Isometric Neck Muscle Strength Research Articles

A Prospective Cohort Study on Risk Factors for Cervico-Thoracic Pain in Military Aircrew.

BACKGROUND: Military aircrew frequently report cervico-thoracic pain and injury. The relationship between risk factors and future pain episodes is, however, uncertain. The aim of this study was to identify risk factors for cervico-thoracic pain and to determine the 1-yr cumulative incidence of such pain.METHODS: A total of 47 Swedish aircrew (fighter and helicopter pilots and rear crew) without pain in the cervico-thoracic region were surveyed about work-related and personal factors and pain prevalence using the Musculoskeletal Screening Protocol questionnaire. They also performed tests of movement control, active cervical range of motion, and isometric neck muscle strength and endurance. Aircrew were followed for a year with questionnaires. Logistic regressions were used to identify potential risk factors for future cervico-thoracic pain.RESULTS: Previous cervico-thoracic pain (OR: 22.39, CI: 1.79-280.63), lower cervical flexion range of motion (OR: 0.78, CI: 0.64-0.96), and lower neck flexor muscular endurance (OR: 0.91, CI: 0.83-0.99) were identified as risk factors for reporting cervico-thoracic pain. At follow-up, 23.4% (CI: 13.6-37.2) had reported cervico-thoracic pain during the 12-mo follow-up period.DISCUSSION: The Musculoskeletal Screening Protocol can identify risk factors for cervico-thoracic pain. The link between cervico-thoracic pain and previous pain, as well as lower performance of neck range of motion and muscular endurance, highlights the need for primary and secondary preventive action. The findings from this study can facilitate the development of such pain prevention programs for aircrew.Tegern M, Aasa U, Larsson H. A prospective cohort study on risk factors for cervico-thoracic pain in military aircrew. Aerosp Med Hum Perform. 2023; 94(7):500-507.

A Flight Helmet-Attached Force Gauge for Measuring Isometric Neck Muscle Strength.

INTRODUCTION: Fighter pilots must withstand high Gz-forces that can damage the cervical spine. Strength of the cervical musculature is of vital importance when it comes to preventing these G-induced neck injuries. However, there is very little evidence on valid neck muscle strength measurement methods for fighter pilots. The aim of this study was to examine the validity of a commercial force gauge attached to a pilot's helmet for measuring isometric neck muscle strength.METHODS: A total of 10 subjects performed maximal isometric cervical flexion, extension, and lateral flexion with the helmet-attached gauge and with a weight stack machine, which was used as a reference. Electromyography (EMG) activities were recorded from the right and left sternocleidomastoids and cervical erector spinae muscles during all measurements. Paired t-tests, Pearson correlation coefficient, and Wilcoxon's test were used to analyze the data.RESULTS: Difference of mean force values between the devices was statistically significant in all directions. Pearson correlation coefficient varied between 0.73 and 0.89 and it was highest in cervical flexion. EMG activities were significantly different only in the left CES during flexion.DISCUSSION: The helmet-attached gauge is a valid tool for measuring isometric neck muscle strength and is best used as a means to compare individual differences in strength levels or to track the progress of strength development.Nyländen P, Virmavirta M, Sovelius R, Kyröläinen H, Honkanen T. A flight helmet-attached force gauge for measuring isometric neck muscle strength. Aerosp Med Hum Perform. 2023; 94(6):480-484.

Associations of neck muscle strength and cervical spine\xa0mobility with future neck pain and disability: a prospective 16-year study

BackgroundNeck pain has been associated with weaker neck muscle strength and decreased cervical spine range of motion. However, whether neck muscle strength or cervical spine mobility predict later neck disability has not been demonstrated. In this 16-year prospective study, we investigated whether neck muscle strength and cervical spine mobility are associated with future neck pain and related disability in women pain-free at baseline.MethodsMaximal isometric neck muscle strength and passive range of motion (PROM) of the cervical spine of 220 women (mean age 40, standard deviation (SD) 12 years) were measured at baseline between 2000 and 2002. We conducted a postal survey 16 years later to determine whether any subjects had experienced neck pain and related disability. Linear regression analysis adjusted for age and body mass index was used to determine to what extent baseline neck strength and PROM values were associated with future neck pain and related disability assessed using the Neck Disability Index (NDI).ResultsThe regression analysis Beta coefficient remained below 0.1 for all the neck strength and PROM values, indicating no association between neck pain and related disability. Of the 149 (68%) responders, mean NDI was lowest (3.3, SD 3.8) in participants who had experienced no neck pain (n = 50), second lowest (7.7, SD 7.1) in those who had experienced occasional neck pain (n = 94), and highest (19.6, SD 22.0) in those who had experienced chronic neck pain (n = 5).ConclusionsThis 16-year prospective study found no evidence for an association between either neck muscle strength or mobility and the occurrence in later life of neck pain and disability. Therefore, screening healthy subjects for weaker neck muscle strength or poorer cervical spine mobility cannot be recommended for preventive purposes.

Exploring the Effectiveness of Acupuncture as an Adjunct to Physiotherapy in the Treatment of Musculoskeletal Conditions: A Systematic Review

Background: Acupuncture is one of the most popular forms of complementary and alternative medicine, and its usage is linked to an improvement of physical and psychological symptoms. Main Objectives: Determine whether the use of acupuncture as an adjunct to physiotherapy treatment is more effective than physiotherapy alone or acupuncture alone in MSK conditions. Methodology: A systematic review of the literature was conducted using three major databases, from March 2019 to May 2019, i.e., Cochrane Library, PubMed, and PEDro (Physiotherapy Evidence Database). The inclusion criteria were limited to randomized controlled trials (RCT) published in English, only studies published within the past decade, and investigating adult populations with MSK conditions. Results: From the 227 titles and abstracts that were identified, 75 were duplicates, leaving us with 152 studies for the initial screening. Eight studies [13-20] were included in this review for a qualitative analysis. The studies that assessed pain did not found statistically significant results that support the combination of physiotherapy and acupuncture, the same results were also obtained for Range of motion in knee osteoarthritis. Muscular tension was found statistically significant within-group improvements for all parameters in comparison with the baseline. For Isometric Neck Muscle Strength (INMS), the studies reported significant improvements within the groups, with Physiotherapy combined with Acupuncture being more effective than Acupuncture or Physiotherapy alone. The Constant Shoulder Assessment (CSA), for shoulder function was significantly higher in the exercise plus acupuncture group compared with the exercise group. Conclusion: As an integrative or complementary therapy for pain, acupuncture has been increasingly used. However, this review did not find significant evidence to support that the addition of acupuncture to physiotherapy treatment has an added benefit to pain relief. This review did, however, find benefits of adding acupuncture to treatment to reducing neck disability and improving muscular strength and shoulder function.

Neck Muscle Strength and Mobility of the Cervical Spine as Predictors of Neck Pain

Follow-up study. To study whether neck muscle strength or cervical spine mobility values could serve as predictors for future neck pain among originally pain-free working-age subjects during a long period. Neck pain has been associated with weaker neck muscle strength and lower cervical spine mobility in several studies. However, causality between physical capacity and neck pain has not been shown. Isometric neck muscle strength and passive range of motion of the cervical spine of 220 healthy female volunteers, aged 20 to 59 years, were measured. A postal survey was conducted 6 years later to determine whether any volunteers had experienced neck pain. The receiver operator characteristics curve was used to study how well the neck strength and mobility values in different movement planes at baseline served as predictors of future neck pain. Of the 192 (87%) responders, 37 (19%) reported neck pain for 7 days during the past year. In predicting neck pain, areas under the receiver operator characteristics curves (95% confidence intervals) in different movement planes were 0.52 to 0.56 (0.41-0.66) for isometric neck strength and 0.54 to 0.56 (0.44-0.76) for passive mobility of the cervical spine. The results suggest that neither isometric neck muscle strength nor passive mobility of cervical spine has predictive value for later occurrences of neck pain in pain-free working-age women. Thus, screening healthy subjects for weaker neck muscle strength or decreased mobility of the cervical spine may not be recommended for preventive purposes.

Neck Strength, Position Sense, and Motion in Military Helicopter Crew With and Without Neck Pain

Neck pain in military helicopter pilots and rear aircrew is an occupational health problem that may interfere with flying performance. The aim of the present study was to investigate possible differences in the physical abilities of the cervical spines of helicopter pilots and rear aircrew with and without neck pain during the previous year. The study included 61 male helicopter pilots and 22 rear aircrew without neck pain (Sx-) and 17 pilots and 17 rear aircrew with neck pain (Sx+). Active cervical range of motion (flexion-extension, right-left rotation, and right-left lateral flexion), neck position sense (reposition error back to neutral and defined positions after submaximal cervical movement), and maximum isometric neck muscle strength (flexion, extension, and right and left lateral flexion) were measured. Two-way factorial analyses of variance were performed, in which the fixed factors were occupation (pilot or rear aircrew) and neck pain state (Sx+ or Sx-). On average, there was a trend toward lower values in strength [extension: 55 (19) Nm vs. 58 (20) Nm; flexion 22 (8) Nm vs. 24 (12) Nm] and smaller cervical range of motion [flexion-extension: 132 degrees (19 degrees) vs. 137 degrees (15 degrees); rotation: 156 degrees (14 degrees) vs. 160 degrees (14 degrees)] in the total Sx+ crew, compared to their Sx- colleagues. However, the two-way factorial ANOVA revealed neither significant main effects nor significant interaction effects in any of the measured physical abilities. The results suggest that having experienced neck pain was not significantly associated with differences in the physical abilities of the cervical spines of helicopter crew, as assessed in this study.

Tension neck syndrome treated by acupuncture combined with physiotherapy: A comparative clinical trial (pilot study)

To evaluate the effect of acupuncture combined with physiotherapy in comparison with acupuncture and physiotherapy performed alone in different parameters; pain intensity, muscle tension, functional disability and muscle strength in the treatment of tension neck syndrome (TNS). A prospective, comparative clinical trial. Acupuncture and Rehabilitation Department. TNS can occur in computer users. Acupuncture has been one alternative treatment in physiotherapeutic rehabilitation of musculoskeletal disorders. Forty-six patients with TNS. Patients were allocated into three groups: Group-1 received physiotherapy (therapeutic exercises) combined with acupuncture; Group-2, acupuncture alone, and Group-3, physiotherapy alone; over a period of 10 weeks, with one or two sessions weekly. All patients had completed the protocols and were assessed using a visual analogue scale for pain intensity (VASpain) and muscle tension (VASmt), the Neck Disability Index: Brazilian Portuguese version for functional disability, and the cranio-cervical Flexion Test for isometric neck muscle strength (INMS); in the periods before treatment (baseline), after 10 weeks of treatment, and after 6 months of follow-up. All groups showed significant improvement (p < 0.001) in these parameters after 10 weeks of treatment and after 6 months of follow-up. Group-1 was superior to Group-3 in pain and functional disability improvements (p<0.05); and Group-1 was superior to both Group-2 (p < 0.01) and Group-3 (p < 0.05) in INMS. After 6 months of follow-up, the improvements of all groups were maintained (p < 0.05). The data suggested that acupuncture effect may facilitate and/or enhance physiotherapy performance in musculoskeletal rehabilitation for tension neck syndrome.

Differences in Isometric Neck Muscle Strength Between Healthy Controls and Women With Chronic Neck Pain: The Use of a Reliable Measurement

Cagnie B, Cools A, De Loose V, Cambier D, Danneels L. Differences in isometric neck muscle strength between healthy controls and women with chronic neck pain: the use of a reliable measurement. Objectives To determine the intra- and interrater reliability of the Biodex isokinetic dynamometer to measure the maximal isometric strength of the cervical flexors and extensors, to develop an age- and sex-based normative database in a healthy population, and to evaluate the differences in neck strength between women with chronic neck pain and healthy controls. Design Cross-sectional. Setting Physical and rehabilitation medicine department. Participants Ninety-six healthy volunteers (4 age groups: 20–29, 30–39, 40–49, 50–59y; each consisting of 12 men and 12 women) and 30 women with chronic neck pain. Interventions Not applicable. Main Outcome Measures Peak isometric strength of the cervical muscles was tested for flexion and extension by using the Biodex isokinetic dynamometer. The intra- and interrater reliability of the protocol was evaluated in 12 volunteers. Results The reliability for strength was high for both flexion and extension (intraclass correlation coefficient, .92–.96). The mean peak torque for flexion and extension was significantly higher in men (24Nm, 36.4Nm, respectively) compared with women (16.6Nm, 26.5Nm, respectively) ( P<.001). Peak torque production for extension was significantly lower in the patient group (22.3Nm) compared with the healthy female control group (26.5Nm) ( P=.003). No significant differences in flexion strength between patient and female control group were found. Conclusions Results show a high degree of intra- and interrater reliability in measuring isometric neck muscle strength when using the Biodex isokinetic dynamometer. The use of normative data for neck strength when evaluating patients with neck disorders needs to take sex into account. The current study has shown that women with chronic neck pain have lower neck muscle strength in extension than the healthy female group.

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.

A randomized clinical trial of TENS and exercise for patients with chronic neck pain

To investigate the effect of transcutaneous electrical nerve stimulation (TENS) on acupuncture points and neck exercise in chronic neck pain patients. A randomized clinical trial. Hospital-based practice. Two hundred and eighteen patients with chronic neck pain. Subjects were randomized into three groups, receiving either (1) TENS over the acupuncture points plus infrared irradiation (TENS group); (2) exercise training plus infrared irradiation (exercise group); or (3) infrared irradiation alone (control); twice a week for six weeks. The values of verbal numeric pain scale, Northwick Park Neck Pain Questionnaire, and isometric neck muscle strength were assessed before, at the end of the six-week treatment, and at the six-month follow-up. Results demonstrated that after the six-week treatment, significant improvement in the verbal numerical pain scale was found only in the TENS group (0.60+/-2.54, p = 0.027) and the exercise group (1.57+/-2.67, p < 0.001). Though significant reduction in Northwick Park Neck Pain Questionnaire score was found in all three groups, post-hoc tests showed that both the TENS and the exercise group produced better improvement (0.38+/-0.60% and 0.39+/-0.62% respectively) than the control group (0.23+/-0.63%). Significant improvement (p = < 0.001 to 0.03) in neck muscle strength was observed in all three groups, however, the improvement in the control group was not clinically significant and it could not be maintained at the six-month follow-up. After the six-week treatment, patients in the TENS and exercise group had a better and clinically relevant improvement in disability, isometric neck muscle strength, and pain. All the improvements in the intervention groups were maintained at the six-month follow-up.

A Randomized Controlled Trial on the Efficacy of Exercise for Patients With Chronic Neck Pain

A randomized controlled trial with single-blind outcome assessments. To evaluate the efficacy of a neck exercise program in patients with chronic neck pain. The effect of exercise for patients with chronic neck pain has been investigated in a number of studies. The efficacy is, however, questionable. A total of 145 patients were randomly allocated into an exercise (n = 67) and a nonexercise (control) group (n = 78). Patients in the control group were given infrared irradiation and neck care advice. In addition to infrared irradiation and advice, patients in the exercise group had undergone an exercise program with activation of the deep neck muscles and dynamic strengthening of the neck muscles for 6 weeks. Subjective pain and disability and isometric neck muscle strength were measured at baseline, 6 weeks, and 6 months. Analysis was by intention-to-treat. At week 6, the exercise group had a significantly better improvement in disability score (P = 0.03), subjective report of pain (P = 0.01), and in isometric neck muscle strength (P = 0.57-0.00) in most of the directions than the control group. However, significant differences between the two groups were found only in the subjective report of pain and patient satisfaction at the 6-month follow-up. At week 6, patients with chronic neck pain can benefit from the neck exercise program with significant improvement in disability, pain, and isometric neck muscle strength in different directions. However, the effect of exercise was less favorable at 6 months.

Use of modified Northwick Park Neck Pain Questionnaire in patients with postirradiation neck disability: Validation study

No available measure exists for postirradiation neck disability. Adoption of the Chinese Northwick Park Neck Pain Questionnaire (NPQ) for patients with postirradiation neck disability was examined in this study. Eight physiotherapists and five patients were invited to test the validity of the content. Forty-three patients with neck disability were recruited to evaluate test-retest reliability and internal consistency. The level of neck discomfort, range of neck motion and maximal isometric neck muscle strength, and SF-36 health score were measured for construct validity testing. The questionnaire had good content validity, a high degree of test-retest reliability, internal consistency (intraclass correlation coefficient [ICC], 0.94; Cronbach's alpha, 0.88), and good construct validity. NPQ correlated significantly with most of the subscores of SF-36 (r(s), -0.43 to - 0.71) and numeric rating scale (r(s) = 0.69). The modified Chinese NPQ was found to be reliable and valid for the evaluation of postirradiation neck disability.

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.

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.

Maximal isometric muscle strength of the cervical spine in healthy volunteers.

To describe the maximal isometric neck muscle strength in healthy Chinese volunteers, in six different directions, as measured by a Multi Cervical Rehabilitation Unit. A standardized cross-sectional observational study. A university rehabilitation unit. Ninety-one healthy volunteers aged 20-84. During the measurement the subject was instructed to do three consecutive steady contractions as hard as possible, with a 10-second rest in between each contraction and a 2-minute rest between different directions. The peak isometric strength for each of the six directions (flexion, extension, lateral flexions, protraction and retraction) was calculated. No significant difference was found in muscle strength between different age groups. Isometric muscle strength in the direction of right lateral flexion was significantly greater than that to the left in men (p = 0.030), but no difference was found in women (p = 0.297). Isometric strength in all directions in men was 1.2-1.7 times that in women (all p < 0.028). Correlations between physical measurements (height and weight) and strength values were all insignificant in both genders. Men have approximately 20-70% greater isometric neck muscle strength than women. Both men and women can maintain high levels of cervical muscle strength in six different directions up to their seventh decade. There is no significant correlation between physical measurements and isometric neck muscle strength.