Technique Magazine - March 1988

THE OFFICIAL TECHNI

March 1988

PAID Permit No. 7867

Indianapolis, Ind.

PUBLICATION OF THE UNITED STATES GYMNASTICS FEDERATION

Vol. 8, No.1

March 1988

Vol. 8, No.1

Inside This Issue 4-6

McDonald's American Cup Men's Technical Report

8-9

Somersault Trajectory Differences: Foam Block Versus Coil Spring Floor

10-12 Implementation Of A Profiling Prediction Test Battery In The Screening Of Elite Gymnasts

By Robert Cowan Men's Program Administrator

By W.A. Sands University of Utah G.S. George Ph.D. University of SW Louisiana St.

By Mark D. Grabiner, Ph.D. University of Southern California Robert McKelvain, Ph.D. Harding University

USGF Calendar Of Events Safety Certification Schedule Rhythmic Gymnastics From F.I.G. Update D.J. Milem 17 Survey To Help Loss Of Athletes Age Group Chair., Region VIII 18-20 An Insight Into The

By Hardy Fink Biomechanics Of Twisting University of British Columbia

14 15 16

Cover photo © 1988 USGF, by Dave Black CHANGE OF ADDRESS AND SUBSCRIPTION INQUIRIES: In order to ensure uninterrupted delivery of TECHNIQUE magazine. notice of change of address should be made six to eight weeks in advance. For fastest service. please enclose your present mailing label. Direct all subscription mail to TECHNIQUE SUBSCRtPTIONS. Pan American Plaza. 201 S. Capitol Ave .. Suite 300. Indianapolis. IN 46225. POSTMASTER: Send address change to TECHNIQUE. Pan American Plaza. 201 S. Capitol Ave .. Suite 300. Indianapolis. IN 46225.

TECHNIQUE is published quarterly for $12.00 by the United States Gymnastics Federation. Pan American Plaza.

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IN . Subscription price: $12.00 per year in United States; all other countries $24.00 per year. Back issue single capies $2.00 plus $1 .00 postage/handling. All reasonable care will be taken. but no responsibility can be assumed for unsolicited material; enclose return postage. © 1987 by USGF and Technique. All rights reserved. Printed in USA.

Publisher Mike Jacld Education/Safety Editor Dr. Gerald George Production Michael G. Botkin UNITED STATES GYMNASTICS FEDERATION BOARD OF DIRECTORS: Executive Director: Mike Jacki. Athlete Representatives: Lydia Bree; Peter Vidmar; Linda Kardos; Tom Beach; Kathy Johnson; Tim Daggett; Kelly Garrison. Amateur Athletic Union: Jerry Hardy. American Sokol Organization: Norma Zabka . American Turners: Harry Warnken. Members at Large: Linda Chencinski. NCAA Gymnastics CoachesMen: Fred Roethlisberger, University of Minnesota . NCAA Gymnastics Coaches-Women: Judi Avener, Penn State University. National Association for Girls and Women In Sports: Dr. Mimi Murray, Sprin~field College . National Association of Women s Gymnastics Judges: Dale Brown.

NCAA: Sylvia Moore, Oregon State University; Gail Davis, Rhode Island College; Jerry Miles, do NCAA; Wayne Young, Brigham Young University. NAIA: Bonnie Morrow . NHSGCA: John Brinkworth. National Federation of State High School Athletic Assoc. : Sharon Wilch ; Susan True .

National Jewish Welfare Board: Courtney Shanken . NJCAA: Dave Rowlands, Tru man College.

"NGJA: Mike Milidonis. USAIGC: Ed Knepper.

Men's Elite Coaches Assoc.: Jim Howard, University of Nebraska. USECA for Women: Roe Kreutzer; Steve Whitlock. Youn~ Men's Christian Assoc.: Cliff Lothery. Jr. Boy s Gym. Coaches Assoc.: Rich Boccia. President: Mike Donahue.

EXECUTIVE COMMITTEE : President: Mike Donahue. Secretary: Judi Avener. Vice President: Jim Howard. Executive Director: Mike Jacki. FIG Technical Committee: Jackie Fie. FIG Rhythmic Technical Comm.: Andrea Schmid. FIG Men's Technical Committee: Bill Roetzheim. Vice President for Women : Sue Ammerman. President Emeritus: Bud Wilkinson. Athlete Representatives: Kathy Johnson; Peter Vidmar; Larry Gerald.

Members at Large: Mike Milidonis; Linda Chencinski.

Associate Contrnt Editors SPORTS MEDICINE COMMITTH

Merrill A. Ritter, M.D.

FIG BULLETIN If you would like to subscribe to the FIG BULLETIN, please indicate your interest in writing by JANUARY 31, 1988. Due to the fluctuating currency exchange, the subscription price has not been determined. Last years price was $25.00. Send requests to: John Hewett, 201 S. Capitol Ave., Suite 300, Indianapolis, IN 46225.

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SAFETY COMMITTEE Dr. Marc Rabinoff EDUCATION COMMllTEE Dr. Carland O'Quinn BIOMECHANICS COMMITTEE Dr. Marlene Adrian, Director SPORTS PSYCHOLOGY COMMITTEE Dr. Keith Henschen, Ph.D. EXERCISE PHYSIOLOGY COMMITTEE Dr. Pat Eisenman. Ph.D.

Unless expressly identified to the contrary. all articles, statements and views printed herein are 3uributed soley to the author and the United States Gymnastics Federation expresses no opinion there on and ass umes no responsibility

thereof.

Technique

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American Cup Men's Technical Report

By Robert Cowan USGF Men's Program Administrator he 13th American Cup proved to be "lucky 13" for Kevin Davis as he led all the American males on the day of finals . However, on Saturday in the preliminaries, the day belonged to Dan Hayden who finished 1st.

The 1988 American Cup in Fairfax, VA was in many ways, one of the more exciting competitions in recent years. While the competitive field was quite narrow relative to athletes who actually were capable of winning, the level of performance was extremely high. In other words, very few athletes could put 6 GREAT routines together, but all of the athletes were world class on at least three or four events .

Saturday' s competition came down to those people who did not fall off or fall down moving into Sunday .

Charles Lakes-USA, Scott JohnsonUSA, Li Ning-CHN, Mike InglisCAN, Liubomir Geuraskov-BUL, Laszlo Boda-HUN, Alejandro PinecheMEX, and Jeong Sik Lee-KOR; ALL fell on at least one event and some fell two and three times. Dan Hayden won the event on Saturday with 58.05, with Kevin Davis in 4th with 57.70, Scott Johnson was 6th with 57.50 and Charles Lakes was 14th with 55 .85.

However, due to the two man rule advancing, Scott was not in the Sunday event.

Dan Hayden certainly has the international experience and visibility to win the American Cup, IF he is consistent . Kevin Davis has the gymnastics skills and execution, but exposure at this level would have kept him from winning, or made it very difficult.

Eight athletes advanced to the finals on Sunday which is of course a totally new meet. It is all around again, and scores do not carry.

The event on Sunday for all intents and purposes proved my theory. Dan touched down on FX, did a 9.4 vault which scored 9.4 and finished 4th .

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Kevin Davis was rock solid during both the McDonald's American Cup and International Mixed Pairs taking third and first respectively. Davis scored a 9.90 on pommel horse during the Mixed Pairs to lead his team to victory. (All photos Š 1988 USGF, by Dave Black).

Kevin Davis was rock solid, besting his Saturday total to 58 .15 and finished 3rd. Other than wishing Dan had a 9.6 vault and had not made the error on FX, you could not have asked for more out of either gymnast.

Finalists included Marius TobaROM, Igor Korobchinsky-USSR, Sven Tippelt-GDR, Antonio Trecate-ITA, Casimiro Suarez-CUB , Takahiro Yamada-JPN and of course, Hayden and Davis .

Toba was very impressive en route to the 58.45 total which edged the Soviet by .25 and earned him the first Romanian title of American Cup Champion . In fact, it was exactly 13 years before when a Romanian (Nadia Comaneci) and an American (Bart

Conner) shared American Cup Champion honors. This year it was Toba and Phoebe Mills-USA .

A listing of the routines for the top eight gymnasts follows this report.

MIXED PAIRS The Mixed Pairs were held in Allentown and hosted by the Parkettes/Gymnastrum. 19 pairs started in the first round with Kevin Davis paired with Phoebe Mills, Dan Hayden with Chelle Stack, Scott Johnson with Brandy Johnson and Charles Lakes with Hope Spivey . There were also some Parkette girls paired with Gymnastrum and International Gymnastics school boys to give some local interest to the event.

Technique

Dan Hayden's early routines were hindered by a stiff neck but he recovered to perfectly execute his half-in, half-out over the bar dismount on high bar.

Only two American pairs can advance and Charles Lakes and Hope Spivey got underscored on their first event (HB and V), and thus were eliminated. Only Kevin and Phoebe advanced to the final round which witnessed the Romanian pair, the Soviet pair and the USA pair battle for the Mixed Pairs title. Actually Kevin and Phoebe came in to the final round with 0.075 lead, but this was soon eliminated by first the Romanian pair who got 9.6 on FX and 9.7 on BM. Next came the Soviet pair and Baitova went 9.9 on FX (although underrotating a 3/1 dismount) and Korobchinsky went 9.9 on PB with a routine which had at least 0.2 in execution decluctions .

For my money, the meet was over and it appeared the " fix " was in for the Soviets. However, nobody told Phoebe and Kevin. Phoebe did a great FX set, even though she dismounted 2/1 instead of double back and scored 9.9. Kevin did an excellent PH set with 4 D' s and flawless execution and scored 9.9!! The USA won.

AMERICAN CUP FINALIST ROUTINES Floor Exercise Antonio Trecate-Italy-Double layout-straddled arabian 1 %-flairs to handstand-wide arm press-tuck double dismount Takahiro Yamada-Japan-Tucked full in-1 1h to punch front-front fronttucked double dismount Marius Toba-Romania-Piked full indouble back punch front step out, round off, flip flop , 111 punch front-Ill side-2/1 punch front dismount Igor Korobchinsky-USSR-Double layout, flip flop tucked back-Arabian 1 %-Wide arm press-tucked double dismount Kevin Davis-USA-Tucked full in-2/1-break dance sequence-side sorni-tucked double dismount Casimiro Suarez-Cuba-Double layout-tucked III in-Layout punch

Phoebe Mills teamed with Kevin Davis to win the International Mixed Pairs competition.

Mills, originally not scheduled to compete in these events, seized the opportunity to win them both .

Technique

front 11f4 -tucked double dismount Dan Hayden-USA-Arabian double front, headspring out-Front through to Double back-wide arm press-layout back-tucked double back dismount Sven Tippelt-GDR-Layout/pike double-Arabian 1 %-layout back punch front-flairing spindle-wide arm presstucked double back dismount Pommel Horse Toba-Back kip cross-pullout-yamawaki-yamawaki-whippet-handstandback giant-cross-straightl straight press (straddled)-double layout Vault Davis-Cuervo Suarez-1 arm straddle layout tsuk III

Hayden-Handspring front piked Tippelt-Piked Cuervo Yamada-Piked Cuervo Toba-Layout tsuk III Korobchinsky-Layout tsuk III Trecate-Cartwheel pike front Parallel Bars Hayden-Peach Ih -giant Ih -giantfront rise-back pirouette-" V" -Press straight straight-Stutz hand-back toss hand-back toss hand stutz handtucked double 5

Tippelt-Peach hand-giant-giant % to end-giant glide reverse cut-swing hand-healey-front pirouette-stutzgiant glide to end-double front dismount Yamada-Peach hand-pirouette forward-stutz % turn to one rail-glide from side _" V" -press-1f4 turn indiamidov-front rise-swing hand-stutztucked double dismount Toba-Glide on end- flairs-straddle planche-giant cast-healey-swing handstand-healey-front 11f4 cutback swing handstand-stutz-tucked double dismount Korobchinsky-Cast support-back pirouette-giant-stutz-healey downback stutz-hop pirouette-stutzdiamidov-tucked double dismount Trecate-Glide-reverse cut-peachreverse cut-handstand-reverse pirouette-diamidov-diamidov with % turnside glide up to straddle-press handstand- % turn in-stutz-"V"double front Davis-From side-glide-straddle "L"press-pirouette into diamidov-healeyhealey-% pirouette down to back stutz-front roll-cuts to ilL" -presstucked double Suarez-Peach hand-stutz-giengerfron t rise-" L' ,-press-diamidov-back

toss-back toss-stutz-tucked double dismount Horizontal Bar Yamada-Stemme-stalder-inside stalder-pirouette-tkachev with legs together-jam eagle, eagle, pirouettedouble layout Toba-Back rise hand-stalder-blindendo-pirouette-tkachev-higgins to eagles-double double Korobchinsky-Back rise hand-Ill

gienger-kip change-higgins to invertsyeager-triple back Trecate-Stemme pirouette to 1 arm-I arm tkachev-catch with 1 arm-healeyjam eagles-pirouette-double layout Davis-Stemme stalder-1 arm healey1 arm giant-1 arm tkachev-jam eagleinverts-pirouette-double layout Suarez-Stemme pirouette- 1% gienger- III spin to 1 arm- giengerhiggins-eagle- layout III in Hayden-Back rise hand-stalderblind-eagles-kovacs-endo-pirouettefull twisting kovacs Tippelt-Mixed grip stemme-pirouette-1 arm tkachev-tkachev-blind change-1 arm giant-pirouette-jameagle-inverts-barani in OTHER UNUSUAL SKILLS Laszlo Boda-Hungary-FX-Excellent 3/1-double back punch front to round off flip flop 1% twister to punch barani Also did handspring, front flip flop, front flip flop to 1 % dive roll. Li NingChina-Did piked double double at least 1 mile high .

Boda-Hungary-SR-did Guczoghy into immediate triple flyaway Penichi-Mexico-Vault-did III twisting cuervo

Igor Korobchinsky's parallel bars routine was one of his best .

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THE OFFICIAL TECHNICAL PUBLICATION OF THE UNITED STATES GYMNASTICS FEDERATI ON

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7

Somersault Trajectory Differences: Foam Bloc Versus Coil Spring Floor W.A. Sands, Ph.D. Assistant Women's Program Administrator Human Performance Research Laboratory University of Utah G.S. George, Ph.D. Biomechanics Consultant Women's National Program University of South Western Louisiana oncern was voiced by coaches of the 1987 World Championships team that our national team gymnasts had a great deal of trouble staying within the floor exercise boundaries during performance.

The deductions for going out of the boundaries can be a considerable drain on the team and individual scores. The floor exercise surface varies in different competitions, but the boundary dimensions remain the same .

Moreover, since a tumbling pass consists of multiple alternating floor contacts and flight phases, the study of the length of trajectories on different floor surfaces seemed warranted. The nature of the flight phase of a somersault or other airborne skill can be defined closely by knowing the quantities of the horizontal and vertical components of velocity at the moment of departure from the floor surface (Hay, 1973) . These quantities are partially or completely determined by the strength of the athlete, velocity of the body at contact with the floor, specific take off actions, and the qualities of the floor surface .

The variables of strength and technique require rather indepth analysis using sophisticated instrumentation and preclude generalizable conclusions for the majority of national team members . The large amount of time invested in such investigations make them largely impractical for team wide generalizations. Varying floor area conditions in elasticity and loading qualities could be a major contributing factor to jumping ability. Stride length

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and other running mechanics have been shown to be affected by running surface (McMahon, 1985; MacMahon & Greene, 1978; McMahon & Green, 1979). Floor exercise areas involving conical and cylindrical springs have been compared showing differing characteristics and resulting in differing muscular innervation patterns (Gormley, 1982) .

The purpose of this investigation was to determine if trajectory lengths of a layout somersault were different when performed on a coil spring floor exercise surface or a foam block floor exercise surface. The design and construction of these two types of floor exercise surfaces are quite common in the United States and abroad. Athletes may train on one particular style of floor and then compete on the opposite style . If floors have different performance characteristics, it is imp ortant that coaches and athletes know what these variable charactertistics are. Moreover, these characteristics should be identified so that the expected performance could be more accurately predicted.

METHODS Uring the Senior National Training Camp in Altamonte Springs, Florida the gymnasts (N = 26) of the senior national team were divided into three groups for physiological and biomechanical testing . As the three groups rotated to each testing station they received a series of physical performance tests .

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One of these stations was the layout somersault trajectory distance test.

Two groups of gymnasts began on the foam floor surface, and one group began on the coil spring surface. Each group was asked to perform a run to round off, flip flop, and layout somersault as they would perform their first major floor exercise tumbling pass .

Each gymnast performed three trials on each floor surface. Two skilled coaches present at the camp visually noted the take off and landing indentations in the matting surface and immediately measured the length of the trajectory with a metric tape measure.

The trials data were subjected to reliability analysis using Cronbach's Alpha model to determine if there were any trends across the trials. Following this determination the average of the trials was used for the final data value (Henry, 1967). These values were then assessed by a matched pairs ! test, and a Pearson product moment correlation coefficient (!).

RESULTS eliability analysis using Cronbach's Alpha model showed that there were no significant differences between the trials on either the coil floor (f(25,2) = 0.67, p>.05) or the foam floor (f(25,2 = .020, ÂŁ>.05).

The Alpha values for reliability were .85 for the coil floor and .89 for the foam floor. Both of these values indicated that the reliability of the trials was quite high . Following this analysis the data were reduced by calculating the mean of the three trials as the data for analysis.

Table I shows the descriptive statistics for the population of senior national team members.

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Technique

Table I Descriptive Statistics Item

Mean

152.47 Height (cm) Weight (kg) 45.15 Foam Trajectory Distance (cm) 175.18 Coil Trajectory Distance (cm) 168.58

Std Deviation

6.95 5.94 23.71 20.47

The results of the matched pairs! test showed that there was a difference between the floor types (!(25) = 2.20, ÂŁ<.05) . The Pearson product moment correlation coefficient reached!: = .77 (ÂŁ<.05). The correlation coefficient indicated that approximately 59% of the variability in one trajectory length on one floor surface type could be predicted by knowing the other trajectory length .

DISCUSSION he difference between the mean values of trajectory lengths indicates approximately a 4.15% increase in distance on the foam block type of floor. This translates to only a 6.6 cm increase (approximately 2.6 inches). This distance would appear to be hardly worth worrying about.

However, one must consider that there are several other trajectories in the entire tumbling pass. If the 4.15% increase in distance of the somersault can be translated to the entire pass this could become a very significant figure .

The length of the diagonal of the floor exercise area is 16.97 m . Taking 4.15% of this distance returns 0.70 m . (approximately 27.6 inches) or slightly more than two feet.

The 0.70 m distance probably

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represents an inflated value due to the differences in the goals of each of the trajectories of a tumbling pass. For example, running steps, snap downs, flip flops, etc. are of lower height. Our best approximation of the increase in length for the total tumbling pass is 30.5-45 .75 cm (12-18 inches). We offer for consideration that the corner boundaries be modified for those athletes who train normally on a coil spring floor and are going to compete on a foam block floor. Figure 1 shows a possible modification scheme.

In conclusion, it appears that the nature of the construction of the floor exercise surface may have an impact on the length of a somersault trajectory.

Moreover, the length of the entire tumbling pass may be affected by the same phenomenon. This effect may be further exaggerated by placement of the floor exercise surface on the competition podium. A theoretical cause of the differences in trajectory lengths may lie in the restitution characteristics of the tumbling surfaces.

RECOMMENDATIONS/COACHES TRANSLATION: softer and therefore slower floor means that performers will be in contact with the tumbling surface for a longer duration of time . This means that their rebound angles for virtually any airborne skill will be greater than on harder/springier surfaces. A greater rebound angle will cause the performer to travel further relative to a stiffer surface. The net result is that the potential for landing out of bounds is increased. To compensate for this potential tendency it is recommended

A

Figure 1 -

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Modified Boundary

(rupe)

Technique

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Floor Exer.

Area

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\. 15-23.5cm.

6-121nclles

Standard Boundary' I I --'

that the corner boundaries be moved in 15-23.5 cm (6-12 inches) on coil spring floors during the routine preparation preceding competition on a foam block floor.

OBSERVATION Visual observation and comments made by Europeans-their arm lift is similar to ours for back rotation, BUT, they drop their arms behind them with a neurtral head position giving a quicker rotation and more control during the skill and in the landing. Best advice, slow down the film of the recent meets and study the position of ' the set-up for double backs and double layouts. It becomes more obvious.

It looks awkward, but appears to be effective.

During the training sessions that the vaulting board was used to a great deal during training for certain drills.

1. Handstand pushups with the coach "sculpturing" the body at the top and the bottom.

2. Back tucks off board with emphasis on sticking-also pikes-back 1/2 3. Handstand snapdown from board-hs snap down back-back pikeback layout-back with 1/2 etc .

4. Athletes squatting on board with the coach sitting on their back/shoulders and bouncing the board slowly .

When questioned-reply was it strengthens and stretches the achilles.

REFERENCES

J. T. (1982). An investigation of two spring floor type characteristics and the muscular response in gymnasts of different body mass and skill performance levels. Underdale: South Aus-

Gormley,

tralia . South Australia College of Advanced Education. Author.

Hay, J. G . (1973) . The Biomechanics of Sports Techniques. Englewood Cliffs, NJ: Prentice Hall.

Henry, F.M . (1967) . " Best" versus "average" individual scores.

Research Quarterly, 38, 317-320.

McMahon, T.A. (1985). The role of compliance in mammalian running gaits . Journal of Experimental Biology, 115, 263-285 .

McMahon, T.A ., & Greene, P .R. (1978) . Fast running tracks. Scientific American, 239, 148-163.

McMahon, T.A. & Greene, P .R. (1979) . The influence of track compliance on running. Journal of Biomechanics, 12, 893-904 .

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Implementation Of A Profiling Prediction Test Battery In The Screening Of Elite Gymnasts By Mark D. Grabiner, Ph.D. University of Southern California and Robert McKelvain, Ph.D. Harding University This research has been supported, in part, by travel grants from the United States Gymnastic Federation. This project is part of the United States Gymnastic Federation Men's Junior Olympic Sport Sciences Program.

Introduction he international success of the sports sciences programs of the Soviet Union and Soviet-block countries has been related by some as being most directly to the selection of the most able and talented young individuals and the creation of an environment that makes possible the attainment of athletic mastery (Schneidman, 1978) .

One may assume that the status of training environments worldwide is the less disparate of the two. The solution to the questions regarding the selection of those young athletes that are predisposed to successful athletic participation in high-level competition has represented an elusive quarry to sports scientists for nearly a century .

Any number of physiological, biomechanical, or anthropometric models of elite athletes have been reported, however, the implementation of such data remains, for the most part, limited . That is, they have not been administered on what may be considered a large scale. Grabiner and Dillman (1982) proposed a method by which athletes could be profiled based upon performance in 14 standardized fitness tasks and morphological data .

It was assumed that performance on the tasks, which were selected to yield information regarding a metabolic

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energy source continuum, would correlate well with the athletes' bodytype and therefore allow objective counseling with respect to a specific group or type of activities. A modification of the original test battery, which was reduced to seven timed performance tasks and whose calculated output variable represented average power output per unit body weight, was reported by Grabiner and Dillman (1984).

The average power output was standardized (Z-scores) so as to partial out the effects of individual body weight and height. Each of seven tasks, chosen to represent most of the body's major joint actions were performed by a group of 40 college-aged males (Mean: age = 22.1 years, height = 179 cm, weight = 75.3 kg) for 60 seconds.

The tests that were administered were pushups, situps, pullups, dips, vertical jumps (12 inches), handstand pushups, and squat thrusts. The number of correctly performed repetitions during the 60 seconds were recorded and used as input to a computer program which, based upon the athletes sex, height, and weight, calculated the vertical displacement of the overall body center of mass during each repetition, the work performed against gravity during each repetition, and ultimately the average power output during the performance period per unit of body weight (W/N).

It was discovered that athletes of various activities displayed specific profiles that qualitatively differentiated between groups and were consistent within groups. Represented in Figure 1 are the standardized scores of wrestlers (N = 3), an elite college baseball pitcher (currently professional), and a female intercollegiate middledistance swimmer (scores representing deviations from a female test population. More notable than differences in any particular score, is the Civerall profile, or shape, generated by the continuum of scores .

Methods he possible role that such a testing/ screening procedure could serve attracted the attention of the USGF Mens' Jr. Elite Program and two separate groups of young athletes were tested with a modified battery at the USOC Training Center in Colorado Springs . The modification of the battery included stiff-stiffs (on the parallel bars) in lieu of squat thrusts.

The first group was tested during the 1985 Spring Training Camp (N = 15, Mean: age = 16.5 years, weight = 50.7 kg, height = 164.33 cm) . The tests for this group were administered in "random" (athletes' preferred) order.

Athletes were allowed essentially as much rest between tests as they desired.

With the exception of the stiff-stiffs, the test battery was also administered to a control group of athletes (nongymnasts) all older than 12 years old (N = 62, Mean: height = 169.92 cm, weight = 62.7 kg) . The results from this group were implemented as baseline values against which the gymnasts scores could be plotted so as to generate the gymnast profile.

The testing of the second group of USGF athletes during the 1985 Summer Training camp (N = 27, Mean: age = 14.76 years, weight = 51.39 kg, height = 158.47 cm) was conductedm such a way so as to control for the two factors which were free to vary in the first group. These two factors were the order of test administration and the amount of rest allowed between tests.

The test order was pullups, pushups, situps, dips, vertical jump, handstand pushups, and stiff-stiffs. Each athlete had eleven minutes of recovery between tests.

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By selecting the best athletes, the United States could push themselves to the top of the gymnastics world like they did during the recent Pan American Games. (USGF photo Š 1987, by Dave Black).

Technique

Results esults of the first data set illustrate that the gymnasts are more homogeneous than the control group with respect to the performance tasks. The average coefficient of variation for the six tests was 31 .28 percent versus the 59.0 percent for the control group. Additionally, and perhaps more importantly, the means of the gymnasts' scores were found to be an average 2.05 standard deviations above the control group's mean values.

Results of the second group of USGF athletes tested illustrated two notable points. Firstly were the similarities in scores and profiles from one group to the other (!: = .92).

Again, the mean of the normalized scores was 2 .04 standard deviations above those of the control group . Secondly, the possible effects of controlling for the order of test administration and amount of rest was observed. The coefficient of variability, 31.28 percent in the first group of athletes was reduced to 24.71 percent (Table 1) .

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Technique

Table 1 Descriptive statistics for the gymnastics and control groups.

USGF Group #1 Test

Mean (W/kg) SD

CV

pullups 97.56 31.34 situps 201.04 28.55 pushups 191 .21 75 .33 handstand 38.82 11.77 pushups dips 186.70 66.40 vertical jump 14.64 4.80 stiff-stiffs 61.66 22.40 USGF Group #271

32 14 39

pullups 93.57 situps 197.47 pushups 292.54 handstand pushups 27.29 dips 163.41 vertical jump 17.68 stiff-stiffs 30.48 Control group

15.67 19.27 45.76

17 10 16

8.97 41 .12 4.39 14.40

33 25 25 47

pullups 37.74 situps 119.92 pushups 150.79 handstand pushups 10.97 dips 52.14 vertical jumps 14.47

24.60 24.10 68.51

65 20 45

10.83 40 .27 6.92

99 77 48

30 35 33 36

The predictive capabilities of the test battery with respect to performance was investigated using multiple regression. Overall national ranking of the second group of athletes, ranging from 12 to 64, was used as the dependent variable and the power output scores were used as independent variables. The equation, using standardized regression coefficients, Overall rank = - 28.96 + .222 * X, - .009 * X2 + .705 * X3 - .626 * X4 - .204 * Xs - .009 * X6 + .065 * X7 where, Xl = pullup power output X2 = situp power output X3 = pushup power output X4 = handstand pushup power output Xs = dip power output X6 = vertical jump power output X7 = stiff-stiff power output, accounted for 44.02 percent of the variance associated with overall rank (R = .6635).

Conclusions he gymnast profile is markedly different than any other profile previously encountered (Grabiner and Dillman, 1984) . It

T

11

seems conservatively reasonable to suggest that junior elite gymnasts demonstrate levels of average power output that distinguish them from average/normal athletes of similar age range. Despite the relative insensitivity of inherent in the measurement of average power output values, knowledge of these parameters seems to allow some discrimination of gymnastic ability without so much as any gymnastics measures. It remains to be seen, however, as to the predictive value of the test battery with respect to an "unknown" population. That is,

having only the power output scores, whether the model will allow for prediction of overall placement of gymnasts. Of significant value is whether, given scores of young, gymnastically- untrained individuals the model can suggest gymnastics potential. This, then, could be the sounding board for a program whose focus is the selection and prediction of athletes and their future level of success within a given athletic activity.

References Schniedman, N. (1978) . The Soviet Rad to Olympus - Theory and prac-

tice of Soviet Physical Culture and Sport. Ontario: Ontario Institute tor Studies in Education.

Grabiner, M. D. and Dillman, C. J. (1982) . A program of athletic profiling and counseling. Proposal prepared at the University of illinois Biomechanics Research Laboratory.

Grabiner, M . D . and Dillman, C. J. (1984) . Athletic profiling and counseling- A feasibility report. In Proceedings of "Children to Champions" , An International preOlympic Symposium, (J . Callaghan, Ed .). University of Southern California Press.

Figure 1 Re pre se ntative profiles f o r differe nt athl e t e s 3.5

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Technique

THE ROAD TO SEOUL STARTS IN SALT LAKE PRE

SEN

T

N G:

u.s. OLYMPIC

GYMNASTICS TRIALS JULY 29 THROUGH AUGUST 6,1988 ee the best of America in the Salt Palace as Salt Lake City hosts the top 60 Olympic hopefuls. A men's and women's gymnastics team, along with a rhythmic gymnastics team, will be selected to go for the gold as the United States Olympic Gymnastics Team in Seoul, Korea! Gymnasts will compete in a broad variety of events, including floor exercise, pommel horse, still rings, vaulting, parallel bars, horizontal bar, balance beam, and uneven parallel bars. In addition, enjoy the elegance of rhythmiC gymnasts competing for a spot on the Olympic squad.

S

SCHEDULE OF EVENTS: Rhythmic Preliminaries .. . . July 29 Rhythmic Finals . .. .. . .... July 30 Practice Days . ...... August 1 & 2 Men's Compulsories . ... . August 3 Women's Compulsories .. August 4 Men's Finals . ......... . August 5 Women's Finals ..... . .. August 6 Note: Tentative schedule - dates may VB/}'.

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HOSTED BY:

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Uoited States Gymnastics Fedemtion

~m~mu

CALENDAR

EVENT SCHEDULE (Dates & Events subject to change or cancellation) 1988 April 1-2

May

15-17

USGF Collegiate Nat'l (Division II&III-MIW) International Tournament 01 Cottbus (M) U.S. Rhythmic Gymnastics Championships USA vs Spain (Junior Boys) NCAA Regionals rNl NCAA National Championships (M) Class I State Championships

16-21

rNl MoSCCIN News (R)

20-26

Messe Cup (MIWIR)

21-26

Training in Moscow (R)

22-23

NCAA National Championships rNl McDonald's Challenge USA/USSR (MIW) USA/USSR Exhibition

5-11 8-10 8-18 9-10 15-16

23 24

24-May 1 International Tournament 01 Beijing (M) 27-May 1 Senior Men's Training Camp 29-May 1 Class I Regionals rNl 3O-May 7World Sports Fair (M)

6-8

San Ralel, CA

13-14

Madrid, Spain Various Sites Lincoln , NE

13-15

Regional Elite Qualifying Meets rNl J .O . East Championships (Class Q J .O . West Championships (Class I) Corbeil Essones (R)

21-23

American Classic Nationals

Various Sites

13-14

rNl 14-Jun 5 Four Continents Training Camp (R) Golden Sands (MIW) 25-30

Moscow, USSR Hannover, W. Gennany Moscow, USSR Sa~ Lake City, UT Phoenix, ftZ

June 3-5

Los Angeles, CA Beijing, China

3-5

Colorado Springs, CO Various Sites Tokyo, Japan

25-30 27-28 28-30

3-5

3-8 5-12 18-19 20-24

Junior Olympic Boys NationaisAlbuquerque, NM (M) Santiago City, Moncada Cup (MIW) Cuba JRlSR Training Camp - a as- TBA sic Qualifier rNl Canada Canadian Classic rNl

20-23

Springfield, MA Cottbus, GDR

Various Sites 21-28 Worthington, OH San Jose, CA

23-26 TBA

Corbeil, France Phoenix, ftZ TBA

Varna, Bulgaria Grand Prix 01 Madrid (MIW) Madrid, Spain Japan Brother Cup (R) Junior Olympic Nationals rNl Forest View H.S.-IL

Ohio State University 01 Iowa Arizona State Elite East Qualifying Meet rNl Wilbraham , NJ Elite West Qualifying Meet rNlFort Worth, TX Las Vegas, Jefferson Pilot Olympic NV Promotion Four Continents ChampionToronto, ships (R) Canada U.S. Classic Nationals rNl TBA 'SR Womens Training Camp TBA Sr. Elite Regionals (M)

rNl

July 1-8

Jr. Pan American Games (MIWIR) 7-10 McDonald's U.S. GymnastiCS Champs (MIW) 1989-92 JR Olympic Compul14-19 sory Routine Filming 19-26 SR Elite Training Camp (R) 26-Aug 2 JR Elite Training Camp (R) August 2-9 4-7 5-7

Class I Training Camp (R) Olympic Trials (MIWIR) JR. Intemational Invitational (MIW) Class II Training Camp (R) Jefferson Pilot Olympic Promotion

9-16 13

Puerto Rico Houston , TX Indianapolis, IN Marquette, MI Marquette, MI

Marquette, MI Salt Lake City, UT Cuba Marquette, MI Charlotte, NC

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..

Microcomputer software for gymnastics scoring, written exclusively for the United States Gymnastics Federation.

• Fo r IB M and IB M 100% co mpatable mi croco m puters (with 2 fl oppy d isc dri ves o r ha rd d ri ve) • H andles 60 tea ms and 999 gy mn as ts pe r compe titi on • All USG F Jr. O lympic age group di visio ns • Compulsory O nl y o r Compulsory/O ptiona l CO mpetitIOns • T ea m scoring • All-Aro und Res ults page includes a ll gy mn as ts' plac ings on all events • Co nfigured fo r your hardwa re • Program sup po rt and service provide d by I/O D atabasics o n all sales

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USGF Me rchan dise P .O. Box 5562 Indianapolis, IN 46255-5562

14

I I

Address ________________________________________

I

Co mputer make _______ model Printe r make ________________ model Fo r c redit ca rd only, call 0 Visa 317/23 7-5060 0 Mas te rCa rd Ca rd N umbe r _ __ __ __ ____ Exp. _ _ __

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Technique

Saturday, April 9, 1988 Thcson, Arizona - 8:00am-3:00pm Thcson Parks and Recreation 900 South Randolph Way Thcson, AZ 85716 Course Director: Stormy Eaton - 602-941-3496 Local Contact: Ray Hoyt - 602-791-4870/4879

U.S. GYMNASTICS FEDERATION SAFETY CERTIFICATION TESTING Everyone Needs To Be Safety Certified 1. Promotes a safer teachingllearning environment.

2. Reduces insurance premIUms. 3. Identifies your commitment to your profession, your sport and your athletes.

4. Implementation of stricter safety practices will help reduce the chances of accidents and/or injuries .

5. Helps in membership recruitment.

General Points of Information

1. The text book for the Certification Course is the USGF GYMNASTICS SAFETY MANUAL. This text/reference manual is to be purchased and studied prior to course participation.

2. The course will take approximately six hours, including the test.

3. The Course fee is $100.00 (retest cost is $25.00).

4. Certification is good for four years.

Participation Registration Form Name: Mr .!Mrs .!Ms. Address: _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ City: _ _ _ _ _ _ _ _ State.:_ _ _ _ _ _ __ Telephone: 1.!.(H.!..)L-_ _ _ _--'(l-"'B:.J...)_ _ _ _ __ Course Director: _ _ _ _ _ _ _ _ _ _ _ __ Course Location: _ _ _ _ _ _ _ _-'='D~a~te'-'-:_ __ Organization Represented : _ _ _ _ _ _ _ __

If USGF Member, List Type and Number: _ _ __ Form of Payment: Check Visa Mastercard _ _ __ Name on Card: _ _ _ _ __ __ _ _ _ __ Number: _ __ _ __ _ _ _ _ _ _ _ _ __ Expiration Date: _ _ Signature: _ _ _ _ _ __ Please make checks payable in full to: USGF SAFETY CERTIFICATION Mail Registration Form and Pay ment to Respective Course Contact. '~O

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Registration Form Received: _ _ _ _ _ __ __ Confirmation Mailed: _ _ _ _ _ _ _ _ __ _

Sunday, May 1, 1988 Boont<m, New Jersey - 1O:00am-5:00pm Sokol USA 301 Pine Street Boonton, NJ 07005 201-538-2817 Course Director: Cathy Finkel - 201-263-1534 Course Contact: Geri Johnston - 201-762-5222 Friday, May 13, 1988 Bartlesville, Oklahoma - 2:00-9:00pm Park Inn Hotel, Corral Room - 918-333-2100 222 S.E. Washington Blvd.

(US 75 near 60 West) Bartlesville, OK 74006 Course Director: Eddie Smith - 501-443-1902 This course will be conducted during the Region III Men's Regional Championships.

Saturday, June 4, 1988 Memphis, Thnnessee - 9:00am-5:00pm Lausanne School Library (adjacent to gym) 1381 Massey Road Memphis, TN 901-683-5233 Course Director: David Neel - 901-362-3466 Course Contact: Karen Wener - 901-362-3466 This course will be held in conjunction with the Thnnessee State Coaches Meet.

Saturday, June 5, 1988 Pittsburgh, Pennsylvania - 10:00am-6:00pm National School of Gymnastics 97 Thrence Drive Pittsburgh, PA 15236 412-655-0424 Course Director: Jeannette Jay - 412-563-4161 Friday & Saturday, June lO & 11, 1988 Fort Worth, Thxas - 7:00-1O:00pm both evenings L.D. Bell High School Course Director: Dr. Gerald George 318-988-1220 Local Contact: Jerry Milan - 817-571-0271 x 265 This course will be conducted concurrent with the 1988 USGF International Coaching Summit.

Thesday & Wednesday, June 14 & 15, 1988 East Stroudsburg, Pennsylvania - 7:00-10:00pm both evenings International Gymnastics Center Course Director: Dr. Gerald George 318-988-1220 Course Contact: Bruno Klaus - 717-629-0244 This course will be conducted concurrent with the 1988 USGF International Coaching Summit.

Dates, Times and Locations will all be listed in USA G.YMNASTICS and USGF TECHNIQUE. They can also be checked by calling the USGF Department of Safety and Education at (317) 237-5050

Rhythmic Gymnastics Update Group Exercises: With 3 Hoops And 3 Ribbons Following questions were raised by some Federations regarding the group exercise with 3 ribbons and 3 hoops, the Technical Committee of RSG/FIG would like to clarify the following: 1. The composition of the group exercise must clearly represent the elements specific to these apparatus and the body movements specific for each apparatus.

2. Regarding the ribbons: 2.1. the individual gymnast can perform movements of the ribbon by holding the apparatus by the stick and by a part of the ribbon, with one or two hands.

Consequently, the gymnasts of the group can perform movements of the ribbon in which a gymnast holds the apparatus by the stick while another gymnast holds it by the ribbon.

2.2 The norms regarding the use of the apparatus as a decoration or the static use of the apparatus are still valid. However, a stretched ribbon (or

stretched ribbons), held by one, two or several gymnasts in order to obtain geometrical designs without specific movement of the ribbon, can be tolerated under the following conditions: - the static and choreographic use of the ribbon (or ribbons) can be justified by specific moves of the hoops. If this is not the case, it constitutes a non-authorized choreographic element, for which a penalty of 0.30 point is applicable.

- the static and choreographic element of the ribbon must be very momentary. If this is not the case, it constitutes a static use of the apparatus, for which a penalty of 0.20 points is applicable.

2.3 A maximum of three such elements will be tolerated in the composition. Penalty: 0.20 point for each supplementary element.

Group Exercises: Musical Accompaniment Subsequent to certain errors noted at the 1987 World Championships at Varna in the utilization of the new possibilities of accompaniment for the group exercises, the TC-RSG-FIG points out that the use of 2 or 3 different musics is acceptable .

However, where it is a question of arrangements, of music specially rewritten for the exercise or of musical "editing", the following rules must be observed: 1. The different musical themes must be linked and their co-existence must be as unified as possible.

2. An interruption of the music between 2 different themes is not permitted.

3. In the case of "editing", the tonalities of the various musical themes must be respected as well as the phrases and the musical themes themselves.

USGF Official Gymnastics Safety Manual. "' -

-

Official manual for USGF Safety Certifica tion Program Designed to raise the level of safety awareness in the entire industry.

-

Includes chapters on: The Need for Safety; Legal Responsibility of Instructor; Accident Prevention

U.S. G~ASTICS FEDERATION A Must For Every Serious Gymnastics Professional To order eith e r th e Gym nas tics or Trampolin e Sa fe ty Man ua ls, se nd ch eck or money order to: USGF Me rcha ndi s in g P.O. Box 5562 In d ia napol is, India na 46255-5562

#6001 USGF Safe ty ma nu al (q ua nt. ) _ _ x $16 .45

= __

#6002 Trampolin e Safe ty Man ua l (q ua nt. ) _ _ x $ 9.95 A ll ow 4-6 weeks for delivery.

Edit ed by

Gera ld S. George, Ph .D.

16

= _

_

Total amo unt encl osed _ _ Edited by Wi lli a m A lli so n

Technique

Survey To Help Loss of Athletes DEAR GYMNAST, As the Age Group Chairman for Region VIII, I am extremely concerned with the loss of high level competitors from our sport . As a result of this concern, I have devised the enclosed questionnaire for yourself and your parents to fill out and return to me.

I am not asking you to consider returning to competitive gymnastics, but to possibly identify some of the causes that led to your leaving.

All responses will be marked confidential, and your

name, parents name, coach or gym name will not be mentioned. Please enter your Region and State abbreviation for your code number, for example 4-IA if you are from Iowa (Region IV).

Thank you for your help, we all miss you and wish you well in your future endeavors.

Please send this form to me at 730 St. John's Bluff Road, Jacksonville, FL 32211 (904) 641-9966 .

D .J. Milem Regional Jo Development Chairman

CODE NUMBER _ _ _ _ __ (NOTE: Please use separate sheet of paper for additional comments) 1.

2.

3.

4.

5.

6.

Your present age? _ _ _ _ __ How long were you in gymnastics (Classes, etc.),_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ How long were you in competitive gymnastics?_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Your highest level of competitive gymnastics (Elite, Class I, etc.), _ _ _ _ _ _ __ __ _ _ _ _ _ _ _ _ __ What was your most enjoyable level?_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ Why do you consider this the most enjoyable?_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __

7. Time spent at your last competitive level?_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ 8. Why did you move up/down to your last competitive level (coaches decision, mandate, your friends all moved up, mom & dad wanted it, etc.)? _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __

9.

10.

11.

12.

13.

14.

15.

Your age when you quit? _ _ _ _ __ Your grade in school when you quit? _ _ _ _ __ Were your grades in school affected by the time spent in gym? Y - N How many hours per day did you spend in the gym? _ _ _ _ __ How many days per week? _ _ _ _ __ Did you have weekend workouts? Y - N - SOMETIMES If Y, did you have to attend or did you have a choice? _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __

16. How did your friends (other than friends in the gym) view your time spent in the gym? Felt that you spent too much time doing gymnastics. Thought that it was neat that you could do that stuff, etc ._ _ _ _ _ _ _ _ _ _ __ 17. Were you a cheerleader in your school prior to quitting gymnastics? Y - N Sisters _ _ __ 18. Do you have brothers and sisters? Y - N No . Brothers 19. If Y, did your brothers or sisters seem to resent the fact that you took up so much of your parents time (driving to gym, going to meets, etc.?) Y - N 20. Did you feel that the difficulty level at the last competitive level was too hard? Y - N 21 . Were you injured prior to your decision to quit? Y - N 22. Was that one of the reasons you quit? Y - N 23. Was your weight one of the reasons you quit? Y - N 24. Did it seem that all of your team mates and the little kids got tricks easier than you did? Y - N 25 . Did your coach seem to ignore you, and favor the others? Y - N 26 . Did you change gyms before you decided to quit? Y - N 27. Did gymnastics just not seem "FUN" anymore? Y - N 28. Did any of your team mates decide to quit with you? Y - N 29. Were you hoping to use your gymnastics to get a college scholarship? Y - N 30. Any other reasons for your decision to quit? _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __

Technique

17

An Insight Into The Biomechanics Of Twisting By: Hardy Fink Department of Physical Education University of British Columbia Introduction n understanding of how a gymnast twists in the air is still not complete, even in the minds of physicists and mathematicians; however, the past decade has seen much progress in identifying probable mechanisms and in identifying which of these mechanisms are most effective or contributory to successful twisting.

A major problem has been that, although the human body must obey the laws of physics, it does not act as a rigid system and therefore is not easily analyzed. In fact, a recent survey (Frohlich, 1979) of the 59 physicists who responded to a questionnaire, more than 56% believed that a somersaulting diver could not initiate a twist after having left the board; something we practitioners have known to be readily possible for some time.

Ten years earlier a paper was published (Leigh & Bengerter, 1967) which attempted, with the use of cinematography, to demonstrate that coaches were poorly prepared in basic theory because all in the study believed (probably correctly) their divers and trampolists to have initiated their twists in the air, contrary to what the authors believed the film to show.

The reasons for past difficulties are not hard to understand . All "knew" that according to the principle of conservation of angular momentum rotation could not be initiated in the absence of an applied torque. Also, until the late '60's not many aerial performances, in the sense of multiple somersaults with delayed multiple twist, had been seen; the common appearance of which finally did challenge theoreticians to explain. Finally it may well be, and the issue is far from resolved, that as many as three or four twisting mechanisms are active during one performance and that these mechanisms may interact throughout a complicated twisting and somersaulting performance.

Twisting Mechanisms

A

For purposes of Simplification, validated twisting mechanisms may be identified in the following manner: A. Torque twists B. Non-torque twists I. Zero Angular Momentum Mechanisms a) "cat twist" or two axis theorem b) "hula hoop" or conical twist II. Non-Zero Angular Momentum Mechanisms a) " tilt twist" 18

Understanding Angular Momentum The principle of the conservation of angular momentum is most simply stated as: Angular momentum = moment of inertia x angular velocity or AM = Iw For meaningful discussion the forgoing relationship must be understood completely.

1. Angular momentum can be viewed as the quantity of rotation a body has about some given axis as a result of its speed of rotation and the distribution of mass about the axis.

Technique

2. Moment of Inertia (I) is a measure of how the mass of a body is distributed about the axis of rotation.

The further the mass is away from the object the larger the I and vice versa. In fact I increases as the square of the distance of the mass and therefore small increases in distance can result in relatively large increases in I. 3. Angular velocity (w) is simply the speed of rotation about the axis of rotation.

4. Since AM must be conserved (unless an external force or torque is applied) the product of I and W must stay constant. However the human body can change position in the air whch has the effect of changing I and thus w. If a gymnast tucks up in the air I will decrease and then, so that AM be conserved, W will increase accordingly and vice versa.

5. No discussion of rotation is meaningful unless the axis of rotation is specified.

Angular momentum can be created only by the application of an eccentric force - that is, a force that acts at some distance from the axis of rotation . Such a force is known as a torque and is most effective the further that it is applied from the axis.

Twisting Mechanisms A. Torque twists: Clearly the most effective twisting mechanism is to apply a large torque relative to the longitudinal axis during take-off. The gymnast will then have a considerable twisting AM in the air and then if the arms have been held wide (large I) W can be increased quite significantly simply by pulling the arms in (small I) .

For most twisting gymnastics skills the application of a torque during take-off is the major twisting mechanism.

B. Non-torque twists: Two conditions can occur: The gymnast can begin with total body AM equal to zero about all axes or the gymnast can begin with some quantity of AM about one of the non-twisting axes (ie. somersaulting or cartw heeling).

1. Zero AM Twisting Mechanism: Two quite different mechanisms have been identified that provide for a body twist without violating the principle of conservation of angular momentum. a) "Cat-twist" or two axis theorem It is possible to perform a limited twist by varying the relative moments of inertia of the upper and lower body - in essence successively twisting one part of the body with small I against one with large I which will therefore twist less in the opposite direction. b) "Hula-hoop" or conical twist theory The simplest explanation is that if a body part is used to introduce an extraneous component of AM the total body must turn in the opposite direction to maintain the total AM at zero . The hand or arms could be rotated overhead but more effective because of its mass is to use the trunk in a "hula-hoop" fashion. The total body will respond by twisting in the opposite direction about the longitudinal axis .

It is important to recognize that these mechanisms, under conditions of zero total body AM, provide only for a reorientation of the body in Technique

space while certain body parts are moved and that the twisting action ceases immediately that the body actions are stopped.

II. Non-zero AM Twisting Mechanism a) "Tilt twist" If a gymnast has considerable angular momentum about the tranverse (somersaulting) axis it has now been established that the most effective mechanism for initiating a non-torque sustained twist is what is commonly referred to as the "tilt twist." This took many years to "discover" because it had been neglected that AM is a vector quantity - that is, it has a magnitude component and a directional component. For AM to be conserved both components must be conserved. The direction of the angular momentum vector during a somersault is along the axis of rotation (left for forward "somies" and vice versa) .

The tilt mechanism requires the gymnast to shorten one side of the body relative to the other (by throwing the arms-one up, one down - or by side flexion or both). This has the effect if tilting the somersaulting axis away from the AM vector which direction, in order to be conserved, requires the body to undertake a compensating sustained twist about the longitudinal axis as long as the "tilt" exists.

Though this is not a mathematical paper, the simplified mathematics of what occurs can be very enlightening.

AMt = AMs sinO Itwt = IswssinB Wt = Ws (Is I It) sinO where t

= twist,

s

= somersault, a = angle

(1) (2) of tilt

Equation (1) gives the relationship of how much twisting AM is induced by a given degree of tilt, but Equation (2) is especially useful once it is understood. If we assume that we wish to maximize the speed of the twist (Wt) then the equation tells us the following : 1. Wt will be larger the larger the Ws (the speed of the initial somersault) .

2. Wt will be largest if the somersaults are performed in the layout position since the value of IslIs is maximized if the numerator is maximized and the denominator minimized (a layout position in each case).

3. Wt will be greatest the greater the amount of tilt or the greater the amount one side is shortened relative to the other since the value of sine increases from a to 1.0 as the angle e approaches 90 째. In other words if the body tilts sideways (8 = 90 째; sine = 1) completely then the total somersault is converted to twist.

The message should be clear. One of the most effective uses of the tilt twist mechanism is in multiple layout somersaults with late twists (i .e. double layout with full out) which gives a large value of WSt maximizes the value of Is/I t and perhaps of sinO because of the arch to hollow body position change.

It has been demonstrated that in backward somersaults the feasible tile of 10째 will result in a twisting speed of 3 twists for each somersault. Forwards the feasible tilt is 20째 which can result in 5% twists per somersault.

19

Conclusion It is likely that in most twisting gymnastics skills there is an interaction of the various twisting mechanisms.

Although the "cat twist" and the " hula hoop" mechanisms were explained in reference to zero angular momentum twists, it is clear that they may also be active in nonzero angular momentum twists. In these cases the " cat twist" likely assists in initiating twist and the "hula hoop" mechanism assists in and may be sufficient for sustaining it although it is not clear if these actions can be maintained consciously throughout a complex performance .

In all cases - other things being equal - a torque twist is the most effective twisting method provided it does not aesthetically detract from the performance or result in the modification of other performance parameters (i.e . height or somersaulting AM). In delayed non-zero AM twists the "tilt twist" mechanism is the most effective and the only one that can create a sustained twist. It is also the only in air mechanism that is certainly under conscious control during the initiation and maintenance of complicated twisting skills .

REFERENCES

Bartee, H . & Dowell, L (1982) "A cinematographical analysis of twisting about the longitudinal axis when performers are free of support," Journal of Human Move4~ ~ _ •

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Fink, H. (1985) "A critical review of biomechanical research in the sport of gymnastics," University of British Columbia, unpublished paper.

Fink, H. (1986) "The principle of the conservation of angular momentum and its application to gymnastics, " Coaching Review, March, 1986.

Frohlich, C. (1979) "Do springboard divers violate angular momentum conservation?" American Journal of Physics, 47(7) : 583-592.

Leigh, L. & Bangerter, B. (1967) "A cinematographic analysis comparing techniques and mechanics of selected forward and backward twisting somersaults in competitive diving and rebound tumbling." Paper to A .A.H.P.E .R., March 13, 1967.

Liu, Z. & Nelson, R. (1985) " Analysis of twisting somersault dives using computer diagnostics" in BIOMECHANICS IX-B Frohlich, C. (1980) "The physics of somersaulting and twisting," Scientific American, March, 1980.

Van Gheluwe, B. (1981) " A biomechanical simulation model for airborne twist in backward somersaults" Journal of Human Movement Studies, 7:1-22.

Van Gheluwe, B. & Duquet, W. (1977) "A cinematographic evaluation of two twisting theories in the backward somersault," Journal of Human Movement Studies, 3:5-20.

Yeadon, M. & Atha, J. (1985) "The production of a sustained aerial twist during a somersault without the use of asymmetrical arm action" in Biomechanics IX-B (ed.

by Winter et al), pp . 395-400.

20

Technique

NATIONAL USGF TEAM T路SHIRT LOGO PIN

e

Wear your sport on your shirt.

The new national team logos are presented in Red and Navy on a 50/50 cotton t-shirt.

9101-9107 Women's National TeamT 9201-9207 Men 's National TeamT 9301-9307 Rhythmic NationalTeamT $7.95

USA SWEATSHIRT This soft white sweatshirt is embroidered with USA in red and Gymnastics in blue. Perfect for your favorite gymnast.

5311-5317 $22.95

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GO\O~

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Perfect for carrying all your stuff to the gym . This navy nylon bag is 18 x 10 with white straps and the USGF logo in red and white.

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GYMNASTICS SAFETY

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SECQ

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INTERNATIONAL I I COACHING SUMMIT I Featuring Men's And Women's Gymnastics

ome participate in a three-day coaching seminar for men's and womf>n's 2:vmnastics with top- clinicians from th~ United States and Soviet Union.

C

FEATURES • Two coaches and gymnasts from the United States and Soviet Union present at all sessions.

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TWO SESSIONS June 10-11-12, 1988 Ft. Worth, Texas L.D. Bell High School

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1

1\LWAYS VIDEO

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n an effort to upgrade safety awareness in the gymnastics community, the United States Gymnastics Federation has developed a safety video, that gives athletes, coaches and club owners easy and enjoyable method of disseminating safety .!_J:. ~

_ _ L..!~_

1J.lJ.VJ.J.llQUV.ll.

Featuring Olympic gold medalist Bart Conner and Peter Vidmar, along with silver medalist Kathy Johnson, Abie Grossfeld, Greg Marsden, Judy A vener and Bela Karolyi.

Truely a state of the art method to teach gymnastic safety and awareness.

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Because our concern rests with the athlete.

Because we believe gymnastic apparatus should enhance an athlete's performance, never hinder it.

It's no wonder American Athletic is the choice of champions. Shouldn't it be your choice, too? Bring out the best in your athletes, bring out MI American.

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