Head and Neck Posture, Deep Neck Flexors Performance and Tongue Force in Healthy Young and Older Adults.

The objective of this study was to evaluate the head and neck posture, the deep neck flexors (DNF) performance, and tongue force in a group of healthy young and older adults. The correlation between head and neck posture and the DNF performance was also evaluated. 

Healthy young and older adults participated. The natural sagittal head and neck posture in seating position was evaluated visually using a plumb line, and with photogrammetry by measuring the craniovertebral angle in a picture taken from each subject. The maximum tongue force was measured with the Iowa Oral Performance Instrument (IOPI) for 3 seconds. The subjects performed the craniocervical flexion test (CCFT) to evaluate the activation and resistance of the DNF muscles using an air-filled pressure sensor. Mixed Anova was used to test the relationship between posture classification and CVA measures while accounting for groups. The correlation between the performance of the CCFT and CVA was calculated using Pearson correlation. 

A total of 36 subjects consisted of a younger group of 19 subjects (26.37±3.35; 14 females) and an older group of 17 subjects (66.18±6.27; 12 females) participated. Nine subjects were classified as having FHP in the younger group (47.4%) and 13 were classified with FHP in the older group (76.5%). Lower CVA was found for subjects with FHP (43.1°) compared to subjects with upright posture (52.5°). A significant difference in CCFT pressure score (DNF activation) between groups was found (p=0.034). A significant and moderate positive correlation (r=0.36, p=0.036) between CCFT activation pressure score and CVA was found. Tongue force was showed to be significantly different (p=0.008) between groups (older group: mean 50.18±8.43, younger group: mean 59.32±10.67). 

More head and neck posture alteration (FHP), less tongue force, and less activation of the DNF muscles (weakness) was found in healthy older adults compared to the healthy younger adults. A more upright head and neck posture was correlated with a better performance of the CCFT.  

This is the first study evaluating the DNF muscles and their importance on the function of swallow related measures including tongue force. This study may contribute to improving the rehabilitation of patients with oral dysfunction. Postural rehabilitation (including DNF strengthening) may be recommended which may increase collaborations between physical therapists and speech language pathologists. Future studies should include subjects with swallowing related dysfunction.