S.S. Kozlov, candidate          
Sports and fitness complex “Olimpiysky”, Minsk, Belarus
N.V. Sizova, Ph.D.                
Maxim Tank Belarussian State Pedagogical University, Minsk, Belarus
V.V. Vasilets
E.P. Vrublevsky, Dr.Hab.
Polessky State University, Pinsk, Belarus

Keywords: step aerobics, fitness training, individually-differentiated approach, anaerobic threshold.

Introduction. One of the most popular forms of fitness training are group classes of different kinds of aerobics that unite people of different age, with various levels of physical fitness [2, 5, 13]. Theoretical and methodological literature on step aerobics contains rather contradicting recommendations about the technique of regulation of load volume and training intensity, dependance on the age, physical development and aerobic capacity of those involved is not always observed [8, 9, 15]. Nevertheless, the major requirement in conducting a fitness training is to observe the principle of individualization [6,11,14].

However, in actual practice group step aerobics classes are held without using an individual approach, with participants of different age and functional capabilities, without properly organized control of the functional state of attendants.

Thus, there is a need of a scientifically substantiated approach to the procedure of step aerobics classes in groups that unite people with different physical fitness levels. Consequently, it is relevant to develop rational techniques of organization of step aerobics exercises.  

The purpose of the research was to substabtiate the use of the individually-differentiated approach during step aerobics classes with women of different age with regard to their functional state.

Materials and methods. To achieve the objectives of the research control and experimental groups were formed consisting of women aged 23-45 years engaged in step aerobics. The experimental group (n=21) had 60-minute step aerobics classes three times a week for 6 months. The load intensity was controlled by the individual heart rate (HR) at the level of individual anaerobic threshold (IAT), followed by a change (increase) of the background music tempo and the height of the step platform (15, 20, 25 cm).

The control group (n=17) had 60-minute step aerobics classes three times a week too. The intensity of the load was the same for the whole group, and the platform remained 15 cm high throughout the research period. The degree of fatigue in this group was controlled based on subjective feelings. For self-control it was recommended not to exceed the individual pulse rate equal to 85% of the maximum value.  

The choice of the level of IAT as an indicator of individual physical working capacity is conditioned by the fact that step aerobics exercises are performed within the zone of moderate intensity. The specific feature of such a motor load is an almost complete balance between the oxygen demand and the working oxygen consumption throughout the exercise [4, 6, 10]. This is ensured by a mixed mechanism of energy supply with a dominating aerobic component, therefore, the training mode should be based on the loads at the level of individual anaerobic threshold which account for about 50% of the total volume. This is confirmed by the data from professional literature [16, 17] stating that the intensity of most of training actions intended to develop body functions and used in cyclic, primarily endurance, exercises should be within the range from the power at the IAT level to the one at the level of maximum oxygen consumption (MOC).  

The anaerobic threshold is another most important indicator of effectiveness (efficiency) of energy production, due to the fact that in case of the energy expenditure above the IAT level effective aerobic energy production that takes place mainly at the expense of fat (1 gram of fat is 33kJ) is replaced by anaerobic energy production at the expense of carbohydrates (1 gram of glucose is 17 kJ) [1, 3].

Thus, to assess the level of working capacity and functional state it is necessary to identify individual ratios of aerobic and anaerobic energy production or the individual anaerobic threshold (IAT). All the above suggests that IAT is an important individual indicator of physical working capacity, and the heart rate at the IAT level may serve as a criterion for the threshold load intensity in the fitness training process [3, 4, 11, 16].

In the experimental group of the testees the load was dosed with regard to the individual threshold HR values at the IAT level. HR control during the exercise was done using four “POLAR” cardiomonitors the cardioleaders were equipped with. Individuals with similar values of their “working” HR to the IAT level were united into subgroups (3-5 persons) with one cardioleader that was alternately used at training sessions in order to acquire objective information about the pulse of each trainee. Additionally, the cardiomonitor provided feedback allowing for comparing one’s own feelings about the state of the body with the objective values of the device, thus eliminating the element of straining the functional systems of the body caused by enhanced emotional background.  

The structure of the step aerobics class in the studied groups was as follows:

1) preparatory part – 5-7 minutes, warming-up stretching – 2-3 minutes; 2) main part – 30-40 minutes (an aerobic class aimed at formation and improvement of skills of performing basic steps, development of coordination abilities, motor memory, overall endurance, musicality and sense of rhythm); 3) final part – 1-2 minutes, cool down stretching – 4-5 minutes.

In the main part of the training session tranees learnt individual blocks (combinations) of basic steps of step aerobics 32 counts long, performed them symmetrically (with the right and the left leg as leading) and combined them into a single composition (combination). The tempo of the background music was 132-136 beats per minute at the initial stage of training and 134-138 beats per minute at the final one. In the final stage of the main part of the training session the whole composition was performed 2-3 times (a “run-through”) in order to control the progress and to assess the individual physiological (“internal”) load of the class by HR values recorded after “runs-through” performances.

The subjects of the control and experimental groups were tested before and after the six-month training cycle. The testing program was comprehensive and included sets of tests and samples to assess the level of the functional state of the body – the leading health components. The obtained results were analyzed using mathematical methods of statistics.  

Results and discussion. Changes in the processes of energy metabolism in the experimental group indicate the increasing adaptive capacity and the fitness level of the women practicing step aerobics due to individually-differentiated training modes. It is proved by the increase in the heart rate at the level of individual anaerobic threshold by 8.5% (p<0.05) and 3% (p>0.05) on average for the experimental and, control groups respectively. By the end of the training cycle a statistically significant change of morphofunctional indicators is observed in the experimental group, in contrast to the control one (Table 1).

Table 1. Changes im morphofunctional indicators of women from control and experimental groups practicing step aerobics before and after the training cycle

A number of positive changes should be noted in the women who trained in the experimental group. Concerning the fat component, the fat mass and the fat mass percentage decreased significantly (p<0.05). As for the external respiration system, the vital capacity (VC) increased by 17% (p<0.05); the percentage ratio of actual and reference VC (% RVC) - by 16 % (p<0.05); the indicator of the relative vital capacity (VC/W) - by 15% (p<0.05). A significantly lower dynamics of these indicators was recorded in the control group.

A significant decrease in the systemic and pulse blood pressure indices by 3% and 15.2% respectively was observed in the experimental group, along with a statistically significant (for 1% level of significance) decrease of the chronotropic function of the heart, resulting in a decrease in the resting heart rate index by 7.5%.

The changes that took place in the individual systems of the body caused an improvement of the overall “health level” bringing the experimental group members to a higher quality level. According to the point total in the “Health assessment” test the health of women of the experimental group “improved” to the average level and the point total increased by 30 % on average, p<0.05 (Table 2).

Table 2. “Health assessment” test indicators (G.L. Apanasenko, 1988) of women of control and experimental groups engaged in step aerobics before and after training cycle

A significantly positive trend of changes of some individual components of the “health test” was detected in the trainees of the experimental group. An increase was detected in the indices of the relative VC, the relative strength (F/M) and the HR recovery time after the Martinet test in points (by 15%, 23% and 32% respectively).

In the control group the “health test” point total increment was 7 %, and the “health level” remained the same – below average, regardless of the improvement in certain individual parameters.

Conclusions. The individually-differentiated approach to dosing of training actions with regard to the [arameters of individual anaerobic threshold (IAT) contributes to a significant improvement of the body functional capabilities ensuring the adaptation processes being developed in response to physical load.

According to the findings, step aerobics used as a fitness training along with dosing of the HR load at the level of individual anaerobic threshold promote positive changes in the body of middle-aged women. This is evidenced by the obtained significant positive changes of the functional state of the body of the trainees of the experimental group compared with the control one. 

The indices dynamics points to the growth of physical working capacity of women of this age group, the increase of their aerobic performance and physical fitness.

Thus, formation of effective functioning of the body in the framework of using individually-differentiated motor loads enhances the fitness level of women practicing step aerobics.

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Corresponding author: sok@dvs.by