Jennifer L Keating

Do within-session changes in pain intensity and range of motion predict between-session changes in patients with low back pain?

Physiotherapists commonly use post-treatment changes in a patients pain intensity and range of motion to guide treatment selection and predict possible longer-term outcomes. This study tested the validity of this practice by evaluating the predictive value of within-session changes in pain intensity and range of motion in 53 patients with low back pain. Pain intensity and range of motion measurements of spinal flexion, extension, lateral flexion, and straight-leg-raise were taken by the patients therapist before and after one treatment session, and were repeated by a blinded therapist at the beginning of the patients subsequent treatment session. Regression analysis revealed that the strength of association between within-session and between-session changes ranged from r = 0.35 to r = 0.80 for range of motion measurements, and from r = 0.24 to r = 0.47 for pain intensity. Odds ratios for pain and range of motion ranged from 3.5 (95% CI 0.9 to 14.6) to 37.0 (95% CI 4.1 to 330), indicating greater odds of improving between-session if improvement was obtained within-session. These results provide preliminary support for the practice of using within-session changes in pain intensity and range of motion to guide treatment selection when treating impairments in patients with low back pain.

Reproducibility and validity of a new test protocol for measuring isokinetic trunk extension strength.

OBJECTIVEnTo investigate the reproducibility and validity of isokinetic trunk extension strength scores obtained using a range of motion of 20 degrees and velocities of 10 and 40 degrees /s.nnnBACKGROUNDnCommon protocols for testing trunk extension strength incorporate a range of motion of 40 degrees or more and test velocities of between 30 and 180 degrees/s. These test parameters may be neither necessary for portraying the strength profile of the muscles involved nor suitable for patients impaired with low back dysfunction.nnnDESIGNnTest-retest of maximal concentric and eccentric isokinetic trunk extension strength in healthy subjects.nnnMETHODSn17 women and 18 men were tested twice within 1-2 weeks. Tests were performed with subjects positioned in sitting.nnnRESULTSnThe trunk extension strength scores revealed excellent agreement with the expected physiological moment-velocity curve. On average womens trunk extension strength was 62% that of men (range: 59.3-64.4%). The test-retest correlation coefficients were generally higher in women (0.70-0.87) than in men (0.52-0.78) and significant at P=0.01. The standard error of measurement ranged between 13 and 21 N m for women and between 35 and 50 N m for men, which were equivalent to 9% and 15% of the mean strength in women and men, respectively.nnnCONCLUSIONnThis study indicates that the present protocol may be validly applied in assessing trunk extension strength in normal women.nnnRELEVANCEnReproducible and valid trunk extension strength findings are essential if measurable strength deficiency of the extensors is to be formally accepted as an impairment. The present protocol incorporates or meets most of the relevant problems associated with trunk concentric and eccentric strength testing, and hence has the potential of becoming a standard method for clinical applications.

Trunk extension effort in patients with chronic low back dysfunction.

Study Design. Single-session measurement was performed. Objective. To measure trunk extension strength and assess trunk extension effort in patients with chronic low back dysfunction using a novel test protocol and the DEC parameter. Summary of Background Data. In normal subjects, the DEC parameter effectively and reproducibly differentiates between maximal effort and feigned weakness of the trunk extensors, but its applicability to patients with chronic low back dysfunction has not yet been explored. Methods. Isokinetic trunk extension strength was measured in 44 patients with chronic low back dysfunction (22 women and 22 men) who were not involved in litigation process. Tests were conducted using a range of motion of 20°, angular velocities of 10° and 40° per second, and an isometric preactivation force of 50 N. The average strength at these velocities served for calculation of the DEC score, which is the difference between the eccentric and concentric strength ratios at these velocities. Results. The strength scores resembled the characteristic physiologic moment–angular velocity relation, and were much reduced, as compared with the scores of normal subjects. The DEC scores for 39 patients (89%) were less than the cutoff value, which in normal subjects differentiates maximal effort (below cutoff) from feigned weakness (above cutoff) at tolerance limits of 99%. This figure was slightly lower (84%) at a corresponding 95% level. A principal finding in the false-positive cases was a particularly low concentric strength at 40° per second. Conclusions. This study indicates that under the current protocol, the large majority of patients perform at a maximal level of effort.

Identifying feigned isokinetic trunk extension effort in normal subjects: an efficiency study of the DEC.

Study Design. A test–retest comparison of maximal and feigned trunk extension effort in normal subjects was performed. Objective. To test the robustness of an index termed DEC for differentiating maximal from feigned effort in normal subjects. Summary of Background Data. Previous studies have indicated that the DEC, which is the difference between the eccentric to concentric strength ratio at two test velocities, is a powerful identifier of feigned effort. This has been found for various muscle groups including the trunk extensors. However, whether this efficiency is affected by exposure to the protocol, learning, or other factors had not been examined. Methods. Using a KinCom isokinetic dynamometer, 18 men and 17 women were tested twice within 1 to 2 weeks. Concentric and eccentric efforts of the trunk extensors were exerted using a short range of motion (20°) and two test velocities (10° and 40° per second). In the first part of each test, participants exerted maximal force against the lever arm, whereas in the second part they were to feign their maximal capability, pretending the presence of injury. Results. In both Tests I and II, the feigned DEC scores (DECf) of all the participants were greater than the maximal DEC (DECm) scores (P = 0.0001). Repeated measurement analysis showed that neither DECm nor DECf varied systematically from Test 1 to Test 2. On the basis of the individual male scores, the DEC cutoff score of 0.41 was 100% efficient in Test 1 at differentiating feigned from maximal effort, with neither false-positive nor false-negative cases. Test 2 had a single false-positive case (efficiency 95%), and the optimal cutoff score was 0.275. In the female group, the corresponding efficiency of the DEC was 82% (optimal cutoff, 0.35) for Test 1 and 70% (optimal cutoff, 0.25–0.35) for Test 2. A statistical model for tolerance intervals at 90%, 95% and 99% indicated higher cutoff values for women than men. Conclusion. In healthy subjects, the DEC effectively differentiates feigned from maximal performance.

Injury in the Australian sport of calisthenics: A prospective study

The aims of this study were to determine the rate, anatomical regions, onset, severity, and type of injury in the sport of calisthenics and compare injuries reported by elite and non-elite participants. Prospective reports of injuries were collected over a 12-month period from 550 elite and non-elite calisthenics participants. The participants recorded the number of training sessions, competition, and performances per week, hours of training, and information on any injuries sustained each week during the survey period. Five hundred and fifty participants reported 190 injuries during the survey period, 0.4 injuries per participant year or 0.3 injured participants per participant year. The odds ratio of injury in the elite to the non-elite group was 2.0 (95% CI 1.3 to 2.9). Injuries to the lower back (32.4% of all injuries), hip thigh and groin (25.4% of all injuries) were most common. Activities involving lumbar extension (29.8% of all injuries and 61.0% of lower back injuries) were perceived by participants to have led to injury. In general, injuries were minor and mainly involved soft tissue structures (95.6% of all injuries). Participants had difficulty in identifying why their injuries had occurred. Calisthenics participants did not report high injury rates, but activities that involve lumbar extension are implicated in low back injuries and warrant further attention

Measurements of ankle dorsiflexion in stroke subjects obtained using standardised dorsiflexion force

This study investigated the reliability of measurements of ankle dorsiflexion obtained using the Lidcombe Template, an instrument that allows the magnitude and direction of force applied to dorsiflex the foot to be measured and standardised. Ten unimpaired physiotherapy students and 21 subjects who had suffered stroke were tested twice. Twenty minutes separated tests. Measurements of passive dorsiflexion range were highly reliable for both groups (r > 0.92) when the mean of three measurements was used. Significantly more variability occurred in measurements of impaired subjects than unimpaired subjects. For the subjects tested, for 95 per cent confidence that real differences exist between measurements taken 20 minutes apart, 7 degrees and 3 degrees must be allowed around measurements of impaired and unimpaired subjects respectively. These small error margins confer confidence in the potential utility of this instrument for measuring ankle dorsiflexion.

The effect of preload on variability in dynamometric measurements of knee extension

Abstract. The unwanted variability in dynamometric measurements limits accurate interpretation of these measurements. Although unpredictable variability in measurements has been identified repeatedly, few studies have investigated strategies for reducing measurement error. This study investigated the effect of preload on variability in dynamometry. Preload is the force that must be overcome before the lever arm begins to move at a preset speed. On the basis of related research, it was hypothesised that under higher preloads, subjects would perform more consistently. Twenty subjects (ten male and ten female), aged 19–24xa0years, performed repeated right concentric knee extension tests. Using the Kin-Com dynamometer and a lever arm speed of 60°·s–1, extension torques were recorded for each subject under four different preload conditions. Preloads were 5%, 25%, 45% and 65% of the torque achieved during each subjects maximal voluntary contraction (MVC). Each subject performed six test repetitions under each preload. Variability in peak torque was significantly smaller under the 65% preload compared to the 5% preload. In addition, the regression of preload against group mean variability indicated that as preload increased, the variability in peak torque decreased in a highly predictable way. The results from this study suggest that subjects perform more consistently under conditions of higher preload than under lower preloads. By adopting higher preloads for dynamometry testing, measurement accuracy and the potential clinical utility of measurements is improved.