Eur J Appl Physiol 43, 229-234 (1980) European Journal of

Applied Physiology and Occupational Physiology �9 Springer-Verlag 1980

Anaerobic Power Output of Young Obese Men: Comparison with Non-obese Men and the Role of Excess Fat

Kaoru Kitagawa ~, Masayasu Suzuki 2, and Mitsumasa Miyashita

Laboratory for Exercise Physiology and Biomechanics, Faculty of Education, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo t13, Japan

Summary. Anaerobic power output was measured by the staircase climb test in 14 obese, 16 lean, and 21 ordinary men aged from 18-22 years. Fat storage rate (%fat) was estimated by densitometry. The obese group ranked highest with an av- erage power output of 1,012 W. This value was significantly higher than those of the other two groups, 890 W for lean subjects and 855 W for ordinary subjects. The power output per kilogram of lean body mass of the obese group was the high- est also. However, the vertical velocity was the lowest although the difference among the three average values was not statistically significant. To investigate the effect of excess fat, eight non-obese subjects engaged in an added-weight ex- periment. The value obtained was almost the same as for the obese group. The ad- ded weights made the vertical velocity decrease but the power output increase. Consequently, it was obvious that the excess fat of an obese man played a role only as an inert mass in the power output measurement. A significantly higher power output of the obese group might be due to more excess fat, and obesity itself was an advantage in the staircase climb test.

Key words: Obesity - Anaerobic power output -- Added-weight experiment

Obesity tends to cause cardiac diseases directly and/or indirectly. Accordingly, so as to examine the respiratory-cardiovascular system of an obese person, aerobic power in maximal and submaximal oxygen uptakes has been measured in relation to body composition by many researchers. Observing maximal oxygen uptake for a given lean body mass (LBM), Buskirk and Taylor [4] and Welch et al. [ 13] showed no statistical difference between obese and non-obese groups and concluded that obesity had no ef- fect on the maximal performance of the respiratory-cardiovascular system. However,

1 Present address: Laboratory for Exercise Physiology and Biomechanics, School of Physical Educa- tion, Chukyo University, Kaizu-cho, Toyota, Aichi 470-03, Japan 2 Present address: Laboratory of Biomeehanieal and Physiological Performance, Nippon College of Health and Physical Education, 7-1-1 Fukasawa, Setagaya-ku, Tokyo 158, Japan Offprint requests to: Dr. K. Kitagawa (address see above)

0301-5548/80/0043/0229/$ 01.20

230 K. Kitagawa et al.

D e m p s e y et al. [7] and Davies et al. [6] presented the opposite conclus ion. The inf luence of obesi ty u p o n aerobic power is still conflicting. In addit ion, it is wel l -known

tha t an obese person is inferior in short and quick movemen t s where cardiac funct ion is

on ly slightly involved. F o r example, R i endeau et al. [11] showed lower scores in the s tanding b road j u m p , 75-yd dash and 220-yd dash compared with lean men. Musc le

s t rength per L B M of obese m e n was also lower t han that of non-obese m en as pointed ou t by our previous work [9]. Since a lmost all the energy of those m ovem en t s was re-

leased th rough anaerobic process, it is i mp o r t a n t to invest igate how obesi ty affects

anaerob ic power or anaerob ic power output . The purpose of this s tudy was to compare

the anaerob ic power ou tpu t of obese m e n with non-obese m e n and to examine the role

of excess fat o f obese me n in anaerob ic power ou tpu t by m eans of an "added-weight" experiment .

Methods

Subjects

Fifty-one men volunteered to participate in this study. All were university students, ages 18-22 years. On the basis of fat storage rate (% fat), they were grouped into "obese" (20% fat or more), "lean" (less than 10% fat), and "ordinary" (10-19.9% fat). The physical characteristics of the three groups are presented in Table 1. Behnke and Wilmore [ 1 ] postulated that the threshold of obesity is attained when fat storage con- stitutes about 20% of the body weight. Hence, their proposal for determining obesity was adopted for use in this study.

Anaerobic Power Output

To measure anaerobic power output, the staircase climb test of Margaria et al. [10] was employed. The subjects were asked to run up a staircase at top velocity two steps at a time. The height of each step was 17.5 era. Photoelectric cells were placed on the fourth and sixth steps and the time interval between interruptions in the fight beams was recorded with an electronic photosensitive device accurate to 0.001 s. Each subject performed the test five times. Discarding the best and worst times, the remaining three times were averaged to determine each subject's value. Anaerobic power output was calculated as follows and then converted into watts (W):

Anaerobic power output - body weight, including clothing (kg) x 0.175 (m) x 4

time (s)

To investigate any effect of "artificial obesity" on the anaerobic power output, eight non-obese subjects participated in an added-weight experiment. Two weights of 10.1 kg and 20.2 kg were used and attached by a belt around the waist of the subject. Each subject completed the test three times in the same manner as described above-once with no extra weight, once with 10.1 kg added, and finally with 20.2 kg of additional weight, The rest time between each test was approximately 15 rain.

Body Composition

Underwater-weighing method was used [9] and % fat was calculated according to the revised formula of BroSek et al. [3].

Anaerobic Power Output of Obese Men

Table 1. Physical characteristics of the subjects

231

n Height Weight % fat LBM Fat (cm) (kg) (%) (kg) (kg)

Obese a 14 170.7 _+ 5.6 74.68 _+ 9.82 24.8 + 1.9 56.14 _+ 7.05 (159.8 - 178.8) (58.32 - 91.67) (22.5 - 28.1) (41.93 - 68.39)

Lean 16 170.2_+ 3.6 60.17_+ 4.30 8.4_+ 1.2 55.15 + 4.14 ( 1 6 2 . 2 - 175.3) ( 5 1 . 0 2 - 66.90) (5.5-- 9.9) (45.97-- 61.37)

Ordinary 21 171.0 + 6.3 59.73 _+ 7.61 13.5 _+ 2.7 51.61 _+ 6.48 (159.9 - 181.7) (49.71 - 78.60) (10.0 - 18.3) (40.57 - 67.52)

18.54 + 3.16 (13.59 - 23.28)

5.02 _+ 0.74 ( 3 . 3 9 - 5.96)

8.12 _+ 2.01 ( 5 . 1 9 - 11.95)

"Obese: 20% fat or more; lean: less than 10% fat; ordinary: 10--19.9% fat Values are means _+ SD Figures in parentheses indicate the range

Table 2. Anaerobic power output and vertical velocity

Power Power/LBM Velocity (W) (W/kg) (m/s)

Obese 1,012 _+ 208 18.0 + 2.5 1.37 + 0.18 (716 - 1,389) (12.7 - 23.5) (0.97 - 1.73)

Lean 890_+ 123 16.1 _+ 1.6 1.49 + 0.18 ( 7 1 6 - 1,085) (13.2-- 18.7) ( 1 . 2 2 - 1.91)

Ordinary 855 _+ 116 16.6 _+ 1.2 1.44 _+ 0.11 ( 7 1 4 - 1,200) ( 1 4 . 2 - 18.7) (1.23 - 1.60)

F-value 4.96 a 4,48 ~ 2.07

" p < 0.05 Values are means _+ SD Figures in parentheses indicate the ranges

Results

As indicated in Table 2, the obese group ranked highest with an average power output of 1,012 W for anaerobic power output and 18.0 W/kg of LBM. The lean and the ordi- nary groups had similar values of 890 and 855 W for anaerobic power output and 16.1 and 16.6 W/kg of LBM, respectively. According to ANOVA, those averages of the obese group were statistically superior to the values obtained by the other two groups. But there were no significant differences between the two non-obese groups. On the oth- er hand, the mean vertical velocity of the obese group ranked lowest with 1.37 m / s .

Table 3 shows correlation coefficients between anaerobic power output and LBM. The simple correlation coefficients (r) are significantly below 1%. Keeping body weight statistically constant, the partial correlation coefficients (rm.3) resulted in no sig- nificances. This was caused by the body weight which had higher correlation coeffi-

232

r r12.3

K. Kitagawa et al.

Obese 0.711 a -0.205 Lean 0.701 a --0.088 Ordinary 0.808 b 0.125

Total 0.733 b 0.247

T a b l e 3, Correlation coefficients between anaerobic power output and LBM

ap < 0.01 bp < 0.001

r: simple correlation coefficient raz.3: partial correlation coefficient with body weight held constant

Table 4, Results of an added-weight experiment (n = 8)

a) Change in body dimensions

Height Weight % fat LBM Fat (cm) (kg) (%) (kg) (kg)

0 kg 169.6 _+ 5.5 61.83 + 5.69 8.6 +_ 1.9

+10.1 kg 7!.93 + 5.69 a 21.5 + 1.9 a

+20.2 kg 82.03 + 5.69 a 31.2 + 2.0 a

56.49 + 5.26 5.34 + 1.38

15.44 + 1.38 a

25.54 + 1.38 a

Values when artificial weights are regarded as fat Values are means _+ SD

b) Change of anaerobic power output and vertical velocity

Power Power/LBM Vertical velocity (w) (W/kg) (m/s)

0 kg 952 _+ 1637 (2.27)

/

+10.1 kg 1,000 + 15333 (3.08) (2,97)

|

+20.2 kg 1,04! _+ 1455

16.8 + 1.77 I 1.53 _+ 0.15~ [ (2.93) [ (2.73) [

177_+ (3 8) 141 _+ 015 (2.92) [ (4'49) I

_ J _ 0 . 1 4 ~ 18.4 + 2.0 j 1.29 +

t = 2.15 and t = 2.98 is required for significance at p < 0.05 and 0.01, respectively Values are means _+ SD Values in parentheses are t-values a by analysis of matched pairs

cients with LBM (r = 0.832--0.985) and with the anaerobic power output (r = 0.722--0.814), This was reasonable since the anaerobic power output was a product of the body weight which includes LBM and the vertical velocity.

Table 4 shows the results of the added-weight experiment. Regarding the artificial weights as fat, body composi t ion was changed (Table 4a). This allowed non-obese sub- jec ts to perform as obese. Analyz ing the effect of "artificial obesi ty" by analyses of matched pairs, it made the anaerobic power output increase significantly in spite of de- creasing the velocity (Table 4b). Addi t ional ly , it became clear that the heavier the weight, the higher the output and the lower the velocity for nearly all the values obtained.

Anaerobic Power Output of Obese Men 233

Discussion

The power output determined by the method used in this study was the product of body weight and the vertical velocity. In general, therefore, larger body weight and higher velocity have an advantage. The results obtained showed that the obese group over- came a disadvantage of lower velocity and produced higher power output than the lean and the ordinary groups. This result coincides with previous studies. Studying the anaerobic power output of male athletes through a similar procedure, Schreiber [12] showed that endomorphs had a higher value of approximately 200 kg �9 m/S (1960 W) than mesomorphs and ectomorphs. Davies [5] also measured the power output of young men averaging 71.33 kg in body weight and 30% fat. These values were very similar to those of the obese group in this study. It is shown herein that the obese group was superior in not only the absolute value of anaerobic power output but also the rela- tive value for a given LBM compared to the lean and the ordinary groups. LBM is con- sidered to be proportional to muscle mass [ 1, 4, 8] and may suggest a magnitude of anaerobic capacity, though not directly. Accordingly, it could be said that the higher re- lative value of the obese group resulted from the higher efficiency in utilizing anaerobic power. Concerning velocity, the obese group showed lower values than the non-obese groups, but the difference is not statistically significant.

The added-weight experiment was designed to make clear the role of excess fat of an obese subject on the power output and the vertical velocity. As body weight increased with the external weights, the output increased and the velocity decreased without any intrinsic change in the muscle. The values shown in Table 4 are almost the same as the obese group in Table 1. Thus, non-obese subjects became "artificially obese" in relation to the output and the velocity as well as in body composition. The role of excess fat of obese men was an extra inert mass in this type of exercise. Accordingly, obesity per se will increase the power output but decrease the velocity and will be more effective for relative output per a given LBM.

In conclusion, the obese men had a significantly higher anaerobic power output and were more effective in the staircase climb test than the non-obese men. This was due to the excess fat of the obese men acting as inert mass, and obesity itself was an advantage in the type of exercise used in this study.

References

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Accepted December 21, 1979