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NR 49 AN TRO PO MO TO RY KA 2010 A SIMPLE METHOD OF ASSESSMENT OF ENERGY EXPENDITURE OF LOW-IMPACT AEROBIC EXERCISES PROSTA OCENA WYDATKU ENERGETYCZNEGO AEROBIKU TYPU LOW-IMPACT Wanda Pilch*, Łukasz Tota**, Szczepan Wiecha**, Dorota Ambroży*** *** Dr, Physiology and Biochemistry Unit, Institute of Human Physiology, University School of Physical Education, Cracow, Poland *** MSc, Physiology and Biochemistry Unit, Institute of Human Physiology, University School of Physical Education, Cracow, Poland *** Dr, Theory and Methodology of Gymnastics Department, University School of Physical Education, Cracow, Poland Key words: aerobic, energetic expenditure, heart rate Słowa kluczowe: aerobik, wydatek energetyczny, częstość skurczów serca SUMMARY • STRESZCZENIE Cel pracy. Określenie charakteru i intensywności wysiłku, a także wydatku energetycznego poniesionego przez młode kobiety podczas godzinnych zajęć aerobiku typu low-impact. Materiał i metody. Przeprowadzono ocenę możliwości wysiłkowych badanych 10 kobiet oraz progowych wielkości wskaźników fizjologicznych określających adaptację organizmu do wysiłku. Przeprowadzono na bieżni laboratoryjny test wysiłkowy ze stopniowo narastającym obciążeniem, wykonywany do odmowy. W trakcie testu . oznaczano m.in. maksymalny rytm pracy serca (HR) oraz maksymalne pochłanianie tlenu (VO2 max). W drugim etapie obserwowano dynamikę zmian HR w czasie godzinnych zajęć aerobiku, stosując w tym celu sporttestery firmy Polar Electro. W celu oznaczenia wydatku energetycznego posłużono się metodą kalorymetrii pośredniej, która polega na pomiarze minutowego poboru tlenu w trakcie ocenianego wysiłku. Znając równoważnik kaloryczny, który dla jednego litra tlenu odpowiada 5 kcal wydatkowanej energii, możliwe jest wyrażenie wydatku energetycznego poniesionego przez badane kobiety podczas zajęć aerobiku w kcal. Wyniki i wnioski. Na podstawie przeprowadzonych pomiarów i porównań stwierdzono, że wydatek energetyczny o średniej wartości 308, jaki podczas godzinnych zajęć z aerobiku low-impact poniosły młode kobiety o średniej wysokości, przeciętnej masie ciała oraz małym otłuszczeniu, można zaliczyć do pracy lekkiej. - - - - - Aim of the work. Estimating the character, intensity and energy expenditure in young women during one hour of aerobic low-impact training. Material and methods. The exercise ability of ten women was measured as well as threshold physiological parameters, which determine adaptation of the organism to the physical strain. The exercise test on the laboratory track was performed until subject’s refusal. During the test maximal heart rate (HR) and maximal . oxygen consumption (VO2 max) were measured. In the second stage of the study, during one hour of aerobics exercises, the dynamic changes of HR were observed using the sport-testers produced by Polar Electro Corporation. To estimate energy expenditure indirect calorimetric method was used. To use this method, one minute absorption of oxygen has to be measured, than by knowing caloric equivalent (which is 5 kcal for one liter of oxygen) it is possible to measure the energy output in women during aerobic. Results and conclusions. According to energy expenditure during one hour of aerobics low-impact (308 kcal) it may be classified as light work. – 89 – Wanda Pilch, Łukasz Tota, Szczepan Wiecha, Dorota Ambroży - - - - - Introduction The modern kind of aerobics involves the whole body, and the correctly performed exercises increase the level of one’s physical fitness as well as tolerance to exertion. The term "exertion abilities" means the unit of the psychophysical properties of the body which enable the performance of certain exercises connected with the physical load; the term ‘exertion tolerance’ determines the body’s ability to perform the physical work from the moment the discomfort appears to the moment when the need to interrupt occurs. Aerobics is a system of physical exercises including the intensity, which require the big amount of oxygen to be delivered to a certain body. Looking at the intensity of aerobic, we can divide it into three parts: low-impact, hi-lo, hi-impact. These exercises enable the increase in exertion abilities as a result of fitness and health training, based on the intense oxygen exchange. The modern aerobics is the strict co-ordination of the movement with music in time and space. Consecutive exercises should form harmony together with the music which, like dance, is a unique experience including movement for both the instructor and the participants of the classes. Depending on the intended intensity of the exercises we use different melodies. There are two increasing and two decreasing phrases (depending on the pitch of the sound a phrase ends with) which are alternatively arranged in the musical theme. The phrase corresponds to a choreographical figure of eight (sequence), whereas the musical theme corresponds to a choreographic block [1]. The pace also changes depending on the advancement level of the group [2]. In the low-impact system, warming, strengthening, and calming elements can be distinguished I. Warming exercises: their aim is to prepare body for more intense exercises in the main aerobics part. In this part we use basic steps repeated many times. Duration is about 5–10 min. II. Main part, strengthening part. This part is constructed from a sequence of movement combined into blocks. The aim of this part is to maintain constant pulse using different choreography. Duration is about 30–40 min. III. Calming: we use some stretching exercises to calm down and relax the body. The high frequency of the systoles results in a substantial energetic effort and it increases the level of physical fitness. The efficiency of circulatory systems and respiratory systems is considered to be the most important element of one’s fitness which promotes health. An improvement in the cardiopulmonary function is conductive to the reduction of many cardiovascular diseases; it also enhances the ability to work and facilitates the opposition to tiredness [3]. Cardiopulmonary fitness is the ability of the system to deliver oxygen in amounts which are essential for taking up effective muscular work and prolonged physical activities. The efficient functioning of cardiopulmonary system is important for delivering oxygen and nutritional substances and removing unnecessary products of metabolism [4]. The aim of the research was to determine the character and intensity of the exertion as well as energy expenditure among young women during an one-hour long low-impact aerobics classes. Methodology of the research 10 women leading an active way of life took part in the research. Their anthropometrical indicators fitted in the range for thin women aged 21–23 – Tab. 1 [5, 6]. Technology of performed measurements The research was carried out in a gym and a physical research classroom of Chair of Physiology and Biochemistry at University School of Physical Education in Cracow. The program of the research included 2 types of tests: a laboratory exertion test in which the load has gradually increased until the moment of the subjective feeling of inability to continue workout, as well as HR observation during aerobics exercises in the gym. Before the research was carried out, the basic biometrical parameters had been measured. The height of the bodies was measured by means of an anthropometre, whereas the mass of the bodies was taken with the help of an electronic scale Tanita, made in Japan. The test started with 2-minutes long warm-up on a mechanical track with the speed of 6 km/h. The speed of the track’s movements was increased 1 km/h every 2 consecutive minutes. During the exertion, the frequencies of the systoles (HR) and the respiratory parameters such as V̇O2 (ml/kg), V̇O2 (l/min) were recorded. After finishing the exertion, parameters were also measured during 3 minutes of repose. The second type of the research, the low-impact aerobics exercises, lasted for 70 minutes and the following stages could be distinguished: – 90 – A simple method of assessment of energy expenditure of low-impact aerobic exercises III stage – 10 minutes, (warm-up – simple exercises based on elementary steps), III stage – 40 minutes, (choreographic routine), III stage – 15 minutes, (weight training of basic muscular groups), IV stage – 5 minutes, (relaxation part, stretching). The dynamics of changes in the frequency of the systoles was measured with a versatile device Acurex plus by Finnish company Polar-Electro. Microcomputers (sport-testers) make it possible to constantly monitor the heart’s work during each exertion. In the present research, the microcomputers were used during both track-tests and aerobics classes. A computer program enabling the current monitoring of the results from a device by the Finnish company Medicro OY had been applied in the registration and analysis of the respiratory data. This device registers the respiratory parameters. The heart’s work was monitored, its average size at different phases of exercising was calculated and identical HR values during the tracktest were compared in order to estimate the burning of calories from aerobics classes. The corresponding V̇O2 values were also recorded and they were subsequently accepted as adequate to the performed workout during 4 stages of aerobics. The time of individual phases as well as the adequate level of V̇O2 made it possible to estimate the global use of oxygen and, consequently, the energy expenditure as well. It was also demonstrated how the marked V̇O2 values and HR measured during aerobics classes were shaped in relation to the maximum values. In this way, the values of the measured parameters among the participants of the research and their potential abilities were received and presented. The material included in this research is represented by the results of 10 women – students of University School of Physical Education in Cracow who lead an active way of life most of the time. The average age of women taking part in the research amounted to 22.5 years, the height – 166.5 cm, whereas the body’s mass – 55.5 kg (Table 1). Results The frequency of the systoles (HR) during aerobics classes made it possible to trace the dynamics of changes of the heart’s work in particular stages of exertion. The biggest difference in the heart’s rhythm was recorded during the second part of aerobics classes (choreographic routine) in which the average HR count amounted to 143.6 beats per minute. The highest heartbeat at this stage was 192 beats per minute, whereas the lowest equalled 106 beats per minute (Table 2). The lower intensity was observed in parts I and II of aerobics classes (warm-up and physical exercises) No. Age Body height [cm] Body mass [kg] FAT [%] 1 24 177 56 25.0 2 22 160 49 20.5 3 23 176 59 24.5 4 22 163 60 33.5 5 25 170 64 30.0 6 22 159 49 21.5 7 21 168 50 21.5 8 22 162 55 26.5 9 22 158 45 17.0 10 22 172 68 38.0 x 22.5 166.5 55.5 25.8 SD 1.18 7.06 6.42 6.42 - - - - - Table 1. Somatic characteristics of the group – 91 – Wanda Pilch, Łukasz Tota, Szczepan Wiecha, Dorota Ambroży Table 2. The average frequency of heart rate in different parts of the aerobic I part No. II part III part IV part max min max min max min max min 1 155 74 184 131 165 110 161 100 2 155 63 174 129 172 110 133 107 3 148 99 177 116 159 110 148 107 4 151 104 165 120 146 101 146 107 5 141 81 173 108 134 84 112 91 6 142 94 166 106 167 88 127 94 7 122 97 167 109 159 92 120 80 8 176 110 192 145 183 115 145 118 9 142 74 166 110 136 96 119 92 10 151 107 155 110 133 97 110 85 x 148,3 90,3 171,9 118,4 155,4 100,2 132,1 98,1 SD 13,74 16,16 10,58 12,81 17,36 10,70 17,27 11,74 in which the lowest average heart count totalled 111.3 beats per minute and 107.3 beats per minute, whereas the highest average HR count amounted to 142.9 beats per minute (Table 2). During the graded track test, the maximum values of the heart’s systoles and the minute consumption of oxygen in global and relative frames were determined; the time of the race and the run distance were registered. The highest relative value VO2 max equaled 50.0 ml/kg/min, whereas the lowest totalled 39.5 ml/kg/min. The average count of the examined group was 45.4 ml/ kg/min. (Table 3). Table 3. The maximal oxygen consumption and heart rate, time and distance during maximal aerobic test on a treadmill V̇O2 max [ml/kg/ min] V̇O2 max [l/min] HRmax [sk/min] Time of run [min] Distance [m] 1 50.0 2.8 209 16.9 2496 2 45.2 2.47 198 15.0 2350 3 44.2 2.57 194 16.3 2407 4 39.8 2.66 205 15.1 2353 5 39.5 2.58 199 14.0 2140 6 46.4 2.43 187 12.5 1825 7 49.4 2.64 199 15.0 2357 8 47.3 2.73 215 15.6 2466 9 48.5 2.50 187 15.0 2343 10 43.5 3.11 197 15.5 2455 x 45.38 2.65 199 15.09 2319.2 SD 3.7 0.19 8.88 1.20 199.83 - - - - - No. – 92 – A simple method of assessment of energy expenditure of low-impact aerobic exercises Table 4. Comparison of heart rate on each stage of aerobics with the results obtained a speed run on a treadmill. HR [1/min] V [km/h] No. HRmax HR1 HR2 HR3 HR4 V1 V2 V3 V4 1 128.3 151.4 135.7 129.5 6.5 7.0 6.5 6.5 209 2 111.3 157.1 131.8 121.0 6.5 8.0 7.0 6.5 198 3 130.2 149.4 133.0 117.4 8.0 9.0 8.0 6.0 194 4 130.6 140.0 124.1 125.5 6.5 7.0 6.5 6.5 205 5 122.1 133.4 109.1 102.0 6.5 6.5 6.0 6.0 199 6 127.8 141.1 121.2 115.7 6.5 7.5 6.5 6.5 187 7 117.9 133.9 121.3 104.3 6.5 7.0 6.5 6.0 199 8 142.9 164.4 142.0 129.3 7.5 8.5 7.5 6.5 215 9 109.7 132.9 107.3 104.3 6.5 7.5 6.0 6.0 187 10 131.3 132.2 118.6 94.5 7.0 7.0 6.5 6.0 197 x 125.2 143.5 124.4 114.3 6.8 7.5 6.7 6.29 199 SD 10.9 11.40 11.28 12.37 0.53 0.78 0.63 0.26 8.88 The average values of the heart’s systoles’ frequency calculated from 70-minute low-impact fitness classes are close to those received during the graded test with the race speed of 7 km/h (Table 4). To determine the difficulty of the work carried out by the examined women during aerobics, the bal- ance sheet including the results from the track and during the aerobics classes were compared. HRmax and V̇O2 max V̇O2 max obtained during the track attempt with the average frequency of the heart’s systoles and corresponding oxygen consumption were compared (Table 5). The results suggest that the exercised Table 5. Comparison of VO2 max and HR during aerobic, with maximal aerobic test performed on a treadmill Aerobics Treadmill No. %HRmax V̇O2 max HRmax 1 22.9 65.12 50.0 209 2 35.1 65.77 45.2 198 3 50.5 68.27 44.2 194 4 20.0 63.35 39.8 205 5 12.0 58.57 39.5 199 6 22.7 67.57 46.4 187 7 23.0 59.92 49.4 199 8 48.5 67.22 47.3 215 9 29.0 60.67 48.5 187 10 27.9 60.45 43.5 197 x 29.16 63.69 45.38 199 SD 12.3 3.57 3.7 8.88 - - - - - % V̇O2 max – 93 – Wanda Pilch, Łukasz Tota, Szczepan Wiecha, Dorota Ambroży Table 6. Cost of work (kcal) during low-impact aerobic No. I part II part III part IV part Total 1 15 284 40.5 7.5 347 2 15 288 67 10 380 3 64.5 314 97.5 17.5 493 4 15 120 15 5.0 155 5 10 100 8.25 2.75 121 6 12.5 240 19 5 276 7 25 180 37.5 6.5 249 8 20 338 30 22.5 410 9 28 228 45 12.5 313 10 28.5 234 37.5 7.5 337 x 26.35 232.6 39.72 9.67 308.35 SD 19.37 79.26 26.34 6.19 113.22 work can be clasified as a light one, because it was calculated that demand for oxygen totaled on average 29.16% V̇O2 max. The average value HRmax for aerobics classes amounted to 63.7% HRmax obtained on track (Table 5). During the low-impact aerobics classes, the participants burnt off 308.4 ± 113.2 kcal on average. The span of the result was considerable and it totaled as much as 372 kcal. The highest value was 493 kcal, the lowest 121 kcal. The analysis of the cost of work at particular parts of classes points to the fact that the biggest energy expenditure was reached in part II and it equaled 232.6 kcal, whereas the lowest was reached in part IV – 9.67 kcal. In both first and second examples the individual span of results was very high: SD – 79.26 kcal and SD – 6.19 kcal (Table 6). - - - - - Discussion The change of chemical energy included in energy substrates into mechanical work carried out by a person takes place with a specific efficiency. The consumption of 1 litre of oxygen with RQ equal to 1 causes the production of energy corresponding to 5 kcal. The prolonged physical exertion executed below the anaerobic threshold is powered at the expense of changes during which most of the energy is freed from oxidation of fatty acids, glucose and amino acids. The sort of the used substrate of oxygen changes is de- pendent upon the intensity and lasting of the exertion as well as metabolic preferences of the muscle tissue. The energy used to move comes from the complicated chemical processes [11]. The high level of oxygen-related metabolic abilities is needed not only for people actively involved in athletic sport. Few people realise that the growth of maximum speed of oxygen-related metabolism of muscles enables the elderly or sick to go for a walk without much exertion and function everyday in the society. In case of the effective functioning of oxygen supply mechanism, the resynthesis of high-energy phosphogenic compounds and glycogen takes place, which later results in symptoms of tiredness [12, 13]. Physical exertion can be divided into hard, very hard, moderate and light exertion depending on energy expenditure [14]. Light exertion is characterised by energy expenditure which does not exceed 5 kcal/min, whereas hard is defined as even exceeding 10 kcal/ min [7]. Having in mind those parameters, it can be observed that exertion after 70 minutes of the low-impact aerobics exericses totaled not much than 4 kcal/min. This result is characteristic for light kinds of exertion. Nevertheless, it must be highlighted that differentation of energy expenditure of the participants fluctuated between 121 and 493 kcal, but it did not exceed the moderate kind of exertion [14]. According to Kubica [7], energy expenditure in different sports can be subdivided into groups with light, – 94 – moderate, hard and very hard character. The foundation of such division is connected with the number of kcal which are burnt off or the oxygen taken. The exertion which was reached by the examined participants of the low-impact aerobics classes corresponds to the moderate work. It can be further compared to golf classes where the average energy expenditure amounts to 300 kcal/h. Some of the participants with higher average number of the burnt kcal could compare their exertion to the race walking where the average exertion equals 550 kcal/h. Jaskólski [14] characterizes sport classes in terms of energy expenditure expressed in KJ/min in his work. The numbers gained by the participants of the study fit into the range of recreational activities 14.6–32.7 KJ/ min. These results can be compared to e.g. canoeing classes. He also presents energy expenditure in different sports depending on the body mass and the burnt kcal/min. The average body mass of the examined totalled 55 kg, and the number of the burnt kcal/ min: 4.4 kcal/min. Therefore, according to Jaskólski, the reached exertion expenditure could be compared to dancing classes (4.8 kcal/min) or, for people below the average during the classes, to recreational cycling (3.2 kcal/min). By defining the size of the workout, Christensen makes a reference not only to the number of kcal and, consequently, the value of VO2, but also to the frequency of the heart’s work. The average HR reached by the low-impact aerobics classes’ participants points to the average load of the system. Taking into consideration wide discrepancies of this parameter between the exercises, we conclude that among people with HR higher than 125 beats per minute during the research, the load was considerable [7]. Aerobics is classified as a modern gymnastic form and defined as a form of exercises carried out to the accompaniment of music. It requires from the exercising people not only good fitness but also co-ordination of movements. Taking into account the energy expenditure of a dancer during particular dances, it undoubtedly depends on the character of the dance. The similar correlation can be found during fitness classes. As it has already been mentioned, nowadays there are many types of aerobics classes. Considering their energy expenditure, it should be taken into consideration that they differ in respect of pace, character, and length of classes (what considerably varies them). In the research done by Pilch et al. [10], the energy expenditure of the low-impact aerobics classes was put to simple assessment. The results of the research highlight the fact that taking into consideration the workout, this type of aerobics is more demanding than the lowimpact one. The participants of the study burnt off 510 kcal on average with HR 148 beats per minute. There was also a substantially higher consumption of oxygen: 1.71 l/min. Judging from the aerobic effort point of view, the measurements taken during low-impact aerobics classes, conducted according to the schedule in our own research, proved beyond doubt the adequacy of terminology, since the pulse rate of examined participants reached 70% of maximal pulse level. Quite big differences in the obtained values of the parameters demonstrate personal differences in exertion ability levels, as well as co-ordination and one’s ‘attitude to exercises’. The differences in the obtained values point to the fact that there is a necessity to look generally at the number of the burnt calories during aerobics classes. This results from presented research. In the group of 10 people the differences in the obtained energy expenditure values during the same classes are so considerable that it can be claimed that the participants’ attitude and reliability have a great impact on those values. Conclusions 1. The analysis of HR and VO2 results obtained during the graded exertion test ‘until refusal’ will make it possible to estimate the energy expenditure of other exercises during which the exertion pulse is marked. 2. During the low-impact aerobics classes the participants incurred energy expenditure amounting to 308 kcal on average. 3. The obtained results make it possible to suppose that the low-impact aerobics is the exertion with the oxygen character of metabolic changes. - - - - - A simple method of assessment of energy expenditure of low-impact aerobic exercises – 95 – Wanda Pilch, Łukasz Tota, Szczepan Wiecha, Dorota Ambroży LITERATURE • PIŚMIENNICTWO [8] Pilch W: Ocena wysiłku tancerzy podczas symulacji zawodów tańca towarzyskiego w konkurencji tańców latynoamerykańskich; in II Międzynarodowa Konferencja Naukowa „Zdrowie: istota, diagnostyka i strategie zdrowotne w warunkach nauczania, pracy i sportu”, Krynica Górska, 13–15.11.2003. 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