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Biomedical subjects

F Manfredini

Publications and source records attributed to F Manfredini.

At least 19 recordsLinked to original sources
PubMed2006

Exercise capacity and circulating endothelial progenitor cells in hemodialysis patients.

Mobilization of circulating endothelial progenitor cells (EPCs) is increased after acute exercise and training. This study aims to evaluate whether, in a low performance population, EPC levels may be related to exercise capacity in steady state conditions. Study population consisted of sixteen hemodialysis patients. The distance walked in the 6-minute walking test (6 MWD) and the maximal speed attained in an incremental treadmill test were used to assess the exercise capacity. Physical functioning was measured by the scale on the SF36 questionnaire. Quantification of peripheral blood CD34(+) cells and enumeration of EPCs, assessed as CD34(+) cells coexpressing AC 133 and vascular endothelial growth factor receptor-2, were performed. Hemoglobin concentration, white blood cells, high-sensitivity C-reactive protein, total cholesterol, and triglycerides were measured. Statistical analysis examined the relationship between blood progenitors cells versus performance parameters, laboratory parameters, age, body mass index, hemodialysis duration, and erythropoietin therapy. Univariate analysis revealed a significant association between percentage values of EPC and performance parameters only: 6 MWD (r=0.720; p=0.0017), maximal treadmill speed (r=0.721; p=0.0016), and physical functioning score (r=0.506; p=0.0453). A similar statistical association between EPC absolute values and performance parameters was found. No correlation between CD34 (+) and any parameter under study was observed. Multivariate analysis indicated 6 MWD as the most significant independent factor associated with EPC level. EPC percentage value was significantly lower (p=0.0087) in the worse (6 MWD < 300 m, n=8) than in the better performing group (6 MWD > 300 m, n=8). In a group of renal patients, mobilization of EPCs was related to the degree of exercise capacity, suggesting a possible connection with the cardiovascular risk in low performance populations limited by chronic diseases.

Aged↗
PubMed2004

Speed rather than distance: a novel graded treadmill test to assess claudication.

OBJECTIVE: To evaluate a new treadmill test, determining pain threshold speed (PTS) for use in assessment and measuring rehabilitation of patients with intermittent claudication. METHODS AND DESIGN: Twenty-nine patients with claudication were evaluated, and the ankle-brachial index (ABI) was assessed. PTS was determined with a treadmill protocol based on level walking, low starting speed, and progressive increments at a predetermined distance up to the onset of pain. Repeatability and equivalence with a time-based protocol were verified. PTS was compared to pain-free walking distance, 6-minute walking distance, and ABI. RESULTS: PTS was measured in all patients (3.6+/-1.1 km/h). Repeatability and equivalence between established tests were demonstrated. PTS showed a significant correlation with pain-free walking distance (r=0.833; P=0.0001), with 6-minute walking distance (r=0.724; P=0.005), and with ABI in the more ischemic limb (r=0.641; P=0.0001). CONCLUSIONS: PTS is a reliable parameter that correlates well with other established measures. It is useful for determining the degree of functional handicap and for designing and guiding rehabilitation protocols.

Aged↗
PubMed2004

Training guided by pain threshold speed. Effects of a home-based program on claudication.

AIM: To verify the effectiveness of a 120 day home-based program guided by the pain threshold speed (PTS). METHODS: Twenty-nine patients with stable claudication were measured for ankle pressure (AP), ankle-brachial index (ABI), PTS, maximal speed (Smax) on treadmill. Daily walking sessions at a speed 20-30% below PTS were prescribed. Determination of the training speed was supervised and facilitated at home. The program included a daily record of exercise data and symptoms, an intermediate PTS re-evaluation to adjust the training speed, and the reassessment of all the parameters after 120 days. RESULTS: Overall patients showed a reduction of systemic blood pressure (151.3+/-14.3 to 147.6+/-18.3 mmHg; 77.1 +/-9.1 to 72.4+/-8, p=0.008) while AP did not. ABI increased from 0.65+/-0.13 to 0.71+/- 0.18 (p=0.01). PTS and Smax rose from 3.2+/-1.1 to 4.2+/-1.5 km/h (p=0.0001) and from 3.9+/-1.3 to 4.6+/-1.3 km/h (p=0.0001), respectively. According to their compliance, patients were divided into 3 groups: 1) trained (T, n=14): exercise at the prescribed speed, 2) free-walkers (FW, n=7): walking speed markedly below PTS and 3) untrained (U, n=8): incomplete program compliance. T group showed symptom reduction up to pain disappearance. The ABI change (0.72+/-0.09 to 0.82+/- 0.16, p<0.02) was correlated to AP increase (r= 0.879). PTS and Smax rose from 3.6+/-1.1 to 5.4+/-0.8 km/h (p<0.02) and from 4.7+/-1.2 to 5.7+/-0.7 (p<0.02), respectively. FW showed improvement of all parameters, and U a better walking efficiency. CONCLUSIONS: In patients with claudication, a low-cost home-based program driven by PTS allows dramatic improvements of functional parameters.

Aged↗
PubMed2003

Blood tests and fair competition: the biathlon experience.

In recent years, some international sports federations have introduced blood testing procedures that can lead to suspension from competition for athletes whose haematologic values exceed certain established limits. In 1994 the International Biathlon Union initiated a three-phase blood testing program to safeguard athletes' health and ensure fair competition. The first phase, lasting three years, was aimed at measuring the haematocrit values of biathletes in order to determine statistically acceptable limits for participation in competition. The second phase, lasting four years, consisted of pre-race testing for an increasing number of athletes and suspension from competition for those whose haematocrit values exceeded 52 % for males and 48 % for females. The results of this second phase (third phase now in progress) are reported. Progressive increases have been made in the numbers of countries examined, athletes tested, and tests performed. This retrospective study reveals a reassuring trend in average values for haematocrit and haemoglobin in the entire study population, a minimal number of athletes with excessive values and a consequent low risk of false positive results, an acceptable incidence of relatively high values (50 % for males and 45 % for females), and constant non-elevated haematological profiles for elite athletes. The variability in individual haematocrit levels among all biathletes with a minimum of four observations during the four-year period is also evaluated and discussed.

Doping in Sports↗
PubMed2002

Competition load and stress in sports: a preliminary study in biathlon.

International sports calendars are being increasingly filled with competitive events and fatiguing travel, at the risk of overloading the athletes involved. The Medical Committee of the International Biathlon Union, in order to check for any significant changes, analysed seven recent competitive seasons, calculating the number of races and total and daily numbers of racing kilometers for each season. A theoretical model for stress was subsequently developed, based on identification and quantification of favourable and unfavourable factors, with establishment of average and maximal stress scores for each season. A questionnaire was distributed to athletes to collect data about daily stress levels, and the correspondence between the theoretical model and the athletes' responses was determined. This analysis demonstrates that the biathlon has become more demanding for those athletes in the racing circuit, with significant increases in number of races, total and daily numbers of kilometers raced, and average stress scores for athletes of both sexes. The self-reported daily stress levels for some athletes show an interesting correspondence with the theoretical stress model. If such correspondence is confirmed, this model might constitute an instrument with which international sports federations, considering the concentration of races, related travel and recovery times, could plan sustainable competitive calendars.

Adult↗
PubMed1999

Blood testing in biathlon: observation of hematocrit values during competitive periods 1994-1997.

The International Biathlon Union, through its own Medical Commission, has undertaken a three-year program aimed at identifying the hematocrit levels of athletes who participate in biathlons. The purpose was to check for hematocrit levels exceeding normal physiological values as well as for any significant modifications within individuals during the course of the competitive season. All of the athletes registered in international biathlon races were, therefore, subjected to venous blood sampling (1 cc) three times a year prior to competition, in the days preceding two World Cup races (December and January) and the World Championships (February). The blood was centrifuged, the micro-hematocrit determined, and the value (rendered anonymous) recorded. This procedure was repeated for three consecutive competitive seasons (Dec. 1994-Feb. 1995, Dec. 1995-Feb. 1996, Dec. 1996-Feb. 1997). During this three-year period, the collected data showed a significant lowering of the average hematocrit level. In fact, from the first February sampling to the third February sampling, the average hematocrit value for the male population dropped from 48.04 +/- 2.36 to 46.33 +/- 1.91, and for the female population from 44.05 +/- 2.44 to 42.52 +/- 1.92. Even the distribution of the absolute hematocrit values was modified from the first to the third competitive season, especially for the February sampling, with a > or = 50% reduction for males and a > or = 48% reduction for females.

Adolescent↗
PubMed1999

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.

Adolescent↗
PubMed1998

Circadian rhythms, athletic performance, and jet lag.

Rapid air travel across several time zones exposes the traveller to a shift in his/her internal biological clock. The result is a transient desynchronisation of the circadian rhythm, called jet lag, lasting until the rhythm is rephased to the new environmental conditions. The most commonly experienced symptoms are sleep disorders, difficulties with concentrating, irritability, depression, fatigue, disorientation, loss of appetite, and gastrointestinal disturbance. Apart from the decrements in mental and physical performance directly consequent on such symptoms, competitive athletes are also exposed to the additional negative consequences of a shift from the optimal circadian window of performance. A brief summary of the possible negative effects of jet lag on athletic performance and potentially alleviating strategies is given.

Adaptation, Physiological↗
PubMed1996

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.

Adolescent↗
PubMed1996

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.

Adult↗
PubMed1996

[Light-guided intubation using Trachlight].

BACKGROUND: A new intubating transilluminated device (Trachlight) has been recently proposed as an alternative to tracheal intubation with direct laryngoscopy. OBJECTIVE: 1) To evaluate Trachlight device in orotracheal intubation and to assess its operation and complications. 2) To compare the time consumption of transillumination intubation in respect to direct laryngoscopy on the same patients. METHODS: The first study was performed on 50 patients undergoing elective surgery and submitted to Trachlight intubation alone; speed of intubation, number of attempts and all complications were recorded and related to Mallampati classes. In the second study 16 patients undergoing to elective surgery were enrolled. Each patient was classified according to both the Mallampati classes and the Cormack classes. Each patient was submitted to two tracheal intubations: the first with the Trachlight and the second with conventional direct laryngoscopy performed by the same anesthesiologist. The time to intubation and the number of attempts were recorded and related to the Mallampati and Cormack classes. RESULTS: In the first study time of intubation with Trachlight was 20.93 +/- 13.02s (mean +/- SD) without statistical differences in respect to the Mallampati classes. In the second study the times to intubation were without any statistical difference independently of the technique of intubation and of the Mallampati or Cormack classes. CONCLUSIONS: Orotracheal intubation using Trachlight appears to be an effective and easy to learn technique, being also easy, safe and fast to carry out. The comparison with direct laryngoscopy showed the same speed and effectiveness even on patients with difficult intubation.

Adolescent↗
PubMed1995

Relationship between physical activity level and bone mineral density in two groups of female athletes.

In order to evaluate the possible relationships among hormonal status, physical activity and bone density, we carried out a study on two groups of female athletes engaged in different levels of physical activity. We measured the following hormones: luteinizing hormone (LH), folliculo-stimulating hormone (FSH), 17-beta-oestradiol (E2), progesterone (PRG), prolactin (HPRL), estrone (E1), thyreo-stimulating hormone (TSH), free thyroxine (FT4), and the markers of phosphate-calcium metabolism: calcitonine (CT), parathormone (PTH), and osteocalcine (BGP). We also measured bone mineral density (BMD). All of these variables were related to the amount of work performed during training. The groups were defined as follows: medium workload (group M, n = 10) and heavy workload (group H, n = 20), engaged in 10 and 18 hours of weekly training at 35 and 60 average percent of VO2max, respectively. All of the hormones and the markers of calcium-phosphate metabolism studied were normal; BMD was also normal for all subjects except for two sisters in group M with reduced BMD. The group H athletes with regular menstrual cycles were found to have an upper limit normal BMD. From these data we conclude that in regularly menstruating athletes an increase in BMD induced by heavy physical activity is evident, while in dysmenorrhoeic athletes the effect of physical activity compensates, to some extent, for the hypothetical bone mineral reduction possibly caused by the hormonal imbalance.

Aged↗
PubMed1993

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)

Adult↗