Performance of Young Male Swimmers in the 100-Meters Front Crawl

Pediatric Exercise Science, 2010, 22, 278-287 2010 Human Kinetics, Inc. Performance of Young Male Swimmers in the 100-Meters Front Crawl Fabrício de Mello Vitor and Maria Tereza Silveira Böhme University of São Paulo Youth swimming performance may be influenced by anthropometric, physiology and technical factors. The present paper examined the role of these factors in performance of 100m freestyle in swimmers 12 14 years of age (n = 24). Multiple regression analysis (forward method) was used to examine the variance of the 100 meters front crawl. Anaerobic power, swimming index and critical speed explained 88% (p <.05) of the variance in the average speed of 100 meters front crawl among young male pubertal swimmers. To conclude, performance of young swimmers in the 100 meters front crawl is determined predominantly by physiological factors and swimming technique. Performance in high level swimming has been depended by components like technique (stroke technique, coordination, starts and turns), physical conditioning (aerobic conditioning, anaerobic conditioning, flexibility and strength) and psychological conditioning (stress control, motivation) (19). Some studies in sports science literature have used different methodologies to investigate performance in young swimmers. Klika and Thorland (13) sought to discriminate faster and slower swimmers, while other researchers examined a combination of variables that best explained performance of young swimmers in short distance (1,9,11,23) and medium distance (12) events. In some studies, biological age was assessed by level of sexual maturation (12,23) and the skeletal age (9), while others were not taken into account gender (11) or competitive levels (11,23). Furthermore, researchers have based on different methodologies to measure aerobic and anaerobic conditioning, anthropometric components, swimming techniques and body composition. Although internal validity of the measures has been selected by some studies, they have not taken into consideration real situations like competitions or training (ecological validity). Based on the findings of previous studies (1,4,5,9,11 13,23,26), anthropometric measures, general and specific physical conditioning, swimming technique, competitive level and maturational aspects should be analyzed in young swimmers performance. In comparison with high-level swimming, young swimmers studies have not showed any relevance in regarding to psychological aspects of performance. Vitor and Böhme are with Physical Education and Sports School Research Group of Youth Sports and Training, University of São Paulo, Brazil. 278

Performance of Young Male Swimmers 279 Therefore, the main hypothesis of the current study was that 100m front crawl in young male swimmers should be dependent on anthropometric, physical conditioning and swimming technique factors. Several determinants of young swimming performance may be associated with outcomes and processes of growth and maturation. Moreover, there are not studies investigating the performance of young Brazilian swimmers. Specifically, the aims of the current study were: 1. To assess the relationship among anthropometric variables, specific physical conditioning, swimming techniques and performance of young swimmers in the 100 m distance front crawl swimming; 2. To determine a combination among anthropometric variables, specific physical conditioning and swimming techniques that improves prediction of 100 m distance front crawl swimming. Subjects Materials and Methods Twenty-four male swimmers participated in this investigation after giving informed consent in accordance with the guidelines outlined by Ethics Committee of Physical Education and Sport School at São Paulo University (Protocol No. 2008/09). Swimmers competed at the state (São Paulo, SP) and national levels (Brazil) in 2007. All swimmers were classified as pubescent in agreement with Tanner stages (27). Subjects had trained for 3 to 4 years and 15 hr per week for at least the last two years. During the testing period (i.e., April), the weekly training volume was around twenty kilometers and training was performed mainly at aerobic pace and technique drills. The swimmers were in a ninth week of base period of training. Study Design The measurements were undertaken over 2 days: on Day 1, anthropometric measures, self-assessment of sexual maturation, anaerobic power test, performance in 100 m front crawl swimming, swimming technique, and chronological age while the critical speed test (CS) was taken on Day 2. Anthropometric Measures, Sexual Maturation and Chronological Age Anthropometric measurements were taken before beginning of training and are described as follow: height, was measured by Kawe tape measure to the nearest 0.1 cm fixed to the smooth wall and an object to identify the scope of the maximum size (e.g., ruler or clipboard); body mass, was measured by a digital scale to the nearest 0.10 kg (Techline, Model BAL-180,BR); arm span, was measured by a Eccofer tape measure with 3 m in length to the nearest 0.1 cm fixed at smooth surface and an object to identify the scope of the maximum distance between dactylion points (e.g., ruler or clipboard); hand length (was taken by the distance

280 Vitor and Böhme from styloid process of radius (located at the wrist) and dactiloid process (tip of middle finger), biacromial breadth (was taken by the distance from lateral edge of acromion process), biiliac breadth (was taken by the distance from lateral edge of iliac crest) were measured by a sliding caliper to the nearest 0.1cm (Sanny, American Medical from Brazil, BR); skinfolds (triceps and subscapular), were measured by a skinfold caliper to the nearest 0.1 mm (Sanny, American Medical from Brazil, BR) (14); hand width (was taken by the distance from first and fifth metacarpal of the hand) and foot width (was taken by the distance from first and fifth metatarsus of the foot) were measured by a sliding caliper to the nearest 0.1cm (Sanny, American Medical from Brazil, BR) (18), and finally, foot length (was taken by the distance from most posterior point of the heel to the tip of the most anterior projecting toe) was measured by a sliding caliper to the nearest 0.1cm (Sanny, American Medical from Brazil, BR) (4,18). Body fat measurement was according to the methods of Slaughter et al. (24). From the arm span and height measures, was calculated the Arm Span/Height Index, and from the biacromial and biiliac breadth measures, was calculated the Biacromial/Biiliac Index (18). The self-assessment of sexual maturation was analyzed by drawings of representative stages for sexual pilosity from one to five (stage 1 means biological immaturity while stage 5 means biological maturity) according Tanner stages (27). Chronological age was obtained by birth date. Swimming Performance All tests were performed in a 50 m pool (long course). Water temperature was kept between 25 and 28 degrees, as determined by FINA (Fédération Internationale de Natation). A stopwatch (Technos, YP2151/8P, BR) with precision of one hundredth of a second was used. The front crawl swimming was performed according to the regulations of FINA. Anaerobic Power Test (15) Anaerobic power test was performed by eight front crawl repetitions in a maximum effort, over a 25 m distance (8 25m front crawl), with three minutes of passive rest among repetitions. Subjects began the swim in the water and researchers started the timing manually when swimmers feet left the wall of the pool and times were finished when any hand was achieving the distance of 25 m. After eight repetitions, the average time was calculated and converted into average speed (m/sec) representative of each subject s performance. Athletes were not wearing bathing costumes that could offer potential hydrodynamic advantages. The warm-up session in the pool lasted around twenty minutes and was composed of technical and low intensity aerobic exercises Performance in the 100 Meter Front-Crawl Performance in the 100 m front crawl was measured in a maximum effort and start was given when the swimmers were in the water. This performance occurred after forty minutes of active recovery after the anaerobic power test with purpose of regenerate metabolic system. According to literature (16), after forty minutes

Performance of Young Male Swimmers 281 of moderate continuous exercise, high lactate concentration obtained after a high intensity effort decrease at rest levels. During the forty minutes, swimmers performed technical exercises as well as moderate intensity aerobic exercises to allow recovery from their mental and physical tiredness. Times were recorded in seconds, afterward, average speeds were calculated. This performance measure was the same one (100 m front crawl) used to measure the swimming techniques as follow: Stroke Rate, Distance Per Stroke, Swimming Index (25) The stroke rate was determined from the elapsed time for three arm cycles between 15m and 45meters of the 100 m sprint swim. That distance considered to eliminate the effects of starting from the wall and of turning. The timing was started when the right hand of the swimmer was entered the water and was stopped when the right hand of the swimmer was entered the water for the fourth time, completing three arm cycles. The values for distance per stroke and stroke index were extracted from the measure of stroke rate, where: (a) Distance per stroke (m/cycle) = 100m swimming speed (m/s) divided by stroke rate (cycles/s). Although this method overestimates distance per stroke by 4-5% due to the push off from the side of the pool (25) because these results did not taken into account the dive start or any variation in mid-pool swimming speed and turning times, this is a systematic error which does not significantly influence subsequent comparisons between swimmers (7). (b) Swimming Index was calculated by multiplying the swimming speed (m/s) by distance per stroke (m/cycle). This index assumes that, at a given speed, the swimmer who moves the greatest distance per stroke has the most efficient swimming technique (25). Critical Speed Test (CS) (8). A greater velocity that can be maintained continually without fatigue defines Critical Velocity (17). The amount of work performed at the expense of the complete utilization of anaerobic stores and the mechanical power sustainable at the expense of the maximal O 2 consumption of the muscle group in question underlying the critical power definition (17). Based on them, di Prampero (22) states that critical velocity must be calculated with exhaustive times that are situated between two and twenty minutes. Others studies have supported the critical speed evaluation method by two distances in swimming (23) The test was performed by one repetition of 200 m front crawl and one repetition of 800 m front crawl at maximum speed intensity with interval of forty minutes between repetitions with purpose of regenerate metabolic system (16). The times were recorded in seconds and after that, were converted in speed (m/sec). The warm-up session in the pool lasted approximately twenty minutes supervised by their coach and was composed of technical and moderate intensity aerobic exercises. Forty minutes of active rest between 200m and 800m was done with aerobic exercises of low intensity. The critical speed was obtained through a regression slope between the distance and the time.

282 Vitor and Böhme Statistical Analysis The average speed during the 100 m front crawl swim was considered as dependent variable and all other variables were considered independent variables. Pearson s correlation coefficients were used to evaluate relationships between the variables. Multiple regression analysis (forward method) was used to verify the combination of significant independent variables that could predict the dependent variable (the average speed of the 100 m front crawl). A p-value of 0.01 was used to select variables to be included in the multiple regression models, and a p-value of 0.05 was used to evaluate the fit of multiple regression models. Statistical analyses were conducted using SPSS 13.0 (Chicago, IL). Results With regard to sexual maturation, among all twenty-four subjects, seven subjects were classified as stage three of pilosity while seventeen subjects were classified as stage four of pilosity, by then, all subjects engaged on pubescent stage as purposed by Tanner (1962). The chronological age was 13.0 ± 0.7 years. The descriptive values of the subjects are displayed in Table 1. Anaerobic power (r 2 =.67), swimming index (r 2 =.62), body mass (r 2 =.35), critical speed (r 2 =.34), biacromial breadth (r 2 =.32), chronological age (r 2 =.28) and height (r 2 =.28) were significantly correlated positively with the average speed of 100 m front crawl (p <.01; Table 2). Moreover, distance per stroke (r 2 =.28) was associated too with 100m front crawl at p <.05 (Table 2). To explore a model that gives the best prediction of performance, all the assumptions were tested (10) and the prediction model obtained is presented in Table 3. This procedure was only followed where an adequate number of observations existed. The normal distribution of residuals was checked and the model obtained was statistically significant (p <.05). Results indicated that prediction model explained 88% of variability of timing in 100 m front crawl performance in agreement with adjusted coefficient (Table 3). Anaerobic power had greater influence in observed model as showed by beta standard coefficient (0.49). Discussion Present data showed a significant relationship between 100m front crawl in eight (anaerobic power, swimming index, body mass, critical speed, biacromial breadth, chronological age and height) of twenty variables measured (Table 1). Furthermore, correlations showed that two variables were associated with physical conditioning (anaerobic power, critical speed), one variable was associated with swimming technique (swimming index), three variables were associated with anthropometry (body mass, biacromial breadth, height). These results are in agreement with the literature (9,11,12,23). The main finding of this study was that anaerobic power, swimming index, critical speed are the only variables that best explained (88%) 100 m front crawl performance in young swimmers with 13.0 ± 0.7 years. In other words, physical conditioning and technique seems like be more determinant than anthropometric

Table 1 Mean ± SD, Minimum and Maximum Values of Anthropometric Variables, Physical Conditioning and Stroke Parameters of Young Male Swimmers Variables Mean Standard Deviation Minimum Maximum Chronological Age (years) 13.0 0.7 12.0 14.0 Anthropometry Body mass (kg) 52.3 8.4 39.1 68.2 Height (cm) 163.5 6.3 152.0 175.0 Arm Span (cm) 169.0 8.4 156.0 184.0 Hand length (cm) 18.1 0.9 16.7 19.9 Hand width (cm) 10.1 0.7 9.1 12.0 Foot length (cm) 25.3 1.2 23.2 27.7 Foot width (cm) 9.7 0.5 8.7 10.9 Biacromial breadth (cm) 37.2 1.9 34.2 40.5 Biiliac breadth(cm) 25.9 1.4 23.3 28.0 Calculated Index Arm span/height index 1.0 0.0 1.0 1.1 Biacromial/Biiliac index 1.4 0.1 1.3 1.5 Body composition Triciptal skinfold(mm) 8.4 2.4 5.3 13.8 Subescapular skinfold (mm) 8.4 2.9 4.9 16.0 Body fat (%) 20.4 4.8 13.4 31.8 Specific Physical Conditioning Anaerobic Power (m / s) 1.65 0.08 1.52 1.83 Critical Speed (m / s) 1.15 0.07 1.02 1.30 Stroke Parameters Stroke rate (cycles/s) 0.79 0.06 0.68 0.92 Distance per stroke (m/cycle) 1.85 0.17 1.56 2.08 Swimming Index (m 2 /cycle/s) 2.71 0.34 2.09 3.24 Dependent Variable 100 meters front-crawl average speed (m/s) 1.46 0.07 1.31 1.58 283

284 Vitor and Böhme Table 2 Correlation Coefficients (r) and r 2 Values of Variables Associated with the 100-Meters Variables R r 2 Anaerobic power 0.82** 0.67 Swimming index 0.79** 0.62 Body mass 0.59** 0.35 Critical speed 0.58** 0.34 Biacromial breadth 0.57** 0.32 Chronological age 0.53** 0.28 Height 0.53** 0.28 Distance per stroke 0.53* 0.28 Biiliac breadth 0.50 0.25 Hand width 0.33 0.11 Arm span 0.32 0.10 Arm span/height index 0.24 0.06 Subscapular median 0.23 0.05 Foot length 0.21 0.04 Foot width 0.21 0.04 Hand length 0.18 0.03 Body fat 0.13 0.02 Triceps median 0.05 0.00 Biacromial/Biiliac index 0.03 0.00 Stroke rate 0.03 0.00 * p <.05; ** p <.01 Table 3 Multiple Linear Regression Model for Performance in the 100-Meters Front Crawl Race Among Young Male Swimmers N = 24 Beta Standard Coefficient Linear B Model Coefficient Significance Level Colinearity Tolerance R =.95 Intercept 0.11 0.41 R 2 =.90 Anaerobic Power 0.49 0.45 0.00* 0.62 1.59 average speed R 2 aj.=0.88 Swimming Index 0.39 0.08 0.00* 0.61 1.61 S.E= 0.03 Critical speed 0.31 0.31 0.00* 0.88 1.12 *p <.05 VIF

Performance of Young Male Swimmers 285 measures in this specific case. On the other side, anthropometry did not have any variable that could explain 100m front crawl performance in prediction model. The finding of a greater significant contribution of anaerobic power in 100 m swimming performance in the current study may be explained by energy expenditure along the race. Taking into account that subjects in the current study had an average time of 68.5 s (Table 1) in 100m front crawl, the metabolic point-of-view suggests that efforts rounded by 60 s has 70% of anaerobic contribution in performance (16). Moreover, Capelli, Pendergast and Termin (2) analyzed the metabolic contribution in 100 yards (91.4 m) with male swimmers (18.9 ± 0.9 years) and found that anaerobic contribution response for 66.8% of performance. This results showed that swimming performance of 100m distance is depended more of anaerobic metabolism than aerobic metabolism. Some studies have investigated anaerobic performance in young swimmers (9,11,23), but all of them was done with tests in land, however, other studies have analyzed anaerobic performance in a pool (13), but none of them measured anaerobic performance exactly like in current study. Nonetheless, no matter how was measured, anaerobic performance have showed be relevant to performance in short races (50 and 100 m) for young swimmers (9,11). Furthermore, anaerobic power in current study was strongly correlated with body mass (r =.62, p <.01), height (r =.55, p <.01), hand width (r =.57, p <.01) and biacromial breadth (r =.67, p <.01). Despite the fact anthropometric measures not entered in prediction model, they are fundamental to understand anaerobic performance. Except body mass, all other measures are determinate genetically (18) in agreement with literature, which states that genetics contribute around 50% of variance in short-term anaerobic performance (28). Swimming index was also significant to predicted model in present study corroborating with others studies in literature (11, 12, 13, 23; Table 3). Strazla, Tyka and Krezalek (26) found a medium value of 3.09 m 2 /cycle/s in young swimmers (14.7 ± 0.5 years) when performed 100 front crawl compared with a 2.71 m 2 /cycle/s of current subjects (13.0 ± 0.7 years). A short explanation to this fact may be due to difference in chronological age. Pelayo et al. (20) analyzed scholar swimmers between eleven to seventeen years-old and found that chronological age was together with arm span, the only swimming index predictors of best results when compared younger with older swimmers. Besides that, chronological age was statistically significant with 100 front crawl in current study (r =.53 p <.01) corroborating with Pelayo et al. (20). Based on literature (3), these results suggests that during learning, improvement is achieved mainly by attaining longer strokes as result of better orientation of motor surfaces (the surfaces of swimmer s arms and legs that generate a propulsive force) and increase in the span of the motor paths (distance covered by motor surfaces). Moreover, faster swimmers have better swimming index and consequently better technique in agreement with former and recent studies (6,25). Critical speed analyzed in present study was the third best variable that explained significantly the variance in 100 front crawl (Table 3). Other studies have showed aerobic performance as predictor of results for young swimmers (12). According Platonov (21), the 100 m front crawl race can be considered in terms of energy efficiency, with 55% contribution from anaerobic metabolism

286 Vitor and Böhme and 45% from aerobic metabolism, and it can be classified as a mixed race, because the aerobic energy source is also important to ensure endurance during the swim. This is consistent with the study by Capelli, Pendergast and Termin (2). These data confirm the significance of both anaerobic power and critical speed (an indicator of aerobic capacity) for predicting performance in the 100 m front crawl. According with studies that sought examine the combination of variables to explain 100m front crawl performance in young male swimmers, Geladas, Nassis and Pavlicevic (9) found 59% of the variance in the performance explained by the combination of the total upper extremity length, horizontal jump and grip strength in athletes between 12 14 years-old. Klika and Thorland (13) observed that both distance per stroke and muscularity index (lean body mass/stature 2 ) had significant influence (p <.05) on the performance of faster swimmers between 9 12 years-old. Based on these results, it became difficult has an idea about what is right because methodologies used by researchers are very different. In spite of this fact, almost all studies discussed at current study included variables related with anaerobic performance, swimming technique and aerobic performance as significant to explain 100m swim performance in young swimmers. Limitations of Study In the current work was not included any psychological indicators that might have influence in the environment of training. In addition, technical swimming parameters were not evaluated by a video camera. Conclusion In summary, anaerobic power test, swimming index and critical speed test explained 88% of the variability of the average speed for the 100 m front crawl swim. The absence of anthropometric variables in the regression model suggests that the performance of young swimmers in the 100 m front crawl is determined predominantly by physiological factors and swimming technique. References 1. Blanksby, B.A., J. Bloomfield, M. Ponchard, and T.R. Ackland. The relationship between anatomical characteristics and swimming performance in state age-group championship competitors. J. Swim. Res. 2:30 36, 1986. 2. Capelli, C., D.R. Pendergast, and B. Termim. Energetics of swimming at maximal speeds in humans. Eur. J. Appl. Physiol. 78:385 393, 1998. 3. Cardelli, C., D. Chollet, and R. Lerda. Analysis of the 100 m front crawl as a function of skill level in non-expert swimmers. J Hum Mov Stud. 36:51 74, 1999. 4. Carter, J.E.L., and T.R. Ackland. Kinanthropometry in aquatic sports: a study of world class athletes. Champaign, IL: Human Kinetics, 1994. 5. Chatard, J.C., C. Collomp, E. Maglischo, and C. Maglischo. Swimming skill and stroking characteristics of front crawl swimmers. Int. J. Sports Med. 11:156 161, 1990. 6. Costill, D.L., E. Maglischo, and A.B. Richardson. Handbook of sports medicine and science: swimming. Oxford: Blackwell Science, 1992.

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