Handgrip Strength Exercises Modulate Shoulder Pain, Function, and Strength of Rotator Cuff Muscles of Patients with Primary Subacromial Impingement Syndrome

Abstract

Background: Impingement syndrome was shown to be associated with shoulder pain in 44-70% of patients worldwide. It usually occurs due to imbalance and insufficient activation of the rotator cuff (RC) muscles.

Aim: This study explores the relative effects of handgrip-strengthening exercises on shoulder function, pain, strength, and active range of motion as part of the treatment program for the patients with primary subacromial impingement syndrome.

Materials and methods: A total of 58 patients aged 18-50 years with primary subacromial impingement syndrome were randomly enrolled to participate in this single-blind randomized clinical trial. Out of them, only forty patients have eligibly matched the inclusion criteria and randomly assigned to one of two groups to undergo a standardized therapeutic program consisting of two sessions a week for 8 weeks. The control group prescribed ultrasound therapy, ice, and stretching exercises, while the experimental group followed the same program with the addition of handgrip-strengthening exercises (HGSE). Both patients of conventional therapy (control) and handgrip-strengthening exercises (experimental group) were advised to adhere also to stretching and HGSE exercises once a day at home for eight weeks. The outcomes were the shoulder function, pain intensity, muscle strength, and active range of motion of the shoulder joint.

Results: Patients treated with conventional interventions plus handgrip-strengthening exercises showed the significant improvement over time in shoulder pain and function, strength of rotator cuff muscles, and pain-free range of motion forward flexion, abduction, and external and internal rotation through eight weeks in the experimental group compared to control patient group treated with conventional interventions. In addition, patients of both control and experimental groups showed no significant difference in the adherence to respective home-based stretching and HGSE exercises once a day at home for eight weeks.

Conclusions: Adding handgrip-strengthening exercises to conventional intervention increases the efficacy of treatment for patients with primary subacromial impingement syndrome in terms of shoulder function, pain, muscle strength, and active range of motion.

Figure 1

Flowchart of participants through each stage of the study.

Figure 2

Handgrip-strengthening exercises using an adjustable heavy-grip handgripper at different sets (30°, 60°, and 90°); (a) 1^st and 2^nd weeks at 30°, (b) 3^rd and 4^th weeks at 60°, (c) 5^th and 6^th weeks at 90°, and (d) 7^th and 8^th weeks at 90°.

Figure 3

Strength of rotator cuff muscle measured by a hand-held dynamometer (HHD). (a) Internal rotation; (b) external rotation.

Figure 4

Measurement of ROM of shoulder joint using a smartphone inclinometer. (a) Internal rotation, (b) external rotation, (c) abduction, and (d) forward flexion.

Figure 5

Difference in adherence to physical therapy sessions, home program, and adverse effect of handgrip-strengthening exercises. The data expressed as %. p value is significant at the <0.05 level (2-tailed).

Figure 6

Improvement in shoulder function, muscle strengths, pain, and pain-free active range of motion (AROM) in patients with primary SAIS treated with handgrip-strengthening exercise (experimental group) compared to patients treated with conventional physical therapy interventions (control patients group). Repeated measure ANOVA adjusted for age and gender showed significant improvements in pain (a), shoulder function (DASH score) (b), muscle strength IR (c), and ER (d) for with primary SAIS patients treated with handgrip-strengthening exercise at respective time intervals (4 weeks and 8 weeks), respectively, compared to patients treated with conventional physical therapy interventions (controls). The improvements in the syndromes of primary SAIS are time trend.

Figure 7

Changes in pain-free active range of motion (AROM) in patients with primary SAIS treated with handgrip-strengthening exercise (experimental group) compared to patients treated with conventional physical therapy interventions (control patients group). Active range of motions (AROM) of forward flexion and abduction of the rotator cuff (RC) muscles were significantly improved following handgrip-strengthening exercise interventions for 8 weeks compared to those treated with conventional physical therapy interventions (a, b). However, SAIS patients of both treating interventions (experiment and control groups) showed no significant difference in active range of motions (AROM) for both internal and external rotations of the rotator cuff (RC) muscles at respective treating time intervals (4 weeks and 8 weeks) (c, d).

Figure 8

Effectiveness of the treatment duration on the efficiency of both conventional and handgrip-strengthening exercise interventions to improve the primary SAIS syndromes. The results showed all come out clinical measures, VAS, DASH, muscle strength, and pain-free active ROM measures were significantly improved over scheduled time of treatment. The clinically improved measures are significantly correlated at time intervals; 4 weeks (a), 8 weeks (b), and 4–8 weeks (c) compared to baseline data which concluded that treatment of primary SAIS syndromes with conventional interventions either alone or with handgrip-strengthening exercise interventions during 8 weeks is time-dependent.