Baltimore Therapeutic Equipment Research Articles

Validity of the Baltimore Therapeutic Equipment Work Simulator in the Measurement of Lifting Endurance in Healthy Men

To examine the criterion validity of the Baltimore Therapeutic Equipment (BTE) work simulator by comparing endurance time, oxygen uptake (VO2), and heart rate measured during real and simulated lifting tasks and to derive a regression equation for predicting actual lifting endurance from measurements on the work simulator. Twenty healthy male volunteers repetitively lifted and lowered a load of 40 lb using the BTE work simulator and actual weights at a laboratory workstation. Postures, location, and frequency of lifts were kept constant. Endurance (defined as the time taken for the rating of perceived exertion to increase 2 units on the Borg scale) was measured under both conditions. VO2 and heart rate were also recorded, using standard physiological procedures. The mean values for endurance time, steady-state VO2, and heart rate were significantly different between the real and simulated tasks (p < .05). Correlation of endurance time between the two tasks was significant (r = .71, p < .05). Step wise regression analysis resulted in the following equation for predicting real endurance from simulated time measurements: predicted real time = .34 simulated time + 3.29; r = .71; SE = 1.00 min. The BTE work simulator tends to overestimate real lifting endurance performance in healthy men. The lower physiological stress during the simulated task suggests a significant difference between the real and simulated loads. Occupational therapists should exercise caution when using the results of the BTE work simulator during functional capacity evaluations.

Consistency of performance on the functional capacity assessment: static strength and dynamic endurance.

To explore the degree of consistency in a subject's performance in physical strength and endurance. Thirty healthy men, aged 19 to 26 yr, were recruited to participate in protocols to assess static strength and dynamic endurance tests on their upper limbs with the Baltimore Therapeutic Equipment Primus. Retests were conducted 7 days after the initial test. The intraclass correlation coefficients were 0.71 to 0.97 and 0.32 to 0.90 for static and dynamic endurance strengths, respectively. These results indicated that the consistency of the subjects' performance across occasions was high for testing static strength, although it was more varied for testing endurance strength. Higher consistency was observed among subjects in the assessment of static strength than dynamic endurance strength. The range of motion traveled by the limb, speed of performance, and ergonomic design of attachments seemed to confound the subjects' performance on the instrument. Stringent assessment protocols, ergonomically designed hardware, and clear instructions and practice trials before the formal testing were essential to maximize the subjects' consistency of performance. The results of this study were applicable and generalized to other performance-based instruments for physical and functional capacity evaluation and work simulators.

Work profile and functional capacity of formwork carpenters at construction sites

Purpose :This study established a work profile and functional capacity for formwork carpenters (FCs) working at construction sites. Method : Thirty male FCs aged 19-45 were recruited by convenient sampling from the construction training centres. All FCs participated in an interview/questionnaire and a standardized functional capacity evaluation (FCE) using the Baltimore Therapeutic Equipment Primus (BTE Primus) and Valpar Component Work Sample (VALPAR19). Thirty male adults (office workers) aged 19-45 participated in the exact FCE for comparison. Results : The results of the questionnaire indicated that the job demands of formwork carpenters were frequent lifting (46.7%), carrying (50.0%) and handling (60.0%). Significantly higher lifting and carrying capacities were revealed among the FCs, but not in their isometric strengths and the endurance of the upper limbs ( x 2 = 6.48, df = 2, p < 0.05). Conclusions : The dynamic and repetitive sub-maximal nature of the work of formwork carpentry induced an elevation of jobspecific lifting and carrying capacities among the FCs. The job and functional capacity profiles would be useful for formulating guidelines for the rehabilitation of injured workers and the training of new workers in the trade.

Reliability of the Manual Dynamic Mode of the Baltimore Therapeutic Equipment Work Simulator

Twelve Baltimore Therapeutic Equipment Work Simulators (BTEWS) were tested for consistency of resistance in the manual dynamic mode using a previously described timed weight-drop test. Fifty weight-drop measurements were made at five different weight levels: 5, 10, 20, 30, and 40 lb. Alterations in weight-drop times indicate changes in exercise-head resistance. Substantial resistance variation was found in the manual dynamic mode. With console resistance set consistently at 92% of applied weight, weight-drop times varied from failures of the weight to drop to times that were not recognized by the electronic timing system. Measurable weight-drop times ranged from 0.75 to 16.97 seconds. Ten Simulators had weight-drop times greater than +/-3 standard deviations (SD) from the mean; eight Simulators had times +/-4 SD from the mean; and four had times +/-5 SD from the mean. Console printout data did not accurately reflect resistance produced by the exercise head. While intermachine correlations based on Simulator printout data ranged from +1.0 to +0.9906, correlations derived from resistance-based weight-drop times ranged from +0.9866 to -0.9956. For a constant externally applied torque, the weight-drop times should have been constant but were not. Resistance produced in the manual dynamic mode is inconsistent, both within and between machines (p = 0.0001).

Functional evaluation of the shoulder following latissimus dorsi muscle transfer.

The dynamic muscle function of the shoulder in 26 patients (10 males, 16 females) who underwent a pedicled or free vascularized latissimus dorsi muscle transfer between 1985 and 1991 (mean follow-up, 4.4 yr) was studied. Instrumented muscle testing was performed on the Kinetic Communicator machine (Kin Com) and the Baltimore Therapeutic Equipment (BTE) work simulator. The female unilateral pedicle group (n = 13) showed a significant difference between operated and nonoperated shoulders for both peak torque (power) and work (endurance) measurements of shoulder adduction and extension on the Kin Com (mean ratios operated/nonoperated shoulders, 55% to 69%). They also showed significant differences for work performance on three of four BTE tests (mean ratios, 77% to 84%). The male free vascularized group (n = 10) similarly showed a significant deficit of both peak torque and work for shoulder extension and adduction on the Kin Com (mean ratios, 74% to 84%); however, they showed no deficit on the BTE tests. In conclusion, dynamic muscle tests demonstrate a deficit of muscle power and endurance of shoulder extension and adduction following latissimus dorsi muscle transfer.

Steindler and pectoralis major flexorplasty: A comparative analysis

Previously published studies on transfers to restore elbow flexion have rarely compared the outcomes among different techniques. We found no comparison between the Steindler procedure and pectoralis major tendon transfer. This study compared functional outcomes after these two types of elbow flexorplasty performed in conjunction with shoulder arthrodesis for patients with brachial plexus injuries. The same examiner assessed 14 patients who underwent shoulder fusion and elbow flexorplasty. Five had a pectoralis major tendon transfer, and nine underwent a modified Steindler procedure. All patients had brachial plexus lesions that were irreparable or had not responded to neurolysis, repair, or grafting. Average follow-up time was 60 months (range, 12 months-10 years). All patients completed a questionnaire (pain, function) and underwent an objective assessment of range of motion, isometric strength, isotonic power, grip, and pinch strength. The BTE Work Simulator (Baltimore Therapeutic Equipment, Hanover, MD) was used for muscle strength testing. Improvement was noted in daily activities including dressing and bilateral activities and was reflected in a significant improvement over preoperative function. No differences (at p = .05 level of significance) were found in objective tests between the pectoralis major transfer and the Steindler groups. In the patient requiring stabilization of the shoulder and flexorplasty, the pectoralis major tendon transfer was at least equivalent to the modified Steindler flexorplasty in terms of range of motion, strength, and subjective measures.

Gender Differences in Work Performance on the Baltimore Therapeutic Equipment Work Simulator

The purposes of this study were to (a) establish biomechanical and physiological normative data for healthy young women performing three tasks on the Baltimore Therapeutic Equipment work simulator (BTE): wheel-turn, push-pull, and overhead-reach; and (b) compare these data with previously reported values for healthy men of a similar age group. Twenty women completed five test sessions: (a) task familiarization on the BTE to determine the work intensity that was perceived as hard on the Borg scale, (b) incremental test on an arm crank ergometer to measure peak oxygen uptake (VO2) and peak heart rate (HR), and (c) one of the three tasks in random order for 4 min during the next three sessions. Physiological responses were monitored with a metabolic cart interfaced with an electrocardiogram. Torque, work, and power during the three tasks were significantly higher (p < .05) in men than in women. The absolute VO2 (L.min-1) during these tasks was higher in men, but when the VO2 was calculated relative to body weight (ml.kg-1.min-1), no significant (p > .05) gender differences were observed. Computation of energy expenditure relative to body weight and power output (cal.kg-1.W-1) indicated that women expended significantly (p < .05) more energy than men. No significant (p > .05) gender differences were observed for VO2 and HR when the values were expressed as a percentage of their respective peaks. Findings indicated that (a) the functional work capacity is significantly lower in women than in men, (b) women are less efficient than men when the energy expenditure is expressed per unit of body weight and power output, and (c) the relative physiological stress in men and women is similar under these conditions.

The Baltimore Therapeutic Equipment work simulator: biomechanical and physiological norms for three attachments in healthy men.

The Baltimore Therapeutic Equipment (BTE) work simulator is routinely used by occupational therapists in functional capacity evaluation. Currently, there is a lack of normative data for various attachments on this instrument. The purposes of this study were to (a) establish norms for the biomechanical and physiological responses during three tasks on the BTE work simulator, namely, wheel-turn, push-pull, and overhead-reach; (b) compare these responses during the three tasks, and (c) examine the interrelationships of these responses during the tasks. Twenty healthy men completed five testing sessions: (a) task familiarization on the BTE work simulator to identify the work intensity, which was perceived as hard on the Borg scale; (b) an incremental arm ergometer exercise test to determine their peak oxygen uptake (pVO2) and peak heart rate (pHR); and (c) one of the three tasks on the BTE work simulator for 4 min in each of the next three sessions. Analysis of variance indicated that torque, work, and power during the overhead-reach were significantly higher (p = .000) compared with the wheel-turn and push-pull tasks. However, no significant differences (p > .05) were observed among the tasks for the VO2 and HR, which were approximately 50% and 70% of pVO2 and pHR respectively. Although there was a significant relationship (p < .05) among tasks for the torque, work, and power, the common variance ranged only between 38% and 67%. The relative pVO2 was significantly related to work (p = .028) and power (p = .027) only during the push-pull task but not the wheel-turn and overhead-reach tasks. These results suggest that occupational therapists should include as many tasks as possible when designing functional capacity evaluation test batteries, and that there is no consistent relationship between cardiorespiratory fitness and performance of various tasks on the BTE work simulator.

The Baltimore Therapeutic Equipment Work Simulator: reliability and validity at three work intensities.

To determine test-retest reliability and criterion validity of the Baltimore Therapeutic Equipment Work Simulator (BTE), 30 male volunteers, 18 to 30 years, performed three criterion tasks at light (CL), medium (CM), and heavy (CH) levels of intensity and three corresponding simulated tasks (SL, SM, SH), all of which were repeated on a subsequent session. Oxygen consumption (VO2) and heart rate (HR) were monitored continuously during these tasks. Correlation coefficients between trials of the same task for VO2 (r = .74-.87) and HR (r = .58-.78) indicated significant test-retest reliability. Although criterion-simulation correlation coefficients were significant, consistently high criterion validity was found only at CL-SL (VO2, r = .81 and .83; HR, r = .88 and .95). The nature of the task may have influenced CM-SM correlations. It also appears that subjects underestimated the amount of resistance required on the BTE to simulate CH. Caution is urged in making judgments about a subject's abilities to do real work at medium and heavy intensities based only on test results from the BTE.

Computer Analysis of the Performance of the BTE Work Simulator

The BTE Work Simulator (Baltimore, Therapeutic Equipment Co., Hanover, Md.) recreates the work environment by providing a rotatable shaft to which a variety of tools can be attached. The patient can simulate the coordinated muscle and joint movements involved in the work situation, exercising either isometrically or isotonically, and thereby increase the potential for return to work. The BTE Work Simulator has four major components: the exercise head to provide variable resistance, tools that attach to the exercise head, a control console containing a microprocessor that calculates work and power, and the Quest software package (Baltimore Therapeutic Equipment Co.). Quest provides four static/isometric and seven dynamic/isotonic tests that can be used to document the extent of a patient's impairment. In addition, it has daily treatment options and acts as an extensive data base capable of retrieving any stored test or treatment results. This software system greatly facilitates the use of the BTE Work Simulator by providing instant calculations of power and coefficients of variation, immediate patient feedback, graphic expansion of the data, and printed evaluation reports.

Test-Retest Reliability and Day-to-Day Variability of an Isometric Grip Strength Test Using the Work Simulator

The test-retest reliability and the day-to-day variability of an isometric grip strength test using the power grip attachment of the Baltimore Therapeutic Equipment Work Simulator were investigated for three methods of determining a criterion score. These methods were the mean of three trials, the mean of the best two of three trials, and the best score of three trials. Subjects included 30 right-dominant males and females, 20 to 45 years old. The method with the highest test-retest reliability and the lowest day-to-day variability was the mean of three trials. The reliability coefficients were .978 for the right hand and .987 for the left hand. The day-to-day variability was 4.99% for the right hand and 3.04% for the left hand. Based on the results of this study, it is recommended that the mean of three trials should be used to determine the criterion score when evaluating isometric grip strength with the work simulator.

The Effect of the Duration of Intertrial Rest Periods on Isometric Grip Strength Performance in Young Adults

This study examined the effect of the duration of intertrial rest periods on isometric grip strength scores in successive trials with the use of the power grip attachment of the Baltimore Therapeutic Equipment work simulator. Male and female subjects, 19 to 41 years of age, were randomly assigned to one of three groups, categorized by 15-, 30-, or 60-sec rest periods between five consecutive isometric grip tests. No significant differences were found between the groups in the pattern of decline in torque across trials. However, the group with the longest intertrial rest period had a significantly smaller percentage of decline in torque from the first to the last trial and the highest intraclass correlation coefficient between the five trials for both hands. In addition, the same group of subjects demonstrated significantly smaller differences in torque from the first to the second pretrial, which had a 2-min rest period, than from the first to the second experimental trial, which had shorter intertrial rest periods of 15, 30, or 60 sec.

The American Society of Hand Therapists

The American Society of Hand Therapists Eighth Annual Meeting was held at the MGM Grand Hotel, January 23-25, 1985. Abstracts of the papers presented are published below. The hand therapist in industry: How to establish your services. SUSAN EMERSON, O.T.R., presented a program that integrates hand therapy in industry. The goals of such a program can be clinically oriented to increase the referral base, to prepare workers for return to work, to prepare site visits, and to act as a liaison between the physician and industry. It can also be consultation oriented to provide personnel support, work station evaluation and design, exercise programs, and development of light duty stations. Marketing and follow-up were an essential part of this program. SARA WALKER, O.T.R., agreed that patient treatment and consultation are valuable because more information on jobs and job stresses is needed. She emphasized that therapists must be well trained and base their programs on research before serving as a consultant. Preemployment analysis must be non biased and follow legal guidelines. The mutilated hand: A new alternative. BARBARA GOODWIN, R.P.T., and WANDRA MILES, O.T.R., presented ideas for patient selection and for patient physical and psychologic preparation for the passive functional prosthesis fabricated by DR. JEAN PILLET. They also presented the results of a survey of 25 patients to correlate factors such as sex, age, occupation, and level of amputation with user satisfaction/dissatisfaction with the prosthesis. ROSLYN EVANS, O. T.R., suggested that expansion of the survey questionnaire to investigate what effect the prosthesis has on an earlier return to work of the patient would provide useful information for the clinician and for insurance companies. An EMG analysis of five muscles with the use of tool attachments of the BTE (Baltimore Therapeutic Equipment) work simulator. SCOTT MCPHEE, O. T. R., studied the participation of five muscles in the forearm and hand during use of three tools on the BTE work simulator at three levels of resistance with use of EMG recordings on normal SUbjects. He concluded that at different levels of resistance the muscles participated in a different pattern, especially at zero resistance. This method can be used to develop a chart of muscle use at different levels to assist the therapist in selecting the optimal tool and resistance for the therapeutic effect desired. He believed that the research supports the use of different tool attachments and assists therapists in documenting the effect of therapy. JUDY BELL, O.T.R., pointed out that skin resistance is critical in the use of surface EMG electrodes, and that forearm and wrist position must be controlled during such studies. She questioned if the abductor pollicis brevis is representative of thumb flexion and extension. String wrapping versus massage for reducing digital volume. KENNETH FLOWERS, L.P.T., studied the effect of four techniques for reducing digital edema of four digits in 14 patients with edema secondary to proximal injury. Forty-four trials were run, alternating techniques to each digit, and each technique was applied for 5 minutes. Massage, string wrapping, and two combinations of those techniques were used, and circumference was measured before and after treatment. The two combined techniques were found to be significantly more effective than either of the pure techniques. No significant difference was found between massage and string wrapping alone. DONNA REIST, O.T.R.lL., complimented the author on this study that supports a clinical hunch that combined treatment is more effective. She criticized the research design because no reliability or validity measures were demonstrated, and there was no demographic information on subjects or indication of the duration that edema was present. She suggested that comparisons to the other hand be included. The effect of thumb interphalangeal joint position on strength of key pinch. EILEEN APFEL, O.T.R., presented a study to determine if thumb interphalangeal (IP) joint position affects the outcome of lateral pinch strength tests. Results demonstrated that 29 of 30 normal male and female subjects spontaneously flex their thumbs during lateral pinch. When thumb IP flexion was used, the female subjects demonstrated an increased strength of 30% for the right upper extremity and 28% for the left upper extremity compared to measurements with the use of thumb IP extension. The men demonstrated an increased strength of 36% for the right upper extremity and 38% for the left upper extremity