Article

# Resting and Postexercise Cardiac Autonomic Control in Trained Masters Athletes

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## Abstract

This study used measures of heart rate variability during recovery from high-intensity exercise in trained Master athletes to examine postexercise cardiac autonomic regulation. Seven males (mean age 52.1 +/- 3.3 yr; mass 85.1 +/- 18.0 kg) and 6 females (mean age 50.5 +/- 2.9 yr; mass 63.1 +/- 6.0 kg) performed incremental exercise to an intensity that induced a >4.5 mmol capillary blood lactate concentration, followed by incremental exercise to volitional exhaustion (VO2(max)). A 6 min ECG recording before (Pre) and after (Post) exercise was analyzed in the time (mean rr interval, sd rr) and frequency domains (total power, very low frequency [VLF: 0-0.04 Hz], low frequency [LF: 0.04-0.15 Hz], high frequency [HF: 0.15-0.4 Hz]). VO2(max) for males and females was 49.4 +/- 7.1 ml kg(-1) min(-1) and 45.1 +/- 10.1 ml kg(-1) min(-1), respectively. Lower mean rr interval (Pre: 1,048 +/- 128 ms; Post: 730 +/- 78 ms; P < 0.001) and lower sd rr (Pre: 77 +/- 30 ms; Post: 43 +/- 17 ms; P < 0.001) were recorded following exercise, with no differences based on gender. Total power decreased following exercise (Pre: 6,331 +/- 6,119 ms; Post: 1,921 +/- 1,552 ms). When normalized for changes in total power, a decreased HF component (Pre: 34.52 +/- 14.79 n.u.; Post: 18.49 +/- 13.64 n.u.; P < 0.05) with no change in LF component (Pre: 61.00 +/- 18.66 n.u.; Post: 69.63 +/- 23.97 n.u.; P = 0.34) was recorded. No gender differences in HRV in the frequency domain were recorded. Decreased heart rate variability in both time and frequency domains suggested an increased parasympathetic withdrawal during the autonomic control of postexercise tachycardia in trained Master athletes.

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... Thus, recovery to baseline is prudently significant. Decrease in R-R variability intervals, SDNN, NN50, and RMSSD, during endurance races indicates a decreased vagal tone [28][29][30][31] in line with the findings of our study. ...
... Resting HR after each stage of the race in our study remained higher than the baseline values, which are consistent with data obtained from Brown & Brown [29] Barak et al. [30] Picanço et al. [31]. The increased workload, physiological stress on the body, and sympathetic dominance lead to an increased resting heart rate. ...
... The increased workload, physiological stress on the body, and sympathetic dominance lead to an increased resting heart rate. Thus, the resultant relative tachycardia reduced TP, which is in agreement with Brown & Brown [29] Barak et al. [30] and Picanço et al. [31] leading to a significant decrease in HRV across the three days of racing. Low VLF power not only predicts autonomic dysfunction but also indicates an increase in inflammation [19]. ...
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Background The acute and chronic adaptation of endurance athletes’ hearts shows that increased volume of endurance exercise might cause an acute reduction in cardiac function, causing a physiological cascade that leads to the release of cardiac biomarkers specific to cardiomyocyte stress. Heart rate variability (HRV) is a valuable tool used as a physiological measurement to evaluate the autonomic nervous system (ANS). It is frequently used to assess cardiac autonomic regulation, determining a patient’s risk for unfavorable events. This study set out to determine the changes in the ANS by participating in a 3-day mountain bike cycling race in amateur cyclists using HRV as an outcome measure. Methods Sixteen healthy participants (male and female) participating in a 3-day mountain bike cycling race underwent five-minute resting electrocardiography recordings in a supine position 2 days before the race (baseline testing). In addition, HRV measurements were recorded after each race day and 24 h post-race (recovery). Results Time-domain and frequency-domain measures showed significant changes from baseline HRV parameters after each race day (p ≤ 0.05). In addition, our data revealed that the mean heart rate and R–R variability intervals did not return to baseline values after 24 h of recovery. Thus, autonomic nervous system (ANS) alterations may be due to changes in cardiac sympatho-vagal balance. Conclusions The main strength of this study is using HRV as a measuring and screening tool to assess cardiac autonomic activity, whereby the state of the ANS before and after endurance races can be measured. Thus, physicians, athletes, and coaches can determine the stress of endurance races on the ANS and plan recovery strategies. The reasoning is that if the ANS is in a state of sub-optimal function, susceptible amateur athletes might be at risk for a cardiovascular event or maladaptation due to the endurance race.
... In this regard, the measure of the acute cardiovascular response should be considered in adult runners during endurance tests in terms of the early identification of high-risk subjects due to possible abnormalities in the control of HR. So far, limited studies have analyzed the exercise HR profile in master athletes [17,19]. Likewise, a limited number of studies have provided relevant reference values for short-term HRV [11] or have analyzed sex differences [19][20][21]. ...
... So far, limited studies have analyzed the exercise HR profile in master athletes [17,19]. Likewise, a limited number of studies have provided relevant reference values for short-term HRV [11] or have analyzed sex differences [19][20][21]. Therefore, advances in the description of the physiological and cardiovascular characteristics of master athletes are necessary for terms of prevention of adverse events, and performance improvement, as well as to determine the positive or negative effects of regular training on the health of the runner. ...
... Concerning sex, our findings are in general agreement with previous studies in endurance runners, which showed that HR-peak values were similar in both sexes [19,49,50]. Regarding age and the theory of an age-related decrease in maximum HR [51], our data showed a moderate negative inverse correlation between age and HR-peak, which was not influenced by sex. ...
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The aim of this study was to analyze the cardiac autonomic function at rest, at maximum exercise, and in recovery after exercise and to determine sex-specific and age-specific values for resting heart rate (RHR), hear rate (HR)-peak, HR recovery (HRR), and HR variability at rest in master runners. Fifty endurance runners (21 women) participated in this study (43.28 ± 5.25 years). The subjects came from different athletic clubs in Andalusia (Spain), and the testing protocol was performed in-season. A 3-km running test was performed and the cardiovascular response was monitored. Regarding sex, no significant differences were found regarding cardiovascular autonomic function at rest, during exercise, and following maximal exercise, only at rest, the standard deviation of all R-R intervals and low frequency values displayed significantly (p < 0.05) lower scores in women. 46% of athletes showed an RHR < 60 bpm. Additionally, HR-peak showed a significant correlation with age (r = −0.369; p = 0.009) and HRR5min (r = 0.476, p = 0.001). Also, endurance performance was inversely associated with obesity traits and cardiometabolic risk factors. In summary, age, sex, fitness, or anthropometrics characteristics did not show a relevant influence on cardiovascular autonomic modulation in master runners. However, the 3-km performance displayed a significant negative association with several factors of cardiometabolic risk.
... 1,7,14,15,16 For the last two decades high maximal oxygen uptake (VO 2max ) has been associated with better autonomic control of the cardiovascular system in athletes compared to sedentary individuals. 7,10,[17][18][19][20][21] Previous studies also suggest that modulation of HR may be influenced by certain physiological factors such as aging, body fatness and specific types of training including aerobic and anaerobic training 9,17,22-25 . However, the optimal exercise prescription to change measures of HRV in terms of intensity, stimulus mode and duration remains undefined. ...
... However, the optimal exercise prescription to change measures of HRV in terms of intensity, stimulus mode and duration remains undefined. 1,7,16,17,18,22,25,26 Moreover, the fact that endurancetrained individuals have consistently higher HRV than untrained individuals suggests that vigorous training programs are necessary to induce changes in HRV 7,9,13,16,17 . ...
... However, the optimal exercise prescription to change measures of HRV in terms of intensity, stimulus mode and duration remains undefined. 1,7,16,17,18,22,25,26 Moreover, the fact that endurancetrained individuals have consistently higher HRV than untrained individuals suggests that vigorous training programs are necessary to induce changes in HRV 7,9,13,16,17 . ...
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Objective: The aim of this study was to investigate the autonomic cardiac modulation between professional volleyball players (VP) and recreational aerobically trained individuals (RAT). Methods: Twenty-eight men were divided into two groups, (VP; n = 14) and (RAT; n = 14) and each group was subjected to a sub-maximal progressive ramp treadmill test. Cardiac cycle beat to beat (RR) intervals, was obtained through electrocardiogram recording with the test being stopped when the individual reached 85% of their maximum age-predicted heart rate (HR). The heart rate variables were calculated from ECG using MATLAB-based algorithms. Results: At rest, RAT showed lower values of the mean value of RR interval, the root mean square successive difference of all RR intervals (r-MSSD), low frequency (LF) and total power spectral (TP) when compared to V P. No significant difference between groups was noted for high frequency (HF) and index LF/HF. After exercise, no significant differences were measured between groups. Mean values of VO2, VE/VO2, and VE showed no significant difference at rest and post effort. Conclusion: The variables such as frequency, intensity and volume may to interfere the autonomic cardiac modulation and possibly indicating a superior protection against exercise-induced ventricular arrhythmias and lower risk of sudden cardiac deaths.
... [13] A study conducted among trained athletes revealed that the variability of heart rate induced by stress is less among people with a habit of regular strenuous exercise. [15] The paper argued that it was because of the favorable autonomous responses. However, the observation in a few individuals (seven men and six women) did not bring out a significant difference across gender. ...
... However, the observation in a few individuals (seven men and six women) did not bring out a significant difference across gender. [15] Another study on 26 female athletes randomized into two groups based on physical activity had also demonstrated the positive effect of exercise in the cardiovascular profile. [16] The incremental advantage of women on blood pressure due to walking was documented among diabetic patients. ...
... The sample size is large when compared to similar studies conducted among people involved in physical exercise as a part of their profession or career. [15,16] The major weakness of the study is that it did not document the differences in the dietary pattern of study participants that can influence the clinical and biochemical indicators. However, we were not expecting a major difference in dietary pattern of the participants. ...
Article
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Gender differences in the risk of developing non-communicable diseases (NCD) are a matter of debate. The susceptibility of a woman to NCD should be evaluated taking into consideration the social factors that limit the physical activity among women. It will be interesting to note what will happen if women are allowed to take part in physical exercise to the extent of men. To find out the gender difference in the pattern of the clinical and biochemical indices related to NCD in young adults with comparable daily physical activity. This is an institution-based cross-sectional study and the setting was Lekshmibhai National College for Physical Education (LNCPE), Thiruvananthapuram, Kerala, India. The study participants were students who were regularly involved in more than three hours of physical exercise daily at least for the previous one year. The information on socio-demography, anthropometry, and blood pressure was recorded. Blood samples were taken for laboratory examination. Out of 150 students registered, 126 (84%) in the age group of 17 to 25 years who fulfilled the eligibility criteria were studied. Fifty-five (43.7%) of them were women. Systolic blood pressure, fasting blood sugar, and low-density lipoprotein were found significantly lower in women. No significant difference was noted in the case of diastolic blood pressure and total cholesterol. Gender differences exist for NCD risk factors among young adults with comparable physical activity and physical exertion seems to be more protective for females.
... Contudo, após o esforço, verifica-se que a potência total atua predominantemente na banda de LF e, consequentemente, seria um possível indicador de alterações na modulação autonômica total, em vez de alterações somente na modulação vagal.28,29 O LF pode refletir múltiplos mecanismos do controle autonômico cardíaco, tais como: a oscilação dos ramos simpático/parassimpático e a resposta reflexa dos barorreceptores cardíacos.30 Contudo, em relação aos resultados deste estudo, especula-se que, em repouso, o aumento do LF em atletas possa estar relacionado às oscilações da atividade cardiovagal presente nas flutuações dos intervalos RR atuante na banda de LF.31 Assim, corroborando estes resultados, Furlan et al.32 comentam que atletas apresentam bradicardia e aumento do componente de LF em repouso. ...
... Contudo, em relação aos resultados deste estudo, especula-se que, em repouso, o aumento do LF em atletas possa estar relacionado às oscilações da atividade cardiovagal presente nas flutuações dos intervalos RR atuante na banda de LF.31 Assim, corroborando estes resultados, Furlan et al.32 comentam que atletas apresentam bradicardia e aumento do componente de LF em repouso. Outro fator que poderia também influenciar a elevação significativa do componente LF nos atletas seria a frequência respiratória que, uma vez atingindo a frequência de 9 ciclos respiratórios/ min, passa a atuar na zona de LF (0,04Hz a 0,15Hz).30 Entretanto, os indivíduos mantiveram a variação dos intervalos respiratórios na faixa de 12 a 18 ciclos respiratórios/min, manifestando sua atividade na zona de HF (0,2Hz a 0,3Hz).30 ...
... Outro fator que poderia também influenciar a elevação significativa do componente LF nos atletas seria a frequência respiratória que, uma vez atingindo a frequência de 9 ciclos respiratórios/ min, passa a atuar na zona de LF (0,04Hz a 0,15Hz).30 Entretanto, os indivíduos mantiveram a variação dos intervalos respiratórios na faixa de 12 a 18 ciclos respiratórios/min, manifestando sua atividade na zona de HF (0,2Hz a 0,3Hz).30 Como fator de limitação do estudo, entende-se que seria necessária, para melhor elucidação dos resultados apresentados, a utilização de um protocolo de teste de esforço máximo, crucial para a verificação dos limiares anaeróbios e determinação do consumo máximo de oxigênio. ...
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Background: During progressive exercise, decreased heart rate variability (HRV) is described, with post- exercise HRV behavior seeming to depend on variables such as duration, type and intensity of the stimulus. Objective: To investigate and compare autonomic c a r d i a c m o d u l a t i o n i n a t h l e t e s a n d t r a i n e d individuals. Methods: Fourteen healthy male: athletes were divided into two groups: Athletes (AT) (n=7; 24.5±7.6 years; 76.2±9.2kg; 24.5±5.5kg/m²) and Trained (TR) (n=7; 26.5±5.2 years; 79.6±26.9kg; 23.45±6.6kg/m²) and were subjected to sub-maximum progressive ramp testing on treadmills. The RR intervals were obtained through a heart monitor (Polar RS800G3), interrupting the test when the individual reached 85% of maximum age-predicted heart rate. In order to analyze the HRV, the RR intervals were used for the 10-minute periods before and after exercise. In the time domain, the following indexes were obtained: RRmean, pNN50 and RMSSD; in the frequency domain, low and high frequency spectrum capacities were obtained (LF: 0.04Hz to 0.15Hz), and (HF: 0.15Hz to 0.4Hz), in addition to the LF/HF ratio and total capacity (TC). Results: The two-way ANOVA followed by a post-hoc Bonferroni test showed significantly higher at-rest values for the AT group compared to the TR group for RRmean (22%; p
... Moreover, in agreement with others, 34,35 we found aerobic conditioning to be more pronounced after HI compared with LI training, that is, HI induced a more pronounced reduction in HR and a more pronounced increase in VO 2peak during the exercise test compared with LI training. The current results show an elevated HR during the first 45 min of recovery compared with pre-exercise rest values, which is consistent with previous data, [36][37][38] but in contrast to Perini et al. 18 With regard to the spectral components of HRV, we observed that the relative LF component in the recovery period was not different from pre-exercise rest values, [37][38][39] whereas the HF component during the recovery period was slightly lower than control. 37, 38 We have not assessed HRV during exercise, but in an earlier study 40 in which we measured HRV during submaximal exercise (up to 40% of maximal workload), we found a slight increase of the relative LF component from 34 to 41%, and a pronounced decrease in the relative HF component from 32 to 9%. ...
... Moreover, in agreement with others, 34,35 we found aerobic conditioning to be more pronounced after HI compared with LI training, that is, HI induced a more pronounced reduction in HR and a more pronounced increase in VO 2peak during the exercise test compared with LI training. The current results show an elevated HR during the first 45 min of recovery compared with pre-exercise rest values, which is consistent with previous data, [36][37][38] but in contrast to Perini et al. 18 With regard to the spectral components of HRV, we observed that the relative LF component in the recovery period was not different from pre-exercise rest values, [37][38][39] whereas the HF component during the recovery period was slightly lower than control. 37, 38 We have not assessed HRV during exercise, but in an earlier study 40 in which we measured HRV during submaximal exercise (up to 40% of maximal workload), we found a slight increase of the relative LF component from 34 to 41%, and a pronounced decrease in the relative HF component from 32 to 9%. ...
... The slightly reduced HF component recorded post-exercise in comparison with the pre-exercise stage may indicate that parasympathetic withdrawal contributes to autonomic control of the post-exercise tachycardia. 37,39 However, it is likely that other phenomena played a more important role, such as the higher body temperature and stimulation of circulating catecholamines. 41,42 Cross-sectional data showed that endurancetrained participants exhibit a more rapid HR recovery than their untrained counterparts after exercise at similar relative work loads. ...
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We aimed to investigate the effects of endurance training intensity (1) on systolic blood pressure (SBP) and heart rate (HR) at rest before exercise, and during and after a maximal exercise test; and (2) on measures of HR variability at rest before exercise and during recovery from the exercise test, in at least 55-year-old healthy sedentary men and women. A randomized crossover study comprising three 10-week periods was performed. In the first and third period, participants exercised at lower or higher intensity (33% or 66% of HR reserve) in random order, with a sedentary period in between. Training programmes were identical except for intensity, and were performed under supervision thrice for 1 h per week. The results show that in the three conditions, that is, at rest before exercise, during exercise and during recovery, we found endurance training at lower and higher intensity to reduce SBP significantly (P<0.05) and to a similar extent. Further, SBP during recovery was, on average, not lower than at rest before exercise, and chronic endurance training did not affect the response of SBP after an acute bout of exercise. The effect of training on HR at rest, during exercise and recovery was more pronounced (P<0.05) with higher intensity. Finally, endurance training had no significant effect on sympathovagal balance. In conclusion, in participants at higher age, both training programmes exert similar effects on SBP at rest, during exercise and during post-exercise recovery, whereas the effects on HR are more pronounced after higher intensity training.
... HR recovery after exercise is influenced by parasympathetic reactivation and sympathetic recovery at resting levels and is an important indicator of sympathetic/parasympathetic balance (Buchheit et al., 2007;Coote, 2010;Duarte et al., 2015;Kingsley & Figueroa, 2016). In turn also using different components of heart rate variability (time and frequency domain) has been confirmed the parasympathetic reactivation after exercise with a significant reduction in the HF power by several studies (Brown & Brown, 2007;Goldberger, 2006;Hautala et al., 2001;Kaikkonen et al., 2007;Martinmäki & Rusko, 2007). In addition, it is currently is a method used by trainers of evaluating acute and chronical effects of different types of training and prevent overtraining (Buchheit et al., 2010;Plews, 2013;Plews et al., 2013;Seiler et al., 2007). ...
... Comparisons between untrained subjects and highly trained endurance athletes have showed that heart rate falls more quickly after a bout of high-intensity exercise in the trained persons (Bellenger et al., 2016;Borresen & Lambert, 2008;Brown & Brown, 2007;Danieli et al., 2014), and as expected, in our results, the response of HR recovery was increasing directly proportional to the passing of the minutes after the end of the exercise in both groups and was lowest in UR group that PES group specially in 17 minutes (Table 2 and Figure II -B). ...
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... It is not novelty that chronic and regular exercise training has positive effects on autonomic nervous system increasing HRV [26][27][28][29][30][31][32][33]. Elite and master endurance athletes seem to have better autonomic function which is represented by elevated parasympathetic heart modulation than their untrained counterparts [27,34]. ...
... Some previous findings in elite young athletes suggested a better autonomic balance of endurance athletes in comparison to sprinters [38]. In spite of the beneficial effects of lifelong endurance training had been widely demonstrated [27][28][29][30][31][32][33], there are few reports regarding the health profile of middle-aged athletes who have a life history of high-intensity training in speed and power, such as master sprinters [36]. ...
Article
Background Aging is associated with decreased autonomic balance which could be assessed by Heart Rate Variability (HRV). Exercise training improves autonomic balance, but there is a lack in the literature regarding the heart rate variability (HRV) of master sprinters and endurance athletes. Purpose The effects of lifelong endurance and sprint training on cardiac autonomic balance were assessed in master athletes and compared with age-matched controls and young untrained controls. Methods Participants (n = 81) were 8 master sprinters (MS; 51.8 ± 11.1 yrs), 8 master endurance athletes (EN, n = 8, 53.6 ± 8.6 yrs), 17 age-matched untrained (CON, 47.47 ± 6.00 yrs) and 48 young controls (YC, 25.40 ± 3.87 yrs). For the acquisition of RR intervals (iRR) (Polar RS800X Heart Rate Monitor®) the participants remained seated for 15-min with the final 10-min being considered for analysis. HRV was measured using Kubios software. A one-way ANOVA with repeated measures was applied. Results All studied parameters did not differ between MS and EN {Time Domain [HR (bpm) 59.00 ± 6.13 vs. 58.94 ± 12.75], [R-R (ms) 1030.45 ± 107.45 vs. 1068.77 ± 206.17], [SDNN (ms) 57.35 ± 20.07 vs. 80.66 ± 71.07], [RMSSD (ms) 40.88 ± 20.07 vs. 38.93 ± 20.44]; Non-linear domain [SD1 (ms) 28.93 ± 14.20 vs. 27.56 ± 14.46]}, whose demonstrated a reduced HR and elevated mean R-R intervals in comparison to both YC {[HR (bpm) 69.64 ± 9.81]; [R-R (ms) 883.93 ± 124.11]} and age-matched controls {[HR (bpm) 70.06 ± 6.63]; [R-R (ms) 865.11 ± 78.39]}. It was observed a lower HRV for middle-aged CON {[RMSSD (ms) 20.23 ± 5.87], [SDNN (ms) 37.79 ± 10.15] and [SD1 (ms) 14.31 ± 4.15]} compared to YC {[RMSSD (ms) 43.33 ± 26.41], [SDNN (ms) 67.07 ± 28.77] and [SD1 (ms) 30.66 ± 18.69; p < .05]}. These last age-related differences were not observed for MS and EN. Conclusion For master athletes, regardless of whether they are trained in endurance or sprinters, both training modes revealed to be equally beneficial in attenuating the effects of aging on the autonomic balance.
... It is not novelty that chronic and regular exercise training has positive effects on autonomic nervous system increasing HRV [26][27][28][29][30][31][32][33]. Elite and master endurance athletes seem to have better autonomic function which is represented by elevated parasympathetic heart modulation than their untrained counterparts [27,34]. ...
... Some previous findings in elite young athletes suggested a better autonomic balance of endurance athletes in comparison to sprinters [38]. In spite of the beneficial effects of lifelong endurance training had been widely demonstrated [27][28][29][30][31][32][33], there are few reports regarding the health profile of middle-aged athletes who have a life history of high-intensity training in speed and power, such as master sprinters [36]. ...
... Fractal analysis, through Detrended fluctuation analysis (DFA) technique, could be considered as a modification of spectral analysis; but unlike the latter, the former is thought not to be polluted by changes in the external environment [15][16][17], what makes it especially suitable for assessing HR dynamics in field-based situations. However, only a pair of studies regarding post exercise HRV recovery had previously focused on gender comparison [18,19]. Brown and Brown [18] found no significant differences in any frequency domain HRV index after a VO 2 max test to exhaustion in a trained Master athlete's sample. ...
... However, only a pair of studies regarding post exercise HRV recovery had previously focused on gender comparison [18,19]. Brown and Brown [18] found no significant differences in any frequency domain HRV index after a VO 2 max test to exhaustion in a trained Master athlete's sample. On the contrary, Mendonca et al. [19], in a non-athletes sample, showed that cardiac autonomic function of women is greater affected by supra maximal exercise than that of men. ...
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Regarding the importance of recovery in sport performance, assessment of post-exercise Heart Rate (HR) Dynamics has become a useful tool to understand such an individual process. Heart Rate Variability (HRV) analysis is widely used as a non-invasive marker of Autonomic Nervous System regulation of HR, where the nonlinear methods (Detrended Fluctuation Analysis (DFA)) have become a promising complementary analysis technique. In order to deepen on the effects of supra maximal complex efforts, integrating specific endurance and strength requirements on cardiac autonomic regulation, our research group is working in different protocols looking for the analysis of specific responses under supra maximal exertion. Therefore, our purpose was to analyze the immediate 10 min recovery timeline following a supra maximal specific Judo test in twenty-four judokas from the Spanish National Team (16 males and 8 females, 24.40 ± 0.97 years), deepening on gender differences. Consistent with previous research on supra maximal protocols, both HRV indices and Short-Term Scaling Exponent (α1), stemmed from DFA, appeared severely depressed after the test. Moreover, a negative correlation was found between final isometric pull-up drill and both lnTP (r=-0.457; p<0.05) and lnLF (r=-0.496; p<0.05), thus suggesting a crucial role for isometric strength requirements in cardiac autonomic recovery after exercise. At the same time, while performance showed a large gender difference (p<0.05; d=0.90), no significant gender differences were found either in HRV indices or in α1. However, when analyzing distance scores to optimal value of α1=1 (|1- α1|), men displayed significantly greater results, thus implying an improved recovery ability. Eventually, our results corroborate that nonlinear methods, compared to linear HRV indices, are capable of detecting subtler changes in HR behaviour.
... Та ко ђе, у овој гру пи на ла зи се ве ли ки број мла дих ис пи та ни ка ко ји ни су на ви кли на ла бо ра то риј ске усло ве те сти ра ња, те је за то њи хо ва ср ча на фре квен ци ја у сто је ћем по ло жа ју то ком ми ро ва ња би ла ве ћа од уоби ча је не ју тар ње. Вред но сти ср ча не фре квен ци је то ком пе ри о да опо рав ка ис пи та ни ка на ше сту ди је (ср ча на фре квен ци ја се у пр вом му ну ту опо рав ка сма њи ла за 23% код фи зич ки ак тив них, а за 12% код фи зич ки не ак тив них ис пи та ни ка у од но су на мак си мал ну ср ча ну фре квен ци ју) у скла ду су с на ла зи ма дру гих сту ди ја, ко је та ко ђе по ка зу ју да се вред но сти овог па ра ме тра сма њу ју бр же на кон ин тен зив не фи зич ке ак тив но сти код спор ти ста у по ре ђе њу са не спор ти сти ма [23,24]. Сма тра се да из ра же на ак тив ност ва гу са и де при ми ра на сим па тич ка ак тив ност у ста њу опо рав ка од ли ку ју вр хун ске спор ти сте, као још је дан од на чи на адап та ци је кар ди о ва ску лар ног си сте ма на ин тен зив ну фи зич ку ак тив ност [23]. ...
... Вред но сти ср ча не фре квен ци је то ком пе ри о да опо рав ка ис пи та ни ка на ше сту ди је (ср ча на фре квен ци ја се у пр вом му ну ту опо рав ка сма њи ла за 23% код фи зич ки ак тив них, а за 12% код фи зич ки не ак тив них ис пи та ни ка у од но су на мак си мал ну ср ча ну фре квен ци ју) у скла ду су с на ла зи ма дру гих сту ди ја, ко је та ко ђе по ка зу ју да се вред но сти овог па ра ме тра сма њу ју бр же на кон ин тен зив не фи зич ке ак тив но сти код спор ти ста у по ре ђе њу са не спор ти сти ма [23,24]. Сма тра се да из ра же на ак тив ност ва гу са и де при ми ра на сим па тич ка ак тив ност у ста њу опо рав ка од ли ку ју вр хун ске спор ти сте, као још је дан од на чи на адап та ци је кар ди о ва ску лар ног си сте ма на ин тен зив ну фи зич ку ак тив ност [23]. Ва тер по ло је фи зи о ло шки врло зах те ван спорт, јер се са сто ји од сме њи ва ња ве о ма ин тен зив не ак тив но сти, ко ја тра је кра ће од 15 се кун ди, на кон ко је сле де пе ри о ди ак тив но сти сла би јег ин тен зи те та, ко ји тра ју кра ће од 20 се кун ди, што овај спорт ка те го ри ше као ме шо вит [1]. ...
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Introduction: Specific morphological and functional characteristics of athletes have a significant role in determining athletes' sports results and can be also used to assess the athlete's individual potential. Objective: The aim of the study was to compare anthropometric characteristics and cardiovascular parameters in trained subjects to those of untrained subjects. Methods: A total number of 25 trained (17.30 +/- 0.83 years) and 21 (18.52 +/- 1.52 years) untrained male subjects participated in this study. Body weight and height were measured and these values were used to compute body mass index (BMI).The bioelectrical impedance analysis (BIA) method was used to estimate body fat percentage (%BF). Cardiovascular parameters were monitored in rest (rest heart rate, systolic and diastolic blood pressure) during ergospirometric testing (maximal oxygen consumption, maximal heart rate) and in recovery (heart rate in the first and third minute of recovery). Results: Body mass, height and BMI (p<0.01) were significantly higher, although BF% was lower in trained group when compared to untrained, but the difference was not statistically significant. Heart rate in rest and recovery were significantly lower (p<0.05) in trained group when compared to untrained, although maximal oxygen consumption and maximal heart rate were significantly higher in trained group (p<0.01, p<0.05, respectevely). Conclusion: Our results show that in trained subjects, water polo players, regular intense physical activity lead to adaptive changes of anthropometric parameters and adaptive changes on the cardiovascular system.
... Heart rate variability (HRV) refers to the beat-to-beat alterations in heart rate, largely due to fluctuating influences of the autonomic nervous system (ANS). The analysis of the HRV through linear and non-linear analytical techniques permits a non-invasive window on the ANS control (Aubert, Seps & Beckers, 2003;Brown & Brown, 2007). HRV seems to be a marker of both dynamic and cumulative load. ...
... HRV seems to be a marker of both dynamic and cumulative load. HRV, as a dynamic marker of load, appears to be responsive and sensitive to acute mental and physical stress (Task Force, 1996;Brown, 2007). On the other hand, HRV as a marker of cumulative load reflects the wear and tear on the individual over longer periods and declines in ageing due to the decrease in efferent parasympathetic (vagal) tone and the reduced β-adrenergic responsiveness (Task Force, 1996;Gorman & Slone, 2000). ...
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Heart rate variability (HRV) refers to the beat-to-beat variation in heart rate, largely due to fluctuating influences of the autonomic nervous system. There are indications that active participation in sport can alter the resting HRV and autonomic nervous system balance. The aim of this preliminary study was to determine whether different sports have different effects on autonomic balance, and whether HRV differs when top performers from their respective fields are compared. HRV measured in a control group and three groups of elite South African athletes were compared: endurance athletes, field hockey players and skydivers. Time domain, frequency domain and Poincaré analyses of baseline HRV were used to determine whether a difference exists between the three groups. Results were compared by means of a Kruskal-Wallis one way analysis of variance statistical test. This study indicated statistically significant differences between elite athletes from different sport types and a control group with regard to HRV and resting autonomic regulation of cardiac function. Of the three groups the endurance athletes had the highest HRV, as well as the highest vagal tone. The skydivers recorded the lowest HRV with sympathetic nervous system dominance. The control group and hockey players showed intermediate values between the other two groups for all parameters. Different types of sports influence resting autonomic balance to different extents. The results of this study point towards higher fitness levels, in terms of autonomic control of cardiac function in participants involved in aerobic-demanding sports activities. Lower HRV and increased sympathetic CV influence in the skydiving group may indicate increased dysrhythmogenic risk. Further studies conducted during non-participating periods and also in the later, post-participation years are recommended.
... Та ко ђе, у овој гру пи на ла зи се ве ли ки број мла дих ис пи та ни ка ко ји ни су на ви кли на ла бо ра то риј ске усло ве те сти ра ња, те је за то њи хо ва ср ча на фре квен ци ја у сто је ћем по ло жа ју то ком ми ро ва ња би ла ве ћа од уоби ча је не ју тар ње. Вред но сти ср ча не фре квен ци је то ком пе ри о да опо рав ка ис пи та ни ка на ше сту ди је (ср ча на фре квен ци ја се у пр вом му ну ту опо рав ка сма њи ла за 23% код фи зич ки ак тив них, а за 12% код фи зич ки не ак тив них ис пи та ни ка у од но су на мак си мал ну ср ча ну фре квен ци ју) у скла ду су с на ла зи ма дру гих сту ди ја, ко је та ко ђе по ка зу ју да се вред но сти овог па ра ме тра сма њу ју бр же на кон ин тен зив не фи зич ке ак тив но сти код спор ти ста у по ре ђе њу са не спор ти сти ма [23,24]. Сма тра се да из ра же на ак тив ност ва гу са и де при ми ра на сим па тич ка ак тив ност у ста њу опо рав ка од ли ку ју вр хун ске спор ти сте, као још је дан од на чи на адап та ци је кар ди о ва ску лар ног си сте ма на ин тен зив ну фи зич ку ак тив ност [23]. ...
... Вред но сти ср ча не фре квен ци је то ком пе ри о да опо рав ка ис пи та ни ка на ше сту ди је (ср ча на фре квен ци ја се у пр вом му ну ту опо рав ка сма њи ла за 23% код фи зич ки ак тив них, а за 12% код фи зич ки не ак тив них ис пи та ни ка у од но су на мак си мал ну ср ча ну фре квен ци ју) у скла ду су с на ла зи ма дру гих сту ди ја, ко је та ко ђе по ка зу ју да се вред но сти овог па ра ме тра сма њу ју бр же на кон ин тен зив не фи зич ке ак тив но сти код спор ти ста у по ре ђе њу са не спор ти сти ма [23,24]. Сма тра се да из ра же на ак тив ност ва гу са и де при ми ра на сим па тич ка ак тив ност у ста њу опо рав ка од ли ку ју вр хун ске спор ти сте, као још је дан од на чи на адап та ци је кар ди о ва ску лар ног си сте ма на ин тен зив ну фи зич ку ак тив ност [23]. Ва тер по ло је фи зи о ло шки врло зах те ван спорт, јер се са сто ји од сме њи ва ња ве о ма ин тен зив не ак тив но сти, ко ја тра је кра ће од 15 се кун ди, на кон ко је сле де пе ри о ди ак тив но сти сла би јег ин тен зи те та, ко ји тра ју кра ће од 20 се кун ди, што овај спорт ка те го ри ше као ме шо вит [1]. ...
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Introduction Specific morphological and functional charac-teristics of athletes have a significant role in determining ath-letes’ sports results and can be also used to assess the athlete’s individual potential. Objective The aim of the study was to compare anthropometric characteristics and cardiovascular par ameters in trained subjects to those of untrained subjects. Methods A total number of 25 trained (17.30±0.83 years) and 21 (18.52±1.52 years) untrained male subjects participated in this study. Body weight and height were measured and th ese values were used to compute body mass index (BM I). The bioelec trical impedance analysis (BIA) method was use d to estimate body fat percentage (%BF). Cardiovascular parameters were monitored in rest (rest heart rate, systolic and diastolic blood pressure) during ergospirometric tes ting (maximal oxygen consumpti on, maximal heart rate) and in recovery (heart rate in the first and third minute of recovery). Results Body mass, height and BMI (p<0.01) were significantly higher, although BF% was lower in trained group when com- pared to untrained, but the difference was not statistically significant. Heart rate in rest and recovery were significantly lower (p<0.05) in trained group when compared to untrained, although maximal oxygen consumption and maximal heart rate were significantly higher in trained group (p<0.01, p<0.05, respectevely). Conclusion Our results show that in trained subjects, water polo players, regular intense physical activity lead to adaptive changes of anthropometric parameters and adaptive changes on the cardiovascular system. Keywords: anthropometry; heart rate; VO2max; athletes
... Among these new approaches, fractal analysis, through Detrended fluctuation analysis (DFA) technique, could be considered as a modification of spectral analysis; but less affected by changes in the external environment (Huikuri et al., 2003;Makikallio et al., 2001;Tulppo et al., 2005), what makes it especially suitable for assessing HR dynamics in field-based situations. Similarly, only a pair of studies regarding post-exercise HRV recovery had previously focused on gender comparison (Brown and Brown, 2007;Mendonca et al., 2010). Brown and Brown (2007) found no significant differences in any frequency domain HRV index after a VO2max test to exhaustion in a trained Master athletes sample. ...
... Similarly, only a pair of studies regarding post-exercise HRV recovery had previously focused on gender comparison (Brown and Brown, 2007;Mendonca et al., 2010). Brown and Brown (2007) found no significant differences in any frequency domain HRV index after a VO2max test to exhaustion in a trained Master athletes sample. On the contrary, very recently Mendonca et al. (2010), in a non-athletes sample, showed that cardiac autonomic function of women is greater affected by supramaximal exercise than that of men. ...
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Heart Rate Dynamics analysis has become a useful tool to understand the cardiac autonomic regulation inside the sport performance recovery processes. Emerging nonlinear methods have been employed to analyze recovery following different supramaximal exercises, although there is little information about upper-limb explosive-strength endurance efforts. Therefore, our purpose was to analyze the immediate 10 min recovery timeline following a specific Judo test in twenty-four judokas from the Spanish National Team (16 males and 8 females, 24.40 ± 0.97 years) paying special attention to heart rate fractal dynamics (i.e. α1 and |1- α1|) and gender differences. Performance results confirmed the maximum exertion in the test, with significant better performance for men (BSJT T-Score: 311.96 ± 34.72, 276.09 ± 44.14; p<0.05; RPE: 19.44 ± 1.26, 19.25 ± 1.16; male vs female). Heart Rate Variability indices and Short-Term Scaling Exponent (α1) appeared severely altered. Men displayed lower values for α1 during the first five minutes of recovery (1.142 ± 0.262 vs. 1.323 ± 0.237; p<0.05). Similarly, men showed better distance scores to optimal value of α1=1 during both the first (0.251 ± 0.152 vs. 0.349 ± 0.190; p<0.05) and the second 5-minutes recovery epochs (0.355 ± 0.199 vs. 0.513 ± 0.251; p<0.01), despite there being no differences during the exercise phase neither in the former nor in the latter. In addition, a negative correlation was found between time achieved at the final isometric pull-up exercise and both lnTP (r=-0.457; p<0.05) and lnLF (r=-0.496; p<0.05). Consistent with previous research in neuromuscular protocols, our results show a great autonomic dysregulation following a supramaximal upper-limb effort, suggesting a crucial role for isometric strength. Significant better performance with also significant better |1- α1| point to a larger recovery capacity in men, though further studies should be done to relate this better cardiac autonomic recovery with a previous better performance.
... Heart rate variability (HRV) refers to the beat-to-beat alterations in heart rate, largely due to fluctuating influences of the autonomic nervous system (ANS). The analysis of the HRV through linear and non-linear analytical techniques permits a non-invasive window on the ANS control (Aubert, Seps & Beckers, 2003;Brown & Brown, 2007). HRV seems to be a marker of both dynamic and cumulative load. ...
... HRV seems to be a marker of both dynamic and cumulative load. HRV, as a dynamic marker of load, appears to be responsive and sensitive to acute mental and physical stress (Task Force, 1996;Brown, 2007). On the other hand, HRV as a marker of cumulative load reflects the wear and tear on the individual over longer periods and declines in ageing due to the decrease in efferent parasympathetic (vagal) tone and the reduced β-adrenergic responsiveness (Task Force, 1996;Gorman & Slone, 2000). ...
... Studies of heart rate following heavy exercise in subjects before and after a period of endurance training show that recovery becomes significantly faster after training (Goldberger et al. 2006;Seiler et al. 2007;Martinmäki & Rusko, 2008). Furthermore, comparisons between highly trained endurance athletes and untrained control subjects show that heart rate falls more quickly after a bout of high-intensity exercise in the athletes (Brown & Brown, 2007;Borresen & Lambert, 2008). The immediate rapid reduction in heart rate is largely eliminated by cholinergic blockade with intravenous atropine (Savin et al. 1982;Imai et al. 1994;Fisher et al. 2006;Borresen & Lambert, 2008). ...
... The pattern of parasympathetic reactivation after exercise has been confirmed by studies using a variety of indices of heart rate variability, both in the time domain and in the frequency domain (Savin et al. 1982;Hautala et al. 2001;Goldberger et al. 2006;Brown & Brown, 2007;Kaikkonen et al. 2007;Murrell et al. 2007;Martinmäki & Rusko, 2008;Sztajzel et al. 2008). In summary, the rapid heart rate decrease that occurs promptly when exercise ceases is entirely due to increase in cardiac vagal activity, and the subsequent slow exponential decay in heart rate results from algebraic summation of an increasing vagal inhibitory effect and a gradually subsiding excitatory sympatho-adrenal action. ...
Article
The Olympic biathlon is a very demanding physical event that requires high oxygen delivery, good cross-country skiing skills and skilful use of a rifle. Like all high-performance endurance athletes, high cardiac vagal tone is a characteristic and extends the range over which cardiac output can increase. In the biathlete, however, the enhanced vagal control of the heart also allows a strategy for better control of stability needed for accurately firing a rifle at the end of each lap of the race. The role of endurance training, central command, reflexes from muscle, and of the carotid-cardiac baroreceptor reflex in changing vagal tone during intense exercise and recovery is discussed.
... Modifications of the autonomic control depend on type, duration, and intensity of exercise (Stanley et al., 2013;Michael et al., 2017). Usually, following an exercise of high intensity and long duration the magnitude of RR fluctuations decreased, thus suggesting a more limited vagal regulation compared to pre-exercise situation (Arai et al., 1989;Brown and Brown, 2007;Murrell et al., 2007). However, a less pronounced increase of the indexes of sympathetic modulation in response to active standing has been noted 90 min after a marathon (Murrell et al., 2007). ...
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Cardiac autonomic control is commonly assessed via the analysis of fluctuations of the temporal distance between two consecutive R-waves (RR). Cardiac regulation assessment following high intensity physical exercise is difficult due to RR non-stationarities. The very short epoch following maximal sprint exercise when RR remains close to its lowest value, i.e., the PLATEAU, provides the opportunity to evaluate cardiac regulation from stationary RR sequences. The aim of the study is to evaluate cardiac autonomic control during PLATEAU phase following 60-m maximal sprint and compare the results to those derived from sequences featuring the same length as the PLATEAU and derived from pre-exercise and post-exercise periods. These sequences were referred to as PRE and POST sequences. RR series were recorded in 21 subjects (age: 24.9 ± 5.1 years, 15 men and six women). We applied a symbolic approach due to its ability to deal with very short RR sequences. The symbolic approach classified patterns formed by three RRs according to the sign and number of RR variations. Symbolic markers were compared to more classical time and frequency domain indexes. Comparison was extended to simulated signals to explicitly evaluate the suitability of methods to deal with short variability series. A surrogate test was applied to check the null hypothesis of random fluctuations. Over simulated data symbolic analysis was able to separate dynamics with different spectral profiles provided that the frame length was longer than 10 cardiac beats. Over real data the surrogate test indicated the presence of determinism in PRE, PLATEAU, and POST sequences. We found that the rate of patterns with two variations with unlike sign increased during PLATEAU and in POST sequences and the frequency of patterns with no variations remained unchanged during PLATEAU and decreased in POST compared to PRE sequences. Results indicated a sustained sympathetic control along with an early vagal reactivation during PLATEAU and a shift of the sympathovagal balance toward vagal predominance in POST compared to PRE sequences. Time and frequency domains markers were less powerful because they were dominated by the dramatic decrease of RR variance during PLATEAU.
... Finally, the SBP, DBP, and MABP were significantly higher in the overweight/ obese during the recovery period after isotonic exercise. A delay in the recovery of the normal, resting autonomic regulation of the heart rate following exercise may indicate subclinical pathology, and a prolonged tachycardia may predict mortality (Brown & Brown, 2007). The raised blood pressure as seen in this study could be due to a reduced BRS and is likely to lead to an increased blood pressure variability which can further aggravate the reduction in BRS (Rosengård-Bärlund et al., 2011). ...
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Autonomic imbalance in overweight/obese persons could lead to an increased risk of cardiovascular complications including hypertension and arrhythmias. Baroreceptor reflex sensitivity is a sensitive indicator to detect an altered sympathovagal balance in overweight/obese individuals. This study investigated the effects of overweight/obesity on baroreceptor sensitivity in young Saudi males at rest and in response to physiological challenges. Subjects and methods: In this cross-sectional study, spontaneous baroreceptor sensitivity at rest and in response to deep breathing, isometric hand grip exercise and moderate intensity isotonic exercise were recorded in 20 normal weight and 20 overweight/obese subjects. Finger arterial blood pressure signal, recorded through Finometer, was used to calculate baroreceptor sensitivity through cross-correlation method. The baroreceptor sensitivity data were log transformed before application of parametric tests. Results: The spontaneous baroreceptor sensitivity was similar in both groups at baseline, but exhibited a significant increase during deep breathing only in normal weight (p < .001). Immediately after the isotonic exercise the baroreceptor sensitivity was significantly lower than baseline in both normal weight and overweight/obese and remained significantly lower in overweight/obese individuals compared to normal weight (p < .05) throughout the recovery period. There was a significant rise in baroreceptor sensitivity after isometric exercise in overweight/obese group only (p = .001). Pearson's correlation showed a significant negative correlation of baroreceptor sensitivity with body mass index during deep breathing (r = -.472, p = .004) and in post-isotonic exercise recovery period (r = -.414, p = .013). Conclusion: A significantly reduced baroreceptor sensitivity response to deep breathing, reduced baroreceptor sensitivity recovery after isotonic exercise, and an exaggerated shoot up after isometric exercise in overweight/obese suggests an altered sympathovagal balance. Baroreceptor sensitivity measurements in response to physiological challenges, deep breathing, and isotonic exercise, may be more sensitive investigations for detection of early attenuation of cardiac autonomic function. This would enable timely intervention thereby delaying complications and improving the quality of life.
... After acute exercise, time-domain measures such as mean normal-to-normal RR intervals (RRNN) and the SD of normal-to-normal RR intervals (SDNN) are lower than pre-exercise values. These changes are accompanied with significantly modulated HRV frequencydomain measures, from very low-frequency spectral power (VLF) to high-frequency spectral power (HF), and have been observed in both untrained (37) and trained (7) individuals. Michael et al. (33) indicated that low-frequency spectral power (LF) is dependent on both sympathetic and parasympathetic ANS activity and that the ratio of low-frequency to high-frequency spectral power (LF/HF) is indicative of sympathovagal balance where one system dominates over the other. ...
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Hebisz, RG, Hebisz, P, and Zatoń, MW. Heart rate variability after sprint interval training in cyclists and implications for assessing physical fatigue. J Strength Cond Res XX(X): 000-000, 2020-This study evaluated the time- and frequency-domain indexes of heart rate variability (HRV) during sprint interval exercise test (SIXT) and identify the onset of fatigue by HRV concurrent with changes in average (Pavg) and peak (Ppeak) power output, total oxygen uptake (V[Combining Dot Above]O2tou), and blood hydrogen (H) and lactate (La) concentrations. Twenty-seven cyclists performed 4 sets of SIXT in which each set consisted of four 30-second maximal sprints interspersed with 90 seconds of low-intensity cycling. Each set was separated by 25-40 minutes of recovery. Before beginning each set, HRV was analyzed by time (mean normal-to-normal RR intervals [RRNN], SD of normal-to-normal RR intervals [SDNN], and square root of the mean squared difference between successive normal-to-normal RR intervals [RMSSD]) and frequency (total spectral power [T] and very low- [VLF], low- [LF], and high-frequency [HF] spectral power) domain methods. Pavg, Ppeak, and V[Combining Dot Above]O2tou were recorded in each set, and H and La were measured after each set. RRNN, SDNN, and VLF decreased in the second set, whereas all time and frequency indexes of HRV decreased in the third and fourth set. Pavg and H decreased, while V[Combining Dot Above]O2tou increased in the fourth set. Ppeak decreased in the second, third, and fourth set. Correlations were found between the changes in the time and frequency indexes of HRV with H, La, and V[Combining Dot Above]O2tou. The results indicate that HRV does not reflect the onset of physical fatigue in SIXT as was observed in Pavg and no correlation was found between the changes in HRV with Pavg and Ppeak.
... Whereas measuring VO 2 uptake or blood lactate level during exercise may be a complicated task in outdoor conditions, monitoring HR values is a relatively simple procedure when using a portable HR monitor system outdoors. Indeed, it is documented that HR and VO 2 are linearly related in trained and untrained individuals throughout the major portion of the exercise range (Borresen & Lambert, 2008;Brown & Brown, 2007). Therefore, monitoring HR responses is considered to be a practical and popular method for measuring exercise intensity level, especially in aerobic-type exercise. ...
... The trained group had a significantly faster absolute and relative HRr and a higher relative VO 2 max than the untrained group. This was demonstrated both in the maximal testing session, as well as the submaximal exercise session, and these findings are consistent previous research (Borresen, Lambert, 2008;Brinkworth et al., 2006;Brown, Brown, 2007;Bunn et al., 2017;Carroll et al., 2012;Dixon, Kamath, McCartney, Fallen, 1992;Lamberts, Swart, Capostagno, Noakes, Lambert, 2010;Sugawara, Murakami, Maeda, Kuno, Matsuda, 2001). Interestingly, the graphical representations of the absolute and relative HRr show that the gap in recovery between the two groups tends to be the same regardless of the time point (Figures 1 and 2). ...
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The purpose of this study was to evaluate differences in heart rate recovery (HRr) in trained and untrained adults, while assessing the role of physiological and emotional factors. Eighteen untrained and 21 trained participants completed a maximal exercise test and a 20-min treadmill exercise at 55–70% heart rate reserve, and emotional state was assessed prior to exercise. Multiple regression was used to assess relationships between heart rate recovery and physiological and emotional assessments. The trained group had a higher relative maximal oxygen consumption (p < 0.001), lower resting heart rate (p < 0.001), and faster short- and long-term heart rate recovery (p < 0.05) than the untrained group. Resting heart rate was the most predictive measure with HRr for the trained group (R = 0.551–0.818), whereas resting heart rate, maximal heart rate, and fitness were predictors of recovery in the untrained group (R = 0.764–0.977). The results show the predominant parasympathetic influence on HRr in the trained group, but indicates influence of fitness and exercise intensity on recovery in the untrained group. Thus, fitness appears to influence HRr in those only with low fitness. This notion may help influence the behavior of untrained individuals to improve fitness to reduce risk of mortality and morbidity.
... In healthy populations, heart rate and perceived exertion are used as accurate measures of exercise intensity (Noble and Robertson, 1996). At the cessation of intense exercise the heart rate decreases, in most cases at a significantly faster 141 rate in physically fit individuals than those from the sedentary population (Brown and Brown, 2007). Heart rate recovery (HRR) to pre-exercise measures is considered to be almost entirely regulated by vagal reactivation mediated by parasympathetic activity of the autonomic nervous system (ANS). ...
... Published articles on the effect of exercise on the ANS as measured by HRV and BPV are summarised in three categories: the response of the ANS measured during a bout of exercise, 3,5,14,16,26,29,37,42,43,51 and directly after a bout of exercise (recovery measurements), 3,9,[22][23][24]28,40,49 and the long-term effect of regular exercise on the ANS. 4,8,[10][11][12][13]15,17,18,[19][20][21]25,27,[30][31][32][34][35][36]38,39,45,47 The results of 10 articles on ANS response measured during exercise are shown in Table I. ...
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Motivation. There is growing interest in the use of cardiovascular variability indicators as measures of autonomic activity, even though reported results are not always comparable or as expected. This review aims to determine the consistency of results reported on the autonomic response to physical exercise as measured by heart rate variability, blood pressure variability and baroreceptor sensitivity. Method. An Ovid MEDLINE Database search for the period 1950 - March 2008 produced 46 articles for review. The published articles that evaluate the effect of exercise on the autonomic nervous system (ANS) are summarised in three categories: the response of the ANS during a bout of exercise, directly after exercise (recovery measurements), and after a long-term exercise programme. Results. Articles on the effect of training on the ANS as measured by cardiovascular variability indicators show increased variability, decreased variability, and no change in variability. Conclusion. Findings in this review emphasise that standardisation and refinement of these measuring tools are essential to produce results that can be repeated and used as reference. Standardisation is essential as these measurements are increasingly employed in studies regarding investigations of central autonomic regulation, those exploring the link between psychological pro cesses and physiological functioning, and those indicating ANS activity in response to exercise, training and overtraining. This review shows that important aspects are inter-individual differences, duration and intensity of the exercise programme, and choice and specific implementation of variability analysis techniques. South African Journal of Sports Medicine Vol. 20 (4) 2008: pp. 102-108
... In all these studies HRV was recorded at rest. However, if HRV is assessed after exercise, these differences do not seem to be corroborated; in fact, Brown did not found differences when HRV was examined in 13 athletes (7 men and 6 women) after a high-intensity exercise 28 . ...
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Objectives: To analyze heart rate variability (HRV) at rest and after 3 consecutive badminton matches played in a short period of time (2 or 3 days) in order to assess the effect of accumulated tiredness and if there were differences between males and females under these conditions. Methods: We have studied 19 badminton players divided into two groups: 11 females (age 17,88+3,01 years) and 8 males (age 18,16±2,87 years). In four different championships we took initial records in a large number of players, but we selected for the study to those players who played at least 3 matches before of being eliminated from the tournament. The heartbeat signal was recorded beat to beat for 20 minutes in supine position before the competition and after 3 matches. The initial record (baseline) was made at their own room one day after arriving in the host city and the another three records were made after finishing the match, between 15 and 25 minutes (average 17.14 + 3,93 minutes). The usual parameters in the time domine as well as the transverse (SD1) and the longitudinal axis (SD2) of the Poincare' plot were calculated. Results: All parameters in time domine were significantly lower after the matches than basal but the differences between the matches were not significant. No significant differences were found between males and females in none of the parameters at the four situations. SD1, SD2 and the ratio SD1/SD2 in the Poincare' plot post-matches were lower than the baseline, but without significant gender differences. Conclusions: HRV decreases after matches but without differences due to the number of matches and these changes are the same for men and women.
... Published articles on the effect of exercise on the ANS as measured by HRV and BPV are summarised in three categories: the response of the ANS measured during a bout of exercise, 3,5,14,16,26,29,37,42,43,51 and directly after a bout of exercise (recovery measurements), 3,9,[22][23][24]28,40,49 and the long-term effect of regular exercise on the ANS. 4,8,[10][11][12][13]15,17,18,[19][20][21]25,27,[30][31][32][34][35][36]38,39,45,47 The results of 10 articles on ANS response measured during exercise are shown in Table I. ...
Article
Full-text available
Heart rate variability (HRV), blood pressure variability (BPV) and baroreceptor sensitivity (BRS) are often used as measures of auto-nomic activity, even though reported results are not always comparable or as expected. It is known that endurance athletes have lower average resting heart rates than non-exercising individuals. 33, 50 However, other exercise-induced autonomic influences on cardiac control are far more controversial. Autonomic control via sympathetic and parasympathetic modulation of the heart has been assessed by power spectral analysis of HRV 1,7,33,41,46,48,50 and BPV. 44,52 Different frequency peaks reflect specific physiological stimuli and it is possible to estimate the involvement of the autonomic nervous system (ANS) influence and balance in heart rate (HR) regulation. 1,2,6 With power spectral analysis of HR, two characteristic peaks between 0.04 Hz and 0.15 Hz (A) and between 0.15 Hz and 0.5 Hz (B) are used to quantify the autonomic balance in terms of the low-frequency (LF)/ high-frequency (HF) ratio. 1,6,48 Peak A is found in the region of Mayer waves (0.1 Hz) and is situated in the so-called LF area. It appears to be linked to the combined activities of the sympathetic and parasympathetic branches of the ANS. Peak B is synchronous with respiration, reflects vagal activity, is situated in the so-called HF area REVIEW Autonomic response to exercise as measured by cardio-vascular variability Abstract Motivation. There is growing interest in the use of cardiovas-cular variability indicators as measures of autonomic activity, even though reported results are not always comparable or as expected. This review aims to determine the consistency of results reported on the autonomic response to physical exercise as measured by heart rate variability, blood pressure variability and baroreceptor sensitivity.
... The effect of exercise on the ANS as measured by cardiovascular variability quantification (HRV and BPV) can be summarised in three categories: the response of the ANS measured during a bout of exercise, [25- 34] directly after a bout of exercise [31] [32] [35] [36] [37] [38] [39] [40] [41] [42] and the long-term effect of regular exercise on the ANS (Table 1.) [34] [42-77]. ...
Chapter
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Heart rate variability (HRV) analysis is a popular tool for the assessment of autonomic cardiac control. These measurements are increasingly employed in studies ranging from investigations of central autonomic regulation; to studies exploring the link between psychological processes and physiological functioning; to the indication of ANS activity in response to exercise, training and overtraining. Many publications elaborate on the effect of exercise on HRV and by implication on cardiac functioning. However, results on the effects of exercise on the autonomic control of the heart are often contradictory and incomplete in the normal population and in disease. In order to understand and employ the effects of exercise in patients with cardiovascular disorders it is of primary importance that agreement should be reached on the effects of exercise in the normal and healthy population. In this chapter, a selection of older and more recent publications, investigating autonomic training effects as measured by cardiovascular variability indicators, are summarized. Reasons for heterogeneous results are identified and discussed. The chapter concludes with specific recommendations for future research.
... Para obtenção dos índices espectrais, o tacograma de Os registros para análises dos índices de VFC por meio de métodos lineares podem ser obtidos em curtos períodos (2, 5, 15 minutos) ou em longos períodos (24 horas), o que é mais comum na prática clínica [25], sendo que um mínimo de 256 intervalos RR é recomendado para esta análise [7,9]. Em seus experimentos, para análise de índices lineares de VFC, Seiler et al. [18], Brown & Brown [46] e Parekh & Lee [47] descartaram períodos iniciais de captação, nos quais ocorrem muitas oscilações e o sistema não se encontra em estado de estabilidade. Para análise dos índices no domínio do caos, um número maior de intervalos RR é recomendado. ...
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... These authors did not investigate the underlying mechanism that contributed to the positive effects following chronic L-arginine supplementation ; however, speculation regarding increased coronary and peripheral blood flow because of inhibition of endothelin has been proposed [28]. Heart rate increases linearly as exercise intensity increases29303132 and well documented response of HR can be used as an indicator of exercise intensity [33,34].Figure 3 Heart rate (beats per minute; bpm) in untrained and trained subjects at PRE (i.e. rest), POST UPPER (i.e., following bench press protocol), and POST LOWER (i.e., following leg press protocol). ...
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Dietary supplements containing L-arginine are marketed to improve exercise performance, but the efficacy of such supplements is not clear. Therefore, this study examined the efficacy of acute ingestion of L-arginine alpha-ketoglutarate (AAKG) muscular strength and endurance in resistance trained and untrained men. Eight resistance trained and eight untrained healthy males ingested either 3000mg of AAKG or a placebo 45 minutes prior to a resistance exercise protocol in a randomized, double-blind crossover design. One-repetition maximum (1RM) on the standard barbell bench press and leg press were obtained. Upon determination of 1RM, subjects completed repetitions to failure at 60% 1RM on both the standard barbell bench press and leg press. Heart rate was measured pre and post exercise. One week later, subjects ingested the other supplement and performed the identical resistance exercise protocol. Our data showed statistical significant differences (p<0.05) between resistance trained and untrained males for both 1RM and total load volume (TLV; multiply 60% of 1RM times the number of repetitions to failure) for the upper body. However, 1RM and TLV were not statistically different (p>0.05) between supplementation conditions for either resistance trained or untrained men in the bench press or leg press exercises. Heart rate was similar at the end of the upper and lower body bouts of resistance exercise with AAKG vs. placebo. The results from our study indicate that acute AAKG supplementation provides no ergogenic benefit on 1RM or TLV as measured by the standard barbell bench press and leg press, regardless of the subjects training status.
... Thus, the higher LF/HF ratio and the significant reduction of HF power after submaximal exercise seem to reflect a sympathovagal imbalance, with sympathetic dominance and reduced vagal modulation. Both are associated to higher susceptibility to malignant ventricular arrhythmias and sudden death (Schuchert et al., 2005; Brown & Brown, 2007). The mechanism underlying the cardiac autonomic dysfunction in AAS-abusing subjects remains unknown. ...
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This study aimed to evaluate if androgenic-anabolic steroids (AAS) abuse may induce cardiac autonomic dysfunction in recreational trained subjects. Twenty-two men were volunteered for the study. The AAS group (n = 11) utilized AAS at mean dosage of 410 ± 78.6 mg/week. All of them were submitted to submaximal exercise testing using an Astrand-Rhyming protocol. Electrocardiogram (ECG) and respired gas analysis were monitored at rest, during, and post-effort. Mean values of VO(2) , VCO(2) , and V(E) were higher in AAS group only at rest. The heart rate variability variables were calculated from ECG using MATLAB-based algorithms. At rest, AAS group showed lower values of the standard deviation of R-R intervals, the proportion of adjacent R-R intervals differing by more than 50 ms (pNN50), the root mean square of successive differences (RMSSD), and the total, the low-frequency (LF) and the high-frequency (HF) spectral power, as compared to Control group. After submaximal exercise testing, pNN50, RMSSD, and HF were lower, and the LF/HF ratio was higher in AAS group when compared to control group. Thus, the use of supraphysiological doses of AAS seems to induce dysfunction in tonic cardiac autonomic regulation in recreational trained subjects.
... We suggest that these vigorous-intensity exercises performed at È85% of HR peak perturb cardiac vagal activity longer in women than in men. Previous studies have mainly shown no gender differences in HR and HRV during the acute phase of postexercise recovery, whereas there are inconsistent results regarding postexercise hemodynamics (5,7,11,30). Gender differences in the long-term (up to 48 h) recovery of cardiac autonomic regulation after endurance-type exercise have not been reported previously. ...
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To test the utility of HR variability (HRV) in daily exercise prescription in moderately active (approximately two exercises per week) men and women. A total of 21 men and 32 women were divided into standard training (ST: males = 7 and females = 7), HRV-guided training (HRV-I: males = 7 and females = 7; HRV-II: females = 10), and control (males = 7 and females = 8) groups. The 8-wk aerobic training period included 40-min exercises at moderate and vigorous intensities (70% and 85% of maximal HR). The ST group was instructed to perform two or more sessions at moderate and three or more sessions at vigorous intensity weekly. HRV-I and HRV-II groups trained on the basis of changes in HRV, measured every morning. In the HRV-I group, an increase or no change in HRV resulted in vigorous-intensity training on that day. Moderate-intensity exercise or rest was prescribed if HRV had decreased. The HRV-II group performed a vigorous-intensity exercise only when HRV had increased. Peak oxygen consumption (VO2peak) and maximal workload (Loadmax) were measured by a maximal bicycle ergometer test before and after the intervention. The changes in VO2peak did not differ between the training groups either in men or in women. In men, the change in Loadmax was higher in the HRV-I group than in the ST group (30 +/- 8 vs 18 +/- 10 W, P = 0.033). In women, no differences were found in the changes in Loadmax between the training groups (18 +/- 10, 15 +/- 11, and 18 +/- 5 W for ST, HRV-I, and HRV-II, respectively). The HRV-II group performed fewer vigorous-intensity exercises than the ST and HRV-I groups (1.8 +/- 0.3 vs 2.8 +/- 0.6 and 3.3 +/- 0.2 times per week, respectively, P < 0.01 for both). HRV measurements are beneficial in exercise training prescription in moderately active men and women. Women benefit from HRV guidance by achieving significant improvement in fitness with a lower training load.
... Regardless of age, endurance athletes demonstrate a higher parasympathetic modulation and have a particularly high global heart rate variability compared with sedentary individuals, indicating that endurance activity may have a favourable effect on the cardiac autonomic profile (Sztajzel et al. 2008). Veteran athletes demonstrate a decreased heart rate (HR) variability in both time and frequency domains suggesting an increased parasympathetic withdrawal during the autonomic control of post-exercise tachycardia (Brown and Brown 2007). Pollock et al. (1997) conducted a 20-year review of veteran athletes documenting a linear decrease in maximal HR of 5–7 beat min -1 decade -1 that was independent of continued high-intensity training. ...
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The cardiovascular benefits of exercise are well known. In contrast, the impact of lifelong endurance exercise is less well understood. Long-term high-intensity endurance exercise is associated with changes in cardiac morphology together with electrocardiographic alterations that are believed to be physiologic in nature. Recent data however has suggested a number of deleterious adaptive changes in cardiac structure, function and electrical activity, together with peripheral and cerebral vascular structure and function. This review serves to detail knowledge in relation to; (1) Cardiac structure and function in veteran endurance athletes focusing on the differentiation of physiological and pathological changes in cardiac remodelling; (2) Cardiac electrical activity and the veteran endurance athlete with attention to arrhythmias, the substrate for arrhythmia generation and the clinical significance of such arrhythmias; (3) Peripheral and cerebral vascular structure and function in ageing and endurance-trained individuals; and (4) directions for future research.
... The records for analysis of HRV indexes by linear methods can be obtained in short periods (2, 5, 15 minutes) or long periods (24 hours), which is more common in clinical practice [25], whereas a minimum of 256 RR intervals is recommended for this analysis [7,9]. Seiler et al. [18], Brown & Brown [46] and Parekh & Lee [47] in their experiments for analysis of linear indexes, dismissed the initial periods of capture, on which many oscillations occur and the system is not in a stability state. For analysis of the indexes in the chaos domain, a larger number of RR intervals is recommended. ...
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Autonomic nervous system (ANS) plays an important role in the regulation of the physiological processes of the human organism during normal and pathological conditions. Among the techniques used in its evaluation, the heart rate variability (HRV) has arising as a simple and non-invasive measure of the autonomic impulses, representing one of the most promising quantitative markers of the autonomic balance. The HRV describes the oscillations in the interval between consecutive heart beats (RR interval), as well as the oscillations between consecutive instantaneous heart rates. It is a measure that can be used to assess the ANS modulation under physiological conditions, such as wakefulness and sleep conditions, different body positions, physical training and also pathological conditions. Changes in the HRV patterns provide a sensible and advanced indicator of health involvements. Higher HRV is a signal of good adaptation and characterizes a health person with efficient autonomic mechanisms, while lower HRV is frequently an indicator of abnormal and insufficient adaptation of the autonomic nervous system, provoking poor patient's physiological function. Because of its importance as a marker that reflects the ANS activity on the sinus node and as a clinical instrument to assess and identify health involvements, this study reviews conceptual aspects of the HRV, measurement devices, filtering methods, indexes used in the HRV analyses, limitations in the use and clinical applications of the HRV.
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Objectives: The aim of the present study was to examine the effects of habitual exercise training and metabolic health on basal cardiac autonomic function and cardiac autonomic recovery after exercise in healthy postmenopausal women (PMW). Methods: Habitually aerobically trained PMW (PMW-tr; 56 ± 1y; n = 11), and untrained PMW (PMW-un; 57 ± 1y; n = 13) and premenopausal women (PreM; ages 26 ± 1y; n = 14) were studied. Cardiac autonomic function, assessed using heart rate variability (HRV), was measured before and one hour after 45-minutes of moderate-intensity exercise (60% VO2peak). Fast Fourier frequency domain measures of high (HF; 0.15 Hz-0.4 Hz), low (LF; 0.04 Hz-0.15 Hz), very low (VLF; 0.01 Hz-0.04 Hz), and Total (VLF+LF+HF) HRV were assessed. Serum estradiol, insulin, and glucose were determined, and HOMA-IR, an index of insulin resistance, was calculated. Results: In PMW groups, body composition and serum markers did not differ (P>0.05). Pre-exercise, heart rate was lower (P<0.05) in PMW-tr than PMW-un, yet HRV did not differ (P>0.05). In PMW-tr only, HF was inversely associated (P<0.05) with insulin (r = -0.738) and HOMA-IR (r = -0.758). In PreM, HRV was higher than PMW (P<0.05) and was positively correlated with estradiol (P<0.05). Postexercise, HRV was decreased within all groups (P<0.05) yet remained higher in PreM (P<0.05), and similar (P>0.05) between PMW. Conclusion: Basal and postexercise HRV does not differ between habitually aerobically trained and untrained PMW. However, greater insulin sensitivity was associated with higher cardiac parasympathetic tone in trained PMW only. Exercise training may favorably modulate cardiac autonomic-metabolic interactions in PMW.
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The purpose of this study was to determine potential adverse cardiac effects of chronic endurance training by comparing sympathovagal modulation via heart rate variability (HRV) and heart rate recovery (HRR) in middle-aged endurance athletes (EA) and physically active individuals (PA) following maximal exercise. Thirty-six (age, 53 ± 5 years) EA and 19 (age, 56 ± 5 years) PA were recruited to complete a 2-week exercise diary and graded exercise to exhaustion. Time domain and power spectral HRV analyses were completed on recorded R-R intervals. EA had a greater HRR slope following exercise (95% confidence interval, 0.0134–0.0138 vs. 0.0101–0.0104 beats/s; p < 0.001). While EA had greater HRR at 1–5 min after exercise (all p < 0.01), PA and EA did not differ when expressed as a percentage of baseline heart rate (130 ± 19 vs. 139 ± 19; p = 0.2). Root mean square of successive differences in R-R intervals (rest and immediately after exercise) were elevated in EA (p < 0.05). Low-frequency (LF) and high-frequency (HF) spectral components were nonsignificantly elevated after exercise (p = 0.045–0.147) in EA while LF/HF was not different (p = 0.529–0.986). This data suggests greater HRR in EA may arise in part due to a lower resting HR. While nonsignificant elevations in HF and LF in EA produces a LF/HF similar to PA, absolute spectral component modulation differed. These observations require further exploration. Novelty Acute effects of exercise on HRV in EA compared with a relevant control group, PA, are unknown. EA had greater HRR and nonsignificant elevations in LF and HF compared with PA, yet LF/HF was not different. Future work should explore the implications of this observation.
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The authors compared the linear and nonlinear heart rate variability dynamics from rest through maximal exercise in postmenopausal women who trained at either moderate or high intensities. The outcome variables included the RR triangular index, TINN, SD1, SD2, SD1/SD2, DFA α1, DFA α2, and α1/α2. Maximal exercise reduced SD1, SD2, DFA α1, DFA α2, α1/α2, RRTri, and TINN in both groups and increased SD1/SD2 ( p < .05). Two minutes of active recovery produced significant increases in SD1, SD2, DFA α1, and TINN, compared with exercise in both groups ( p < .0001). There was also a significant main effect between groups for RRTri during exercise recovery, with the moderate group achieving higher levels ( p < .04). The authors have shown that both moderate and vigorous exercise training can lead to a healthy response to maximal exercise and recovery, with the moderate group having a slightly improved recovery in the triangular index.
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Increased parasympathetic tone achieved with endurance training may provide cardioprotection after menopause. To compare heart rate variability (HRV) from rest through maximal exercise and recovery in trained postmenopausal women. Thirty-six postmenopausal women who self-reported training at either moderate (MOD; 3-5.9 METS; 58.9+/-4.4 year) or vigorous (VIG; >6 METS; 59.7+/-5.2 year) intensities participated. HRV was measured for 5 min in the supine position, in the last minute of the VO(2)max test and after 2 min of active recovery. HRV in MOD and VIG was compared using a factorial ANOVA with repeated measures on time. MOD and VIG responded similarly over the three time periods for root mean square of sequential deviations (rMSSD), and high (HF) and low frequency (LF) power (p>0.05). Maximal exercise lowered rMSSD (3.3+/-0.08 vs. 1.2+/-0.06) and lnLF (4.1+/-0.05 vs. 3.3+/-0.13) and increased lnHF (3.3+/-0.14 vs. 4.0+/-0.10; p<0.01) from resting. However, active recovery restored lnHF (3.3+/-0.11) and lnLF (4.1+/-0.08) from maximal values (p<0.01). Our findings suggest that moderate and vigorous exercise training may enhance HRV recovery following one bout of maximal exercise in older women.
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Treatment of congestive heart failure (CHF) remains one of the challenging problems in cardiology. In recent years, the method of multifrequency bio-impendancemetry is used in patients with CHF for the assessment of water imbalance and determination of its severity. The aim of the study was to determine the diagnostic capabilities of bio-impendancemetry in evaluation of the early manifestations of CHF. The study included 92 healthy individuals, and 335 patients who were hospitalized in the cardiology department with NYHA I-II functional class (FC) of chronic CHF. The echocardiography, rheography and biochemical examination were performed for determination of FC of CHF. Procedures were repeated at day 5 of hospitalization, 6-minute walk test was performed to assess physical tolerance and objectification of the functional status of patients with CHF. 45 patients had signs of CHF FC III-IV, therefore, they were excluded from the study. Analysis of endpoints was conducted by telephone survey in 1 year after discharge from the hospital. The results of the comparison of the predictive value of different methods for diagnosing CHF showed maximum sensitivity for brain natriuretic peptide (BNP) which was 82%, specificity was 88%. The 6-minute walk test showed the lowest values of sensitivity and specificity (sensitivity 67%, specificity 72%) as well as leg impedance at low frequencies (LF) (sensitivity 69%, specificity 74%). The values for the leg impedance at high frequencies (HF) were as follows: sensitivity 68%, specificity 97%. High predictive value of a positive result (PPV) was shown in phase angle (91%) and BNP (91%). Left ventricle ejection fraction(LVEF) measurements had the lowest PPV (72%).
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Background: Firefighters' cardiovascular fitness remains a foremost concern among fire departments and organizations, yet very little research has been conducted to examine the cardiovascular fitness adaptations that occur during firefighter training academies. Objective: To describe the cardiovascular adaptations observed among firefighter recruits during firefighter training academies using measures of estimated maximal oxygen uptake (VO2max) and heart rate recovery (ΔHR). Methods: Firefighter recruits (n = 41) enrolled in a 16-week firefighter training academy completed a 5-minute step test during the first, eighth, and sixteenth week of training. Repeated measures analysis of variance (RM ANOVA) calculations were conducted to determine changes in estimated VO2max and ΔHR. Results: Results of the RM ANOVA calculations revealed that mean estimated VO2max and mean ΔHR differed significantly between time points: F(2, 80) = 75.525, p < 0.001, and F(2, 80) = 4.368, p = 0.016, respectively. No significant changes were observed in mean estimated VO2max and mean ΔHR beyond the eighth week of training. No significant relationship was identified between estimated VO2max and ΔHR. Conclusions: Although firefighter recruits' estimated VO2max and ΔHR change significantly over the course of the firefighter training academy, the measures may not be equal predictors of cardiovascular fitness.
Supplements marketed as nitric oxide stimulators have recently become extremely popular among people engaged in resistance exercise training, but their efficacy has not been fully documented. Thus, the aim of the current study was to investigate the ergogenic properties of acute L-arginine α-ketoglutarate ingestion in untrained and resistance exercise trained young females. Six untrained and 13 resistance-exercise trained young, healthy females ingested either 3,000 mg of L-arginine α-ketoglutarate or a placebo 45 minutes prior to a resistance exercise protocol in a randomized, double-blind crossover design. One repetition maximum on the chest press was obtained. Furthermore, total load volume (calculated as 60% of one repetition maximum X number of repetitions to failure) was determined. One week later, subjects ingested the other supplement, and the same exercise protocol was performed. Our data showed significant differences (p < 0.05) between untrained and resistance-exercise trained subjects for both one repetition maximum and total load volume. However, one repetition maximum, and total load volume were no statistically significant different (p > 0.05) between subjects supplemented with L-arginine α-ketoglutarate or placebo for either untrained or resistance-exercise trained females. In addition, acute L-arginine α-ketoglutarate ingestion did not result in significant differences (p < 0.05) in heart rate or blood pressure before or after exercise. In conclusion, the results from our study indicate that acute ingestion of a nitric oxide stimulator provides no ergogenic benefit on maximal strength or muscular endurance in females as measured by the chest press exercise, regardless of the subject's training status.
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Endurance training decreases resting and submaximal heart rate, while maximum heart rate may decrease slightly or remain unchanged after training. The effect of endurance training on various indices of heart rate variability remains inconclusive. This may be due to the use of inconsistent analysis methodologies and different training programmes that make it difficult to compare the results of various studies and thus reach a consensus on the specific training effects on heart rate variability. Heart rate recovery after exercise involves a coordinated interaction of parasympathetic re-activation and sympathetic withdrawal. It has been shown that a delayed heart rate recovery is a strong predictor of mortality. Conversely, endurance-trained athletes have an accelerated heart rate recovery after exercise. Since the autonomic nervous system is interlinked with many other physiological systems, the responsiveness of the autonomic nervous system in maintaining homeostasis may provide useful information about the functional adaptations of the body. This review investigates the potential of using heart rate recovery as a measure of training-induced disturbances in autonomic control, which may provide useful information for training prescription.
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During postexercise recovery, heart rate (HR) initially falls rapidly, followed by a period of slower decrease, until resting values are reached. The aim of the present work was to examine the differences in the recovery heart rate (RHR) between athletes engaged in static and dynamic sports. The study subjects were 294 federated sportsmen competing at the national and international level in sports classified using the criteria of Mitchell et al. as either prevalently static (N.=89) or prevalently dynamic (N.=205). Within the dynamic group, the subjects who practised the most dynamic sports were assigned to further subgroups: triathlon (N.=20), long distance running (N.=58), cycling (N.=28) and swimming (N.=12). All athletes were subjected to a maximum exertion stress test and their HR recorded at 1, 2, 3 and 4 min (RHR1,2,3,4) into the HR recovery period. The following indices of recovery (IR) were then calculated: IR1 = (HRpeak - RHR1,2,3,4) / (HRmax - HRrest) * 100, IR2 = (HRpeak - RHR1,2,3,4)/(HRmax / HRpeak), and IR3 = HRpeak - RHR1,2,3,4. The differences in the RHR and IR for the static and dynamic groups were examined using two way ANOVA. The RHR at minutes 2 (138.7±15.2 vs. 134.8±14.4 beats·min-1) and 3 (128.5±15.2 vs. 123.3±14.4 beats·min-1) were significantly higher for the static group (Group S) than the dynamic group (Group D), respectively. Significant differences were seen between Group D and S with respect to IR1 at minutes 1 (26.4±8.7 vs. 24.8±8.4%), 2 (43.8±8.1 vs. 41.5±7.8%), 3 (52.1±8.3 vs. 49.1±8%) and 4 (56.8±8.6 vs. 55.4±7.4%) of recovery. For IR2, significant differences were seen between the same groups at minutes 2 (59.7±12.5 vs. 55.9±10.8 beats·min-1) and 3 (71.0±13.5 vs. 66.1±11.4 beats·min-1) of recovery. Finally, for IR3, the only significant difference between Group D and S was recorded at minute 3 of recovery (72.2±12.5 vs. 66.2±11.5 beats·min-1). This work provides information on RHR of a large population of elite Spanish athletes, and shows marked differences in the way that HR recovers in dynamic and static sports.
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Despite a growing clinical interest in determining the heart rate recovery (HRR) response to exercise, the limits of a normal HRR have not yet been well established. This study was designed to examine HRR following a controlled maximal exercise test in healthy, physically active adult men. The subjects recruited (n = 789) performed a maximal stress test on a treadmill. HRR indices were calculated by subtracting the first and third minute heart rates (HRs) during recovery from the maximal HR obtained during stress testing and designated these as HRR-1 and HRR-3, respectively. The relative change in HRR was determined as the decrease in HR produced at the time points 1 and 3 min after exercise as a percentage of the peak HR (%HRR-1/HRpeak and %HRR-3/HRpeak, respectively). Percentile values of HRR-1 and HRR-3 were generated for the study population. Mean HHR-1 and HHR-3 were 15.24 ± 8.36 and 64.58 ± 12.17 bpm, respectively, and %HRR-1/HRpeak and %HRR-3/HRpeak were 8.60 ± 4.70 and 36.35 ± 6.79 %, respectively. Significant correlation was detected between Peak VO2 and HRR-3 (r = 0.36; p < 0.001) or %HRR-3/HRpeak (r = 0.23; p < 0.001). Our study provides normality data for HRR following a maximal Ergometry test obtained in a large population of physically active men.
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ABSTRACT Glycine-arginine-α-ketoisocaproic acid (GAKIC) has been proposed to increase anaerobic high-intensity exercise performance in male subjects. However, the effects of GAKIC ingestion in female subjects have not been studied. Therefore, the purpose of this study was to investigate the effects of GAKIC supplementation on total load volume (i.e., mass lifted) and metabolic parameters during repeated bouts of submaximal leg extensions in college-age females. Nine resistance-trained females participated in a randomized, counterbalanced, double blind study. Subjects were randomly assigned to placebo or GAKIC (10.2 g) and performed six sets of 50% of one repetition maximum leg extensions (two legs simultaneously) to failure. One week later, subjects ingested the other supplement and performed the same exercise protocol. Furthermore, blood lactic acid, blood glucose, and heart rate were also measured preexercise and 5 s after the completion of the exercise protocol (postexercise). GAKIC supplementation significantly increased leg extension total load volume (GAKIC = 1721.7 ± 479.9 kg; placebo = 1479.1 ± 396.8 kg, p < .01). Heart rate and blood lactic acid were significantly increased (p < .01 for both measures) postexercise compared to preexercise, but were not significantly different between GAKIC and placebo (p = .40 for heart rate; p = .88 for lactic acid). Blood glucose was significantly decreased (p = .03) postexercise compared to preexercise, but was not significantly different (p = .78) between GAKIC and placebo. Collectively, these findings suggest that GAKIC increased lower body resistance performance in trained college-age females; however, these findings are not necessarily generalizable.
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Dietary supplements containing L-arginine have been marketed with the purpose of increasing vasodilatation, and thus, blood and oxygen supply to the exercising muscle. The present study evaluated the acute effect of L-arginine supplementation on indicators of NO production, nitrite (NO2 -) + nitrate (NO3 -) (NOx), in healthy subjects. Plasma concentrations of asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) have also been addressed. Seventeen healthy males participated in a randomized, double-blind, placebo-controlled study. Blood samples were drawn from a left antecubital vein at baseline (T0). Afterwards, subjects were randomly submittedto 6 g of oral L-arginine supplementation (as L-arginine hydrochloride) or placebo (as corn starch); afterwards, the subjects remained at rest in supine position and blood samples were drawn again at 30 (T1), 60 (T2), 90 (T3) and 120 minutes (T4) after supplementation. To analyze NO production, NO3 - was converted to NO2 - by nitrate reductase, followed by the derivatization of NO2 - with 2,3-diaminonaphthalene. NOx, ADMA and SDMA were analyzed using a high-performance liquid chromatography system and monitored with a fluorescence detector. Two-way ANOVA with repeated measures showed no significant changes in NOx concentrations on the L-arginine group as compared to placebo group at any of the fivetime points (T0: 17.6 ± 3.9 vs 14.6 ± 2.3 μmol/L; T1: 15.8 ± 2.4 vs 14.3 ± 1.7 μmol/L; T2: 16.8 ± 4.9 vs 13.7 ± 2.7 μmol/L; T3: 16.7 ± 3.9 vs 14.6 ± 2.1 μmol/L; T4: 15.1 ± 2.8 vs 13.5 ± 3.5 μmol/L). Furthermore, plasma levels of ADMA and SDMA were not statistically significant between the L-arginine and placebo groups at T0 (0.43 ± 0.19 vs 0.39 ± 0.15 μmol/L and 1.83 ± 1.13 vs 1.70 ± 0.62 μmol/L), respectively. In conclusion, acute L-arginine supplementation does not increase plasma concentration of NOx in healthy individuals with normal plasma concentrations of ADMA.
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Differences in the duration of the cycles reflects the balance of the sympathetic and parasympathetic influence on the heart. Variance in the heart rate correlates to the breathing cycle, to baroreflex sensitivity, to day and night alternations and to changes in the vegetative tone evoked by physical exercises. Analysis of the time and/or frequency power domain of the heart rate variance is expected to have diagnostic value in physiological and pathological situations as adaptation to training, overtraining, heart disease etc. Both time- and frequency domains reflect the same physiological phenomenon but from different point of view. Vagus tonus is reflected in the high frequency part of the range of variance, while an increased sympathetic tone enriches the low frequency part of the variations of the duration of the consecutive heart cycles. This technically simple and relatively inexpensive method has inspired a couple of clinical and sports medical studies. Certain tendencies seem to be clear, but for individual diagnosis or for prognosis the data must be treated very carefully.
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The aims of this investigation were to identify possible associations between the resting high frequency component of heart rate variability and measures of ventilatory efficiency, determined during exercise, in a group of endurance trained athletes. V'E, V'CO2, and V'O2 were measured during incremental exercise up to the anaerobic threshold (AT) and up to volitional exhaustion (V'O2 max) in 12 subjects. Resting high frequency heart rate variability (HF(NU)), determined using spectral analysis of ECG traces, was correlated with the V'E vs. V'CO2 slope calculated from data up to the AT, where a negative linear relation between the V'E vs. V'CO2 slope and HF (NU) was recorded (R(2)=0.69). Also, resting HF (NU) was correlated with the V'E vs. V'CO (2) slope, when the data used for slope calculation included all V'E vs. V'CO2 data up to V'O2 max (R(2)=0.56). However, there was no evidence of association between the minimum V'E:V'CO (2) and resting HF(NU) (R(2)=0.08). Negative relations between V'E vs. V'CO2 slope and resting HF(NU) suggest that HF(NU) plays a role in matching blood flow in the lung to alveolar ventilation throughout the ventilatory cycle.
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Power spectrum analysis of heart rate fluctuations provides a quantitative noninvasive means of assessing the functioning of the short-term cardiovascular control systems. We show that sympathetic and parasympathetic nervous activity make frequency-specific contributions to the heart rate power spectrum, and that renin-angiotensin system activity strongly modulates the amplitude of the spectral peak located at 0.04 hertz. Our data therefore provide evidence that the renin-angiotensin system plays a significant role in short-term cardiovascular control in the time scale of seconds to minutes.
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The effect of exercise training on heart rate variability (HRV) and improvements in peak oxygen consumption ($$\dot V{\text{O}}_{\text{2}}$$ peak) was examined in sedentary middle-aged men. The HRV and absolute and relative$$\dot V{\text{O}}_{\text{2}}$$ peak of training (n = 19) and control (n = 15) subjects were assessed before and after a 24-session moderate intensity exercise training programme. Results indicated that with exercise training there was a significantly increased absolute and relative$$\dot V{\text{O}}_{\text{2}}$$ peak (P < 0.005) for the training group (12% and 11% respectively) with no increase for the control group. The training group also displayed a significant reduction in resting heart rate; however, HRV remained unchanged. The trained subjects were further categorized into high (n = 5) and low (n = 5) HRV groups and changes in$$\dot V{\text{O}}_{\text{2}}$$ peak were compared. Improvements in both absolute and relative$$\dot V{\text{O}}_{\text{2}}$$ peak were significantly greater (P > 0.005) in the high HRV group (17% and 20% respectively) compared to the low HRV group (6% and 1% respectively). The groups did not differ in mean age, pretraining oxygen consumption, or resting heart rate. These results would seem to suggest that a short aerobic training programme does not alter HRV in middle-aged men. Individual differences in HRV, however, may be associated with$$\dot V{\text{O}}_{\text{2}}$$ peak response to aerobic training.
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Heart rate variability (HRV) appears to be a strong predictor of death. The reproducibility of HRV measurements in patients with stable coronary artery disease (CAD) who have daily life myocardial ischemia, however, is unknown. Thirty patients with stable CAD (25 men and 5 women; aged 62 +/- 8 years) with daily life ischemia were studied with 2 consecutive 24-hour Holter monitoring recordings. Intra- and interobserver reproducibility of the HRV measures was high, with correlations ranging from 0.990 to 0.999 (p < 0.0001). Strong correlations between time and frequency domain HRV measures were observed (range 0.912 to 0.963; p < 0.0001). Both the frequency and duration of ischemia, measured by ST change, varied significantly by day for each patient (s = 155.5; p < 0.0001; s = 232.5, p < 0.0001, respectively). Correlations for HRV measurements between days remained high (range 0.871 to 0.983; p < 0.0001), despite stratification by magnitude of daily ischemia. Thus, 24-hour HRV measurements are stable in CAD patients with daily life myocardial ischemia over a short period, despite varying magnitudes of daily ischemia. These results support the use of HRV as a clinical tool and an outcome measure in future CAD intervention studies using commercially available equipment.
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The increase in heart rate that accompanies exercise is due in part to a reduction in vagal tone. Recovery of the heart rate immediately after exercise is a function of vagal reactivation. Because a generalized decrease in vagal activity is known to be a risk factor for death, we hypothesized that a delayed fall in the heart rate after exercise might be an important prognostic marker. For six years we followed 2428 consecutive adults (mean [+/-SD] age, 57+/-12 years; 63 percent men) without a history of heart failure or coronary revascularization and without pacemakers. The patients were undergoing symptom-limited exercise testing and single-photon-emission computed tomography with thallium scintigraphy for diagnostic purposes. The value for the recovery of heart rate was defined as the decrease in the heart rate from peak exercise to one minute after the cessation of exercise. An abnormal value for the recovery of heart rate was defined as a reduction of 12 beats per minute or less from the heart rate at peak exercise. There were 213 deaths from all causes. A total of 639 patients (26 percent) had abnormal values for heart-rate recovery. In univariate analyses, a low value for the recovery of heart rate was strongly predictive of death (relative risk, 4.0; 95 percent confidence interval, 3.0 to 5.2; P<0.001). After adjustments were made for age, sex, the use or nonuse of medications, the presence or absence of myocardial perfusion defects on thallium scintigraphy, standard cardiac risk factors, the resting heart rate, the change in heart rate during exercise, and workload achieved, a low value for heart-rate recovery remained predictive of death (adjusted relative risk, 2.0; 95 percent confidence interval, 1.5 to 2.7; P<0.001). A delayed decrease in the heart rate during the first minute after graded exercise, which may be a reflection of decreased vagal activity, is a powerful predictor of overall mortality, independent of workload, the presence or absence of myocardial perfusion defects, and changes in heart rate during exercise.
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The objectives of this review are to discuss the diversity of mechanisms that may explain the association between heart rate (HR) variability and mortality, to appraise the clinical applicability of traditional and new measures of HR variability and to propose future directions in this field of research. There is a large body of data demonstrating that abnormal HR variability measured over a 24-h period provides information on the risk of subsequent death in subjects with and without structural heart disease. However, the mechanisms responsible for this association are not completely established. Therefore, no specific therapy is currently available to improve the prognosis for patients with abnormal HR variability. Reduced HR variability has been most commonly associated with a risk of arrhythmic death, but recent data suggest that abnormal variability also predicts vascular causes of death, progression of coronary atherosclerosis and death due to heart failure. A consensus is also lacking on the best HR variability measure for clinical purposes. Time and frequency domain measures of HR variability have been most commonly used, but recent studies show that new analysis methods based on nonlinear dynamics may be more powerful in terms of risk stratification. Before the measurement of HR variability can be applied to clinical practice and used to direct therapy, more precise insight into the pathophysiological link between HR variability and mortality are needed. Further studies should also address the issue of which of the HR variability indexes, including the new nonlinear measures, is best for clinical purposes in various patient populations.
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Harmful cardiac events occurs frequently after exercise. However, the cardiac autonomic regulation after vigorous exercise is not well known. This study was designed to assess heart rate (HR) variability before and after a 75 km cross-country skiing race. HR variability was assessed by using standard statistical measures along with spectral and quantitative Poincarè plot analysis of HR variability in 10 healthy male subjects (age 36 +/- 11 years). The average HR was at the same level 1 day after the race as before the race, but on the second day, HR was significantly lower (P<0.001) compared with the prerace and 1 day after values. The normalized high-frequency (HF) spectral component of HR variability (nuHF) was lower (P<0.01) on the first day after the maximal exercise compared with the pre-exercise values but returned to or even exceeded the prerace level on the second day (P<0.01). The changes in short-term R-R interval variability analysed from the Poincaré plot were similar to those observed in the HF spectral component. The normalized low-frequency (LF) spectral component of HR variability (nuLF) was higher (P<0.01) on the first day after the exercise compared with the prerace levels and it also returned to the pre-exercise level or even dropped below it on the second day after the race. The mean time it took the HF spectral component to return to the pre-exercise level was 4.2 +/- 4.2 h (ranging from 0 to 12 h). This recovery time correlated inversely with the maximal oxygen consumption (VO2max) measured during the bicycle exercise test before the skiing race (r=-0.712, P<0.016). The cardiac vagal outflow is blunted for several hours after prolonged vigorous exercise. The recovery time of reduced vagal outflow depends on individual cardiorespiratory fitness and there is an accentuated rebound of altered autonomic regulation on the second day after prolonged exercise.
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The recovery of the baseline autonomic control of cardiovascular activity after exercise has not been extensively studied. In 12 healthy subjects, we assessed the time-course of recovery by autoregressive spectrum and cross-spectrum analysis of heart period and systolic blood pressure during the 3 h after the end of 20 min of steady-state exercise at 50% (light workload, LW) and 80% (moderate workload, MW) of the individual's anaerobic threshold. The electrocardiogram and non-invasive blood pressure were simultaneously recorded during 10 min periods in the sitting position, at rest before exercise, and at 15, 60 and 180 min of recovery after exercise. At 15 min we observed a persistent tachycardia and relative hypotension; after MW, at 60 min heart rate was still slightly higher. Spectrum and cross-spectrum analysis showed, at 15 min, an increase in the low frequency component of systolic blood pressure, a reduction in the high frequency component of heart rate (larger in MW), and a decrease in baroreceptor sensitivity. After 60 and 180 min none of these parameters was significantly different from those at rest, although, in MW, some subjects still displayed signs of sympathetic activation after 1 h. We concluded that, after 15 min of recovery, the cardiovascular reflexes were blunted, that sympathetic nerve activity was still enhanced, and that the tone in the vagus had not fully recovered. Only the persistent vagal restraint seemed to be exercise intensity-dependent. For complete restoration of autonomic control after LW 1 h of rest was sufficient, and just enough after MW.
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Endurance training induces reductions in both resting and postexercise heart rate (HR). If adaptation in cardiac autonomic regulation is a contributing factor in these reductions, changes in cardiac autonomic nervous system (ANS) should correspond to those in HR during an endurance-training program. We investigated the changes in resting and postexercise HR variabilities (both in the time and frequency domain) over a 6-wk training program. HR variability was measured five times in an endurance-training group (N = 7) and four times in a control group (N = 5) during the course of study. Endurance training decreased HR and increased indices of parasympathetic modulation measured both at rest and during postexercise recovery periods. Noteworthy is that no changes in either HR or indices of ANS modulation measured during postexercise recovery periods were detectable after the first 7 d of the study despite continued changes in resting HR and indices in ANS modulation measured between the 7th and 42nd days of the endurance-training program. The study demonstrates that with endurance-training changes in cardiac ANS modulation partly contribute to a decrease in HR at rest and during postexercise recovery period, and that adaptation of the cardiac autonomic control occurs sooner in immediate postexercise periods than at rest.
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To study the influences of a 1-year controlled, randomized endurance exercise training period on heart rate (HR) and blood pressure variability in a representative sample of Finnish men in their late middle age. Subjects were 140 sedentary men aged 53-63 years. The men were randomized into two identical groups: an intervention (EX) and a reference (CO) group. One hundred and twelve of them remained in the final analysis (EX: n=59, CO: n=53). EX trained for 30-60 min three to five times a week with the intensity of 40-60% of maximal oxygen consumption. In EX, 1 year of regular exercise training increased oxygen consumption at respiratory compensation threshold by 11% (P < or = 0.001) in a maximal cardiorespiratory test. Total power and very low frequency power of R-R interval variability (ms2) tended to increase in the EX group by 26 and 42% and to decrease in the CO group by 13 and 10% (interaction P<0.05 and P<0.01), respectively. There were no significant changes in blood pressure variability. Regular low- to moderate-intensity exercise training could retard the declining tendency in cardiac autonomic nervous function in older men during 1 year.
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Physical exercise is associated with parasympathetic withdrawal and increased sympathetic activity resulting in heart rate increase. The rate of post-exercise cardiodeceleration is used as an index of cardiac vagal reactivation. Analysis of heart rate variability (HRV) and complexity can provide useful information about autonomic control of the cardiovascular system. The aim of the present study was to ascertain the association between heart rate decrease after exercise and HRV parameters. Heart rate was monitored in 17 healthy male subjects (mean age: 20 years) during the pre-exercise phase (25 min supine, 5 min standing), during exercise (8 min of the step test with an ascending frequency corresponding to 70% of individual maximal power output) and during the recovery phase (30 min supine). HRV analysis in the time and frequency domains and evaluation of a newly developed complexity measure - sample entropy - were performed on selected segments of heart rate time series. During recovery, heart rate decreased gradually but did not attain pre-exercise values within 30 min after exercise. On the other hand, HRV gradually increased, but did not regain rest values during the study period. Heart rate complexity was slightly reduced after exercise and attained rest values after 30-min recovery. The rate of cardiodeceleration did not correlate with pre-exercise HRV parameters, but positively correlated with HRV measures and sample entropy obtained from the early phases of recovery. In conclusion, the cardiodeceleration rate is independent of HRV measures during the rest period but it is related to early post-exercise recovery HRV measures, confirming a parasympathetic contribution to this phase.
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This review examines the influence on heart rate variability (HRV) indices in athletes from training status, different types of exercise training, sex and ageing, presented from both cross-sectional and longitudinal studies. The predictability of HRV in over-training, athletic condition and athletic performance is also included. Finally, some recommendations concerning the application of HRV methods in athletes are made. The cardiovascular system is mostly controlled by autonomic regulation through the activity of sympathetic and parasympathetic pathways of the autonomic nervous system. Analysis of HRV permits insight in this control mechanism. It can easily be determined from ECG recordings, resulting in time series (RR-intervals) that are usually analysed in time and frequency domains. As a first approach, it can be assumed that power in different frequency bands corresponds to activity of sympathetic (0.04–0.15Hz) and parasympathetic (0.15–0.4Hz) nerves. However, other mechanisms (and feedback loops) are also at work, especially in the low frequency band. During dynamic exercise, it is generally assumed that heart rate increases due to both a parasympathetic withdrawal and an augmented sympathetic activity. However, because some authors disagree with the former statement and the fact that during exercise there is also a technical problem related to the non-stationary signals, a critical look at interpretation of results is needed. It is strongly suggested that, when presenting reports on HRV studies related to exercise physiology in general or concerned with athletes, a detailed description should be provided on analysis methods, as well as concerning population, and training schedule, intensity and duration. Most studies concern relatively small numbers of study participants, diminishing the power of statistics. Therefore, multicentre studies would be preferable. In order to further develop this fascinating research field, we advocate prospective, randomised, controlled, long-term studies using validated measurement methods. Finally, there is a strong need for basic research on the nature of the control and regulating mechanism exerted by the autonomic nervous system on cardiovascular function in athletes, preferably with a multidisciplinary approach between cardiologists, exercise physiologists, pulmonary physiologists, coaches and biomedical engineers.
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Potent cardioinhibitory vagal reflex resulting in bradycardia and hypotension has been observed under particular conditions of transmural inferior ischemia and its reperfusion, such as those observed with acute infarction. However, whether exercise-induced ischemia with ST depressions that is subendocardial and that might be recurrently experienced in daily activities can evoke this reflex remains unknown. In patients with exercise-induced ST depressions due to either inferior [right coronary artery stenosis (RCA), n = 52] or anterior ischemia [left anterior descending artery stenosis (LAD), n = 51], we evaluated post exercise vagal activity (from 0 to 6 min) by the time constant of heart rate (HR) decay and HR variability by 30-s averages of the absolute values of successive RR interval differences (DeltaRR). Exercise parameters were similar between groups. The time constant was slightly but significantly shorter in RCA than LAD patients (79 +/- 24 vs. 93 +/- 29 s, P < 0.01). More significantly, DeltaRR early after exercise (0.5-2.5 min) was approximately twofold greater in RCA than LAD patients (from +76 to +118%, P < 0.001), indicating pronounced vagal activity stimulated by inferior ischemia. Revascularization prolonged the time constant (P < 0.05) and attenuated recovery DeltaRR in RCA patients (P < 0.05, n = 10) but did not change both parameters in LAD patients (n = 12). As well as acute inferior infarction, exercise-induced inferior subendocardial ischemia, which might recurrently occur in daily activities, activates the cardioinhibitory reflex. These new findings must be taken into account in interpreting vagal activity in patients with coronary artery disease.
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The aim of the present study was to investigate the effect of a single bout of mild exercise on autonomic nervous system activity in healthy subjects. The study group comprised 18 healthy males, aged between 20 and 24 years, who had not been training regularly for the last 3 months. A supine recording of systolic arterial pressure (SAP) and RR interval and the administration of the phenylephrine test were performed at baseline and repeated after a 60-min recovery period following treadmill exercise training for 30 min at 65% of maximal heart rate. Mean SAP and RR interval, heart rate variability (HRV) indices (the standard deviation of normal-to-normal RR intervals (SDNN), the square root of the mean of squared differences between successive intervals and the percentage of adjacent RR intervals differing more than 50 ms), noninvasive spectral baroreflex sensitivity (Spe-BRS) and phenylephrine baroreflex sensitivity (Phe-BRS) were assessed before and after training. Mean SAP measured after exercise was lower than baseline (120+/-12 mmHg vs 128+/-12 mmHg, p = 0.05). Spe-BRS and Phe-BRS increased significantly after exercise, from 11.8+/-6.1 ms/mmHg to 16.0+/-7.8 ms/mmHg (p = 0.034), and from 16.0+/-8.8 ms/mmHg to 21.9+/-9.3 ms/mmHg (p = 0.022), respectively. A parallel increase was also observed in SDNN (from 81+/-44 ms to 96+/-53 ms, p = 0.02), but the other HRV indices showed no significant differences between pre- and post-exercise. A single session of mild exercise performed by sedentary young men leads to significant autonomic nervous system improvement, which suggests that even mild physical activity is beneficial for neural cardiac regulation and should be recommended to sedentary healthy subjects.
Article
Exercise training and heart rate variability in older people. Med. Sci. Sports Exerc., Vol. 31, No. 6, pp. 816-821, 1999. Purpose: Heart rate variability (HRV), a characteristic that is potentially increased by physical activity, has been associated with incidence of cardiac events and total mortality. Since the incidence of cardiac events among older people is high and their physical activity levels and HRV are generally low, it is important to investigate whether regular physical activity can modify HRV in this age group. The purpose of the study was to investigate the effect of regular physical activity on HRV in older men and women. Methods: In a randomized controlled trial, the effect of six months' training on HRV was investigated in a group of 51 older men and women (67.0 ± 5.1 yr). The training group gathered three times per week for 45 min supervised training. Results: At the end of the intervention period, HRV was higher primarily during the day. During daytime, the SD of all normal intervals (+6%) as well as the low frequency component (+15%) and the very low frequency component (+10%) of HRV were significantly increased (P < 0.05) as compared with the control group. Effects of training were most pronounced in subjects inactive in sports at baseline. Conclusion: This study demonstrates that regular physical activity increases HRV (specifically in the very low and low frequency components) in older subjects. Hence, in older subjects, physical training may be an effective means to modify positively a factor that is associated with increased incidence of cardiac events.
Article
Cardiovascular responses were examined in seven healthy male subjects during 10 min of recovery in the upright or supine position following 5 min of upright cycle exercise at 80% peak oxygen uptake. An initial rapid decrease in heart rate (f c) during the early phase of recovery followed by much slower decrease was observed for both the upright and supine positions. The average f c at the 10th min of recovery was significantly lower (P < 0.05) in the supine position than in the upright position, while they were both significantly greater than the corresponding pre-exercise levels (each P < 0.05). Accordingly, the amplitude of the high frequency (HF) component of R-R interval variability (by spectrum analysis) in both positions was reduced with a decrease in mean R-R interval, the relationship being expressed by a regression line – mean R-R interval = 0.006 × HF amplitude + 0.570 (r = 0.905, n = 28, P < 0.001). These results would suggest that the slower reduction in f c following the initial rapid reduction in both positions is partly attributable to a retardation in the restoration of the activity of the cardiac parasympathetic nervous system. Post-exercise upright stroke volume (SV, by impedance cardiography) decreased gradually to just below the pre-exercise level, whereas post-exercise supine SV increased markedly to a level similar to that at rest before exercise. The resultant cardiac output (Q˙ c) and the total peripheral vascular resistance (TPR) in the upright and supine positions returned gradually to their respective pre-exercise levels in the corresponding positions. At the 10th min of recovery, both average SV and Q˙ c were significantly greater (each P < 0.005) in the supine than in the upright position, while average TPR was significantly lower (P < 0.05) in the supine than in the upright position. In contrast, immediately after exercise, mean blood pressure dropped markedly in both the supine and upright positions, and their levels at the 10th min of recovery were similar. Therefore we concluded that arterial blood pressure is maintained relatively constant through various compensatory mechanisms associated with f c, SV, Q˙ c, and TPR during rest and recovery in different body positions.
Article
Physical training offers a potential non-pharmacological strategy for control of mild and borderline hypertension, but its effect on blood pressure is controversial. We investigated the effects of endurance training on waking and sleeping blood pressure and on baroreflex sensitivity in 16 borderline hypertensive patients. First, 8 patients were assessed before and after a 6-month endurance training programme. Then, when it was clear that blood pressures were lower after training, a further 8 patients were studied not only at the end of the training programme but also after 4 months' abstention from exercise (detraining). Measurements were taken of baroreflex sensitivity (response to iv phenylephrine), blood pressure, R-R interval, and blood pressure and R-R variability. Ambulatory blood pressures were measured in 13 patients (7 trained, 6 detrained) and sleep blood pressures in 6 patients (3 trained, 3 detrained). Increased fitness was associated with a decline in resting arterial blood pressure of 9·7 (SE 2·0) mm Hg systolic and 6·8 (1·2) mm Hg diastolic, and with a decline in ambulatory blood pressure of 4·8 (1·4) mm Hg and 7·5 (2·1) mm Hg, respectively; both p<0·05. Baroreflex sensitivity was 14·0 (1·8) ms/mm Hg in the unfit and 17·5 (2·0) ms/mm Hg in the fit; p < 0·05. Sleep blood pressures were not lower in the fit despite longer sleep R-R intervals. These findings indicate that, in some subjects with borderline or mild hypertension, a physical training programme is sufficient to bring the blood pressure within normal limits.
Article
Experiments were performed on anaesthetized dogs to determine the effects of moderate changes in PCO2 in the cephalic circulation on the inotropic state of the heart and on the reflex inotropic responses from changes in carotid sinus pressure. The cephalic circulation was perfused, through the brachiocephalic and left subclavian arteries, with blood taken from the superior vena cava and equilibrated with various gas mixtures in a gas exchange unit. The carotid sinus regions were vascularly isolated and perfused with arterial blood at controlled pressures. Cardiac inotropic responses were assessed from the maximum rate of change of left ventricular pressure (dP/dtmax) with heart rate and mean aortic pressure held constant. An increase in cephalic blood PCO2 resulted in an increase in dP/dtmax and an increase in the unpaced heart rate. Small, graded changes in cephalic PCO2 resulted in graded responses of dP/dtmax. A change in carotid sinus pressure resulted in a significantly greater response of dP/dtmax when cephalic PCO2 was high. After interruption of the left cardiac sympathetic nerves, the responses of dP/dtmax to changes in cephalic PCO2 and carotid sinus pressure were nearly abolished. These results indicate that the tension of carbon dioxide in the cephalic circulation is likely to be of importance in the control of the inotropic state of the heart. They also imply that, in studies of cardiovascular reflex responses, it is important to control the carbon dioxide tension in the arterial blood.
Article
The prognostic implications of alterations in heart rate variability have not been studied in a large community-based population. The first 2 hours of ambulatory ECG recordings obtained on original subjects of the Framingham Heart Study attending the 18th biennial examination were reprocessed to assess heart rate variability. Subjects with transient or persistent nonsinus rhythm, premature beats > 10% of total beats, < 1 hour of recording time, processed time < 50% of recorded time, and those taking antiarrhythmic medications were excluded. The associations between heart rate variability measures and all-cause mortality during 4 years of follow-up were assessed. There were 736 eligible subjects with a mean age (+/- SD) of 72 +/- 6 years. The following five frequency domain measures and three time domain measures were obtained: very-low-frequency power (0.01 to 0.04 Hz), low-frequency power (0.04 to 0.15 Hz), high-frequency power (0.15 to 0.40 Hz), total power (0.01 to 0.40 Hz), the ratio of low-frequency to high-frequency power, the standard deviation of total normal RR intervals, the percentage of differences between adjacent normal RR intervals that are > 50 milliseconds, and the square root of the mean of the squared differences between adjacent normal RR intervals. During follow-up, 74 subjects died. In separate proportional hazards regression analyses that adjusted for relevant risk factors, very-low-frequency power (P < .0001), low-frequency power (P < .0001), high-frequency power (P = .0014), total power (P < .0001), and the standard deviation of total normal RR intervals (P = .0019) were significantly associated with all-cause mortality. When all eight heart rate variability measures were assessed in a stepwise analysis that included other risk factors, low-frequency power entered the model first (P < .0001); thereafter, none of the other measures of heart rate variability significantly contributed to the prediction of all-cause mortality. A 1 SD decrement in low-frequency power (natural log transformed) was associated with 1.70 times greater hazard for all-cause mortality (95% confidence interval of 1.37 to 2.09). The estimation of heart rate variability by ambulatory monitoring offers prognostic information beyond that provided by the evaluation of traditional risk factors.
Article
This study addresses the long term and short term effects of heavy dynamic exercise on neural control of heart rate. A group of healthy controls was compared with (1) a group of trained athletes during a period of yearly rest (detrained) and (2) a group of trained athletes at the peak of their training routine. Additionally, a group of 10 controls was studied 1, 24, and 48 h after a single bout of maximal dynamic exercise. Spectral analysis of RR interval variability provided markers of sympathetic (low frequency, LF, 0.10 Hz) and vagal (high frequency, HF, 0.25 Hz) modulation of the sinoatrial node. (1) In detrained athletes resting bradycardia was accompanied by a predominant HF rhythmic component suggestive of a prevailing vagal tone. (2) Trained athletes showed a resting bradycardia together with high LF values, thus suggesting a more complex neural interaction modulating heart rate. An additional longitudinal part of the study, performed on a group of detrained athletes who were examined for the second time after resuming training, confirmed the finding of a prevailing LF component in resting conditions. (3) In the 10 control subjects maximal dynamic exercise induced an increase in LF which outlasted the cessation of exercise up to 24 h, suggesting a persistent sympathetic activation. (4) Passive tilt, a manoeuvre which enhances sympathetic drive, produced a greater enhancement of the LF component in trained athletes than in control subjects. The cardiac sympathetic excitation outlasting heavy dynamic exercise may explain the coexistence of training bradycardia with signs of enhanced sympathetic activity in trained champion athletes.
Article
Coronary heart disease (CHD) and cardiac sudden death (CSD) incidence accelerates after menopause, but the incidence is lower in physically active versus less active women. Low heart rate variability (HRV) is a risk factor for CHD and CSD. The purpose of the present investigation was to test the hypothesis that HRV at rest is greater in physically active compared with less active postmenopausal women. If true, we further hypothesized that the greater HRV in the physically active women would be closely associated with an elevated spontaneous cardiac baroreflex sensitivity (SBRS). HRV (both time and frequency domain measures) and SBRS (sequence method) were measured during 5-min periods of controlled frequency breathing (15 breaths/min) in the supine, sitting, and standing postures in 9 physically active postmenopausal women (age = 53 +/- 1 yr) and 11 age-matched controls (age = 56 +/- 2 yr). Body weight, body mass index, and body fat percentage were lower (P < 0.01) and maximal oxygen uptake was higher (P < 0.01) in the physically active group. The standard deviation of the R-R intervals (time domain measure) was higher in all postures in the active women (P < 0.05) as were the high-frequency, low-frequency, and total power of HRV. SBRS also was higher (P < 0.05) in the physically active women in all postures and accounted for approximately 70% of the variance in the high-frequency power of HRV (P < 0.05). The results of the present investigation indicate that physically active postmenopausal women demonstrate higher levels of HRV compared with age-matched, less active women. Furthermore, SBRS accounted for the majority of the variance in the high-frequency power of HRV, suggesting the possibility of a mechanistic link with cardiac vagal modulation of heart rate. Our findings may provide insight into a possible cardioprotective mechanism in physically active postmenopausal women.
Article
Heart rate variability (HRV) (SD of the RR interval), an index of parasympathetic tone, was measured at rest and during exercise in 13 healthy older men (age 60 to 82 years) and 11 healthy young men (age 24 to 32 years) before and after 6 months of aerobic exercise training. Before exercise training, the older subjects had a 47% lower HRV at rest compared with the young subjects (31 +/- 5 ms vs 58 +/- 4 ms, p = 0.0002). During peak exercise, the older subjects had less parasympathetic withdrawal than the young subjects (-45% vs -84%, p = 0.0001). Six months of intensive aerobic exercise training increased maximum oxygen consumption by 21% in the older group and 17% in the young group (analysis of variance: overall training effect, p = 0.0001; training effect in young vs old, p = NS). Training decreased the heart rate at rest in both the older (-9 beats/min) and the young groups (-5 beats/min, before vs after, p = 0.0001). Exercise training increased HRV at rest (p = 0.009) by 68% in the older subjects (31 +/- 5 ms to 52 +/- 8 ms) and by 17% in the young subjects (58 +/- 4 ms to 68 +/- 6 ms). Exercise training increases parasympathetic tone at rest in both the healthy older and young men, which may contribute to the reduction in mortality associated with regular exercise.
Article
The purpose of this study was to determine whether resting heart rate variability (HRV) is reproducible with short sampling measurement periods using an office-based personal computer measurement system. Eight healthy active women participated in ECG analyses on 2 days within 1 week under controlled environmental and physiological conditions. After they rested for 10 minutes, a 10-min ECG was recorded. HRV was determined from a 2.5- and 5-min sample period using both time domain variables (meanRR and SDNN) and frequency domain variables (LF, HF, LF:HF). Repeated measures ANOVA found no significant differences between Day 1 and Day 2 for either sampling period (p > or = 0.23). For both the 2.5- and 5-min sampling periods, the intraclass correlations between days for the time domain variables showed good reproducibility (R = 0.86-0.90). The reproducibility of the frequency domain variable was only average (R = 0.67-0.96), with the LF:HF ratio yielding the higher R values.
Article
Reduced heart rate variability is associated with an unfavourable prognosis in patients with ischaemic heart disease. Whether physical training can modify this risk factor is not definitely proven. Our hypothesis was that training might increase both physical capacity and heart rate variability in elderly patients recovering from an acute coronary event, i.e. acute myocardial infarction (n=38) or an episode of unstable angina (n=27). METHODS and 24 h ambulatory ECG recordings were obtained from 65 patients randomized to either a 3 months supervised outpatient group training programme 50 min three times a week (n=29) or to a control group (n=36). The two groups were well balanced as regards demographic data and pharmacological treatment at the time of randomization. Body mass index and pharmacological therapy remained unchanged during the study. Heart rate variability was analysed in the time and frequency domains. At the 3 month follow-up, exercise tolerance had increased from 103 to 120 W in the training group (P<0.001), and from 102 to 106 W in the control group (ns). The time-domain heart rate variability measures SDNN (standard deviation of all filtered RR intervals over the analysed time period) and SDANN (standard deviation of the means of all filtered RR intervals for all 5 min epochs of the analysed time period) increased significantly during the daytime in the training group (P<0.01 and P<0.05, respectively), but not in the control group. A significant improvement in night-time heart rate variability was observed among controls. There was a statistically significant correlation (P<0.05) between changes in 24 h overall power (frequency domain measure) and changes in maximal exercise capacity in the training group. A regular aerobic group training programme after an acute coronary event can significantly improve exercise capacity and modify heart rate variability in a prognostically favourable direction in elderly low-to-intermediate risk patients, recovering from an acute coronary event.
Article
To investigate the effects on cardiac autonomic control after a competitive cross-country skiing season, 9 females and 8 males, 16-19 years old, performed tilt-table heart rate variability (HRV) recordings and incremental treadmill tests before (August), and after (April the following year) the most intensive period of training and competition. Spectral analysis of HRV showed increased total variability at rest and reduced low frequency variability in the tilted position (LFtilt) at the second test (P<0.05). The female subgroup showed consistently higher high frequency (HF) and total heart rate variability than males. Total run time (RunT) increased from 18.5+/-1.9 min to 19.4+/-1.7 min (mean+/-SD) in the entire group (P<0.05), while VO2max only showed a non-significant increase (0.05<P<0.10). Submaximal heart rates (HRsubm) were reduced by an average of 4 beats (P<0.01) but maximal HR was unchanged. Performance data suggest a positive training effect. Following training, the increased total HRV the reduced LFtilt (both at rest), and the lower submaximal heart rates indicate an altered control of heart rate both at rest and during exercise. The consistently higher HF and total variability in the females indicate an increased parasympathetic activity in females compared with males.
Article
Altered variability in the cardiovascular system is associated with a range of cardiovascular diseases and increased mortality. Because blood pressure and heart rate show distinct low-frequency oscillations that appear to be affected by either vagal or sympathetic activity, it has been hoped that measurement of the strength of these oscillations could be used as an index of autonomic tone and thus form the basis of a diagnostic test. This review focuses on recent research that has examined the fundamental origin of variability associated with respiration and a slow oscillation at 0.1 Hz in the human. A new hypothesis is proposed to account for the slow oscillation in heart rate and blood pressure that incorporates components of the central nervous system, other reflex pathways regulating sympathetic activity, and resonance in the baroreflex control of blood pressure. Whereas it is clear that sympathetic activity and arterial baroreflexes are critical elements in producing cardiovascular variability, there is also evidence that other factors, including the ability of the vasculature to respond to sympathetic activity, appear to play a role in determining the strength of oscillations. Given the potential impact of other nonbaroreflex or nonautonomic pathways in affecting cardiovascular variability, it is proposed that one must use care in relating changes in the strength of an oscillation in blood pressure and heart rate as definitively due to a change in autonomic control.
Article
The effects of an intense 8-wk aerobic training program on cardiovascular responses at rest and during exercise, including heart rate variability (HRV) as an expression of autonomic modulation, were evaluated in subjects over 70 yr (mean: 73.9 +/- 3.5 yr). Before and after training in 7 men and 8 women: a) heart rate (HR), blood pressures (BPs), pulse pressure (PP), and oxygen uptake were measured at rest, during, and after exhausting incremental exercise; b) HRV power spectra were calculated at rest in supine and sitting, and during and after two submaximal constant loads (5 min). Power in low-frequency (LF, 0.04-0.15 Hz) and high-frequency (HF, >0.15 Hz) bands were expressed as a percent of total power minus power < 0.04 Hz. After training: a) at rest HR and HRV parameters (in both body positions) were unchanged, whereas BPs decreased; b) peak cycle resistance and oxygen consumption increased by 25% and 18%, respectively, but no change in maximal HR and BPs were found; c) during submaximal loads HR was unchanged at the same metabolic demand, whereas SBP and DBP were lower than before at low loads whereas PP was unchanged. LF power decreased and HF increased at oxygen uptakes above about 0.7 L.min-1 similarly before and after training; and d) recovery of all parameters was similar to pretraining and complete after 10 min The increase in exercise capacity without changes in cardiovascular parameters suggests that 8 wk of aerobic training augmented peripheral gas exchange but not delivery to muscle. The lack of effect on HRV indicates that the improvements in aerobic power and cardiac autonomic modulation, at least in subjects over 70 yr, are dissociated. Moreover, the metabolic demand seems to be the main factor for the changes in HRV power spectra that occur during exercise.
Article
We investigated the effect of exercise on heart rate variability by analysing the heart rate power spectrum prior to, and 1 and 72 h following, an interval training session. Subjects initially performed a graded test to exhaustion to determine maximal oxygen uptake (VO(2) max) and the running speed at which VO(2) max was first attained (vVO(2) max). The training session was completed on a separate day and comprised six 800 m runs at 1 km x h (-1) below vVO(2) max. Prior to the training session (pre), 1 h following the training session (+ 1h), and 72 h following the training session (+ 72 h), subjects sat quietly in the laboratory for 20 min whilst breathing frequency was maintained at 12 breath x min (-1). Cardiac cycle R-R interval data were collected over the final 5 min of each 20 min period and analysed by means of autoregressive power spectral analysis to determine the high frequency (HF) and low frequency (LF) components of heart rate variability. Heart rate was higher, and the standard deviation of the R-R intervals was lower, at + 1 h than for pre or + 72 h (p < 0.05). The HF and the LF components of heart rate variability were also lower (p < 0.05) for + 1 h than for pre or + 72 h when the data were expressed in ms(2). However, no changes in the LF:HF ratio were observed, and the changes in the HF and LF components disappeared when the data were expressed as a fraction of the total power. Whilst these findings illustrate the importance of controlling the timing of exercise prior to the determination of heart rate variability, the time course of the post-exercise heart rate variability response remains to be quantified.