Mechanical work of breathing during exercise in trained and untrained subjects

1962 ◽  
Vol 17 (1) ◽  
pp. 43-46 ◽  
Author(s):  
G. Milic-Emili ◽  
J. M. Petit ◽  
R. Deroanne
Keyword(s):  
Oxygen Uptake ◽  
Tidal Volume ◽  
Work Of Breathing ◽  
Pulmonary Ventilation ◽  
Esophageal Pressure ◽  
Bicycle Ergometer ◽  
Mechanical Work ◽  
Trained Subjects

The mechanical work of breathing was measured from simultaneous records of esophageal pressure and tidal volume on seven well trained and seven untrained subjects exercising on a bicycle ergometer. At any given value of pulmonary ventilation, mechanical work of breathing was found to be the same for untrained and trained subjects. At any given value of oxygen uptake, pulmonary ventilation and, accordingly, mechanical work of breathing were found to be smaller in trained than in untrained individuals. Submitted on June 9, 1961

Mechanical work of breathing during muscular exercise

1960 ◽  
Vol 15 (3) ◽  
pp. 354-358 ◽  
Author(s):  
R. Margaria ◽  
G. Milic-Emili ◽  
J. M. Petit ◽  
G. Cavagna
Keyword(s):  
Energy Cost ◽  
Work Of Breathing ◽  
Pulmonary Ventilation ◽  
Respiratory Muscles ◽  
Mechanical Efficiency ◽  
Mechanical Work ◽  
Muscular Exercise ◽  
Additional Energy ◽  
External Work ◽  
Small Magnitude

The mechanical work of breathing was measured during muscular exercise on three normal subjects from simultaneous records of intra-esophageal pressure and tidal volume. At the maximal values of ventilation attained during exercise, the mechanical work of breathing amounts to about 100–120 cal/min. The maximum pulmonary ventilation useful for external work is attained when the energy cost of breathing due to any additional unit of air ventilated (dWre/dV) equals the additional energy provided by the same change in ventilation (dWtot/ dV), i.e. when dWre/dV = dWtot/dV. The maximal values of ventilation obtained experimentally during muscular exercise are in good agreement with that assumption, if the mechanical efficiency of the respiratory muscles is taken as 0.25. This implies that the mechanical efficiency of the respiratory muscles is the same as that of the muscles involved in performing useful external work. The work of breathing is of relatively small magnitude: during exercise the work of a breathing cycle amounts, at maximum, to 8% of the maximum potential work of breathing, calculated from the pressure-volume diagram of the respiratory apparatus, and the energy cost of respiration represents no more than 3% of the total energy consumed by the subject. Submitted on May 21, 1959

Metabolic and cardiopulmonary responses to wheelchair and bicycle ergometry

1979 ◽  
Vol 46 (6) ◽  
pp. 1066-1070 ◽  
Author(s):  
R. M. Glaser ◽  
M. N. Sawka ◽  
L. L. Laubach ◽  
A. G. Suryaprasad
Keyword(s):  
Heart Rate ◽  
Oxygen Uptake ◽  
Power Output ◽  
Respiratory Exchange Ratio ◽  
Pulmonary Ventilation ◽  
Mechanical Efficiency ◽  
Bicycle Ergometer ◽  
Upper Body ◽  
Bicycle Ergometry ◽  
Ventilatory Equivalent

To evaluate wheelchair activity in reference to a more familiar mode of locomotion, metabolic and cardiopulmonary responses to wheelchair ergometer (WERG) and bicycle ergometer (BERG) exercise were compared. Eighteen able-bodies subjects were tested on a combination wheelchair-bicycle ergometer. Oxygen uptake (VO2), respiratory exchange ratio (R), pulmonary ventilation (VE), ventilatory equivalent (VE/VO2), percent net mechanical efficiency (ME), and heart rate (HR) were determined at power output (PO) levels of 30, 90, and 150 kpm/min on each ergometer. For WERG and BERG exercise, VO2, VE, and HR increased linearly with PO. Generally, VO2, R, VE, VE/VO2, and HR responses were higher (P less than 0.05) during WERG than BERG exercise at each PO. Blood lactate was determined after 150 kpm/min, and found to be higher (P less than 0.05) during WERG than BERG exercise. ME increased with PO and was lower (P less than 0.05) for WERG than BERG exercise at each PO level. The greater metabolic and cardiopulmonary responses observed during WERG exercise may be due to inefficient biomechanics and the relatively small upper body musculature used for propulsion.

Effect of Synchronized Intermittent Mandatory Ventilation on Respiratory Workload in Infants after Cardiac Surgery

2001 ◽  
Vol 95 (4) ◽  
pp. 881-888 ◽  
Author(s):  
Hideaki Imanaka ◽  
Masaji Nishimura ◽  
Hiroshi Miyano ◽  
Hideki Uemura ◽  
Toshikatsu Yagihara
Keyword(s):  
Cardiac Surgery ◽  
Tidal Volume ◽  
Minute Ventilation ◽  
Work Of Breathing ◽  
Esophageal Pressure ◽  
Intermittent Mandatory Ventilation ◽  
Negative Deflection ◽  
Arterial Blood ◽  
Pressure Time ◽  
Post Cardiac Surgery

Background Synchronized intermittent mandatory ventilation (SIMV) is commonly used in infants and adults. However, few investigations have examined how SIMV reduces respiratory workload in infants. The authors evaluated how infants' changing respiratory patterns when reducing SIMV rate increased respiratory load. The authors also investigated whether SIMV reduces infant respiratory workload in proportion to the rate of mandatory breaths and which rate of SIMV provides respiratory workloads similar to those after tracheal extubation. Methods When 11 post-cardiac surgery infants aged 2-11 months were to be weaned with SIMV, the authors randomly applied five levels of mandatory breathing: 0, 5, 10, 15, and 20 breaths/min. All patients underwent ventilation with SIMV mode: pressure control ventilation, 16 cm H2O; inspiratory time, 0.8 s; triggering sensitivity, 0.6 l/min; and positive endexpiratory pressure, 3 cm H2O. After establishing steady-state conditions at each SIMV rate, arterial blood gases were analyzed, and esophageal pressure, airway pressure, and airflow were measured. Inspiratory work of breathing, pressure-time products, and the negative deflection of esophageal pressure were calculated separately for assisted breaths, for spontaneous breaths, and for total breaths per minute. Measurements were repeated after extubation. Results As the SIMV rate decreased, although minute ventilation and arterial carbon dioxide tension were maintained at constant values, spontaneous breathing rate and tidal volume increased. Work of breathing, pressure-time products, and negative deflection of esophageal pressure increased as the SIMV rate decreased. Work of breathing and pressure-time products after extubation were intermediate between those at a SIMV rate of 5 breaths/min and those at 0 breaths/min. Conclusion When the load to breathing was increased progressively by decreasing the SIMV rate in post-cardiac surgery infants, tidal volume and spontaneous respiratory rate both increased. In addition, work of breathing and pressure-time products were increased depending on the SIMV rate.

Relative Stresses of Wheelchair Activityl

1980 ◽  
Vol 22 (2) ◽  
pp. 177-181 ◽  
Author(s):  
Roger M. Glaser ◽  
Stephen A. Barr ◽  
Lloyd L. Laubach ◽  
Michael N. Sawka ◽  
Agaramg G. Suryaprasad
Keyword(s):  
Heart Rate ◽  
Oxygen Uptake ◽  
Respiratory Exchange Ratio ◽  
Pulmonary Ventilation ◽  
Bicycle Ergometer ◽  
Acute Exposure ◽  
Bicycle Exercise ◽  
Rest Periods ◽  
Ventilatory Equivalent

To study relative stresses of wheelchair activity, seven able-bodied subjects' metabolic (oxygen uptake) and cardiopulmonary (heart rate and pulmonary ventilation) responses were determined during wheelchair (arm stroking) and bicycle (leg pedaling) exercise at identical propulsion velocities and work rates. For this, subjects exercised on a combination wheelchair-bicycle ergometer at wheel velocities of 1.17, 2.34, and 3.51 km/hr. The six bouts of exercise were intennittent~5-min exercise periods interspersed by 10-min rest periods. At 1.17 km/hr, no significant differences were found between wheelchair and bicycle exercise for each of the monitored variables. At 2.34 and 3.51 km/hr, however, all responses were significantly higher for wheelchair exercise. At these higher velocities, calculated respiratory exchange ratio and ventilatory equivalent values were also significantly higher for wheelchair exercise. These results suggest that acute exposure to wheelchair activity could be relatively stressful and could limit rehabilitative efforts.

Oxygen uptake during the first minutes of heavy muscular exercise

1961 ◽  
Vol 16 (6) ◽  
pp. 971-976 ◽  
Author(s):  
Per-Olof Åstrand ◽  
Bengt Saltin
Keyword(s):  
Heart Rate ◽  
Lactic Acid ◽  
Oxygen Uptake ◽  
Aerobic Capacity ◽  
Pulmonary Ventilation ◽  
Peak Oxygen Uptake ◽  
Bicycle Ergometer ◽  
Muscular Exercise ◽  
Work Time ◽  
Submaximal Work

Oxygen uptake, heart rate, pulmonary ventilation, and blood lactic acid were studied in five subjects performing maximal work on a bicycle ergometer. After a 10-min warming up period work loads were varied so that exhaustion terminated exercise after about 2—8 min. Peak oxygen uptake and heart rate were practically identical (sd 3.1% and 3 beats/minute, respectively) in the experiments. The heavier the work was and the shorter the work time the higher became the pulmonary ventilation. There was a more rapid increase in the functions studied when the heaviest work loads were performed. It is concluded that aerobic capacity can be measured in a work test of from a few up to about 8 min duration, severity of work determining the actual work time necessary. Duration of work in studies of circulation and respiration during submaximal work should exceed 5 min. Submitted on June 23, 1961

scholarly journals Calculating the work of breathing during mechanical ventilation.

2021 ◽  
Vol 2 (2) ◽  
pp. 71-72
Author(s):  
Mia Shokry ◽  
Melina Simonpietri ◽  
Kimiyo Yamasaki
Keyword(s):  
Tidal Volume ◽  
Chest Wall ◽  
Work Of Breathing ◽  
Esophageal Pressure ◽  
Campbell Diagram ◽  
Chest Wall Compliance ◽  
Wall Compliance ◽  
Left Figure ◽  
Inspiratory Work ◽  
Axis Versus

Left figure: Passive patient esophageal pressure (Pes) in cmH2O on x-axis versus tidal volume in ml on y-axis. Green dashed line represents the chest wall compliance Right figure: same patient actively breathing on pressure support ventilation. (Pes) in cmH2O on x-axis versus tidal volume in ml on y-axis. Green dashed line represents the chest wall compliance. Red shaded area is the Campbell diagram representing the inspiratory work of breathing

scholarly journals Mechanical Analysis of Spontaneous Breathing in the Semi-Aquatic Turtle, Pseudemys Scripta

1986 ◽  
Vol 125 (1) ◽  
pp. 157-171 ◽  
Author(s):  
Timothy Z. Vitalis ◽  
William K. Milsom
Keyword(s):  
Tidal Volume ◽  
Breathing Pattern ◽  
Work Of Breathing ◽  
Pulmonary Ventilation ◽  
Periodic Breathing ◽  
Adaptive Strategy ◽  
Breath Holding ◽  
Breath Hold ◽  
Breathing Frequency ◽  
Pseudemys Scripta

The normal breathing pattern of Pseudemys scripta (Schoepff) consists of a continuous burst of breaths separated by a variable period of breath holding. Under normoxic conditions, tidal volume was 6.9 ml kg−1 and the number of breaths was 1.9 min−1. Increases in pulmonary ventilation upon stimulation by hypercapnia (3% CO2) or hypoxia (4% O2) are caused primarily by increases in the number of breaths per minute due to a shortening of the breath-hold period. Tidal volume and breath duration remain unchanged. The instantaneous breathing frequency (f' = 60/Ttot) of 35 ± 2min−1 corresponds to continuous pump frequencies that minimize the rate of the mechanical work of breathing in anaesthetized turtles. This indicates that turtles breathe at a combination of tidal volume and f' that minimizes the power required to ventilate the lungs. To increase ventilation, the breath hold is shortened and more breaths are taken at this optimal combination. Bilateral vagotomy drastically alters the breathing pattern, producing an elevation in tidal volume, a slowing of breathing frequency, and a prolongation of breath duration while total ventilation remains unchanged. These data suggest that periodic breathing in this species may represent an adaptive strategy which is under vagal control and which serves to minimize the cost of breathing.

Maximal oxygen uptake and heart rate in various types of muscular activity

1961 ◽  
Vol 16 (6) ◽  
pp. 977-981 ◽  
Author(s):  
Per-Olof 0Åstrand ◽  
Bengt Saltin
Keyword(s):  
Heart Rate ◽  
Oxygen Uptake ◽  
Supine Position ◽  
Maximal Oxygen Uptake ◽  
Muscular Activity ◽  
Bicycle Ergometer ◽  
Maximal Heart Rate ◽  
Similar Reduction ◽  
Trained Subjects ◽  
Arm Work

Seven subjects performed maximal work of various types. The following exercises were studied: a) cycling a bicycle ergometer in a sitting and b) supine position, c) simultaneous arm and leg work on bicycle ergometers, d) running on a treadmill, e) skiing, f) swimming, and g) arm work (cranking). Vo2 was a few per cent higher in running uphill than in cycling ( a), cranking plus cycling ( c), and skiing, in which events similar values were attained. Heart rate was similar in those types of exercise mentioned ( a, c, d, e). Supine cycling ( b) gave a maximal Vo2 that was about 15% lower than in sitting cycling. A similar reduction in maximal Vo2 was noted in swimming. Maximal work with the arms ( g) gave an oxygen uptake that was about 70% of maximal Vo2 when cycling ( a). It is concluded that the aerobic capacity and maximal heart rate are the same in maximal running or cycling, at least in well-trained subjects. Submitted on June 23, 1961

Oxygen uptake, acid-base status, and performance with varied inspired oxygen fractions

1980 ◽  
Vol 49 (5) ◽  
pp. 863-868 ◽  
Author(s):  
R. P. Adams ◽  
H. G. Welch
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Uptake ◽  
Bicycle Ergometer ◽  
Carbon Dioxide Tension ◽  
Limiting Factor ◽  
Vo2 Max ◽  
And Performance ◽  
Lactate Levels ◽  
Performance Times ◽  
Inspired Oxygen

Six subjects rode a bicycle ergometer on three occasions breathing 17, 21, or 60% oxygen. In addition to rest and recovery periods, each subject worked for 10 min at 55% of maximal oxygen uptake (VO2 max) and then to exhaustion at approximately 90% VO2 max. Performance time, inspired and expired gas fractions, ventilation, and arterialized venous oxygen tension (PO2), carbon dioxide tension (PCO2), lactate, and pH were measured. VO2, carbon dioxide output, [H+]a, and [HCO3-]a were calculated. Performance times were longer in hyperoxia than in normoxia or hypoxia. However, VO2 was not different at exhaustion in normoxia compared with hypoxia or hyperoxia. During exercise, hypoxia was associated with increased lactate levels and decreased [H+]a, PCO2, and [HCO3-]a. The opposite trends were generally associated with hyperoxia. At exhaustion, [H+]a was not different under any inspired oxygen fraction. These results support the contention that oxygen is not limiting for exercise of this intensity and duration. The results also suggest that [H+] is a possible limiting factor and that the effect of oxygen on performance is perhaps related to control of [H+].

Comparison of maximal oxygen uptake values determined by predicted and actual methods

1965 ◽  
Vol 20 (3) ◽  
pp. 509-513 ◽  
Author(s):  
R. G. Glassford ◽  
G. H. Y. Baycroft ◽  
A. W. Sedgwick ◽  
R. B. J. Macnab
Keyword(s):  
Heart Rate ◽  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Correlation Coefficients ◽  
Bicycle Ergometer ◽  
Exercise Heart Rate ◽  
Indirect Test ◽  
Physical Fitness Test ◽  
Mean Values ◽  
Fitness Test

Twenty-four male subjects aged 17–33 were given three direct tests of maximal oxygen uptake and one indirect test. The direct tests were those of Mitchell, Sproule, and Chapman (treadmill); Taylor, Buskirk, and Henschel (treadmill); and Åstrand (bicycle ergometer). The indirect test was the Åstrand-Ryhming nomogram (bicycle ergometer) employing heart rate response to submaximal work. In addition, the Johnson, Brouha, and Darling physical fitness test was administered. The two treadmill tests and the indirect test yielded significantly higher mean values than did the direct bicycle test. However no other significant differences in mean values occurred. Correlation coefficients between the various oxygen uptake tests as well as the fitness test were all found to be significant (.62–.83), i.e., greater than zero. No correlation obtained proved to be significantly greater than any other. The results indicate that direct treadmill tests, employing greater muscle mass, yield higher maximal oxygen uptake values (8%) than does the direct bicycle ergometer test. The Åstrand-Ryhming nomogram appears to produce a good estimation of maximal oxygen uptake, in a population unaccustomed to cycling. erobic capacity; exercise; heart rate Submitted on September 17, 1964

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