Trunk extensor and flexor strength measured by the Cybex 6000 dynamometer. Assessment of short-term and long-term reproducibility of several strength variables

Impact of Urinary Incontinence on Physical Function and Respiratory Muscle Strength in Incontinent Women: A Comparative Study between Urinary Incontinent and Apparently Healthy Women

Patients with stress urinary incontinence (SUI) may be afraid to increase intra-abdominal pressure to avoid incontinence. This could lead to weak expiratory muscles. The aim of this study was to investigate the association between respiratory muscle strength, physical function, and SUI in patients with SUI. A cross-sectional study was conducted in the Physical Medicine and Functional Rehabilitation Department. Thirty-one incontinent women (IG) and twenty-nine women in a control group (CG) were enrolled in this study. Anthropometric data, respiratory muscle strength (maximal inspiratory pressure; maximal expiratory pressure), SUI (Urogenital Distress Inventory-6; Incontinence Impact Questionnaire-7; Pad test), and physical function (waist circumference; timed-up-and-go test; abdominal muscle strength) were assessed. Body fat, body mass index, body weight, and waist circumference were higher in IG than CG (p < 0.01), while postural gait and abdominal muscles were lower (p < 0.001). Respiratory muscle strength displayed moderate correlations with SUI severity, especially for maximal expiratory pressure (p < 0.01). Maximal expiratory pressure was moderately associated with physical function. Deterioration in respiratory muscle strength is a characteristic of women with SUI. In this population, pelvic floor muscle training may be prescribed to improve continence. By feeling more confident about increasing intra-abdominal pressure, women with SUI would strengthen their expiratory muscles and eventually improve their physical function.

Core muscle strength can be reliably measured using a novel isokinetic device: An intra-observer study

BACKGROUND

Core strength is an important aspect of physical fitness. A dynamometer was developed to measure isokinetic core muscle strength in multiple planes of motion. Establishing the reliability is needed before it can be used in practice.

OBJECTIVE

Examine the intra-observer reliability of a trunk isokinetic dynamometer.

METHODS

31 participants were recruited. Tests were performed twice with an interval of 5-9 days by the same observer. Testing included rotation, flexion/extension and lateral flexion at speeds of 90∘/s and 60∘/s. The main outcome measure was peak torque (PT). The secondary outcomes included peak torque angle (PTA), time to peak torque (TTPT) and compensatory torques (CompTQ). The intra-observer reliability was investigated using intraclass correlation coefficients (ICC).

RESULTS

Peak torque reliability was good to excellent (ICC = 0.70-0.91), whereas the reliability of the PTA (ICC =-0.04-0.56) and TTPT (ICC = 0.01-0.68) were poor to moderate. CompTQ reliability was moderate to good (ICC = 0.20-0.88).

CONCLUSIONS

The intra-observer reliability of the isokinetic measurement of core strength peak torque was good. The secondary outcomes peak torque angle and time to peak torque were less reliable and the compensatory torques showed moderate to good reliability. This isokinetic dynamometer could have useful applications in the field of sports medicine and rehabilitation.

Reliability and agreement of isometric functional trunk and isolated lumbar strength assessment in healthy persons and persons with chronic nonspecific low back pain

OBJECTIVES

to assess intra/inter-operator reliability and agreement of maximum isometric abdominal and back muscle strength in a functional trunk and isolated lumbar protocol, using an isokinetic dynamometer, in healthy persons and persons with chronic nonspecific low back pain (CNSLBP).

DESIGN

Test-retest.

SETTING

Participants performed two assessments consisting of two protocols on the Biodex 3 system, evaluating maximum isometric back and abdominal strength in a functional trunk and isolated lumbar position. During the first assessment, each protocol was executed twice, supported by different operators.

PARTICIPANTS

Healthy persons (n = 20) and persons with CNSLBP (n = 20).

MAIN OUTCOME MEASURES

Intraclass Correlation (ICC), Standard Error of Measurement (SEM and %SEM), and Minimal Detectable Change (MDC) of muscle strength outcomes and seat positioning characteristics were calculated.

RESULTS

Intra/inter reliability of muscle strength outcomes was excellent (ICC: 0.94-0.98), while seat positioning characteristics varied from low to high (ICC: 0-0.94). For muscle strength outcomes, %SEM ranged from 4.7 to 9.2% and MDC ranged from 14.3 to 29.8 Nm in trunk flexion and 39.1-68.5 Nm in trunk extension.

CONCLUSIONS

The Biodex 3 system can be used reliably to assess maximum isometric trunk muscle strength with the aforementioned protocols in healthy persons and persons with CNSLBP. All muscle strength outcomes showed comparable agreement (%SEM < 10%).

Trunk flexor and extensor muscle performance in chronic stroke patients: a case-control study

BACKGROUND

Although chronic stroke patients commonly show impairment of trunk muscle performance, this disability has only been analyzed in terms of peak torque. Therefore, other measures are needed for a more adequate description.

OBJECTIVE

This study aimed to compare concentric muscle performance of trunk flexor/extensor muscles between chronic stroke patients and matched-healthy subjects.

METHODS

18 chronic stroke patients and 18 healthy subjects were matched according to their age, sex, body mass index and level of physical activity. After familiarization, trunk flexor/extensor concentric muscle strength was measured using an isokinetic dynamometer (Biodex Medical Systems Inc, Shirley, NY, USA) with 3 repetitions at a velocity of 60°/s and 5 repetitions at a velocity of 120°/s. Trunk muscular performance was characterized by peak torque, torque at 90°, total work, and total work normalized by trunk mass. Student's t-test was used for independent samples (α=0.05) for group comparisons.

RESULTS

All trunk muscle performance variables values investigated were significantly lower in chronic stroke patients when compared to matched-healthy subjects (p≤0.001). The obtained ratios of chronic stroke patients scores to that of the matched-healthy subjects at velocities of 60°/s and 120°/s were, respectively: flexor peak torque (60% & 53%)/extensor (54% & 53%); flexor torque at 90° (56.20% & 36.58%)/extensor (57.92% & 30.65%); flexor total muscular work (51.27% & 38.03%)/extensor (47.97% & 39.52%); and flexor total muscular work normalized by trunk mass (55.57% & 40%)/extensor (51.40% & 42%).

CONCLUSIONS

Chronic stroke patients showed decreased trunk muscle performance when compared to matched-healthy subjects in all variables investigated.

Test-retest reliability of the disease activity score 28 CRP (DAS28-CRP), the simplified disease activity index (SDAI) and the clinical disease activity index (CDAI) in rheumatoid arthritis when based on patient self-assessment of tender and swollen joints

Composite disease activity scores are frequently used in daily practice as tools for treatment decisions in patients with rheumatoid arthritis (RA). If reliable, patient-reported disease activity may be time saving in the busy clinic. The objective was to examine the test-retest reliability of the Disease Activity Score 28 CRP (DAS28-CRP) with four variables (4v) and three variables (3v), the Simplified Disease Activity Index (SDAI) and the Clinical Disease Activity Index (CDAI) when based on patient self-assessment of tender and swollen joints and to examine the agreement between these scores and physician-derived scores. Thirty out-clinic RA patients with stable disease were included. A joint count was performed two times 1 week apart by the patient and by an experienced physician. Test-retest reliability was expressed as the least significant difference (LSD), as the LSD in percent of the mean score (%LSD) and as intra-individual coefficients of variation (CVi). Mean scores based on physician vs. patient joint counts (visit 1) were: DAS28-CRP(4v) 3.5 ± 1.0 vs. 3.6 ± 1.1 (not significant (NS)), DAS28-CRP(3v) 3.4 ± 0.9 vs. 3.5 ± 0.9 (NS), SDAI 14.2 ± 9.4 vs.14.1 ± 9.4 (NS) and CDAI 13.4 ± 9.3 vs. 13.3 ± 9.4 (NS). The LSDs (%LSD) for duplicate assessments of patient-derived scores (visit 2 vs. 1) were: DAS28-CRP(4v) 0.8 (23.2), DAS28-CRP(3v) 0.9 (25.2), SDAI 8.3 (59.9) and CDAI 8.4 (63.8). Similar LSDs were found for differences between duplicate assessments of physician-derived scores and for differences between physician and patient-derived scores. CVis for SDAI and CDAI were significantly higher than for DAS28-CRP(4v) and DAS28-CRP(3v) (p < 0.005). Patient- and physician-derived scores agreed closely on group level. On the individual level, the LSDs between patient- and physician-derived scores were considerable but corresponded to both patient and physician intra-observer LSDs. Thus, scores based on patient-performed joint counts may be an alternative to traditional physician-derived scores in patients with stable disease.

Isokinetic assessment of the shoulder rotators: a study of optimal test position

BACKGROUND

  Isokinetic assessment of the shoulder rotator cuff is a common component of shoulder muscles assessment. Nevertheless, the extensive mobility of the shoulder poses great difficulty in finding a consensus protocol for evaluation.

OBJECTIVE

  To select an optimal protocol, among three, based on the best reproducibility and reliability of strength scores derived from internal and external rotator tests.

METHOD

  The dominant side external and internal rotator muscles of twelve healthy male subjects were evaluated based on a concentric protocol (60° s(-1) and 240° s(-1) ) in three different test positions: two in lying supine with the arm in either 90° or 45° abduction and one in the seated position with the arm moving in the scapular plane on the dominant shoulder. Subjects were tested twice over 10 days.

RESULTS

  The two lying installations were associated with the lowest coefficient of variation (7.1-11.8%) and smallest detectable difference (7-15.9 N.m) for peak moment and strength ratios. Consequently, the lying positions were chosen for rotators assessment with 90° of abduction associated with a higher reproducibility for the agonist/antagonist ratios or 45° if some pain was provoked. In any case, the coefficient of variation did not exceed 12%.

CONCLUSION

  Based on a reproducibility and reliability analysis, we recommend the testing of isokinetic strength of the shoulder rotators to be conducted in supine lying, with the arm at 90° or 45° abduction in the frontal plane.

Reproducibility of isokinetic peak torque assessments of the hip flexor and extensor muscles

OBJECTIVES

Isokinetic assessment is currently the reference method for measuring dynamic muscle strength. We have sought to evaluate the reproducibility over time of isokinetic testing of the hip flexor (FI) and extensor (Ext) muscles and to establish whether there is a significant difference in peak torque (PT) between the left and right hips.

PATIENTS AND METHODS

Ten adults were tested once a week for 3 weeks by the same investigator and according to the same protocol, with two velocities (60 degrees /s and 180 degrees /s) for the hip FI and Ext in concentric tests and one velocity (30 degrees /s) for the Ext only in eccentric tests. The reproducibility of the measured PT was analyzed by using the intraclass correlation coefficient (ICC) and a Bland and Altman plot. The difference in PT between the right and left hips was tested using Student's T test.

RESULTS

The ICC for the observed PT values revealed very good reproducibility (with a value of between 0.75 and 0.96) for the hip FI and Ext measurements (regardless of the body side, test velocity or contraction mode). We did not observe any significant PT differences between the right and left hips.

CONCLUSION

The isokinetic assessment of the concentric and eccentric PT values generated by the hip FI and Ext is highly reproducible. There is no difference between dominant and nondominant body sides, which enables the use of the contralateral limb as a reference.

Age, weight, and the front abdominal power test as predictors of isokinetic trunk strength and work in young men and women

First we tested the reliability of two new field tests of core stability (plank to fatigue test [PFT] and front abdominal power test [FAPT]), as well as established measures of core stability (isokinetic trunk extension and flexion strength [TES and TFS] and work [TEW and TFW]) over 3 days in 8 young men and women (24.0 +/- 3.1 years). The TES, TFS, TFW, and FAPT were highly reliable, TEW was moderately reliable, and PFT were unreliable for use during a single testing session. Next, we determined if age, weight, and the data from the reliable field test (FAPT) were predictive of TES, TEW, TFS, and TFW in 50 young men and women (19.0 +/- 1.2 years). The FAPT was the only significant predictor of TES and TEW in young women, explaining 16 and 15% of the variance in trunk performance, respectively. Weight was the only significant predictor of TFS and TFW in young women, explaining 28 and 14% of the variance in trunk performance, respectively. In young men, weight was the only significant predictor of TES, TEW, TFS, and TFW, and explained 27, 35, 42, and 33%, respectively, of the variance in trunk performance. In conclusion, the ability of weight and the FAPT to predict TES, TEW, TFS, and TFW was more frequent in young men than women. Additionally, because the FAPT requires few pieces of equipment, is fast to administer, and predicts isokinetic TES and TEW in young women, it can be used to provide a field-based estimate of isokinetic TES and TEW in women without history of back or lower-extremity injury.

Trunk muscular strength in pre-pubertal children with and without back pain

OBJECTIVE

While in adulthood there is no proven relationship between back pain and trunk muscle strength, in pre-pubertal subjects this topic has been poorly studied. The aim of the study was to evaluate isometric and isokinetic trunk muscle strength in children with or without previous back pain.

METHODS

The recent occurrence of back pain (last 6 months) among 144 children (77 males, 67 females, age 11.9 +/- 0.3 years) was assessed using a questionnaire. Extensor and flexor trunk muscle strength was measured through isometric and isokinetic (60, 90, 120 degrees/s) tests. Peak torque (PT), PT angle, PT flexor/PT extensor ratio and intra-session coefficient of variation (COV) were determined.

RESULTS

Flexor and extensor muscle PT, but not PT angle, were significantly higher in males than in females, irrespective of back pain occurrence. PT flexor/PT extensor ratio at 90 degrees angular velocities increased significantly only in males with back pain, compared with males without back pain. The COV trend was similar for flexor and extensor muscles.

CONCLUSIONS

Isometric and isokinetic trunk muscle strength probably play a minor role in back pain occurrence in children. The isokinetic testing velocity may be important in determining trunk strength differences between children with and without back pain.

The value of physical performance tests for predicting therapy outcome in patients with subacute low back pain: a prospective cohort study

Considering the enormous costs of intensive multidisciplinary treatment, predictive tests for therapy outcome are needed to evaluate patients' performance potential and increase cost effectiveness. Somatic parameters are commonly used to evaluate health status and serve as an additional means of forecasting the prognosis, yet little is known of their validity. In this study, we investigated the prognostic value of somatic parameters regarding the outcome of multidisciplinary treatment in patients with subacute low back pain. The study was designed as a prospective cohort study of 162 patients. Somatic parameters were assessed with three physical performance tests (Villiger test, Oesch test, Biering-Sørensen test) before treatment (T0), after 3 weeks' inpatient therapy (T1) and at 6-month follow-up (T2). Psychometric characteristics of subjective pain perception (VAS), a pain disability index (PDI) and a physical capability index (FFbH-R) were recorded. Correlation coefficients between the physical performance test scores and psychometric characteristics were calculated. To predict therapy outcome, discriminant analyses were performed. A control group (n = 30) was evaluated at similar time points without receiving any therapy. Our results demonstrate good discrimination between patients and controls by means of the investigated performance tests and exhibit a significant negative correlation with the psychometric data. Lower outcome values at study entry correlated with higher pain intensity and disability after multidisciplinary treatment. However, the statistical magnitude of correlation was relatively low and further discriminant analysis did not reveal any predictive value. Consequently the physical performance tests do not have a prognostic value regarding therapy outcome.

The Bath metrology index as assessed by a trained and an untrained rater in patients with spondylarthropathy: a study of intra- and inter-rater agreements

The Bath ankylosing spondylitis metrology index (BASMI; range 0-10) has gained widespread use in daily clinical practice as an objective measure of spinal stiffness not only in patients with ankylosing spondylitis (AS) but also in patients with other spondylarthropathies (SpA). We examined intra-rater and inter-rater reproducibility of BASMI scoring in 30 Danish patients with SpA (median age 40 years, range 22-56 years) fulfilling the European Spondylarthropathy Study Group criteria, 25 of them satisfying the modified New York Criteria for AS. Measurements were performed twice on two different days (median interval 7 days, range 4-11) by a trained physiotherapist (PT) and by an untrained nurse who had undergone a single 1-h training session with the PT. The median BASMI score obtained by the PT on the two test days was 3.5 (range 1-8) and 3.0 (range 1-8), respectively (NS). Test-retest BASMI scores from the PT were significantly correlated (r(s) = 0.95, p < 0.0001). The 95% likely range for the difference between a patient's BASMI scores from two tests was +/-1.4 corresponding to a minimal detectable difference of +/-2 in the individual patient as the scale consists of intervals of 1. Similar results were achieved by the nurse. BASMI scores obtained by the two raters were significantly inter-correlated (r(s) = 0.95, p < 0.0001). The mean difference between paired BASMI scores obtained by the nurse and the PT on test day 1 was -0.2 with a minimal detectable difference of +/-2. A similar result was found using data from test day 2. In conclusion, a change in BASMI less than 2 may be due solely to expected random measurement error. A single 1-h training session allowed an untrained nurse to obtain BASMI results almost identical to those of an experienced PT.

Grip and pinch strength in healthy subjects and patients with primary osteoarthritis of the hand: a reproducibility study

Grip, Key Pinch (KP), 3 Point Pinch (3PP) and 2 Point Pinch (2PP) strengths were measured twice weekly in 32 women with primary osteoarthritis of the hand (POAH) and 25 healthy women. Reproducibility was assessed by standard error of measurement (SEM) and the coefficient of variation (CV). Cutoff values for significant improvement or deterioration were determined and expressed, respectively, as either the smallest detectable difference (SDD) or critical difference (CD). The SDD and CD of grip and pinch strengths were higher in POAH patients than in the healthy group. Among the pinch tests the 2PP findings were least reproducible. The relatively high SDD and CD scores indicate that improvement may be detected only in patients with moderate to severe weakness of grip and pinch. Furthermore, in POAH patients, diagnosing strength changes using the 2PP test is invalid due to low reproducibility.

Reproducibility of Pressure Pain Threshold and Visual Analog Scale Findings in Chronic Whiplash Patients

BACKGROUND

Assessment of pain in patients with whiplash-associated disorders has been previously reported using a variety of instruments. However, the reproducibility of the findings derived from such measurements has not been explored with respect to this particular patients group.

OBJECTIVES

To evaluate the intratester and intertester reproducibility of pressure pain threshold (PPT) findings and the intratester reproducibility of visual analog scale (VAS) findings relating to the cervical region of chronic whiplash patients for the determination of smallest real difference values.

METHODS

Twenty-one chronic whiplash patients: 13 women and 8 men participated in this study. The intratester paradigm was based on 2 testing sessions over a period of 5 to 11 days (7.95+/-1.90) and incorporated recording of VAS scores and also PPT scores relating to 3 pairs of right and left homologous cervical sites. The intertester study was conducted within the first testing session and referred to the PPT measurement only. In this session, patients were also asked to fill in the Neck Disability Index questionnaire.

RESULTS

The interclass correlation coefficient-derived reproducibility of the PPT scores was good to excellent within and between testers ranging 0.85 to 0.91 and 0.88 to 0.97, respectively. There was, however, a significant difference between the testers. The VAS scores demonstrated lower reproducibility (interclass correlation coefficient=0.67). On the basis of the standard error of measurement, the smallest real difference of PPT ranged 40.2 to 58.9 kPa whereas the corresponding figure for the VAS was 3.76 cm.

CONCLUSIONS

On the basis of the current patient sample, this study demonstrates that although PPT findings may generally be applied for monitoring change in chronic whiplash patients, the use of VAS scores should be limited to patients whose initial score is above 4. It is also suggested that if the PPT is to serve as an outcome measure, its measurement should be performed by the same tester.

Quadriceps and hamstring isokinetic strength and electromyographic activity measured at different ranges of motion: a reproducibility study

Isokinetic strength measurements of the quadriceps and hamstring that are commonly conducted using a 90 degrees range of motion (RoM) may involve some risk to specific knee patient groups. Testing these muscles at a much shorter RoM may reduce the risk but in order to render this method clinically acceptable the reproducibility of the derived test findings has to be established. Therefore the main objective of this study was to assess the reproducibility of isokinetic peak torque and normalized EMG scores of these muscles based on 90 degrees (0-90 degrees flexion, LR) and three successive short RoMs: 0-30 degrees (SR1), 30-60 degrees (SR2) and 60-90 degrees (SR3). Eight healthy subjects were tested three times with a 2 week between-session interval. All tests were performed on the dominant limb and consisted of maximal concentric and eccentric exertions. The velocities applied were 90 degrees /s for LR and 30 degrees /s for each of the SRs. Findings indicated no between-session improvement in strength. Based on the coefficient of variation the measurement error for all isokinetic strength scores remained stable throughout the testing sessions ranging 0.6-13.9% with the absolute majority of instances less than 10%. The reproducibility of the EMG scores was poorer ranging 1.5-25% and 0.5-19% for the quadriceps and hamstring, respectively. It is concluded that testing of knee muscles at short (30 degrees ) RoMs does not compromise the reproducibility of the strength or EMG scores derived from the commonly used RoM of 90 degrees . However, whereas strength was reproducible to within the accepted clinical standards, the corresponding EMG scores were characterized by a wider error band.

Reliability of the Assessment of Lumbar Range of Motion and Maximal Isometric Strength

OBJECTIVE

To examine the interobserver reliability and intrasubject variability of the assessment of lumbar range of motion (ROM) and maximal isometric strength in asymptomatic subjects by using commercially available equipment.

DESIGN

A cross-sectional repeated-measures design.

SETTING

Ambulatory care in a university hospital.

PARTICIPANTS

Convenience sample of 61 asymptomatic healthy subjects aged 20 to 55 years.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Six movements of the lumbar spine were assessed with commercially available equipment. Both the ROM and the maximal isometric strength for flexion, extension, lateroflexion, and rotation of the lumbar spine were assessed by 2 investigators who were blinded to the outcome of the assessment performed by their colleague.

RESULTS

The intraclass correlation coefficient (ICC) was above .95 for all the strength measurements. For the assessment of the ROM of the lumbar spine, the ICC varied between .77 and .94. There was a significant intrasubject variability for 8 of 12 measurements.

CONCLUSIONS

The interobserver reliability is excellent for the measurement of the maximal isometric strength and good for the assessment of the ROM of the lumbar spine. There is a significant intrasubject variability, which requires the use of the mean or the best value of different trials.

Repeated ankle sprains and delayed neuromuscular response: acceleration time parameters

STUDY DESIGN

A comparative study.

OBJECTIVES

To assess whether in subjects with unilateral chronic ankle instability the dynamic reaction time of the affected ankle differs from the healthy ankle and from ankles of a control group.

BACKGROUND

Reaction time is an essential element in joint protection against sudden unexpected excessive movement requiring fast and coordinated muscle action. During a sudden ankle inversion movement, a reflex action of the evertor muscles is needed to counteract the movement. Adequate neuromuscular response is crucial and a delayed response could contribute to inversion trauma and subsequently to chronic ankle instability. The isokinetic dynamometer acceleration time (ACC-TIME) provides valuable information on dynamic neuromuscular ability.

MATERIAL AND METHODS

Patients with unilateral chronic ankle instability (n = 11) and healthy individuals in a control group (n = 11) were tested on an isokinetic dynamometer during 3 sets of 3 reciprocal inversion/eversion movements of both ankles at 30 degrees/s and 120 degrees/s. Analysis of variance models were used to compare the ACC-TIME of the affected ankle to the unaffected ankle of the same subjects and a control group.

RESULTS

For the evertor muscles at 30 degrees/s and 120 degrees/s a significantly prolonged ACC-TIME was found when comparing the affected ankles to the contralateral ankles and both ankles of the control group. For the invertor muscles at 120 degrees/s a significantly prolonged ACC-TIME was found when comparing the affected ankle to the unaffected ankles of patients and those of the control group.

CONCLUSIONS

Because the most important evertor muscles are innervated by the fibular nerve, the significantly prolonged ACC-TIME of the affected ankle is consistent with the finding of a lower motor nerve conduction velocity of the fibular nerve after inversion trauma. The results support the concept of a delayed neuromuscular response as an important factor in the etiology of chronic ankle instability.

Avaliação isocinética da musculatura envolvida na flexão e extensão do tronco: efeito do método Pilates®

O desequilíbrio entre a função dos músculos extensores e flexores do tronco é um forte indício para o desenvolvimento de distúrbios da coluna lombar. O objetivo do presente trabalho foi avaliar o efeito do método Pilates® sobre a função de extensores e flexores do tronco. Para tanto, foram selecionadas 20 pessoas (16 mulheres com idade média de 34,06 ± 7,21; quatro homens com idade média de 33,5 ± 6,68 anos) com habilidade para executar os exercícios do nível intermediário-avançado, que completaram 25 sessões durante 12 semanas. Os voluntários foram submetidos ao teste isocinético de avaliação da flexão e extensão do tronco no início e ao final do período de treinamento. A função dos extensores do tronco apresentou aumento em todos parâmetros analisados (pico de torque _ 25%, p = 0,0004; trabalho total - 28%, p = 0,0002; potência - 30%, p = 0,0002; quantidade total de trabalho - 21%, p = 0,002) em relação ao período pré-treinamento. Com relação aos músculos flexores, foi detectado discreto aumento para trabalho total (10%, p = 0,0003) e para quantidade total de trabalho (10%, p = 0,002). Analisando a razão flexor:extensor, em todos os parâmetros, foi detectada redução significativa em relação aos índices obtidos no pré-treinamento (pico de torque - 24%, p = 0,0001; trabalho total - 23%, p = 0,002; potência - 25%, p = 0,01; quantidade total de trabalho - 14%, p = 0,04). O método Pilates® (nível intermediário-avançado) mostrou-se uma eficiente ferramenta para o fortalecimento da musculatura extensora do tronco, atenuando o desequilíbrio entre a função dos músculos envolvidos na extensão e flexão do tronco.

Reliability of maximal strength testing in older adults

OBJECTIVES

To determine (1) the reliability of a maximal strength test (1 repetition maximum) [1-RM] in older adults and (2) the impact of differing periods of familiarization.

DESIGN

Within-subject, repeated trials of maximal strength.

SETTING

Community-based senior center.

PARTICIPANTS

Forty-seven independently living men (n=16) and women (n=31), with a mean age of 75.4+/-4.7 years.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Systematic error (shift in mean) and random error (% coefficient of variation [%CV]) was assessed between consecutive pairs of 1-RM trials.

RESULTS

For the bench press, systematic error was virtually eliminated for men between trials 2 and 3 (0.7%; 95% confidence interval [CI], -2.7% to 4.3%). The CV was stable (4.7%-7.3%) across all trials in both genders. For the leg press, a significant but clinically small systematic error (3.6%, P<.05; 95% CI, 0.8-6.6) was evident for women between trials 2 to 3. The CV was reduced across trial pairs by 3.3% for men and 0.9% for women. Three versus 6 or more sessions of familiarization produced small clinical differences in systematic error (< or =4.1%) and CV (< or =0.2%) between trials 2 and 3 for both lifts.

CONCLUSIONS

Reliability is an indispensable requirement for valid test outcomes. Our results show that, in this group of older adults, 3 familiarization sessions and 2 to 3 test trials produced highly reliable 1-RM measures. Additional periods of familiarization added little to test reliability. Effective reliability testing for 1-RM is a practical and attainable goal for outcomes based practitioners.

Reproducibility Indices Applied to Cervical Pressure Pain Threshold Measurements in Healthy Subjects

OBJECTIVES

To apply various statistical indices for reproducibility analysis of pressure pain threshold measurements and to derive a preferred pressure pain threshold measurement protocol based on these indices.

METHODS

The pressure pain threshold of 3 pairs of right and left homologous cervical region sites were measured in 20 healthy subjects (10 women, 10 men) using a hand-held pressure algometer. Measurements took place on 2 occasions (test 1 and test 2) separated by a mean interval of 1 week. On each testing session, the site-related pressure pain thresholds were measured 3 times each according to 2 different protocols. Protocol A consisted of a repetitive order, namely 3 consecutive measurements at each site before proceeding to the next, whereas protocol B consisted of an alternate order in which 3 consecutive rounds of all individually tested sites took place. For test 1, protocol A was followed by protocol B with an hour interval. For test 2, the reverse order took place.

RESULTS

The findings revealed no significant differences between the two protocols and indicated a significant rise (P < 0.0001) in the absolute scores from test 1 to test 2 in both protocols. Absolute values (mean +/-SD) derived from the entire sample of pressure pain threshold sites ranged from 140 +/- 60 to 198.7 +/- 95 kPa (1.60 +/- 0.6 to 1.99 +/- 0.95 kg/cm, respectively). No significant gender or side differences were noted. Pearson r as well as the intraclass correlation coefficient revealed good to excellent reproducibility for both protocols and for all sites measured: r = 0.79-0.94 and intraclass correlation coefficient(3,3) = 0.85-0.96, respectively. To define site-specific cutoff values indicating change at the 95% confidence level, 1.96*SEM was calculated, and its values ranged from 31.6 to 58.2 kPa, which correspond to 16.8% to 32.8% of the absolute mean values. In addition, the limits of agreement, which depict the individual test-retest differences relative to their mean, indicated a heteroscedastic trend.

DISCUSSION

The two protocols yielded very similar results. However, on the grounds of patient's comfort and compliance as well as facility of application, protocol B stands out as the more preferred between the two.

Reliability of computed tomography measurements of paraspinal muscle cross-sectional area and density in patients with chronic low back pain

STUDY DESIGN

A reliability study was conducted.

OBJECTIVE

To estimate measurement errors related to equipment and the observer in computed tomography measurements of cross-sectional area and density of paraspinal muscles. Interobserver reliability was not investigated in the current study.

SUMMARY OF BACKGROUND DATA

Computer tomography (CT) had been used to measure the cross-sectional area and degeneration of the back muscles in patients with low back pain.

METHODS

This study included 31 patients, mean age 47 years, with chronic low back pain. The measurements comprised cross-sectional area (cm2) and density (Hounsfield units [HU]) of the paraspinal muscles at Th12-L1, L3-L4, and L4-L5. To measure the reliability of the equipment and the observer (total reliability), two independent CT scans were performed for each patient. The radiologist traced the cross-sectional area twice within 2 weeks for measurement of the intraobserver reliability.

RESULTS

There were no significant differences in the assessments between the first and second CT scans, or between the radiologist's two measurements of the identical slices. The critical difference for the total reliability ranged from 11.3 to 22.8 for the density and from 10.0 to 16.0 for the cross-sectional area. For the cross-sectional area, the measurement error associated with the observer was higher than for the equipment. For the density, the measurement error related to the equipment was higher. The main measurement error was associated with the radiologist for the cross-sectional area and with the CT scanner for the density.

CONCLUSIONS

The reliability of the CT scan for measuring the cross-sectional area and density of the back muscles is acceptable. The authors do not know definitely whether their results can be generalized because the interobserver and intermachine reliabilities were not investigated.

Myotonometer intra- and interrater reliabilities

OBJECTIVES

To assess the intra- and interrater reliabilities of the Myotonometer, a hand-held, computerized, electronic device that quantifies muscle stiffness (tone/compliance).

DESIGN

Reliability study.

SETTING

Research laboratory.

PARTICIPANTS

Thirty-five healthy, nondisabled adults (age range, 22-42 y).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Two raters used the Myotonometer to evaluate subjects' lateral gastrocnemius and biceps brachii muscles. Muscles were measured in a relaxed state and during a voluntary isometric contraction. Coefficients were calculated for each muscle and each condition (relaxed, contracted). Results were analyzed by using Design II intraclass correlation coefficients.

RESULTS

Reliability coefficients were highest when the instrument exerted moderate to strong forces against the muscle (range, 0.50-2.00 kg; intrarater reliability R range, .84 - .99; interrater reliability R range, .75 - .96).

CONCLUSIONS

Myotonometer measurements had high to very high intra- and interrater reliabilities for measurements of the lateral gastrocnemius and biceps brachii muscles.

Intra-tester reproducibility of pressure biofeedback in measurement of transversus abdominis function

BACKGROUND AND PURPOSE

Strength, co-ordination and timing of transversus abdominis muscle contraction may be important in stabilizing the low back, and contraction of this particular abdominal muscle may be one factor capable of preventing and reducing low back pain in sport and in activities of daily living. The function and strength of the transversus abdominis muscle is difficult to measure. The pressure biofeedback unit (PBU) is a device designed to teach and measure transversus abdominis muscle function. The purpose of the present study was to evaluate intra-tester reproducibility of the PBU.

METHOD

The study used a test-retest design. Fifteen healthy subjects (mean age 22.2 years, range 19-28 years) with no history of low back pain participated in the study. After two sessions of practising transversus abdominis muscle contraction, its function was measured in prone position with the PBU device placed over the transversus abdominis muscle. Subjects were instructed to draw in the abdominal wall (for example, lifting it away from the device) after a standardized procedure. Two tests were conducted on two different days, with a seven-day interval in between.

RESULTS

Coefficient of variance (CV) was 21.0% and the standard deviation (SD) of delta was 1.59.

CONCLUSION

The use of the PBU should be improved for scientific purposes. However, the device may have a role in providing biofeedback to assist in the instruction of correct transversus abdominis muscle contraction.

Assessment of isokinetic muscle strength in women who are obese

STUDY DESIGN

Cross-sectional study of isokinetic trunk and knee muscle strength in women who are obese.

OBJECTIVE

To provide reference values, to identify variables that affect peripheral muscle strength, and to provide recommendations for isokinetic testing of trunk and knee muscles in women who are obese and morbidly obese.

BACKGROUND

The assessment of peripheral muscle strength is useful for the quantification of possible loss of strength, for exercise prescription, and for the evaluation of the effect of training programs in obese individuals.

METHODS AND MEASURES

Isokinetic trunk and leg muscle strength was assessed in 241 women who were obese (18-65 years, body mass index (BMI) > or = 30 kg/m2). Trunk flexion and extension peak torque (PT) was measured using the Cybex TEF dynamometer; trunk rotation (TR) PT was measured using the Cybex TORSO dynamometer; and knee flexion/extension (KFE) PT was measured using the Cybex 350 dynamometer. Body composition was assessed using the bioelectrical impedance method; physical activity was assessed using the Baecke questionnaire; and peak VO2 was assessed using an incremental exercise capacity test on a bicycle ergometer. To identify variables related to muscle strength, Pearson correlations were computed and a stepwise multiple regression analysis was performed.

RESULTS

Pearson correlation coefficients of all strength measurements at 60 degrees/s revealed low-to-moderate negative associations with age and positive associations with mass, height, fat free mass (FFM), and peak VO2 (P < 0.05), except for gravity-uncorrected trunk extension strength, which was not related to mass. The sports index of the Baecke questionnaire was associated with TR PT (r = 0.20, P < 0.01) and KFE PT (r = 0.18, P < 0.05).

CONCLUSION

The weight of the trunk accounts largely for the measured trunk extensor and flexor strength in women who are obese. Contributing variables of isokinetic trunk flexion and extension strength in women who are obese are age, height, and FFM; whereas sports activities and aerobic fitness are contributing factors for trunk rotational and knee extension strength. Recommendations for measuring isokinetic muscle strength in individuals who are obese are provided.

Measures of low back function: a review of reproducibility studies

OBJECTIVE

The objective of the present study was to make a systematic literature review with preset quality criteria concerning reproducibility of the tests of the low back regarding strength, endurance and range of motion.

DESIGN

Literature in Medline and local databases was reviewed for articles concerning the reproducibility of strength, endurance, and range of motion measurements.

BACKGROUND

Measures of low back function are widely used, and are important for both clinical and research purposes in relation to low back problems. A review of the reproducibility of these tests has not previously been made.

METHODS

After extensive discussion among all the authors, general evaluation parameters were defined for the quality assessment. Every study was graded from 0 to 2 for each parameter. Parameters evaluated were: number of subjects, subject description, method description, test/retest interval, description of results, and statistics.

RESULTS

The literature search revealed a total of 79 studies. Most studies suffered from methodological weaknesses and only eleven studies received ten or more quality points (maximum 14). The results from the highest graded studies are highlighted.

CONCLUSIONS

It may be concluded that there is a considerable lack of information about the reproducibility of functional measures for the low back, and therefore a recommendation for consensus is difficult. However, most tests performed in the sagittal plane are reliable for use on groups.

RELEVANCE

Measures of low back function are thought to be of great importance for clinicians, and low back researchers in general. A review of reproducibility will be helpful both as a survey of tests, and to provide information on the usefulness in relation to the level of reproducibility.

Study of differences in peripheral muscle strength of lean versus obese women: an allometric approach

OBJECTIVE

To investigate whether peripheral muscle strength is significantly different between lean and obese women controlled for age and physical activity, using an allometric approach.

DESIGN

Cross-sectional study of isometric handgrip and isokinetic leg and trunk muscle strength.

SUBJECTS

173 obese (age 39.9+/-11.4 y, body mass index (BMI) 37.8+/-5.3 kg/m(2)) and 80 lean (age 39.7+/-12.2 y, BMI 22.0+/-2.2 kg/m(2)) women.

MEASUREMENTS

Anthropometric measures (weight, height) and body composition (bioelectrical impedance method), isometric handgrip (maximal voluntary contraction on the Jamar dynamometer), isokinetic trunk flexion-extension, trunk rotation, and knee flexion-extension (Cybex dynamometers).

RESULTS

Absolute isokinetic strength output (that is, strength uncorrected for fat-free mass) was larger in obese compared to lean women, except for knee flexion and isometric handgrip, which were not significantly different (P>0.05). Pearson correlation coefficients between strength measures and fat-free mass (kg) were low to moderate both in lean (r=0.28-0.53, P<0.05) and in obese (r=0.29-0.49, P<0.001) women. There was no correlation with fat mass (kg) in the lean, whereas in the obese women a weak positive relation could be observed for most isokinetic data (r=0.21-0.39, P<0.01). When correcting for fat-free mass (raised to the optimal exponent determined by allometric scaling), all strength measurements were at least 6% lower in obese when compared to the lean women, except for trunk flexion, which was at least 8% stronger in obese women.

DISCUSSION

The higher absolute knee extension strength measures of leg and the similar extension strength of the trunk in the obese sample compared to the lean might be explained by the training effect of weight bearing and support of a larger body mass. However when the independent effect of fat-free mass is removed, these strength measures, as well as oblique abdominal muscle and handgrip strength, turned out to be lower in obese women. These observations could be the reflection of the overall impairment of physical fitness as a consequence of obesity and its metabolic complications.

Reliability of the isokinetic trunk extensor test, Biering-Sørensen test, and Astrand bicycle test: assessment of intraclass correlation coefficient and critical difference in patients with chronic low back pain and healthy individuals

STUDY DESIGN

A reliability study was performed.

OBJECTIVE

To determine the intersession reproducibility of the isokinetic trunk extensor strength test, the Biering-Sørensen test, and the Astrand test by calculation of the intraclass correlation coefficient and the critical difference.

SUMMARY OF BACKGROUND DATA

Several physical measurements have been used in clinical evaluation of patients with chronic low back pain. Reliability can be evaluated by calculation of either intraclass correlation coefficient or critical difference, but interpretation of the results may vary depending on which method is used.

METHODS

For this study, 31 patients with chronic low back pain carried out the isokinetic trunk extensor test, the Biering-Sørensen test, and the Astrand test as also did age- and gender-matched healthy individuals. Measurements were performed in three separate sessions at the same time of the day and by the same experienced examiner. The intervals between the sessions were 5 to 10 days.

RESULTS

The isokinetic tests showed a learning effect between Tests 1 and 2. For the isokinetic test, the critical difference increased with increased angular velocities from 28% to 63% in the patients and from 27% to 39% in the healthy subjects. The critical differences for the patients and the healthy individuals were 57% vs 54% for the Biering-Sørensen test and 21% vs 23% for the Astrand test, respectively. The intraclass correlation coefficient ranged from 93% to 98% in the patients and 80%-98% in the healthy individuals.

CONCLUSIONS

The reliability was found to be acceptable for the Astrand test and the isokinetic test at 60 degrees per second, as evaluated by the critical difference. All the tests were highly reliable according to the intraclass correlation coefficient, except for Biering-Sørensen test for healthy individuals. The critical difference is the preferable measure because calculation of the intraclass correlation coefficient may give a misleading high estimate of reliability.

Minimal influence of facet joint anesthesia on isokinetic muscle performance in patients with chronic degenerative low back disorders

STUDY DESIGN

Experimental design.

OBJECTIVES

To examine the influence of pain reduction after facet joint injections on isokinetic back muscle performance.

SUMMARY OF BACKGROUND DATA

Methods for evaluating the effect of facet joint injections vary. Recent studies base their results solely on the patient's subjective opinion and suggest a need for more objective, concrete, and reliable measurements.

METHODS

Eighty-seven patients with a degenerative low back disorder (49 women and 38 men; mean age, 48 years; range, 22-79) who had facet joint injections as a part of preoperative evaluation participated. The mean duration of symptoms was 12.3 years (range, 1-45). The patients underwent isokinetic trunk flexor and extensor muscle strength testing at angular velocities of 60 deg/sec and 120 deg/sec. They performed two tests before the facet joint injections (to eliminate learning effect). All patients had bilateral facet joint injections at L5-S1. Those who did not report pain relief had additional injections at L4-L5. The flexion-extension test was repeated 15 minutes after each injection. Pain and fear were registered on visual analog scales.

RESULTS

All 87 patients could perform the isokinetic tests. For extension at 60 deg/sec, a significant improvement was found between the two pretests (P < 0.05). Pain increased significantly from the first to the second pretest (P = 0.02), and a significant decrease in pain was found after the first injection (P = 0.0001). Fear decreased between each test, with a significant decrease after the first injection. No significant change was found for the muscle strength measurements after facet joint anesthesia. There were only weak correlations between decrease in pain and alteration in muscle performance, ranging from 0.06 to 0.37.

CONCLUSION

Pain reduction after facet joint injections did not influence isokinetic muscle performance in patients with degenerative low back disorders.

Do functional tests predict low back pain?

STUDY DESIGN

A cohort of 307 nonsymptomatic workers and another cohort of 123 workers with previous episodes of low back pain were followed up for 2 years. The outcomes were measured by symptoms, medical consultations, and sick leaves due to low back disorders.

OBJECTIVES

To study the predictive value of a set of tests measuring the physical performance of the back in a working population. The hypothesis was that subjects with poor functional capacity are liable to back disorders.

SUMMARY OF BACKGROUND DATA

Reduced functional performance has been associated with back pain. There are few data to show whether reduced functional capacity is a cause or a consequence of pain.

METHODS

Mobility of the trunk in forward and side bending, maximal isokinetic trunk extension, flexion and lifting strength, and static endurance of back extension were measured. Standing balance and foot reaction time were recorded with a force plate. Clinical tests for the provocation of back or leg pain were performed. Gender, workload, age, and anthropometrics were managed as potential confounders in the analysis.

RESULTS

Marked overlapping was seen in the measures of the subjects with different outcomes. Among the nonsymptomatic subjects, low performance in tests of mobility and standing balance was associated with future back disorders. Among workers with previous episodes of back pain, low isokinetic extension strength, poor standing balance, and positive clinical signs predicted future pain.

CONCLUSIONS

Some associations were found between the functional tests and future low back pain. The wide variation in the results questions the value of the tests in health examinations (e.g., in screening or surveillance of low back disorders).

Inertial effects on moment development during isokinetic concentric knee extension testing

STUDY DESIGN

Two group pre-test post-test design was used with 2 isokinetic dynamometers in a laboratory setting.

OBJECTIVES

To evaluate the inertial effects on moment measurements during the initial acceleration period of concentric isokinetic knee extension.

BACKGROUND

Torque acceleration energy is a controversial measure of muscle "explosive power." Moments due to acceleration during the initial period of isokinetic movements have been ignored in the majority of isokinetic studies.

METHODS AND MEASURES

These inertial effects were assessed at various angular velocities measuring the work production at the initial 0.125 second on a Biodex and a Lido dynamometer. Four women (age, 23.33 +/- 2.49 years) and 5 men (age, 26.00 +/- 2.63 years) were tested on Biodex. A different group of 9 men (age, 23.4 +/- 3.41 years, height, 1.77 +/- 1.02 meters, and mass, 74 +/- 8.26 kg) was tested on the Lido. Joint moment was calculated by including moments associated with the angular acceleration of the lower limb and the lever arm.

RESULTS

Torque acceleration energy was significantly greater after correction for inertial effects compared with uncorrected measures at moderate (165 and 180 deg/s) and high velocities (300 deg/s) on both dynamometers.

CONCLUSION

In cases where moment development in the initial 0.125 second of an isokinetic movement is measured, it would be better to use slow velocities where inertial effects are minimum. At high angular velocities inertial correction is essential to acquire valid moment measurements and conclusions about muscle and joint function.