[The use of drugs to improve athletic performance]

In sports, medical drugs are applied for supposedly ergogenic effects. Forbidden drug use (doping) implies that the drug enhances performance, which is not always the case. Amphetamines are ergogenic particularly during short-term, explosive exercise. Amphetamines exert an ergolytic effect on high-intensity endurance exercise. Caffeine has an ergogenic effect on endurance performance in dosages of 3 to 6 mg/kg. Doping regulations allow a small amount of caffeine intake. Androgenic and anabolic steroids elicit an increase in muscle growth and strength. In females low doses appear to be ergogenic in all sport types. beta 2-adrenergic agonists appear to have a positive effect on strength and muscle growth. The effects on endurance performance are still unknown. Although growth hormone is used in sports, scientific studies show that compared with placebo no difference in strength and muscle volume is observed. Blood doping and administration of erythropoietin are effective in enhancing endurance performance.

Impaired IgG-dependent anaphylaxis and Arthus reaction in Fc gamma RIII (CD16) deficient mice

The family of receptors for IgG (Fc gamma R) plays an essential role in antibody-mediated effector functions of the immune system. However, the specific contribution of each of the Fc gamma R classes to in vivo immune reactions is still unclear. Here, we demonstrate that mice deficient for the ligand-binding alpha chain of Fc gamma RIII lack NK cell-mediated antibody-dependent cytotoxicity and phagocytosis of IgG1-coated particles by macrophages. Strikingly, these mice lack IgG-mediated mast cell degranulation, are resistant to IgG-dependent passive cutaneous anaphylaxis, and exhibit an impaired Arthus reaction. These results indicate a prominent role for Fc gamma RIII in inflammatory and anaphylactic responses, making this receptor a potential target in immunotherapy.

Body composition, cardiovascular risk factors and liver function in long-term androgenic-anabolic steroids using bodybuilders three months after drug withdrawal

The purpose of this study was to investigate in a cross-sectional design body composition, muscle fiber characteristics, cardiovascular risk factors and liver enzymes in long-term androgenic-anabolic steroids (AAS) using bodybuilders three months after drug withdrawal (AAS group; n = 16) and in non-users (CO group; n = 12). Training and dietary data were collected in all subjects. Anthropometry included weight, height, 8 skinfolds and 11 circumferences. Percentage fat (%FAT), fat mass (FM) and lean body mass (LBM) were calculated. In a muscle biopsy from the vastus lateralis muscle water content, fiber type distribution and diameters of fiber type I and type II were determined. Age, height, training characteristics, nutrition, skinfolds, %FAT and FM did not differ between the groups. The AAS group had greater BW and LBM, and larger circumferences of thorax, waist, upper arm and thigh than the CO group. Muscle biopsy data were comparable, except for muscle fiber diameter of type I which was larger in the AAS group. No differences in serum values of total cholesterol, HDL-cholesterol and triglycerides, nor in systolic and diastolic blood pressure were observed. In both groups serum alkaline phosphatase and gamma GT were within the normal range. This study suggests that in long term AAS using body-builders, after a three months AAS free period, BW is greater than in non drug users. This is reflected in larger LBM, circumferences and diameter of muscle fiber type I. In addition, no differences in fat mass, blood pressure, lipoprotein profiles and liver enzymes exist between AAS users three months after interrupted drug use and their non drug using counterparts.

Structural muscle damage and muscle strength after incremental number of isometric and forced lengthening contractions

Exercise-induced muscle damage is characterized by histological changes, like Z-line streaming, inflammatory response and decreased muscle function reflected in a prolonged decline in maximal isometric muscle strength after eccentric work. It is assumed that force decrement is mainly related to the amount of structural damage. However, the relationship between number of eccentric contractions, magnitude of structural damage and force decrement is not very well documented. Therefore we studied the effect of an increasing number of both isometric and eccentric (forced lengthening) contractions on histological parameters of muscle damage and maximal isometric force in an experimental in situ rat model. Tibialis anterior muscles of male Wistar rats were subjected to an increasing number of either isometric or eccentric contractions and were examined for histological markers of muscle damage. The present study shows that muscle damage increases progressively with the number of forced lengthening contractions. Maximal isometric torque was found to decline after both types of exercise. However, the decline after forced lengthening exercise was more pronounced. Only a weak relationship between percentage of histological muscle damage and isometric torque after forced lengthening contractions was found. The findings of the present study suggest that the decline in muscle force after eccentric exercise may partly be attributed to other factors than structural damage.

Glucose and insulin responses after commonly used sport feedings before and after a 1-hr training session

This investigation examined the plasma glucose and insulin response in 6 trained athletes after consumption of four commercially available sport feedings 2 hr before as well as immediately after 1 hr of running under common training conditions. Four feedings were compared: Feeding 1, 160 g CHO/400 ml; Feeding 2, 69 g CHO/400 ml; Feeding 3, 69 g CHO + 6 g protein/400 ml; and Feeding 4, solid 69 g CHO + 5 g protein + 4 g fat. Before the training session, there were no differences between the four sport feedings in the area under the glucose and insulin curves and the insulin/glucose ratio. However, after exercise, Feeding 2 resulted in a significantly greater area under the glucose curve compared with Feedings 1, 3, and 4 (respectively, 352 vs. 241, 251, and 182) and a significantly lower insulin/glucose ratio compared with Feeding 1 (respectively, 6.2 vs. 15.8). Therefore, it is concluded that the kind of sport feeding may influence postexercise glucose and insulin responses.

Overtraining following intensified training with normal muscle glycogen

The purpose of this study was to determine if consumption of appropriate amounts of carbohydrate during a period of increased exercise training would protect the athletes from becoming overtrained. Eight male competitive cyclists were monitored and tested during three training periods: a) normal training (moderate intensity, long duration, 7 d, NORM); b) overtraining (high intensity training, 15 d, OVER); and c) recovery (minimal training, 6 d, REC). Throughout the training 160 g of liquid carbohydrate were consumed within the first 2 h after the daily exercise bout. Mean dietary intake (NORM = 13.7 +/- 1.6, OVER = 14.1 +/- 1.0 MJ.d-1) and carbohydrate percent (NORM = 64.0 +/- 2.1, OVER = 67.4 +/- 2.5%) were not different during the different training periods. Similarly, resting muscle glycogen levels were not different (NORM = 530.9 +/- 42.5, OVER = 571.2 +/- 27.5 mumol.g-1 dry weight). Five criteria were used to determine if overtraining occurred in a subject (decreased maximal workload, maximal heart rate, ratio of maximal lactate to rating of perceived exertion (HLa:RPE), and resting plasma cortisol levels, increased affirmative response to a daily questionnaire). All subjects met at least three of the five criteria and thus were classified as overtrained. Therefore, short-term overtraining may occur even when resting muscle glycogen levels are maintained.

Beta-adrenoceptor blockade and skeletal muscle energy metabolism during endurance exercise

Twelve healthy male volunteers cycled to exhaustion at a workload corresponding to 70% of maximal aerobic power after administration of 80 mg of the beta 1+2-adrenoceptor antagonist propranolol and after administration of placebo by mouth. Exercise times until exhaustion were 39 +/- 7 and 86 +/- 7 min in the propranolol and placebo groups, respectively. Muscle inosine 5'-monophosphate content was significantly increased above resting levels at exhaustion after placebo. At exhaustion after propranolol, inosine 5'-monophosphate was not increased significantly and was lower than at exhaustion after placebo. No changes in ATP and the total adenine nucleotide content during exercise were found in the two tests. Muscle glycogen content was significantly reduced at exhaustion after placebo as well as after propranolol, but the levels were still significantly higher at exhaustion after propranolol than after placebo. No evidence for a shift in glycogen utilization among types I, IIa, and IIb fibers after propranolol was found. The results show that neither an imbalance between ATP utilization and ATP regeneration nor premature glycogen depletion, either in the whole muscle or in specific muscle fiber types, provides a satisfactory explanation for the premature fatigue during endurance exercise after propranolol.

The relation between power output, oxygen uptake and heart rate in male athletes

As the exercise intensity is often expressed as percentage of either maximal workload (%Wmax), percentage of maximal heart rate (%HRmax), or as percentage of maximal oxygen uptake, the relationship between %Wmax, %VO2max, and %HRmax was determined in 53 male cyclists. All subjects performed an incremental maximal cycle ergometer test. In all athletes examined, a linear relation between power output, oxygen uptake and heart rate was observed. The relationships between %Wmax and %VO2max as well as between %Wmax and %HRmax were linear (r = 0.98 and r = 0.97; p < 0.001). It is concluded that studies which are different in expression of exercise intensity (%Wmax or %VO2max) can be compared and that the relation between %Wmax and %HRmax needs to be determined individually when an appropriate individualized training intensity based on heart rate is required.

Adaptation and overtraining in horses subjected to increasing training loads

To evaluate markers for overtraining, seven male race horses were subjected to 272 days of training consisting of daily exercise bouts of either endurance running (heart rate 140/min) or interval training (maximal heart rate), both increasing in duration and intensity. An incremental exercise test was held every 4 wk, and from day 187 it was held every 2 wk. Muscle glycogen, muscle lactate, energy-rich phosphates, adrenal response to adrenocorticotropic hormone, plasma and red blood cell volumes, and a number of blood chemical variables were measured. The horses showed symptoms of weight loss, irritability, and an inability to complete the training after the intensity of the endurance exercise was increased. Test performance was not decreased. The adrenal response to adrenocorticotropic hormone was not changed during overtraining. The decline in muscle ATP concentration during maximal exercise was less during the period of staleness, whereas plasma volume, red blood cell volume, and blood chemical variables were unchanged. It was concluded that as long as exhaustive training is alternated by light exercise, overtraining is unlikely to occur. Furthermore, no single parameter can be used to detect early overtraining.

Exercise-induced muscle damage

Muscular overuse is associated with structural damage of the contractile elements and reflected in delayed onset muscle soreness (DOMS). Mechanical stress is supposed to be the major contributing factor for inducing muscle damage. The initial damage is followed by an inflammatory response and eventually by regeneration. Calcium is assumed to play an important role in triggering the inflammatory changes. Biopsy data in man indicate that the inflammatory changes in humans do not parallel the soreness ratings, leaving the delayed onset of muscle soreness unexplained. It is a well known phenomenon that one bout of eccentric exercise has a long lasting protective effect against damage induced by a second bout of exercise. Experimental evidence suggests that this adaptation can partly be attributed to an increase in connective tissue. Plasma CK activity has widely been used as a marker for the amount of muscle damage. It has been shown that gender differences in exercise-induced CK release are caused by sex hormones dependent differences in sarcolemmal permeability. Plasma CK activity does not necessarily reflect the amount of structural damage.

Effect of exercise training on ambulatory blood pressure

A possible hypotensive action of regular endurance exercise in normotensive sedentary subjects still remains a matter of debate. This is partly caused by the fact that the anticipated fall in resting blood pressure is rather small and fluctuations in blood pressure during the day can be large. The benefits of ambulatory blood pressure monitoring (ABP) originate to a great deal from the fact that the repeatability on different occasions of the ambulatory blood pressure average is improved by the greater number of readings. In this context we evaluated the effect of moderate exercise training in 19 sedentary male subjects, aged 22 to 44 years, with normal or slightly elevated blood pressure. They entered a randomized cross-over study. Measurements were performed before the study, after 6 weeks of sedentary life style (S) and after 6 weeks of training (T) on a cycle ergometer 3 times a week for 45 min at 75% VO2max. ABP was measured with a Spacelabs 90207 monitor and cardiac output at rest with echo-Doppler. Training increased VO2max from 3.13 +/- 0.09 to 3.40 +/- 0.08 l/min (p < 0.01). Resting heart rate decreased from 60 +/- 2 to 57 +/- 2 bpm (p < 0.05). Resting blood pressure was unchanged after training. Resting stroke volume increased from 82 +/- 3 to 89 +/- 3 ml (p < 0.02). Systemic vascular resistance index was significantly decreased due to conditioning (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

A short cycle ergometer test to predict maximal workload and maximal oxygen uptake

In order to develop a short cycle ergometer test for the prediction of maximal oxygen uptake (VO2max) and maximal work load (Wmax) oxygen uptake, workload and heart rate data were collected in 22 subjects. In the first test the subjects cycled at two submaximal stages of 3 min each whereafter the workload was quickly (within 4 min) increased to a supramaximal level to attain the maximal heart rate. A second graded cycle test was used to compare observed Wmax and VO2max with estimated Wmax and VO2max. The means of the estimated Wmax and observed Wmax were 364.9 (SD +/- 42.4) watts and 368.8 (SD +/- 40.2) watts, respectively and the mean estimation error was -1.0% (range -7.1% to 4.4%). For 82% of the subjects the estimation error was within +/- 5%. The means of the estimated VO2max and observed VO2max were 4.49 (SD +/- 0.45) l.min-1 and 4.59 (SD +/- 0.41) l.min-1, respectively. The mean estimation error was -2.1% (range -13.8% to 5.1%). For 68% of the subjects the estimation error was within +/- 5%. It is concluded that for trained athletes the short test (8-10 min) is accurate for the estimation of Wmax and VO2max by measuring two submaximal heart rates and maximal heart rate and making use of the linear relationship between heart rate, workload and oxygen uptake.

Modulation of glycogen metabolism of rat skeletal muscles by endurance training and testosterone treatment

The effects of training and/or testosterone treatment on glycogen content and the activities of glycogen synthase, glycogen phosphorylase, and fructose-6-phosphate kinase were studied in extensor digitorum longus (EDL) and soleus muscles of intact adult female rats. One group of rats remained sedentary, whereas another group was trained for 7 weeks. Thereafter, both the sedentary and trained rats were subdivided into two control and four testosterone-treated subgroups. Testosterone was administered by a silastic implant. Training was continued for 2 weeks. On the final day of the experiment rats from one trained control and one trained testosterone-treated subgroup ran for 60 min submaximally. Upon testosterone treatment of sedentary rats the glycogen concentration was not changed. However, in the soleus, but not in the EDL, the glycogen content was increased by training (P < 0.05) which could, at least partly, be explained by a decrease in activity of active glycogen phosphorylase (P < 0.05). In the EDL of trained rats testosterone treatment increased glycogen content significantly by both an increase in activity of active glycogen synthase and a decrease in activity of active glycogen phosphorylase (P < 0.05). In the EDL and soleus of testosterone-treated animals from the exercised subgroup a significant sparing of glycogen was observed, which could be explained by an increase in activity of active glycogen synthase and, in the soleus, could also be explained by a concerted decrease in active glycogen phosphorylase (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)