Biomedical subjects

J F Kramer

Publications and source records attributed to J F Kramer.

At least 37 records · Page 2Linked to original sources

PubMed1994

Rowing performance and selected descriptive, field, and laboratory variables.

The purpose of this study was to determine the relationships among measures of rowing performance and selected descriptive, field, and laboratory variables. Rowing performance of 20 intercollegiate oarswomen was assessed using a 2,500-m time test on a Concept II rowing ergometer, the rower's competitive experience, and the coach's ranking of the rowers. The oarswomen also underwent standardized descriptive tests including anthropometric measurements, field tests including 90-s rowing ergometer distance and weight lifting tests, and laboratory tests including VO2max and isokinetic knee extensor strength tests. Rowing ergometer times were highly related to competitive experience (rho = -0.86; p < 0.01) and coach's ranking (rho = 0.87; p < 0.01). VO2max was the only other variable to produce correlations greater than 0.71 with rowing performance. Although most of the correlations observed in the present study were poor to modestly high, they do document and quantify relationships, and suggest that training and testing techniques should be modified to be more rowing specific and that their usefulness with respect to positive transfer and prediction should be examined.

Adult↗

PubMed1994

Effect of TENS on pain, medications, and pulmonary function following coronary artery bypass graft surgery.

The efficacy of transcutaneous electrical nerve stimulation (TENS) as an adjunct to narcotic medications for the management of postoperative pain was assessed in a prospective, randomized, controlled study of patients following coronary artery bypass graft (CABG) surgery with the right or left internal thoracic artery (ITA). Forty-five male patients (mean age, 57 +/- 6 years) were randomly assigned to (1) TENS, (2) placebo TENS, or (3) control treatments (n = 15 each), following extubation and during the 24- to 72-h postoperative period. Two-way analysis of variance tests indicated no significant differences among treatment groups for (1) pain with cough, (2) narcotic medication intake, (3) FVC, (4) FEV1, and (5) PEFR (p > 0.05). However, pain at rest reported by the TENS group was significantly lower than that reported by the control group (treatment main effect; p < 0.04), although no significant differences were observed between the TENS and placebo or between the placebo and control groups (p > 0.05). All six criterion measures were characterized by significant changes over time for the entire group (n = 45; time main effect; p < 0.01), as follows: pain and medication intake were similar on days 1 and 2, but were significantly less on day 3, and pulmonary functions were significantly lower than preoperatively on day 1, decreased further on day 2, and despite an improvement on day 3, remained significantly lower than preoperative values (p < 0.01). This study suggests that the addition of TENS, applied continuously during the immediate postoperative period following CABG with ITA, may not be advantageous in pain management or the prevention of pulmonary dysfunction.

Analgesics, Opioid↗

PubMed1993

Changes in rowing ergometer, weight lifting, vertical jump and isokinetic performance in response to standard and standard plus plyometric training programs.

The purpose of this study was to compare standard (S-weight plus rowing ergometer training) and standard plus plyometric (S+P-weight plus rowing ergometer training, plus plyometric exercises) programs on sport-specific and non sport-specific tests. Twenty-four female rowers completed the weight training or the weight training plus plyometric exercises three times per week and rowing ergometer training four times per week, 1 hr per session for 9 wks. Analysis of variance tests were used to compare S (n = 11; 5 novice and 6 experienced rowers) and S+P (n = 13; 7 novice and 6 experienced rowers) programs on the following sport-specific tests: 1) time to row 2,500 m and 2) distance rowed in 90 s; and on the following non sport-specific tests: 1) leg press, 1 RM, 2) leg press endurance, 3) bench pull 1 RM, 4) bench pull endurance, 5) vertical jump, 6-9) isokinetic knee extensor peak and average power during concentric and eccentric muscle actions and 10) angle of occurrence of peak torque during concentric muscle actions (isokinetic knee extension). Although experienced oarswomen scored significantly higher than did novice oarswomen on eight of 12 tests (p < 0.04), both levels of rower responded similarly to training. No significant differences were observed post-training between the S and S+P training programs (p > 0.05). These results do not discount the value of plyometric exercises, but indicate that the jump exercises used offered no advantages to intercollegiate oarswomen.

Body Weight↗

PubMed1993

Effect of different TENS stimulus parameters on ulnar motor nerve conduction velocity.

The purpose of this study was to determine the effect of different TENS stimulus characteristics on ulnar motor nerve conduction velocity (MNCV) in the forearm and on forearm and ring finger skin temperatures. Thirty-one healthy women consented to receive conventional, acupuncture-like and placebo TENS: one treatment being randomly administered on each of 3 separate days within 1 week. No significant difference in MNCV (m/s) was observed between the three treatments at any of the six times of measurement (P > 0.05). Post-treatment MNCVs were, however, significantly slower than pretreatment velocities (time main effect; P < 0.01), although the differences were only about 3% in magnitude. No significant differences in finger or in forearm skin temperature were observed between the three treatments at any of the six times of measurement (P > 0.05). However, forearm skin temperatures were significantly higher than were ring finger skin temperatures, and only finger temperature changed over time (site x time interaction; P < 0.01). The small changes in MNCV and finger skin temperature were attributed to subject inactivity during testing. Acupuncture-like and conventional TENS do not have different or unique effects on motor nerve conduction velocity when applied at clinical levels of stimulus intensity.

Adult↗

PubMed1993

Isometric hip abductor strength following total hip replacement and its relationship to functional assessments.

Despite the rehabilitative emphasis on hip abductor strength following total hip replacement (THR), it is unclear how muscular strength is related to function. The purposes of this study were to examine changes in hip abductor strength during the first 6 months following THR and to determine the relationship between hip abductor strength and functional performances. Forty-three patients (mean age 64 +/- 7 years) completed strength assessments before surgery and at 1, 6, 12, and 24 weeks after surgery, and functional assessments before surgery and at 12 and 24 weeks after surgery. Both hip abductor strength and functional performance were significantly improved at each assessment (p < 0.01). The correlation between isometric hip abductor torques and the distance walked in 6 minutes was modestly high (r = 0.48-0.51; p < 0.01). This study provides baseline data for isometric hip abductor strength that can be used comparatively to assess patient progress and to help set clinical goals. Although strength is related to function, isometric measurements of strength should not be relied upon as the sole predictors of function in patients who have undergone THR.

Bone Cements↗

PubMed1993

Shoulder antagonistic strength ratios during concentric and eccentric muscle actions in the scapular plane.

Reporting agonist/antagonist ratios is frequently more clinically applicable than reporting absolute strength values of single muscle groups. The purpose of this study was to measure shoulder abduction/adduction and external/internal rotation ratios in the functional scapular plane of shoulder movement. Ratios were calculated using peak and average torques during concentric and eccentric muscle actions, and ratios of healthy males and females were compared. Thirty-six, non-athletic subjects performed concentric-eccentric cycles at two angular velocities. No significant differences were observed in the ratios using peak and average torques as criterion measurements. Abduction/adduction ratios using peak torques were significantly greater during concentric than eccentric actions. External/internal rotation ratios using average torques were significantly greater during eccentric than concentric actions. External/internal rotation ratios at 180 degrees/sec were significantly greater than those at 90 degrees/sec. No significant differences were observed between male and female subjects. Ratios were higher than previously reported. This was attributed to the scapular plane testing position. The clinician should be aware that shoulder strength ratios are dependent on position and that the scapular plane may be advantageous in some cases for testing and treatment.

Adult↗

PubMed1993

An overhead harness and trolly system for balance and ambulation assessment and training.

Safe assessment of standing balance and gait is often jeopardized by the potential for falls, which may have major physical and legal consequences. This article describes the design and use of a system that enhances the safety of the patient and clinician during balance and gait assessment and training. The system consists of an overhead track and moveable trolly that allows the patient, while secured in a simple body harness, the freedom to ambulate, perform functional types of activities, and fall with minimal risk of injury. As a result, a single therapist can more readily assess balance and ambulation, as well as provide training for these skills. In addition, the therapist is free to observe the patient's movements from any position, without direct physical contact. Practically, the system described may allow ambulation training sooner after injury or surgery, permit training in weight-bearing or partial weight-bearing activities with or without assistive devices, and allow the clinician to focus on assessment and training, rather than on patient safety.

Accidental Falls↗

PubMed1992

Knee extensor and knee flexor strength: cross-sectional area ratios in young and elderly men.

The relationships between isometric and isokinetic-concentric knee extensor and knee flexor strength, and quadriceps and hamstring cross-sectional area (CSA) were determined in young (n = 13, M = 24.5y) and elderly (n = 12, M = 70.7y) men. Quadriceps and hamstring CSA was determined by computed tomography. Knee extensor and flexor strength at 0 degree/s and 120 degree/s was determined on a Kin-Com isokinetic dynamometer. Compared to the young men, elderly men had significantly smaller quadriceps muscles and were weaker (22-32%) in knee flexion and knee extension at both angular velocities. Strength:CSA ratios were similar at 0 degree/s, but elderly men had decreased ratios for both extensors and flexors at 120 degree/s. Correlations of knee extensor and flexor strength with muscle CSA were significant at both velocities in elderly men, but not at either velocity for the knee flexors in young men. The decrease in isometric strength in elderly men can be accounted for by their decrease in muscle CSA, but their decrease in isokinetic-concentric strength was greater than their loss of CSA. Further study is required to determine the reason for this nonproportional loss of isokinetic-concentric strength.

Adult↗

PubMed1992

Eccentric and concentric torques of knee and elbow extension in young and older men.

The purpose of this study was to compare the strength of knee extensors and elbow extensors in young and older men under conditions of eccentric loading and concentric contractions. Twelve men ages 23 to 32 years and 12 ages 60 to 75 years were tested at two angular velocities of movement, 90 and 180 degrees.s-1, on a KinCom isokinetic dynamometer. Compared to young men, older men had lower concentric peak torque values for elbow (31%) and knee (32%) extensors (p less than 0.05). The older group showed lower eccentric peak torques on all elbow comparisons (21% lower), and for knee extension at the slower velocity (20%). At the faster velocity, knee extension eccentric peak torque did not differ from that of younger men. Differences between the age groups were significantly less for the eccentric muscle action than for the concentric one. The observation of maintained eccentric strength in older men, particularly at fast velocity, warrants research in defining the mechanism.

Adult↗

PubMed1991

Reliability of isometric hip abductor torques during examiner- and belt-resisted tests.

The purposes of this study were to determine the test-retest reliability of isometric hip abductor torques in elderly females, to compare two assessment protocols, and to compare the performances of elderly and young females. Twenty elderly and 20 young women were tested on two occasions. During the examiner-resisted test the examiner provided the resistance, and during the belt-resisted test the subject's contralateral leg provided the resistance while the examiner positioned the dynamometer. A four-way ANOVA indicated no occasion effects (p greater than .05). Within each group, similar torques were produced by both legs (p greater than .05). Test-retest intraclass reliability coefficients were good-to-high, ranging from 0.84 to 0.98 for the eight combinations of group-method-leg. The elderly females produced 61% of the torques produced by young females (p less than .01), and the examiner-resisted method produced 65% of the torques produced using the belt-resisted method (p less than .01). The belt-resisted method required less physical effort on the part of the tester, provided greater stabilization of the pelvis, and was preferred by 95% of the subjects.

Adult↗

PubMed1991

Effect of activation force on knee extensor torques.

The purpose of this study was to determine whether the magnitude of the activation force, defined as the force that must be applied to the load cell in order to activate the resistance arm of an isokinetic dynamometer, affected knee extensor torques. Twenty-four healthy female subjects performed resisted knee extension through the range of 95 degrees to 5 degrees knee flexion, with a 5-s rest between concentric and eccentric muscle actions. Six exercise sets, composed of the combinations of activation force (20,50, and 100 N) and angular velocity (45 and 135 degrees.s-1), were randomly assigned on each of two occasions, completed within a 10-d period. Although peak torques were not affected by the activation force, average torques, eccentric torques at mid-range (50 degrees knee flexion), and torques during the initial portion of each muscle action (80 degrees knee flexion during concentric muscle actions and 20 degrees flexion during eccentric actions) increased as the activation force increased. The effect of the activation force tended to be more pronounced during eccentric than during concentric muscle actions, and at the faster angular velocity. Comparisons of torques should be based on similar test protocols, including activation force.

Adult↗

PubMed1990

Eccentric knee strength of elderly females.

This study compared the strength of the knee extension and flexion muscles in groups of young and elderly women under two conditions: eccentric exercise in which the muscles were lengthened while subjects tried to resist an external force, versus concentric contractions in which the muscles shortened. Twenty-six females, aged 20 to 29 (Mean 25 +/- 3 SD), and 26 elderly women, aged 66 to 89 (Mean 73 +/- 6 SD), were tested at two angular velocities of movement, 45 degrees and 90 degrees/s, on a KinCom isokinetic dynamometer. Elderly women had significantly lower peak and average torque values in all comparisons with the young female group (25 to 54% lower, p less than .01). However, differences between the age groups were consistently smaller for the eccentric type of muscle action than the concentric, in both knee extensors and flexors.

Adult↗

PubMed1990

Lower extremity preference and knee extensor torques in intercollegiate soccer players.

The purpose of this study was to determine whether lower extremity preference influenced the relationship between the dominant and nondominant knee extensors of intercollegiate soccer players. Twelve recreational athletes and 12 soccer players completed isometric contractions at 60 degrees flexion, and concentric-eccentric contraction cycles at angular velocities of 60 degrees and 180 degrees/s through a range of motion from 90 degrees to 10 degrees knee flexion. Although the soccer players demonstrated greater peak and average torques, and greater differences between their dominant and nondominant legs, they responded similarly to recreational athletes during isometric, concentric and eccentric contractions and produced similar torque-velocity patterns. The concentric/eccentric ratios were similar for both legs and both groups, and decreased as angular velocity increased. The nondominant/dominant ratios of the soccer players, however, were significantly lower than those of the recreational athletes when calculated using peak torque (p less than .02) and nearly so when calculated using average torque (p less than .08). Nondominant/dominant ratios were not affected by the type of contraction or by the angular velocity. Further study is required to determine whether the small asymmetry (about 7%) in knee extensor strength of the soccer players is significant with respect to performance or injury rates, or may be inconsequential.

Adult↗

PubMed1990

Reliability of knee extensor and flexor torques during continuous concentric-eccentric cycles.

Peak and average torques of the knee extensors and flexors were determined on three occasions within ten days. On each occasion, 20 healthy women and 15 healthy men performed three continuous concentric-eccentric cycles with no pause between muscle actions or between cycles at 45 degrees and 90 degrees/sec angular velocities. Peak and average torques did not vary significantly or systematically over the three test occasions. Intraclass correlation coefficients (ICCs), based on one occasion, ranged from 0.79 to 0.91 for peak torques and from 0.75 to 0.88 for average torques. At 45 degrees/sec angular velocity, the ICCs for peak torque tended to be greater than those for average torque, whereas at 90 degrees/sec angular velocity the ICCs were similar whether calculated using peak or average torque. The ICCs during knee extension were greater than those during knee flexion. Eccentric muscle actions produced significantly higher torques than did concentric actions (p less than 0.01). A continuous concentric-eccentric cycle protocol which emphasizes teaching the subject to perform the test maneuvers and using at least three submaximal practice contractions and one maximal practice contraction can produce reliable isokinetic torques.

Adult↗

PubMed1987

Effect of electrical stimulation current frequencies on isometric knee extension torque.

The purpose of this study was to compare the isometric knee extension torques of male and female subjects during maximal voluntary contractions (MVCs), electrical stimulation only, and electrical stimulation superimposed onto MVCs at electrical stimulation current frequencies of 20, 50, and 100 Hz. An asymmetrical, bidirectional, nonionizing waveform of 1-msec pulse duration was delivered through the femoral nerve and the superficial quadriceps femoris muscles at maximally tolerated intensity for each subject. The male subjects (n = 20) demonstrated significantly greater absolute torques under all contraction conditions than did the female subjects (n = 20) (p less than .01); when the torques were expressed as a percentage of each subject's MVC torque, however, no significant differences were observed between the sexes. Overall, the superimposed contractions at 50 and 100 Hz and the MVCs had similar torque values, all being significantly greater than the torque values produced by electrical stimulation only at frequencies of 20, 50, and 100 Hz and by the superimposed contractions at 20 Hz. Superimposing electrical stimulation onto MVCs did not result in greater torques than those produced by the MVCs alone. The three most effective contraction conditions, in terms of subject comfort (minimal discomfort) and increased torque, were the superimposed contractions at 50 and 100 Hz and MVCs alone, all of which involved a voluntary component.

Adolescent↗

PubMed1987

Effects of dimethyl sulfoxide on systemic and cerebral hemodynamic variables in the ischemic canine myocardium.

The effects of dimethyl sulfoxide (DMSO) infusion on cerebral blood flow (CBF) and systemic hemodynamics were studied in a canine model of myocardial ischemia. Immediately after ligation, cardiac output dropped from 2.09 +/- 0.11 (SEM) in the control group and 1.79 +/- 0.13 in the DMSO group to 1.07 +/- 0.21 and 1.0 +/- 0.08 L/min, respectively; there were no significant differences for 2 h. By the third hour and thereafter, the DMSO group had a significantly (p less than .05) higher cardiac output (1.65 +/- 0.08 L/min) than the control group (1.15 +/- 0.10 L/min). The cardiac output increase at 3 h was accompanied by significantly (p less than .05) lower systemic vascular resistance (SVR) in the DMSO group (5315 +/- 248 dyne X sec/cm5) as compared to the control group (7892 +/- 442 dyne X sec/cm5). There were no significant differences in heart rate, mean arterial pressure, pulmonary artery wedge pressure, or cerebral or pulmonary resistances in the control as compared to the DMSO group. Higher CBF values were noted at one hour and thereafter in the DMSO as compared to the control group (p less than .05). Low-dose DMSO given as an iv bolus improved cardiac output and CBF and lowered SVR in this canine model of experimental myocardial ischemia.

Animals↗

PubMed1986

Head position trainer application for research and clinical use.

The head position trainer (HPT) is a frequently used biofeedback device for improving the head control of cerebral palsied children. When the HPT is used as a training or evaluative device, questions may arise regarding the consistency and accuracy of positioning it on the head and the position of the trainee's head. This article describes a technique for positioning and orienting the head and the HPT to one another and to common axes. With the subject in a supine position on a specially designed platform, the long axes of the zygomatic arch and the control box of the HPT were oriented vertically. The headband of the HPT then was tightened about the midforehead and the occipital areas. Reference marks were made on the forehead and the HPT was removed. After the subject assumed the sitting position, the HPT was reapplied using the forehead reference marks and the occipital areas as guides. Test-retest procedures were conducted using different therapists to apply the HPT to healthy and to handicapped subjects. The criterion score was the degrees difference between the long axes of the HPT control box and the zygomatic arch, an angle that would be 0 degree if the two long axes were parallel. No significant differences were observed between Trials 1 and 2, and the correlation coefficient between the two trials was statistically significant (p less than .02) in all situations. The HPT referencing platform can be constructed at minimal expense, and the technique of HPT application is relatively quick and reliable, and it produces minimal stress in handicapped subjects.

Adult↗

PubMed1985

Effect of therapeutic ultrasound intensity on subcutaneous tissue temperature and ulnar nerve conduction velocity.

Twenty subjects completed 5 min. periods of sonation, at each of six US intensities, over the ulnar nerve in the proximal forearm. All posttreatment NCV's differed significantly from the respective pretreatment velocities. The immediate posttreatment NCV associated with placebo US was significantly (p less than 0.01) less than that observed immediately pretreatment (2.81 m/s), while the five clinical US intensities produced significantly increased immediate posttreatment velocities: 0.5 w/cm2 (2.23 m/s) at (p less than 0.05), and 1.0 w/cm2 (2.78 m/s), 1.5 w/cm2 (3.15 m/s), 2.0 w/cm2 (4.47 m/s) and 2.5 w/cm2 (2.97 m/s) at (p less than 0.01). The posttreatment velocities associated with the five clinical intensities were all significantly greater (p less than 0.01) than that associated with placebo US. Subcutaneous tissue temperatures were directly related to the intensity of US. Not until US intensity had reached 1.5 w/cm2 did the heating effect of US negate the cooling effect of the US transmission gel, to produce significantly increased subcutaneous tissue temperatures after 5 min. sonation. The decreased ulnar motor NCV's associated with placebo US are attributed to the cooling effect of the US transmission gel. The increased ulnar motor NCV's associated with the clinical intensities of US are attributed to the deep heating effect of US. The breakdown of this linear relationship at 2.5 w/cm2 intensity suggests that at this point heating on the nerve and/or the mechanical effects of US were of sufficient magnitude so as to limit the increase in conduction velocity. Sonation over an area of approximately 4.5 times the soundhead for 5 min., along the proximal forearm, at clinical intensities did not have a bipositive effect on motor NCV.

Adult↗