Recovery of cardiorespiratory system indicators in athletes after performing physical load

This study examined ethnic differences in blood pressure and pulse rate in young adults to see whether the differences, if they exist, can be explained by differences in body mass index, lifestyle, psychological, and socioeconomic characteristics. Data used were from the baseline examination of the Coronary Artery Risk Development in (Young) Adults Study (CARDIA). CARDIA is a longitudinal study of lifestyle and evolution of cardiovascular disease risk factors in 5,116 young adults, black and white, men and women, aged 18-30 years, of varying socioeconomic status. Young black adults had higher mean systolic blood pressure and slightly higher mean diastolic blood pressure than young white adults. For both men and women, the blood pressure differences between blacks and whites tended to be greater for the age group 25-30 than for the age group 18-24 years. Among the variables studied, body mass index, duration of exercise on the treadmill, number of cigarettes smoked per day, and number of alcoholic drinks per week were consistently associated with blood pressure. The blood pressure differences were greatly reduced after adjusting for these variables. Black participants had lower mean pulse rate than white participants. The differences tended to be greater for the age group 18-24 than for the age group 25-30 years. Among the variables studied, only duration on treadmill and number of cigarettes smoked per day were consistently correlated with pulse rate. With adjustment for duration on treadmill, the differences in pulse rate increased. These results suggest that differences in ethnic pattern of blood pressures and pulse rate with age may be due in part to obesity, physical fitness, alcohol consumption, and cigarette smoking.

To evaluate differences in pulse rate, rectal temperature, respiratory rate, and systolic arterial blood pressure in dogs between the home and veterinary hospital environments. Prospective observational study. 30 client-owned healthy dogs. Study dogs had respiratory rate, pulse rate, rectal temperature, and systolic arterial blood pressure measured in their home environment. Dogs were then transported to the veterinary hospital, and measurements were repeated. Significant differences in blood pressure, rectal temperature, and pulse rate were observed between measurements obtained in the home and hospital environments. Mean blood pressure increased by 16% (95% confidence interval [CI], 8.8% to 24%), rectal temperature increased by < 1% (95% CI, 0.1% to 0.6%), and pulse rate increased by 11% (95% CI, 5.3% to 17.6%). The number of dogs panting in the hospital environment (19/30 [63%]) was significantly higher than the number of dogs panting in the home environment (5/30 [17%]) Results of the present study suggested that practitioners should consider stress from transportation and environmental change when canine patients have abnormalities of vital signs on initial examination, and the variables in question should be rechecked before a definitive diagnosis of medical illness is reached or extensive further workup is pursued.

PURPOSE: An attenuated heart rate recovery (HRR) 1 minute after maximal exercise is an independent predictor of sudden cardiac death and is associated with all-cause mortality in general populations. The association between sympathetic neural activity (SNA) and HRR is not known. We hypothesized that high SNA is associated with low HRR. METHODS: HRR was measured 1 minute after maximal exercise test for 16 healthy male subjects (age 33±5 years). In a separate session, the sympathetic and vagal activities were analysed at rest, during an incremental arm-ergometer exercise at the levels of 20, 40, 60 and 80 W and during recovery phase. SNA was measured directly from the peroneus nerve by microelectrode technique and vagal activity from beat-to-beat R-R interval variability from Poincaré plots (SD1). RESULTS: SNA increased linearly during exercise and was significantly higher than baseline after exercise e.g 14±6 bursts/min at rest, 38±13 bursts/min at the level of 80 W and 31±7 bursts/min during the first minute of recovery (p<0.001 for both compared with baseline). Cardiac vagal index (SD1) deceased linearly during exercise, e.g. 38±15 ms at rest and 5±2 ms at the level of 80 W (p<0.001). However, SD1 increased rapidly back to the baseline after exercise, e.g. 37±21 ms for the first minute of recovery (p=ns compared with baseline). HRR was strongly correlated with SNA at rest (r=−0.54, p=0.016), during exercise (r=−0.62, p=0.005 for 80 W) and during the recovery phase (r=−0.45, p=0.039 for the firsts minute of recovery). Cardiac vagal index or heart rate did not correlate with HRR at any phases of intervention. CONCLUSIONS: There are several novel findings in the present study. First, SNA increases immediately during exercise even at the very low exercise intensity level and is markedly augmented after exercise. Secondly, SNA is strongly associated with HRR. This association was obvious at rest as well as during and after exercise. An attenuated HRR after exercise is more closely related to sympathetic neural hyperactivity than to cardiac vagal outflow.

Previous studies evaluating heart rate recovery following treadmill test have significant limitations. We evaluated heart rate recovery pattern in ninety five normal individuals of both genders and different age groups after strictly excluding any cardiac or systemic illness. We observed three distinct patterns of heart rate recovery. Some individuals had significant fall in heart rate during the first minute of recovery. Second group had greater reduction in heart rate during second and third minute of recovery. The third group had nearly similar fall in heart rate during first minute of recovery and during next two minute. However all individuals had a reduction of fifty beats per minute or more during initial three minutes of recovery. Subsequently reduction in heart rate was very slow. None of the individuals reached pre-exercise heart rate up to the end of seven minutes of recovery. Our observations will help better planning of future studies trying to correlate significance of heart rate recovery with diagnosis or prognosis.

1. Acoustic communication in the gray treefrog,H. versicolor, was studied by analyzing the vocalizations of males and observing the phonotactic behavior of gravid females in response to pairs of synthetic stimuli, which usually simulated choices between calls of conspecific males at different temperatures or choices between calls of conspecific males and those of a sibling species,H. chrysoscelis. Calls ofH. chrysoscelis were also analyzed acoustically. 2. Pulse duty cycle (pulse duration divided by pulse period) averaged about 0.50 in the calls of both species over a wide range of temperature (Table 1). Pulse rise-time (as a percentage of pulse duration), which was also temperature-independent, was significantly longer inH. versicolor than inH. chrysoscelis (Table 1). The species difference in pulse shape was evident at a distance of 10 m from calling frogs (Fig. 1). 3. Females strongly preferred a linear approximation to the pulse shape (rise-time) typical of conspecific calls to an approximation of the pulse shape typical ofH. chrysoscelis (Figs. 1, 2A). Females did not show a preference between linear and exponential approximations of the conspecific pulse shape (Figs. 1, 2B). 4. When offered choices between synthetic calls that differed in pulse rate (pulses per s=p/s), females were usually very selective, choosing a stimulus with a pulse rate typical of a conspecific male at the test temperature over alternatives that differed by as little as 25% (Figs. 4–6). When both the call rate and pulse rate of synthetic calls were changed (Fig. 3), females showed temperature-dependent reversals in preference between 16 and 24°C (16 p/s vs 25 p/s) and between 16 and 20°C (15 p/s vs 20 p/s), but not between 20 and 24°C (20 p/s vs 25 p/s) (Table 2A–C). 5. When the call rates of alternative stimuli were the same, the pulse rate selectivity of females at 20°C was biased toward stimuli with low pulse rates (Table 2F). Females tested at 16°C rejected strongly alternatives with a high pulse rate, but females tested at 24°C did not reject strongly alternatives with a low pulse rate (Table 2E). Females tested at 24°C were also less selective than females tested at 20°C in rejecting alternatives with a high pulse rate, in the range ofH. chrysoscelis (Table 2D). Females tested at 24°C did, however, strongly reject an alternative with both a pulse rate and pulse shape typical ofH. chrysoscelis (Fig. 6). 6. Call duration and call rate were also relevant properties; changes in these variables modified preferences based on differences in pulse rate, provided that the pulse rates of both alternatives were within the range of variation produced by conspecific males over the normal range of breeding temperatures (Figs. 4–6). 7. Females showed a weak preference for synthetic calls with a bimodal spectral structure typical of conspecific males (1.1 kHz [−6 dB]+2.2 kHz) to a synthetic call with a single spectral component of 2.2 kHz. In tests of single-component stimuli of 1.9 or 2.2 kHz against alternatives of lower and higher frequencies, female preferences indicated a pattern of relative frequency sensitivity (Fig. 7) that was similar to that of an audiogram based on evoked potentials in the midbrain over the same range of frequency. 8. About 50% of the females tested responded phonotactically to a recorded call ofH. chrysoscelis when they had no other choice (Table 3). Thus, heterospecific signals were not only audible, but also behaviorally effective in the context of courtship. 9. Pattern of female preferences with respect to pulse shape and pulse rate suggest that the potential for mismating with males ofH. chrysoscelis has been an important selective force in the evolution of acoustic pattern discrimination inH. versicolor. 10. Results of this study are compared with those of other anurans and acoustic insects. Temperature-dependent shifts in temporal pattern preference, similar but less pronounced than those reported here for both fine temporal and gross temporal properties, were found in some species but not in others. 11. The pulse rate of the male's call increases linearly over a wide range of temperature (9–34°C; Gayou 1984), but female selectivity for pulse rate differs within the range of 16–24°C and is biased toward low pulse rates (Table 2). Thus, it is unlikely that both the temporal patterning of the male's call and temporal pattern recognition by the female are controlled rigidly and linearly by the same neural circuitry. 12. We discuss neurophysiological studies of temporal pattern selectivity in acoustic insects and anurans. There are several neural correlates of behavioral selectivity in gray treefrogs, but no published data concerning a neural correlate of the asymmetry in the strength of pulse rate preferences in gray treefrogs.

Studies on exercise intolerance in persons with chronic obstructive pulmonary disease (COPD) have primarily focused on limitations in ventilation and gas exchange. However, recent studies have suggested that peripheral skeletal muscle is mechanically compromised in this group, and may play an additional role in the inability of persons with COPD to exercise. PURPOSE The purpose of this study was to compare changes in peripheral muscle oxygen utilization in persons with COPD compared to healthy controls. METHODS Eight persons with moderate COPD (68±15 yrs; FEV1 = 1.0±0.3 l/min, 44±11% predicted) and eight healthy age, weight and activity matched controls (69±12 yrs; FEV1 = 1.8±0.6 l/min, 70±12% predicted) performed a submaximal (∼70% of maximal heart rate) graded exercise test (GXT), and a six-minute steady state exercise test at 50% of the workload obtained during the submaximal GXT. Measurements included oxygen uptake (VO2), heart rate (HR), arterial oxygen saturation (SaO2) and peripheral muscle oxygenation (StO2) at rest, during exercise, and recovery. RESULTS Independent t-tests revealed significantly greater workloads for controls at peak (73.8±36.2 vs. 36.9±11.9 watts) and steady state exercise (36.9±18.1 vs. 18.1±6.5 watts) when compared to COPD. Results of a repeated measures ANOVA (group × time) did not reveal any significant differences in StO2 between the groups (Control vs. COPD): at rest (29.5±22.8 vs. 30.4±17.3 %), during peak (29.4±19.4 vs. 26.5±15.9%) and constant load exercise (28.1±12.8 vs. 34.8±23.9%) and during the first (48.0±28.9 vs. 42.6±19.4%) and fifth (46.6±29.1 vs. 44.3±21.7%) minute of recovery from exercise. A significant main effect for group was demonstrated for SaO2 during the submaximal GXT and steady state exercise test. Individuals with COPD demonstrated significantly lower SaO2 values for the GXT at rest (96.8±1.0 vs. 93.5±1.7%) and during the first minute of recovery from exercise (96.0±1.3 vs. 92.8±2.4%). During steady state exercise, SaO2 was significantly higher in control participants at rest (96.3±1.3 vs. 93.6±1.5%), at 3 minutes of exercise (95.8±2.1 vs. 92.9±2.6%) and during the fifth minute of recovery from exercise (96.8±0.7 vs. 94.9±1.0%). Regression analysis was utilized to examine the relationship between measures of pulmonary function (FEV1, FVC, % FEV1/FVC), StO2 and SaO2, however no significant correlations were found. CONCLUSION These results suggest that peripheral skeletal muscle oxygenation is not compromised in individuals with moderate COPD during submaximal aerobic exercise, and that limitations in exercise capacity are most likely a result of muscle disuse and poor lung function.

The objective of this study was to establish differences in vagal reactivation, through heart rate recovery and heart rate variability post exercise, in Brazilian jiu-jitsu wrestlers (BJJW). A total of 18 male athletes were evaluated, ten highly trained (HT) and eight moderately trained (MT), who performed a maximum incremental test. At the end of the exercise, the R-R intervals were recorded during the first minute of recovery. We calculated heart rate recovery (HRR60s), and performed linear and non-linear (standard deviation of instantaneous beat-to-beat R-R interval variability – SD1) analysis of heart rate variability (HRV), using the tachogram of the first minute of recovery divided into four segments of 15 s each (0-15 s, 15-30 s, 30-45 s, 45-60 s). Between HT and MT individuals, there were statistically significant differences in HRR60s (p <0.05) and in the non linear analysis of HRV from SD130-45s (p <0.05) and SD145-60s (p <0.05). The results of this research suggest that heart rate kinetics during the first minute after exercise are related to training level and can be used as an index for autonomic cardiovascular control in BJJW.

Relação entre a frequência cardíaca de recuperação após teste ergométrico e índice de massa corpórea

Relation between heart rate recovery after exercise testing and body mass index

This study aimed to investigate the hydration influence on the autonomic responses of coronary artery disease subjects in the immediate recovery period after a cardiovascular rehabilitation session, in view of the risks of a delayed autonomic recovery for this population. 28 males with coronary artery disease were submitted to: (I) Maximum effort test; (II) Control protocol (CP), composed by initial rest, warm-up, exercise and passive recovery; (III) Hydration protocol (HP) similar to CP, but with rehydration during exercise. The recovery was evaluated through the heart rate (HR) variability, HR recovery and by the rate of perceived exertion and recovery. The main results revealed that the vagal reactivation occurred at the first 30 s of recovery in HP and after the first minute in CP. A better behavior of the HR at the first minute of recovery was observed in HP. The rate of perceived exertion had a significant decrease in the first minute of recovery in HP, while in CP this occurred after the third minute. In conclusion, despite an anticipated vagal reactivation found at HP, these results should be analyzed with caution as there were no significant differences between protocols for all variables and the effect sizes were small.

Background We demonstrated that lower baroreflex sensitivity (BRS) values can identify Long QT Syndrome 1(LQT1) patients at lower risk for life-threatening arrhythmias, suggesting a protective role of “blunted” autonomic responses. However, the complexities of the phenylephrine method to assess BRS have limited its use for risk stratification in clinical practice. Objectives To identify an easily quantifiable marker of reflex vagal activation that might perform as well as BRS in predicting a differential risk for life-threatening arrhythmias in LQT1 patients. Specifically, to test the predictive value of heart rate (HR) recovery during the first minute after cessation of an exercise stress test. Methods In a South African LQT1 founder population segregating KCNQ1-A341V, 44 mutation carriers (MCs) underwent an exercise stress test and a phenylephrine test off-β-blockers. The HR decrease during the first minute of recovery from the peak of exercise (Δ 1min-rec ) was measured and subsequently correlated with BRS values among symptomatic (syncope, cardiac arrest, sudden death) and asymptomatic patients. Results Asymptomatic MCs had a smaller decrease in HR during the first minute of recovery from peak exercise (Δ 1min-rec ) than symptomatic MCs (13±5 vs 19±7 bpm, p&lt; 0.05). A Δ 1min-rec &lt;15 bpm, which corresponds to the first tertile of its distribution, predicted a much lower probability of being symptomatic (OR 0.13, 95%CI 0.028-0.63, p&lt;0.05). The Δ 1min-rec values were significantly correlated with BRS values (r=0.64, p=0.001). Both tests performed similarly and quite accurately in discriminating between MCs with or without cardiac events (AUC 0.77 and 0.80). Conclusions LQT1 patients are at risk for life-threatening arrhythmias especially in association with rapid HR changes in either direction. Blunted autonomic responses, identified by lower values of BRS and - as vagal reflexes are concerned - by smaller HR reductions at the end of exercise, can usefully contribute to their risk stratification in a novel, simple, and inexpensive way.

The two main spectral components of the advertisement calls of two species of North American gray treefrogs (Hyla chrysoscelis and H. versicolor) overlap broadly in frequency, and the frequency of each component matches the sensitivity of one of the two different auditory inner ear organs. The calls of the two species differ in the shape and repetition rate (pulse rate) of sound pulses within trills. Standard synthetic calls with one of these spectral peaks and the pulse rate typical of conspecific calls were tested against synthetic alternatives that had the same spectral peak but a different pulse rate. The results were generalized over a wide range of playback levels. Selectivity based on differences in pulse rate depended on which spectral peak was used in some tests, and greater pulse-rate selectivity was usually observed when the low-frequency rather than the high-frequency peak was used. This effect was more pronounced and occurred over a wider range of playback levels in H. versicolor than in H. chrysoscelis when the pulse rate of the alternative was higher than that of the standard call. In tests at high playback levels with an alternative of 15 pulses s(-1), however, females of H. versicolor showed greater selectivity for the standard call when the high-frequency rather than the low-frequency spectral peak was used. This last result may reflect the different ways in which females of the two species assess trains of pulses, and the broad implications for understanding the underlying auditory mechanisms are discussed.

Abnormal heart rate recovery (HRR) following exercise testing has been shown to be a predictor for adverse cardiovascular events. The actual maximum heart rate (MHR) attained during the exercise test does not however have a distinct significance in traditional HRR assessment. The objective of this study was to investigate the role of MHR in HRR. This prospective study consisted of 164 patients (62% male, mean age 53.7 + or - 11.7 years) who were referred for a symptom-limited standard Bruce Protocol treadmill exercise test, based on clinical indications. The patients were seated immediately at test completion and the heart rate (HR) recorded at one and two minutes postexercise. A normal HRR was defined as a HR drop of 18 beats per minute or more at the end of the first minute of recovery. The HRR profile of patients who reached > or = 85% of their maximum predicted heart rate (MPHR) during peak exercise were then compared to HRR profile of those who could not. One hundred twelve patients (Group A) achieved a MHR > or = 85% of MPHR during peak exercise whereas 52 patients (Group B) did not. Chi-square analysis showed a higher incidence of normal HRR in Group A compared to Group B (p = 0.029). Analysis of variance with repeated measures showed that group A had a greater HRR at the first minute F(1,162)= 6.98, p = <0.01) but not the second minute (F(1,162)=1.83, p = .18) postexercise. There is a relation between the peak heart rate attained during exercise and the subsequent HRR. A low peak heart rate increases the likelihood of a less than normal HRR. Assessment of the entire heart-rate response seems warranted for more thorough risk-stratification.

Social status, physical activity, and coronary proneness

Marfan syndrome patients present important cardiac structural changes, ventricular dysfunction, and electrocardiographic changes. An abnormal heart rate response during or after exercise is an independent predictor of mortality and autonomic dysfunction. The aim of the present study was to compare heart rate recovery and chronotropic response obtained by cardiac reserve in patients with Marfan syndrome subjected to submaximal exercise. A total of 12 patients on β-blocker therapy and 13 off β-blocker therapy were compared with 12 healthy controls. They were subjected to submaximal exercise with lactate measurements. The heart rate recovery was obtained in the first minute of recovery and corrected for cardiac reserve and peak lactate concentration. Peak heart rate (141±16 versus 155±17 versus 174±8 bpm; p=0.001), heart rate reserve (58.7±9.4 versus 67.6±14.3 versus 82.6±4.8 bpm; p=0.001), heart rate recovery (22±6 versus 22±8 versus 34±9 bpm; p=0.001), and heart rate recovery/lactate (3±1 versus 3±1 versus 5±1 bpm/mmol/L; p=0.003) were different between Marfan groups and controls, respectively. All the patients with Marfan syndrome had heart rate recovery values below the mean observed in the control group. The absolute values of heart rate recovery were strongly correlated with the heart rate reserve (r=0.76; p=0.001). Marfan syndrome patients have reduced heart rate recovery and chronotropic deficit after submaximal exercise, and the chronotropic deficit is a strong determinant of heart rate recovery. These changes are suggestive of autonomic dysfunction.