Post-exercise Parasympathetic Reactivation Research Articles

The effects of a 6-hour ultra-endurance run on postexercise parasympathetic reactivation responses.

Alterations in cardiac autonomic control reflecting depressed parasympathetic activity have been previously reported after ultra-endurance events at rest and during dynamic tasks assessing cardiac autonomic responsiveness. This study investigated the impact of a 6-hour ultra-endurance run on parasympathetic reactivation indices, using an exercise-recovery transition approach. Nine trained runners (VO<inf>2max</inf> 67±12 mL/kg/min) completed a 6-hour run (EXP) whilst other six runners (VO<inf>2max</inf> 66±10 mL/kg/min) served as a control (CON). Before (PRE) and after the run/control period (POST) participants completed standard cardiac autonomic activity assessments. Postexercise parasympathetic reactivation was assessed by means of heart rate recovery (HRR) and vagal-related time-domain HRV indices. HR was increased at rest (P<0.001, ES=3.53), during exercise (P<0.05, ES=0.38) and recovery (all P<0.001, ES from 0.91 to 1.46) at POST in EXP and not in CON (all P>0.05). At POST vagal-related HRV indices were significantly decreased at rest (P<0.001, ES from -2.38 to -3.54) and during postexercise recovery (all P<0.001, ES from -0.97 to -1.58) only in EXP. HRR at 30 and 60 s were markedly reduced at POST in EXP both when expressed in bpm and normalized for the exercising HR (all P<0.001, ES from -1.21 to -1.74). A 6-hour run markedly impacted upon postexercise parasympathetic reactivation responses causing a decrease in HRR and HRV recovery indices. For the first time, this study attested blunted postexercise parasympathetic reactivation responses following an acute bout of ultra-endurance exercise.

Impact of sodium citrate ingestion during recovery after strenuous exercise in the heat on heart rate variability: A randomized, crossover study

Changes in hydration status influence plasma volume (PV) which is associated with post‐exercise parasympathetic reactivation. The present study hypothesized that, after dehydrating cycling exercise in the heat (DE), stimulation of PV expansion with sodium citrate (CIT) supplementation would promote heart rate variability (HRV) recovery in endurance‐trained men. Twelve participants lost 4% of body mass during DE. During subsequent 16‐h recovery, participants consumed water ad libitum (CIT =5.5‐L, PLC =5.1‐L) and ate prescribed food supplemented with CIT or placebo in a randomized, double‐blind, crossover manner. Relative changes in PV were assessed across DE and 16‐h recovery. HRV was analyzed before and 16 h after DE in three conditions for altogether four 5‐min periods: supine in a thermoneutral environment, supine in the heat (32°C, 46% relative humidity; 2 periods), and standing in the heat. A larger expansion of PV across 16‐h recovery occurred in CIT compared to placebo trial (p < 0.0001). However, no between‐trial differences appeared in HRV parameters (lnRMSSD, lnSDNN, lnLF/HF) in any 5‐min period analyzed before or 16 h after DE (in all cases p > 0.05). Increases in HR (p < 0.001) and lnLF/HF (p = 0.005) and decreases in lnRMSSD (p < 0.001) and lnSDNN (p < 0.001) occurred following DE in both trials. Larger PV expansion induced by CIT supplementation after DE does not improve recovery of HRV at rest and has no influence on HRV responsiveness in endurance‐trained men.

Post-exercise heart rate recovery and parasympathetic reactivation are comparable between prepubertal boys and well-trained adult male endurance athletes.

PurposeThis study tested the hypothesis that prepubertal boys, but not untrained men, would exhibit a similar post-exercise parasympathetic reactivation as well-trained adult male endurance athletes. MethodsTwelve prepubertal boys (12.3 ± 1.6 years), 14 untrained men (21.8 ± 2.2 years) and 16 well-trained adult male endurance athletes (24.5 ± 4.8 years) completed an incremental maximal run field test on a track. Immediately after exercise completion, heart rate recovery (HRR) was assessed in the supine position for 5 min. Heart rate variability was analyzed in the time domain, and log-transformed values of the root mean square of successive differences in heart beats (Ln RMSSD30) were calculated over consecutive 30 s windows.ResultsPrepubertal children and well-trained adult endurance athletes showed significantly faster HRR than untrained adults from 30 s post-exercise until the end of recovery (p < 0.05). Ln RMSSD30 was significantly higher in prepubertal children and athletes than untrained adults over the post-exercise time interval 60–150 s (p < 0.05). No significant differences were observed for HRR and Ln RMSSD30 between prepubertal children and athletes.ConclusionPrepubertal children and well-trained adult endurance athletes exhibited comparable and faster HRR and parasympathetic reactivation than untrained adults following maximal exercise. This indirectly suggests that oxidative profile may be preserved by exercise training during growth and maturation to offset the decline in post-exercise HRR, parasympathetic reactivation and aspects of metabolic health.

The Impact of Functional Overreaching on Post-exercise Parasympathetic Reactivation in Runners.

While post-exercise heart rate (HR) variability (HRV) has been shown to increase in response to training leading to improvements in performance, the effect of training leading to decrements in performance (i.e., overreaching) on this parameter has been largely ignored. This study evaluated the effect of heavy training leading to performance decrements on sub-maximal post-exercise HRV. Running performance [5 km treadmill time-trial (5TTT)], post-exercise HRV [root-mean-square difference of successive normal R-R intervals (RMSSD)] and measures of subjective training tolerance (Daily Analysis of Life Demands for Athletes “worse than normal” scores) were assessed in 11 male runners following 1 week of light training (LT), 2 weeks of heavy training (HT) and a 10 day taper (T). Post-exercise RMSSD was assessed following 5 min of running exercise at an individualised speed eliciting 85% of peak HR. Time to complete 5TTT likely increased following HT (ES = 0.14 ± 0.03; p < 0.001), and then almost certainly decreased following T (ES = −0.30 ± 0.07; p < 0.001). Subjective training tolerance worsened after HT (ES = −2.54 ± 0.62; p = 0.001) and improved after T (ES = 2.16 ± 0.64; p = 0.004). In comparison to LT, post-exercise RMSSD likely increased at HT (ES = 0.65 ± 0.55; p = 0.06), and likely decreased at T (ES = −0.69 ± 0.45; p = 0.02). A moderate within-subject correlation was found between 5TTT and post-exercise RMSSD (r = 0.47 ± 0.36; p = 0.03). Increased post-exercise RMSSD following HT demonstrated heightened post-exercise parasympathetic modulation in functionally overreached athletes. Heightened post-exercise RMSSD in this context appears paradoxical given this parameter also increases in response to improvements in performance. Thus, additional measures such as subjective training tolerance are required to interpret changes in post-exercise RMSSD.

Intrarater reliability of different methods of heart rate variability threshold analysis and postexercise parasympathetic reactivation in young women

Abstract Objective: To evaluate the reliability of HRVT and postexercise parasympathetic reactivation analysis after a submaximal exercise test in young women. Methods: Twenty-four young women [21.1 (20.1, 24.7) years; 21.4 (20.1, 23.1) kg/m2] underwent three incremental exercise tests on a treadmill on occasions separated by 48 h. R-R intervals were continuously recorded during the incremental tests and throughout 5 min of post-exercise active recovery for HRVT and parasympathetic reactivation analysis, respectively. HRVT was identified using two methods: a) the intensity where no significant reduction of SD1 HRV index was identified by visual inspection of the graphic (HRVTvisual), b) the first stage to present SD1 value < 3ms (HRVT3ms). Postexercise parasympathetic reactivation was assessed at each minute during five minutes of recovery using SD1 and r-MSSD indexes. Absolute and relative reliability were assessed using the coefficient of variation (CV) and the intraclass correlation coefficient (ICC), respectively. Results: Good (ICC = 0.81, CV = 17.3) and excellent (ICC = 0.90, CV = 4.6) reliability were observed for HRVT3ms and HRVTvisual, respectively. On the postexercise period, good reliability was observed for both SD1 (ICC = 0.82-89, CV = 22.1-28.9) and r-MSSD (ICC = 0.82-89, CV = 21.1-28.6), with a high correlation between indexes in all-time points of analysis (r = 0.96-0.99). Conclusions: HRVT may be reproducibly assessed in women, mainly when HRVTvisual is used for analysis. In addition, SD1 and r-MSSD provide reliable and redundant measures of postexercise parasympathetic reactivation.

Influence of Body Composition on Post-Exercise Parasympathetic Reactivation of Firefighter Recruits.

Firefighters have a sustained risk for experiencing a sudden cardiac event after completing a fire call. Heart rate recovery (HRR) can be utilized to characterize autonomic nervous system (ANS) recovery and has been linked to cardiac events. Research suggests that body composition influences post-exercise HRR responses in non-firefighter populations. The purpose of this study was to examine the influence of body mass index (BMI), waist circumference (WC), and percent body fat (BF) on the HRR response of firefighter recruits. BMI (kg·m−2), WC (cm), and BF (%) data from 57 firefighter recruits were collected. HRR (b·min−1) data were collected at completion (HR0), as well as 15 (HR15), 30 (HR30), 45 (HR45), 60 (HR60), 120 (HR120), and 180 (HR180) seconds following a submaximal step test, and commonly utilized clinical HRR indices were calculated (ΔHRR30, ΔHRR60, ΔHRR120, and ΔHRR180). After controlling for sex, linear mixed regression models did not identify significant interactions between body composition (ps > 0.05) and HRR response across time. However, significant (ps < 0.05) indirect semi-partial correlations were identified between BF and ΔHRR30 (rsp = −0.31) and ΔHRR60 (rsp = −0.27), respectively. Reducing overall BF (vs. BMI or WC) should be prioritized to improve the post-exercise ANS recovery of firefighter recruits.

Comparison of Heart Rate Variability Responses to Varying Resistance Exercise Volume-Loads

ABSTRACT Purpose: The aim of this study was to compare the effects of low ([LV]; 4 total sets), moderate ([MV]; 8 total sets), and high set volumes ([HV]; 12 total sets) in acute full-body resistance exercise sessions on post-exercise parasympathetic reactivation measured using RMSSD. Methods: Ten resistance-trained participants (25.8 ± 6.8 yr., 173.4 ± 10.6 cm, 75.4 ± 9.9 kg) performed three resistance exercise sessions. During each session, heart rate variability (HRV) was measured pre- and for 30 min post-exercise, divided into 5-min segments stabilization, Post5-10, Post10-15, Post15-20, Post20-25, and Post25-30. Repeated-measures ANOVA was used to assess differences within and between pre-post exercise natural logarithm RMSSD (LnRMSSD) values. To assess the initial change in LnRMSSD, the delta percent change (ΔLnRMSSD) from pre-exercise to Post5-10 (ΔLnRMSSDpre-post) was calculated for each session. The ΔLnRMSSD was also calculated between Post5-10 and Post25-30 (ΔLnRMSSDpost5-30) to assess recovery. Results: Significant differences were observed between sessions and when comparing pre-exercise values to all post-exercise times across sessions (p ≤ .05). The LV session resulted in significantly higher mean LnRMSSD value (3.62) post-exercise compared to both the MV (3.11, effect size [ES] = 3.77) and HV (3.02, ES = 3.92) sessions while the MV and HV sessions produced similar responses. Across sessions no return to baseline occurred and when comparing sessions, no significant differences were found in ΔLnRMSSDpre-post or ΔLnRMSSDpost5-30. Conclusion: Acute bouts of full-body resistance exercise can cause similar reductions in LnRMSSD from pre-exercise levels and can delay parasympathetic reactivation back to baseline values during the same 30-min recovery period despite differences in set volume.

Influence of exercise modality on cardiac parasympathetic and sympathetic indices during post-exercise recovery

ObjectivesThis study investigated indirect measures of post-exercise parasympathetic reactivation (using heart-rate-variability, HRV) and sympathetic withdrawal (using systolic-time-intervals, STI) following upper- and lower-body exercise. DesignRandomized, counter-balanced, crossover. Methods13 males (age 26.4±4.7years) performed maximal arm-cranking (MAX-ARM) and leg-cycling (MAX-LEG). Subsequently, participants undertook separate 8-min bouts of submaximal HR-matched exercise of each mode (ARM and LEG). HRV (including natural-logarithm of root-mean-square-of-successive-differences, Ln-RMSSD) and STI (including pre-ejection-period, PEP) were assessed throughout 10-min seated recovery. ResultsPeak-HR was higher (p=0.001) during MAX-LEG (182±7beatsmin−1) compared with MAX-ARM (171±12beatsmin−1), while HR (p<0.001) and Ln-RMSSD (p=0.010) recovered more rapidly following MAX-ARM. PEP recovery was similar between maximal bouts (p=0.106). HR during submaximal exercise was 146±7 (LEG) and 144±8beatsmin−1 (LEG) (p=0.139). Recovery of HR and Ln-RMSSD was also similar between submaximal modalities, remaining below baseline throughout recovery (p<0.001). PEP was similar during submaximal exercise (LEG 70±6ms; ARM 72±9ms; p=0.471) although recovery was slower following ARM (p=0.021), with differences apparent from 1- to 10-min recovery (p≤0.036). By 10-min post-exercise, PEP recovered to baseline (132±21ms) following LEG (130±21ms; p=0.143), but not ARM (121±17ms; p=0.001). ConclusionsCompared with submaximal lower-body exercise, HR-matched upper-body exercise elicited a similar recovery of HR and HRV indices of parasympathetic reactivation, but delayed recovery of PEP (reflecting sympathetic withdrawal). Exercise modality appears to influence post-exercise parasympathetic reactivation and sympathetic withdrawal in an intensity-dependent manner. These results highlight the need for test standardization and may be relevant to multi-discipline athletes and in clinical applications with varying modes of exercise testing.

Longer exercise duration delays post-exercise recovery of cardiac parasympathetic but not sympathetic indices.

This study investigated non-invasive indices of post-exercise parasympathetic reactivation (using heart rate variability, HRV) and sympathetic withdrawal (using systolic time intervals, STI) following different exercise durations. 13 healthy males (age 26.4±4.7years) cycled at 70% heart rate (HR) reserve for two durations-8 min (SHORT) and 32 min (LONG)-on separate occasions: HRV (including natural logarithm of root mean square of successive differences, Ln-RMSSD) and STI (including pre-ejection period, PEP) were assessed throughout 10 min seated recovery. Exercise HR was similar between SHORT and LONG (146±7 and 147±6 bmin-1, respectively; p=0.173), as was HR deceleration during 10 min recovery (p=0.199). HR remained elevated above baseline (p<0.001) throughout recovery for both trials (SHORT 82±13 bmin-1; LONG 86±10 bmin-1, at 10 min post-exercise). Ln-RMSSD was similar at end-exercise between trials (SHORT 1.10±0.30ms; LONG 1.05±0.73ms; p=0.656), though it recovered more rapidly following SHORT (p=0.010), with differences apparent from 1 min (SHORT 2.29±1.08ms; LONG 1.85±0.82ms; p=0.005) to 10 min post-exercise (SHORT 2.89±0.80ms; LONG 2.46±0.70ms; p=0.007). Ln-RMSSD remained suppressed below baseline throughout recovery following both trials (p<0.001). PEP was the same at end exercise for both trials (70±6ms), with exercise duration having no effect on recovery (p=0.659). By 10 min post-exercise, PEP increased to 130±21ms (SHORT) and 131±20ms (LONG), which was similar to baseline (p≥0.143). Prolonged exercise duration attenuated the recovery of HRV indices of parasympathetic reactivation, but did not influence STI indices of sympathetic withdrawal. Therefore, duration must be considered when investigating post-exercise HRV. Monitoring these measures simultaneously can provide insights not revealed by underlying HR or either measure alone.

Effects of Body Positions on Heart Rate Variability and Hemodynamics after a 3-min Step Test in Dancers

It is well documented that autonomic nervous modulation is adapted to acute change of body position. The purpose of this study was to investigate the acute effect of body position on short term heart rate variability (HRV) and hemodynamic changes after a 3-min step test. Twenty-one university dancers (20.1 ± 0.7 years) were voluntarily participated in this study. Participants performed a 3-min step test in 3 occasions at the same time of the day with at least 24 h apart. Pre- and post-exercise 15-min resting HRV and blood pressure were measured in supine, sitting, or standing positions before and after a 3-min step test. Portable heart rate monitor (Polar RS800CX) was used to collect the series of heart rate beats throughout the experiment. Result showed no significant difference of cardiorespiratory fitness indices among the testing conditions. The HRV indices in pre-and post-exercise records showed differences between standing and supine positions. For the percentage change in the HRV indices, the result of SDHR index showed significantly increase in sitting position. The indices of rMSSD, HFP, SD1, ApEn, and SampEn were significantly decreased in standing position, compared with sitting or supine position. For pre- and post-exercise hemodynamic measurements, diastolic blood pressure and mean arterial pressure during standing was significantly higher than supine and sitting positions. In addition, pulse pressure before and after exercise was significant low during standing position. No significant difference was found in percentage change of all hemodynamic variables. Standing position increased post-exercise sympathetic activation after a 3-min step test. We conclude that decrease in post-exercise parasympathetic reactivation during standing position and no position effect on hemodynamic functions after a 3-min step exercise in un iversity dancers.

Autonomic cardiovascular modulation in masters and young cyclists following high-intensity interval training.

This study aimed at examining the autonomic cardiovascular modulation in well-trained masters and young cyclists following high-intensity interval training (HIT). Nine masters (age 55.6 ± 5.0years) and eight young cyclists (age 25.9 ± 3.0years) completed a HIT protocol of 6 x 30sec at 175% of peak power output, with 4.5-min' rest between efforts. Immediately following HIT, heart rate and R-R intervals were monitored for 30-min during passive supine recovery. Autonomic modulation was examined by i) heart rate recovery in the first 60-sec of recovery (HRR60); ii) the time constant of the 30-min heart rate recovery curve (HRRτ); iii) the time course of the root mean square for successive 30-sec R-R interval (RMSSD30); and iv) time and frequency domain analyses of subsequent 5-min R-R interval segments. No significant between-group differences were observed for HRR60 (P = 0.096) or HRRτ (P = 0.617). However, a significant interaction effect was found for RMSSD30 (P = 0.021), with the master cyclists showing higher RMSSD30 values following HIT. Similar results were observed in the time and frequency domain analyses with significant interaction effects found for the natural logarithm of the RMSSD (P = 0.008), normalised low-frequency power (P = 0.016) and natural logarithm of high-frequency power (P = 0.012). Following high-intensity interval training, master cyclists demonstrated greater post-exercise parasympathetic reactivation compared to young cyclists, indicating that physical training at older ages has significant effects on autonomic function.

Correction: Caffeine Ingestion Increases Estimated Glycolytic Metabolism during Taekwondo Combat Simulation but Does Not Improve Performance or Parasympathetic Reactivation

[This corrects the article DOI: 10.1371/journal.pone.0142078.].

Parasympathetic Reactivation Is Improved After Maximal Cycling Exercise In Immersion As Compared To Dryland Condition

PURPOSE: This aim of this study was to compare post-exercise parasympathetic reactivation after maximal incremental exercise performed at the same external power output (Pext) on dryland ergocycle (DE) vs. immersible ergocycle (IE). METHODS: Fifteen young healthy participants (30±7 years, 13 males and 2 females) performed in a random order an incremental maximal exercise tests on DE and another one on IE. On DE, the initial external power was 25 W and was increased by 25 W/min. On IE, initial external power was 40 rpm and was increased by 10 rpm until 70 rpm and thereafter by 5 rpm until exhaustion. Gas exchange and heart rate (HR) were measured continuously during exercise and 5-min recovery period. Parasympathetic reactivation parameters (ie: T30, τ, ΔHR from 10 to 300 sec) were compared during the IE and DE recovery. RESULTS: During the IE recovery, parasympathetic reactivation in the short-term phase was more predominant (ie: T30, HRR at Δ10, Δ20, Δ30, Δ60 sec, P<0.05), but similar in the long-term phase (HRR at Δ120, Δ180, Δ240 and Δ300 sec, P>0.05) as compared to the DE condition. CONCLUSION: Our study showed that recovery in immersion to the chest level following maximal exercise can accelerate parasympathetic reactivation during the short-term phase, as compared with recovery after maximal exercise on DE in healthy young participants.

The effect of different water immersion temperatures on post-exercise parasympathetic reactivation.

PurposeWe evaluated the effect of different water immersion (WI) temperatures on post-exercise cardiac parasympathetic reactivation.MethodsEight young, physically active men participated in four experimental conditions composed of resting (REST), exercise session (resistance and endurance exercises), post-exercise recovery strategies, including 15 min of WI at 15°C (CWI), 28°C (TWI), 38°C (HWI) or control (CTRL, seated at room temperature), followed by passive resting. The following indices were assessed before and during WI, 30 min post-WI and 4 hours post-exercise: mean R-R (mR-R), the natural logarithm (ln) of the square root of the mean of the sum of the squares of differences between adjacent normal R–R (ln rMSSD) and the ln of instantaneous beat-to-beat variability (ln SD1).ResultsThe results showed that during WI mRR was reduced for CTRL, TWI and HWI versus REST, and ln rMSSD and ln SD1 were reduced for TWI and HWI versus REST. During post-WI, mRR, ln rMSSD and ln SD1 were reduced for HWI versus REST, and mRR values for CWI were higher versus CTRL. Four hours post exercise, mRR was reduced for HWI versus REST, although no difference was observed among conditions.ConclusionsWe conclude that CWI accelerates, while HWI blunts post-exercise parasympathetic reactivation, but these recovery strategies are short-lasting and not evident 4 hours after the exercise session.

Effect of Acute Hypoxia on Post-Exercise Parasympathetic Reactivation in Healthy Men

In this study we assessed the effect of acute hypoxia on post-exercise parasympathetic reactivation inferred from heart rate (HR) recovery (HRR) and HR variability (HRV) indices. Ten healthy males participated in this study. Following 10 min of seated rest, participants performed 5 min of submaximal running at the speed associated with the first ventilatory threshold (Sub) followed by a 20-s all-out supramaximal sprint (Supra). Both Sub and Supra runs were immediately followed by 15 min of seated passive recovery. The resting and exercise sequence were performed in both normoxia (N) and normobaric hypoxia (H; FiO2 = 15.4%). HRR indices (e.g., heart beats recovered in the first minute after exercise cessation, HRR60s) and vagal-related HRV indices [i.e., natural logarithm of the square root of the mean of the sum of the squared differences between adjacent normal R–R intervals (Ln rMSSD)] were calculated for both conditions. Difference in the changes between N and H for all HR-derived indices were also calculated for both Sub and Supra. HRR60s was greater in N compared with H following Sub only (60 ± 14 vs. 52 ± 19 beats min−1, P = 0.016). Ln rMSSD was greater in N compared with H (post Sub: 3.60 ± 0.45 vs. 3.28 ± 0.44 ms in N and H, respectively, and post Supra: 2.66 ± 0.54 vs. 2.65 ± 0.63 ms, main condition effect P = 0.02). When comparing the difference in the changes, hypoxia decreased HRR60s (−14.3% ± 17.2 vs. 5.2% ± 19.3; following Sub and Supra, respectively; P = 0.03) and Ln rMSSD (−8.6% ± 7.0 vs. 2.0% ± 13.3, following Sub and Supra, respectively; P = 0.08, Cohen’s effect size = 0.62) more following Sub than Supra. While hypoxia may delay parasympathetic reactivation following submaximal exercise, its effect is not apparent following supramaximal exercise. This may suggest that the effect of blood O2 partial pressure on parasympathetic reactivation is limited under heightened sympathetic activation.

Effect of maturation on hemodynamic and autonomic control recovery following maximal running exercise in highly trained young soccer players.

The purpose of this study was to examine the effect of maturation on post-exercise hemodynamic and autonomic responses. Fifty-five highly trained young male soccer players (12–18 years) classified as pre-, circum-, or post-peak height velocity (PHV) performed a graded running test to exhaustion on a treadmill. Before (Pre) and after (5th–10th min, Post) exercise, heart rate (HR), stroke volume (SV), cardiac output (CO), arterial pressure (AP), and total peripheral resistance (TPR) were monitored. Parasympathetic (high frequency [HFRR] of HR variability (HRV) and baroreflex sensitivity [Ln BRS]) and sympathetic activity (low frequency [LFSAP] of systolic AP variability) were estimated. Post-exercise blood lactate [La]b, the HR recovery (HRR) time constant, and parasympathetic reactivation (time-varying HRV analysis) were assessed. In all three groups, exercise resulted in increased HR, CO, AP, and LFSAP (P < 0.001), decreased SV, HFRR, and Ln BRS (all P < 0.001), and no change in TPR (P = 0.98). There was no “maturation × time” interaction for any of the hemodynamic or autonomic variables (all P > 0.22). After exercise, pre-PHV players displayed lower SV, CO, and [La]b, faster HRR and greater parasympathetic reactivation compared with circum- and post-PHV players. Multiple regression analysis showed that lean muscle mass, [La]b, and Pre parasympathetic activity were the strongest predictors of HRR (r2 = 0.62, P < 0.001). While pre-PHV players displayed a faster HRR and greater post-exercise parasympathetic reactivation, maturation had little influence on the hemodynamic and autonomic responses following maximal running exercise. HRR relates to lean muscle mass, blood acidosis, and intrinsic parasympathetic function, with less evident impact of post-exercise autonomic function.

Effect of cold or thermoneutral water immersion on post-exercise heart rate recovery and heart rate variability indices

This study aimed to investigate the effect of cold and thermoneutral water immersion on post-exercise parasympathetic reactivation, inferred from heart rate (HR) recovery (HRR) and HR variability (HRV) indices. Twelve men performed, on three separate occasions, an intermittent exercise bout (all-out 30-s Wingate test, 5 min seated recovery, followed by 5 min of submaximal running exercise), randomly followed by 5 min of passive (seated) recovery under either cold (CWI), thermoneutral water immersion (TWI) or control (CON) conditions. HRR indices (e.g., heart beats recovered in the first minute after exercise cessation, HRR 60 s) and vagal-related HRV indices (i.e., natural logarithm of the square root of the mean of the sum of the squares of differences between adjacent normal R–R intervals (Ln rMSSD)) were calculated for the three recovery conditions. HRR 60 s was faster in water immersion compared with CON conditions [30 ± 9 beats min − 1 for CON vs. 43 ± 10 beats min − 1 for TWI ( P = 0.003) and 40 ± 13 beats min − 1 for CWI ( P = 0.017)], while no difference was found between CWI and TWI ( P = 0.763). Ln rMSSD was higher in CWI (2.32 ± 0.67 ms) compared with CON (1.98 ± 0.74 ms, P = 0.05) and TWI (2.01 ± 0.61 ms, P = 0.08; aES = 1.07) conditions, with no difference between CON and TWI ( P = 0.964). Water immersion is a simple and efficient means of immediately triggering post-exercise parasympathetic activity, with colder immersion temperatures likely to be more effective at increasing parasympathetic activity.

Influence of cold water face immersion on post-exercise parasympathetic reactivation

The aim of the present study was to investigate the effect of cold water face immersion on post-exercise parasympathetic reactivation, inferred from heart rate (HR) recovery (HRR) and HR variability (HRV) indices. Thirteen men performed, on two different occasions, an intermittent exercise (i.e., an all-out 30-s Wingate test followed by a 5-min run at 45% of the speed reached at the end of the 30-15 Intermittent Fitness test, interspersed with 5 min of seated recovery), randomly followed by 5 min of passive (seated) recovery with either cold water face immersion (CWFI) or control (CON). HR was recorded beat-to-beat and vagal-related HRV indices (i.e., natural logarithm of the high-frequency band, LnHF, and natural logarithm of the square root of the mean sum of squared differences between adjacent normal R-R intervals, Ln rMSSD) and HRR (e.g., heart beats recovered in the first minute after exercise cessation) were calculated for both recovery conditions. Parasympathetic reactivation was faster for the CWFI condition, as indicated by higher LnHF (P = 0.004), Ln rMSSD (P = 0.026) and HRR (P = 0.002) values for the CWFI compared with the CON condition. Cold water face immersion appears to be a simple and efficient means of immediately accelerating post-exercise parasympathetic reactivation.

Exercise-induced plasma volume expansion and post-exercise parasympathetic reactivation

The purpose of this study was to investigate the effect of exercise-induced plasma volume expansion on post-exercise parasympathetic reactivation. Before (D(0)) and 2 days after (D(+2)) a supramaximal exercise session, 11 men (21.4 +/- 2.6 years and BMI = 23.0 +/- 1.4) performed 6-min of submaximal running where heart rate (HR) recovery (HRR) and HR variability (HRV) indices were calculated during the first 10 min of recovery. Relative plasma volume changes (PV) were calculated using changes in hematocrit and hemoglobin measured over consecutive mornings from D(0) to D(+2). Parasympathetic reactivation was evaluated through HRR and vagal-related indexes calculated during a stationary period of recovery. Compared with D(0), PV (+4.8%, P < 0.01) and all vagal-related HRV indices were significantly higher at D(+2) (all P < 0.05). HRR was not different between trials. Changes in HRV indices, but not HRR, were related to PV (all P < 0.01). HRR and HRV indices characterize distinct independent aspects of cardiac parasympathetic function, with HRV indices being more sensitive to changes in plasma volume than HRR.

Supramaximal Training and Postexercise Parasympathetic Reactivation in Adolescents

Repeated supramaximal exercise training is an efficient means of improving both aerobic and anaerobic energy system capacities. However, the influence of different levels of supramaximal training on parasympathetic function is unknown. To compare the effects of repeated-sprint (RS) versus high-intensity intermittent training (HIT) on performance and postexercise parasympathetic reactivation in trained adolescents. Fifteen male adolescents (15.6 +/- 0.8 yr) were divided into two groups that performed 9 wk of either RS (repeated all-out 6-s shuttle sprints; 14-20 s of recovery; N = 8) or HIT (15- to 20-s runs at 95% of the speed reached at the end of the 30-15 intermittent fitness test (V(IFT)); 15-20 s of recovery; N = 7). Groups performed intervals twice per week and maintained similar external training programs. Before and after training, performance was assessed by the V(IFT), countermovement jump (CMJ), 10-m sprint time (10 m), mean RS ability time (RSAmean), and heart rate (HRsub) level during a 6-min submaximal (60% V(IFT)) exercise test, where parasympathetic reactivation was assessed during the recovery phase (i.e., HR recovery time constant (HRRtau) and HR variability (HRV)). Parasympathetic function, V(IFT), and RSAmean were improved with HIT but not RS training. In contrast, changes in CMJ and HRsub were similar in both groups. A significant relationship was shown between the decrease in HRRtau and RSAmean (r = 0.62, P < 0.05; N = 15). HIT was more effective than RS training at improving postexercise parasympathetic function and physical performance. In addition, HRRtau, which was more sensitive to training than HRV indices, seems to be a useful performance-related measurement.