Biomedical subjects

A Lucía

Publications and source records attributed to A Lucía.

At least 19 recordsLinked to original sources

PubMed2002

The response of sexual and stress hormones of male pro-cyclists during continuous intense competition.

The aim of this study was to compare hormonal changes in plasma total testosterone (T), cortisol (C), luteinizing hormone (LH), follicle-stimulating hormone (FSH) and prolactin (P) in two world-class teams, both consisting of 9 top male pro-cyclists, during a real sports situation (the 1998 "Vuelta a España", a 3-week multi-stage international cycling competition). Venous blood samples were taken the day before the race (S0), after 1 week (S1), after 2 weeks (S2) and at the end of the race (S3). The S0 T level was significantly lower in the team with more racing days in the previous month. There was a significant basal T decrease (p < 0.05) during the race in comparison with the initial value, in spite of the difference in S0 T level between teams. However, there was no difference between teams in the mean decrease in T level. C decreased significantly between S0 and S1 and between S1 and S2, but not between S2 and S3. There were no differences in P concentration between teams or throughout the study, except for a significant increase between S2 and S3. There were no initial differences in LH nor FSH concentration between the teams, nor at any of the study follow-up times. We conclude that in professional top-level athletes S0 T values depend on the number of competition days of the previous month. We observed a similar decrease in the T levels in both teams, independent of the absolute S0 values. In both teams C decreased during long-lasting cycling competition.

Adaptation, Physiological↗

PubMed2002

Lactic acidosis, potassium, and the heart rate deflection point in professional road cyclists.

OBJECTIVE: To determine the influence of lactic acidosis, the Bohr effect, and exercise induced hyperkalaemia on the occurrence of the heart rate deflection point (HRDP) in elite (professional) cyclists. METHODS: Sixteen professional male road cyclists (mean (SD) age 26 (1) years) performed a ramp test on a cycle ergometer (workload increases of 5 W/12 s, averaging 25 W/min). Heart rate (HR), gas exchange parameters, and blood variables (lactate, pH, P(50) of the oxyhaemoglobin dissociation curve, and K(+)) were measured during the tests. RESULTS: A HRDP was shown in 56% of subjects at about 88% of their maximal HR (HRDP group; n = 9) but was linear in the rest (No-HRDP group; n = 7). In the HRDP group, the slope of the HR-workload regression line above the HRDP correlated inversely with levels of K(+) at the maximal power output (r = -0.67; p<0.05). CONCLUSIONS: The HRDP phenomenon is associated, at least partly, with exercise induced hyperkalaemia.

Acidosis, Lactic↗

PubMed2001

Immunolabelling, histochemistry and in situ hybridisation in human skeletal muscle fibres to detect myosin heavy chain expression at the protein and mRNA level.

The distribution of muscle fibres classified on the basis of their content of different myosin heavy chain (MHC) isoforms was analysed in vastus lateralis muscle biopsies of 15 young men (with an average age of 22 y) by correlating immunohistochemistry with specific anti-MHC monoclonal antibodies, myofibrillar ATPase (mATPase) histochemistry and in situ hybridisation with probes specific for MHC beta-slow, MHC-IIA and MHC-IIX. The characterisation of a large number of individual fibres was compared and correlated on a fibre-to-fibre basis. The panel of monoclonal antibodies used in the study allowed classification of human skeletal muscle fibres into 5 categories according to the MHC isoform they express at the protein level, types I, I+IIA, IIA, IIAX and IIX. Hybrid fibres coexpressing two isoforms represented a considerable proportion of the fibre composition (about 14%) and were clearly underestimated by mATPase histochemistry. For a very high percentage of fibres there was a precise correspondence between the MHC protein isoforms and mRNA transcripts. The integrated methods used demonstrate a high degree of precision of the immunohistochemical procedure used for the identification and quantification of human skeletal muscle fibre types. The monoclonal antibody S5-8H2 is particularly useful for identifying hybrid IIAX fibres. This protocol offers new prospects for muscle fibre classification in human experimental studies.

Adult↗

PubMed2001

Preferred pedalling cadence in professional cycling.

PURPOSE: The aim of this investigation was to evaluate the preferred cycling cadence of professional riders during competition. METHODS: We measured the cadence of seven professional cyclists (28 +/- 1 yr) during 3-wk road races (Giro d'Italia, Tour de France, and Vuelta a España) involving three main competition requirements: uphill cycling (high mountain passes of approximately 15 km, or HM); individual time trials of approximately 50 km on level ground (TT); and flat, long ( approximately 190 km) group stages (F). Heart rate (HR) data were also recorded as an indicator of exercise intensity during HM, TT, and F. RESULTS: Mean cadence was significantly lower (P < 0.01) during HM (71.0 +/- 1.4 rpm) than either F and TT (89.3 +/- 1.0 and 92.4 +/- 1.3 rpm, respectively). HR was similar during HM and TT (157 +/- 4 and 158 +/- 3 bpm) and in both cases higher (P < 0.01) than during F (124 +/- 2 bpm). CONCLUSION: During both F and TT, professional riders spontaneously adopt higher cadences (around 90 rpm) than those previously reported in the majority of laboratory studies as being the most economical. In contrast, during HM they seem to adopt a more economical pedalling rate (approximately 70 rpm), possibly as a result of the specific demands of this competition phase.

Adult↗

PubMed2001

Effects of an endurance cycling competition on resting serum insulin-like growth factor I (IGF-I) and its binding proteins IGFBP-1 and IGFBP-3.

OBJECTIVES: To determine whether consecutive bouts of intense endurance exercise over a three week period alters serum concentrations of insulin-like growth factor I (IGF-I) and/or its binding proteins. METHODS: Seventeen professional cyclists (mean (SEM) VO(2)MAX, 74.7 (2.1) ml/kg/min; age, 27 (1) years) competing in a three week tour race were selected as subjects. Blood samples were collected at each of the following time points: t(0) (control, before the start of competition), t(1) (end of first week), and t(3) (end of third week). Serum levels of both total and free IGF-I and IGF binding proteins 1 and 3 (IGFBP-1 and IGFBP-3) were measured in each of the samples. Cortisol levels were measured in nine subjects. RESULTS: A significant (p<0.01) increase was found in total IGF-I and IGFBP-1 at both t(1) and t(3) compared with t(o) (IGF-I: 110.9 (17.7), 186.8 (12.0), 196.9 (14.7) ng/ml at t(0), t(1), and t(3) respectively; IGFBP-1: 54.6 (6.6), 80.6 (8.0), and 89.2 (7.9) ng/ml at t(0), t(1), and t(3) respectively). A significant (p<0.01) decrease was noted in free IGF-I at t(3) compared with both t(o) and t(1) (t(0): 0.9 (0.1) ng/ml; t(1): 0.9 (0.1) ng/ml; t(3): 0.7 (0.1) ng/ml); in contrast, IGFBP-3 levels remained stable throughout the race. CONCLUSIONS: It would appear that the increase in circulating levels of both IGF-I and its binding protein IGFBP-1 is a short term (one week) endocrine adaptation to endurance exercise. After three weeks of training, total IGF-I and IGFBP-1 remained stable, whereas free IGF-I fell below starting levels.

Adult↗

PubMed2001

Hormone levels of world class cyclists during the Tour of Spain stage race.

OBJECTIVES: To evaluate the hormonal response to strenuous endurance exercise performed by elite athletes. METHODS: Nine professional cyclists (mean (SD) age 28 (1) years; mean (SD) VO(2)MAX 75.3 (2.3) ml/kg/min) who participated in a three week tour race (Vuelta a España 1999) were selected as subjects. Morning urinary levels of 6-sulphatoxymelatonin (aMT6s) and morning serum levels of testosterone, follicle stimulating (FSH), luteinising hormone (LH), and cortisol were measured in each subject at t(0) (before the competition), t(1) (end of first week), t(2) (end of second week), and t(3) (end of third week). Urine samples of aMT6s were also evaluated in the evening at t(0), t(1), t(2), and t(3). RESULTS: Mean urinary aMT6s levels had increased significantly (p<0.01) during the day after each stage (1091 (33) v 683 (68) ng/ml at t(1); 955 (19) v 473 (53) ng/ml at t(2); 647 (61) v 337 (47) ng/ml at t(3)). Both morning and evening aMT6s levels decreased significantly during the study. A similar pattern was observed for morning serum levels of cortisol and testosterone. CONCLUSIONS: The results suggest that the basal activity of the pineal gland, adrenal glands, and testis may be decreased after consecutive days of intense, long term exercise.

Adult↗

PubMed2001

Thyroid hormone levels during a 3-week professional road cycling competition.

AIMS: The aim of this investigation was to examine the thyroid hormone levels of professional cyclists during a 3-week stage competition (Vuelta a España 1998). METHODS: The study population was made up of 16 male cyclists from two world-leading professional teams. Four blood samples were drawn (between 07:00 and 09:00 a.m.) from each participant before and at the end of the 1st, 2nd and 3rd weeks of competition. 3,5,3'(-Triiodothyronine (T(3)), free T(3) (FT(3)), thyroxine (T(4)), free T(4) (FT(4)) and thyroid-stimulating hormone (TSH) were determined in each blood sample by radioimmunoassay. RESULTS: Serum T(4), FT(4) and FT(3) levels showed a significant increase (p < 0.05) by the last week of competition while concentrations of TSH and T(3) remained unchanged. CONCLUSION: In conclusion, 3 weeks of competition provokes changes in basal thyroid hormone concentrations in professional road cyclists.

Adult↗

PubMed2001

Plasma oxytocin during intense exercise in professional cyclists.

AIMS: This study was designed to explore the plasma oxytocin (OT) response to exercise until exhaustion in trained male cyclists. METHODS: Twelve professional cyclists (EXP group; age: 26 +/- 2 years; VO(2)max: 4,804 +/- 549 ml) and 10 sedentary young men (CONT group; age: 23 +/- 2 years; VO(2)max: 3,146 +/- 602 ml) performed a maximal incremental exercise test on a cycle ergometer. Evaluation was made of the oxygen uptake (VO(2)) and concentrations of blood lactate and plasma OT immediately before, during and immediately after the tests, respectively. RESULTS: Significant increases (p < 0.01) related to exercise were recorded in VO(2) and lactate concentration within each group, while no such changes were observed in OT levels. OT values, on the other hand, were significantly lower (p < 0.01) in EXP than in CONT throughout the tests. CONCLUSION: It was concluded that plasma OT shows no response to graded exercise until exhaustion in professional cyclists.

Adult↗

PubMed2001

Effects of endurance training on the breathing pattern of professional cyclists.

The aim of this longitudinal study was to clarify the changes induced by endurance training on the breathing pattern of 13 professional cyclists (age+/-SD: 24+/-2 years; VO(2 max) approximately 75 ml x kg(-1) x min(-1)) during the three periods (rest, precompetition, and competition) of a sports season. Both the volume and the intensity of training were quantified during these periods. In each session (corresponding to each of the three periods) all subjects performed (1) a pulmonary function test (to measure forced vital capacity [FVC], peak expiratory flow [PEF], and maximal voluntary ventilation [MVV]), and (2) a ramp test until exhaustion on a cycle ergometer (workload increases of 25 W x min(-1)). The following variables were recorded every 100 W until the end of the tests: pulmonary ventilation (VE, in l x min(-1) BTPS), tidal volume (VT, inl BTPS), breathing frequency (f(b), in breaths x min(-1)), ventilatory equivalents for oxygen (VE x VO(2)(-1)) and carbon dioxide (VE x VCO(2)(-1)), inspiratory (TI) and expiratory (TE) times (s), ratio of TI to total respiratory duration or inspiratory "duty cycle" (TI/TTOT, and mean inspiratory flow rate (VT)/TI), in l x s(-1)). The results showed no changes in any of these variables (p>0.05) between the three periods of study, despite significant changes in training loads (i.e., increases in the volume and/or intensity of training throughout the season). These findings suggest that endurance conditioning does not alter the breathing pattern of professional cyclists during an incremental exercise test.

Adult↗

PubMed2001

Thyroid hormones may influence the slow component of VO(2) in professional cyclists.

We analyzed the relationship between the plasma concentrations of several hormones (testosterone [T], follicle-stimulating [FSH] and luteinizing hormone [LH], cortisol [C], 3,5,3'-triiodothyronine [T(3)], thyroxine [T(4)], and thyrotrophin [TSH]) and the magnitude of the VO(2) slow component (Delta VO(2)) in a group of nine professional road cyclists (26+/-2 years). The resting levels of the aforementioned hormones were determined before the subjects performed a 20-min cycle ergometer test at approximately 80% of VO(2 max) (or approximately 400 W). Plasma concentrations of T(3) and T(4) were inversely correlated (p<0.05) with Delta VO(2) (r=-0.72 and rr=-0.66, respectively), suggesting, at least partly, and association between thyroid basal function and the VO(2) slow component of euthyroid elite endurance athletes during constant-load intense exercise.

Adult↗

PubMed2001

Caffeine ingestion attenuates the VO(2) slow component during intense exercise.

The purpose of this study was to analyze the effects of caffeine ingestion on the slow component of oxygen uptake (DeltaVO(2)) during high-intensity endurance exercise. Nine subjects (8 male and 1 female; age: 21 +/- 1 years; VO(2 max): 57.9 +/- 1.5 ml kg(-1) min(-1)) performed two 9-min tests on a treadmill at a running velocity eliciting 90% of their VO(2 max), 60 min after ingesting either a placebo capsule (PLAC) or a capsule containing a caffeine dose of 5 mg (kg body mass)(-1) [CAFF]. The mean values of DeltaVO(2) were significantly lower in CAFF than in PLAC (83 +/- 31 ml min(-1) vs. 167 +/- 26 ml min(-1), respectively; p < 0.05). These findings suggest that the ergogenic effect of caffeine in a high-intensity endurance exercise shown in previous research may be partly mediated by a possible attenuation of the VO(2) slow component.

Adult↗

PubMed2000

Physiological response to professional road cycling: climbers vs. time trialists.

The purpose of this study was to identify possible physiological differences between professional cyclists who show best performance in hill climbing ("climbers") and those who excel in time trials ("time trialists"). To this end, professional, top-level climbers (C; n=8; age 26 +/- 1yr; height 176.0 +/- 2.0cm; body mass 63.6 +/- 2.2 kg) and time trialists (TT; n=6; 27 +/- 1yr; height 181.6 +/- 1.7 cm; body mass 72.3 +/- 2.3 kg) were required to perform two laboratory exercise tests on a cycle ergometer: a) a maximal exercise test (ramp protocol) and b) a constant load test of 20-min duration at approximately 80% of VO2max. Capillary blood lactate concentration and several gas exchange variables were measured during the maximal tests while determinations made during the submaximal tests also included: pH and bicarbonate concentration [HCO3-] in venous blood, and electromyographic (EMG) recordings from the vastus lateralis muscle to estimate root mean square voltage (rms-EMG) and mean power frequency (MPF). Both the maximal lactate concentration in capillary blood and VO2max were greater (p<0.05) in C than in TT (6.6 +/- 0.9 mM vs. 5.0 +/- 0.4 mM, respectively, and 78.4 +/- 3.2 ml x kg(-1) x min(-1) vs. 70.5 +/- 2.4 ml x kg(-1) x min(-1), respectively). Higher mean venous blood pH and [HCO3-] (p<0.05), rms-EMG (p<0.01) and MPF (p<0.05 at 10 and 15min of exercise and p < 0.01 at 5 and 20 min) were recorded in C throughout the submaximal tests. Our findings suggest that in top-level professional cyclists, climbing performance is mainly related to physiological factors (VO2max normalized for body mass, anaerobicl buffer capacity, motor unit recruitment) whereas time trialists tend to achieve greater absolute power outputs. It would also seem that other "technical" requirements of the sport (i. e. pedaling efficiency probably related to biomechanical factors etc.) may be associated with successful time trial performance.

Adult↗

PubMed2000

Heart rate and performance parameters in elite cyclists: a longitudinal study.

PURPOSE: This study was designed to evaluate the stability of target heart rate (HR) values corresponding to performance markers such as lactate threshold (LT) and the first and second ventilatory thresholds (VT1, VT2) in a group of 13 professional road cyclists (VO2max, approximately 75.0 mL x kg(-1) x min(-1)) during the course of a complete sports season. METHODS: Each subject performed a progressive exercise test on a bicycle ergometer (ramp protocol with workload increases of 25 W x min(-1)) three times during the season corresponding to the "active" rest (fall: November), precompetition (winter: January), and competition periods (spring: May) to determine HR values at LT, VT1 and VT2. RESULTS: Despite a significant improvement in performance throughout the training season (i.e., increases in the power output eliciting LT, VT1, or VT2), target HR values were overall stable (HR at LT: 154 +/- 3, 152 +/- 3, and 154 +/- 2 beats x min(-1); HR at VT1: 155 +/- 3, 156 +/- 3, and 159 +/- 3 beats x min(-1); and at VT2: 178 +/- 2, 173 +/- 3, and 176 +/- 2 beats x min(-1) during rest, precompetition, and competition periods, respectively). CONCLUSION: A single laboratory testing session at the beginning of the season might be sufficient to adequately prescribe training loads based on HR data in elite endurance athletes such as professional cyclists. This would simplify the testing schedule generally used for this type of athlete.

Adult↗

PubMed2000

The slow component of VO2 in professional cyclists.

OBJECTIVES: To analyse the slow component of oxygen uptake (VO2) in professional cyclists and to determine whether this phenomenon is due to altered neuromuscular activity, as assessed by surface electromyography (EMG). METHODS: The following variables were measured during 20 minute cycle ergometer tests performed at about 80% of VO2MAX in nine professional road cyclists (mean (SD) age 26 (2) years; VO2max 72.6 (2.2) ml/kg/min): heart rate (HR), gas exchange variables (VO2, ventilation (VE), tidal volume (VT), breathing frequency (fb), ventilatory equivalents for oxygen and carbon dioxide (VE/VO2 and VE/VCO2 respectively), respiratory exchange ratio (RER), and end tidal PO2 and PCO2 (PETO2 and PETCO2 respectively)), blood variables (lactate, pH, and [HCO3-]) and EMG data (root mean from square voltage (rms-EMG) and mean power frequency (MPF)) from the vastus lateralis muscle. RESULTS: The mean magnitude of the slow component (from the end of the third minute to the end of exercise) was 130 (0.04) ml in 17 minutes or 7.6 ml/min. Significant increases from three minute to end of exercise values were found for the following variables: VO2 (p<0.01), HR (p<0.01), VE (p<0.05), fb (p<0.01), VE/VO2 (p<0.05), VE/VCO2 (p<0.01), PETO2 (p<0.05), and blood lactate (p<0.05). In contrast, rms-EMG and MPF showed no change (p>0.05) throughout the exercise tests. CONCLUSIONS: A significant but small VO2 slow component was shown in professional cyclists during constant load heavy exercise. The results suggest that the primary origin of the slow component is not neuromuscular factors in these subjects, at least for exercise intensities up to 80% of VO2MAX.

Adult↗

PubMed2000

Effects of endurance training on the isocapnic buffering and hypocapnic hyperventilation phases in professional cyclists.

OBJECTIVES: To evaluate the changes produced in both the isocapnic buffering and hypocapnic hyperventilation (HHV) phases of professional cyclists (n = 11) in response to endurance training, and to compare the results with those of amateur cyclists (n = 11). METHODS: Each professional cyclist performed three laboratory exercise tests to exhaustion during the active rest (autumn: November), precompetition (winter: January), and competition (spring: May) periods of the sports season. Amateur cyclists only performed one exercise test during the competition period. The isocapnic buffering and HHV ranges were calculated during each test and defined as Vo2 and power output (W). RESULTS: No significant differences were found in the isocapnic buffering range in each of the periods of the sports season in professional cyclists. In contrast, there was a significant reduction in the HHV range (expressed in W) during both the competition (p<0.01) and precompetition(p<0.05) periods compared with the rest period. On the other hand, a longer HHV range (p<0.01) was observed in amateur cyclists than in professional cyclists (whether this was expressed in terms of Vo2 or W). CONCLUSIONS: No change is observed in the isocapnic buffering range of professional cyclists throughout a sports season despite a considerable increase in training loads and a significant reduction in HHV range expressed in terms of power output.

Adult↗

PubMed2000

Heart rate response during incremental exercise in master runners.

We analyzed the kinetics of heart rate (HR) response during incremental treadmill exercise in thirteen master runners (62 +/- 1 yr). The HR/running speed (HR/S) relationship showed the existence of a point of downward deflection (HR(d)) in only approximately 31% of the subjects. Resting echocardiographic evaluations showed similar heart dimensions in all of the subjects. In conclusion, HR does not seem to show a curvilinear response (downward deflection) in most aged athletes.

Aged↗

PubMed2000

Metabolic and neuromuscular adaptations to endurance training in professional cyclists: a longitudinal study.

The aim of this longitudinal study was to analyze the changes in several metabolic and neuromuscular variables in response to endurance training during three defined periods of a full sports season (rest, precompetition and competition). The study population was formed by thirteen professional cyclists (age +/- SEM: 24+/-1 years; mean V(O2 max) approximately 74 ml kg(-1) min(-1)). In each testing session, subjects performed a ramp test until exhaustion on a cycle ergometer (workload increases of 25 W min(-1)). The following variables were recorded every 100 W until the tests: oxygen consumption (V(O2) in l min(-1)), respiratory exchange ratio (RER in V(CO2) V(O2)(-1)) and blood lactate, pH and bicarbonate concentration [HCO3(-)]. Surface electromyography (EMG) recordings were also obtained from the vastus lateralis to determine the variables: root mean square voltage (rms-EMG) and mean power frequency (MPF). RER and lactate values both showed a decrease (p<0.05) throughout the season at exercise intensities corresponding to submaximal workloads. In contrast, no significant differences were found in mean pH or [HCO(3-)]. Finally, rms-EMG tended to increase during the season, with significant differences (p<0.05) observed mainly between the competition and rest periods at most workloads. In contrast, precompetition MPF values increased (p<0.05) with respect to resting values at most submaximal workloads but fell (p<0.05) during the competition period. Our findings suggest that endurance conditioning induces the following general adaptations in elite athletes: (1) lower circulating lactate and increased reliance on aerobic metabolism at a given submaximal intensity, and possibly (2) an enhanced recruitment of motor units in active muscles, as suggested by rms-EMG data.

Adaptation, Physiological↗

PubMed1999

Breathing pattern in highly competitive cyclists during incremental exercise.

The purpose of our investigation was to analyse the breathing patterns of professional cyclists during incremental exercise from submaximal to maximal intensities. A group of 11 elite amateur male road cyclists [E, mean age 23 (SD 2) years, peak oxygen uptake (VO2peak) 73.8 (SD 5.0) ml kg(-1) min(-1)] and 14 professional male road cyclists [P, mean age 26 (SD 2) years, (VO2peak) 73.2 (SD 6.6) ml kg(-1) min(-1)] participated in this study. Each of the subjects performed an exercise test on a cycle ergometer following a ramp protocol (exercise intensity increases of 25 W x min(-1)) until the subject was exhausted. For each subject, the following parameters were recorded during the tests: oxygen consumption (VO2), carbon dioxide output (VCO2), pulmonary ventilation (VE), tidal volume (VT), breathing frequency (fb), ventilatory equivalents for oxygen (VE x VO2(-1)) and carbon dioxide (VE x VCO2(-1)), end-tidal partial pressure of oxygen and partial pressure of carbon dioxide, inspiratory (tI) and expiratory (tE) times, inspiratory duty cycle (tI/tTOT, where tTOT is the time for one respiratory cycle), and mean inspiratory flow rate (VT/tI). Mean values of VE were significantly higher in E at 300, 350 and 400 W (P < 0.05, P < 0.05 and P < 0.01, respectively); fb was also higher in E in most moderate-to-maximal intensities. On the other hand, VT showed a different pattern in both groups at near-to maximal intensities, since no plateau was observed in P. The response of tI and tE was also different. Finally, VT/tI and tI/tTOT showed a similar response in both P and E. It was concluded that the breathing pattern of the two groups differed mainly in two aspects: in the professional cyclists, VE increased at any exercise intensity as a result of increases in both VT and fb, with no evidence of tachypnoeic shift, and tE was prolonged in this group at high exercise intensities. In contrast, neither the central drive nor the timing component of respiration seem to have been significantly altered by the training demands of professional cycling.

Adult↗