Lactate threshold derivation device, method, program, and recording medium

Abstract

To accurately derive a lactate threshold on the basis of a measurement result of a lactic acid value in sweat.SOLUTION: A lactate threshold derivation device 20 comprises: a measurement result recording unit 22 that records measurement results of an amount of lactate in a subject's sweat in association with time; a load recording unit 24 that records a load applied to the subject in association with time; a maximum value derivation unit 26 that derives maximum values of the measurement results in association with the load; and a lactate threshold derivation unit 28 that derives a lactate threshold of the subject on the basis of a load at a change point where a rate of increase in the maximum values with respect to the load changes to a decrease. The load is the load during exercise when cycles in which rests are taken after exercise are repeated multiple times after warm-up of the subject, and the load increases with each cycle.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to the measurement of lactate threshold. [Background technology]

[0002] It has been known that physical fitness can be assessed by measuring the exercise intensity at which lactic acid begins to accumulate in the blood (i.e., the lactate threshold).

[0003] The lactate threshold can be measured by drawing blood, but because drawing blood is invasive, it is preferable to measure the lactate threshold non-invasively.

[0004] Therefore, attempts have been made to derive the lactate threshold based on the results of measuring the lactate level in sweat (see Patent Document 1 and Non-Patent Documents 1 to 8). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2023 / 126525 [Non-patent literature]

[0006] [Non-Patent Document 1] Xing Xuan et.al., “Fully Integrated Wearable Device for ContinuousSweat Lactate Monitoring in Sports”, American Chemical Society Sensors June 8, 2023, 8, p. 2401-2409 [Non-patent document 2] H.Okawara et.al., "Anaerobic threshold using sweat lactate sensorunder hypoxia", Nature Portfolio Scientific Reports, December 21, 2023, 13(1), 22865 [Non-licensed document 3] Y.Muramoto et.al., "Estimation of maximal lactate steady state using the sweat lactate sensor" Nature Portfolio Scientific Reports, June 26, 2023, 13(1), 10366

Non-licensed Document 4

Non-licensed Document 5

Non-licensed Document 6

Non-licensed Document 7

[0007] If most of the lactic acid in sweat is lactic acid that has seeped out of the blood and dissolved into the sweat, then at the lactate threshold, not only the lactic acid level in the blood but also the lactic acid level in the sweat will begin to rise.

[0008] However, the lactic acid in sweat is mostly lactic acid that has seeped out of the blood and dissolved into the sweat. Rather, it is thought that the majority of the lactic acid in sweat is lactic acid produced by the muscle exercise that controls sweating.

[0009] Therefore, it is not the case that lactate levels in sweat begin to rise at the lactate threshold, making it difficult to accurately derive the lactate threshold based on the results of measuring lactate levels in sweat.

[0010] Therefore, an object of the present invention is to accurately derive the lactate threshold based on the measurement results of the lactate level in sweat. [Means for solving the problem]

[0011] The first lactate threshold derivation device of the present invention comprises a measurement result recording unit that records measurement results of the amount of lactate in the sweat of a subject in correspondence with time; a load recording unit that records the load applied to the subject in correspondence with time; a maximum value derivation unit that derives the maximum value of the measurement result in correspondence with the load; and a lactate threshold derivation unit that derives the lactate threshold of the subject based on the load at the change point where the rate of increase of the maximum value relative to the load changes to a decrease, wherein the load is the load during exercise when a cycle of the subject's warm-up exercise followed by rest is repeated multiple times, and the load is configured to increase with each cycle.

[0012] In the first lactate threshold deriving device configured as described above, the measurement result recording unit records the measurement results of the amount of lactate in the subject's sweat in correspondence with time. The load recording unit records the load applied to the subject in correspondence with time. The maximum value deriving unit derives the maximum value of the measurement results in correspondence with the load. The lactate threshold deriving unit derives the lactate threshold of the subject based on the load at the change point where the rate of increase of the maximum value relative to the load changes to a decrease. The load is the load during the subject's exercise when a cycle of warm-up exercise followed by rest after exercise is repeated multiple times. The load increases with each cycle.

[0013] The second lactate threshold derivation device of the present invention comprises a measurement result recording unit that records measurement results of the amount of lactate in the subject's sweat in correspondence with time; a load recording unit that records the load applied to the subject in correspondence with time; a total derivation unit that derives the sum of measurement results around the time when the measurement result takes a maximum value in correspondence with the load; and a lactate threshold derivation unit that derives the subject's lactate threshold based on the load at the change point where the rate of increase of the sum relative to the load changes to a decrease, wherein the load is the load during exercise when a cycle of the subject's warm-up exercise followed by rest is repeated multiple times, and the load is configured to increase with each cycle.

[0014] In the second lactate threshold deriving device configured as described above, the measurement result recording unit records the measurement results of the amount of lactate in the subject's sweat in correspondence with time. The load recording unit records the load applied to the subject in correspondence with time. The sum deriving unit derives the sum of the measurement results around the time when the measurement result reaches its maximum value in correspondence with the load. The lactate threshold deriving unit derives the subject's lactate threshold based on the load at the change point where the rate of increase of the sum relative to the load changes to a decrease. The load is the load during the subject's exercise when a cycle of warm-up exercise followed by rest after exercise is repeated multiple times. The load increases with each cycle.

[0015] In the first and second lactate threshold deriving devices according to the present invention, the lactate threshold deriving section may set the load at the change point as the lactate threshold.

[0016] In addition, the first and second lactate threshold derivation devices of the present invention may be configured so that the lactate threshold derivation unit determines the lactate threshold as the load between the load at the change point and the load one cycle after the load at the change point.

[0017] In the first and second lactate threshold deriving devices according to the present invention, the warm-up exercise may be performed for a predetermined time period at a predetermined heart rate of the subject.

[0018] In the first and second lactate threshold deriving devices according to the present invention, the rest period may be longer than the exercise period.

[0019] The present invention is a lactate threshold derivation method comprising a measurement result recording step of recording measurement results of the amount of lactate in the sweat of a subject in correspondence with time; a load recording step of recording the load applied to the subject in correspondence with time; a maximum value derivation step of deriving a maximum value of the measurement results in correspondence with the load; and a lactate threshold derivation step of deriving the lactate threshold of the subject based on the load at a change point where the rate of increase of the maximum value with respect to the load changes to a decrease, wherein the load is the load applied during exercise when a cycle of the subject's warm-up exercise followed by rest is repeated multiple times, and the load increases with each cycle.

[0020] The present invention is a lactate threshold derivation method comprising a measurement result recording step of recording measurement results of the amount of lactate in the sweat of a subject in correspondence with time; a load recording step of recording the load applied to the subject in correspondence with time; a sum derivation step of deriving the sum of measurement results around the time when the measurement result takes a maximum value in correspondence with the load; and a lactate threshold derivation step of deriving the lactate threshold of the subject based on the load at a change point where the rate of increase of the sum relative to the load changes to a decrease, wherein the load is the load applied during exercise when a cycle of warm-up exercise followed by rest after the exercise is repeated multiple times by the subject, and the load increases with each cycle.

[0021] The present invention is a program for causing a computer to execute a lactate threshold derivation process, the lactate threshold derivation process comprising a measurement result recording step of recording the measurement results of the amount of lactate in the sweat of a subject in correspondence with time, a load recording step of recording the load applied to the subject in correspondence with time, a maximum value derivation step of deriving the maximum value of the measurement results in correspondence with the load, and a lactate threshold derivation step of deriving the lactate threshold of the subject based on the load at the change point where the rate of increase of the maximum value with respect to the load changes to a decrease, the load being the load during exercise when a cycle of the subject's warm-up exercise followed by rest is repeated multiple times, and the load increases with each cycle.

[0022] The present invention is a program for causing a computer to execute a lactate threshold derivation process, the lactate threshold derivation process comprising a measurement result recording step of recording measurement results of the amount of lactate in the sweat of a subject in correspondence with time; a load recording step of recording the load applied to the subject in correspondence with time; a sum derivation step of deriving the sum of measurement results around the time when the measurement result takes a maximum value in correspondence with the load; and a lactate threshold derivation step of deriving the lactate threshold of the subject based on the load at the change point where the rate of increase of the sum relative to the load changes to a decrease, the load being the load during exercise when a cycle of warm-up exercise followed by rest after the exercise is repeated multiple times by the subject, and the load increases with each cycle.

[0023] The present invention is a computer-readable recording medium having recorded thereon a program for causing a computer to execute a lactate threshold derivation process, the lactate threshold derivation process comprising a measurement result recording step of recording measurement results of the amount of lactate in a subject's sweat in correspondence with time, a load recording step of recording the load applied to the subject in correspondence with time, a maximum value derivation step of deriving a maximum value of the measurement results in correspondence with the load, and a lactate threshold derivation step of deriving the subject's lactate threshold based on the load at a change point where the rate of increase of the maximum value relative to the load changes to a decrease, the load being the load during exercise when a cycle of the subject's warm-up exercise followed by rest is repeated multiple times, and the load increases with each cycle.

[0024] The present invention is a computer-readable recording medium having recorded thereon a program for causing a computer to execute a lactate threshold derivation process, the lactate threshold derivation process comprising a measurement result recording step for recording measurement results of the amount of lactate in the sweat of a subject in correspondence with time, a load recording step for recording the load applied to the subject in correspondence with time, a total derivation step for deriving the sum of measurement results around the time when the measurement result takes a maximum value in correspondence with the load, and a lactate threshold derivation step for deriving the lactate threshold of the subject based on the load at the change point where the rate of increase of the sum relative to the load changes to a decrease, the load being the load during exercise when a cycle of warm-up exercise followed by rest after the exercise is repeated multiple times by the subject, and the load increases with each cycle. [Brief explanation of the drawings]

[0025] [Figure 1] 1A and 1B are a plan view and a front view, respectively, of a lactate measuring device according to an embodiment of the present invention. [Figure 2] 2 is a cross-sectional view of the substrate 140 taken along the line II-II. [Figure 3] 1 is a functional block diagram showing the configuration of a lactate threshold derivation device 20 according to an embodiment of the present invention. [Figure 4] 3 is a diagram showing an example of the recorded contents of the measurement result recording unit 22 and the load recording unit 24. FIG. [Figure 5] 10 is a diagram showing an example of a result derived by a local maximum value deriving unit 26. FIG. [Figure 6] 10 is a diagram showing another example of the result derived by the maximum value deriving unit 26. FIG. [Figure 7] FIG. 2 is a functional block diagram showing the configuration of a lactate threshold derivation device 20 according to a modified embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0027] FIG. 1 is a plan view (FIG. 1(a)) and a front view (FIG. 1(b)) of a lactate measuring device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the substrate 140 taken along line II-II. However, for convenience of illustration, the measuring device 16 (see FIG. 2) is omitted from FIG. 1.

[0028] The lactate measuring device according to the embodiment of the present invention comprises substrates 130 and 140, a PBS supply unit 10, a pump 17, a waste liquid storage unit 18, and tubes T0, T1, T2, and T3. Although the tubes T0, T1, T2, and T3 are shown as straight lines for the sake of convenience, they are actually curved and have slack.

[0029] The PBS supply unit 10 stores PBS (phosphate-buffered saline) and supplies PBS to the flow channel 13 and the flow channel 14. The PBS supply unit 10 is attached to the inlet 13a of the flow channel 13 via a tube T0.

[0030] The substrate 130 has a flow channel 13. The flow channel 13 has an inlet 13a and an outlet 13b. The substrate 130 is placed on the skin 2 of the subject.

[0031] Flow path 13 is a linear flow path connected to inlet 13a and outlet 13b. Flow path 13 is placed on the skin 2 of the subject. Flow path 13 is open to the bottom surface of substrate 130. Liquid (PBS) flows in from inlet 13a. The liquid (PBS) flows toward outlet 13b together with sweat on the skin 2. Inlet 13a is a circular hole that penetrates substrate 130. Outlet 13b is another circular hole that penetrates substrate 130.

[0032] Substrate 140 has a flow path 14. Flow path 14 has an inlet 14a and an outlet 14b. Flow path 14 is a linear flow path connected to inlet 14a and outlet 14b. Liquid (PBS containing sweat) flows in from inlet 14a. The liquid (PBS containing sweat) flows toward outlet 14b together with sweat. Inlet 14a is a circular hole opened in substrate 140. Outlet 14b is a circular hole opened in substrate 140. In addition, inlet 14a is attached to outlet 13b.

[0033] The pump 17 sucks the liquid (PBS containing sweat) from the outlet 14b and supplies it to the waste liquid storage portion 18. The pump 17 is attached to the outlet 14b via a tube T2. The pump 17 is also attached to the waste liquid storage portion 18 via a tube T3.

[0034] The waste liquid reservoir 18 is attached to the pump 17 via a tube T3. The liquid (including sweat) sucked out by the pump 17 is stored as waste liquid in the waste liquid reservoir 18 via the tube T3.

[0035] The measuring device 16 measures the amount of lactic acid in the subject's sweat. The measuring device 16 may be, for example, an electrochemical sensor, a calorimetric sensor, or a quartz crystal microbalance sensor. In this embodiment, the measuring device 16 is a well-known electrochemical sensor.

[0036] The measuring device 16 has electrodes CE, WE, and RE, wires 162C, 164C, 162W, 164W, 162R, and 164R, and a substrate 166.

[0037] Electrode CE is the counter electrode, electrode WE is the working electrode, and electrode RE is the reference electrode (e.g., silver The electrode CE is connected to a thin wire 162C, which is connected to a thick wire 164C. The electrode RE is connected to a thin wire 162R, which is connected to a thick wire 164R. The electrode WE is connected to a thin wire 162W, which is connected to a thick wire 164W. The wires 164C, 164R, and 164W are arranged on a substrate 166. The wires 164C, 164R, and 164W are connected to a potentiostat (not shown), which provides an output corresponding to the concentration of lactic acid in the sweat.

[0038] The electrode WE has a layer of carbon graphite mixed with Prussian blue (hereinafter referred to as "carbon graphite layer (with Prussian blue)"), and a layer of lactate oxidase is formed on the carbon graphite layer (with Prussian blue). The electrode CE is a layer of carbon graphite. The electrode RE has a layer of silver-silver chloride formed on the carbon graphite layer.

[0039] Although the measuring device 16 is not shown in Fig. 1, it is actually attached to a substrate 140 of the lactate measuring device as shown in Fig. 2. Electrodes CE, WE, and RE, which are part of the measuring device 16, are partially disposed inside the flow path 14.

[0040] Although the measuring device 16 has been described as having one working electrode (electrode WE), it is also possible to provide multiple working electrodes (electrodes WE), each with a different enzyme layer disposed thereon, and measure different components.

[0041] 3 is a functional block diagram showing the configuration of a lactate threshold derivation device 20 according to an embodiment of the present invention. The lactate threshold derivation device 20 according to an embodiment of the present invention includes a measurement result recording unit 22, a load recording unit 24, a maximum value derivation unit 26, and a lactate threshold derivation unit 28.

[0042] The measurement result recording unit 22 receives the measurement result of the amount of lactic acid in the subject's sweat from the measuring device 16 and records the measurement result in association with time. The load recording unit 24 records the load applied to the subject in association with time.

[0043] FIG. 4 shows an example of the recorded contents of the measurement result recording unit 22 and the load recording unit 24. However, the example shown in FIG. 4 is an example in which the load applied to the subject is a load during exercise in which the subject performs a warm-up exercise, followed by a rest period, and the cycle is repeated multiple times. However, it is assumed that the load increases with each cycle. This warm-up exercise is performed for a predetermined period of time at a predetermined heart rate. Furthermore, it is assumed that the rest period is longer than the exercise period.

[0044] The example shown in Figure 4 was obtained by applying a load to a subject using the following procedure.

[0045] (Step 1) The subject performs warm-up exercises for about 10 minutes (predetermined time) so that their heart rate reaches about 110 beats per minute (predetermined number of beats per minute).

[0046] Step 1 causes the subject to sweat slightly, which expels waste products from the sweat glands, enabling the lactate threshold to be accurately calculated.

[0047] (Step 2) Exercise followed by rest constitutes one cycle, and the load is increased with each cycle.

[0048] However, exercise is performed using an exercise bike (registered trademark), and the exercise is performed for 3 minutes, followed by a 4-minute rest period (longer than the exercise time).

[0049] After three minutes of exercise, the amount of lactate in the blood rises sufficiently. After four minutes of rest, the change points described below (see Figures 5 and 6) occur. However, the load increases from 70W to 85W, 100W, 115W, 130W, 145W, and 160W for each cycle.

[0050] 4, the horizontal axis represents the time [minutes] from the start of Procedure 2, and the vertical axis represents the amount of lactate in sweat SL [nA]. However, since the current [nA] output by measuring device 16 corresponds to the concentration of lactate in sweat, the current [nA] output by measuring device 16 is shown as the amount of lactate in sweat SL [nA].

[0051] As an example, the measurement result recording unit 22 records the correspondence shown by graph SL in Fig. 4. Graph SL shows that the amount of lactic acid in sweat SL rises, reaches a maximum value, and then falls at approximately times 0 to 10 minutes, 10 to 15 minutes, 15 to 20 minutes, and so on.

[0052] Furthermore, in step 2, the exercise and rest times in one cycle (3 minutes and 4 minutes, respectively) are known, and the load increases for each cycle from 70W, 85W, 100W, 115W, 130W, 145W, to 160W, so the load for each time can be determined.

[0053] In Figure 4, 70W, 85W, 100W, etc. are shown near the maximum values ​​of graph SL, and the load recording unit 24 records the load during exercise from 0 to 10 minutes, 10 to 15 minutes, 15 to 20 minutes, etc. as 70W, 85W, 100W, etc.

[0054] The amount of sweat SR in FIG. 4 is shown for reference, but is not measured by the lactate measuring device and lactate threshold derivation device 20 according to the embodiment of the present invention.

[0055] The local maximum value deriving section 26 derives the local maximum value of the measurement result (for example, graph SL in FIG. 4) in association with the load based on the contents recorded in the measurement result recording section 22 and the load recording section 24.

[0056] Fig. 5 is a diagram showing an example of the results derived by the maximum value derivation unit 26. Fig. 5 illustrates the amount of lactic acid in sweat (maximum value) SL [nA], assuming that the measurement results are as shown in graph SL in Fig. 4.

[0057] The maximum value deriving unit 26 performs a peak search on the recorded contents (graph SL in FIG. 4 ) of the measurement result recording unit 22 to determine the maximum value of the measurement result. Next, the maximum value deriving unit 26 refers to the measurement result and determines the time associated with the maximum value of the measurement result. Finally, the maximum value deriving unit 26 reads out the load associated with the determined time from the load recording unit 24.

[0058] For example, the local maximum value derivation unit 26 determines the local maximum value (approximately 92 [nA]) (however, the earliest one) of the graph SL in FIG. 4. Next, the local maximum value derivation unit 26 determines the time (approximately 4 to 6 [minutes]) associated with the local maximum value (approximately 92 [nA]) of the graph SL in FIG. 4. Finally, the local maximum value derivation unit 26 reads out the load (70 [W]) associated with the determined time from the load recording unit 24. This makes it possible to determine the coordinates (70 [W], 92 [nA]) of the leftmost point of the sweat lactate amount (local maximum value) SL [nA] in FIG. 5.

[0059] The maximum value derivation unit 26 determines the maximum values ​​of graph SL in Figure 4, such as the second earliest one (approximately 100 [nA]), the third earliest one (approximately 120 [nA]), etc., and derives the loads associated with them (85 [W], 100 [W], etc.) (see graph SL in Figure 5).

[0060] It should be noted that the blood lactate level BL [mmol / l] in FIG. 5 is not measured by the lactate measuring device and lactate threshold deriving device 20 according to the embodiment of the present invention, but is a value measured by drawing blood.

[0061] The lactate threshold deriving unit 28 derives the lactate threshold of the subject based on the load at the change point where the rate of increase in the maximum value of the measurement result relative to the load changes to a decrease.

[0062] 5, the graph SL passes through points (70 [W], 92 [nA]), (85 [W], 100 [nA]), (100 [W], 120 [nA]), and (115 [W], 120 [nA]). The rate of increase of the maximum value [nA] with respect to the load [W] increases from (100-92) / (85-70) = 0.53 [nA / W] to (120-100) / (100-85) = 1.33 [nA / W], but decreases to (120-120) / (115-100) = 0 [nA / W] at the point (100 [W], 120 [nA]). That is, in the blood lactate level BL in FIG. 5, the change point at which the rate of increase in the maximum value relative to the load changes to a decrease is the point (100 [W], 120 [nA]).

[0063] The lactate threshold derivation unit 28 derives the lactate threshold LT of the subject based on the load (100 [W]) at the change point (100 [W], 120 [nA]).

[0064] For example, the lactate threshold derivation unit 28 determines the lactate threshold to be the load between the load (100 [W]) at the change point (100 [W], 120 [nA]) and the load (115 [W]) one cycle after the load at the change point (for example, 107.5 [W], the average of 100 [W] and 115 [W]).

[0065] It is common to define the lactate threshold LT as the load at which the blood lactate level BL measured by blood sampling is 2 [mmol / L], and in this case the lactate threshold LT is approximately 110 [W]. Therefore, the lactate threshold 107.5 [W] derived by the lactate threshold derivation unit 28 is approximately equal to the lactate threshold LT (110 [W]).

[0066] Fig. 6 is a diagram showing another example of the results derived by the maximum value derivation unit 26. As in Fig. 5, Fig. 6 also shows the amount of lactate in sweat (maximum value) SL [nA] and the amount of lactate in blood BL [mmol / L]. However, the amount of lactate in sweat (maximum value) SL [nA] in Fig. 6 corresponds to a measurement result other than that shown in the graph SL in Fig. 4.

[0067] Referring to FIG. 6, the change point is point (135 [W], 280 [nA]). The lactate threshold derivation unit 28 determines the load 135 [W] at the change point as the lactate threshold. On the other hand, it is common to determine the load at which the blood lactate level BL measured by blood sampling is 2 [mmol / L] as the lactate threshold LT. In this case, the lactate threshold LT is 135 [W]. Therefore, the lactate threshold 135 [W] derived by the lactate threshold derivation unit 28 matches the lactate threshold LT (135 [W]).

[0068] Next, the operation of the embodiment of the present invention will be described.

[0069] The lower part of the flow path 13 is open toward the skin 2 , and sweat secreted from the skin 2 enters the flow path 13 .

[0070] Here, PBS is sucked out from PBS supply unit 10 by pump 17, and is provided to inlet 13a via tube T0. The PBS further flows through flow path 13, washes away sweat secreted from skin 2 from skin 2, and heads toward outlet 13b together with the washed-away sweat. The PBS (containing sweat) that has headed toward outlet 13b is provided to inlet 14a of flow path 14 via tube T1, and flows through flow path 14.

[0071] Here, the electrodes CE, WE, and RE arranged in the flow path 14 cause the measuring device 16 to generate a current corresponding to the lactic acid in the sweat, and the concentration of lactic acid can be measured.

[0072] At the electrode WE, lactic acid is decomposed by an enzyme to produce hydrogen peroxide, which then undergoes a redox reaction to generate electrons. These electrons are injected into the carbon graphite in the carbon graphite layer (containing Prussian blue) of the electrode WE, with the Prussian blue acting as an electron mediator. These injected electrons then move to the electrode CE, causing a current to flow between the electrode CE and the electrode WE. However, electron injection by the Prussian blue layer requires a potential, and this potential (0 V) is provided by the electrode RE.

[0073] The PBS (containing sweat) that has flowed through the flow path 14 is given to the waste liquid reservoir 18 via the outlet 14b, the tube T2, the pump 17, and the tube T3, and is stored as waste liquid.

[0074] The measurement results of measuring device 16 are recorded in measurement result recording unit 22 in association with time (see graph SL in FIG. 4). The load applied to the subject is also recorded in load recording unit 24 in association with time (see 70 [W], 85 [W], ... in FIG. 4). Based on the contents recorded in measurement result recording unit 22 and load recording unit 24, maximum value derivation unit 26 derives the maximum value of the measurement results (for example, graph SL in FIG. 4) in association with the load (see graph SL in FIG. 5).

[0075] Furthermore, the lactate threshold deriving unit 28 derives the lactate threshold SL of the subject based on the load at the transition point (see FIG. 5) where the rate of increase of the maximum value relative to the load changes to a decrease. For example, the lactate threshold is determined to be the load between the load (100 W) at the transition point (100 W, 120 nA) and the load (115 W) one cycle after the load at the transition point (e.g., 107.5 W, the average of 100 W and 115 W) (see FIG. 5). Alternatively, the lactate threshold is determined to be the load of 135 W at the transition point (see FIG. 6).

[0076] According to an embodiment of the present invention, the lactate threshold can be accurately derived based on the measurement results of the lactate level in sweat.

[0077] In other words, if most of the lactic acid in sweat is lactic acid that has seeped out of the blood and dissolved into sweat, then at the lactate threshold, not only the lactic acid level in the blood but also the lactic acid level in the sweat would begin to rise. However, only a small amount of lactic acid in sweat is lactic acid that has seeped out of the blood and dissolved into sweat. Rather, it is thought that the majority of lactic acid in sweat is lactic acid produced by the exercise of the muscles that control sweating. For this reason, it is not necessarily the case that the lactic acid level in sweat begins to rise at the lactate threshold.

[0078] Here, the inventors of the present application have discovered through experiments (see, for example, Figures 5 and 6) that the amount of lactate in the blood increases near the load at which the rate of increase in the maximum value of the measurement results of lactate levels in sweat in response to the load applied to the subject changes to a decrease.

[0079] Based on this discovery, the lactate threshold SL of the subject is derived based on the load at the change point, so that the lactate threshold can be accurately derived based on the measurement results of the lactate level in sweat.

[0080] The following modifications of the embodiment of the present invention are possible.

[0081] <Modification> 7 is a functional block diagram showing the configuration of a lactate threshold derivation device 20 according to a modified embodiment of the present invention. The lactate threshold derivation device 20 according to the modified embodiment of the present invention includes a total derivation unit 27 instead of the local maximum value derivation unit 26 of the embodiment of the present invention.

[0082] The total deriving unit 27 derives the total of the measurement results around the time when the measurement result of the amount of lactate in the subject's sweat reaches a maximum value, in correspondence with the load. As with the case of the maximum value of the measurement result of lactate in sweat, the amount of lactate in the blood also increases around the load at the change point where the rate of increase in the total relative to the load applied to the subject changes to a decrease.

[0083] The lactate threshold deriving section 28 derives the lactate threshold of the subject based on the load at the change point where the total rate of increase in the load applied to the subject changes to a decrease.

[0084] The above embodiment can also be realized as follows: A computer equipped with a CPU, hard disk, and media (USB memory, CD-ROM, etc.) reader reads media containing programs for implementing the above-mentioned components, such as measurement result recording unit 22, load recording unit 24, maximum value deriving unit 26, total deriving unit 27, and lactate threshold deriving unit 28, and the media is installed on the hard disk. The above functions can also be realized in this manner. [Explanation of symbols]

[0085] 20 Lactate threshold derivation device 22 Measurement result recording section 24 Load Recording Section 26 Maximum value derivation part 27 Total Derivation Section 28 Lactate threshold derivation section 10 PBS supply section 14 Flow path 13a, 14a inlet 13b, 14b outlet 130, 140 board 16 Measuring instruments 17 Pump 18 Waste liquid storage section CE, WE, RE electrodes T0, T1, T2, T3 tubes

Claims

1. a measurement result recording unit that records the measurement results of the amount of lactic acid in the subject's sweat in association with time; a load recording unit that records the load applied to the subject in association with time; a maximum value deriving unit that derives a maximum value of the measurement result in association with the load; a lactate threshold deriving unit that derives the lactate threshold of the subject based on the load at a change point where the rate of increase of the maximum value relative to the load changes to a decrease; Equipped with the load is a load during exercise when a cycle of warm-up exercise, exercise, and rest is repeated multiple times by the subject, The load increases with each cycle. Lactate threshold derivation device.

2. a measurement result recording unit that records the measurement results of the amount of lactic acid in the subject's sweat in association with time; a load recording unit that records the load applied to the subject in association with time; a sum derivation unit that derives a sum of the measurement results in the vicinity of a time when the measurement result takes a maximum value, in association with the load; a lactate threshold deriving unit that derives the lactate threshold of the subject based on the load at a change point where the total increase rate relative to the load changes to a decrease; Equipped with the load is a load during exercise when a cycle of warm-up exercise, exercise, and rest is repeated multiple times by the subject, The load increases with each cycle. Lactate threshold derivation device.

3. 3. The lactate threshold calculation device according to claim 1, The lactate threshold derivation unit determines the load at the change point as the lactate threshold. Lactate threshold derivation device.

4. 3. The lactate threshold calculation device according to claim 1, the lactate threshold derivation unit determines the lactate threshold as a load between the load at the change point and the load one cycle after the load at the change point. Lactate threshold derivation device.

5. 3. The lactate threshold calculation device according to claim 1, The warm-up exercise is performed for a predetermined time at a predetermined heart rate of the subject. Lactate threshold derivation device.

6. 3. The lactate threshold calculation device according to claim 1, The rest period is longer than the exercise period. Lactate threshold derivation device.

7. a measurement result recording step of recording the measurement result of the amount of lactic acid in the sweat of the subject in correspondence with time; a load recording step of recording the load applied to the subject in relation to time; a maximum value deriving step of deriving a maximum value of the measurement result in association with the load; a lactate threshold deriving step of deriving the lactate threshold of the subject based on the load at a change point where the rate of increase of the maximum value relative to the load changes to a decrease; Equipped with the load is a load during exercise when a cycle of warm-up exercise, exercise, and rest is repeated multiple times by the subject, The load increases with each cycle. Lactate threshold derivation method.

8. a measurement result recording step of recording the measurement result of the amount of lactic acid in the sweat of the subject in correspondence with time; a load recording step of recording the load applied to the subject in relation to time; a sum deriving step of deriving a sum of the measurement results in the vicinity of the time when the measurement result takes a maximum value in association with the load; a lactate threshold deriving step of deriving the lactate threshold of the subject based on the load at a change point where the total increase rate relative to the load changes to a decrease; Equipped with the load is a load during exercise when a cycle of warm-up exercise, exercise, and rest is repeated multiple times by the subject, The load increases with each cycle. Lactate threshold derivation method.

9. A program for causing a computer to execute a lactate threshold derivation process, The lactate threshold derivation process a measurement result recording step of recording the measurement result of the amount of lactic acid in the sweat of the subject in correspondence with time; a load recording step of recording the load applied to the subject in relation to time; a maximum value deriving step of deriving a maximum value of the measurement result in association with the load; a lactate threshold deriving step of deriving the lactate threshold of the subject based on the load at a change point where the rate of increase of the maximum value relative to the load changes to a decrease; Equipped with the load is a load during exercise when a cycle of warm-up exercise, exercise, and rest is repeated multiple times by the subject, The load increases with each cycle. program.

10. A program for causing a computer to execute a lactate threshold derivation process, The lactate threshold derivation process a measurement result recording step of recording the measurement result of the amount of lactic acid in the sweat of the subject in correspondence with time; a load recording step of recording the load applied to the subject in relation to time; a sum deriving step of deriving a sum of the measurement results in the vicinity of the time when the measurement result takes a maximum value in association with the load; a lactate threshold deriving step of deriving the lactate threshold of the subject based on the load at a change point where the total increase rate relative to the load changes to a decrease; Equipped with the load is a load during exercise when a cycle of warm-up exercise, exercise, and rest is repeated multiple times by the subject, The load increases with each cycle. program.

11. A computer-readable recording medium having a program recorded thereon for causing a computer to execute a lactate threshold derivation process, The lactate threshold derivation process a measurement result recording step of recording the measurement result of the amount of lactic acid in the sweat of the subject in correspondence with time; a load recording step of recording the load applied to the subject in relation to time; a maximum value deriving step of deriving a maximum value of the measurement result in association with the load; a lactate threshold deriving step of deriving the lactate threshold of the subject based on the load at a change point where the rate of increase of the maximum value relative to the load changes to a decrease; Equipped with the load is a load during exercise when a cycle of warm-up exercise, exercise, and rest is repeated multiple times by the subject, The load increases with each cycle. Recording medium.

12. A computer-readable recording medium having a program recorded thereon for causing a computer to execute a lactate threshold derivation process, The lactate threshold derivation process a measurement result recording step of recording the measurement result of the amount of lactic acid in the sweat of the subject in correspondence with time; a load recording step of recording the load applied to the subject in relation to time; a sum deriving step of deriving a sum of the measurement results in the vicinity of the time when the measurement result takes a maximum value in association with the load; a lactate threshold deriving step of deriving the lactate threshold of the subject based on the load at a change point where the total increase rate relative to the load changes to a decrease; Equipped with the load is a load during exercise when a cycle of warm-up exercise, exercise, and rest is repeated multiple times by the subject, The load increases with each cycle. Recording medium.

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