Asia Pacific J of Clin Nutr. (1995) 4, Suppl 1, 29-33

Benefits of physical activity on nutrition and health status: studies in China

Chen Ji-Di, MD

Research Division of Sports Nutrition and Biochemistry, Institute of Sports Medicine, Beijing Medical University, Beijing, China.

---

The significance of physical activity for fitness is that it may change risk factors for chronic disease and improve functional and psychological status. Rational nutrition and scientific training are prerequisites for safe and useful exercise. Even mild iron deficiency anemia can affect physical capacity. Intensive exercise has been found to increase serum and erythrocyte lipid peroxide levels. Moderate exercise decreases the blood lipid peroxides and increases free radical elimination enzyme (SOD, GSH-Px, CAT) activities. Elite athletes have significantly lower Malonic dialdehyde (MDA) levels and higher SOD and GSH-Px activities. Zinc deficiency not only leads to an increase in free radical generation and lipid peroxidation and a depression of SOD activity, but also is harmful to immune function. Exercise can exacerbate the damage induced by iron deficiency or zinc deficiency. Long term diet restriction by gymnasts to control weight showed detrimental effects including growth retardation, menstrual disturbances, malnutrition, mental stress and muscle weakness. Comprehensive nutrition promotes growth rate and corrects malnutrition without a body fat increase in athletes. Exercise benefits the growth and development of bone and muscle and enhances muscle strength. The prevention of obesity is particularly important during periods of rapid growth. The establishment of an exercise life style during childhood will favor the best health.

---

Introduction

The importance of exercise for fitness is becoming clearer every day and it is a popular topic of conversation. People generally have a surface knowledge of the following:

1. Exercise may lower some risk factors for chronic diseases. Physical demands at work, at home and in transit have been dramatically reduced by modernization. People are leading a more and more sedentary lifestyle that leads to a progressive increase of such chronic diseases as obesity, coronary heart disease, diabetes, osteoporosis, and back pain. Exercise combined with a proper diet lowers certain risk factors for chronic disease. Thus it has important implications for health and is worth recommendation^1-4.

2. Exercise improves human functional status and metabolism. The oxygen uptake (V0₂), maximal oxygen uptake (V0₂ max), cardiac output (CO), and stroke volume increased significantly after running training⁵. Heart rate recovered faster after a 30 meter run at full speed in exercise trained children than non-trained controls⁶. Microcirculation, heart function, and lipid profiles improved in aged peopl 1000 e that jog or practice Qi-gong or Tai-chi as compared to control subjects^4,7-10.

3. Exercise improves psychological state and capacity to cope with stress. Regular exercise yields physical fitness, good mood, and well being across all ages and both sexes. The findings are supported by psychological, physiological, including neuromuscular, evidence¹¹. Quality of life scores improved significantly with condition training. With prolonged exercise training, runners seem to become more self-sufficient and more relaxed than before running. Jasnoske and Holmes have observed significant correlation between aerobic capacity and greater self-assurance and reduced tension¹¹. However, overexercising and repetitive competition can have harmful physical (staleness), psychological (tension, anxiety, and depression), and social (isolation) consequences¹². The interaction of many factors--expectation, distraction, self-motivation, social interaction and therapeutic attention-- has been suggested to be the cause of the beneficial effects of exercise on psychological status. Physiological effects include improved cardiovascular fitness, increased cortical cerebral blood flow and hemispheric synchronization, and reduced resting muscle action potential. Biochemical changes include increased peripheral and central catecholamine levels and activation of the opioid-hypothalmic-pituitary-adrenal axis with co-release of beta-endorphins^13,14.

Rational nutrition is a prerequisite for exercise. The famous saying, Life is an exercise" illustrates the importance of exercise. However, the best effects of exercise on health are achieved with scientific guidance for training with rational nutrition. For example, iron deficiency is the main cause of anemia in Chinese children and adolescent athletes15. Iron deficiency anemia (IDA), even in a mild form affects physical work capacity and work efficiency16,17. In turn, exercise affects iron absorption18 (Table 1). The proportion of dietary heme iron of Chinese athletes is low. The loss of iron through sweat in athletes cannot be neglected19. A study of the affects of IDA on erythrocytes showed that the damage was more serious in exercised rats with IDA. Loss of the band 3 protein of erythrocyte (RBC) membrane and the significant decrease of RBC deform-ability index percentages in the exercised rats with IDA implicated RBC membrane skeleton damage and a shortening of RBC life span20 (Fig 1).

Table 1. Effects of exercise training on iron absorption rate of child soccer players Indices Training period Non-training period Dietary 58Fe intake during expt'l period (m g) 221 ± 40 226 ± 42 Oral intake of 58Fe (m g) 923 ± 0 923 ± 0 Total amount of 58Fe intake (m g) 1144 ± 40 1148 ± 42 Output of fecal 58Fe (m g) 1056 ± 56 1012 ± 68 Iron absorption rate (%) 9.1 ± 2.9* l 1 .9 ± 4.7 (Adapted from Huo Zhou Ping and Chen Ji Di et al18) *Data compared to non-training period showed significance, P< 0.05

Figure 1. Effects of iron deficiency on RBC Dimax% of sedentary and exercise rats20

Data not sharing a common letter on top of the columns differ significantly. S-sedentary; E- exercise; NI- normal iron feed (iron content: 44ppm); ID- iron deficiency feed (iron content: 4ppm); MID- mild iron deficiency feed (iron content: 14ppm)

These results have provided evidence for the impor 1000 tance of iron nutrition for athletes. Intense exercise, with or without stress, was found to increase serum lipid peroxide levels. Lipid peroxides accumulated in the body are a direct cause of many diseases including age-related disease and even aging itself. RBC malonic dealdehyde (MDA) increased significantly after a bout of acute aerobic exercise (cycling at heart rate 170/min on a Monark Ergometer for 60 min)21 (Table 2). If the activities of free radical elimination enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) increase concurrently, the appropriate defensive system is working during exercise. Moderate exercise, especially after physical load has been adapted, has been found to decrease blood MDA levels and increase the free radical elimination enzyme activities21-22. RBC MDA levels were significantly lower and SOD and GSH-PX activities were significantly higher in elite athletes from the national training team than in those from university because nutritional and training status were both much better in elite athletes (Table 3).

Table 2. Changes of RBC MDA levels, RBC SOD and GSH-Px activity of athletes after a bout of aerobic exercise   RBC MDA (nMol/gHb) RBC SOD (m g/gHb) RBC GSH-Px (m /gHb) Pre-exercise 21.5± 0.9 399.3± 12.0 687.5± 20.3 Post-exercise 31.4± 1.3* 397.2± 13.6 859.5± 26.9** (Adapted fr 1000 om Cao Guo Hua and Chen Ji Di21) *Data compared with pre-exercise, P< 0.05 **Data compared with pre-exercise, P< 0.01

Table 3. Comparison of MDA levels and SOD and GSH-Px activity between elite athletes and student athletes   Elite athletes (n=30) Student athletes (n=12) Plasma MDA (nMol/ml) 1.58 ± 0.04 1.87 ± 0.25 RBC MDA (nMol/gHb) 16.26 ± 1.12 21.21± 0.87** RBC SOD (m g/gHb) 500 ± 20 408 ± 11* RBC GSH-Px (m g/gHb) 873 ± l0.6 657 ± 18.8** **Data compared with elite athletes, P< 0.001 * P< 0.05 (Adapted from Cao Guo Hua and Chen Ji Di23) It was also found that RBC SOD activity was significantly correlated with RBC zinc levels (r = 0.495, P < 0.05)23. Zinc deficiency leads to an increase of free radical ge 1000 neration, lipid peroxidation, and a depressed hepatic CuZn-SOD activity in both sedentary and exercised mice. Exercise strengthened the free radical elimination but zinc deficiency abolished the exercise induced adaptation24 (Table 4,5). Study of the effect of exercise and zinc deficiency on murine immune function showed that zinc deficiency and food restriction are both harmful to T-cell function. There is a decrease in splenic mononuclear cell (MNC) number, and a reduction in proliferation response of splenic cell to Con A and of IL-2 secretion25 (Table 6). Exercise exacerbated the damage caused by zinc deficiency and food restriction. Zinc repletion only partially repaired the damage of immune function induced by zinc deficiency. A three year follow-up study of a group of female gymnasts on long term weight control diets showed detrimental effects including growth retardation, menstrual disturbances, malnutrition, mental stress, and muscular weakness. The weight and height of the gymnasts were much smaller and shorter respectively than similarly aged urban girls. This effect may reflect both diet and selection of gymnasts. The menarche was delayed by one to two years, the average age for the observed gymnasts to have their first menstruation was 15.6 ± 1.58 years. It was 17.8 ± 0.57 years for those who had developed secondary amenorrhea and took medicines for the retarded menstruation. Energy, protein and minerals were in negative balance. Diet improvements for female gymnasts included an increase of calories to > 90% of the recommendation and protein intake to 1.9g/ kg of weight. Increased vegetable, fruit, and milk product intakes to ensure adequate of mineral and vitamin status were encouraged. There were improvements in growth and development, nutrient balance, and mental stress, with no increase of body fat. Weight reduction should be discouraged if athletes train normally and their body fat does not increase or is under 10% of their total weight26,27.

Table 4. Effects of zinc deficiency on MDA levels of liver tissue of mice (n= 8)     cytoplasm (nMol/mg prot) mitochondria (nMol/mg prot) Zinc deficiency Non-exerc 0.184± 0.017a 0.174± 0.007a   Exerc 0.171± 0.014a 0.205± 0.013b Pair fed Non-exerc 0.093± 0.005b 0.111+ 0.006c   Exerc 0.123± 0.007c 0.171± 0.010ad Normal control Non-exerc 0.120± 0.008c 0.145± 0.011d   Exerc 0.121± 0.007c 0.148± 0.006d Data sharing a common letter at the upper right does not differ significantly, P> 0.05 (Data adapted from Cao Guo Hua and Chen Ji Di31) Table 5. Effects of zinc deficiency on SOD activity of mice     Blood (m /ml ) Liver cyto-plasm (m /mg prot ) Liver mito-chondria (m /mg prot ) Zinc deficient non-exerc 480± 15.1a 84.9± 2.3a 21.9± 1.6a   exerc 513± 19.8ab 86.6± 3.1ab 24.9± 1.2ab Pair fed non-exerc 508± 21.7ab 91.3± 2.4bc 23.7± 0.9a   exerc 551± 11.6bc 98.5± 5.1c 28.7± 1.8b normal control non-exerc 527± 14.3b 95.9± 2.4c 22.1± 0.9a   exerc 593± 20.0c 119.2± 3.9c 27.6± 1.5b (Adapted from Cao Guo Hua and Chen Ji Di24) No significant differences were seen if the data share a common letter at the upper right, P>0.05 n=8 Table 6. Effects of zinc deficiency and exercise on murine splenic lymphocytes (X± SD)   MNCx106 spleen Con A (cpm) IL-2 (cu/ml) n 9 8 6 ZD T 6.08± 1.85a 3867 ± 231a 3.27 ± 0.65a   S 8.66± 2.75a 5353± l967a 4.08± l.86ab PF 1000 T 16.02± 7.67ab 6294± l836b 5.32± 3.48b   S 22.06± l2.79b 15469± 5228c 15.15± 5.81c AL T 35.9± l8.84c 18275± 5195c 32.93± 11.18 d   S 43.77 ± l4.17c 19472± l967c 23.97e± l0.82 ZD: zinc deficien 1000 cy; PF: pair fed; AL: ad libitum T: exercise group; S: sedentary group. Data without a same letter differ significantly, P< 0.05 (Adapted from Feng Jian Ying and Chen Ji Di25)

Figure 2. Comparison of body fat between elite and non-elite athletes26

Data not sharing a common letter on the top of the columns differ significantly EA: elite athletes from national team; NEA in N: non-elite athletes in Northern parts; NEA in S: non-elite athletes in Southern parts

Exercise should begin in childhood.

Adequate exercise training with proper nutrition, started during childhood, will produce the best health benefits. Differences in diet, exercise, and health may affect the growth and development stages to a certain extent. Exercise is important for skeletal development²⁸. Physical exercise probably induces bone mass increment by stimulating osteogenic cells by a piezoelectric mechanism. A sedentary lifestyle will induce bone mineral absorption due to poor mechanical stresses acting on the bone with an increase in urinary calcium excretion. In general, exercise during growth, creates a skeleton composed of denser, stronger bone that is better able to withstand stress^28,29.

Exercise started in childhood is also very important in the prevention of obesity. Obesity is known to be related to an increased risk of more than 20 diseases such as hypertension, coronary heart disease, diabetes, hyperlipidemia, cholelithiasis, cancer, and osteoarthritis. When several risk factors are combined, the overall risk is many times greater. Obesity induces serious psychological effects as well. Obese people can have less muscle mass than people of normal weight if not active. In addition, the cardiovascular demands of activities are greater in the obese²⁸. Limitation of physical activity may contribute to begin a vicious cycle. The prevention of obesity is particularly important during periods of rapid growth, as fat cells multiply during these times. Body fat tissues can be enlarged by increasing either the amount of fat stored in each cell or by increasing the number of cells in adipose tissue. The number of fat cells seems to increase up to about 16 years of age, after which increased fat ordinarily accumulates by increasing the size of cells already present. Fat cell number does not decrease with weight loss, but the size of the cells can be dramatically reduced by diet and exercise. Obesity of childhood onset is the most severe and is characterized by adipose tissue which contains 4-5 times the number of fat cells as people of normal weight. Approximately 80% of obese children remain obese as adults and thus the outcome of obesity treatment is much more likely to be difficult and negative³⁰. Body fat of students who exercise regularly compared to less physically active students is often lower and lean body mass tends to be higher³¹. Percentages of body fat of elite national gymnasts were significantly less than those of provincial athletes²⁶ (Fig. 2).

The evidence shows that regular exercise and appropriate diet may prevent the development of fat cells and thus be a factor in lifelong weight control^28,30. Exercise not only promotes growth and development of bone and muscle, it also enhances the growth of muscle strength and improves muscle coordination capacity through the central nervous system. Thus, children and adolescent athlete 1000 s are much stronger in coping with physical load and stress than less active children, and the onset of fatigue comes late in athletes with physical load^28,30. Therefore, the fostering of regular exercise habits early in childhood can play an important role in the life-long maintenance of health. Medical professionals, parents, and educators should ensure that children grow into accomplished and secure adults by encouraging physical activity.

Conclusions

1. The benefits of exercise are:

1. Exercise may reduce the risk factors for chronic diseases such as obesity, coronary heart disease, diabetes, and osteoporosis.
2. Exercise may improve human functional status and metabolism.
3. Exercise improves psychological status and capacity to cope with stress.

2. Adequate physical load defined scientifically and rational nutrition are the prerequisites for exercise. Malnutrition such as iron or zinc deficiency, not only affects work capacity, but also induces an increase in lipid peroxide levels and impairs immune function. Long term food restriction is harmful for adolescent athletes and should be discouraged.

3. The fostering of regular physical activity habits early in childhood can play an important role in the maintenance of health and quality of life. Physical exercise stimulates bone and muscle development. Exercise during growth creates a skeleton composed of denser, stronger bone and muscle mass that is better able to withstand stress because muscle strength is improved. Exercise started in childhood helps prevent obesity and is crucial for good mood and psychological state.

---

Benefits of physical activity on nutrition and health status: Studies in China

Chen Ji-Di

Asia Pacific J C Nutr (1995) 4, Suppl 1

---

References

1. James WPT. The role of nutrition and fitness in chronic diseases. Am J Clin Nutr 1989(suppl); 49(5): 933-934.
2. Rontoyannis. Diet and exercise in the prevention of cardiovascular disease. In Simopoulos AP, ed, Nutrition and Fitness in Health and Disease, World Rev Nutr Diet. Basel, Karger, 1993; 72: 9-22.
3. Antonini FM, Vannucci A. Exercise and nutrition in the elderly. In: Fabris F, Pernigotti L, and Ferrario E, eds, Sedentary Life and Nutrition, New York: Raven Press, LTD, 1990; 38: 89-94.
4. Ferrario E, Visentin P, Pernigotti, and Fabris F. Metabolic modification after physical activity. In: Fabris F, Pernigotti L, and Ferrario E, eds, Sedentary Life and Nutrition, New York: Raven Press, LTD., 1990; 38: 95-101.
5. Li Z-Y, Ding Z, Liu J-B. The dynamic observation on cardio-pulmonary function of adolescent middle and long distance runners during submaximum exercise. Chinese J Sports Med 1984; 3: 225-230.
6. Feng H-L, Li S-J, Cheng M-Y, Li Y-Z. Effects of 8 months systematic training on cardiac function of 41 five to six years old children. Chinese J Sports Med 1991; 10(2): 112-113.
7. Yin Y-P. Effect of jogging on microcirculation of nail fold in the aged. Chinese J Sports Med 1993; 12(4): 240-242.
8. 1000 Chang W-Y, Jia S-Y, Wang J-L et al. Health effect of 2-5 years Dao-Yin preserve skill practice on cardiovascular system of 31 middle and old aged people. Chinese J Sports Med 1990; 9(3): 183-184.
9. Zheng Y-M, He T-M, Chang L-F. Observation on serum lipids of exercise and no exercise aged people. Chinese J Sports Med 1992; 11(1): 57-58.
10. Toshitaka T, Mitsuru H, Koji O et al. Effect of exercise on plasma lipoprotein metabolism. In: Sato Y, Poortmans J, Hashimoto I, Oshida Y, eds, Integration of Medical and Sports Sciences. Med Sport Sci. Basel, Karger, 1992; 37: 430-438.
11. Casper RC. Exercise and mood. In: Simopoulos AP, Pavlou KN, eds, Nutrition and Fitness for Athletes, World Rev Nutr and Diet. Basel, Karger, 1993; 91: 115-142.
12. Morgan WP, Costill DL, Flym MG et al. Mood disturbance following increased training in swimmers. Med Sci Sport Exerc 1988; 20: 408-414.
13. Farrell PA, Gustafson A, Morgan NP, et al. Enkaphalins, catechola-mines and psychological mood alterations: Effects of prolonged exercise. Med Sci Sports Exerc 1987; l9: 347-353.
14. Kraemer RR, Dzewaltowski DA, Blair MS, et al. Mood alteration from treadmill running and its relationship to beta-endorphin, corticotrophin, and growth hormone. J Sports Med Phys Fitness 1990; 30: 241-246.
15. Chen J-D, Li K-J, Chen Z-M et al. Study on anemia of athletes. Chinese J Sports Med 1990; 9(4): 193-197.
16. Zheng B-Y, Yan L-Y. Effects of mild iron deficiency anemia on children's physical work capacity. Acta Nutrimenta Sinica 1988; 10(1): 39-45.
17. Li R-W, Chen X-C, Yan H-C, et al. Effects of iron supplementation on production, efficiency of iron deficient female textile worker. Acta Nutrimenta Sinica 1993; 15(1): 32-37.
18. Chen J-D, Li K-J, Chen Z-M, et al. Study on iron status and its related factors in adolescent athletes. Chinese J Sports Med l990; 9(3): 140-144.
19. Chen J-D, Wang J-F, Wang S-W, et al. Recommended dietary allowances for Chinese athletes, suggestions and illustrations. In Sato Y, Poortmans J, Hashimoto I, Oshida Y, eds, Integration of Medical and Sports Sciences. Med Sport Sci. Basel, Karger, 1992; 37: 336-341.
20. Chen J-D, Liu X-P, Tao Z-L, Wu L, Chen Z-M, et al. Effects of iron deficiency anemia and exercise load on erythrocyte damage in rats. In: Biochemistry of Exercise 9th International Conference, Aberdeen; 1994: 86.
21. Cao G-H, Chen J-D. The effects of one bout of acute exercise on the free radical generation and the free radical defense system in humans. Chinese J sports Med l991; 10(1): 1-3.
22. Cao G-H, Chen J-D. The effects of swimming training on the free radical formation and the free radical elimination in mice. Chinese J Sports Med l991; 10(2): 65-68.
23. Cao G-H, Chen J-D. Free radical generation and elimination in athletes and their relation to zinc and copper status. Chinese J Sports Med l991; 10(3): 132-135.
24. Cao G-H, Chen J-D. Effect of zinc deficiency on the free radical generation and the free radical elimination in exercised mice. Chinese J Sports Med 1991; 10(4): 205-210.
25. Feng J-Y, Chen J-D. Effect 9d7 of exercise and zinc deficiency on marine immune function. Chinese J Sports Med 1994; 13(2): 88-92.
26. Chen J-D, Yang Z-Y, Jiao Y, Bai R-Y, Chen Z-M, Wu Y-Z. The nutrition and body composition of girl gymnasts during weight control. J Sports Sci (in Chinese) 1987; 7: 22-25.
27. Chen J-D. Medical problems of rapid weight and long term weight control in athletes. In: Tsopanakis A and Poortmans J, eds. Physiological Biochemistry of Exercise and Training, Proceedings 3rd International Course. Athens: Hellenic Sports Research Institute, Olympic Sports Center of Athens, 1986, 257-266.
28. Brooks GA. Growth and Development. In: Brooks GA, Fahey TD, eds. Exercise Physiology, Human Bioenergetics and Its Application. New York, Chichester, Brisbane, Toronto, Singapore: John Wiley and Sons, Inc., 1984, 661-680.
29. Campagnoli C, Belforte P, Bracci T, Isaia G. Prevention and therapy of postmenopausal osteoporosis, role of nutrition and physical activity. In: Fabris F, Pernigotti L, Ferrario E, eds. Sedentary Life and Nutrition. Raven Press: 1990, 125-135.
30. Lamb DR. Exercise, body composition and weight control. In: Lamb DR, ed, Physiology of Exercise, Responses, and Adaptations, 2nd ed, New York, London: Macmillan Publishing Company, 1984,121-134.
31. Zheng SQ. Measurement of body composition and equation for estimating the percentage of fat in college students. Chinese J Sports Med 1984; 3(2): 76-78.

Copyright © 1995 [Asia Pacific Journal of Clinical Nutrition]. All rights reserved.
Revised: January 19, 1999 .

 

 

 

 

 

 

 

 

 

0