Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS AND METHOD FOR TRAINING
OF THE RESPIRATORY MUSCLES
The present invention relates generally to
exercise apparatus. More particularly, the present
invention relates to the exercising or training of the
respiratory muscles.
Recent research has demonstrated that
systematic training of the respiratory muscles can
substantially increase a person's ability to sustain
high levels of lung ventilation and, more importantly,
may enhance a person's endurance when performing sub-
maximal exercise. See U. Houtellier and P. Piwko, ~~The
Respiratory System as an Exercise Limiting Factor in
Normal Sedentary Subjects," Eur. J. Appl. Physiol. 64:
145-152, 1992.
U.S. patents 4,854,574 and 4,981,295 propose
respiratory training devices which impose increased
breathing resistance for strength training of the
respiratory muscles. However, the experimental findings
reported in D. Leith and M. Bradley, ~~Ventilatory Muscle
Strength and Endurance Training," J. Appl. Physiol. 41:
508-516, 1976, indicate that maximal voluntary
ventilation is not enhanced by respiratory muscle
strength training but rather by respiratory muscle
endurance training. Accordingly, it is our
understanding that the flow resistance of the Boutellier
and Piwko breathing device was kept as low as possible
by keeping the diameters of the airway tubing large.
The Leith and Bradley article was not directed
to the question of changes in whole body exercise
endurance as a result of respiratory muscle training.
This article indicates that the exercise capacity of fit
individuals is generally not thought to be limited by
ventilatory muscle endurance.
Using a breathing device (described
hereinafter) for training respiratory muscle endurance,
the Houtellier and Piwko article discusses testing
wherein volunteers were subjected to respiratory muscle
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training (RN1T) for 30 minutes per day for four weeks.
During the RMT, the subjects in Boutellier's and Piwko's
study breathed with breaths that were set at about 60%
of the individual's vital capacity and the breathing
frequencies were, at the beginning of the training
period, about 38 breaths per minute. The tidal volumes
were recorded by a pneumotachograph and a display of
light signals on an array of light emitting diodes. The
subjects watched the display and controlled the depth of
each breath so that it matched upper and lower limits
for inspiration and expiration which were also displayed
as light signals. The desired breathing frequency was
set on a metronome to which the subject had to adjust
his/her breathing frequency. Each week the frequency
was increased by one breath per minute. It was also
understood that, alternatively, incremental changes in
breath volume can be used. In order to counteract the
effects of hyperventilation such as dizziness, which is
due to excessive carbon dioxide elimination
(hypocapnia), carbon dioxide was added to the inhaled
air. By means of gas-analyzing equipment and a control
valve, a physiologically acceptable carbon dioxide level
was maintained in the lung air.
The effect of the RMT described above was
recorded by measuring the subjects' respiratory
endurance at a ventilatory level that, before training,
was sustainable only for about 4 minutes. After the
training, the subjects were able to perform the same
level of ventilation for, on the average, 15 minutes.
Furthermore, the subjects' endurance time when
performing exercise on a cycle ergometer at an intensity
corresponding to 64% of their respective maximal oxygen-
uptake levels was tested before and after RMT. Before
the RNff, the endurance time was typically 27 minutes in
sedentary subjects, and, after RMT, it was increased by,
on the average, between about 24% and 50%. Similar
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effects of RMT have also been observed in athletes,
ranging in proficiency from the amateur to the
professional level. See U. Boutellier, R. Huchel, A.
Kundert, and C. Spengler, "The Respiratory System as an
Exercise Limiting Factor in Normal Trained Subjects,"
Eur. J. Appl. Physiol. 65: 347-353, 1992. These
observations indicate that respiratory muscle fatigue is
performance limiting in healthy individuals performing
sub-maximal exercise. It has furthermore recently been
noted by others that the gains in sub-maximal exercise
endurance obtained by RMT apply also to other types of
physical activity than cycling, such as running, cross-
country skiing, and rowing.
The Leith and Bradley article discloses a
partial rebreathing system wherein subjects rebreathe on
a large dead space tube using mouthpieces. At the
mouthpiece, fresh gas is admitted from a rotameter and
needle valve. A triple-J valve is attached distally of
the dead space tube. A 7-liter bag on the J-valve's
inlet serves as a reservoir and ventilatory target,
i.e., air is admitted to it from a large rotameter, and
subjects are required to keep it nearly empty. The two
rotameters are set to presumably keep end-expired oxygen
and carbon dioxide levels near normal values. Actual
total ventilation is calculated as the target flow plus
half the fresh gas flow since, during expiration, the
latter half of the fresh gas flow is "thrown away"
through an outlet from the J-valve. This apparatus
undesirably requires a fan or compressed air source for
admitting air to the bag and requires calibration of the
large rotameter for setting the breathing target.
Furthermore, dead space can cause dangerous
oxygen lack (hypoxia) and carbon dioxide accumulation
(hypercapnia). The collector bag described in U.S.
patent 5,154,167 may also cause hypoxia and hypercapnia
if the bag volume selected is too large relative to the
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size of the user's breath. The incorporation of
equipment for monitoring the composition of breathing
gas is suggested in U.S. patents 4,301,810 and
5,154,167. However, this equipment typically is costly,
bulky, and requires frequent calibration to be reliable.
U.S. patent 5,154,167 discloses a lung and
chest exerciser wherein some of the air expired from the
lungs is collected in a collector bag to be breathed
back into the lungs on the next inbreath together with
some fresh air through what is called a valve which
consists of filter material held in place by a washer
which fits behind lugs. It is further stated that, with
a double thickness of filter material, the air
resistance is such that on an inbreath all the air in
the collector bag is breathed in before air is drawn
through the filter. It is further disclosed that a
slider may be used on the collector bag to alter the
useable volume quickly and that a counting mechanism
could be fitted to count the number of breaths.
An oxygen mask having a rebreather bag and an
oxygen supply is disclosed in "Flight Surgeon's Guide,"
Air Force Pamphlet AFP 161-18, Department of the Air
Force, Dec. 27, 1968. This oxygen mask is similarly
equipped with sponge-rubber discs, which are said to
serve as valves, through which the latter portion of the
exhaled air is blown off. They are also said to serve
as inspiratory ports for the entrance of ambient air
when inspiration is not fully satisfied by the contents
of the re-breather bag and the flow of oxygen from the
regulator.
None of the above references discloses a
practical apparatus for training for increasing
endurance, which requires breathing speed as well as
volume to be maintained over a period of time.
It is accordingly an object of the present
invention to provide reliable, practical, and
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inexpensive respiratory muscle training apparatus for
increasing endurance.
It is a further object of the present
invention to provide such apparatus which does not
expose the exerciser or trainee to physiologically
unacceptable hypoxia and/or hypercapnia or hypocapnia.
In order to achieve the above objects, in
accordance with the present invention an exerciser (a
person training his or her respiration muscles) inspires
from and expires to a bag which is inflatable for
receiving a predetermined volume of expired air. A
valve is provided to open in response to deflation of
the bag to admit fresh air to the air way. The valve is
closed during the flow of expired air into the bag. The
breathing frequency is paced so that, in combination
with the predetermined volume, the overall ventilation
may be maintained over a period of time for increasing
endurance. As endurance is increased over time, the bag
may be replaced with incrementally larger volume bags or
the bag volume may be incrementally increased.
The above and other objects, features, and
advantages of the present invention will be apparent in
the following detailed description of the preferred
embodiments thereof when read in conjunction with the
accompanying drawings wherein like reference numerals
denote the same or similar parts throughout the several
views.
Brief Description of the Drawings
Fig. 1 is a diagrammatic view illustrating
apparatus which embodies the present invention.
Fig. 1B is a diagrammatic view illustrating a
mouth piece for use alternatively to the oro-nasal mask
illustrated for the apparatus in Fig. 1.
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Fig. 2A is a sectional view of the apparatus
taken along lines 2A-2A of Fig. 1 without the
rebreathing bag therefor being shown.
Fig. 2H is a partially sectional view thereof
taken along lines 2B-2B of Fig. 2A.
Fig. 2C is a sectional view thereof taken
along lines 2C-2C of Fig. 2B.
Fig. 2D is a partial view similar to that of
Fig. 1 illustrating an alternative embodiment of the
present invention.
Fig. 3 is a graph of pressure within the air
way of the apparatus during a period of inspiration and
expiration.
Fig. 4 is a block diagram illustrating
monitoring, processing, and pacing for the apparatus.
Fig. 5 is a diagram illustrating a computer
display therefor.
Fig. 6 is a diagram illustrating a
computer/monitoring device therefor.
Fig. 7 is a plan view of a card for
determining bag volume.
Figs. S, 9, and 10 are diagrammatic views
illustrating various means for adjusting bag volume.
Fig. 11 is a diagrammatic view of an
alternative embodiment of a breathing bag.
Detailed Description of the Preferred Embodiment
Referring to Fig. 1, there is illustrated
generally at 50 apparatus for exercising or training a
person's respiratory system by the exerciser voluntarily
performing a lung ventilation that considerably exceeds
the metabolic demands, i.e., a ventilation that is both
deeper and more rapid than normal resting ventilation.
The apparatus utilizes partial rebreathing of expired
gas (air) from a bag, illustrated at 6A, in order to
avoid hypocapnia due to hyperventilation.
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The apparatus 50 includes an L-shaped or other
suitable tube 1 one end of which is suitably fitted with
an oro-nasal mask 3 for communicating a flow of air
between the tube 1 and the person's respiratory system.
Alternatively, the tube may be fitted with a mouth
piece, illustrated at 2 in Fig. 1B, or other suitable
device for flowing air between the tube 1 and the
person's respiratory system.
The other end of the tube 1 is connected to
the bag 6A, which is suitably made of flexible gas-tight
material such as plastic film so that it is inflatable
and deflatable. Air may thus be inspired from the bag
6A or expired thereto along the flow path provided by
tube 1. The thickness and other properties of the bag
material as well as the tube diameter are chosen in
accordance with principles commonly known to those of
ordinary skill in the art to which this invention
pertains so as to minimize breathing resistance, i.e.,
so that the pressure required to rapidly inflate and
deflate the bag 6A is minimal. Thus, it is considered
desirable that this pressure not exceed about plus and
minus 2 cm. water for inflation and deflation
respectively of the bag. The mouth 51 of the bag 6A may
be sized to be stretched over the end of tube 1 or
alternatively provided with a fitting or other suitable
means for gas-tight attachment to the tube 1.
A valve assembly 5 is suitably gas-tightly
fitted in an opening, illustrated at 4, in the tube 1.
Referring to Figs. 2A, 2B, and 2C, the valve assembly 5
includes a housing 7 in which is contained a valve body
or element 8 composed of a rectangular sheet of
phosphorbronze or other suitable plastic material having
the ability to flex. The housing 7 includes a pair of
side walls 52 and 53, a pair of end walls 54 and 55, and
an upper wall 56. The side and end walls extend through
opening 4 and gas-tightly engage the corresponding sides
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of opening 4. The housing 7 does not include a lower
wall thereby leaving an opening, illustrated at 57, for
flow of air between the tube 1 and the interior of valve
housing 7. The housing 7 includes a member 62 suitably
attached to or integral with the lower interior surface
of end wall 54 to provide a ledge upon which one end 9
of the valve body 8 is laid and fastened thereto by a
pair of screws 58 or by other suitable means such as
rivets, glue, or a tongue-in-groove arrangement. The
valve body 8 is suitably sized so that its three free
edges 59, 60, and 61 are closely adjacent corresponding
walls 52, 53, and 55 respectively without touching them.
This allows the valve body 8 to freely flex for vertical
movement of edge 61 along wall 55 but with minimized
leakage of air between the free edges and the
corresponding walls. The wall 55 is shaped to have a
curved or concave contour, illustrated at 10, for
retaining the close fit between free edge 61 and wall 55
as the valve body 8 flexes for movement of free end 61
upwardly and downwardly. An opening, illustrated at 13,
is provided in the upper portion of end wall 55, and the
contour 10 ends at the opening 13. Thus, the valve 5 is
closed when the valve body 8 is positioned with its free
edge 61 in closely fitting relationship with contoured
surface 10 so as to substantially prevent flow of air to
or from the tube 1. Flexing of the valve body 8 so that
its free end 61 rises above the contoured surface at 11
or drops below the contoured surface at 12 opens the
valve 5 to the flow of air into or out of tube 1 through
the interior of housing 7 and through the opening 13.
The sizing and choice of materials for the
valve 5 are selected, in accordance with principles
commonly known to those of ordinary skill in the art to
which this invention pertains, so that the positive or
negative gas pressure required to flex the valve body 8
to open the valve 5 will allow full inflation and
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deflation of the bag 6A on expiration and inspiration
respectively before gas (air) flow occurs through the
valve 5 out of and into the tube 1. Thus, upon
expiration into bag 6A, the pressure within the flow
path through tube 1 is insufficient to open the valve 5
until substantially full inflation of the bag 6A has
occurred, after which excess expired air is released
through the valve 5 when the valve body 8 is flexed for
movement of free edge 61 upwardly beyond the contoured
surface 10. Upon inspiration, substantially all of the
air in bag 6A is inspired with the valve 5 closed, after
which the pressure drop caused by continued inspiration
causes the valve body to be flexed for movement of the
free edge 61 downwardly beyond the contoured surface 10
to open the valve 5 thereby admitting fresh air to the
flow path within tube 1. The inflation and deflation
pressures of the bag 6A should, at its mouth 51, be
desirably no more than plus and minus 2 cm. water
respectively.
The present invention is not limited to the
type of valve described above. For example, the valve
may alternatively be a spring-loaded disc valve. For
another example, as discussed hereinafter with reference
to Fig. 2D, a two-valve arrangement may be provided
wherein one spring-loaded valve 5a opens during
inspiration and the other spring-loaded valve 5b opens
during expiration.
Referring to Fig. 1, the exercise apparatus 50
includes a sensor, illustrated at 16, suitably connected
to the tube 1 to sense changes in the air flow path.
The sensor 16 is suitably connected to a computing unit
15, which is shown in Fig. 1 to be suitably mounted to
the tube 1 so that its screen, illustrated at 19 in Fig.
5, is viewable by the exerciser, to determine the
exerciser's breathing frequency. The sensor 16 may
suitably be of a type to sense pressure, temperature, or
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flow rate changes within the tube 1 or changes in gas
composition or humidity or other conditions within the
tube. Sensor 16 may, for example, be a pressure
transducer placed in the wall of the breathing tube 1
adjacent to bag 6A. Transducer 16 generates a signal
which is graphically depicted at 86 in Fig. 3. Section
AB of this graph represents the expiration filling bag
6A. When the bag is full, the pressure rises slightly
(BC) as valve 5 is deflected and opens. Section CD
represents the time that valve 5 stays open. Section DE
represents the closing of valve 5 and the beginning of
the inhalation of the gas from bag 6A, which lasts
during section EF. Section FG represents opening of the
valve and the beginning of inhalation of fresh air.
Section GH represents the duration of the inhalation.
Section HA' represents closing of the valve and the
beginning of the next expiration into the bag.
The monitoring of the alveolar ventilation
depends on determining the gas flow as the predetermined
or known volume of gas (air) in the fully inflated bag
6A is inhaled and by measurement of the duration (AB) of
this inspiration. By also recording the time (BD) that
the fresh air is inhaled, the volume of fresh air in the
breath (VFA) can be adequately calculated based on the
assumption that gas flow remains essentially constant
during the inhalation. This is considered to be an
acceptable assumption given the high ventilation rates
used for RMT. The fresh air volume supplies the dead
space in the apparatus (VDT,), the dead space of the
lungs and airways (VD,L), and the portion of the breath
that reaches the alveoli (VA). Thus,
__ VD~,,, t VD~L + VA,
where VDT is fixed by the design of the apparatus and VD,L
is known from standard texts in respiratory physiology.
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By multiplying VA by the average measured breathing
frequency, a representative value for the alveolar
ventilation (V'A) is obtained. This V'A is averaged over
a suitable number of breaths.
The known volume of bag 6A divided by the
duration of section EF (Fig. 3) yields the average gas
flow rate of inspiration. It is reasonable to assume
that, with the high levels of ventilation used for RMT,
the inspiratory flow rate is essentially constant.
Hence, this calculated average gas flow rate multiplied
by the time interval GH will yield the volume of fresh
air inhaled in the breath (VFA). By subtracting the
predetermined values for VD,L and VDT,, the VA of this
breath is obtained. The average V',, is calculated by
summing the V~ for a suitable number of breaths, for
example, ten, and dividing this sum by the summed
durations of these breaths. This V'A is then compared
with the programmed target ventilation. If the V'A
deviates more than, for example, 20%, the display unit
15 has a signal, illustrated at 79 in Fig. 5, to notify
the exerciser to take deeper breaths in case he/she has
undershot the target and a signal 78 to notify the
exerciser to take more shallow breaths if the target has
been overshot. The warning signals 78 and 79 may have
different acoustic and/or optical characteristics. For
example, such alarms may be embodied as light emitting
diodes, as shown, or buzzers or both. It can be seen
that, alternatively, expiratory phase recordings of gas
flow may be used for determining V'A since the
inspiratory and expiratory flows may be considered to be
essentially equal for these purposes. The opening and
closing of valve (5) may alternatively be recorded, for
example, by signals from strain gauges attached to the
valve body 8, optically by photocells in the valve
housing 7, by a meter sensing the flow in tube 1 or
through the valve 5, or by other suitable means.
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Referring to Fig. 2D, there is illustrated at
63 an alternative embodiment of the exercise apparatus
wherein two valves 5a and 5b are connected to the tube
1. Valve 5a is provided to open during inspiration
after the bag 6A is substantially fully deflated to draw
fresh air into the air flow path way in the tube 1.
Valve 5b is provided to open during expiration after the
bag 6A is substantially fully inflated to release excess
expired air. Otherwise, the valves 5a and 5b are
closed.
A short piece of tubing or hose 64 is suitably
attached to the exhaust side of valve 5b and has a
suitable volume of, for example, 20 ml. to serve as a
reservoir of expired gas. A meter or sensor,
illustrated at 65, which is described hereinafter, is
placed within the hose 64. Overventilation will
manifest itself by an abnormally high oxygen
concentration and, by necessity, an abnormally low
carbon dioxide concentration in the expired gas, and
underventilation will lead to the opposite condition.
Thus, overventilation or underventilation may be
determined by measuring oxygen concentration in the
expired gas. Accordingly, if desired, the meter 65 is
selected to be an oxygen sensor, which is suitably
placed within the tubing 64 to measure and record oxygen
partial pressure in the reservoir of expired gas. The
oxygen sensor may, for example, be a fuel cell or a
paramagnetic oxygen sensor. The expired gas reservoir
allows the oxygen meter 65, which may be relatively
slowly acting, to analyze the expired gas during the
expiration phase of a breath and during the inspiration
phase of the following breath. The oxygen meter 65 is
desirably positioned inside the hose 64 as close to the
expiration valve 5b as possible to thus measure the
oxygen in the alveolar portion of the expired gas. The
output from the oxygen meter 65 is fed to the computing
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unit 15 which is suitably programmed to compare the
output with predetermined minimally and maximally
acceptable limits. Such limits can be set at, for
example, a low oxygen pressure of 90 mm of mercury and a
high value of 110 mm of mercury. The corresponding
carbon dioxide pressures will, assuming a reasonably
normal respiratory quotient, not expose the exerciser to
dangerous or unduly unpleasant hyper- or hypocapnia.
Moreover, the minimally acceptable oxygen limit ensures
that the exerciser will not be exposed to undue hypoxia.
An alarm (not shown) may be provided to give a warning
in the event of deviations from these predetermined
limits, thus alerting the exerciser to the need for an
altered breathing pattern.
Alternatively, meter 65 may be selected to be
a carbon dioxide meter (or a sampling port for a carbon
dioxide meter may be placed in the short piece of tubing
or hose 64) to thus measure the carbon dioxide partial
pressure in the alveolar portion of the expired gas and
thereby assure proper alveolar ventilation. The output
from the carbon dioxide meter is fed to the computing
unit 15 which compares the output with predetermined
minimally and maximally acceptable limits. Such limits
would be chosen so as to prevent undue hyper- or
hypocapnia. They can be set at, for example, a low
carbon dioxide pressure of 30 mm of mercury and a high
value of 50 mm of mercury. The corresponding oxygen
pressures will, assuming a reasonably normal respiratory
quotient, not expose the trainee to dangerous or unduly
unpleasant hypoxia. An alarm and/or light (not shown)
may be provided to provide warning in the event of
deviations from these predetermined limits thus alerting
the exerciser to the need for an altered breathing
pattern. It shall be understood that an oxygen or
carbon dioxide sensor, while it may be desirable, is not
required for practice of the present invention.
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Referring to Fig. 4, the computing unit 15
includes a timing device 17 for indicating elapsed time.
Timing device 17 may, for example, be a crystal
controlled oscillator with a known pulse frequency and a
counter for the number of pulses between breaths. The
number of pulses counted can then be converted to the
equivalent breathing frequency (number of breaths per
minute) by a processing device 18. The breathing
frequency may then be stored in memory of computing unit
15 and displayed. The mean breathing frequency,
displayed as illustrated at 89, over, for example, five
breaths is calculated from the stored values and
displayed at 70 on display 19. Actual frequency display
70 contains increments of mean breathing frequency from,
for example, 24 to 40 breaths per minute. The exerciser
can select a desired target breathing frequency, as
illustrated at 85, e.g., by using a keyboard 20 (which
may comprise push buttons on the display 19), which is
then shown in display 19. Thus, the exerciser is paced
for the desired frequency, as set at 87, by the display
at 70 of the actual frequency, i.e., the actual
frequency display 70 provides feedback to the exerciser
so that he or she may be paced to slow down or speed up
his or her breathing so that the actual frequency at 70
matches the set frequency at 87.
An individual breath pacing signal is suitably
calculated by processing device 18 based on the set
breathing frequency 87 and displayed as illustrated at
66 by a series of light emitting diodes which are
successively lighted from bottom to top for the
calculated duration of inhalation and from top to bottom
for the calculated duration of exhalation. This allows
the exerciser to pace each individual breath so as to
terminate inspiration and exhalation at the times
indicated on display 66. It would also be desirable to
display actual stages of each individual breath to
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provide feedback to the exerciser as to whether he or
she is ahead of or behind the set individual breath
pace. Time from the start of a training session can
also be displayed, as illustrated at 76, and can be
reset by pushing a reset button 88.
The means by which the selected target
breathing frequency, instantaneous and mean breathing
frequencies, pacing signal, and warning signals are
presented to the exerciser thus include, but are not
limited to, optical and acoustical. Computing unit 15
can thus be programmed to alert the exerciser, as
described above, should the exerciser deviate from the
selected breathing frequency for a certain number of
breaths, for example, five breaths, or for a certain
length of time, for example, ten seconds. The computing
unit 15 may also be programmed to store and display
progress information about the individual exerciser.
If desired, the information obtained by
monitoring the breathing of one or more exercisers by
one or more computing units 15 may be transmitted by a
transmitter 22, as illustrated at 95 in Fig. 6, to a
remote monitoring device 23, such as by wire, radio
signal, or light signal (e.g., infrared). The
monitoring device 23 also incorporates a computer which
processes the signals and displays them so as to allow
monitoring of the performance of one or more exercisers.
In addition, the remote monitoring device 23 may have
alarm functions which alert the trainer to deviations
from the training targets selected, as earlier
described, on each trainee's computing unit 15.
Furthermore, like the computing units 15, the remote
monitoring device 23 may have storage functions which
allow data retrieval and processing which can be used
for monitoring of short and long term training progress.
The computing units 15 and monitoring device 23 can be
suitably programmed, including prompting of the user, to
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perform as described herein using principles commonly
known to those of ordinary skill in the art to which
this invention pertains.
Referring to Fig. 7, there is illustrated at
24 a card for use by an exerciser for determining a
suitable bag volume for beginning exercising. The card
24 has printed thereon a vertical scale 25 in
centimeters or feet and inches spanning a normal range
of body heights and another vertical scale 26 in years
spanning a suitable age range representative of the
expected user clientele. Between scales 25 and 26 are
two essentially vertical scales 27 and 28 for vital
capacity and training bag volume respectively, spanning
a range of volumes expressed, for example, in liters.
By conventional practice, a straight line, illustrated
at 96, connecting the exerciser's age and height on
scales 26 and 25 respectively will indicate the normal
vital capacity on scale 27 at its point of intersection
therewith. A suitable bag volume (training volume) to
begin exercising is suitably a percentage of the vital
capacity. The training volume scale 28 reflects this
percentage, which is believed to suitably be about 60%.
Thus, the numbers on scale 28 represent 60% of the
corresponding vital capacity numbers on scale 27. Since
it is known that men and women have somewhat different
relationships between antropormetric data and vital
capacities, separate scales are desirably provided for
males and females.
Alternatively, the information on card 24 may
be entered in either of computing devices 15 or 23 or
other suitable computer programmed to translate an
exerciser's gender, age, and height into a suitable bag
volume for beginning exercising.
Over time as the exerciser's respiratory
muscle endurance increases, he or she should find that
the bag volume which has been used is no longer adequate
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for effective training and that a larger volume bag is
needed. Referring again to Fig. 1, in accordance with
the present invention, the exercise apparatus 50 is
provided with a plurality of bags 6B and &C in addition
to 6A each of which is inflatable for receiving a
different predetermined quantity of expired air. The
bags 6A, 5B, and 6C may have their fully inflated volume
capacities printed thereon, as illustrated at 80. Thus,
when a bag such as bag 6C becomes too small for the
exerciser, it may be easily and quickly replaced with
the next size larger bag, for example, bag 6A. The set
of bags may desirably comprise a series of bags with
preselected maximal volumes ranging, for example, from
perhaps about 1.5 to 8 liters in perhaps roughly 15%
increments.
Alternatively, a single bag may be convertible
to different maximal volumes. Referring to Figs. 8, 9,
and 10, there are illustrated generally at 80, 90, and
100 respectively bags having such convertibility. Thue,
for example, the volume of bag 80 may be adjusted by a
clip 82, limiting inflation and deflation to the upper
part 84 of the bag. For another example, the volume of
bag 90 may be made smaller by pushing stepped plastic
°zip-lock" style holders 92 or the like together. For
another example, the bottom 102 of the bag 100 may be
rolled up and secured by clamp 104 to reduce its volume.
Thus, it is apparent that various suitable means may be
provided for adjusting volume of a bag.
Referring to Fig. 11, a bag 110, which may be
similar to bag 6A, may, if desired, alternatively have a
short tube 112 to which it is intended that bag 110
remain attached and which is suitably attachable to tube
1.
Bag 110, when filled with air, is seen to take
on the shape generally of a cylinder with a generally
constant diameter throughout substantially its height.
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The bottom end 114 may suitably be sealed by gluing or
heating to form a straight seam, and the other end is
narrowed to neck 51 to allow a tight fit around one end
of tube 112. Although the maximum volume of bag 110 is
desirably about 8 liters, it may be leas as long as it
somewhat exceeds the expected vital capacity of the
exerciser. Hag 110 has printed thereon over its height
scales 116 and 118 labeled vital capacity and training
volume respectively for the purposes of aiding the
exerciser to determine the appropriate training volume
for him or her, without resort to the card 24 or the
need to input age and height information to a computer.
The use of the bag 110 also allows the exerciser to more
directly and thus more precisely determine training
volume without the need to rely on age and height for
standard approximations thereof. The vital capacity
scale 116 has volume gradations in, for example, liters
with, for example, 0.5 liter increments, with lower
numbers towards neck 51. The training volume scale 118
is parallel to vital capacity scale 116 and has volume
gradations which are 60% (or other suitable percentage)
of the vital capacity markings. The vital capacity
markings are connected to the corresponding training
volume markings by lines, illustrated at 120, printed on
the bag 110.
In order to utilize bag 110, the tube 112
should be detached from tube 1, and the bag 110 should
be empty. The exerciser should inhale maximally, put
the tube 112 in his or her mouth, and exhale as deeply
as possible into the bag 110. While holding his or her
breath briefly without letting air out of the bag 110,
the exerciser should then close off the neck 51 using a
suitable means such as, for example, a pressure seal if
the bag is so equipped or a clamp. The bag 110 should
then be placed on a flat surface and compressed such as
by rolling it tightly from its lower end 114 until the
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remaining or unrolled portion of the bag is well filled,
similarly as illustrated for bag 100 in Fig. 10. The
exerciser's vital capacity may then be read from scale
116 at the level where the compressed (rolled up) part
of the bag ends and its inflated portion begins. The
bag 110 may then be emptied, and the training volume
selected by following the corresponding diagonal line
120 from the exerciser's vital capacity marking 116,
just determined, to the scale 118 where the matching
training volume may be read. The bag volume may then be
adjusted at this training volume level using means such
as illustrated in any of Figs. 8, 9, and 10, or a bag
having the matching training volume may be selected and
substituted therefor, in accordance with Fig. 1.
Alternatively, the exerciser can determine
his/her vital capacity by attaching empty bags of
varying volumes to breathing tube 1. Referring to Figs.
2A and 2B, opening 13 is then sealed off with a finger,
and a full breath is taken in and blown into the bag
until no more air can be breathed out. If, when the bag
is full, the user can still exhale more, the next larger
bag is tried until one is found that the exerciser can
just barely fill. The vital capacity corresponds to the
volume printed on this bag. If in the first breath the
chosen bag cannot be filled, stepwise smaller bags are
tried. Once the vital capacity has been determined, the
recommended training volume corresponding to that vital
capacity can be found by use, as earlier described, of
scales 27 and 28 on volume card 24 or by calculating 60%
of the vital capacity. The bag with a volume closest to
that training volume is then connected to tube 1 and
used for the RMT.
Referring to Fig. 5, to begin exercising,
buttons 20 are pushed to set the desired pacing
frequency of breaths per minute on scale 87, and the
training-bag volume is also entered on computing unit 15
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as illustrated at 68. The exerciser then puts mouth
piece 2 in the mouth and preferably dons a nose clip to
prevent undue air flow through the nose. Alternatively,
the oro-nasal mask 3 is used in which case no nose clip
is needed. The exerciser then attempts to breathe at
the frequency indicated by the individual breath pacing
display 66 on computing unit 15. If the exerciser's
displayed actual breathing frequency at 70, which is the
moving average of, for example, 5 breaths, does not
match that set on the set frequency display 87, the
exerciser should notice and adjust his or her
respiration rate up or down as needed to match the
desired frequency 87. If the breathing frequency of the
exerciser deviates for more than, for example, 5 seconds
by more than, for example, 3 breaths per minute from the
preset rate 87, the appropriate (speed up or slow down)
optical warning light 72 is lit and/or an acoustic
signal will sound until a cancel button 74 is pushed or
until the breathing frequency is corrected.
Each expiration will fill bag 6A with alveolar
air which has a higher carbon dioxide content and lower
oxygen content than fresh air. Once bag 6A is full, the
air pressure in tube 1 will rise slightly so as to
exceed the opening pressure of valve 5 which will cause
valve 5 to open to expel the remainder of the expired
air. The first part of the following inspiration will
consist of the carbon dioxide-rich gas from the
preceding expiration which was stored in bag 6A, and,
when bag 6A is emptied, the air pressure in tube 1 will
fall so as to open the valve 5 and allow fresh air to be
inhaled therethrough. The depth of the inspiration
should normally be adjusted by the physiologic control
mechanisms of the body which serve to ensure an adequate
carbon dioxide and oxygen exchange. The deep and rapid
breathing induced by the device should ensure the
desired RMT, and this exercise may be continued for, for
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example, 30 minutes per training session as guided by
timing device 17 in the computing unit 15 and displayed
as illustrated at 76.
In accordance with the findings discussed in
the previously discussed Boutellier and Piwko and
Boutellier et al articles, the breathing frequency
should initially be selected at between 40 and 50
breaths per minute. In subsequent training sessions,
the preselected breathing frequency and/or the
preselected rebreathing volume are increased in small
increments so as to push the exerciser's lung
ventilation to ever increasing levels that are just
barely sustainable for 30 minutes. These adjustments
may be modified by trial and error. Thus, if the
exerciser becomes exhausted by a certain combination
before the 30 minute training session is finished, the
frequency and/or training bag volume is reduced stepwise
until sustainable for a full 30 min. It is believed
that, ideally, the 30 minute training sessions should be
performed once daily, 5 days a week, and for 4 weeks in
order to obtain a good enhancement of sub- maximal
exercise endurance as demonstrated by the previously
discussed Boutellier and Piwko and the Boutellier et al
articles. It is of course understood that future
research may result in further optimization of the
training schedules described above.
It is known from the physiological literature
that occasionally even healthy persons may hyper- or
hypoventilate, i.e. breathe more or less than is called
for by the metabolism. Such deviations from normal
breathing patterns may be due to, for example,
nervousness in the case of hyperventilation or an
automatic reduction of the breathing whenever the
subject breathes on a breathing apparatus (so called COZ
retainers). Such deviations may cause unpleasant
sensations such as dizziness, headaches, or, in the case
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of hypoventilation, even dangerous hypoxia. Should the
exerciser experience hyperventilation and thus
hypocapnia by taking breaths that are too deep for a
given breathing frequency, the flow throughout the
inhalation will be excessive and thus the calculated V~A
too high. This should trigger the volume warning light,
illustrated at 78, and/or any other alarm and prompt the
exerciser to take smaller breaths. Conversely, if the
exerciser hypoventilates, the inspired gas flow will be
too low and the volume warning light, illustrated at 79,
and/or alarm should go off and prompt the exerciser to
take deeper breaths.
The exercise apparatus of the present
invention thus allows the user to determine his/her
vital capacity and, based on that determination, select
and set, without calculations, the desired rebreathing
volume. Furthermore, the exercise apparatus allows easy
change of the rebreathing volume as may be called for by
changes in the training protocol, i.e., as the
respiratory system endurance improves. The exercise
apparatus also allows the user to select the desired
breathing frequency and enter it into pacing means for
feedback so that the user may be aided in achieving the
desired breathing frequency. Preferably, the pacing
means is programmed to record the breathing frequency
actually performed and presents it optically in the same
format as the desired frequency is entered, as seen at
87 and 70 in Fig. 5, so as to allow the user to easily
compare the two and make necessary adjustments of
his/her breathing frequency. Moreover, in case of
significant deviations from the desired frequency, such
as due to inattentiveness or exhaustion on part of the
trainee, an optical and/or acoustic signaling device in
the electronic monitor is desirably provided to alert
the trainee and/or trainer, if present, to the
situation. Alternatively, the signal is transmitted by
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wire or wireless means to a central receiver which can
conveniently be monitored by a trainer, and the signal
from each trainee may be coded so as to allow the
trainer to identify the trainee. In order to reduce the
risk of dangerous or unpleasant hypoxia, hypercapnia, or
hypocapnia, it should be ensured that the supply of
fresh air to the alveolar space in the lung (alveolar
ventilation) is adequate to sustain, with a safety
margin, an oxygen consumption and carbon dioxide
production (metabolism) corresponding to the needs of
the body at rest. Deviations from this alveolar
ventilation will trigger a light 78 or 79 or an alarm
alerting the user to the need for an altered breathing
pattern.
It should be understood that, while the
invention has been described in detail herein, the
invention can be embodied otherwise without departing
from the principles thereof, and such other embodiments
are meant to come within the scope of the present
invention as defined by the appended claims.
