Aerobics cause you to lose muscle

Aerobics causes you to lose muscle (Cook NJ et al. 1987 ; Dohm GL, Tapscott EB, Kasperek GJ 1987 ; Lindholm C et al 1995 l Maron MB, Horvath SM, Wilkerson JE 1975 ; Morville R et al 1979 ; Newmark ST et al 1976 ; Tegelman R et al. 1990 ; Tsai L et al 1991).One hour of aerobic exercise a day burns approx. 400 calories. When you stop the aerobics you gain fat because of your lowered metabolism (compounded by low calorie diets).

Extracts

Salivary cortisol for monitoring adrenal activity during marathon runs.

Cook NJ, Ng A, Read GF, Harris B, Riad-Fahmy D.

In non-elite male runners (n = 8) , changes in adrenal activity were monitored by measurement of salivary cortisol in samples collected at 4-mile intervals during marathon runs. These changes were compared with those in similarly timed samples collected on rest days. Immediately prior to the Cardiff marathon, at 09.00 h, mean salivary cortisol concentrations (21.5 nmol/l) were higher than those in similarly timed rest day samples (14.9 nmol/l). Cortisol concentrations increased during the marathon, and although values at 25 miles were high (79.4 nmol/l), maximum values (87.9 nmol/l) were observed in samples collected 30 min after completion of the run. Some Cardiff marathon runners also participated in the Bristol marathon (n = 4) and a non-competitive event (n = 3). The changing pattern in secretory activity was similar in all events. The easy collection of saliva without cessation of exercise is ideal for monitoring the hormonal response to exercise.

Protein degradation during endurance exercise and recovery.

Dohm GL, Tapscott EB, Kasperek GJ.

Department of Biochemistry, School of Medicine, East Carolina University, Greenville, NC 27834.

During endurance exercise, there is a net breakdown of body protein and the amino acids so mobilized are available for increased rates of oxidation and gluconeogenesis. At least part of the net loss of protein is due to a decrease in the rate of protein synthesis during exercise. Liver protein degradation is increased during exercise as a result of autophagy and proteolysis of cell material inside the secondary lysosomes. The rate of degradation of contractile proteins is decreased during exercise but is increased during the recovery period if the exercise is of high intensity and of long duration. Preliminary evidence suggests that the rate of degradation of non-contractile proteins in muscle may be increased at the same time that contractile protein degradation is decreased.

Altered adrenal steroid metabolism underlying hypercortisolism in female endurance athletes.

Lindholm C, Hirschberg AL, Carlstrom K, von Schoultz B.

Department of Obstetrics and Gynecology, Karolinska Hospital, Stockholm, Sweden.

OBJECTIVE: To explore possible changes in adrenal steroid metabolism and androgenic-anabolic status in female endurance athletes as a mechanism for their hypercortisolism. DESIGN: Adrenal steroids and androgenic-anabolic factors were studied during basal conditions and in response to ACTH stimulation related to menstrual status. SETTING: Department of Obstetrics and Gynecology, Karolinska Hospital, Stockholm, Sweden. PARTICIPANTS: Thirteen female elite middle to long distance runners (six eumenorrheic, seven oligoamenorrheic) and seven regularly menstruating controls. INTERVENTIONS: Blood samples were collected before and after an injection of 250 micrograms IV synthetic ACTH 1-24. Body weight, height, and body fat were measured. MAIN OUTCOME MEASURES: Basal serum concentrations of cortisol, androstenedione (A), DHEA, DHEAS, 17 alpha-hydroxyprogesterone (17-OHP), T, steroid-binding proteins, and insulin-like growth factor I and ACTH-induced response (area under the curve) of cortisol, DHEA, and 17-OHP. RESULTS: Oligoamenorrheic athletes had higher basal cortisol and A concentrations compared with healthy controls, whereas basal levels of DHEA and DHEAS were normal. Important findings in the oligoamenorrheic athletes were a significantly lower ratio between the ACTH-induced increments of DHEA and 17-OHP and an increased ratio between basal A and DHEAS. Insulin-like growth factor I was correlated negatively to sex hormone-binding globulin and to the amount of body fat in the combined material. CONCLUSIONS: The results indicate a redistribution of adrenal steroid metabolism in favor of glucocorticoid production in female endurance athletes. We suggest that hypercortisolism in female endurance athletes is a physiological adaptation to maintain adequate blood glucose levels during a condition of energy deficiency.

Acute blood biochemical alterations in response to marathon running

Michael B. Maron1, Steven M. Horvath1 and James E. Wilkerson1
(1) Institute of Environmental Stress, University of California, 93106 Santa Barbara, California

Received: 6 March 1975
Abstract Adrenal-sympathico function, blood carbohydrates and lipids, and water and electrolyte balance were studied in six highly trained male marathon runners prior to and after running a marathon (26.2 miles; 42.2 km) and on control days corresponding to the above times. Fluid intake was not sufficient to maintain body weight, the runners losing approximately 2.8 kg. Estimated plasma volume losses (161 ml, 4.4%) indicated that most of the fluid loss was extravascular.T re rose an average 2.4° C and a significant negative correlation between running time and rise inT re was observed. Glucose, free fatty acids, glycerol, hemoglobin, and plasma proteins were significantly elevated after the race. Small but statistically significant increments in lactate and pyruvate were also observed. Alterations in adrenalsympathico function were indicated by increased levels of cortisol, epinephrine, and norepinephrine.
Plasma variations in testicular and adrenal androgens during prolonged physical exercise in man.Morville R, Pesquies PC, Guezennec CY, Serrurier BD, Guignard M.

The evolution of the relationship between cortisol and testicular androgens was verified on two teams of respectively 10 and 9 male subjects (average age 34) running 100 km races in an average time of 14 hours. When compared to a control population of the same age, these trained athletes exhibited reduced testicular androgen levels (T and DHT) and increased adrenal androgen (delta 4) and cortisol levels with no significant alteration of LH. The period of recovery is characterized by rapid return to normal of the hormonal parameters whereas testosterone levels continue to increase in the following days. This hormonal picture, which reappears under certain pathological situations or when subjects are exposed to heavy stresses, seems to prove that the testicular androgens could be, both by their metabolic and psychic action, one of the limiting factors of physical aptitude to sustained effort.
Adrenocortical response to marathon running.Newmark ST, Himathongkam T, Martin RP, Cooper KH, Rose LI.

Plasma cortisol and plasma aldosterone levels were measured before and immediately upon completion of a marathon run in 7 highly conditioned male subjects in order to evaluate the response of the adrenal cortex to physical exertion. Both cortisol and aldosterone values rose significantly in response to the stress of the muscular exertion of the 26 mile, 385 yard run.
Endogenous anabolic and catabolic steroid hormones in male and female athletes during off season.

Tegelman R, Johansson C, Hemmingsson P, Eklof R, Carlstrom K, Pousette A.

Department of Clinical Chemistry, Karolinska Institutet, Huddinge University Hospital, Sweden.

Peripheral serum hormone levels during the off season were analysed in 10 male and 10 female athletes, all belonging to the Swedish national teams in skiing and orienteering and in age matched sedentary controls (15 males, 13 females). No clinical signs of overuse strain were observed in any of the athletes. No significant differences in hormone variables were found between male athletes and controls. The female athletes had significantly higher levels of cortisol and significantly lower ratios between total testosterone and cortisol, between non-SHBG-bound testosterone and cortisol and between 4-androstene-3, 17-dione and cortisol than the sedentary controls. The increased levels of cortisol found in the female athletes probably reflect an adaptation to several years of hard training. A decrease of the free T/cortisol ratio has earlier been shown to indicate an overuse distress. One may speculate that the low androgen/cortisol ratios found in the female athletes in contrast to the males could indicate that the female athletes might need longer time to recover from hard exercise than male athletes, or could suggest an insufficient dietary intake.