Isometric Neck Strength Research Articles

Isometric Strength of the Cervical Flexor, Extensor, and Rotator Muscles in 220 Healthy Females Aged 20 to 59 Years

Cross-sectional descriptive study. To determine the maximal isometric strength of the flexor, extensor, and rotator muscles of the cervical spine in healthy females of working age to document reference values for diagnostic and rehabilitation purposes. Reference values for the isometric strength of the cervical muscles have often been based on small samples. To date, reference values for rotator muscles of the cervical spine have not been published. The group consisted of 220 volunteer healthy females in 4 age groups (20-29 years, n = 57; 30-39 years, n = 51; 40-49 years, n = 51; 50-59 years, n = 61) from Jyadskyla, Finland. Isometric cervical muscle strength in flexion, extension, and rotation was evaluated with a specially designed measurement system. Across all age groups, mean (+/-SD) maximal isometric neck strength was 73.8 +/- 20.0 N in flexion and 190.8 +/- 31.3 N in extension. Mean (+/-SD) rotation strength was 8.1 +/- 2.3 Nm to the right and 7.9 +/- 2.3 Nm to the left. Absolute strength values did not differ among the age groups. A weak but significant correlation between body mass and neck flexion (r = 0.31, P<.01) and extension (r = 0.25, P<.01) strength was found. Intratester reliability varied from 0.87 to 0.96. Women aged 20 to 59 years appear to have similar absolute isometric neck muscle strength levels. Thus these values can be used as reference for the working-age female population.

Effects of Neck Muscle Training in Women With Chronic Neck Pain: One-Year Follow-up Study

Exercises are commonly recommended for chronic neck pain, but evidence-based guidelines do not explain what types of exercise. The aim of this randomized study was to evaluate the rate of change in neck strength following high- and low-intensity neck muscle training and their effects on pain and disability. One hundred eighty women with chronic neck pain were randomized into a high-intensity strength training group (STG), local muscle endurance training group (ETG), or control group (CG). The neck training consisted of isometric exercises in the STG and dynamic exercises in the ETG. Both groups performed dynamic exercises for the upper extremities. Strength tests, neck pain, and disability indices were evaluated at the baseline, at the follow-ups after 2 and 6 months in the training groups, and after 12 months in all groups. In both groups the greatest gains in neck strength, as well as decrease in neck pain and disability, were achieved during the first 2 months. However, the improvements continued up to 12 months. The STG achieved the greatest strength gains at all follow-ups. The CG showed only minor changes, and significant differences were found in favor of the training groups in all measures. The change in neck pain and disability indices correlated with the isometric neck strength (r = -0.22 [-0.36 to - 0.08] to -0.36 [-0.49 to -0.23]). Neck and shoulder muscle training was shown to be an effective therapy for chronic neck pain, resulting in early improvement in both the strength tests and subjective measures. The results can be maintained and even improved with long-term training.

Effects of Twelve-Month Strength Training Subsequent to Twelve-Month Stretching Exercise in Treatment of Chronic Neck Pain

Previously, in a randomized study, we showed that women with chronic neck pain were able to perform intensive training for neck and shoulder muscles and that the increase in strength was accompanied by a reduction in pain and disability. The changes were significantly greater in the training groups compared with controls. The aim of the present study was to evaluate whether the controls would achieve similar results. Thus, 59 women in the control group initiated high-intensity strength training. Maximal isometric neck strength increased by 44% in both flexion and rotation and 27% in extension at the 2-year follow-up. Statistically and also clinically significant decreases in neck pain and disability indices occurred. Stretching and aerobic exercising during the first follow-up year produced only minor changes in both subjective and functional measures. Adding progressive strength training for the second year led to a significant improvement in neck strength and also to a considerable decrease in the pain and disability scores. Thus, to achieve effective rehabilitation in cases of chronic neck pain, a combination of strength training and stretching exercises are recommended.

Decreased Muscle Strength and Mobility of the Neck in Patients With Rheumatoid Arthritis and Atlantoaxial Disorders

Häkkinen A, Neva MH, Kauppi M, Hannonen P, Ylinen J, Mäkinen H, Jäppinen I, Sokka T. Decreased muscle strength and mobility of the neck in patients with rheumatoid arthritis and atlantoaxial disorders. Objective To compare neck muscle strength and mobility of the cervical spine in rheumatoid arthritis (RA) patients with and without atlantoaxial (AA) disorders (anterior atlantoaxial subluxation [AAS], AA impaction). Design Clinical cross-sectional study. Setting Outpatient rheumatology and rehabilitation clinics in a Finnish hospital. Participants Patients with RA (N=124; mean age ± standard deviation, 62±y) on a waiting list for orthopedic surgery. Thirty (24%) patients presented with AA disorders (16 with anterior AAS, 8 with AA impaction, 6 with a combination of anterior AAS and AA impaction). Interventions Not applicable. Main Outcome Measures Neck function was measured by isometric neck strength and mobility tests, neck pain by a visual analog scale, erosion of the hands and feet by radiography, and the patients’ function by the Health Assessment Questionnaire (HAQ). Results Maximal neck muscle strength against flexion, extension, and rotation was lower in patients with AA disorders compared with the other patients in both women ( P=.012) and men ( P=.017). Mobility was lowest in the AA impaction group in all measured directions ( P<.001). Peripheral erosive disease was more frequent in the group with AA disorders. They also had longer disease duration and were more disabled (HAQ) than the other patients. Conclusions Neck muscle strength is significantly decreased in patients with AA disorders. Mobility of the cervical spine is most limited in patients with AA impaction, but can be normal in cases with solitary anterior AAS.

Decreased neck muscle strength is highly associated with pain in cervical dystonia patients treated with botulinum toxin injections

Häkkinen A, Ylinen J, Rinta-Keturi M, Talvitie U, Kautiainen H, Rissanen A. Decreased neck muscle strength is highly associated with pain in cervical dystonia patients treated with botulinum toxin injections. Arch Phys Med Rehabil 2004;85:1684–8. Objectives To compare the isometric neck muscle strength of cervical dystonia patients treated with botulinum toxin injections with that of healthy control subjects and to evaluate the association between neck strength, neck pain, and disability in these patients. Design Clinical cross-sectional study. Setting Outpatient rehabilitation and neurology clinics in a Finnish hospital. Participants Twenty-three patients with cervical dystonia with botulinum toxin—treated neck muscles and 23 healthy control subjects. Interventions Not applicable. Main outcome measures Isometric neck strength was measured by a special neck strength measurement system. Disability was measured by the Neck Disability Index, and pain and symptoms of cervical dystonia by a visual analog scale. Results Isometric neck strength in all directions measured was significantly lower (25%–44%) in the cervical dystonia patients than in the healthy controls. Neck pain levels reported during the strength tests ( r range, −.36 to −.70) and neck pain experienced during the preceding week ( r range, −.52 to −.63) were inversely associated with isometric strength results. The difference between sides in rotation strength was 35% in the patient group ( P<.001), whereas no significant difference between sides was found in the healthy controls. Fifty-one percent of the patients reported moderate or severe disability. Pain, stiffness, and incorrect position of the head were the most prominent symptoms. Conclusions Cervical dystonia patients with botulinum toxin—treated neck muscles showed significantly lower maximal neck strength than healthy controls. The patients also had a statistically significant difference between sides in neck rotation strength. Thus, strength measures may be useful to detect disturbance in the function of the neck muscles.

Decreased isometric neck strength in women with chronic neck pain and the repeatability of neck strength measurements

Ylinen J, Salo P, Nykänen M, Kautiainen H, Häkkinen A. Decreased isometric neck strength in women with chronic neck pain and the repeatibility of neck strength measurements. Arch Phys Med Rehabil 2004;85:1303–8. Objectives To evaluate neck flexion, extension, and, especially, rotation strength in women with chronic neck pain compared with healthy controls and to evaluate the repeatability of peak isometric neck strength measurements in patients with neck pain. Design Cross-sectional. Settings Rehabilitation center and physical and rehabilitation medicine department at a Finnish hospital. Participants Twenty-one women with chronic neck pain and healthy controls matched for sex, age, anthropometric measures, and occupation. Interventions Not applicable. Main outcome measures Peak isometric strength of the cervical muscles was tested in rotation, flexion, and extension. Results Significantly lower flexion (29%), extension (29%), and rotation forces (23%) were produced by the chronic neck pain group compared with controls. When the repeated test results were compared pairwise against their mean, considerable variation was observed in the measures on the individual level. Intratester repeatability of the neck muscle strength measurements was good in all the 4 directions tested in the chronic neck pain group (intraclass correlation coefficient range, .74–.94). The coefficient of repeatability was 15N, both in flexion and extension, and 1.8Nm in rotation. On the group level, improvement up to 10% due to repeated testing was observed. Conclusions The group with neck pain had lower neck muscle strength in all the directions tested than the control group. This factor should be considered when planning rehabilitation programs. Strength tests may be useful in monitoring training progress in clinical settings, but training programs should be planned so that the improvement in results is well above biologic variation, measurement error, and learning effect because of repeated testing.

Association of neck pain, disability and neck pain during maximal effort with neck muscle strength and range of movement in women with chronic non-specific neck pain

Several studies have reported lower neck muscle strength in patients with chronic neck pain compared to healthy controls. The aim of the present study was to evaluate the association between the severity of neck pain and disability with neck strength and range of movement in women suffering from chronic neck pain. One hundred and seventy-nine female office workers with chronic neck pain were selected to the study. The outcome was assessed by the self-rating questionnaires on neck pain (visual analogue scale, Vernon's disability index, Neck pain and disability index) and by measures of the passive range of movement (ROM) and maximal isometric neck muscle strength. No statistically significant correlation was found between perceived neck pain and the disability indices and the maximal isometric neck strength and ROM measures. However, the pain values reported during the strength tests were inversely correlated with the results of strength tests ( r=−0.24 to −0.46), showing that pain was associated with decreased force production. About two-thirds of the patients felt pain during test efforts. Pain may prevent full effort during strength tests and hence the production of maximal force. Thus in patients with chronic neck pain the results do not always describe true maximal strength, but rather the patients' ability to bear strain, which may be considerably influenced by their painful condition. The results of the present study suggest that rehabilitation in cases of chronic neck pain should aim at raising tolerance to mechanical strain.

Both endurance training and strength training reduced disability and pain in chronic non-specific neck pain in women

(2003) JAMA 289, 2509. Ylinen J, Takala EP, Nykänen M, et al. . Active neck muscle training in the treatment of chronic neck pain in women: a randomized controlled trial....

Axial neck rotation strength in neutral and prerotated postures

Objective. To characterize isometric rotation strength in the neutral and in different prerotated positions of the neck. Design. This was a descriptive study involving maximal isometric strength measurements of the cervical musculature. Background. The literature contains only a few studies pertaining to strength levels of the neck rotator muscles in the neutral position. None of these studies have dealt in detail with maximal neck strength in selected prerotation positions. Method. Twenty healthy men volunteered as subjects. Maximal axial rotation strength of the neck muscles was measured in a neutral position and bilaterally at 30° and 60° rotation using the isometric neck strength measurement system. Isometric maximum voluntary contractions of the neck muscles in flexion and extension were also tested. Results. The highest strength values were not reached in the neutral position, but at the largest joint angles, while turning the head in the opposite direction from the prerotated position. Maximal strength increased with increasing angle, and at the 60° prerotation angle it was 44% higher towards the right and 27% higher towards the left compared to the values obtained in the neutral position. The smallest strength values were also produced at the largest prerotation angles, but in the same direction. Conclusions. The present results show a clear relationship between the prerotated position of the neck and maximal voluntary strength in rotation. Relevance The data suggest that neck strength is highly prerotation angle dependent. Neck strength should be measured at several prerotation positions in addition to the neutral position in order to obtain the true strength values throughout the entire range of motion. Maximal neck rotation strength between subjects is differentiated best at the greatest prerotation angles.

Effect of training in Greco-Roman wrestling on neck strength at the elite level.

Special training methods in wrestling have been assumed to improve the stability and tolerance of the neck. The aim of this study was to measure the neck strength levels reached in an extremely physically demanding sport. A neck strength measurement system was used to measure various parameters of maximal isometric neck strength in Finnish senior wrestlers competing at the international level. The results were compared with those achieved by junior wrestlers and a control group. The means (SD) of the maximal isometric neck strength for cervical rotation were 0.4 (0.1) Nm.kg(-1) for the senior wrestlers, 0.3 (0.1) Nm.kg(-1) for the junior wrestlers, and 0.2 (0.1) Nm.kg(-1) for the nonsportsmen. The respective results for cervical flexion were 4.4 (1.4), 3.8 (0.7), and 2.3 (0.8) Nm.kg(-1); for extension, 6.0 (1.1), 5.9 (0.7), and 4.0 (0.9) Nm.kg(-1). Neck strength in flexion seems to improve more than in extension as the result of wrestling. The greatest difference was found in rotation, which in the senior wrestlers was almost 3 times that in the nonsportsmen. There was great individual variation within all groups, and the results revealed weaknesses in all directions. Maximal neck strength measurements provide information useful in planning training programs to correct possible muscle deficiency and imbalance.

Intra- and inter-tester reliability and reference values for isometric neck strength.

Age- and sex-specific reference values for neck strength based on reliable measurements in the upright position are lacking. The aim of the present study was to determine intra- and inter-tester reliability and age- and sex-specific reference values for isometric neck strength in extension, flexion and lateral flexion in sitting position measured with the David Back Clinic 140 (DBC 140) equipment. The reliability of the DBC 140 equipment was investigated in 30 healthy volunteers and reference values were obtained from 101 healthy men and women. The reliability study showed that neck strength measured with the DBC 140 equipment has almost perfect intra- and inter-tester reliability (ICC values between 0.85 and 0.97). The mean value of the first in a series of three measurements was the highest for all three test leaders and for almost all directions. Results from the reference value study showed that gender is a much more important determinant of neck strength than age, body weight or body mass index (BMI). Neck strength in women was, on average, 55% of that in men, and when adjusted for body weight or BMI, the percentages were 70% and 59%, respectively. In all directions observed, neck strength decreased by approximately 20% from age 25 to 64 years. Measurements of neck strength taken in upright position with the DBC 140 equipment have almost perfect intra- and inter-tester reliability and justify the use of this test procedure. The use of the first measurement in a test series can be recommended for use in clinical practice since it was shown to be the maximal test value and thus, had a very low intra-tester difference. The use of reference values for neck strength when evaluating patients with neck disorders needs to take gender into account.

Reproducibility of isometric strength: measurement of neck muscles

Objective. To evaluate the repeatability of an advanced method of measuring the strength of functionally different groups of neck muscles using an isometric apparatus. Design. A repeated measures design was used within and between sessions. Background. Chronic neck pain has been associated with poor isometric neck strength. In rehabilitation, strength measurements may thus help to evaluate the basic condition and show whether or not treatments and exercises have been beneficial for improving strength. Previous tests have concentrated on testing strength while trying to bend forwards and backwards, but no biomechanics device, able to test rotator muscles, has been presented. Method. The new isometric measurement device was used to test flexion, extension and also rotation strengths of normal subjects ( n = 33). Results. Intratester repeatability was good with regard to all measured parameters. Conclusions. With both tests performed on the same day and test comparisons between days, intratest repeatability was good with regard to all measured parameters.