Coping with physical and psycho-mental loads is a key function of dance teachers’ work. Although there is a need for research, objective data on workloads are either very limited or of earlier date.
In total, the cardiovascular loads measured for all teaching units with equal distribution were slightly below the results published by Dahlström (1997) [
3] The assumption of Dahlström (1997) [
3] that teaching children is associated with higher physical strain than teaching advanced dance students could not be proven by this study. However, the results are compatible with the findings of Wanke et al. (2015) [
4] where only 26.6% of dance teachers stated their highest physical strain teaching children aging up to 11 years and just as many (29.8%) teaching the 18–35 age group.
The cardiovascular teaching loads do not represent an adequate training stimulus for increasing basic endurance. The average intensity of a dance lesson of about 61.5% of the HRmax was in the range of a regeneration training and, thus was too low for an increase in endurance performance. Furthermore, the interval-type load design (high HR peaks and consequently high HR drops) did not correspond to the necessary long-term method (constant HR rates with low fluctuations) [
18]. This becomes particularly clear through HR drops in areas of rest frequencies and HR ups in areas of maximum performance. In addition, the high-intensity range (90–95% HRmax) is reached too sporadically and too briefly during teaching to lead to an increase in cardiovascular fitness in the sense of high-intensity interval training (HIT) [
19]. However, a good basic endurance capacity is an important aspect of prevention [
20‐
22]. Therefore, additional training should be considered.
Differences between the dance styles
It could be observed in most ballet lessons that a good division into a barre part (including supporting exercises) and a center work part (with adagio, jumps and turns) was possible. In purely quantitative terms, the barre part in this study was somewhat shorter than that stated in Schantz & Astrand’s (1984) [
17] with about 40% and in Dahlström’s (1997) [
3] study. The heterogeneous lessons in J/MD and pre-school dance could not show such a clear quantitative distinction. As to the pre-school dance, statements by Stinson (1988) [
23] can be confirmed, who determined different teaching methods depending on the mood, behavior patterns of the children and other group-specific characteristics. These factors demand flexible actions by the dance teacher and result in significant differences between the individual pre-school dance lessons.
As to the minimal cardiovascular load, no differences were found between the dance styles., Like Dahlström’s findings (1997) [
3], this study showed no differences between the dance styles for the medium and maximum loads. However, first tendencies between maximum stress in ballet and J/MD were observed. The difference between J/MD and the three other dance styles (ballet, character dance and modern dance), which Dahlström (1997) [
3] found for dancers, could also apply to dance teachers. A larger sample could possibly clarify this issue.
RPE to assess physical work loads
For the assessment of one’s own cardiovascular load in the course of a lesson significant correlations could be observed for the mean and maximum heart rate intensities to the perception of exertion, Originally intended to assess the average loads, the Borg scale seems to be better suited for assessing the maximum load regardless of the dance style. Even though all correlation coefficients were lower than stated by Chen et al. (2002) [
10] and only medium correlations could be observed, the subgroup analysis in the field of J/MD showed a correlation that was only slightly lower. Thus, these results are also somewhat lower than those of Surgenor et al. (2019) [
24], who found high construct validity for RPEs. Based on the WHO (2010) [
25] health recommendations for physical activity, which are 150 min per week of moderate intensity (corresponds to a 5 or 6 on a scale of 0–10) or alternatively 75 min per week of strenuous intensity (corresponds to a 7 or 8 on a scale of 0–10) for people between 18 and 64 years of age, the dance teachers’ teaching workload is significantly higher. In contrast, the individual average cardiovascular stress appears to be relatively low. In addition, the recorded RPE estimates of an average of 11.4 are at the lower limit of moderate stress (Norton et al., 2010). This leads to the assumption that, despite a high overall extent, no endurance-effective training stimulus is achieved through occupational activity [
26]. .Considering the high amount of lessons and regenerative breaks seemingly short [
5] as well as the realization that injury must be avoided as far as possible, a guided additional endurance training combined with a preliminary sports medical examination seems sensible in order to ensure coping with the permanent workload, prophylactic protection against injuries and faster regeneration after injuries occurring in the passive musculoskeletal system as described [
6,
7,
27,
28]. At that, the interval-like load character of many dance lessons with partly high workload peaks, which are not really striking when looking at the average values, should be taken into account. Sudden high movement intensities without a physical warm-up prior to them could pose an existential risk due to the injury hazard [
6]. An assessment of an entire work day [
28] as well as of the weeks and a monthly structure would be advantageous to better understand the loads to breaks ratio. In addition, leisure activities could be recorded in order to highlight possible compensatory hobbies or other activities involving physical exertion. The mental component of dance teachers’ profession is not to be neglected. According to the present study, teaching children is associated with lower physical stress, but DTstated a significantly higher psychological stress [
4].
The findings of Bogaert et al. (2014) [
29] showed that high physical activity does not necessarily lead to high self-perception of mental and physical health. The DTs showed a high physical activity, but according to Wanke et al. (2015) [
4] also a high feeling of load. Whether the same connections between psychosocial load, the occurrence of injuries and the duration of injuries as found in dancers [
30,
31] also applies to DTs have yet to be investigated. It is also unclear what influence the permanent support in the pre-school dance lessons and whether mostly unfavourable body position in which the dance teachers remain, affect the musculoskeletal system.
In order to obtain more valid estimates of physical exertion with the RPE scale, a longer exercise phase to familiarize with it would possibly be advantageous for subjects. In addition, in future diagnostic research, the hypothesis of dichotomy of the perception of effort on the basis of Pandolf (1981) [
32] is suggested be able to assess local and general RPE separately. Furthermore, a survey instrument for measuring mental stress would be conceivable. This would make a maximization of the correlation between heart rate and general RPE possible by partializing these RPE components because it can be assumed that the focus is mainly on the female pupils and less on the self-perception of one’s own demands.
All in all, the present study makes it clear that an assessment of cardiovascular load on the basis of heart rate recording of different teaching units of different dance styles allows only initial rough assessments. In order to obtain as precise information as possible about the cardiovascular demands, further investigations with larger numbers of test persons and perhaps other measuring methods are needed. The recording of HR could be combined with video-based and accelerometric methods, in order to discriminate physically active phases from pauses of movement.
Nevertheless, the results show that maximum cardiovascular load was achieved in some cases and that there were clear fluctuations between the individual teaching units. Significant differences between the dance styles, however, could not be observed.
As to the J/MD, the use of RPE would be conceivable in order to provide a rough estimate of cardiovascular load, especially since the effort involved in collecting data is extremely low. Furthermore, our study suggests the strong assumption that teaching in the dance classes does not usually provide an adequate stimulus in the sense of basic endurance training to increase aerobic capacity.
Balancing training in the area of basic endurance makes sense if one considers the high number and the interval-like load character of teaching units. In addition, further studies on the correlation between physical performance and acute or chronic injuries will be important in future. The evaluation of further health-related data, such as nutritional behaviour and knowledge of a healthy lifestyle, both important as basis for one’s own actions and for communicating them to the dance students, is still pending [
32,
33]. In addition, attention should be paid to explicit psychological investigations of the mental load of the occupational group of dance teachers. The analysis of lesson plans of weekly or monthly rhythms in the sense of a mesocyclic view would be advantageous in order to be able to better record the timing of teaching units and thus the rhythm between regenerative breaks and workloads.
Limitations
The main limitation of the study is certainly the measurement of the heart rate itself as a load indicator. Redding et al. (2004) [
34] and Wyon et al. (2004) [
35] emphasize that cardiovascular drifts can occur during intermittent loads accompanied by increased heart rates during pauses. Misjudgements of the load profiles would be the consequence without further participating observations. In addition, the decrease in heart rate strongly depends on the aerobic capacity of the respective test subject.
It is also to be considered that the change in heart rate depends on a number of influencing factors. Besides the purely motor activity, the hydration status [
36], music [
37] or mental load [
38] for example, have an effect on the heart rate. Since such parameters were not explicitly recorded, the heart rate as the sole parameter is at least to be interpreted with caution when assessing cardiovascular load, as already worded by Wyon (2009) [
39].
Furthermore, the authors are aware that different methods for estimating relative load intensities (% HRR, VO2R, etc.) are discussed [
40]. An attempt was made in this study to measure HRmax as accurately as possible by spiroergometry and to use it as a baseline for load relativization.
Although the average percentage of cardiovascular load did not show any major differences, the heart rate curves illustrate other stress curves that indicate the individual character of the individual dance styles and differences in the target group to be taught. A further differentiation of the lessons in B and J/MD for young people, young adults and older adults and a clear distinction between beginner and advanced lessons would be desirable for the future. However, this classification was not possible due to the few subjects who did not usually teach in all age and level groups. In general, the rather small sample only permits initial rough assessments in the sense of a pilot study and does not allow any general validity.
For the comparison between the warm-up phase and the main phase, the time division of the lessons into T1 and T2 certainly only represents a compromise consisting of qualitative and quantitative points of view, which do not always correspond to the real temporal selectivity of a teaching process and may thus lead to distortions. Measurement artifacts were caused by the application of the transmitter, the degree of moisture between transmitter and subject’s skin and the electrical contacts between transmitter belt and technical transmitter unit.