Professor Arthur T. Johnson

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Publications & Abstracts: Biomechanics

 

MAXIMUM STATIC INSPIRATORY AND EXPIRATORY PRESSURES WITH DIFFERENT LUNG VOLUMES

BioMedical Engineering OnLine 2006, 5:29
doi: 10.1186/1475-925X-5-29

This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Christopher G Lausted
Arthur T Johnson
William H Scott
Monique M JohnsoX
Karen M Coyne
Derya C Coursey

ABSTRACT
Maximum pressures developed by the respiratory muscles can indicate the health of the respiratory system, help to determine maximum respiratory flow rates, and contribute to respiratory power development. Past measurements of maximum pressures have been found to be inadequate for inclusion in some exercise models involving respiration.

Maximum inspiratory and expiratory airway pressures were measured over a range of lung volumes in 29 female and 19 male adults. A commercial bell spirometry system was programmed to occlude airflow at nine target lung volumes ranging from 10% to 90% of vital capacity.

In women, maximum expiratory pressure increased with volume from 39 to 61 cmH2O and maximum inspiratory pressure decreased with volume from 66 to 28 cmH2O. In men, maximum expiratory pressure increased with volume from 63 to 97 cmH2O and maximum inspiratory pressure decreased with volume from 97 to 39 cmH2O. Equations describing pressures for both sexes are:

Pe/Pmax = 0.1426 Ln(%VC) + 0.3402 R2 = 0.95
Pi/Pmax = 0.234 Ln(100 - %VC) - 0.0828 R2 = 0.96

These results were found to be consistent with values and trends obtained by other authors. Regression equations may be suitable for respiratory mechanics models.

 

LOWER LEG HIGH-INTENSITY RESISTANCE TRAINING AND PERIPHERAL HEMODYNAMIC ADAPTATIONS

Can. J. Appl. Physiol. 21(3): 209-217 (1996)

Vernon Bond, Jr.
Paul Wang
Richard G. Adams
Arthur T. Johnson
Paul Vaccaro
Russell J. Tearney
Richard M. Millis
B. Don Franks
David R. Bassett, Jr.

ABSTRACT
High-intensity resistance (HIR) training has been associated with muscle hypertrophy and decreased microvascular density that might produce a blood flow limitation. The effect of HIR training on lower leg maximal blood flow and minimum vascular resistance (Rmin) during reactive hyperemia were investigated in 7 healthy males. The gastrocnemius-soleus muscles of one leg were trained using maximal isokinetic concentric contractions for 4 weeks; the nontrained leg was the control. Lower leg blood flow was measured by venous occlusion plethysmography. Lower leg muscle volume was determined using magnetic resonance imaging. Peak isokinetic torque increased in both the trained (T) and nontrained (NT) legs (p < .05). Lower leg muscle volume increased by 2% in the T leg only (p < .05). In the T leg, maximal bloodflow decreased and Rmin increased (p < .05); no hemodynamic change was detected in the NT leg. It is concluded that HIR training of the calf muscles is associated with a decrease in hyperemia-induced blood flow; thereby, indicating a blood flow limitation to the calf muscles.

Key words: Isokinetic strength training, reactive hyperemia

 

THE CHANGE IN INITIAL LUNG VOLUME DURING EXERCISE

IEEE Transactions on Biomedical Engineering, Vol. 42, No., 3. March 1995

Arthur T. Johnson

ABSTRACT
The lung volumes from which inhalation and exhalation proceed change during exercise. There have been previous attempts to predict these lung volumes but none have been completely successful. Prediction of initial lung volume is important in the accurate calculation of respiratory power during exercise, especially when the subject is encumbered with respiratory protective apparatus and exercising above the anaerobic threshold. Although there is no direct work advantage to varying lung volumes at the beginning of inspiration or expiration, such changes appear to be dictated by the asymmetry of lung recoil pressure about the lung relaxation volume. Equalizing inspiratory and expiratory elastic pressures has been found to match available data on lung initial volume.

 

HOW MUCH WORK IS EXPENDED FOR RESPIRATION?

Frontiers Med. Biol. Engng, Vol. 5, No. 4, pp. 265-287 (1993)

Arthur T. Johnson

ABSTRACT
The rate of work expended to move air in the respiratory system has been determined for five different airflow waveshapes, a non-linear respiratory model and five exercise levels. As expected, the rectangular waveshape was the most efficient. Model conditions were then changed one at a time: (i) starting lung volume was allowed to vary, (ii) exhalation flow limitation was added, (iii) respiration was considered to be a metabolic burden determining part of the ventilation requirement and (iv) a respirator mask was added. Although there is no direct work advantage to varying initial lung volume, such volume changes appear to be dictated by the asymmetry of lung recoil pressure about the lung relaxation volume; allowing the work of respiration to become a metabolic burden clearly shows why respiratory waveforms change from rest to exercise; and, adding a respirator imposes a severe respiratory burden on the wearer engaging in moderate, heavy and very heavy exercise.

Key words: respiration; work.

 

MODELLING EXERCISE-INDUCED PULMONARY HEMORRHAGE IN RACING THOROUGHBREDS

Frontiers Med. Biol. Engng, Vol. 4, No. 4, pp. 271-289 (1992)

Arthur T. Johnson
Lawrence R. Soma
Carmella Ferouz

ABSTRACT
Exercise-induced pulmonary hemorrhage (EIPH) affects a large portion of racing thoroughbred horses. Sites of hemorrhage and causal mechanisms remain unestablished. Our mathematical model was constructed to test the hypothesis that EIPH could be caused by a combination of respiratory and circulatory mechanical factors occurring during exercise. Various physiological data for respiration, blood circulation and exercise were incorporated into the model. Results show that inhalation pressure drops across airway resistances become great enough during exercise to cause rupture of capillaries for both bronchial and pulmonary systems.

Key words: horses; exercise; respiration; pulmonary system; capillary bursting.

 

AIRFLOW RESISTANCE OF CONSCIOUS BOARS

Transactions of the ASAE, Vol. 26, No. 4, pp. 1150-1152, 1983

Arthur T. Johnson
Chin-Shing Lin

ABSTRACT
The Airflow Perturbation Device (APD) was used to measure airway resistance of conscious caged boars. Although the pigs resisted the measurement, sufficient data was obtained to give an average value of airway resistance of 0.97 cm H2O-s/L for the eight pigs tested. Values are in the expected range, and exhalation resistance is higher than inhalation resistance, also as expected. Plots of resistance within each breath for two different pigs apparently show the dominance in one of the flow rate effect on resistance and in the other of the lung volume effect.

 

BIOMECHANICS IN AGRICULTURE

Perspectives in Biomechanics, D. N. Ghista, ed., Harwood: New York, 1980

Arthur T. Johnson

ABSTRACT
Biomechanical analyses of agricultural problems have contributed greatly to the steady improvement of agricultural productivity. As the range of agricultural endeavors is broad, so is the range of problems which have been approached by agribioengineers. The objective of this chapter is to sample some biomechanical approaches to demonstrate this breadth. Accordingly, examples have been selected highlighting mechanical harvesting, flow of biological materials, plant models, product processing, thermal models, and human biomechanics.

 

PREDICTION OF INHALATION TIME/EXHALATION TIME RATIO DURING EXERCISE

IEEE Transactions on Biomedical Engineering, Vol., BME-23, No. 5, September 1976

Arthur T. Johnson
Ceslovas Masaitis

ABSTRACT
Using a criterion of minimization of total respiratory work during a complete respiratory cycle, an expression has been derived for prediction of the inhalation time/exhalation time ratio. Comparison of calculated results to experimental data is favorable. The expression also predicts a rectangular waveshape during exercise, and this result agrees well with experimental and theoretical findings previously published.

 

A COMPUTER MODEL TO ANALYZE AND SIMULATE THERMORECEPTOR ACTION

Transactions of the ASAE, Vol. 14, No. 5, pp. 828-836 and 840, 1971

A. T. Johnson
Norman R. Scott

ABSTRACT
Thermoreceptors are means by which humans and animals receive information about their thermal environment. A computer model based on the Hodgkin-Huxley equations was formulated to simulate thermoreceptor action. Simulated thermoreceptors can be used as a component of larger thermal models of animals.

 

MEASUREMENT OF HYPOTHALAMIC TEMPERATURE AND HEART RATE OF POULTRY

Transactions of the ASAE, Vol. 13, No. 3, pp. 342-347, 1970

Norman R. Scott
Arthur T. Johnson
A. Van Tienhoven

ABSTRACT
Hypothalamic temperature is a key element in thermoregulation of poultry. To measure this temperature, a probe inserted into the brain was made from a 23 gage hypodermic needle containing a miniature copper-constantan thermocouple. Heart rate was obtained using a miniature FM transmitter affixed to the bird's back. Both hypothalamic temperature and heart rate were found to fluctuate over the monitoring period. They exhibited diurnal variation, and were affected by level of arousal, activity, sleep, and feeding. The maximum daily hypothalamic temperature corresponded to the time of oviposition.