An Analysis of the Centre of Balance Trajectory in Basic Rumba Steps Outevsky David1* and Cancio Justin2
*Corresponding author: Dr. Outevsky David, Department of Dance, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada. Tel: +1.403.220.3580; Email: firstname.lastname@example.org
Dance sport is the competitive aspect of ballroom dancing. It is a very physically demanding dance form  with many practitioners around the world . It encompasses 5 genres of Latin dance: Cha Cha, Samba, Rumba, Paso Doble, and Jive. While Dance sport is a highly developed, organized and popular, there is sparse research on it in Dance Science. Technique books published by long standing organizations, such as the Imperial Society of Teachers of Dancing [3,4] and the International Dance Teacher’s Association , focus mainly on foot positions and directions. While helpful, the lack of explanation on other aspects of movement, such as timing, position in space, and rhythm, limits the potential for optimal skill development and progression.
Rumba is the slowest of the genres in Dance sport, and emphasizes the movement of the body ; its basics are often practiced in order to develop the fundamental skillset for other Latin dances. Basic movement in place and Walks are the basic techniques in Rumba, and were the movements examined in this study. A basic in place (Figure 1) consists of a rhythmical (2-3-4,1 or quick-quick-slow timing) shifting of the weight from leg to leg in a ‘feet together’ position complimented by a hip action. A Rumba forward walk (Figure 2) consists of the body (torso) moving ahead of the leg, followed by the leg quickly sliding out and arriving underneath the body to catch it aided by the hip rotation, creating a “body, foot, body, foot” movement pattern as typically described by teachers [7,8]. This study examined the centre of balance trajectory in the basic movement in place and Rumba walks, gaining preliminary insight on weight placement and movement patterns in professional and novice ballroom dancers. The findings of this study provide an improved understanding of the biomechanics in Latin dancing, and are a starting point for developing improved teaching techniques for performance enhancement and potential injury prevention for Latin ballroom dance since they uncover discrepancies between teachers use of correctional language and actual biomechanics of the technical steps required to be executed by the dancers.
Figure 1: Basic Movement in Place
Figure 2. Rumba Forward Walk
In preparation for the research, a literature review was conducted including the following areas: military gait , gait related risk factors for exercise-related lower leg pain , amputee movement , soccer shoe design , backwards gait in elderly population (balance and coordination study) , equestrian gait and injuries , left-right limb asymmetries during running  and daily gait of dancers . Some of the more relevant studies are further discussed in the following sections to help ground this investigation in existing research on gait using the Footscan equipment.
4 dancers at a post secondary dance institution were recruited for this study; 1 professional ballroom/latin dancer (participant. 1), and 3 novice dancers (participants 2, 3, and 4) with experience in contemporary and ballet were recruited for the experiment. Consent and medical forms were signed prior to engagement in the study. Two 30-minute sessions were given to the novices to learn the basic movements in place as well as forward walks in Rumba. The dance steps were then performed on the Footscan 6.2, which recorded the trajectory of their balance centres, as well as weight distribution on their feet.
Movement volume and weight distribution in feet for the basic Rumba movement in place
Participant 1 had a large movement volume, and kept the centre of balance inside the feet. Participant 2 was balanced on both sides of the feet and had no diagonal movements throughout the steps. Participant 3 was centered and had little movement volume. Participant 4 had most of the weight on the left foot and performed a majority of the steps towards the left side of the body (Figure 3).
Figure 3: Footscan balance screenshots of Rumba basic movement in place, showing weight distribution and movement volume from 4 participants.
Centre of Force travelled for the basic Rumba movement in place
Participant 1 travelled 420 mm within the first 1.5 second interval, and stayed between 300 mm to 500 mm from the starting point for the remaining 7.5 seconds. Participant 2 travelled 60 mm within the first 1.5 seconds, travelled an additional 330 mm after 3 seconds, and stayed between 390 mm to 430 mm for the remaining 6 seconds. Participant 3 travelled 270 mm in the first 1.5 second interval, and stayed between 180 mm to 270 mm off the initial starting point for the remaining 7.5 seconds. Participant 4 travelled 420 mm in the first 1.5 seconds, and stayed between 370 mm to 470 mm for the remaining 7.5 seconds (Figure 4).
Figure 4: Center of Force travelled way charts for the Rumba basic step, showing the distance the center of balance travelled in mm per 1.5 second intervals.
Area covered during basic Rumba basic step in place
Participant 1 initially travelled beyond 80cm2 during the first 1.5 second interval, and obtained a final displacement of 40cm2. Participant 2 had no initial displacement, then travelled 62cm2 after 3 seconds, and obtained a final displacement of 41cm2. Participant 3 had very minimal displacement throughout the entirety of the sequence, initially moving 6cm2 after 1.5 seconds, and having a final displacement of 1cm2. Participant 4 had an initial displacement of 36cm2, and obtained a final displacement of 19cm2 (Figure 5).
Figure 5: Area charts for Rumba basic step, showing the amount of space covered, measured in cm2 per 1.5 seconds.
Areas covered during the trajectory of the Forward Walks on the ‘push off’ leg (see figure 2)
Subjects 1, 3, and 4 covered more area on the right foot than on the left. Subject 2 tended to stay on the front of the feet. Subject 3 tended to go on the outside of big toe of the left foot. Subject 4 had much less weight area covered on the left foot than on the right (Figure 6).
Figure 6: foot scan balance screenshots of Rumba forward walk.
Pressure distribution during the Forward Walks on the ‘push off’ leg (in N per cm2)
Subject 1 had the most pressure exerted on the 1st toe (up to 7.7N/cm2) and 1st metatarsal (up to 5N/cm2) of the left leg and on the 2nd metatarsal (up to 7N/cm2) and 1st toe (up to 5.5N/cm2) on the right leg (Figure 7).
Figure 7: Pressure distribution chart for participant 1.
Subject 2 had the most pressure exerted on the 2nd metatarsal (up to 2.2N/cm2) and 4th metatarsal (up to 1.7N/cm2) on the left leg and on the 3rd metatarsal (up to 3.1N/cm2) and 2nd metatarsal (up to 1.8N/cm2) on the right leg (Figure 8).
Figure 8: Pressure distribution chart for participant 2
Subject 3 had the most pressure exerted on the 2nd metatarsal (up to 2.9N/cm2) and 1st metatarsal (up to 1.9N/cm2) on the left leg and on the 1st toe (up to 8.4N/cm2) and toes 2-5 (up to 3.5N/cm2) on the right leg (Figure 9).
Figure 9: Pressure distribution chart for participant 3.
Subject 4 had the most pressure exerted on the 1st toe (up to 1.5N/cm2) on the left leg and on the 1st toe (up to 4.5N/cm2) and 1st metatarsal (up to 2.5N/cm2) on the right leg (Figure 10).
Figure 10: Pressure distribution chart for participant 4.
Comparison of observed and metaphorical trajectories of the centre of weight through the foot during basic movement in place and forward walks Ballroom dancers are often told to create an 8-figure action, rotating their pelvis in a way that resembles the number 8, when they begin training in the Latin dances. This seems to be helpful but is a rather metaphorical expression of the actual trajectory especially considering the demand to stay ‘inside’ or toward the medial side of the foot by the technique. It can be seen from the screenshots that the actual trajectory is quite far from an ideal 8 figure and perhaps relates more to the ‘front-back-front’6 (centre of weight towards toe then heel then toe again) instruction which allows the pelvic rotation and facilitates a forward projection of the next leg. However, the weight does not travel fully weight back towards the heel but U-turns to the front midway, allowing only a minor involvement of the posterior parts of the foot in the projectile movement. Taking the difference of the two steps considered into account, the forward walks seem to have a much narrower and long trajectory due to their dynamic and mobile qualities while the basic movement in place becomes wider because of its lack of mobility therefore also defying the ‘under the body in the same place’7 descriptions to some extent.
Differences between novice and professional and compensations observed in movement The novices demonstrate various compensation patterns described below, their variety is interesting as it shows the different interpretations by dance students of the same instructions. The professional seems to be more in accordance with the described trajectory but still has right/left side deviations and seems to use more volume of the feet than the literal technique prescribes.
Some of the movement compensations which the novices used to adhere to the technical imagery included: right/left foot imbalances, going on the outside of the foot (due to pronation of the foot and/or ‘sinking in’ the hip or ankle), not going through the whole foot (e.g. only putting weight on the front of the foot during the forward walks), and limiting the movement in volume and range in order to adhere to instructions (e.g. sub. 3 during basic in place).
Implications for teaching methodology and dancer health Willems et al. found that during gait, in subjects with more medially directed centre of pressure at the forefoot flat and a more laterally directed centre of pressure at last foot contact were at greater risk of exercise related lower leg pain10. This finding potentially puts ballroom dancers at a risk of exercise related lower leg pain considering the pressure on the medial part of the foot at the forefoot flat and on the lateral part of the foot in the last foot contact during the Rumba forward walk.
Further, Praet et al.15 state that from a clinical perspective it is well known that left-right asymmetries in the human limbs may explain certain overuse injuries in sports or ergonomic situations such as running. As we have seen from the scans in this experiment, these right left asymmetries seem to be common in dancers regardless of their skill level and therefore merit further research in order to avoid overuse injuries potentially caused by neglecting them. In a study of ballet dancers, Lung and Yang found that during their regular gait the dancers are subjected to higher peak plantar pressure at the first to second metatarsal head or at the big toe, while excessive pronation angles were found at the time of push off during their regular gait. These factors in turn could be responsible for the large Hallux Valgus angles developed by dancers16. Since the trajectories of foot pressure in this experiment show similar patterns and can be seen in the scans, ballroom dancers might also be susceptible to similar patterns and the resulting repetitive strain injuries. These findings call for further research of these topics in Dance sport.
Other factors, such as the common use of high heel dance shoes in ballroom, merit further attention because they may be causing further injury to the dancers. As Coyles & Lake12 point out in their study of soccer boot studs using the Footscan: ‘localised high-pressure may lead to foot damage’ (p.9). Since wearing high heeled shoes puts pressure on the front of the dancer’s foot, combined with repetitive movements they create potential for overuse injuries in this area of the foot.
This study was limited to 4 participants, 3 of whom were novices. There was insufficient time to train participants to allow their skill level to develop beyond a beginner level. As such, the results of this study give insight into training patterns for novices but may not necessarily apply for more advanced ballroom dancers. The surface of the floor which the study was done in was uneven, which at times disturbed the movement flow of the participants. Lastly, there was a lack of literature on the use of the foot scan within the ballroom dance population, as well as within dance in general.
The foot scan can be a useful tool in the enhancement of dance teaching strategies where it can demonstrate the scientific truthfulness of such statements as ‘the weight always remains in the centre during a Rumba basic in place’ or ‘the of centre of weight travels from front to back to front during a forward Rumba walk’. It can also be used to show the compensations and interpretations that students might defer to in order to execute the taught elements. These benefits can improve the knowledge of the teachers and possibly save the student future injuries due to unseen repetitive compensations in their gait during various dance steps.
- Pytlik G. Promoting public health through dance: Dancesport as an integrated component of sport and healthy living in BC. Richmond, British Columbia, Canada: Dancesport BC. 2009.
- Bruce K. (1997), These guys are going to be monsters! Forbes Magazine. 1997.
- Imperial Society of Teachers of Dancing. (1998). Latin American Rumba. Author: London.
- Imperial Society of Teachers of Dancing. (2003). Latin American Cha Cha Cha. Author: London.
- Laird, W. (1998) Technique of Latin Dancing. International Dance Publications: Brighton, UK.
- Herbison-Evans D. History of Latin American dancing. Retrieved from University of Technology Sydney. 2010.
- Shalnev V. ISTD fellow professional (2010) The trajectory of center of balance in basic Rumba, [email] (Personal Communication, 6 Dec. 2010)
- Di Marco R. ISTD fellow professional (2010) The trajetory of the center of balance in basic rumba [email] (Personal communication, 20 Dec. 2010)
- Franklyn-Miller A., & Boyington W. (n.d.). Can the RSscan footscan D3DTM orthotic reduce lower limb injury in an initial military training setting. Retrieved from Rightside Orthotics. website:
- Willems TM, De Clercq D, Delbaere K, Vanderstraeten G, De Cock A, et al (2006). A prospective study of gait related risk factors for exercise-related lower leg pain, Gait and Posture. 2006, 23(1): 91-98.
- Van Gheluwe B, Nelen B. Plantar foot pressure of leg amputees during gait and running. 1999.
- Coyles VR, Lake MJ. Forefoot plantar pressure distribution inside the soccer boot during running. 1999.
- Xin, Y. Effect of walking backwards on the elders’ equilibrium function [Abstract]. Journal of Shandong Institute of Physical Education and Sports. 2008.
- Perino VV, CE Kawcak, Frisbie DD, RF Reiser, CW Mcllwraith. The Accuracy and Precision of an Equine In-Shoe Pressure Measurement System as a Tool for Gait Analysis. Journal of Equine Veterinary Science. 2007, 27(4): 161-166.
- Praet SFE, Wilsens J-P, Vanderhegen V, Lambrechts W, Schwellnus M Vaughan C, Noakes TD. (n.d.) Right versus Left Foot Pressure Dynamics in Running.