Biomechanics and Medicine in Swimming XI

More documents

Recommendations

Info

The Construct Validity of a Traditional 25m Test of Swimming Competence Junge, M. 1,3 , Blixt, t. 2 , stallman, r.K. 1,4 1 Norwegian School of Sport Science, 2 Norwegian Swimming Federation, 3 University of Oslo, 4 Norwegian Life Saving Association A universal definition of the ability to swim has yet to be agreed upon. Some believe that “how far” one swims is the most important criterion. The number of meters is controversial. Some use a traditional definition of from 25m to 200m, often as the only criterion of “can swim”. In fact, this is not the point. A conceptual model emphasizes broader competence. The result of this model is a combined test including more than only distance. This combined test was used as the criterion to test the construct validity of a traditional test. When these two tests were compared they were found to be very different, thus measuring different qualities. Among children already declared able to swim by the traditional test, only 5.7% satisfied the conditions of the conceptual test. It was concluded that the traditional test was not a valid measure of the ability to swim. Key words: evaluation, swimming competence, validity, distance test IntroductIon Learn to swim programs remain dramatically different in their content and in the manner in which the learner’s progress is evaluated, in other words, by which criteria a child is judged “able to swim”. There is fortunately, growing agreement among researchers and educators on the importance of a) breath holding, breath control, b) floating, buoyancy control, c) gliding and postural control, and d) stroking and directional control, as well as orientation, balance and rotation (Stallman, et al, 2008). These are seen as essential, core elements. There remain however, many ideas about how and what a child should learn. The less experienced person (school teacher who is not a swimming instructor, parent, significant other) is more prone to fall prey to misconceptions. In a recent Scandinavian questionnaire investigation, it was revealed that almost every primary school head master had her/his own definition (Directory of Education, Norway, 2008). There also remains a traditional notion that the number of meters achieved is the only or most important criterion for defining the ability to swim. This is especially true among parents but sadly, remains common also among certain swimming instructors. A common complaint is that “we don’t have enough time”. The result is often a single selected stroke and a pre-determined distance (Directory of Education, Norway, 2008). The notion that some form of all around development is more important than simply a certain number of meters seems to have escaped closer scrutiny. A number of well known and respected national agencies (e.g. The American Red Cross, The German Life Saving Association, etc.) have long emphasized all-around development as essential in drowning prevention. The concepts of “watermanship” or “aquatic competence” are well known (Sinclair & Henry, 1893, Langendorfer & Bruya 1995). Both Cureton (1943) and the USA Navy (1943), emphasized that drowning can take many forms, and that these are unpredictable. Therefore, many solutions (all-around development) are necessary to solve many possible life threatening situations. When considering the ultimate negative outcome of an aquatic “episode” (death by drowning) it is clear that a variety of skills is required to cope with the wide variety of possible situations in which an unsuspecting person might find themselves – in the water. It surely is obvious then that, one stroke or one distance is not sufficient. Unfortunately, some still appear to believe it is. And the discussion goes on, 25m, 100m, 200m? And of course, whatever conclusions one reaches about skills, we also tend to neglect knowledge, attitude and judgment. chaPter5.education,adviceandBiofeedBack The motive for this study was thus to examine the idea that it is not how far but how one swims that really matters. The aim of this study is thus, to examine the construct validity of a 25m test of swimming competence by comparing it with a criterion combined test, maintaining the same overall distance on both. It was also assumed that the same results would appear if a different distance had been chosen. For example, that a traditional test of 200m with single stroke is not the same as a 200m combined test with the same pattern as the shorter combined test. Method From among 200 primary school children, age 9&10 years, taught in a single school term, 70 succeeded in the local traditional test of negotiating 25m with no other criteria. These 70 were declared “able to swim”, awarded a pin and the parents were notified that their child could swim. These children (N=70) constituted the subjects of this study. By performing a second test, within 3 days of the first, they served as their own controls. The criterion “combined test” consisted of: a) jump or dive into deep water (3m), level off, b) swim 12.5 m in the prone position c) turn 180 degrees, d) roll over e) rest for 30 sec with minimal movement, f ) swim back to the starting point in the supine position. Diving was awarded two points, jump one point and 0 for those who refused both jump and dive. Each of the other elements was awarded two points. The maximum possible score was thus 12 points. The total distance was the same for both tests but the criterion test was obviously more comprehensive, included a more balanced skill profile. The children were motivated by being offered a second, new award. No mention was made of the second test being a test of swimming ability nor was it implied that the first test was anything other than what they had believed it to be. To any direct question, the second test was simply referred to as a “new” test, and new award; swim or swim better. The children were tested by their own teacher to avoid bias by altering the atmosphere. The observers who evaluated the performance were known to the children. The children were tested four at a time and each of two observers was assigned to two children. The same observers evaluated all of the subjects. Pilot testing was conducted to train the observers. Discussions were held to ensure that both observers used the same criteria. A head instructor coordinated all evaluation and made the final decision in any case not obvious in its outcome. Each element was scored and the total score was recorded. The results were tabulated by frequency distribution and both the number and percent of subjects succeeding on each element was recorded. The total scores were also recorded The criterion test was the result of a construct, i.e. a conceptual construction based on the logical arguments cited above. If these two tests gave similar results, the traditional test would be accepted as having construct validity. If the two tests differed they would be considered to measure different qualities and the traditional test would be considered not to have construct validity. results Table 1 shows the results by element. The results clearly show that all but the one element reproduced also on the first test, were not mastered by many of the children. Table 1 Success by element on the combined criterion test Test Item Number (n = 70) % 1. Dive 16 23 Jump 36 51 Start in water 18 26 2. Swim 12.5m prone 70 100 3. Change direction 1800 63 90 4. Roll over 40 57 5. Stop & rest 30 sec. 4 6 6. Swim 12.5m supine 36 51 331
BiomechanicsandmedicineinswimmingXi As would be expected, 100% of the children who had already swum 25m on the front, succeeded in swimming 12.5m on the front. However from that point on, fewer managed the other elements. Twenty six percent refused to either jump or dive into deep water, asking to start in the water. Ten percent did not manage to change direction. Forty three percent were unable to roll over. Forty nine percent were unable to swim on the back. And lowest of all, only 5.7% managed to stop and rest, even for only 30 seconds. The range of total scores was from 4 to 12. Only four of these pupils scored 11 or 12 points, i.e. by the criterion test, could swim. dIscussIon The real issues here are, how do we evaluate whether a child can swim or not, and can a simple distance test serve the need to evaluate. To return to the idea that it is how one swims rather than how far, we must forsake traditional ideas of any given distance. Some insist on 25m, some on 200m, others are somewhere in between. It can be remembered that the Scouting movement has long operated with a 200yd (ca 180m) minimum before permitting boating activities (Scout Handbook, 1956). Several national life saving organizations also have a tradition of focusing on 200m or 200 yds. In some cases, no other criteria are used. Can it be that one who can swim 200m but not 201m, can swim? How safe is this person? How are they prepared for the many possible scenarios one might be victim to in an involuntary submersion? The results of this study show clearly that the two tests considered, measure different qualities. Being able to swim 25m non-stop on the front does not automatically give one the ability to swim in the back, turn, roll over, stop and rest or jump or dive into the water. (if an emergency required one to swim on the back or to stop and rest (gather ones wits, catch the breath, settle down, re-orient oneself ) as it might well do, these subjects would be in serious difficulty. They are clearly, not Biomechanics as safe as they and might Medicine have in been Swimming if they XI had mastered the criterion 54 Chapter 5 Education, Advice and Biofeedback test. Consider the statistic cited by Golden and Tipton (2002), that > 40% of drownings in the UK happen within 3m of safety. The logically matching give one scenario the ability would to swim require in the back, victim turn, to turn roll over, around stop and and make rest or jump or dive their into way the water. back to (if safety. an emergency Cold shock required also first one described to swim clearly on the by back these or to stop and rest same (gather authors, ones wits, operating catch within the breath, seconds settle of submersion down, re-orient and dramatically oneself) as it might well do, these subjects would be in serious difficulty. They are clearly, not as safe as they might raising the respiration rate, reducing air exchange and raising the HR, have been if they had mastered the criterion test. Consider the statistic cited by Golden requires and Tipton clearly (2002), the quality that > 40% of being of drownings able to stop, in the rest, UK take happen stock, within catch 3m of safety. The the logically breath, matching etc. It remains scenario a mystery would to require us that the the victim ability to to turn stop around and rest and make their way is back so often to safety. ignored Cold or underestimated. shock also first described clearly by these same authors, operating within To accommodate seconds of submersion the desire and to keep dramatically some semblance raising the of distance respiration as rate, reducing air a exchange useful skill and (attitude?), raising the it HR, is only requires logical clearly to suggest the quality that of the being criterion able to stop, rest, take combined stock, catch test the examined breath, etc. in this It remains study, can a mystery easily be to expanded us that the to ability greater to stop and rest is so often ignored or underestimated. distance while retaining the same pattern. An example might be a total To accommodate the desire to keep some semblance of distance as a useful skill of (attitude?), 100m (50 it + 50) is only with logical a 60 sec. to rest suggest and perhaps that the a criterion more demanding combined way test examined in this to study, fall into can the easily water, be or expanded 200m (100 to greater + 100) distance with a 3 while min rest. retaining Clothing the same pattern. An could example (and might should) be be a total added of to 100m increase (50 the + 50) challenge. with a 60 Stallman, sec. rest et and al. perhaps a more (2008) demanding introduced way to the fall idea into that the “Can water, Swim” or 200m is not (100 a sharp + 100) demarcation with a 3 min rest. Clothing from could “Cannot (and should) Swim” be but added rather to increase a zone in the which challenge. we can Stallman, describe et can al. (2008) introduced swim the idea at a that minimal “Can level Swim” and is progressively not a sharp at demarcation higher levels. from Can “Cannot and Can Swim” but rather a Better. zone in See which Fig 1. we can describe can swim at a minimal level and progressively at higher levels. Can and Can Better. See Fig 1. T-shirt shirt trousers shirt & trousers etc 2 strokes 3 strokes 4 strokes 5 strokes, etc 30 sec rest 1min rest 2 min rest 3 min rest, etc 25m 50m 100m 200m etc Fig. Fig. 1 A graded graded approach approach to to “Can “Can Swim” Swim” In Northern Europe there exists a certain feeling about swimming on the back, insisting for example that in a 200m test, only 50 need be on the back. This is to 332 denigrate the value of a life preserving skill. And often no other criteria are used. The combined test approach presented here as a construct, is a balanced one. To focus on any distance is to avoid the issue. It is not a question of how far or which stroke. The child who is relaxed in the water and uses their natural buoyancy, is In Northern Europe there exists a certain feeling about swimming on the back, insisting for example that in a 200m test, only 50 need be on the back. This is to denigrate the value of a life preserving skill. And often no other criteria are used. The combined test approach presented here as a construct, is a balanced one. To focus on any distance is to avoid the issue. It is not a question of how far or which stroke. The child who is relaxed in the water and uses their natural buoyancy, is able to control breathing, is able to stop and rest, is safer at 25m than the child who can swim 100m but does so only non-stop and with great effort. The first named child can swim 25, stop and rest, swim 25 more, etc and soon accumulates a greater distance than her/his counterpart. Those who focus on distance only, see only the result and lose sight of the process. Here the reader is reminded that a common attitude among less experienced instructors is that technique is not important, most children never become competitive swimmers. The real issue however is that economy of effort is often a matter of life and death. Technique in fact, when we consider saving energy by more efficient movement, not overcoming the powers of nature but working in harmony with them, is the most valuable of survival skills. There can be little doubt that the ability to swim 200m indoors in a warm quiet pool, is no guarantee that one can swim the same distance outdoors, in colder and restless, open water, and perhaps fully clothed. But at what ever distance one arrests the learner’s progress, in a laboratory slice of life to be examined under the microscope, the pattern of versatility should be retained. Each element would then be increased to a higher level of challenge. conclusIons The distance test of 25m, with no other criteria, measures different qualities than the slightly more comprehensive combined criterion test. If we accept the construct validity of the criterion test, the traditional test is necessarily judged not to have construct validity. reFerences Cureton, T.K. (1943). Warfare Aquatics, Champaign, IL, Stipes Pub. Directory of Education, Ministry of Education, Norway (2008). The Teaching of Swimming and Life Saving; Support materials for teachers and instructors in the primary school. Oslo, Norway Golden, F. and Tipton, M. (2002). The Essentials of Sea Survival, Champaign, IL. Human Kinetics Higgins J., et al. (1943). Swimming and Diving. The United States Navy. United States naval Institute, Annapolis, MD Hines, F. (ed) (1978). The Scout Handbook, Boy Scouts of America, N.Y. Hurt, H.W. (ed) (1910). Handbook for Boys, Boy Scouts of America, N.Y. Langendorfer, S.J. and Bruya, L.D. (1995). Aquatic readiness. Champaign, IL, Human Kinetics Sinclair A. and Henry W. (1893). Swimming, London, Longmans Stallman R.K., Junge M., Blixt T., (2008). The teaching of swimming based on a model derived from the causes of drowning. Int J of Aquatic Research and Educ, 2(4), 372-382
Page 1 and 2:
Biomechanics and Medicine in Swimmi
Page 3 and 4:
Bibliographic information: Biomecha
Page 5 and 6:
Biomechanicsandmedicinein
Page 7 and 8:
Page 9 and 10:
Page 11 and 12:
Page 13 and 14:
Page 15 and 16:
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Figure 1. General biomechanical par
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
average VO2 measured during resting
Page 219 and 220:
Page 221 and 222:
Fourteen highly trained male swimme
Page 223 and 224:
Page 225 and 226:
Page 227 and 228:
Page 229 and 230:
Page 231 and 232:
Page 233 and 234:
Page 235 and 236:
Page 237 and 238:
Page 239 and 240:
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
Page 247 and 248:
Page 249 and 250:
Page 251 and 252:
Page 253 and 254:
Page 255 and 256:
Page 257 and 258:
Page 259 and 260:
Page 261 and 262:
Page 263 and 264:
Page 265 and 266:
Page 267 and 268:
Figure 2. Repeatability of the LTin
Page 269 and 270:
Page 271 and 272:
Page 273 and 274:
Page 275 and 276:
Page 277 and 278:
Page 279 and 280:
Page 281 and 282: Biomechanicsandmedicinein
Page 299 and 300: -ARM * 5 Biomechanicsandmedic
Page 319 and 320: • Without restriction; • Blinde
Page 331: Biomechanicsandmedicinein
Page 359 and 360: etween experimental groups and cont
Page 383 and 384:
Page 385 and 386:
Page 387 and 388:
Page 389 and 390:
Page 391:
Pahlen Norge AS Pahlen Norge AS Cha
show all

Biomechanics and Medicine in Swimming XI

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?