Throw elements in rhythmic gymnastics: muscle activation profiling tests

Dr.Hab., Professor E.N. Medvedeva1
Postgraduate student T.Yu. Davydova1
T.I. Kolesnikova2
1Lesgaft National State University of Physical Education, St. Petersburg
2Russian Rhythmic Gymnastics Federation, Moscow

Keywords: rhythmic gymnastics, group routines, apparatus throws (AT), kinematic/ balancing/ electromiographic test rates, execution difficulty rates.

Background. Modern rhythmic gymnastics routines may be described as the harmonized movement sequences reasonably standardized as required by the rules of competitions. Modern group apparatus throw actions tend to become more versatile, difficult and risky with time, with their numbers in the routines steadily increased to contribute to the technical merits and appeals of the routines [1, 3, 4, 2]. Presently the sport communities are in need of an objective test toolkit to rate the throws difficulty and quality levels (including the muscle activation patterns in the throw and catch actions) and use these data to effectively improve the technical training systems.
Objective of the study was to profile the apparatus-throw-control muscle groups activation patterns in different startup positions to provide an objective database for further progress in rhythmic gymnastics.
Methods and structure of the study. We applied for the study purposes a set of synchronized instrumental tests (including contact-free video-sequencing analysis and skin electromyography) to obtain objective movement biomechanics for the apparatus throw sequences. The core muscle group activities was profiled by the electric potentials produced by the skin electromyography, with a special focus on the key muscle groups (right/ left side trunk muscles) engaged in the throw/ catch actions as follow: musculus extensor carpi ulnaris; musculus flexor carpi ulnaris; musculus triceps/ biceps brachii; musculus deltoideus; musculus trapezius, rectus abdominal muscle; and the broadest muscle of the back. The tests gave the average amplitudes of the muscular electric activity turns, plus the integrated bioelectroactivity and reciprocity rates. The test data were processed by the STATGRAPHICS Plus mathematical statistics toolkit.
Results and discussion. The muscle activity variability analysis for the apparatus throw sequences was run in the lab fact-finding experiment. Mathematical analysis of the average amplitudes of the muscular electric activity turns (for the key apparatus-throw-control muscles) showed them varying in a wide range depending on the gymnast’s body positions. Thus the apparatus-throw-control muscle activity analysis found the musculus trapezius muscle and musculus biceps brachii being the most active – i.e. the muscles that control the head movement, abduction and arm rotation were tested with the highest electrical activity. Despite that, the greatest electrical activity (in 85.7% of the apparatus throw actions) was tested in the rectus abdominis muscle contributing to the spinal column flexion movement and trunk fixing for the active swing and accurate throw: see Figure 1.

Figure 1. Right-side trunk muscle group electric activity rates for a variety of throws, mkV (n=12)

Our analysis of the key muscle group activity for the range of apparatus throw versions found the highest number of significant differences, within the range of the standard startup positions, for the average turn amplitudes of the musculus triceps brachii and musculus biceps brachii (57.14% and 85.7%) and musculus trapezius (100%). These are the key muscles responsible for the throw accuracy. We also found the highest muscular electric activity variation ranges for the kneeled, recumbent and prone throws. This means that the starting positions and difficulty levels of the throw techniques determine success of the throw sequences.

Having compared the average amplitudes of the muscular electric activity turns (Figure 2) for the ball catches in different startup positions, we found differences in the activity and inter-muscular coordination rates. Thus the musculus biceps brachii was the most active in the one-hand standing, kneeled, sitting and 2-hand prone catch positions. The lowest activities in every key muscle was tested in the left-hand standing catch, with the rectus abdominal muscle being the least active in the right-hand standing and kneeled catch. The latter muscle was the most active in the recumbent and prone catch positions – that may be interpreted as indicative of the highest efforts of the abdominal muscle group claimed by the ball control and accurate catch actions.

Figure 2. Average amplitudes of the muscular electric activity turns for the ball catches in different positions, mkV (n=8)

Knowing that the gymnastic techniques are particularly precise in the catching sequence and require perfect inter-muscular controls, we analyzed the key muscle group activity profiles versus the startup positions. We found that, within the range of the standard bodily positions, most versatile were the meaningful differences in the average amplitudes of the muscular electric activity turns in the musculus flexor carpi ulnaris (100%), musculus biceps brachii (100%), broadest muscle of the back (87.5%) and musculus trapezius (87.5%). These muscles were activated for the shock absorption in the catch action and for failure prevention by the active flexion of the wrist and elbow joints.

A comparative analysis of muscle reciprocity rates in the ball throw/ catch sequences within the range of the starting and finishing positions made it possible to rate the inter-muscular coordination critical for the apparatus throw accuracy (Tables 1, 2). Thus the right-hand throw accuracy was secured by the high reciprocity of the left-hand muscles and other left-side muscles. It should be noted that the left-hand (non-lead hand) throws were tested with the totally different inter-muscular coordination pattern, with the throw accuracy secured mostly by the body positioning muscles than the others.

Table 1. Muscle reciprocity rates for the throw sequences in the standard startup positions, % (n=12)

 

Technical action

Trunk side

Coupled muscles

 1

 2

3

 4

1

Standing right-hand throw

Right

28,2

91,7

36,4

74,6

Left

61,1

85,5

57,8

87,1

2

Standing left-hand throw

Right

4,2

37,4

30,3

44,5

Left

19,3

93,6

59,0

16,4

3

Standing 2-hand throw

Right

24,5

82,5

21

78,2

Left

22,4

93,8

39,3

33,8

4

Kneeled  2-hand throw

Right

23,4

78,4

17

65,5

Left

97,7

38,3

55,2

87,2

5

Sitting  2-hand throw

Right

22,8

72,9

58,9

44,9

Left

46,5

33

54

72,5

6

Recumbent  2-hand throw

Right

4,9

45,1

63,1

65,2

Left

73,0

82,6

69,1

24,7

7

Prone  2-hand throw

Right

12,8

57,5

31,2

24,6

Left

84,3

30,4

48,0

17,2

Note: 1 –  rectus abdominal muscle + broadest muscle of the back; 2 –  musculus extensor carpi ulnaris + musculus flexor carpi ulnaris; 3 – musculus deltoideus + musculus trapezius; 4 –  musculus triceps brachii + musculus biceps brachii

Note: 1 –  rectus abdominal muscle + broadest muscle of the back; 2 –  musculus extensor carpi ulnaris + musculus flexor carpi ulnaris; 3 – musculus deltoideus + musculus trapezius; 4 –  musculus triceps brachii + musculus biceps brachii

In the 2-hand throws, the above patterns were the most expressed due to the body balancing and positioning efforts. The apparatus catching sequences were analyzed with a special attention to the gymnast’s ability to maintain the optimal reciprocity in the shock absorption efforts: see Table 2. We found that the optimal shock absorption with the low reciprocity of muscles was secured by unlimited hand(s) movement amplitude. The high amplitudes of the arm elements, however, were interpreted as indicative of high difficulty and special movement control skills required by the action. 

Table 2. Reciprocity of ball-catch-control muscles in the standard startup positions, % (n=12)

 

Technical action

Trunk side

Coupled muscles

 1

 2

3

 4

1

Standing right-hand catch

Right

32,5

44,7

37,6

97,3

Left

37,7

40,8

54,9

90,7

2

Standing left-hand catch

Right

92,1

43,1

18,1

55,7

Left

16,9

38,9

83,1

45,6

3

Standing 2-hand catch

Right

81,4

55,3

56,3

96,9

Left

20,6

57,5

49,5

33,4

4

Kneeled  2-hand catch

Right

26,4

68,4

23,5

68,6

Left

93,8

51,9

44,7

70,8

5

Sitting  2-hand catch

Right

54,9

63

22

30

Left

71,4

67

83,7

98,6

6

Recumbent  2-hand catch

Right

4,7

92,2

57,4

95,3

Left

27,2

32,6

43,6

65,9

7

Prone  2-hand catch

Right

9,9

80,7

35,7

23

Left

60,5

39,2

96,9

7,5

Note: 1 –  rectus abdominal muscle + broadest muscle of the back; 2 –  musculus extensor carpi ulnaris + musculus flexor carpi ulnaris; 3 – musculus deltoideus + musculus trapezius; 4 –  musculus triceps brachii + musculus biceps brachii

Note: 1 –  rectus abdominal muscle + broadest muscle of the back; 2 –  musculus extensor carpi ulnaris + musculus flexor carpi ulnaris; 3 – musculus deltoideus + musculus trapezius; 4 –  musculus triceps brachii + musculus biceps brachii

The highest reciprocity and, hence, the lowest shock absorption rates were found in the sitting 2-hand catch sequence (75% of the coupled muscles). The highest symmetry in the right/ left side trunk muscles activity was found for the carpi ulnaris responsible for the ball grip and hold in the standing and sitting positions. The only exclusion were the recumbent and prone 2-hand catch sequences that give no chance for assistant leg/ trunk movements, with the whole burden of the move taken by hands. These apparatus throw sequences were tested with the dominant reciprocity of the musculus deltoideus + musculus trapezius couple (63.3% of the range) indicative of the ball catching by a straight-elbow arm. Only the prone 2-hand catch above the head was tested to include a soft absorption by the bent arms.
Conclusion. The study found the muscular electrical activity and inter-muscular coordination (reciprocity) being largely determined by the apparatus throw action startup position. The apparatus throw sequence difficulty class was found particularly high in the startup positions making impossible the key phase of the movement sequence – that is the high-amplitude swing of the apparatus; and this is the key reason for the high muscular electric activity and trunk muscles reciprocity in such positions. The apparatus catching sequence was found particularly difficult when the bodily position gives no chance for the fast shock absorption without detriment for the movement smoothness. On the whole, the apparatus throw sequence difficulty class will be determined by the throw and catch difficulty levels. This finding is recommended to be taken into account in the apparatus throw difficulty classifications and in trainings of these elements in the group gymnastics routines.

References

  1. Kryuchek E.S., Terekhina R.N., Medvedeva E.N. et al. Modelnye kharakteristiki komponentov ispolnitelskogo masterstva gimnastok gruppovykh uprazhneniy, vystupayuschhikh v sorevnovaniyakh po mnogoboryu [Model characteristics of performance skills of female gymnasts in group exercises performing in all-around competitions]. Uchenye zapiski universiteta im. P.F. Lesgafta. 2015. no. 2 (120). pp. 76-80.
  2. Nesterova T.V., Kozhanova O.S. Faktor sovmestimosti pri komplektovanii komand v gruppovykh uprazhneniyakh khudozhestvennoy gimnastiki [Compatibility factor when making teams in rhythmic gymnastics group exercises]. Fizicheskoe vospitanie studentov. 2009. no. 1. pp. 32-34.
  3. Terekhina R.N., Medvedeva E.N., Suprun A.A. et al. Obosnovanie podkhoda k opredeleniyu slozhnosti elementov khudozhestvennoy gimnastiki i ikh tekhnicheskoy tsennosti [Justification of approach to determining complexity of elements in rhythmic gymnastics and their technical value]. Uchenye zapiski universiteta im. P.F. Lesgafta, 2015, 3 (121), pp. 146-149.

Corresponding author: elena.vlgafk@rambler.ru

Abstract
Modern rhythmic gymnastics routines may be described as the harmonized movement sequences reasonably standardized as required by the rules of competitions. Presently the sport communities are in need of objective test tools to rate the throws difficulty and quality levels (including the muscle activation patterns in the throw and catching skills) and use these data to effectively improve the technical training systems. Objective of the study was to profile the muscle activation patterns of throw movements in different starting positions to provide an objective database for further progress in rhythmic gymnastics. We applied for the study purposes a set of synchronized instrumental tests (including the contact-free video-sequencing analysis and skin electromyography) to obtain objective movement biomechanics for the apparatus throw sequences. The core muscle group activity was profiled by the electric potentials produced by the skin electromyography, with a special focus on the muscle groups including right/ left side trunk muscles engaged in the throw/ catching movements: musculus extensor carpi ulnaris; musculus flexor carpi ulnaris; musculus triceps/ biceps brachii; musculus deltoideus; musculus trapezius, rectus abdominal muscle; and the broadest muscle of the back. The tests produced average amplitudes of the electric activity turns, integrated bioactivity and muscle reciprocity rates; and the test data were processed by the STATGRAPHICS Plus toolkit for analysis.