Relationship between lactate and ammonia thresholds in heart transplant patients.

The purpose of this investigation was to study the relationship between both blood ammonia thresholds (AmT) and lactate thresholds (LT) during dynamic exercise in cardiac transplant patients (CTPs). Eleven male patients who had undergone orthotopic cardiac transplantation (age: 54 +/- 11 years, mean +/- SD; height: 165.1 +/- 6.6 cm; body mass: 78.3 +/- 16.1 kg) participated in this study. Each of them performed a bicycle ergometer test (ramp protocol) until volitional fatigue. During each test, gas exchange parameters and ECG responses were determined continuously. In addition, blood lactate and ammonia concentrations were measured every 2 min for determination of both LT and AmT, respectively. Peak values of oxygen uptake (Vo2), respiratory exchange ratio, ventilation, and heart rate averaged 15.9 +/- 3.03 mL.Kg-1.min-1, 1.02 +/- 0.06, 46.69 +/- 5.69 L.min-1, and 124 +/- 16 beats per minute, respectively. However, blood concentrations of lactate and ammonia at peak exercise were 3.7 +/- 0.4 mmol.L-1 and 85.6 +/- 31.7 micrograms.dL-1, respectively. LT and AmT were detected in 8 (72.7% of total) and 9 (81.8% of total) of 11 subjects, respectively. No significant differences were found between mean values of LT and AmT, when both were expressed either as Vo2 (10.01 +/- 1.19 vs 10.5 +/- 2.38 mL.kg-1.min-1, respectively) or as percent Vo2 peak (64.62 +/- 11.362 vs 66.48 +/- 9.19%, respectively). In addition, LT and AmT were significantly correlated (p < 0.05) when both were expressed either as Vo2 (mL.kg-1.min-1) or as percent Vo2 peak (r = 0.70 and r = 0.68, respectively). Our findings suggest that in CTPs, both LT and AmT occur at similar workloads, probably as a result of skeletal muscle alterations associated with chronic deconditioning and immunosuppressive therapy.

Electromyographic response to exercise in cardiac transplant patients: a new method for anaerobic threshold determination?

The purpose of this study was to investigate the possible use of integrated surface electromyography (iEMG) in cardiac transplant patients (CTPs) as a new noninvasive determinant of the metabolic response to exercise by studying the relationship between the iEMG threshold (iEMGT) and other more conventional methods for anaerobic threshold (AT) determination, such as the lactate threshold (LT) and the ventilatory threshold (VT). Thirteen patients (age: 57+/-7 years, mean+/-SD; height: 163+/-7 cm; body mass: 70.5+/-8.6 kg; posttransplant time: 87+/-49 weeks) were selected as subjects. Each of them performed a ramp protocol on a cycle ergometer (starting at 0 W, the workload was increased in 10 W/min). During the tests, gas exchange data, blood lactate levels, and iEMG of the vastus lateralis were collected to determine VT, LT, and iEMGT, respectively. The results evidenced no significant difference between mean values of VT, LT, or iEMGT, when expressed either as oxygen uptake (11.1+/-2.4, 11.7+/-2.3, and 11.0+/-2.8 mL/kg/min, respectively) or as percent maximum oxygen uptake (61.6+/-7.5, 62.2+/-7.7, and 59.6+/-8.2%, respectively). In conclusion, our findings suggest that iEMG might be used as a complementary, noninvasive method for AT determination in CTPs. In addition, since the aerobic impairment of these patients is largely due to peripheral limitation, determination of iEMGT could be used to assess the effectiveness of an exercise rehabilitation program to improve muscle aerobic capacity in CTPs.

Saliva composition and exercise.

Little attention has been directed toward identifying the changes which occur in salivary composition in response to exercise. To address this, our article first refers to the main aspects of salivary gland physiology. A knowledge of the neural control of salivary secretion is especially important for the understanding of the effects of exertion on salivary secretion. Both salivary output and composition depend on the activity of the autonomic nervous system and any modification of this activity can be observed indirectly by alternations in the salivary excretion. The effects of physical activity (with reference to factors such as exercise intensity and duration, or type of exercise protocol) on salivary composition are then considered. Exercise might indeed induce changes in several salivary components such as immunoglobulins, hormones, lactate, proteins and electrolytes. Saliva composition might therefore be used as an alternative noninvasive indicator of the response of the different body tissues and systems to physical exertion. In this respect, the response of salivary amylase and salivary electrolytes to incremental levels of exercise is of particular interest. Beyond a certain intensity of exercise, and coinciding with the accumulation of blood lactate (anaerobic threshold or AT), a 'saliva threshold' (Tsa) does indeed exist. Tsa is the point during exercise at which the levels of salivary alpha-amylase and electrolytes (especially Na+) also begin to rise above baseline levels. The occurrence of the 2 thresholds (AT and Tsa) might, in turn, be attributable to the same underlying mechanism, that of increased adrenal sympathetic activity at high exercise intensities.

Azelastine does not adversely affect aerobic performance.

BACKGROUND: The effect of the treatment of allergic rhinitis with azelastine on physiological indicators of aerobic performance such as VO2 max and ventilatory threshold (VT) were evaluated. The clinical efficacy of azelastine was also established. EXPERIMENTAL DESIGN: fifteen physically active males with allergic rhinitis or rhinoconjunctivitis were selected as subjects (experimental group, EXP). Fifteen physically active, healthy subjects served as controls. Subjects performed a maximal incremental exercise test on a bicycle ergometer (ramp protocol) before and after a 5-day treatment period. During the 5 days, EXP group subjects were treated with azelastine (intranasal dose of 0.56 mg/day). The following variables were recorded before and after treatment: power output (W), HR (beats.min-1), VO2 (ml.kg-1.min-1), minute ventilation (VE, in 1.min-1), and oxygen pulse (VO2.HR-1, in ml.beat -1). Blood lactate concentrations (mmol.l-1) were also determined using capillary blood samples (25 microliters). RESULTS: No significant difference was found between pre- and post-trial variables in control subjects. However, peak HR values were lower in EXP subjects after treatment with azelastine (190 +/- 6 beats.min-1 pre-treatment vs 186 +/- 56 beats.min-1 post-treatment; p < 0.05). In addition, VE values at the exercise intensity corresponding to VT were higher in EXP after treatment (54.7 +/- 12.8 l.min-1 pre-treatment vs 60.2 +/- 14.6 l.min-1 post-treatment, p < 0.05). CONCLUSIONS: These findings suggest that the intranasal administration of azelastine used for the treatment of allergic symptoms of the upper respiratory tract in physically active subjects, does not seem to adversely affect maximal aerobic capacity or submaximal aerobic performance.

Lactic threshold vs ventilatory threshold during a ramp test on a cycle ergometer.

OBJECTIVE: The purpose of this investigation was to study the relationship between the lactate (LT) and the ventilatory threshold (VT) during a ramp protocol in cycle ergometry. PARTICIPANTS: Thirty nine trained male subjects were selected as subjects. EXPERIMENTAL DESIGN: All the subjects performed a maximal ergometric test on a cycle ergometer consisting of a ramp protocol (increases of 25 W.min-1). The anaerobic threshold (AT) was determined using both ventilatory gas analysis (VT) and lactate measurement (LT). All the data related to the VT and LT were expressed in work rate (W), VO2 (ml.kg-1.min-1) and heart rate (bpm) and expressed as mean and standard deviation. Lactate threshold (LT) and ventilatory threshold (VT) were compared using the Student's "t"-test for paired data. Correlation coefficients between both variables were also calculated. Statistical significance was accepted at the 5% level. RESULTS: Results showed significant differences (p < 0.05) between mean values of VT and LT when both expressed either as heart rate (bpm), work rate (W), or VO2 (ml.kg-1.min-1). CONCLUSIONS: It was concluded that LT and VT occur at different exercise intensities during ramp protocol exercise on a cycle ergometer.

The use of a fixed value of RPE during a ramp protocol. Comparison with the ventilatory threshold.

BACKGROUND: The purpose of our investigation was to assess the use of a fixed value (12-13) of the Rating of Perceived Exertion (RPE) scale (6-20) as a valid method for the determination of the workload corresponding to the ventilatory threshold (VT) during a ramp protocol on a cycle ergometer. METHODS: Eleven trained cyclists (22 +/- 3 years of age; VO2max: 65.2 +/- 12.4 ml.kg-1.min-1) were selected as subjects. DESIGN: Each of the subjects performed a ramp protocol on a cycle ergometer (starting at 25 W, with increases of 25 W.min-1 until exhaustion). Gas exchange data were analysed continually during the test to detect the ventilatory threshold (VT) of the subjects. In addition values of RPE were obtained from each subject in the last 15 sec of each 2-minute-interval during the tests, and immediately after exhaustion. The RPE threshold (RPET) was defined as a constant value of 12-13. Mean values of VT and RPET were expressed as VO2 (ml.kg-1.min-1), %VO2max, heart rate (bpm) and power output (W), and were compared using a paired "t"-test. RESULTS: No significant difference (p < 0.05) was found between mean values of VT and RPET, when both parameters where expressed either as VO2, %VO2max, heart rate, or power output. CONCLUSIONS: In conclusion, a fixed value (12-13) of the RPE scale might be used to detect the exercise intensity corresponding to VT. Such parameter may therefore be used for exercise prescription in substitution to more sophisticated methodologies.

Overtraining parameters in special military units.

BACKGROUND: Previous studies have shown the diagnostic relevance of the so-called free testosterone/cortisol ratio (FTCR). A condition of overtraining might indeed exist in an athlete when at least one of the two following criteria are observed: a) a FTCR value lower than 0.00035 (FT in nmol x L(-1) and C in micromol x L(-1)); and b) a decrease in the FTCR of 30% or more. On the other hand, no previous research has studied the incidence of overtraining in special military units as a result of their demanding training programs. HYPOTHESIS: A percentage of recruits of the Spanish special military Unit, "Grupo de Operaciones Especiales," (GOES) might be overtrained. It was the purpose of our study to analyze the effects on the FTCR of an intense physical training program performed by recruits of the GOES. METHODS: Before (PRE) and after (POST) an 8-wk training program, respectively, the following measurements were made in 42 recruits of the GOES: hematological and hormonal parameters (FTCR), aerobic and anaerobic tests, and strength and power tests. RESULTS: A high incidence (10 subjects, 23.8% of total) of overtraining existed among conscripts, as determined by the absolute criterium of a decline in the FCTR of 30% or more when comparing PRE and POST values. Additionally, overtraining was associated with a decrease in performance (i.e., isometric strength, vertical jump, Wingate tests). CONCLUSIONS: In addition to some conventional measurements of performance, the FTCR might be used to monitor exercise training in military units, in order to prevent overtraining.

Anaerobic threshold in children: determination from saliva analysis in field tests.

The purpose of this study was to determine the anaerobic threshold of children by the analysis of saliva collected during field tests. A group of 25 children (mean age, 10.5 years) performed an incremental exercise test on a track, consisting of 4-min stages at increasing running velocities. Before each test (at rest) and at the end of each stage, both blood (via finger pricks) and saliva samples (for measurement of salivary concentrations of Na+ and Cl-) were collected to determine lactate threshold (Thla-) and saliva threshold (Thsa), respectively. There were no significant differences between values of Thla- and Thsa when expressed either as running velocity [mean Thla-, 10.73 (SD 1.96) km.h-1; mean Thsa, 10.89 (SD 1.69) km.h-1)] or heart rate [Thla-, 182(SD 14) beats. min-1 Thsa 183 (SD 11) beats.min-1]. In addition, correlations between Thsa and Thla were high, when both values were expressed as running velocity in kilometres per hour (r = 0.89; P < 0.001), or heart rate in beats per minute (r = 0.90; p < 0.001). In conclusion, these findings suggested that saliva analysis would be a valid method for anaerobic threshold determination in field tests.

Anaerobic threshold determination with analysis of salivary amylase.

The purpose of this study was to determine the anaerobic threshold from analysis of amylase concentration in total saliva during a laboratory exercise test. Each of 20 healthy young men performed both a submaximal and a maximal test on a treadmill. During the submaximal test, capillary blood and total saliva samples were collected for determination of anaerobic threshold (AT) and saliva threshold (Tsa), respectively. Tsa was defined as the point at which the first continuous increase in amylase concentration occurred during exercise. The results showed no significant difference between values of AT and Tsa when both were expressed either as running velocity or as heart rate. In addition, there existed a high correlation between AT and Tsa (r = .93, p < .001). It was therefore concluded that the analysis of amylase concentration in total saliva during exercise might be used as a valid new method for determining AT.

Effects of muscle electrical stimulation on peak VO2 in cardiac transplant patients.

Peak oxygen consumption (peak VO2) has become a critical component in the evaluation of heart transplant recipients (HTR). In these patients, peak VO2 remains low after cardiac transplantation mainly because of persisting peripheral limitations in the working muscles. Muscular electrical stimulation, on the other hand, has been shown to enhance the oxidative capacity of healthy muscle. It was the purpose of our investigation to study the effects of ES on the peak VO2 of HTR. Fourteen (11 males and 3 females) HTR (age: 57+/-7yr, mean +/- SD; height: 163+/-7 cm, weight: 70.5+/-8.6 kg) were selected as subjects and each of them was randomly assigned to one of two groups: (a) group EXP (n = 7), receiving electrical stimulation on both quadriceps muscles during a period of 8 weeks, and (b) group CONT (n = 7), not receiving electrical stimulation. Before (PRE) and after (POST) the aforementioned 8-week period, respectively, all the subjects performed a cardiopulmonary exercise test (ramp protocol) on a cycle ergometer for peak VO2 determination. PRE values of peak VO2 were similar in both groups (17.1+/-2.0 vs 16.9+/-3.8ml x kg(-1) x min(-1) in EXP and CONT, respectively). However, peak values of VO2 significantly increased in EXP (p < 0.05) after the period of electrical stimulation (POST peak VO2: 18.7+/-2.0ml x kg(-1)), whereas no change was observed in CONT (POST peak VO2: 16.2+/-3.2 ml x kg(-1) x min(-1)). In conclusion, electrical stimulation could therefore be used to improve the functional capacity of HTR, and might be included in the rehabilitation programs of this population group.