OPTIMAL EXERCISE INTENSITY ESTIMATION METHOD, TRAINING METHOD, EXERCISE INSTRUCTION DEVICE, AND OPTIMAL EXERCISE INTENSITY ESTIMATION SYSTEM

Abstract

A method for estimating optimal exercise intensity includes: a step to give a ramped load to a subject so as to obtain a value of blood oxygen concentration (SpO.sub.2) at each predetermined different workload, which is measured over a range that overlaps at least a part of 96 to 100%; and a step to determine a starting point of decline at which the measured value of blood oxygen concentration starts to show a declining trend as the workload increases; wherein the workload at the starting point of decline is estimated as an optimal exercise intensity for the subject. The method is capable of indicating a workload for attaining an individual's optimal exercise intensity.

Claims

1. A method for estimating optimal exercise intensity, characterized by comprising: a step to give a ramped load to a subject so as to obtain a value of blood oxygen concentration (SpO.sub.2) at each predetermined different workload, which is measured over a range that overlaps at least a part of 96 to 100%; and a step to determine a starting point of decline at which the measured value of blood oxygen concentration starts to show a declining trend as the workload increases; wherein the workload at the starting point of decline is estimated as an optimal exercise intensity for the subject.

2. The method for estimating optimal exercise intensity according to claim 1, characterized by being a method that measures a pulse rate simultaneously with the SpO.sub.2 and determines the starting point of decline based on change in SpO.sub.2 over time; wherein, once the pulse rate first exceeds a target pulse rate, the value of SpO.sub.2 at a time the pulse rate first exceeded the target pulse rate is used as a reference value, and a measurement point of SpO.sub.2 immediately before a range where the measured value of SpO.sub.2 indicated a value lower than the reference value consecutively for 5 seconds or longer is determined as the starting point of decline.

3. The method for estimating optimal exercise intensity according to claim 1, characterized by being a method that measures a pulse rate simultaneously with the SpO.sub.2 and determines the starting point of decline based on change in SpO.sub.2 over time; wherein, once the pulse rate first exceeds a target pulse rate, the value of SpO.sub.2 at a time the pulse rate first exceeded the target pulse rate is used as a reference value, and a point of intersection between a straight line connecting a measurement point of a highest value and a measurement point of a lowest value, of SpO.sub.2, in a range where the measured value of SpO.sub.2 indicated a value lower than the reference value consecutively for 5 seconds or longer, and an approximate straight line drawn using measurement points of SpO.sub.2 value before the range, is determined as the starting point of decline.

4. A method for estimating optimal exercise intensity, characterized by comprising: a step to give a ramped load to a subject so as to obtain a value of blood oxygen concentration (SpO.sub.2) at each predetermined different workload, which is measured over a range that overlaps at least a part of 96 to 100%, and measure a pulse rate simultaneously with the SpO.sub.2; and a step to determine an inflection point at which a behavior of (SpO.sub.2/pulse rate) changes as the workload increases; wherein the workload at the inflection point is estimated as an optimal exercise intensity for the subject.

5. A training method characterized in that exercise is performed at the optimal exercise intensity estimated by the estimation method according to claim 1.

6. An exercise instruction device characterized by comprising: a storage means for storing biological information values at the optimal exercise intensity estimated by the estimation method according to claim 1; a measurement means capable of measuring the biological information values; a computation means for calculating a workload by comparing the biological information values measured by the measurement means against the biological information values at the optimal exercise intensity; and an instruction means for indicating the workload calculated by the computation means.

7. The exercise instruction device according to claim 6, characterized in that: the measurement means is capable of measuring a blood oxygen concentration (SpO.sub.2); the instruction means is capable of indicating the workload which is a workload used as a ramped load, based on information relating to the biological information values from the measurement means; and the computation means is capable of calculating a starting point of decline at which the measured value of blood oxygen concentration starts to show a declining trend as the workload increases.

8. The exercise instruction device according to claim 6, characterized in that: the measurement means is capable of measuring a blood oxygen concentration (SpO.sub.2) and a pulse rate; the instruction means is capable of indicating the workload which is a workload used as a ramped load, based on information relating to the biological information values from the measurement means; and the computation means is capable of calculating an inflection point at which a behavior of SpO.sub.2/pulse rate changes as the workload increases.

9. The exercise instruction device according to claim 6, characterized by being a wearable terminal.

10. A system for estimating optimal exercise intensity, characterized by comprising: a measurement part that measures a blood oxygen concentration (SpO.sub.2) over a range that overlaps at least a part of 96 to 100%; an instruction part that indicates a workload that is used as a ramped load; and a computation part that calculates a starting point of decline at which the measured value of blood oxygen concentration starts to show a declining trend as the workload increases; wherein the workload at the starting point of decline is estimated as an optimal exercise intensity.

11. A system for estimating optimal exercise intensity, characterized by comprising: A measurement part that measures a blood oxygen concentration (SpO.sub.2) over a range that overlaps at least a part of 96 to 100%, and also simultaneously measures a pulse rate; an instruction part that indicates a workload that is used as a ramped load; and a computation part that calculates an inflection point at which a behavior of (SpO.sub.2/pulse rate) changes as the workload increases; wherein the workload at the inflection point is estimated as an optimal exercise intensity.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIG. 1 A diagram showing how the SpO.sub.2 and pulse rate of subject A changes over time during exercise under a ramped load.

[0048] FIG. 2 A scatter plot of the SpO.sub.2 and pulse rate of subject A during exercise under a ramped load.

[0049] FIG. 3 A scatter plot of the SpO.sub.2 and SpO.sub.2/pulse rate of subject A during exercise under a ramped load.

MODE FOR CARRYING OUT THE INVENTION

Estimation Method and Estimation System

[0050] The first method for estimating optimal exercise intensity proposed by the present invention is characterized in that it comprises: [0051] a step to give a ramped load to a subject so as to obtain a value of blood oxygen concentration (SpO.sub.2) at each different workload, which is measured over a range that overlaps at least a part of 96 to 100%; and [0052] a step to determine a starting point of decline at which the measured value of blood oxygen concentration starts to show a declining trend as the workload increases; [0053] wherein the workload at the starting point of decline is estimated as an optimal exercise intensity for the subject.

[0054] The second method for estimating optimal exercise intensity proposed by the present invention is characterized in that it comprises: [0055] a step to give a ramped load to a subject so as to obtain a value of blood oxygen concentration (SpO.sub.2) at each different workload, which is measured over a range that overlaps at least a part of 96 to 100%, and measure the pulse rate simultaneously with the SpO.sub.2; and [0056] a step to determine an inflection point at which the behavior of SpO.sub.2/pulse rate changes as the workload increases; [0057] wherein the workload at the inflection point is estimated as an optimal exercise intensity for the subject.

[0058] It should be noted that, in the Specification, A to B (A and B are numbers) indicates a range of numerical values including the values of A and B, or specifically A or greater but no greater than B.

[0059] The blood oxygen concentration (SpO.sub.2) is a ratio of binding of the red blood cell hemoglobin and oxygen in arterial blood. SpO.sub.2 can be measured simply by wearing a measuring device (pulse oximeter) at the fingertip, over the wrist, etc. The method for estimating optimal exercise intensity proposed by the present invention is noninvasive and therefore puts minimal burden on the subject.

[0060] The first and second estimation methods have a step to give a ramped load to a subject so as to obtain a value of blood oxygen concentration (SpO.sub.2) at each different workload, which is measured over a range that overlaps at least a part of 96 to 100%.

[0061] The exercise method to give a ramped load is not specifically limited, and a treadmill, bicycle ergometer, stepper, etc., may be adopted.

[0062] The measured value of SpO.sub.2 should fall within a range that overlaps at least a part of 96 to 100%, such as 95 to 100%, 97 to 100%, 98 to 100%, 99 to 100%, 97 to 99%, etc. Decreasing the lower limit of the SpO.sub.2 measuring range allows for more accurate estimation of optimal exercise intensity but increases exercise burden during measurement. For this reason, preferably a lower limit is set for each subject according to his/her sex, age, exercise habits or lack thereof, etc., and measurement is stopped once the measured value of SpO.sub.2 drops below the set lower limit. In particular, lower blood oxygen concentrations (SpO.sub.2) indicate greater burden on the subject, so this lower limit is preferably 95% or higher, or more preferably 96% or higher.

[0063] The SpO.sub.2, etc., can be measured continuously, but since measurement is performed during exercise, the measuring devices may shift and prevent accurate measured values from being obtained. For this reason, preferably measured values obtained from intermittent measurements taken every 0.1 to 5 seconds or so are consolidated into average values over 1 to 30 seconds or so, and used as such. Also, since the workload gradually increases under a ramped load, the biological information values that are measured normally change only in one directionfor example, the SpO.sub.2 changes only in the direction of decreasing, while the pulse rate changes only in the direction of increasingand this allows for employment of, for example, processing that does not use values indicating change in the opposite-to-normal direction, or processing that does not use a value at the measurement point with a rate of deviation of, for example, 10% or greater from the average of values taken at around 2 to 5 points before it.

[0064] The second estimation method measures the pulse rate simultaneously with the SpO.sub.2. It should be noted that the pulse rate can also be measured simultaneously with the SpO.sub.2 under the first estimation method. Furthermore, the first and second estimation methods allow for measurement of one type, or two or more types, of biological information value(s) including the blood pressure, lactate concentration (in blood, in sweat), carbon dioxide concentration in breath gas, and so on. Of these, the pulse rate is preferred for simplicity of measurement.

[0065] Under the first and second estimation methods, preferably measurement is performed within a range of blood oxygen concentrations of 96% or higher and a range of pulse rates of 160 beats/less, so that burden on the subject can be reduced.

[0066] The first estimation method has a step to determine a starting point of decline at which the measured value of SpO.sub.2 starts to show a declining trend as the workload increases.

[0067] The anaerobic threshold (AT) is a point at which aerobic exercise switches to anaerobic exercise, and at the AT oxygen concentration in the body starts to drop due to a lack of oxygen supply needed to continue exercising/producing energy. Accordingly, the starting point of decline at which the measured value of SpO.sub.2 starts to show a declining trend approximates the AT.

[0068] Additionally, the workload at this starting point of decline approximates the workload at the AT, which allows the workload at the starting point of decline to be estimated as an optimal exercise intensity for the subject.

[0069] The second estimation method has a step to determine an inflection point at which the behavior of SpO.sub.2/pulse rate changes as the workload increases.

[0070] As the workload increases, SpO.sub.2 drops and pulse rate increases and therefore the SpO.sub.2/pulse rate shows a dropping trend. That this SpO.sub.2/pulse rate has an inflection point beyond which its slope increases, and that this inflection point approximates the anaerobic threshold (AT), are new insights gained by the inventors of the present invention.

[0071] The first estimation method may be implemented by, for example, a first system for estimating exercise intensity that comprises: [0072] a measurement part that measures the blood oxygen concentration (SpO.sub.2) over a range that overlaps at least a part of 96 to 100%; [0073] an instruction part that indicates a workload that is used as a ramped load; and [0074] a computation part that calculates a starting point of decline at which the measured value of blood oxygen concentration starts to show a declining trend as the workload increases; [0075] wherein the workload at the starting point of decline is estimated as an optimal exercise intensity.

[0076] The second estimation method may be implemented by, for example, a second system for estimating optimal exercise intensity that comprises: [0077] a measurement part that measures blood oxygen concentration (SpO.sub.2) over a range that overlaps at least a part of 96 to 100%, while also simultaneously measures the pulse rate; [0078] an instruction part that indicates a workload that is used as a ramped load; and [0079] a computation part that calculates an inflection point at which the behavior of SpO.sub.2/pulse rate changes as the workload increases; [0080] wherein the workload at the inflection point is estimated as an optimal exercise intensity.

[0081] The first and second estimation systems may also have, besides the above, a storage part that stores the measured values, a communication part that exchanges data externally, and a display part that displays the contents of instructions, for example. Also, the storage part and computation part may be at least partially comprised of a cloud-based system whose processing takes place on an external server with which the estimation system communicates through the communication part. Furthermore, the first and second estimation systems may be a smartphone, smart watch, smart glasses, earpiece, or other wearable device that is made capable of implementing the aforementioned means by installing therein an application having a function to estimate optimal exercise intensity. The first and second estimation systems may be constituted by connecting a pulse oximeter or other measuring device having the instruction part, and a treadmill, bicycle ergometer, or other training machine found in gyms, etc., using a cable or wirelessly, so that while the measurement part (measuring device) measures the user's blood oxygen concentration, the instruction part indicates a speed, incline, resistance, etc., for the exercise machine, such as treadmill or bicycle ergometer, and instructs the user to adjust a workload to be a ramped load.

[0082] The first and second estimation systems obtain the blood oxygen concentration (SpO.sub.2) over a range that overlaps at least a part of 96 to 100%, and the lower limit of the range is preferably 95% or higher, or more preferably 96% or higher. Since the first and second estimation systems measure the SpO.sub.2 over a range that overlaps at least a part of 96 to 100%, where a preferred lower limit is 95% or higher, burden on the subject during measurement can be reduced. Also, the first and second estimation systems may be constituted by combining a pulse oximeter or other measuring device capable of measuring the blood oxygen concentration with a training machine capable of applying a ramped load, which means that these systems do not need to use any specialized measuring device under an expert's guidance and thus can be introduced to gyms, etc., for example.

[0083] Under the first estimation method and estimation system, the method for determining a starting point of decline from the measured value of SpO.sub.2 is not specifically limited; however, methods 1-1 and 1-2 below can be mentioned, for example.

Method for Determining Starting Point of Decline 1-1 (Also Referred to as Method 1-1)

[0084] A method that measures the pulse rate simultaneously with the SpO.sub.2 and determines a starting point of decline based on change in SpO.sub.2 over time, wherein the method is such that, once the pulse rate first exceeds the target pulse rate, the value of SpO.sub.2 at the time the pulse rate first exceeded the target pulse rate is used as a reference value, and the measurement point of SpO.sub.2 immediately before a range where the measured value of SpO.sub.2 indicated a value lower than the reference value consecutively for 5 seconds or longer is determined as a starting point of decline.

Method for Determining Starting Point of Decline 1-2 (Also Referred to as Method 1-2)

[0085] A method that measures the pulse rate simultaneously with the SpO.sub.2 and determines a starting point of decline based on change in SpO.sub.2 over time, wherein the method is such that, once the pulse rate first exceeds the target pulse rate, the value of SpO.sub.2 at the time the pulse rate first exceeded the target pulse rate is used as a reference value, and the point of intersection between a straight line connecting the measurement point of the highest value and the measurement point of the lowest value, of SpO.sub.2, within a range where the measured value of SpO.sub.2 is lower than the reference value consecutively for 5 seconds or longer, and an approximate straight line determined before the aforesaid range, is set as a starting point of decline. If there are two or more measurement points giving the highest value or lowest value, one of such values obtained first chronologically is used as the measurement point of the highest value or lowest value.

[0086] Under the second estimation method and estimation system, the method for determining an inflection point of the calculated SpO.sub.2/pulse rate is not specifically limited; however, method 2 below can be mentioned, for example.

Method for Determining Inflection Point 2 (Also Referred to as Method 2)

[0087] A method that measures the pulse rate simultaneously with the SpO.sub.2 and, by using the pulse rate as an independent variable and the value obtained by dividing the SpO.sub.2 by the pulse rate (SpO.sub.2/pulse rate) as a dependent variable, and also based on a combination of regression line 1 covering the first measurement point to the nth (n?2) measurement point and regression line 2 covering the (n+1)th measurement point to the Nth measurement point (N?n+2), determines the point of intersection between regression lines 1 and 2 when the sum of the residual sums of squares of regression lines 1 and 2 becomes the smallest, as an inflection point.

[0088] It should be noted that residual mean squares may be used in place of residual sums of squares.

[0089] Under methods 1-1 and 1-2, the target pulse rate may be any value such as that used as a reference for aerobic exercise; for example, a value of target heart rate derived by the Karvonen formula {(220?age?stationary heart rate)?(0.4 to 0.7)+stationary heart rate}, or a simplified version of it (220?age)?0.5 to 0.7, may be used, for example, or simply a value of around 120 to 130 beats per minute may be used.

[0090] Under methods 1-1 and 1-2, the number of seconds over which the measured value of SpO.sub.2 indicates a value lower than the reference value (value of SpO.sub.2 at the time the pulse rate first exceeded the target pulse rate) only needs to be 5 seconds or more. The longer the time in seconds, the lower the possibility becomes of determining a wrong starting point of decline based on measured values deviating from the trend; however, a longer measurement time increases physical burden on the subject. Accordingly, the lower limit of the time in seconds is preferably 8 seconds or more, or more preferably 10 seconds or more, while the upper limit of these seconds is preferably 60 seconds or less, or more preferably 50 seconds or less, or yet more preferably 40 seconds or less.

[0091] Also, preferably determination is made based on measured values from two or more consecutive multiple measurements to prevent misdetermination caused by a single measuring error. Specifically, when the measured values of SpO.sub.2 are obtained as average values over 1 to 30 seconds or so, preferably the value obtained by multiplying the number of seconds over which to calculate a measured value (average value) of SpO.sub.2 by (number of measurements?1) is 5 seconds or longer, and, at the same time, two or more consecutive multiple measurement points deliver values lower than the reference value.

[0092] Under the first estimation method, no more exercise under ramped load is needed once this starting point of decline has been determined and the measurement can be terminated there, which means that there is no need to continue exercising until one cannot exercise any further, and consequently physical burden on the subject can be minimized.

[0093] Under method 2, where continuous exercising is required until an inflection point occurs, the measurement is continued preferably until 140 beats per minute is reached, or more preferably until 150 beats per minute is reached, or yet more preferably until 155 beats per minute is reached, or most preferably until 160 beats per minute is reached. However, this upper limit is preferably no more than 85%, or more preferably no more than 83%, or yet more preferably no more than 80%, of the expected maximum heart rate (220?age) of the subject.

[0094] Under method 2, when regression line 1 derived from the measurement points from the first measurement point up to the mth, and regression line 2 derived from the measurement points from the (m+1)th measurement point up to the Mth measurement point, are used in combination to obtain the sum of the residual sums of squares of regression lines 1 and 2, if the sum becomes the smallest, the exercise is continued up to the (M+p)th measurement point; and when regression line 1, and regression line 2 derived from the measurement points from the (m+1)th measurement point up to the (M+p)th measurement point, are used in combination to obtain the sum of the residual sums of squares of them, and the sum becomes again the smallest, an inflection point may be determined there, and further exercise can be stopped. If the exercise is stopped prematurely as described above, M is preferably 5 or greater, while p is preferably 2 or greater. Additionally, the measurement time from the first to mth measurements, and that from the (m+1)th to Mth measurements, are each preferably 20 seconds or longer, or more preferably 30 seconds or longer, or yet more preferably 40 seconds or longer. Also, the measurement time from the Mth to (M+p)th measurements is preferably 10 seconds or longer, or more preferably 15 seconds or longer, or yet more preferably 20 seconds longer.

[0095] Under the second estimation method, exercise needs to be performed only within a prescribed range of pulse rates, and since there is no need to continue exercising until one cannot exercise any further, physical burden on the subject can be minimized.

Training Method

[0096] The training method proposed by the present invention is characterized in that exercise is performed at the optimal exercise intensity estimated by the aforementioned estimation method.

[0097] Using the estimation method proposed by the present invention, the workload at the starting point of decline or inflection point can be estimated as an optimal exercise intensity for the subject. Then, because this estimated optimal exercise intensity approximates the workload intensity at the AT, a training method that involves exercising at this optimal exercise intensity can efficiently improve one's body strength. On the other hand, one can expect hardly any improvement in his/her body strength by exercising continuously at exercise intensities lower than his/her optimal exercise intensity estimated by this estimation method, while exercising at exercise intensities higher than the optimal exercise intensity estimated by this estimation method may lead to injury or accumulation of fatigue.

Exercise Instruction Device

[0098] The exercise instruction device proposed by the present invention is characterized in that it comprises: a storage means for storing biological information values at the optimal exercise intensity estimated by the estimation method proposed by the present invention; a measurement means capable of measuring the biological information values; and an instruction means for indicating a workload by comparing the biological information values measured by the measurement means against the biological information values at the optimal exercise intensity.

[0099] The exercise instruction device proposed by the present invention may also have, besides the above, a storage means such as a memory, a communication means, a display means, a CPU or other computation means, a battery, and so on. Also, the storage means and computation means may be such that its processing takes place at least partially on an external server with which the exercise instruction device communicates through the communication parts.

[0100] The mode of the exercise instruction device proposed by the present invention is not specifically limited; for example, it may be built into a training machine or constitute an external terminal connected to a training machine, or it may be, for example, a smartphone, smart watch, smart glasses, earpiece, etc., that is made capable of implementing the aforementioned means by installing an application therein. Of these, preferably the exercise instruction device proposed by the present invention is a smart watch, smart glasses, or other wearable terminal.

[0101] The biological information values measured/stored by the exercise instruction device proposed by the present invention include the SpO.sub.2, pulse rate, blood pressure, sweat lactate concentration, etc., of which one type or two or more types may be measured/stored. Of these, preferably the SpO.sub.2 and pulse rate are measured and stored because of their ease of measurement.

[0102] The exercise instruction device proposed by the present invention can, by having the computation means compare biological information values at the estimated optimal exercise intensity stored by the storage means against biological information values measured by the measurement means, calculate the difference between current exercise intensity and optimal exercise intensity to calculate an optimal workload. Here, preferably the user is able to set a workload lower then, equal to, higher than, or the like, the optimal exercise intensity according to how he/she feels or his/her physical condition, etc., that day. Then, by exercising at the exercise intensity instructed by the exercise instruction device proposed by the present invention, the user can efficiently improve his/her body strength.

[0103] Furthermore, preferably the exercise instruction device proposed by the present invention is such that the measurement means can measure the SpO.sub.2, the instruction means can indicate a workload that will be used as a ramped load, and the computation means can calculate a starting point of decline at which the measured value of blood oxygen concentration starts to show a declining trend as the workload increases.

[0104] Or, preferably the measurement means can measure the SpO.sub.2 and pulse rate, the instruction means can indicate, based on information, a workload that will be used as a ramped load, and the computation means can calculate an inflection point at which the behavior of SpO.sub.2/pulse rate changes as the workload increases.

[0105] Such exercise instruction device can estimate the user's optimal exercise intensity by virtue of its ability to indicate a workload that will be used as a ramped load and to calculate a starting point of decline at which the measured value of SpO.sub.2 starts to show a declining trend or an inflection point at which the behavior of SpO.sub.2/pulse rate changes. Therefore, assume that the body strength has been improved by exercising continuously for a while at the estimated optimal exercise intensity instructed by the exercise instruction device proposed by the present invention and thus the body strength can no longer be improved at this exercise intensity; even in this situation, by obtaining the latest optimal exercise intensity, exercise can be conducted at this exercise intensity representing a higher load.

EXAMPLES

Examples

Workload Application Method 1

[0106] Equipment used: Ergometer [0107] Load application method: Ramped load method [0108] Ergometer settingCrank speed 120 bpm [0109] The saddle is adjusted so that the subject's knee bends slightly when the pedal is at the lowest point. [0110] Resting conditionRest for 2 periods in a seated position (seated on the ergometer). [0111] Warm-up condition5 minutes at 50 watts [0112] Workload application conditionRamped load increment 10 watts/min [0113] Stopping conditionLoad is lifted when one of the following conditions is satisfied: [0114] 1) The subject can no longer continue exercising at 120 rpm due to fatigue in the lower limbs. [0115] 2) The person in charge of testing determines that the test should be aborted. [0116] Unit of load: watt

[0117] Workload application method 2 [0118] Equipment used: Treadmill [0119] Load application method: Ramped load method [0120] Resting conditionRest for 2 periods in a seated position. [0121] Warm-up condition5 minutes at 5 km/h [0122] Workload application conditionRamped load increment 1 km/h/min [0123] Stopping conditionLoad is lifted when one of the following conditions is satisfied: [0124] 1) The subject can no longer continue exercising due to fatigue in the lower limbs. [0125] 2) The person in charge of testing determines that the test should be aborted. Unit of load: km/h

(Measurement of SpO.SUB.2 .and Pulse Rate)

[0126] The oxygen saturation and pulse rate were measured using a pulse oximeter (NELLCOR? N-BSJ (Covidien Japan Inc.)).

[0127] The SpO.sub.2 and pulse rate were measured at 4-second intervals and averaged every 20 seconds.

[0128] It was performed in a SpO.sub.2 range of 96 to 100% and with the upper limit of pulse rate and target pulse rate set to 160 beats per minute and 120 beats per minute, respectively.

(Breath Gas Parameters and Measurement of Heart Rate)

[0129] Measuring equipment: Breath gas analyzer AEROMONITOR AE-310SRC (Minato Medical Science Co., Ltd.), heart rate meter POLAR, heart rate sensor H10 N

[0130] Measuring method: Mixing chamber method

[0131] Measured items: Carbon dioxide production (VCO.sub.2: ml/min), oxygen consumption (VO.sub.2: ml/min), minute ventilation (VE), end-tidal partial pressure of oxygen tension (PETO.sub.2), end-tidal partial pressure of carbon dioxide (PETCO.sub.2), end-tidal oxygen concentration (ETO.sub.2), end-tidal carbon dioxide concentration (ETCO.sub.2), gas exchange rate (R=VCO.sub.2/VO.sub.2)*, ventilatory equivalent for oxygen (VE/VO.sub.2)*, ventilatory equivalent for carbon dioxide (VE/VCO.sub.2)*, heart rate (HR: bpm)*Calculated value

[0132] Data acquisition frequency: Once every 20 seconds

[0133] The VE/VO.sub.2, and simultaneously SpO.sub.2 and pulse rate, were measured on subjects A to C while a workload was given by workload application method 1 (ergometer), and on subjects D to F while a workload was given by workload application method 2 (treadmill). With every subject, measurement was performed until the person could no longer continue exercising, i.e., until the subject's maximum intensity was reached.

[0134] Table 1 shows, in the order of measurement, the results of SpO.sub.2 and pulse rate taken at 15 measurement points that were arranged so that the target heart rates would appear at point no. 4. It should be noted that the measured values of subject B at point no. 10 were excluded because the pulse rate decreased from the value immediately before.

TABLE-US-00001 TABLE 1 A B C D E F Pulse Pulse Pulse Pulse Pulse Pulse No. SpO.sub.2 rate SpO.sub.2 rate SpO.sub.2 rate SpO.sub.2 rate SpO.sub.2 rate SpO.sub.2 rate 1 99.0 118 100.0 119 97.0 117 100.0 111 100.0 114 98.4 110 2 98.2 117 100.0 118 97.0 117 100.0 113 100.0 114 98.4 112 3 98.8 120 100.0 118 97.0 119 100.0 114 100.0 116 98.8 118 4 99.0 121 99.6 124 97.4 121 100.0 121 100.0 121 98.8 122 5 99.0 122 100.0 124 97.0 124 100.0 129 100.0 125 99.0 126 6 99.0 126 99.8 127 97.0 127 100.0 146 100.0 127 99.0 133 7 99.0 127 99.6 129 97.4 128 99.8 150 99.6 133 99.2 138 8 99.0 127 99.6 132 97.2 131 99.6 152 100.0 141 99.0 139 9 98.6 130 99.6 132 96.6 131 97.8 149 100.0 140 99.0 143 10 98.0 133 99.6 129 96.8 133 98.0 153 99.4 147 98.6 145 11 98.4 135 99.4 135 96.0 135 98.4 154 99.6 150 97.8 146 12 98.4 136 99.0 138 97.0 139 99.0 158 99.2 148 98.0 151 13 98.0 139 99.0 139 96.6 141 99.0 152 99.6 157 99.0 159 14 98.0 142 99.2 141 96.2 140 98.0 159 100.0 160 99.0 159 15 98.0 145 98.4 149 96.6 145 97.4 155 100.0 162 99.0 164

Determination of AT by GS Method

[0135] By plotting the data taken every 20 seconds from the start of ramped load application until it was stopped, the point at which the VE/VCO.sub.2 did not increase but the VE/VO.sub.2 did, with respect to the exercise intensity, was determined as the AT.

Determination of Starting Point of Decline by Method 1-1

[0136] Under method 1-1, the value of SpO.sub.2 when the pulse rate first exceeded the target pulse rate (120 beats per minute) was used as a reference value, and the measurement point of SpO.sub.2 immediately before a range where the measured value of SpO.sub.2 indicated a value lower than this reference value for 40 seconds (20 seconds?(3-1)) was determined as starting point of decline 1.

[0137] FIG. 1 shows how the SpO.sub.2 and pulse rate of subject A changed over time. In the case of subject A, for example, whose reference value is 99 corresponding to the SpO.sub.2 at point no. 5, the SpO.sub.2 indicated a value lower than this reference value for 40 seconds from point nos. 9 to 11, and therefore the measurement point immediately before this, or point no. 8, was determined as a starting point of decline. Then, the workload at this starting point of decline (workload giving a heart rate of 127) was estimated as an optimal exercise intensity for subject A.

[0138] According to method 1-1, subject A needs to exercise only until point no. 11 to allow for estimation of optimal exercise intensity, upon which the measurement (exercise) can be terminated.

Determination of Starting Point of Decline by Method 1-2

[0139] Under method 1-2, the value of SpO.sub.2 at the time the pulse rate first exceeded the target pulse rate (120 beats per minute) was used as a reference value, and the point of intersection between a straight line connecting the measurement point of the highest value and the measurement point of the lowest value, of SpO.sub.2, within a range where the measured value of SpO.sub.2 was lower than the above reference value for 40 seconds (20 seconds?(3-1)), and an approximate straight line determined before the aforesaid range (from 120 beats up to immediately before the range), was set as starting point of decline 2.

[0140] FIG. 2 shows a scatter plot of the SpO.sub.2 and pulse rate of subject A. With subject A, after the pulse rate had first exceeded the target heart rate, the pulse rate increased as the workload increased. In the case of subject A, for example, whose reference value is 99 corresponding to the SpO.sub.2 at point No. 5, the values of the SpO.sub.2 from point Nos. 9 to 11 for 40 seconds were lower than this reference value, wherein the highest point was No. 9 and the lowest point was No. 10. The point of intersection (SpO.sub.2, pulse rate=99, 128) between a straight line connecting these two points, and an approximate straight line derived from point Nos. 4 to 8 (all of their SpO.sub.2 being 99), i.e., after exceeding 120 beats immediately before this range, was set as a starting point of decline. Then, the workload at this starting point of decline (workload giving a heart rate of 128) was estimated as an optimal exercise intensity for subject A.

[0141] According to method 1-2, subject A needs to exercise only until point No. 11 to allow for estimation of optimal exercise intensity, upon which the measurement (exercise) can be stopped.

Determination of Inflection Point by Method 2

[0142] Under method 2, the pulse rate was measured simultaneously with the SpO.sub.2, and by using the pulse rate as an independent variable and the value obtained by dividing the SpO.sub.2 by the pulse rate as a dependent variable, regression line 1 derived from the first measurement point up to the Nth (N?2) measurement point and regression line 2 derived from the N+1th measurement point up to the last measurement point are used in combination to determine the sum of the residual sums of squares of two regression lines 1 and 2, and if the sum became the smallest, the point of intersection between regression lines 1 and 2 was set as an inflection point.

[0143] FIG. 3 shows a scatter plot of the pulse rate at and after 110 (including point Nos. 1 to 15), and SpO.sub.2/pulse rate, of subject A. It should be noted that subject A could no longer continue exercising after 2 minutes of exercise upon point No. 15, at which time the subject's SpO.sub.2 was 98.0 and pulse rate was 148. When these plotted points were divided into two and the sum of the residual sums of squares of the two respective regression lines was obtained, the sum of the residual sums of squares became the smallest when the points were divided into the measurement points up to No. 9 and the measurement points from No. 10 and thereafter, and therefore the point of intersection between these two regression lines (pulse rate, SpO.sub.2/pulse rate=127, 0.78) was set as an inflection point. Then, the workload at this inflection point (workload giving a heart rate of 127) was estimated as an optimal exercise intensity for subject A.

[0144] According to method 2, as it is applied to subject A, the sum of the residual sums of squares becomes the smallest even when the measurement points extended until 140 beats per minute was reached (point No. 13) wherein the measurement points were divided into the point up to No. 9 and point Nos. 10 to 13, and since this allows for estimation of an optimal exercise intensity equivalent to when exercise was continued until the subject could not exercise any further (2 more minutes past point No. 15), the measurement (exercise) can be stopped at point No. 13.

[0145] Table 2 shows the optimal exercise intensities estimated by the respective methods mentioned above, together with the optimal exercise intensities measured by the golden standard method (GS method) based on breath gas analysis.

TABLE-US-00002 TABLE 2 Pulse Rates at Optimal Exercise Intensities A B C D E F GS method 115 139 134 145 139 146 Method 1-1 127 132 128 146 140 143 Method 1-2 128 134 131 150 144 144 Method 2 127 132 137 134 138 147

[0146] It was confirmed that optimal exercise intensities approximating the optimal exercise intensities measured by the conventional gold standard method (GS method) based on breath gas analysis can be estimated according to the estimation methods conforming to the present invention.

[0147] In the case of subject A, for example, an optimal exercise intensity can be estimated by exercising until measurement point no. 11 according to methods 1-1 and 1-2, upon which the measurement (exercise) can be terminated; according to method 2, on the other hand, an optimal exercise intensity can be estimated by exercising until measurement point no. 13. The estimation methods conforming to the present invention eliminate the need to exercise to the limit (until the subject cannot exercise any further), and since they do not require a blood draw, either, physical and mental burdens are minimized.