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Biomedical subjects

D H Nielsen

Publications and source records attributed to D H Nielsen.

At least 19 recordsLinked to original sources
PubMed2000

New equations improve NIR prediction of body fat among high school wrestlers.

STUDY DESIGN: Methodologic study to derive prediction equations for percent body fat (%BF). OBJECTIVES: To develop valid regression equations using NIR to assess body composition among high school wrestlers. BACKGROUND: Clinicians need a portable, fast, and simple field method for assessing body composition among wrestlers. Near-infrared photospectrometry (NIR) meets these criteria, but its efficacy has been challenged. METHODS AND MEASURES: Subjects were 150 high school wrestlers from 2 Midwestern states with mean +/- SD age of 16.3 +/- 1.1 yrs, weight of 69.5 +/- 11.7 kg, and height of 174.4 +/- 7.0 cm. Relative body fatness (%BF) determined from hydrostatic weighing was the criterion measure, and NIR optical density (OD) measurements at multiple sites, plus height, weight, and body mass index (BMI) were the predictor variables. RESULTS: Four equations were developed with multiple R2s that varied from .530 to .693, root mean squared errors varied from 2.8% BF to 3.4% BF, and prediction errors varied from 2.9% BF to 3.1% BF. The best equation used OD measurements at the biceps, triceps, and thigh sites, BMI, and age. The root mean squared error and prediction error for all 4 equations were equal to or smaller than for a skinfold equation commonly used with wrestlers. CONCLUSION: The results substantiate the validity of NIR for predicting % BF among high school wrestlers. Cross-validation of these equations is warranted.

Adipose Tissue↗
PubMed1999

Physiological measurements of walking and running in people with transtibial amputations with 3 different prostheses.

STUDY DESIGN: A 3-factor (foot type, speed, and mode of ambulation) repeated-measures experimental design was used. OBJECTIVES: To compare the differences in energy expenditure, gait efficiency, and relative exercise intensity in persons with transtibial amputations with various prostheses. BACKGROUND: There is a need for improved prosthetic designs to accommodate physically active persons with lower-extremity amputations. METHODS AND MEASURES: We used progressive speeds of treadmill walking (53.64, 67.05, 80.46, 93.87, and 107.28 m/min) and running (120.69, 134.1, and 147.51 m/min) with 3 different types of prostheses: the Solid Ankle Cushion Heel (SACH) foot, the Flex-Foot (FF), and the Re-Flex Vertical Shock Pylon (VSP) prosthesis. Five physically active men with unilateral transtibial amputations served as subjects (aged 31.6 +/- 4.28 years). RESULTS: The following statistically significant differences (improvements) between the Re-Flex VSP versus the FF and the SACH foot were found. Energy cost: walking (5%), running (11%); gait efficiency: walking (6%), running (9%); relative exercise intensity: walking (4%), running (5%). However, we found no significant differences between the FF and the SACH. CONCLUSIONS: The Re-Flex VSP appears to have a positive effect on energy cost, efficiency, and relative exercise intensity compared with the other prosthetic foot types during walking and running.

Adult↗
PubMed1995

Altered insulin resistance is associated with increased dietary weight loss in obese children.

To determine the relationship between insulin resistance and weight loss in early obesity, we used the euglycemic, hyperinsulinemic clamp to study the effect of a 14-day weight reduction diet in 10 prepubertal and early pubertal obese children (age, 10.1 +/- 1.6 years) on insulin sensitivity. Body weight decreased from 73.7 +/- 6.0 kg to 69.1 +/- 5.8 kg (p < 0.01). Insulin sensitivity before weight reduction negatively correlated with the amount of weight loss during diet (r = -0.8, p < 0.005). Weight loss also positively correlated with height standard deviation score (r = 0.9, p < 0.005). Mean insulin sensitivity increased from 0.068 +/- 0.01 (nmol kg-1 min-1)/(pmol l-1) to 0.096 +/- 0.030 (nmol kg-1 min-1)/(pmol l-1) (p < 0.05, one-tailed test). These results indicate that weight reduction decreases insulin resistance in childhood obesity. The inverse relationship between insulin sensitivity and weight loss during calorie, restriction in these subjects suggests that insulin resistance may enhance weight loss during calorie restriction.

Blood Glucose↗
PubMed1993

Cross-validation of bioelectrical impedance analysis of body composition in children and adolescents.

BACKGROUND AND PURPOSE: The reliability and validity of measurements obtained with two bioelectrical impedance analyzers (BIAs), an RJL Systems model BIA-103 and a Berkeley Medical Research BMR-2000, were investigated using the manufacturers' prediction equations for the assessment of fat-free mass (FFM) (in kilograms) in children and adolescents. SUBJECTS: Forty-seven healthy children and adolescents (23 male, 24 female), ranging in age from 8 to 20 years (mean = 12.1, SD = 2.3), participated. METHODS: In the context of a repeated-measures design, the data were analyzed according to gender and maturation (Tanner staging). Hydrostatic weighing (HYDRO) and Lohman's Siri age-adjusted body density prediction equation served as the criteria for validating the BIA-obtained measurements. RESULTS: High intraclass correlation coefficients (ICC > or = .987) demonstrated good test-retest (between-week) measurement reliability for HYDRO and both BIA methods. Between-method (HYDRO versus BIA) correlation coefficients were high for both boys and girls (r > or = .97). The standard errors of estimate (SEEs) for FFM were slightly larger for boys than for girls and were consistently smaller for the RJL system than for the BMR system (RJL SEE = 1.8 kg for boys, 1.3 kg for girls; BMR SEE = 2.4 kg for boys, 1.9 kg for girls). The coefficients of determination were high for both BIA methods (r2 > or = .929). Total prediction errors (TEs) for FFM showed similar between-method trends (RJL TE = 2.1 kg for boys, 1.5 kg for girls; BMR TE = 4.4 kg for boys, 1.9 kg for girls). DISCUSSION AND CONCLUSION: This study demonstrated that the RJL BIA with the manufacturer's prediction equations can be used to reliably and accurately assess FFM in 8- to 20-year-old children and adolescents. The prediction of FFM by the BMR system was acceptable for girls, but significant overprediction of FFM for boys was noted.

Adolescent↗
PubMed1993

Validity of near infrared body composition analysis in children and adolescents.

The purpose of this study was to evaluate the validity and reliability of the Futrex 5000A near infrared (NIR) spectrophotometer for the assessment of body composition in children and adolescents. Forty-eight subjects (24 boys and 24 girls) with a mean age of 12.7 +/- 2.7 yr underwent three methods of body composition testing: NIR, densitometry by hydrostatic weighing (HYDRO), and skinfold anthropometry (SKF). Percent body fat (%BF) and fat free mass (FFM) derived from the Lohman's age-adjusted Siri equation served as the criterion. Within session test-retest reliability was determined for the NIR device for all subjects and between-week reliability was evaluated for all test methods in 14 subjects. Based on the excellent within- and between-session reliability (ICC ranged from 0.907-0.999), the system offers the potential of obtaining longitudinal data in growth and development studies. However, the significant mean differences, moderate correlations with the criterion (r = 0.62-0.71) and inflated standard errors of estimate (SEE = 4.9-5.5% BF, 2.2-2.9 kg FFM) and total prediction errors (TE = 5.5-8.0% BF, 2.7-3.7 kg FFM) indicate that refinement of prediction equations is needed to establish the measurement validity. Continued research with expanded populations is needed to further demonstrate and evaluate the utility of this device.

Adipose Tissue↗
PubMed1993

Cross-validation of the Slaughter skinfold equations for children and adolescents.

Prior to sexual maturation, children and adolescents have more water and less bone mineral content than adults, resulting in less dense fat-free body mass (FFM). This suggests that previously established adult skinfold/density equations are inappropriate for use with children and adolescents for the prediction of body fatness (%BF) and FFM. To overcome this problem, Slaughter and colleagues have introduced new skinfold (SKF) equations that take into account the changing density of FFM in children and adolescents as they mature. The purpose of our study was to cross-validate a select set of the Slaughter SKF equations by comparing them with a criterion measurement (Lohman's Siri age-adjusted body density equation) in 122 subjects ranging in sexual maturation from pre- to post-pubescent and ranging in age from 8-17. Our cross-validation found very high intraclass (reliability) correlations (ICCs = 0.98-0.99) and high validity correlations (rs = 0.79-0.99). The standard errors of the estimate for %BF ranged from 3.5-4.6% and total errors for %BF ranged from 3.6-4.6%. The Slaughter equation using tricep and calf SKF for females was significantly different (P < 0.05) from the criterion measure in its prediction of %BF. In males, there was an interaction between the SKF equation and subject maturation level. The data indicate that the Slaughter SKF equations hold promise for estimating body composition in children and adolescents but are still in need of refinement.

Adipose Tissue↗
PubMed1992

Cardiorespiratory responses of healthy subjects to calisthenics performed on land versus in water.

This study evaluated the oxygen consumption (VO2) and heart rate response curves for standardized upper- and lower-extremity exercise on land and in water. Forty healthy subjects performed one upper-extremity and one lower-extremity exercise at three selected cadences on land and in water. Steady-state heart rate was determined by electrocardiographic radiotelemetry and expressed as a percentage of age-predicted maximal heart rate (% APMHR). Percentage of age-predicted maximal heart rate was used as the criterion measure of relative exercise intensity. Oxygen consumption was determined by the open-circuit method. Results indicated systematic increases in VO2 from 2 to 9 metabolic equivalents (METs) (1 MET = 3.5 mL O2.kg-1.min-1) and % APMHR from 45% to 73% with increased cadence. The VO2 responses were highest during water exercise, whereas % APMHR was greater during land exercise. Based on the magnitude of the responses, water calisthenics appear to be of sufficient intensity to elicit training adaptations. Training studies are needed to document these changes.

Adult↗
PubMed1991

Wrestlers' minimal weight: anthropometry, bioimpedance, and hydrostatic weighing compared.

The need for accurate assessment of minimal wrestling weight among interscholastic wrestlers has been well documented. Previous research has demonstrated the validity of anthropometric methods for this purpose, but little research has examined the validity of bioelectrical impedance (BIA) measurements. Comparisons between BIA systems has received limited attention. With these two objectives, we compared the prediction of minimal weight (MW) among 57 interscholastic wrestlers using three anthropometric methods (skinfolds (SF) and two skeletal dimensions equations) and three BIA systems (Berkeley Medical Research (BMR), RJL, and Valhalla (VAL]. All methods showed high correlations (r values greater than 0.92) with hydrostatic weighting (HW) and between methods (r values greater than 0.90). The standard errors of estimate (SEE) were relatively small for all methods, especially for SF and the three BIA systems (SEE less than 0.70 kg). The total errors of prediction (E) for RJL and VAL (E = 4.4 and 3.9 kg) were significantly larger than observed nonsignificant BMR and SF values (E = 2.3 and 1.8 kg, respectively). Significant mean differences were observed between HW, RJL, VAL, and the two skeletal dimensions equations, but nonsignificant differences were observed between HW, BMR, and SF. BMR differed significantly from the RJL and VAL systems. The results suggest that RJL and VAL have potential application for this subpopulation. Prediction equation refinement with the addition of selected anthropometric measurement or moderating variables may enhance their utility. However, within the scope of our study, SF and BMR BIA appear to be the most valid methods for determining MW in interscholastic wrestlers.

Adolescent↗
PubMed1990

Validity and reliability testing of the Scoliometer.

This study was designed to evaluate the Scoliometer, an instrument that measures axial trunk rotation in individuals with scoliosis. The objectives included determining 1) the Scoliometer's screening capability and validity and 2) the intrarater and interrater reliability of Scoliometer measurements. Scoliometer measurements made by two raters on 65 persons with idiopathic scoliosis were correlated with radiographic assessment of vertebral (pedicle) rotation and lateral curvature (Cobb method). Correlation ranged from .32 to .46 with pedicle rotation and from .46 to .54 with the Cobb angle. Frequency analysis revealed relatively good specificity, sensitivity, and predictive capability of the Scoliometer. Intrarater and interrater reliability coefficients were high (r = .86-.97). These results indicate good measurement reproducibility. The less-than-optimal between-method correlation coefficients suggest that the validity of Scoliometer measurements is not sufficient to use this method alone for determining patient diagnosis and management. Based on the positive-frequency analysis, however, the use of this tool as a screening device would be appropriate.

Adolescent↗
PubMed1990

Energy cost, exercise intensity, and gait efficiency of standard versus rocker-bottom axillary crutch walking.

The purpose of this study was to investigate differences in selected biomechanical and physiological measurements and subjective preferences for ambulation with the standard single-tip axillary crutch versus the rocker-bottom-type axillary crutch. Self-selected walking velocities (S-SWVs) and stride length for each crutch type were determined for a two-point, non-weight-bearing, swing-through gait in 24 healthy volunteers. Relative exercise intensity, oxygen uptake (VO2), and gait efficiency were assessed for each crutch type at both S-SWVs. Subjects negotiated two architectural barriers (stairs and ramp) and completed a subjective questionnaire concerning crutch preferences. Walking with either crutch type resulted in slower S-SWVs, greater VO2, higher relative exercise intensity, and reduced gait efficiency compared with values for normal unassisted ambulation. An analysis of variance for these variables revealed nonsignificant between-crutch differences. Based on the subjective data, a preference for the standard single-tip crutch was evident. Within the scope of the study, the results supported no apparent advantage relative to energy expenditure to using the rocker-bottom crutch.

Adult↗
PubMed1987

Intrarater reliability of manual muscle testing and hand-held dynametric muscle testing.

Physical therapists require an accurate, reliable method for measuring muscle strength. They often use manual muscle testing or hand-held dynametric muscle testing (DMT), but few studies document the reliability of MMT or compare the reliability of the two types of testing. We designed this study to determine the intrarater reliability of MMT and DMT. A physical therapist performed manual and dynametric strength tests of the same five muscle groups on 11 patients and then repeated the tests two days later. The correlation coefficients were high and significantly different from zero for four muscle groups tested dynametrically and for two muscle groups tested manually. The test-retest reliability coefficients for two muscle groups tested manually could not be calculated because the values between subjects were identical. We concluded that both MMT and DMT are reliable testing methods, given the conditions described in this study. Both testing methods have specific applications and limitations, which we discuss.

Adult↗
PubMed1986

Transcutaneous electrical nerve stimulation characteristics for altering pain perception.

The purpose of this study was to determine the effect of conventional low-intensity transcutaneous electrical nerve stimulation (TENS) waveform and frequency characteristics on experimentally induced acute pain. Each of 28 male subjects received six forms of TENS and one control treatment during a single testing session. Treatments used one of two waveforms (monophasic or biphasic) and one of three frequencies (30, 60, or 85 Hz) administered to the forearm. Treatment effects were ascertained from alterations in pain-threshold and pain-tolerance responses induced by noxious electrical stimulation of the ipsilateral fifth digit. The TENS waveform and frequency had a negligible effect on pain threshold. The results indicated that waveform did not influence pain tolerance significantly. Pain tolerance, however, increased significantly at the frequency of 60 Hz but decreased significantly at both 30 and 85 Hz (p less than .05). We concluded that TENS frequency is an important factor in altering the subjects' perception of experimentally induced pain.

Adult↗
PubMed1986

Ambulation of children with myelomeningocele: parapodium versus parapodium with Orlau swivel modification.

The feasibility of ambulation for children with high spinal lesions is questionable because of the relatively high exercise intensity and energy cost required, so orthotics designed for ambulation must keep energy expenditure to a minimum. This study determined the self-selected walking velocity and maximum walking velocity of 10 paraplegic children using two orthotic devices, the parapodium and swivel walker, and compared the energy cost, gait efficiency and relative exercise intensity (per cent maximum heart-rate). Walking velocities were significantly higher with the parapodium, but energy cost and gait efficiency were significantly better with the swivel walker. Differences between the two devices in relative exercise intensity were not significant. Although walking velocity is slower, the lower metabolic cost appears to give the swivel walker an advantage over the parapodium.

Child↗
PubMed1985

Fatal ventricular fibrillation following verapamil in Wolff-Parkinson-White syndrome with atrial fibrillation.

A 29-year-old man with Wolff-Parkinson-White syndrome and atrial fibrillation developed fatal ventricular fibrillation shortly after receiving intravenous verapamil. The patient presented with an irregular pulse of 190. A total of 23 mg of verapamil was administered in small intravenous doses over 35 minutes. The ventricular rate accelerated as verapamil was administered, and fatal ventricular fibrillation followed. Three theoretical mechanisms by which verapamil may enhance conduction of atrial fibrillation in Wolff-Parkinson-White syndrome, predisposing to ventricular fibrillation, are mentioned.

Adult↗
PubMed1985

Scope of cardiac rehabilitation.

The focus of this article is on the acute care and rehabilitation of the patient with coronary artery disease. The purpose is to provide an overview of the clinical treatment used at the University of Iowa Hospital, for the practicing physical therapist who may be unfamiliar with this type of patient. The three primary phases of the cardiac rehabilitation program are discussed with emphasis on the treatment of the patient with a post-myocardial infarction. Specific guidelines regarding evaluation and progression of physical activity are provided.

Coronary Disease↗
PubMed1985

Normal cardiopulmonary responses to acute- and chronic-strengthening and endurance exercises.

The purpose of this article is to provide background information concerning the cardiopulmonary responses to physical exercise. The focus is on acute and chronic responses to both strengthening and endurance exercise. Knowledge of normal exercise physiology provides the frame of reference for comparison with abnormal responses, especially as exercise relates to patients with cardiovascular disease.

Blood Pressure↗