FR2678158A1 - Method and apparatus for optimising the pulse during endurance exercise - Google Patents

Abstract

Apparatus harnessing the principle of biofeedback in order quickly to minimise the overhigh pulse of an untrained subject as compared with an athlete. It includes earphones 70 for exhibiting tone pulses in the rhythm of the heart, originating from a modulated generator 50 and a reference generator 60. The modulated pitch measures the present pulse, by virtue of a control unit 40 initialised by a shaper 30 triggered by the R-ECG wave conditioned by an acquisition unit 20. The reference pitch can be readjusted downwards between tests, with the aid of a pulse monitor 80.

Description

METHOD AND APPARATUS FOR OPTIMIZING THE PULSE
DURING THE ENDURANCE EXERCISE
The present invention relates to a method and apparatus for optimizing the heart rate during para-sport endurance exercise for the purpose of cardiovascular maintenance, prevention or rehabilitation.

In normal non-trained endurance exercise spontaneous vago-sympathetic balance determines a supra-optimal pulse. On the other hand, in athletes the regulation of the heart is optimized during years of training in the sense of maximum cardiac output at the slightest cardiovascular stress - a compromise arbitrated by the intensity and duration of the effort - which makes possible the performance in endurance events. This compromise combines increased ventricular contractility ensuring more complete emptying - sympathetic obedience - with a pulse growth - similarly obddience - moderate thanks to the maintenance of a certain vagal tone, which ensures less incomplete filling of the ventricles. in short, the manifestly lower pulse during effort associated with resting bradycardia constitutes the "signature" of the supranormal vagal tone of the athletic heart (see on this subject: Blume G., "Ergometry with cyclo-ergometer",
Electromedica, 1975r no. 1, pp. 22-29). Moreover, an accentuated vagal tone is considered a sign of cardiac youth and the most important single factor of positive prognosis in myocardial suffering (see in this regard: Eckberg DL,
Parasympathetic cardiovascular control in human disease: a critical review of methods and results, Am. J. Physiol., 198 O, vol. 239, pp. H581-H593).

Recent research on pulse stabilization
under mental strain suggested the educability of the vagal tone of the heart thanks to the development in men of associations
interneuronal cort # co-bulbar, still of the contingent type (see: Negoescu R., Csiki IE, Autonomic control of the heart in
some vagal maneuvers and normal sleep, Phvsioloav lBucharest).

1989, vol. 26, pp. 39-49; Negoescu R., Csiki I.E., Interaction of heart rate control menus under postural, mental and vagal interventions, Proc. 12th Ann. Int. Conf. IEEE-EMBS, 1990, vol.

12, pp. 833-834). Biofeedback techniques - making take
awareness, for the purpose of voluntary control, of physiological signals normally outside the range of the senses - are the main aids in conscious self-manipulation of the pulse.

In the light above, the vagal agitation of this influence
conscious appears particularly clear in effort, when the
sympathetic tone is subject to neuro-hormonal automatism
inexorable, metabolic mechanism.

These are Goldstein et al. who first demonstrated in the laboratory that the pulse can be lowered by means of the
biofeedback during moderate endurance exercise - brisk walking
the treadmill (Goldstein DS et al., Biofeedback heart rate
training during exercise, Biofeedback and Self-Recxulationt 1977,
flight. 2, pp. 107-125). In replying to them, Perski and Engel did not
only confirmed these results for exercise on a bicycle but their data show that the subjects in the group
experimental with biofeedback were better adapted to the effort and less subject to fatigue than their colleagues in the control group practicing the same exercise without biofedback (Perski A., Engel B.

T., Biofeed. Self-Req. 1980, vol. 5, pp. 91-104). These latter authors note that "the cardiac changes observed during this study (10 - 15 days), are comparable to the changes obtained after 2 - 3 months of conventional training".

 At the present time, however, to our knowledge, there are no protocols expressly designed to optimize down the pulse of para-sportsmen by means of biofeedback during autonomous endurance exercise in a natural environment, such as biking, running, canoeing. Accelerated induction of the cardiovascular adaptive state which has an impact on performance and tolerance (or pleasure) of effort in the immediate future, and on the acquisition of athletic bradycardia in a significantly shorter period than by conventional training - constitutes the reasonable aim, seen above, of such a protocol.

 With regard to cardiotachometric biofeedback techniques (concerning the heart rate) in the laboratory, most of them resort to visual modality to provide information on the pulse beat by beat of the patient (see, for example, all in Biofeedback and Self-Requlation, Perski and Engel 1980, vol.

5, pp. 91-104; Goldstein et al., 1977, vol. 2, pp. 107-125;
Blanchard et al., 1976, vol. 2, pp. 81-91, DeGood and Adam, 1976, voîl, pp. 373-385; Manuck, 1976, vol. 1, pp. 273-284) and sometimes on a reference level allowing the subject to better situate himself (for example Perski and Engel, 1980, op. Cit.).

However, this method of biofeedback does not lend itself to natural exercise when visual attention vis-à-vis the cycle route of the public road or on the sometimes accidental course of running is quite solicited. Hearing modality, which is more rare, usually takes the form of a "beep" type pulse in a fixed tone, at a heart rate (see, for example,
Stern and Elder, Biofeed. Self-Rea. 1982, vol. 7, pp. 53-69;
Bergman and Johnson, PsychoDhysiology, 1972, vol. 9, pp. 30-39); reference is made, still in experimental laboratory research, to the tone of a height proportional to the instantaneous pulse and of a duration equal to the current interbeat interval (Blanchard and Young, Journal of General Psycholoqv. 1972, vol. 87 , 195-202) is fixed and short (tone-pulse, see for example Shapiro et al., Psvchosomatic Medicine, 1970, vol. 32, pp. 417-432).

Finally, commercial equipment offers biofeedback either visual of the digital type (the interbeat interval converted into beats per minute - beats / min - and the result displayed), or auditory of the beep type with fixed tone, but has a size and weight unsuitable for being quickly " forgotten "by the subject as a physical inconvenience, although this apparatus is conventionally portable (see, for example, TEMP / SC 200T described in: Biofeedback and Self Requlation 1987, vol. 12, p. 335). A "cardiac monitor" recently distributed in
France (Technical notice, Elexis - Pulsmeter Super 1000,
Chapak, Nimes, 1991) fulfills this condition of micro-portabllit # while emitting an audible warning at each crossing of the lower or higher pulse threshold of the optimal, pre-established training deviation; although it is capable of continuously displaying the pulse on a # notch-watch on the wrist or even of delivering audible beeps to the heartbeat by the me # shows me, this device is, obviously, insufficiently equipped to provide feedback continuous cardiotachometric effective on a subject in full effort, under visual constraint and threshold of auditory perception sometimes high.

 In what follows the terms pulse by beat, instantaneous pulse and instantaneous frequency are equivalent by designating the inverse of an interbeat interval (or RR interval), by difference from the term mean (or averaged) pulse, designating the average number heartbeat [over a certain period of time, even if the unit of measurement is the same: beats / min.

 The method according to the invention makes it possible to fill the gap and remedy the above drawbacks by the fact that, according to a first characteristic, a conventional endurance test of an intensity / duration in accordance with the habits of the subject or with his physical condition. general is established and the pulse monitored telemetrically; then a standard endurance test with a cycloergometer is established in accordance with the data previously collected; based on these tests we establish the difference in the average pulse of the subject under examination vis-à-vis the average pulse of the performance sportsman subjected to the same effort, according to the literature data; this difference will be erased in stages by a series of biofeedback assisted workouts as follows.

 The method and apparatus according to the invention, according to a second characteristic, present to the subject in autonomous endurance exercise, via stereophonic headphones, on the one hand a pulse-tone in heart rate, the pitch of this tone being proportional to the instantaneous frequency of the immediately preceding cardiac cycle, and on the other hand a pulse-tone at the same rate whose height is constant and represents the reference pulse to be reached and maintained during the session-stage In progress.

 The apparatus according to the invention, according to a third characteristic, uses a beat counter and a watch for a post hoc comparison between the average pulse reached during the exercise and the pulse programmed as a reference; the magnitude of the difference determines the benchmark adjustment for the next session.

According to particular embodiments of the apparatus according to the invention:
- the calculation of the instantaneous frequency of the cardiac cycle can be carried out, at a multiplying factor of ten, by controlling the frequency of oscillation of a conventional astable circuit during the plateau of a trapezoidal pulse, the front of which is the shape of a non-linear #air ramp, has developed along the RR interval justly concluded ;;
- the generation of the trapezoidal pulse can be carried out using an analog logic with additional transistors around a low loss memory capacitor, comprising a load / store transistor, a read / change level transistor and a transistor for rapid unloading (resetting) of a duration defined by a conventional stable mono circuit;
the tones applied to the stereophonic headphones can be generated directly using the two conventional astable circuits whose oscillation frequencies are controlled by the instantaneous frequency of the last cardiac cycle by means of the trapezoidal pulse described above on the one hand and by a potentiometric adjustment establishing the reference tone on the other hand ;;
- the display in beats / minute of the current instantaneous pulse or the reference pulse (depending on the position of a channel selector) can be achieved using two conventional cascade circuits: a divider and a counter / display three decades, starting from the oscillations provided by the generators described above;
- a single rectangular pulse triggered by the R wave of the ECG signal can lead to the sequence of analog and digital functions described above, namely: the initialization of the trapezoidal pulse level, the authorization of the oscillation of the two tone generators, zero cycling (reset) St start (account) - stop (poster) of the divider / counter / display block; in addition this pulse can trigger the advance of one unit of the beat counter.

 The accompanying drawings illustrate the invention.

 FIG. 1 illustrates the instrumental part of the method in the form of the block diagram of the apparatus according to the invention.

 FIG. 2 represents a combined block / principle diagram, the principle details having to illustrate an embodiment of the apparatus according to the invention.

 FIG. 3 represents a diagram of the signals relating to an embodiment of the apparatus according to the invention.

 FIG. 4 represents an adjustment diagram of the block for calculating the instantaneous frequency, relating to an embodiment of the apparatus according to the invention.

With reference to these drawings, the apparatus according to the invention comprises, at the level of the block diagram of FIG. 1, an acquisition module 20 intended for amplifying the ECG signal collected by exercise electrodes in a thoracic bypass and also for conditioning the signal to reliably separate the R wave from the ECG trace. The training block 30 ensures the generation of a rectangular pulse triggered by the spike of the R wave. This pulse initializes the control block 40 responsible for modulating the oscillation frequency of the generator 50 in such a way that it is the multiple of ten of the instantaneous frequency in beats / min of the cardiac cycle last concluded. The same initialization pulse authorizes the oscillation of the modulated generator 50 above and of the reference generator 60 whose fixed oscillation frequency is
adjustable from one training session to the next. The two generators feed into the stereophonic headphones 70 allowing the subject to compare at the end of each cardiac cycle his instantaneous pulse with the reference-model at
achieve, in the form of short tones of different height; a system of cardiotachometric feedback with double synergistic proportionality is thus implemented: by the cadence of the tones relating to the duration of the cardiac cycles (distributed information) and by the height of the tone relating to the instantaneous heart rate (concentrated information). Block 80 monitors the effective pulse (in the normal position of a selector) or the reference pulse (during the development prior to the session). The counter / watch 90 takes stock of the total number of beats and the duration in minutes of the session, whose ratio is the average pulse during the exercise, to be compared to the reference pulse in order to establish the adjustment of the reference for the following session.

 In the presentation constructed around FIG. 2 to detail a preferred embodiment of the apparatus according to the invention, the elements T are bipolar silicon transistors, D are silicon signal diodes, while R are resistors - all of low power. The combined diagram in fig 2 must also be examined with reference to the signal diagram - fig. 3. In this embodiment the supply voltage Vcc is 5 V, the duration of the initialization pulse is 200 ms and the duration of the unloading pulse is 40 ms.

The shaping function is accomplished in fig. 2A by a
mono stable conventional circuit, the 1st half of a circuit
built-in double monostable type 74123, which provides a rectangular pulse with multiple functionality:
initialization of the counter block, authorization of the generators,
cycling the pulse monitor, advancing the beat counter.

The control block has in fig. 28 A
memory capacitor C4 tantalum, cycle by trapezoidal signal
as follows: a) storage over the pulse duration
initialization of a plateau potential dependent on the immediately preceding RR interval; b) rapid unloading using T42 and R45 controlled by the unloading pulse
supplied by a stable mono circuit 41 - the 2nd half of the integrated circuit of type 74123 - triggered in turn by the posterior front of the initialization pulse; c) non-linear ramp loading using the constant current generator
T41-R41-R43-R44 damped by the D41-R42 group, the semi-adjustable resistors R41 and R42 used to develop the linear relationship between the instantaneous heart rate in beats / min and the height of the controlled tone, conform # in the adjustment diagram of fig. 4. Finally, the reading of the stage potential and its location in the quasi-linear frequency modulation range of the slave tone generator are carried out by the elements T43, R46, D42, D43.

The generators 51 and 61 of FIGS. 2 B, C are identical astable circuits, except the control of the oscillation frequency from the control block for the 51 and a potentiometric adjustment for the 61; they are developed from a double monolithic time base of type 556 to provide
relaxation oscillations of a filling factor close to
50%, which are sent directly to planned stereo headphones with individual volume control
The pulse monitor 80 of fig. 2C includes a divider by 2 and a 3-decade counter / display which reconstitutes the instantaneous pulse in beats / min after the authorization of the generators to
200 ms will have completed a first division by 5.

 The 5-decade totalizing beat counter and the 4-digit solidarity watch (100 min) are started and stopped manually by zero & start - stop, start and end of the training session.

 As a non-limiting example, it is presented the case of an adult of 40 years, without cardiovascular complaints and not particularly active (rare episodes of jogging in the anamnesis), who in preliminary test realizes on a circular course slightly wavy 4.2 km a time of 31 min against an average pulse of 125 bat / min. The cycloergometer test indicates, for the same pulse profile, a power output of 100 W. The optimal pulse of the athlete for the same power is 95 beats / min (see Blume G., 1975, op. Cit. ). For the first "cardio-active" biofeedback training session, he is offered the reference of 110 bpm, which he approaches at 120 bpm.

Biofeedback is implemented by the preferred embodiment of the device according to the invention, being presented as two micro-modules of 50 g each attached to the support of the headphones. The subject is instructed to try to approach as much as possible the variable tone - witness of his pulse, of the reference tone - the athletic ideal, while preserving his usual rhythm of the race;
for this purpose any suitable strategy within the
breathing style, mental imagery or, simply, "focus" on moderating the pulse is allowed.

 At the end of 5 sessions under the same reference, the subject descends to 1116 beats / min and his journey time decreases to 29 min, which determines the adjustment of the reference to 106 beats / min. A session takes place without biofeedback and, nevertheless, the average pulse is maintained at 120 beats / min (the so-called transfer). After 1 month of cardio-active training at the rate of 4 sessions per week, the average pulse stabilizes at 104 beats / min, against a reference already at 95 beats / min.

The synthetic cross-country effort index (average speed
* distance traveled) progresses in the meantime from 34.1 to 42.3 km * km / h corresponding to a journey time of 25 min, while the basal pulse (averaged over 3 minutes of rest in clinostatism) evolves from 67 at 63 bpm.

A control subject of comparable age and state of training, A
assuming the same race program but without assistance from
biofeedback, shows the following progression: average pulse
120--> 116 bat / min; journey time: 30--> 28 min; effort index:
35.3--> 37.8 km * km / h; basal pulse: 66 bpm stationary.

Thus, the method and the apparatus according to the invention distill
knowledge acquired through research in experimental psychophysiology, using a biomedical engineering development, a practical means - that is to say simple, of an autonomous exploitation after an assisted implementation, usable in the
majority of endurance exercises in their natural environment - to make it more effective, from the point of view of
maintenance, prevention or rehabilitation
cardiovascular, physical and psychic effort of "runners
for health ", more and more numerous.

Claims (6)

 #) A # parell to optimize the pulse during the endurance exercise characterized in that it includes a conventional endurance test and a standardized test with a cycloergometer to objectify the excess of the average pulse of the non-entrained subject vis- vis-à-vis the athlete's optimal pulse; this excess is then minimized by stages of autonomous training in natural conditions under cardiotachometric biofeedback comprising the application by means of stereophonic headphones of a part of a pulse-tone in heart rate, the height of this tone being proportional at the instantaneous frequency of the immediately preceding cardiac cycle, and on the other hand a pulse-tone at the same rhythm whose height is fixed, representing the reference pulse to be reached; according to the success of the subject to have approached his average pulse, account at the end of a stage, of the reference pulse, the said reference is adjusted down for the next stage.  2) Apparatus according to claim 1 characterized in that the calculation of the instantaneous frequency of the cardiac cycle is carried out, to a multiplying factor of ten, by controlling the oscillation frequency of a conventional astable circuit 51 during the plateau d '' a trapezoidal pulse whose forehead  anterior to the form of a non-linear ramp developed along the RR interval justly concluded.  3) Apparatus according to claim 1 or claim 2  characterized in that the generation of the trapezoidal pulse  is carried out using analog logic with complementary transistors around a low loss memory capacitor C4, comprising a load / store transistor T41, a read / change level transistor T43 and a transistor T42 for rapid unloading (reset) of a duration defined by a conventional stable mono circuit 41.  4) Apparatus according to claims 1, 2 and 3 characterized in that the tones applied to stereophonic headphones 70 are generated using two conventional astable circuits 51 and 61 whose oscillation frequencies are controlled by the instantaneous frequency of the last cardiac cycle by means of the trapezoidal pulse according to claim 2 on the one hand, and by a potentiometric adjustment on the other hand.  5) Apparatus according to claims 1, 2, 3, and 4 characterized in that the display in beats / minute of the current instantaneous pulse or the reference pulse (depending on the position of a channel selector) is achieved at using two conventional cascade circuits 80: a divider and a counter / display with three decades, starting from the oscillations provided by the generators 51 and 61 according to claim 4.  6) Apparatus according to claims 1, 2, 3, 4 and 5 characterized in that a single rectangular pulse triggered by the R wave of the ECG signal leads the chain of analog and digital functions according to claims 2, 3, 4 , and 5, namely: the initialization of the trapezoidal pulse level according to claim 2, the authorization of the oscillation of the two tone generators 51 and 61, the zero cycling (reset) & start ( account) - stop (poster) of the divider / counter / display block 80 and the advance of one unit of the beat counter 90.