The relationship between latent trigger point and muscle strength in healthy subjects: A double-blind study

Background: Trigger points on the palpable taut bands of the muscles are promoted as an important cause of musculoskeletal pain. Our hypothesis was latent trigger points (LTrPs) could decrease muscle strength also in healthy people. Objectives: The aim of our study was to investigate the relationship between LTrPs and muscle strength in a group of healthy adults. Methods: In total fifty healthy adults (20 women and 30 men) were included in the study. Trigger point examination for upper and middle trapezius, supraspinatus, serratus anterior and rhomboid major and minor were done bilaterally according to four criteria. Subjects who have at least two trigger points in dominant side were assigned to Group 1 (28 subjects), subjects who don't have any trigger points were assigned to Group 2 (23 subjects). Muscle strength for flexion and scaption was assessed with a Hand-Held Dynamometer (HHD) as break test on both sides. Both the subjects and the examiners were blind. For statistical analysis, independent sample t test was used to compare the differences between two groups. Results: No significant differences were found in muscle strength between dominant and non-dominant sides in both groups (p > 0.05). Significant difference was observed in both sides when comparison of muscle strength between Group 1 and 2, muscle strength was lower in subjects who had trigger points (p < 0.05). Conclusions: This study indicated that although there is not significant difference between dominant and non-dominant side, muscle strength is lower significantly in both sides in subjects who have trigger points in comparison with healthy subjects. Our results underline the importance of palpation of LTrPs in scapular and shoulder muscles in healthy subjects as they may contribute to the muscle strength. Further research is neded to facilitate a better understanding of the mechanism of LTrPs and to test the relationship with muscle strength.