POWERbreathe® Inspiratory Muscle Training in Amyotrophic Lateral Sclerosis.

Inspiratory muscle training may benefit respiratory function, cardiocirculatory parameters, quality of life and functionality in neuromuscular diseases. This pilot study aimed to demonstrate the POWERbreathe® inspiratory muscle training effects on maximum inspiratory pressure (PImax), heart rate (HR) and HR variability, as well as the quality of life impairment and functionality in patients with Amyotrophic Lateral Sclerosis (ALS). A pilot single-blinded, non-randomized controlled clinical trial was carried out. A total of 20T ALS patients were enrolled and divided into experimental (n = 10) and control (n = 10) groups. The experimental group received POWERbreathe® inspiratory muscle training in conjunction with usual care, and the control group received only usual care for 8 weeks. PImax (measured by POWERbreathe® KH1), HR and HR variability (evaluated by Polar H7), quality of life impairment [measured by the Amyotrophic Lateral Sclerosis Assessment Questionnaire­40 items (ALSAQ-40)] and functionality [assessed by the ALS Functional Rating Scale Revised (ALSFRS-R)] were collected at baseline and after 8 weeks of intervention. We detected statistically significant differences (p < 0.05) with an effect size ranging from medium to large (Cohen's d = 0.72−1.37); relative to the control group, the experimental group had an increased PImax (mean difference = 10.80 cm H2O; 95% CI = 3.42−18.17) and ALSFRS-R score (mean difference = 5.30 points; 95% CI = −0.03−10.63) and reduced HR (mean difference = −8.80 beats-per-minute; 95% CI = −20.27−2.67) and R-R interval (mean difference = 78.30 ms; 95% CI = 2.89−153.70). POWERbreathe® inspiratory muscle training, in addition to usual care, may improve inspiratory strength and heart rate in patients with ALS. These results encourage larger and longer trials investigating potential clinically relevant benefits of inspiratory muscle training to these patients over the disease course.

Effectiveness of Ultrasonography Visual Biofeedback of the Diaphragm in Conjunction with Inspiratory Muscle Training on Muscle Thickness, Respiratory Pressures, Pain, Disability, Quality of Life and Pulmonary Function in Athletes with Non-Specific Low Back Pain: A Randomized Clinical Trial.

Diaphragmatic weakness and thickness reduction have been detected in athletes with lumbopelvic pain (LPP). Strength training of inspiratory muscles may be necessary for athletes with LPP. Inspiratory muscle training (IMT) and visual biofeedback by rehabilitative ultrasound imaging (RUSI) have been proposed as possible interventions. Here, we determine the effectiveness of visual biofeedback by RUSI with a proposed novel thoracic orthotic device to facilitate diaphragmatic contraction in conjunction with high-intensity IMT in athletes with non-specific LPP. A single-blinded, parallel-group, randomized clinical trial was performed (NCT04097873). Of 86 participants assessed for eligibility, 64 athletes with non-specific LPP (39 males and 25 females; mean age, 33.15 ± 7.79 years) were recruited, randomized, analyzed and received diaphragm visual biofeedback by RUSI in conjunction with high-intensity IMT (RUSI+IMT; n = 32) or isolated high-intensity IMT (IMT; n = 32) interventions for 8 weeks. Diaphragmatic thickness during normal breathing, maximum respiratory pressures, pain intensity, pressure pain threshold on lumbar musculature, disability by the Roland−Morris questionnaire, quality of life by the SF-12 questionnaire and spirometry respiratory parameters were assessed at baseline and after the 8-week intervention. There were significant differences (p = 0.015), within a medium effect size (Cohen's d = 0.62) for the forced expiratory volume in 1-s (FEV1), which was increased in the RUSI+IMT intervention group relative to the IMT alone group. Adverse effects were not observed. The rest of the outcomes did not show significant differences (p > 0.05). Diaphragm visual biofeedback by RUSI with the proposed novel thoracic orthotic device in conjunction with high-intensity IMT improved lung function by increasing FEV1 in athletes with non-specific LPP.

Exercise Physiology at "Conversational Level" Is Not Impaired in Healthy Young Subjects Wearing Masks or Respirators.

OBJECTIVE: The aim of this study was to evaluate the effects of the use of both surgical masks and FFP2 respirators on the inspiratory muscle strength, metabolic parameters, heart rate, subjective perceived exertion, and dyspnea perception, before and during 30 min stable load exercise at "conversational level". METHODS: A randomized cross-over study was carried out. Nineteen healthy adults completed 3 conditions (without a mask, with a surgical mask or an FFP2 respirator) during a 30-min steady-state test at the lactate threshold intensity. Inspiratory muscle strength was measured before and after the test, and metabolic parameters, heart rate, subjective perceived exertion, and dyspnea perception were collected at baseline, during, and after the test. RESULTS: There was a significant reduction in inspiratory muscle strength after the 30-min test in all conditions (control: 6.26 mm Hg, p < 0.5; surgical mask: 8.55 mm Hg, p < 0.01; FFP2 respirator: 12.42 mm Hg, p < 0.001), but without significant differences between them (p = 0.283). Data showed a statistically significant effect for time, but did not show a statistically significant interaction between condition and time for heart rate (p = 0.674), oxygen saturation (p = 0.297), blood lactate level (p = 0.991), rating perceived exertion (p = 0.734) and dyspnea (p = 0.532) comparisons. CONCLUSIONS: The present study findings suggested that inspiratory muscle strength and physiological parameters during "conversational level" exercise were not impaired under wearing masks in healthy, nonsmoking young adults.

Inspiratory Muscle Training in Patients with Heart Failure.

BACKGROUND: Prior systematic reviews and meta-analysis addressed that inspiratory muscle training (IMT) improved inspiratory muscle weakness, cardiorespiratory fitness and quality of life similar to conventional exercise training as a first alternative in deconditioned patients with heart failure (HF) lead to a better adaptation to posterior exercise training. The heterogeneity and variability in a wide range of new studies about this topic led to the necessity of an updated and comprehensive narrative review. The present review aimed to analyze and update the most relevant studies about IMT in patients who suffer from HF. METHODS: A narrative review was carried out about IMT in HF patients including 26 experimental studies divided into 21 clinical trials and 5 quasi-experimental studies identified through database searching in PubMed, Cochrane and PEDro. RESULTS: There is enough evidence to state that IMT produces improvements in functional capacity of patients with HF. Nevertheless, there is not enough evidence to support that IMT could improve cardiovascular parameters, blood biomarkers or quality of life in these patients. CONCLUSIONS: Thus, IMT may be recommended to improve functional capacity in patients who suffer from HF; nevertheless, more evidence is needed regarding cardiovascular parameters, biomarkers and quality of life. Furthermore, mortality or HF hospitalization was not evaluated and most studies were not longer than 3 months. According to IMT protocols and study designs heterogeneity and mid-term follow-up, further investigations through high-quality long-term randomized clinical trials should be performed to achieve systematic reviews and meta-analysis to support strong evidence for IMT in HF patients.

Lactate minimum test during incremental running after a submaximal cycling exercise: a novel test with training applications for triathletes.

AIM: The purpose of the present study was to determine whether running speed determined in a lactate minimum test (lactate minimum intensity, LMI) during a treadmill incremental exercise performed just after submaximal cycling corresponds to the speed of a respiratory exchange ratio of 1.00 (RER-1) and, by extension, to the maximal lactate steady state (MLSS) previously obtained in a standard incremental exercise test. METHODS: Eighteen moderately trained triathletes (15 men, 3 women) underwent two exercise sessions 72 h apart in random order: 1) a standard incremental treadmill test to identify the speed corresponding to RER-1, and 2) a submaximal exercise test on a bicycle-ergometer to obtain the LT (lactate threshold) followed by the incremental portion of the lactate minimum test on the treadmill. RESULTS: No significant differences were detected between running speed and heart rate at RER-1 and LMI (14.44±1.24 vs. 14.11±1.36 km·h-1 and 166.38±9.30 vs. 169.55±8.97 beats·min-1, respectively). Moreover, 95% of the differences between the results of the two incremental tests for running speed and heart rate were within the limits of agreement. CONCLUSION: These findings suggest the possibility of obtaining a valid physiological profile of a triathlete using a single test to assess the level of training in both cycling and running.

Impact of a physical activity program on cerebral vasoreactivity in sedentary elderly people.

AIM: The aim of the present study was to determine the effect of a physical activity program on the hemodynamic response of the brain (vasoreactivity) in elderly people. METHODS: Eighteen men and 25 women (aged 62-67 years) were randomly assigned to an experimental (EXP, N.=22, 12 women) and a control (CON, N.=21, 13 women) group. Subjects in EXP group were required to complete a 7-month program based on aerobic training (3-4 sessions/weekd, 50 min/session, 3-4 sessions/week, at 70% maximum heart rate). Transcranial Doppler ultrasound was used to examine the cerebral blood flow response to hypercapnic and hypocapnic stimuli. We also determined blood pressure, total serum cholesterol, HDL and LDL cholesterol, and triglycerides, and conducted an aerobic capacity test (the 2.4-Km walking test). RESULTS.Brain vasomotor reactivity improved in the EXP group, reflected by a higher blood flow velocity in the middle cerebral artery (MCA) in both cerebral hemispheres in response to hypercapnia (induced by breath holding) (P<0.05). Subjects in EXP group also improved the cardiovascular profile aerobic physical condition (P<0.001) in terms of reduced arterial pressure, total cholesterol and triglyceride levels. CONCLUSION: Our findings indicate that cerebral vasoreactivity in elderly may be improved by undertaking an aerobic exercise program.

Effects of inspiratory muscle training on exercise capacity and spontaneous physical activity in elderly subjects: a randomized controlled pilot trial.

Inspiratory muscle training (IMT) has been shown to improve exercise capacity in diseased populations. We chose to examine the effects of eight weeks of IMT on exercise capacity and spontaneous physical activity in elderly individuals. Eighteen moderately active elderly subjects (68.1 +/- 6.8 years [mean +/- SD]; range 58 - 78 years) were randomly assigned to either an experimental group (n = 9) or a control group (n = 9) in a double-blind manner. All subjects underwent inspiratory muscle testing, treadmill exercise testing and a four-day measurement period of spontaneous physical activity (using accelerometry) both pre- and post-intervention. The experimental group underwent eight weeks of incremental IMT using a pressure threshold device, while the control group underwent sham training using identical devices. After IMT training, inspiratory muscle strength (mean + 21.5 cm H (2)O; 95 % CI: 9.3, 33.7; p = 0.002), V.O (2peak) (+ 2.8 ml x min (-1) x kg (-1); 95 % CI: 0.5, 5.2; p = 0.022), time to exhaustion during a fixed workload treadmill test (+ 7.1 min; 95 % CI: 1.8, 2.4; p = 0.013) and time engaged in moderate-to-vigorous physical activity (+ 59 min; 95 % CI: 15, 78; p = 0.008) improved. Except for a decline in moderate-to-vigorous physical activity, no significant changes were seen in the control group. Therefore, IMT may be a useful technique for positively influencing exercise capacity and physical activity in elderly individuals.

Frequency of the VO2max plateau phenomenon in world-class cyclists.

We aimed to determine the frequency of the VO2max plateau phenomenon in top-level male professional road cyclists (n = 38; VO2max [mean +/- SD]: 73.5 +/- 5.5 ml.kg(-1).min(-1)) and in healthy, sedentary male controls (n = 37; VO2max: 42.7 +/- 5.6 ml.kg(-1).min(-1)). All subjects performed a continuous incremental cycle-ergometer test of 1-min workloads until exhaustion. Power output was increased from a starting value of 25 W (cyclists) or 20 W (controls) at the rate of 25 W.min(-1) (cyclists) or 20 W.min(-1) (controls) until volitional exhaustion. We measured gas-exchange and heart rate (HR) throughout the test. Blood concentrations of lactate (BLa) were measured at end-exercise in both groups. We defined maximal exercise exertion as the attainment of a respiratory exchange rate (RER) >or= 1.1; HR > 95 % age-predicted maximum; and BLa > 8 mmo.l(-1). The VO2max plateau phenomenon was defined as an increase in two or more consecutive 1-min mean VO2 values of less than 1.5 ml.kg(-1).min(-1). Most cyclists met our criteria for maximal exercise effort (RER > 1.1, 100 %; 95 % predicted maximal HR [HRmax], 82 %; BLa > 8 mmol.l(-1), 84 %). However, the proportion of cyclists attaining a V.O (2max) plateau was considerably lower, i.e., 47 %. The majority of controls met the criteria for maximal exercise effort (RER > 1.1, 100 %; predicted HRmax, 68 %; BLa > 8 mmol. l(-1), 73 %), but the proportion of these subjects with a VO2max plateau was only 24 % (significantly lower proportion than in cyclists [p < 0.05]). Scientists should consider 1) if typical criteria of attainment of maximal effort are sufficiently stringent, especially in elite endurance athletes; and 2) whether those humans exhibiting the VO2max plateau phenomenon are those who perform an absolute maximum effort or there are additional distinctive features associated with this phenomenon.

Is there an association between ACE and CKMM polymorphisms and cycling performance status during 3-week races?

In this paper, we examine the association between polymorphisms of the angiotensin-converting enzyme (ACE) and muscle-specific creatine kinase (CKMM) genes, and the actual performance status observed in professional cyclists capable of completing a classic tour stage race such as the Giro d'Italia, Tour de France, or Vuelta a España. To accomplish this, we compared the frequencies of the ACE and CKMM genotypes/alleles in 50 top-level Spanish professional cyclists that have completed at least one of these events to 119 sedentary controls, and 27 elite (Olympic-class) Spanish runners. The genetic polymorphism at the CK-MM locus was detected with the NcoI restriction endonuclease. The results of our study showed that the proportion of the DD genotype was higher in cyclists (50.0 %) than in the other two groups (p<0.05), the proportion of the ID genotype was higher in controls (46.2 %) than in the other two groups (p<0.05), and the proportion of the II genotype was higher in runners (40.7 %) than in the other two groups (p<0.05). The proportion of the D allele was higher in both cyclists (65.0 %) and controls (57.6 %) than in runners (46.3 %) (p<0.001), whereas the proportion of the I allele was higher in runners than in the other two groups (p<0.001). No statistical differences were found for CKK-MM- NcoI. We conclude that in top-level professional cyclists capable of completing a classic 3-wk tour race, the frequency distribution of the D allele and the DD genotype seems to be higher than in other endurance athletes such as elite runners (in whom the I allele is especially frequent).

Relation between physical exertion and heart rate variability characteristics in professional cyclists during the Tour of Spain.

BACKGROUND: Continued exposure to prolonged periods of intense exercise may unfavourably alter neuroendocrine, neuromuscular, and cardiovascular function. OBJECTIVE: To examine the relation between quantifiable levels of exertion (TRIMPS) and resting heart rate (HR) and resting supine heart rate variability (HRV) in professional cyclists during a three week stage race. METHOD: Eight professional male cyclists (mean (SEM) age 27 (1) years, body mass 65.5 (2.3) kg, and maximum rate of oxygen consumption (VO(2)max) 75.6 (2.2) ml/kg/min) riding in the 2001 Vuelta a España were examined for resting HR and HRV on the mornings of day 0 (baseline), day 10 (first rest day), and day 17 (second rest day). The rest days followed stages 1-9 and 10-15 respectively. HR was recorded during each race stage, and total HR time was categorised into a modified, three phase TRIMPS schema. These phases were based on standardised physiological laboratory values obtained during previous VO(2)max testing, where HR time in each phase (phase I = light intensity and less than ventilatory threshold (VT; approximately 70% VO(2)max); phase II = moderate intensity between VT and respiratory compensation point (RCP; approximately 90% VO(2)max); phase III = high intensity (>RCP)) was multiplied by exertional factors of 1, 2, and 3 respectively. RESULTS: Multivariate analysis of variance showed that total TRIMPS for race stages 1-9 (2466 (90)) were greater than for stages 10-15 (2055 (65)) (p<0.0002). However, TRIMPS/day were less for stages 1-9 (274 (10)) than for stages 10-15 (343 (11)) (p<0.01). Despite a trend to decline, no difference in supine resting HR was found between day 0 (53.2 (1.8) beats/min), day 10 (49.0 (2.8) beats/min), and day 17 (48.0 (2.6) beats/min) (p = 0.21). Whereas no significant group mean changes in HR or HRV indices were noted during the course of the race, significant inverse Pearson product-moment correlations were observed between all HRV indices relative to total TRIMPS and TRIMPS/day accumulated in race stages 10-15. Total TRIMPS correlated with square root of mean squared differences of successive RR intervals (r = -0.93; p<0.001), standard deviation of the RR intervals (r = -0.94; p<0.001), log normalised total power (r = -0.97; p<0.001), log normalised low frequency power (r = -0.79; p<0.02), and log normalised high frequency power (r = -0.94; p<0.001). CONCLUSION: HRV may be strongly affected by chronic exposure to heavy exertion. Training volume and intensity are necessary to delineate the degree of these alterations.

Which laboratory variable is related with time trial performance time in the Tour de France?

OBJECTIVE: To investigate the relationship between several physiological variables that can be easily obtained during cycle ergometer gradual testing (for example, peak power output (W(peak)), Vo(2max), or ventilatory threshold (VT)) and actual (>50 km) time trials (TT) time performance during the Tour de France. METHODS: We collected data in professional cyclists from the first TT of the 1998 Tour de France (TT1, 58 km distance; n = 6 cyclists) and the first (TT2, 56.5 km; n = 5) and second TT of the 1999 Tour de France (TT3, 57 km; n = 5). RESULTS: A negative relationship was found between power output (W) at VT (VT(Watt)) and TT final time (s) in TT1 (r = -0.864; p = 0.026; standard error of estimate (SEE) of 73 s; and 95% confidence limits (95% CL) -0.98; -0.18), TT2 (r = -0.77; p = 0.27; SEE of 139 s; and 95% CL -0.98; 0.35), and TT3 (r = -0.923; p = 0.025; SEE of 94 s; and 95% CL -1.00; -0.22). CONCLUSIONS: Actual performance in long TT during the Tour de France (>50 km distance, performed after at least 1-2 weeks of continuous competition), in which some cumulative fatigue inevitably occurs, is related, at least in part, to the power output that elicits the VT. No other routine physiological variable (for example, Vo(2max) or W(peak)) is related to performance in this type of event.

Mutations in the hereditary haemochromatosis gene HFE in professional endurance athletes.

BACKGROUND: Hereditary haemochromatosis, a disease that affects iron metabolism, progresses with a greater or lesser tendency to induce iron overload, possibly leading to severe organ dysfunction. Most elite endurance athletes take iron supplements during their active sporting life, which could aggravate this condition. OBJECTIVE: To determine the prevalence and discuss potential clinical implications of mutations of HFE (the gene responsible for hereditary haemochromatosis) in endurance athletes. METHODS: Basal concentrations of iron, ferritin, and transferrin and transferrin saturation were determined in the period before competition in 65 highly trained athletes. Possible mutations in the HFE gene were evaluated in each subject by extracting genomic DNA from peripheral blood. The restriction enzymes SnaBI and BclI were used to detect the mutations 845G-->A (C282Y) and 187C-->G (H63D). RESULTS: Our findings indicate a high prevalence of HFE gene mutations in this population (49.2%) compared with sedentary controls (33.5%). No association was detected in the athletes between mutations and blood iron markers. CONCLUSIONS: The findings support the need to assess regularly iron stores in elite endurance athletes.

Giro, Tour, and Vuelta in the same season.

The exercise volume and intensity are reported of a male professional cyclist (age 30; VO2max 75.0 ml/kg/min) who successfully completed the 2001 Giro d'Italia (May), Tour de France (July), and Vuelta a España (September). The total exercise time during the Giro, Tour, and Vuelta was 90 hours 44 minutes (5444 minutes), 88 hours 23 minutes (5303 minutes), and 72 hours 59 minutes (4379 minutes) respectively. Heart rate telemetry during the races allowed the exercise intensity to be classified into three phases: I, below the first ventilatory threshold (VT1); II, between VT1 and the second ventilatory threshold (VT2); III, above VT2. Compared with the Giro and Tour, the lower exercise volume of the Vuelta (about 20% less total time) was compensated for by a considerably lower and higher contribution of phases I and III respectively. As a result, the total load (volume x intensity) in the three races was comparable.

Effects of electrical stimulation on VO2 kinetics and delta efficiency in healthy young men.

OBJECTIVE: To determine the effects of electrical stimulation (ES) on oxygen uptake (VO(2)) kinetics and delta efficiency (DE) during gradual exercise. The hypothesis was that ES would attenuate the VO(2)-workload relation and improve DE. METHODS: Fifteen healthy, untrained men (mean (SD) age 22 (5) years) were selected. Ten were electrostimulated on both quadriceps muscles with a frequency of 45-60 Hz, with 12 seconds of stimulation followed by eight seconds recovery for a total of 30 minutes a day, three days a week for six weeks. The remaining five subjects were assigned to a control group. A standardised exercise test on a cycle ergometer (ramp protocol, workload increases of 20 W/min) was performed by each subject before and after the experimental period. The slope of the VO(2)-power output (W) relation (deltaVO(2)/deltaW) and DE were calculated in each subject at moderate to high intensities (above the ventilatory threshold-that is, from 50-60% to 100% VO(2)max). RESULTS: The mean (SEM) values for deltaVO(2)/deltaW and DE had significantly decreased and increased respectively after the six week ES programme (p<0.05; 9.8 (0.2) v 8.6 (0.5) ml O(2)/W/min respectively and 27.7 (0.9) v 31.5 (1.4)% respectively). CONCLUSIONS: ES could be used as a supplementary tool to improve two of the main determinants of endurance capacity, namely VO(2) kinetics and work efficiency.

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.

Effects of transcutaneous short-term electrical stimulation on M. vastus lateralis characteristics of healthy young men.

Fifteen healthy, untrained male subjects (mean age +/- SD, 22 +/- 5 years) were used to examine the plasticity of myosin heavy chain phenotype, size, oxidative capacity and capillarization of skeletal muscle fibre types with short-term electrical stimulation (ES). Ten subjects were electro-stimulated on both quadriceps muscles with a frequency of 45-60 Hz, with 12 s of stimulation followed by 8 s of recovery for a total of 30 min per day, 3 days per week for 6 weeks. The remaining five subjects served as controls. Two vastus lateralis muscle biopsy samples were removed from each subject before (week 0) and after (week 6) ES training. A standardized exercise test on a cycle ergometer was performed by each subject before and after the experimental period and several indicators of whole-body aerobic capacity were estimated. The so-called electromyographic threshold was also determined during the tests. Muscle biopsy samples were analysed by electrophoresis, immunohistochemistry and quantitative histochemistry. Myosin heavy chain (MHC) composition, muscle fibre type distribution, fibre areas, oxidative capacity and capillaries of each fibre type were estimated. Muscular changes with ES revealed an increase of fibres expressing MHC-IIA, and a decrease of fibres expressing MHC-IIX and MHC-I, as well as an increase of the oxidative capacity and mean number of capillaries of fast-twitch (type II) fibres with minimal muscle fibre hypertrophy. These adaptations seem related to a bi-directional transformation from both MHC isoforms I and IIX towards the MHC-IIA isoform. The aerobic performance and electromyographic variables at the whole-body level were not altered by ES. These results indicate that the particular short-term ES training protocol tested in the present study induces significant adaptations in histochemical and metabolic machineries of human skeletal muscle. The results also offer new perspectives for realistic applications of ES in various clinical situations and sport training.

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.

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.

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.