RELATIONSHIPS OF MECHANICAL POWER TO PERCEIVED EXERTION AND VARIOUS PHYSIOLOGICAL PARAMETERS MEASURED IN ELITE YOUTH DISTANCE RUNNERS AND CONTROLS

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1 RELATIONSHIPS OF MECHANICAL POWER TO PERCEIVED EXERTION AND VARIOUS PHYSIOLOGICAL PARAMETERS MEASURED IN ELITE YOUTH DISTANCE RUNNERS AND CONTROLS Egene W. Brown, Pal Vogel, Byeong Hwa Ahn and Sharon Evans In many stdies of hman movement, calclations of mechanical energy and physiological energy costs of exercise (Aleshinsky, 1986; Bhambhani & Singh, 1985; Cavagna, Thys & Zamboni, 1976; Robertson & Winter, 198; Pierrynowski, Winter & Norman, 198; Saito, Ohkwa, Ikegami & Miyamra, 1983; Sakrai & Miyashita, 1985; Williams & Cavanagh, 1983; Williams, 1985; Winter, Qanbry & Reimer, 1978; Zrrgh, 1981) have been sed as tools to describe and compare performance. The prpose of the present stdy was to expand pon these comparisons by drawing relations between mechanical power and ratings of perceived exertion as well as relations between mechanical power and physiological costs of exercise. Methods Sbjects The sbjects for this stdy were a sb-sample of participants in a longitdinal, interdisciplinary stdy of elite yong distance rnners (Seefeldt & Steig, 1986). Specifically, data sed in this stdy were cross sectional and were obtained from the forth year of data collection in the longitdinal stdy of elite yong distance rnners. Therefore, sbjects were familiar with their performance reqirements in the data collection process. In addition to the sb-sample of elite yong distance rnners, a sb-sample of control sbjects was selected from the poplation of sbjects sed in the longitdinal stdy. This reslted in an age and gender distribtion for this stdy of elite yong rnners and controls as shown in Table

2 Collection of Physiological and Psychological Data Dring each exercise bot, carbon dioxide prodced and oxygen ptake were measred sing the traditional Doglas bag method as described by Consolazio, Johnson, and Pecora (1963). Gas collections were fractionated into 1 minte bags. Heart rate was also monitored throghot the stress test. Heart rates were recorded for each sbject at the end of the first, second, and third minte of each exercise bot. At the start of each rest interval and at the end of the stress test, blood pressre, blood lactate, and ratings of perceived exertion (Borg & Noble, 1974) were measred. Blood pressre was measred with a sphygmomanometer. Blood lactate was measred by taking arterialized blood samples from the prewarmed finger tip and analyzed in a Roche 64 Analyzer. Cinematographic Data Collection Standard cinematographic procedres, sing a 16mm LOCAM camera, were employed to record the rnning pattern exhibited by the sbjects dring their stress test. Commencing at the middle ofthe third minte (15 seconds) into each complete exercise level, cinematographic records of 3 or more strides were obtained at 1 frames per second on each sbject. A Vangard Motion Analyzer was sed to project the processed film images onto a screen srface. For each level, a complete stride, beginning and ending with left heel strike, was digitized to obtain kinematic information essential for the calclation ofmechanical power. A model for the calclation of mechanical power dring distance rnning (Williams & Cavanagh, 1983) was sed and standardized by body mass (power/mass). According to Williams and Cavanagh, the model determines "the total cycle mechanical power adjsted for energy transfer, elastic storage and recovery of energy, the relative metabolic cost of negative and positive msclar work, and contribtions of nonmsclar sorces to negative power." In sing this model, coefficients a, b, c, and d were set to eqal.63,.35,.85, and 3, respectively. It shold be noted that if different coefficients were set for all of the sbjects, the calclated magnitdes of power standardized by sbject mass wold have changed. However, their correlations to the physiological and psychological parameters wold not differ. Reslts Table 3 is a smmary of the performance times Clevel and 487

3 Table 1. Age and gender distribtion of sbjects Boys Gids Entire Rnners Controls Rnners Controls Poplation N I 15 Average Age (mo.) Age Range (mo.) Stress Test A stress test was administered to each ofthe 15 sbjects chosen for this stdy. The stress test protocol consisted of alternating 3 mintes of rnning on a treadmiji and 3 mintes of rest. Between each exercise bot, the treadmill speed and grade were systematically increased as shown in Table 2. Sbjects, tested with this protocol, were asked to rn to exhastion. Table 2. Stress test protocol ExerciselRest Treadmill Treadmill Time Protocol (% Grade) Speed (mls) (min) Levell Exercise Level 2 Exercise Level 3 Exercise Level 4 Exercise Level 5 Exercise Rest Level 6 Exercise

4 minte) which were achieved by the male and female rnners and controls. It shold be noted that 8 of the 15 sbjects discontined their stress test at a time other than the end of a level. Table 3. Nmber of sbjects achieving designated performance times Performance Time Boys Girls Entire (IeveUminte) Rnner Control Rnner Control Poplation 411 I 1 2 4/ / / / /3 6/ /2 2 2 Figres 1 throgh 4 are reslts obtained for a male rnner. These patterns, however, are typical for all sbjects tested. It can beseen.that the vales for oxygen ptake (V 2 ) respirtory qotient (VCO/V2)' vanilatory eqivalent of oxygen ptake (VeN 2 ), and heart rate behave in an inclined, saw-toothed pattern. Dring rest, the magnitde ofthese parameters tends to decrease. Dring exercise, the magnitdes increase from one minte to the next. However, the magnitde of these parameters tend to increase from one level to the next. 488

5 1. --I' OQ 9. "" e U'<I, U'<I l.m\, ' "" """'. 1. Po_/IC,. S8f', " """. lnl, U'<\, U'<\, ><,.". ' -p- Figres 1 4. Reslts obtained for a male rnner. (Note that these reslts were typical of those fond in all sbjects.) 2 c,e i: :: w 'D. " '2 <l. ' 1," " a:. 5 '2 " 7!. ' -!. " e " U --' 4 2, 1 -c< Il. 1 9 e 4 J. PoI". lactvt. ll9{,, Lt'C1, U'<\ \,.", U><, > "c 4 O <:. J6 :: 32 ] 28 i:i to 24 E :.g 2 > I. -.: U, to ',.5 1, " 1. e O.SI..8 a:,7 o,e O. J<. " Il. 1O '.,a5 C E 17 ':>,.,, D -" 145 " a: 1:: :r I 12 I\ 1' " e' c 'E 4 ' 9. J.x. ' " '!! '2 7.:< " - : _, Il. 4 J 'oflle., Uplolo 8II'1J1ol. "" """, Ll'<1' U><" 1M\,""", C; I E os :: : 'D iii.!! Vl 19 le 17,,,., 'J' 12 <; J<? ". " Il.

6 Measres for lactate, ratings of perceived exertion, and blood pressre were taken immediately after each bot of exercise. The patterns tended to increase from one measre to the sbseqent measre. The vales of mechanical power calclated for a complete stride occrring dring the third minte of each level behaved in a similar manner to the vales obtained for lactate, ratings of perceived exertion, and blood pressre. In an attempt to establish relationships between mechanical power and the other physiological and psychological parameters, it was decided to only se data which was obtained either dring the third minte of exercise or at the start of a rest interval. Ths, for data sets were obtained for a sbject who achieved a performance time of the second minte ofthe fifth level. This approach reslted in for sbjects with three sets of data, eight sbjects with for sets of data and three sbjects with five sets of data. Sets of correlations were calclated for each sbject. These were averaged by sex and experimental grop and are reported in Table 4. From Table 4, it is evident that relatively high average correlations existed between mechanical power and all other parameters except for blood pressre. Table 4. Correlations of mechanical power with pllysiological allll psycllloglcai parameters Average Range Average Range Average Range Girls Enli R C RC Poplation EJI\i Boys Girls Poplation RC R C f'llire noys Poplation R C Oxygen Uptake Respiratory Qotient Venilalory Eqivalent Hearl Rale Laclale I'ercclved Exertion Blood Pressre

7 References Aleshinsky, S. Y. (1986). An energy 'sorces' and fractions' approach to the mechanical energy expenditre problem - 1. basic concepts, description of the model, analysis of a onelink system movement. Jornal ofbiomechanics, 19(4), Aleshinsky, S. Y. (1986). An energy 'sorces' and fractions' approach to the mechanical energy expenditre problem - I. movement ofthe mlti-link chain model. Jornal of Biomechanics, 19(4) Aleshinsky, S. Y. (1986). An energy 'sorces' and 'fractions' approach to the mechanical energy expenditre problem III. mechanical energy expenditre redction dring onelink motion. Jornal of Biomechanics, 19(4), Aleshinsky, S. Y. (1986). An energy 'sorces' and 'fractions' approach to the mechanical energy expenditre problem IV criticism ofthe concept of 'energy transfers within and between links'. _Jornal ofbiomechanics, 19(4) Aleshinsky, S. Y. (1986). An energy 'sorces' and 'fractions' approach to the mechanical energy expenditre problem - V. the mechanical energy expenditre redction dring motion ofthe mlti-link system. Jornal of Biomechanics, 19(4), Bhambhani, Y., & Singh, M. (1985). Metabolic and cinematographic analysis of walking and rnning in men and women. Medicine and Science in Sports and Exercise 17(1), Borg, G.A.V., & Noble, B. J. (1974). Perceived exertion. In J. Wilmore (Ed.), Exercise and Sport Science Reviews, 2 (pp ). Cavagna, G. A., Thys, H., & Zamboni, A. (1976). The sorces of external work in level walking and rnning. Jornal of Physiology, Consolazo, C. H., Johnson, R E., & Pecora, L. J. (1963). Physiological measrements of metabolic fnctions in man. New York: McGraw - Hill. Robertson, D. G., & Winter, D. A. (198). Mechanical energy generation, absorption and transfer amongst segments dring walking. Jornal ofbiomechanics, Pierrynowski, M. R, Winter, D. A., & Norman, R W. (198). 491

8 Transfers of mechanical energy within the total body and mechanical efficiency dring treadmill walking. Ergonomics, 23(2) Saito, M., Ohkwa, T., Ikegami, Y., & Miyamra, M. (1983). Comparison of sprint rnning in the trained and ntrained rnners with respect to chemical and mechanical energy. In H. Matsi, & K. Kobayashi (Eds.), Biomechanics, VIII - B (pp ). Sakrai, S., & Miyashita, M. (1985). Mechanical energy changes dring treadmill rnning. Medicine and Science in Sports and Exercise, 17(J) Seefeldt, V., & Steig, P. (1986). Introdction to an interdisciplinary assessment of competition on elite yong distance rnners. In M. r. Weiss, & D. Gold (Eds.), Sport for Children and Yoths (pp ). Williams, K R., & Cavanagh, P.R. (1983). A model for the calclation of mechanical power dring distance rwming. Jornal ofbiomechanics, 16 (2), Williams, K R. (1985). The relationship between mechanical and physiological energy estimates. Medicine and Science in Sports and Exercise, 17 (3) Winter, D. A, Qanbry, A., & Reimer, G. D. (1976). Analysis of instantaneos energy of normal gait. Jornal of Biomechanics, Winter, D.A, Qanbry, A., & Reimer, G. D. (1976). Instantaneos energy and power flow in normal hman gait. In P.V. Komi (Ed.), Biomechanics V-A (pp ). Zarrgh, M. Y. (1981). Power reqirements and mechanical efficiency of treadmill walking. Jornal ofbiomechanics, 14(3)