

Results

No significant differences were found in the grip force control, PPT and EMG activity variables between groups.

Discussion

These results suggest that a single session of cervical manipulation may not modify upper limb motor control, more specifically grip force control and EMG activity, in patients with cervical pain. Future studies should investigate potential changes in grip force control in patients with different features of neck pain and/or by applying long-term treatment.

Level of Evidence

1b.