The power output/heart rate relationship in cycling: test standardization and repeatability.

PURPOSE: The purpose of this study was to update and standardize the test for determining the power output/heart rate (PO/HR) relationship in cycling. METHODS: The current protocol was developed in the laboratory using a wind-load cycling simulator. Five hundred incremental tests were carried out by 290 male cyclists during a 2-yr period (1995-1997). The subjects' own bicycles, equipped with a standard crankset with a built-in power measuring system, were used for testing. The test protocol consisted of time-based increments in cadence that were uniform up to submaximal speeds and progressively greater in the final phase. RESULTS: The PO/HR relationship obtained was linear at low to submaximal PO and curvilinear from submaximal to maximal PO. A method was developed for the mathematical identification of the point of transition from the linear to the curvilinear phase (deflection point or heart rate break point). In 484 of the 500 tests performed, the deflection was independent of the final acceleration (PO at deflection 318.4 +/- 42.4 W, PO at final acceleration 351.6 +/- 43.2 W, P < 0.001), whereas in 16 tests the deflection and the start of the final acceleration coincided. To evaluate test repeatability and precision, 15 subjects repeated the test twice within a few days. No significant differences were found for the heart rate at deflection, power output at deflection, or slope of the linear part of the PO/HR relationship obtained in the two tests. CONCLUSION: It is concluded that the deflection point obtained by determining the PO/HR relationship on a wind-load simulator is not an artifact dependent on the incremental test protocol but rather a repeatable physiological phenomenon.

Use of calcium provocative test in the diagnosis of gastroenteropancreatic endocrine tumors.

Calcium infusion has been advocated as a provocative test for the diagnosis of some endocrine tumors of the pancreas and gastrointestinal tract (gastrinoma, insulinoma, intestinal carcinoids). The release of gastrin from gastrinoma tissue is very sensitive to alterations in the serum calcium level, and the calcium infusion test is recommended in Zollinger-Ellison syndrome when the results of secretin stimulation are equivocal. The calcium provocative test in the detection of insulinoma and carcinoid tumors is less reliable than other safer and simpler procedures. Intravenous injection of calcium followed by pentagastrin stimulates the release of somatostatin in patients with somatostatinoma and offers a reliable means for establishing the diagnosis of this tumor. Calcium administration has not proven to be useful in the diagnosis of other endocrine tumors of the digestive system.

Reduction of erythrocyte magnesium concentration in heterozygote beta-thalassaemic subjects and in normal subjects submitted to physical stress.

Erythrocyte and serum magnesium (Mg) concentrations have been assayed in a group of sedentary heterozygote beta-thalassaemic subjects (beta-thal), in a group of non-thalassaemic well trained runners before and after a 25 km running race, and in a group of sedentary healthy controls. The mean erythrocyte Mg concentration (EMg) found in beta-thal (2.72 mEq/litre) and in runners, both before and after the race (2.58 mEq/litre before, 3.10 after), was significantly lower than the EMg values from the control group (3.69 mEq/litre). We propose various hypotheses to explain the reductions observed.

A field test for determining the speed obtained through anaerobic glycolysis in runners.

A field test for the evaluation of the speed generated by the anaerobic lactacid mechanism has been developed in runners. The test consists of 1200 m of continuous running: in the first 1000 m the speed corresponding to the anaerobic threshold is progressively reached; in the last 200 m an all-out sprint is performed. The speed at the anaerobic threshold is subtracted from the speed reached in the final 200-m all-out sprint. In 39 runners examined (marathon runners, n = 13; 5000-10000-m runners, n = 10; 400-800-m runners, n = 7; sprinters, n = 9), the additional speed generated above the anaerobic threshold was correlated with the venous blood lactate concentration reached 5 min after the all-out effort (r = 0.93). The anaerobic speeds measured by the test were in keeping with the characteristics of the runners under study, i.e., anaerobic speeds were highest for the sprinters, intermediate for the middle-distance runners, and lowest for the marathon runners. Since the speed generated above the anaerobic threshold by the aerobic fuel breakdown can be subtracted, the contribution of creatine phosphate is minimal, and the speed exceeding the anaerobic threshold is highly correlated with lactate accumulation, the present test should measure the speed generated by anaerobic glycolysis.

Reduction of Hb levels during the racing season in nonsideropenic professional cyclists.

Hematological variables of 40 professional cyclists, all receiving intravenous iron supplementation, were followed during a 15-month period. Mean values for red blood cells (RBC), hemoglobin (Hb), and hematocrit (Ht) were significantly lower during the racing season (RS) than during the nonracing periods (NRP) (RBC: RS = 4.53 +/- 0.34 millions/mm3, NRP = 5.09 +/- 0.36 millions/mm3; line 7 of abstract: Hb: RS = 14.2 +/- 0.9 g/dl, MRS = 15.2 +/- 0.9 g/dl; Ht: RS = 40.7 +/- 2.7% NRP = 44.4 +/- 2.9%; P less than 0.001 for all). However, mean values for ferritin and mean corpuscular hemoglobin (MCH) were significantly higher during the racing season (ferritin: RS = 422 +/- 398 ng/ml, NRP = 311 +/- 321 ng/ml, P less than 0.05; MCH: RS = 31.5 +/- 1.3 pg, NRP = 30.0 +/- 1.4 pg; P less than 0.001). These results suggest that the reductions in RBC, Hb, and Ht found in professional cyclists during the racing season are not the consequence of a diminution of iron stores but rather of reduced erythropoiesis and increased RBC destruction.

Reduced hemoglobin concentration and red cell hemoglobinization in Italian marathon and ultramarathon runners.

Red blood cell indices, serum iron, and serum ferritin concentration were determined in 45 marathon runners, 56 ultramarathon runners, and 32 healthy sedentary controls. A significant reduction of hemoglobin concentration, hematocrit, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, mean corpuscular volume, serum iron, and serum ferritin were found in marathon runners compared to control subjects. The same variables were also reduced, but to a lesser extent, in the less trained ultramarathon runners. The decreased hemoglobin concentration demonstrated in the runners examined is related to both a reduced mean corpuscular hemoglobin concentration and a reduced hematocrit and may depend on a reduction of the body iron stores.

Changes of magnesium concentrations in endurance athletes.

Erythrocitary and serum magnesium (Mg) were determined in a group of 11 well-trained athletes before and after a 25-km running race, and in a group of 30 sedentary controls. The significant increase of mean erythrocitary Mg (EMg) concentration observed in the athletes after physical strain (2.58 +/- 0.34 mEq/l before, 3.10 +/- 0.45 mEq/l after the race: significance level = 5%) leads to the assumption that the possible Mg uptake is effected by the red blood cell to enhance some enzymatic reactions. The decrease of mean serum Mg concentration observed in the same subjects after the effort (1.70 +/- 0.14 mEq/l before, 1.64 +/- 0.15 mEq/l after the race) is not significant. The difference between mean Mg concentrations observed in the athletes' group before the race and in the sedentary group (EMg: 2.58 +/- 0.34 mEq/l in athletes, 3.67 +/- 0.38 mEq/l in sedentaries, significance level = 1%; serum Mg: 1.70 +/- 0.14 mEq/l in athletes, 1.96 +/- 0.15 mEq/l in sedentaries, significance level = 1%) suggests that athletes suffer from a Mg deficiency, partially due to physical exercise. The two hypotheses and the possible causes of the observed phenomena are discussed.

[Hematological variables in marathon and ultramarathon runners]. / Variabili ematologiche in maratoneti ed ultramaratoneti.

The haemoglobin concentration of runners has been reported to be often below normal (1). In the present investigation the haemoglobin and iron concentrations and the haematocrit have been determined in 45 marathon runners examined before and after the 1982 Italian Marathon Championship and in 79 runners examined before and after the 1982 Firenze-Faenza race (107 km). The results obtained suggest that the training programs followed by the marathon runners (up to 260 km per week in the months preceding the race) are accompanied by a significant decrease of the haemoglobin and iron levels and of the haematocrit. Similar results have been observed in the participants to the Firenze-Faenza race. Nevertheless in these ultramarathoners the decrease of the haemoglobin and iron concentration and of the haematocrit are less marked, possibly because their training programs are less intense than those of the marathon runners. The findings obtained are in favour of the hypothesis that the degree of "sport anaemia" might be related to the amount of training of the athletes.

Serum erythropoietin in cross-country skiers.

Serum erythropoietin (Epo) activity, hemoglobin (Hb), and hematocrit (Ht) were determined in 21 cross-country skiers during the training season. The Epo levels were not significantly reduced in the skiers relative to the normal population (P less than 0.01 and P less than 0.001, respectively). In 11 athletes Epo, Ht, urinary gamma-glutamyltransferase, N-acetyl-beta-glucosaminidase, and microalbuminuria were determined before and after a 50-km ski race at 1600 m above sea level. A significant increase of these variables (except for Ht) was found after the competition (P less than 0.001). It is concluded that while the reductions in Hb and Ht, which are typical of several endurance exercises, are not accompanied by a renal hypoxia sufficient to stimulate Epo overproduction, the renal hypoxia reached during the strenuous exercise of the race at altitude may be effective in determining blood increases in Epo.

Noninvasive determination of the anaerobic threshold in canoeing, cross-country skiing, cycling, roller, and ice-skating, rowing, and walking.

The relationship between velocity (V) and heart rate (HR) was determined in four canoeists, 42 cross-country skiers, 73 cyclists, nine ice-skaters, 10 roller-skaters, 32 rowers, and 20 walkers. The athletes were asked to increase their work intensity progressively, from low to submaximal velocities; HRs were determined by ECG in roller-, ice-skating, and walking, or read on a cardiofrequency meter in canoeing, cross-country skiing, cycling, and rowing. In all the athletes examined the linearity of the V-HR relationship was maintained up to a submaximal speed (deflection velocity, Vd), beyond which the increase in work intensity exceeded the increase in HR. Vd and anaerobic threshold (AT), determined through blood lactate measurements, were coincident in 19 athletes (6 cross-country skiers, 3 cyclists, 2 roller-skaters, 3 rowers, and 5 walkers). Vd was correlated with the average speeds maintained in walking (20 km, n = 13, r = 0.88), cross-country skiing (15 km, n = 20, r = 0.80; 30 km, n = 8, r = 0.82; 12 km, n = 7, r = 0.86; 11 km, n = 7, r = 0.86) and cycling (1,000 m flying-start, n = 68, r = 0.83), thus showing that AT is a limiting factor in these aerobic events.

The Conconi test: methodology after 12 years of application.

The protocol for the determination of the speed/heart rate relationship during incremental exercise previously described (so-called Conconi test) has been refined and in part modified during 12 years of application. The new protocol calls for time-based increments in exercise intensity that are uniform up to submaximal speeds and progressively greater in the final phase. As in the original article (18), the speed/heart rate relationship is linear at low to moderate speed and curvilinear from submaximal to maximal speeds. A method is presented for the mathematical definition of this relationship, with the calculation of the straight-line equation of the linear phase and the identification of the point of transition from the linear to the curvilinear phase (deflection point or heart rate break-point). Analysis of 300 tests selected at random from those in our data base (more than 5,000 tests) has enabled us to show that the speed at which the deflection point occurs is significantly lower (p < 0.001) than that at which the acceleration of the final phase begins. This fact demonstrates that the break-point is not brought on by the final acceleration called for in the test protocol. Analysis of the speed/heart rate relationship allows for the determination of the following additional functional indices: 1) maximal heart rate (in 21 athletes the maximal heart rate attained in the test and that attained while racing were equal); 2) range of heart beats defining the linear part of the speed/heart rate relationship; 3) range of heart beats from the deflection point to maximal heart rate; and 4) maximal aerobic exercise intensity, obtained through extrapolation of the straight-line equation to maximal heart rate. Data are provided on the conditions of the test subject that modify his speed/heart rate relationship, such as incomplete recovery from previous efforts, inadequate warm-up, or inadequate test procedure with too rapid increments in exercise intensity. Finally, criteria for test acceptability are presented.

Reproducibility of the Conconi test: test repeatability and observer variations.

The repeatability of the the speed/heart rate (S/HR) relationship obtained with the incremental test developed by Conconi et al. (5) was examined by having 75 subjects perform the same running test twice in the course of a few days. From the data obtained, comparisons were made of four variables: 1) speed of deflection, 2) heart rate of deflection, 3) slope, and 4) intercept on the y-axis of the linear portion of the S/HR relationship. Straight-line equations, correlation coefficients (r), and technical errors of measurement (TEM) were obtained by comparing data from the two successive tests. Data analysis suggests that in two successive tests there are some variations in the linear portion of the S/HR relationship. However, the straight lines obtained from the two tests converge at the same deflection point. The problem of assigning a single value to the point of deflection, when determined by means of visual analysis of the S/HR graph, was also examined. For this part of the study, speed and heart rate data previously obtained for 65 subjects were used. The selected tests had been carried out during the course of various studies. The 65 sets of test data were plotted on graph paper and given to six observers for independent evaluation of speed and heart rate of deflection. These observers had different levels of experience in interpreting Conconi test results. The speed and heart rate of deflection values assigned by each observer were compared to the values obtained through mathematical analysis of the tests by computer. Straight-line equations, correlation coefficients (r), and technical errors of measurement (TEM) obtained by comparing visually determined data to those determined through mathematical analysis were calculated for each observer. Only for observers with little experience were some differences found between the observer-assigned and computer-determined results; these differences occurred for both speed and heart rate of deflection. We conclude that visual analysis provides information that is very similar to that obtained through computer analysis. The accuracy of the visually obtained information varies according to the observer's experience.

Unmodified performance in runners following anabolic steroid administration.

The effect of a low-dose treatment (10 mg/day) of stanozolol on the anaerobic threshold (AT) and on maximal velocity (Vmax) was studied in ten well-trained runners in a 6-week trial experiment. The serum levels of testosterone (T), interstitial cell-stimulating hormone (ICSH), and of follicle-stimulating hormone (FSH) were determined before, during, and after the steroid administration. No improvements of AT and Vmax were found. No improvement of the competition running times was observed during the experimental period. The ICSH and FSH serum concentrations did not change significantly, while a marked decrease of the T serum concentration was observed. It is concluded that a low-dose treatment of stanozolol, sufficient to depress the testicular function, does not improve athletic performance.

Hematological indices of erythropoietin administration in athletes.

Recombinant human erythropoietin (EPO), commercially available since 1988, is thought to be used by athletes in aerobic sports for the purpose of increasing oxygen transport and aerobic power. In an attempt to identify EPO administration, we have studied the peripheral blood of 20 subjects practising sports at an amateur level. Automated cytometry was performed on the blood samples before and during 45 days of EPO treatment. The same hematological indices were determined for a control population that consisted of 240 elite athletes from various sports. As expected following EPO treatment, RBC, [Hb] and Hct increased significantly (increments of 8%, 6.3% and 11%, respectively). A significant increase in reticulocyte count was also observed. In addition, automated erythrocyte analysis showed a significant increase in cells with a volume > 120 fl and hemoglobin content (HC) < 28 pg (hypochromic macrocytes, or MacroHypo): 0.06 +/- 0.09% before EPO, 0.48 +/- 0.63% after EPO. The EPO-treated subjects differed from the control population having higher values for Hct, mean corpuscular volume (MCV), Macro and MacroHypo. To investigate the possibility of using such variations in blood parameters to identify EPO treatment, individual values for Hct, MCV, Macro and MacroHypo for treated subjects and controls were plotted. Using the percentages of MacroHypo, a cut-off value surpassed in approximately 50% of the treated subjects and in none of the controls was established.(ABSTRACT TRUNCATED AT 250 WORDS)

[Endurance of 6 marathon runners before and after a "dissociated diet"]. / Valutazione della resistenza di 6 maratoneti prima e dopo "dieta dissociata".

The effect of a carbohydrate loading diet on the endurance of six male marathon runners have been examined. Endurance improved in three runners, remained unchanged in two, and worsened in one. Due to the possibility of negative effects on the performance capability, a runner should experiment his personal reactions to the carbohydrate loading diet before using it regularly for long distance competitions.