Summary
The purpose of this study was to determine whether neural and/or muscular factors contributed to the inferior strength-related motor performances of obese adolescents. Subjects were 10 non-obese (14.6% fat) and 11 obese (32.3% fat) males matched for age (15–18 years), level of maturity (Tanner stages IV and V), lean body mass, and height. Peak torque (PT) was measured during maximal voluntary isometric (IS) and isokinetic (IK) knee extension (KE). Peak twitch torque (TT), time to peak torque (TPT), and half-relaxation time (HRT) of the knee extensors were elicited by percutaneous electrical stimulation. The interpolated twitch technique was used to determine the extent of motor unit activation (% MUA) during maximal voluntary IS KE. Knee extensor cross-sectional area (CSA) was determined by computed axial tomography taken at the mid-thigh. All strength and area measurements were made on the right side of the body. Obese subjects had significantly (P < 0.05) lower maximal voluntary IS and IK KE strength normalized for body weight, and significantly lower % MUA during IS KE. There were no significant differences (P > 0.05) between groups for absolute or normalized (for the product of muscle CSA and height) ISPT, IKPT, and TT, knee extensor CSA, or TPT and HRT. These results suggest that reduced MUA and a lower strength per mass ratio (due to excess fat) are probably important contributing factors to the poorer motor performances of the obese, especially for complex motor tasks involving large muscle groups and the support or moving of body weight.
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References
Bar-Or O (1983) Pediatric sports medicine for the practitioner: from physiologic principles to clinical applications. Springer, New York Berlin Heidelberg
Belanger AY, McComas AJ (1981) Extent of motor unit activation during effort. J Appl Physiol 51:1131–1135
Beunen G, Malina RM, Ostyn M, Rensen R, Simons J, VanGerven D (1983) Fatness, growth and motor fitness of Belgian boys 12 through 20 years of age. Hum Biol 55:599–613
Blimkie CJR (1989) Age- and sex-associated variation in strength during childhood: anthropometric, morphologic, neurologic, biomechanical, endocrinologic, genetic and physical activity correlates. In: Gisolfi C, Lamb D (eds) Perspectives in exercise science and sports medicine, vol II. Youth exercise and sport. Benchmark Press, Indianapolis, pp 99–163
Blimkie CJR, Ebbesen B, MacDougall D, Bar-Or O, Sale D (1989) Voluntary and electrically evoked strength characteristics of obese and non-obese pre-adolescent boys. Hum Biol 61:515–532
Bosco C, Rusko H, Hirvonen J (1986) The effect of extra-load conditioning on muscle performance in athletes. Med Sci Sports Exerc 18:415–419
Bullen BA, Reed RB, Mayer J (1964) Physical activity of obese and nonobese adolescent girls appraised by motion picture sampling. Am J Clin Nutr 14:211–223
Carpenter A (1941) An analysis of the relationship of the factors of velocity, strength, and dead weight to athletic performance. Res Q 12:34–39
Close RI (1972) Dynamic properties of mammalian skeletal muscle. Physiol Rev 52:129–197
Davies CTM (1985) Strength and mechanical properties of muscle in children and young adults. Scand J Sports Sci 7:11–15
Davies CTM, White MJ, Young K (1983) Muscle function in children. Eur J Appl Physiol 52:111–114
Durnin JVGA (1971) Physical activity by adolescents. Acta Paediatr [Suppl] 217:133–135
Durnin JVGA, Rahaman MM (1967) The assessment of the amount of fat in the human body from measurements of skinfold thickness. Br J Nutr 21:681–689
Gutezeit G (1976) Motor behavior in obese children. Pediatr Adolesc Endocrinol 1:187–191
Huttunen N-P, Knip M, Paavilainen T (1986) Physical activity and fitness in obese children. Int J Obes 10:519–525
Ikai M, Fukunaga T (1968) Calculation of muscle strength per unit-cross-sectional area of human muscle by means of ultrasonic measurement. Int Z Angew Physiol Einschl Arbeitsphysiol 26:26–32
Kireilis RW, Cureton TK (1947) The relationships of external fat to physical education activities and fitness tests. Res Q 18:123–134
Kitagawa K, Miyashita M (1978) Muscle strengths in relation to fat storage rate in young men. Eur J Appl Physiol 38:189–196
Lohman TG (1986) Applicability of body composition techniques and constants for children and youths. Exerc Sport Sci Rev 14:325–357
Mahoney MJ, Klykylo WN (1983) An overview of anorexia nervosa, bulimia and obesity in children and adolescents. J Am Child Psychol 22:99–107
Maughan RJ, Watson JS, Weir J (1983) Relationships between muscle strength and muscle cross-sectional area in male sprinters and endurance runners. Eur J Appl Physiol 50:309–318
Rehs HJ, Berndt I, Rutenfranz J (1973) Untersuchungen zur Frage der Leistungsfähigkeit Adiposer unter besonderer Berücksichtigung des Sportunterrichtes. Z Kinderheilkd 115:23–39
Riendeau RP, Welch BE, Crisp CE, Crowley LV, Griffin PE, Brockett JE (1958) Relationship of body fat to motor fitness test scores. Res Q 29:200–203
Ross WD, Marfell-Jones (1982) Kinanthropometry. In: MacDougall JD, Wenger HA, Green HJ (eds) Physiological testing of the elite athlete. Canadian Association of Sport Sciences, Mutual Press, Ottawa, pp 75–115
Sale DG, MacDougall JD, Alway SE, Sutton JR (1987) Voluntary strength and muscle characteristics in untrained men and women bodybuilders. J Appl Physiol 62:1786–1793
Sills FD, Everett PW (1953) The relationship of extreme somatotypes to performance in motor and strength tests. Res Q 24:223–228
Thoren C, Seliger V, Macek M, Vavra J, Rutenfranz J (1973) The influence of training on physical fitness in healthy children and children with chronic diseases. In: Linneweh F (ed) Current aspects of perinatology and physiology of children. Springer, Berlin Heidelberg New York, pp 83–112
Vandervoort AA, Quinlan J, McComas J (1983) Twitch potentiation after voluntary contraction. Exp Neurol 81:141–152
Wilkinson PW, Parkin JM, Pearlson G, Strong H, Sykes P (1977) Energy intake and physical activity in obese children. Br Med J 1:576
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Blimkie, C.J.R., Sale, D.G. & Bar-Or, O. Voluntary strength, evoked twitch contractile properties and motor unit activation of knee extensors in obese and non-obese adolescent males. Eur J Appl Physiol 61, 313–318 (1990). https://doi.org/10.1007/BF00357619
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DOI: https://doi.org/10.1007/BF00357619