Biomechanics and Medicine in Swimming XI

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Using a Scalogram to Identify an Appropriate Instructional Order for Swimming Items langendorfer, s.J. 1 , chaya, J.A. 2 1 Bowling Green State University 2 University of Toledo Scalogram, first proposed by Guttman (1950), is a descriptive ordering technique used in the social sciences to investigate how heterogeneous behavioral items may relate to one another in time. In the present study, we explored whether there was a predictable order of acquisition among selected swim skill items used in the instruction of swimming. If so, we might identify a preferred order in which to teach these swim skills. A convenience sample of thirty-one college students enrolled in University instructional swimming classes performed each of the items in random order while investigators videotaped each performance. After establishing inter-observer objectivity exceeding P > 0.80, the investigators observed each video trial and scored each item for each participant as pass-fail using pre-established criteria based on the American Red Cross Swimming and Water Safety learn-to-swim program (Red Cross, 2004). The Red Cross order for teaching the tested skills was confirmed as the best order identified by the scalogram for young adult participants with a coefficient of reproducibility of CR = 0.93. Limitations in the procedures and results suggested the need for several future studies to identify whether the order applied to other ages and ability levels as well as how susceptible the scalogram technique is to varying instructional experiences of participants. Keywords: swim instruction, swimming skills, scalogram, developmental sequences IntroductIon The order in which different human behaviors are acquired has a long history of scholarly interest. Charles Darwin, in his “Biography of a Baby,” chronicled the behaviors and ages he observed his son acquire typical “motor milestones” (Darwin, 1877). Jean Piaget, the noted developmental psychologist and epistemologist, provided detailed descriptions of the order in which his own three children acquired various psychomotor, cognitive, and social behaviors during childhood (Piaget, 1973). During the heyday of infant motor development, developmental researchers such as Arnold Gesell (1940), Mary Shirley (1931), and Myrtle McGraw (1939; 1963; 1975) all proposed different sequences of infant behaviors. McGraw, specifically, focused on the description and order in which infant swimming behavior changes progressively over time (McGraw, 1939). The order with which individuals acquire different skills has implications and importance to different clinicians and practitioners such as teachers and coaches. The logic is that easier tasks should be introduced or taught first. The basis for the developmental task analysis (Herkowitz, 1978; Roberton, 1989) or constraints-based task analysis approach (Haywood & Getchell, 2009) uses a similar logic for structuring motor skills. Developmental task analysis separates motor task factors and then organizes them according to the levels of complexity. In the developmental task analysis scheme, inexperienced performers encounter the least complex movement task factors first and then progressively experience more complicated levels to improve the success of movers. Presumably the acquisition of easier tasks serves to build foundational competence in learners as well as enhance their sense of self-confidence and success. Guttman (1950) proposed an interesting technique called the scalogram for examining the robustness of order of acquisition for series of different behaviors. He proposed to discern item difficulty by examining a heterogeneous sample of individuals who attempted a series of items chaPter5.education,adviceandBiofeedBack which were measured on a pass-fail (or dichotomous) basis. The reasoning behind the validity of the scalogram technique is that the easiest or least difficult items should be mastered by the most individuals because they are acquired first. As item difficulty increases, fewer and fewer individuals should be able to master the task. Consequently, the most difficult and presumably the last items in a series to be mastered will be able to be demonstrated by the fewest individuals. Using a matrix-like table, Guttman (1950) proposed a “coefficient of reproducibility” which represents the average ratio between the total successful responses (or passed items) and the total possible number of responses (or product of items times participants). Like similar association coefficients, the coefficient can range from 0.0 to 1.0. A higher ratio produces a stronger coefficient of reproducibility which indicates a more predictable acquisition order across the items under study. Guttman’s scalogram technique has been used to examine the order of difficulty and acquisition for several types of motor behaviors. DeOreo (1976) studied the order that children acquire balance task items. Prior to the current study, Harrod (Harrod, 1990; Harrod & Langendorfer, 1991) was the only individual to examine the order of acquisition for swimming skills, specifically beginner swim items. Harrod undertook her study to test whether a traditional order of beginner skills proposed by the American Red Cross (1981) was, in fact, the optimal order in which to introduce those swim items. One important result included the discovery that the ten-second breath holding item (American Red Cross, 1981) was one of the hardest beginner skills and should either be shortened or be taught much later to beginners. She also identified that front and back gliding skills were passed by more children than were front and back float items, suggesting that for children it was easier to move and glide than to float motionless. As a result of Harrod’s work, the American Red Cross did revise the order in which some beginner swimming skills (e.g., breath holding) were taught (American Red Cross, 1992). The purpose for the current study was to replicate the findings of Harrod (1990; Harrod & Langendorfer, 1991) with an older age sample and with slightly different swimming items. The study was conducted because the American Red Cross was once again in the midst of revising the learn-to-swim program. The organization has made a commitment to base their practices more closely on evidence-based literature. Method College students already enrolled in academic credit-bearing instructional swimming classes at Bowling Green State University were recruited to participate in our study. From the approximately sixty students enrolled in the courses while we conducted the study, thirty-eight students initially volunteered and thirty-one (n f = 17 females; n m = 14 males) completed testing for all thirteen skill items. Because testing occurred across multiple days, several original volunteers completed only some of the tasks due to absenteeism and were eliminated from the data analysis. Before beginning data collection for the study, the authors submitted a proposal and received approval from the University’s institutional research review board, called the Human Subjects Review Board (HSRB). Prior to participation in the study, each student completed an informed consent form and investigators answered any of questions. Specifically, each student was reminded that participation was completely voluntary, would not influence their grade in the course, and they could end participation at any time with no penalties or consequences. The thirteen specific swimming skill items tested and performance criteria are identified in Table 1. They ranged from several typical beginner skills (Red Cross Levels 1 and 2) such as breath holding, prone and supine floats and gliding to performing more advanced strokes (Levels 3, 4, 5) such as front and back crawl, breaststroke, elementary backstroke, and sidestroke. The specific performance criteria employed in judging the successful achievement of each skill were those described by the American Red Cross in their Swimming and Water Safety Instructor’s Manual (2004). 333
BiomechanicsandmedicineinswimmingXi Table 1. List of swimming skill items tested in the current study and their criterion standards. Swim Test Item Abbr. Criterion Standard Breath holding Breath Submerge entire head and remain submerged a minimum of 3 seconds Prone float P float Float on your front for as long as possible, at least 5 seconds Prone glide P glide Push off on your front and glide forward at least two body lengths Back float B float Float on your back for as long as possible, at least 5 seconds Back glide B glide Push off on your back and glide forward at least two body lengths Combined stroke alternating arm action 334 Comb Alt Dolphin kick Dol Kck Combined stroke simultaneous arm action Comb Sim Front crawl Fr Crwl Back crawl Bk Crwl Elementary backstroke El Back Breaststroke Brst Sidestroke Side Swim on your front kicking your feet and pulling with your arms, alternating (taking turns) for 10 yds Hold on to this kick board and kick using up-down dolphin kick for 10 yards Swim on your front kicking your feet and pulling with your arms at the same time for 10 yards Swim the front crawl (freestyle) with rotary breathing for 15 yards Swim the back crawl (backstroke) for 15 yards Swim the elementary backstroke with a whip kick and glide for 15 yards Swim the breaststroke using pull, breathe, kick, glide for 15 yards Swim the sidestroke with alternating arms, scissors kick, and glide for 15 yards The testing occurred during regular class times on Tuesday and Thursday mornings over a three week period during the middle of a fall academic semester. The instructor of the swim classes who was also the assistant coach for the women’s varsity competitive swim team encouraged students to participate in our study and allowed them to come in pairs or threesomes to the shallow end (~ 1 yard (or 0.91m) depth) of the indoor 50 meter (54.7 yards) x 25 yard (22.86 m) University swimming pool while the remainder of the class participated in normal class activities in the middle and deep ends of the pool. The pool water temperatures were held constant at 26.7o C. Air temperature was a consistent 29.4o C. The shallow end of the large swimming pool was set up as three testing stations to which participants rotated in pairs or threesomes. Station one included breath holding, prone float, prone glide, supine float, and supine glide items. Station two tested combined stroke on the front using alternating arms, combined stroke on the front using simultaneous arms, dolphin kick with a kick board for 10 yards, plus front and back crawl strokes for 15 yards. At station three students were asked to perform the breaststroke, elementary backstroke, and side stroke, each for at least 15 yards. Test administrators asked each student to attempt each skill three times for purpose of establishing reliability. If students passed their first two attempts, the third attempt was omitted. Performance of the skills at each station were recorded by a video camcorder (either SONY or Panasonic models) affixed to a tripod that allowed the tester to pan the camera to follow participants as they moved. Each video camcorder recorded the swimming skills on a miniDV tape for later replay on a video recorder and large screen monitor. Video capture rate was 30 frames per second with the electronic shutter on the automatic setting. Student participants started at any of the three stations and rotated to the next open station. A set order of testing purposefully was not followed to ensure that no testing order affect occurred. If students became fatigued while performing any skill, they were permitted as much time as necessary to recover. If necessary, they were allowed to complete skills during the next class period two or five days later to eliminate the potential impact of fatigue on the results. Upon completion of the data collection, the investigators created a content analysis for each of the miniDV videotapes that served as an index to locate individual students. Both investigators then sampled approximately 10 trials of each skill item and independently observed and classified the performance as successful (pass) or unsuccessful (fail) according to the American Red Cross (2004) criteria (Table 1). We compared results and calculated the proportion of exact agreement to ensure that we were in agreement more than P = 0.80, or 80% exact agreement. When those levels of inter-rater objectivity were assured, the second investigator viewed all the trials for all 31 participants and classified them as either successful or unsuccessful. Subsequently, successful performances (on at least two out of three trials) were recorded in a spreadsheet as ones (1). Unsuccessful attempts (at least two of three trials that did not reach the criterion standard) were placed in the spreadsheet as zeros (0). results Guttman’s (1950) scalogram matrix orders both participants and test items according to the number of successful completions. In other words, the least successful (and presumably least skilled and experienced) participant was that individual who completed the fewest skill items. The most successful participant was the person who successfully performed the most items. Conversely, the easiest item was that which was completed by the most participants and the most difficult item was the one completed by the fewest participants. The swimming skill items passed most frequently by the current sample of college students were breath holding, combined stroke on the front with alternating arms, and front crawl which were passed by all participants. The swimming skill items that were passed least frequently (by only 81-84% of the participants) were the prone and supine glides, elementary backstroke, and sidestroke. Slightly more than half (16) of the participants successfully passed all items. Only one participant passed fewer than ten items (i.e., nine). On average, participants passed 12.2 of the 13 items. The overall coefficient of reproducibility for the order of items was CR = 0.93. dIscussIon The results of the scalogram analysis performed in the current study indicated that this selected set of thirteen swimming skill items could be quite reliably performed in the order proposed by the 2004 American Red Cross learn-to-swim program because of the relatively high coefficient of reproducibility in which CR = 0.93. This means that three second breath holding, front and back floating for five seconds, followed by a 10 yard combined stroke on the front using alternating arms are the least difficult swimming items that can be introduced first, at least to young adult swimmers. Front crawl stroke also can be introduced reasonably early in the learn-to-swim process for young adults. Other strokes appear to be more difficult, including the resting strokes of elementary backstroke and sidestroke. Described in developmental terms, these thirteen swimming items identified a reasonably robust inter-test developmental sequence. In Harrod’s (1990; Harrod & Langendorfer, 1991) previous scalogram study that tested some of these same items (albeit using 1981 Red Cross item descriptions) with elementary-aged children, the range of coefficients of reproducibility was CR = 0.64 to 0.81. At least for the young adult sample tested in the current study, no higher coefficient of reproducibility could be obtained by altering the proposed order. The primary difference between the results of the current study and those of Harrod (1990; Harrod & Langendorfer, 1991) was that the prone (front) and supine (back) floating items were indeed accomplished more successfully by the young adults than they were by the children. Harrod discovered that children appeared to more easily perform a front and back glide in which they could move their arms and
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average VO2 measured during resting
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Figure 2. Repeatability of the LTin
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Pahlen Norge AS Pahlen Norge AS Cha
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