Post-exercise Heart Rate Variability Research Articles

Reliability of recovery heart rate variability measurements as part of the Lamberts Submaximal Cycle Test and the relationship with training status in trained to elite cyclists.

To determine if post-exercise heart rate variability, in the form of logged transformed root mean square of successive differences of the R-R intervals (LnRMSSD) can be measured reliably during the recovery from a submaximal cycle test and what the relationship of LnRMSSD is with training status of the cyclists. Fourteen male cyclists participated in the reliability part for the study, which included performing six Lamberts Submaximal Cycle Test (LSCT), during which recovery LnRMSSD was measured over 30 s (LnRMSSD30 s), 60 s LnRMSSD60 s)and 90 s LnRMSSD90 s). In addition, fifty male and twenty female cyclists completed a peak power output (PPO) test (including VO2peak) and 40km time trial (40km TT) before which they performed the LSCT as a standardized warm-up. Relationships between the LnRMSSD and PPO, VO2peak and 40km TT time were studied. Due to the design of the LSCT, submaximal heart and breathing rate were similar at the end of stage 3 of the LSCT, as well as during the recovery periods. The highest reliability was found in LnRMSSD60 s (ICC: 0.97) with a typical error of the measurement (TEM: 5.8%). In line with this the strongest correlations were found between LnRMSSD60 s and PPO (r = 0.93[male]; 0.85[female]), VO2peak (r = 0.71[male]; 0.63[female];) and 40km TT (r = -0.83[male]; -0.63[female]). LnRMSSD60 s can be measured reliably after the LSCT and can predict PPO, VO2peak and 40km TT performance well in trained-to-elite cyclists. These findings suggest that recovery LnRMSSD can potentially play an important role in monitoring and fine-tuning training prescriptions in trained-to-elite cyclists.

Post-exercise heart rate variability recovery after 800-m endurance run load among Cameroonian adolescent's males

The 800-m (m) run is part of Physical Education classes in Cameroon, after which arrhythmias may occur during recovery. Hence, this study aimed at determining relationship between 800-m run loads on cardiac autonomic recovery among school adolescents.Forty-two male adolescents (aged [17 ​± ​1] years) performed 800-m. Post-exercise heart rate variability (HRV) was recorded during 5-min (min) (HRV5-min) and 15-min (HRV15-min) in time: Standard deviation of normal to normal (SDNN); Root mean square of successive differences (RMSSD) and frequency domain (LH: Low frequency, HF: High frequency, TP: Total power). Rating of Perceived Exertion (RPE) and blood lactate concentration (BLa) were measured after exercise. In HRV5-min, RPE was associated with SDNN (r ​= ​−0.44, p ​< ​0.01) and RMSSD (r ​= ​−0.38, p ​< ​0.05). BLa was correlated with SDNN (r ​= ​−0.38, p ​< ​0.05) and RMSSD (r ​= ​−0.56, p ​< ​0.001) in the time-domain, LF (r ​= ​−0.64, p ​< ​0.001), HF (r ​= ​−0.58, p ​< ​0.001) and TP (r ​= ​−0.61, p ​< ​0.001) in frequency-domain. Moreover, RPE was correlated with LF (r ​= ​−0.44, p ​< ​0.01), TP (r ​= ​−0.49, p ​< ​0.01) while exercise duration with HF (r ​= ​−0.38, p ​< ​0.05). In HRV15-min, BLa was correlated with RMSSD (r ​= ​−0.53, p ​< ​0.001) and SDNN (r ​= ​−0.68, p ​< ​0.001). RPE was negatively correlated SDNN (r ​= ​−0.53, p ​< ​0.01) and RMSSD (r ​= ​−0.44, p ​< ​0.01). BLa was associated with HF (r ​= ​−0.55, p ​< ​0.001), TP (r ​= ​−0.50, p ​< ​0.01) and RPE with LF (r ​= ​−0.51, p ​< ​0.01), HF (r ​= ​−0.50, p ​< ​0.01), TP (r ​= ​−0.49, p ​< ​0.01). In addition, exercise duration was negatively linked to HF (r ​= ​−0.36, p ​< ​0.05). This study outlined that in untrained adolescents an increase of 800-m loads is associated with a slow vagal indexes of HRV during the recovery.

A post-exercise infrared sauna session improves recovery of neuromuscular performance and muscle soreness after resistance exercise training.

The aim of this study was to investigate effects of a single infrared sauna (IRS) session on post-exercise recovery of neuromuscular performance, autonomic nervous system function, subjective sleep quality, and muscle soreness. Male basketball players (n = 16) performed two trials consisting of a complex resistance exercise protocol (maximal strength with plyometrics), followed by either 20 min passive recovery (PAS) or IRS (temperature 43 ± 5°C), in a randomized crossover design, with trials separated by one week. Recovery of neuromuscular performance was assessed using 20 m maximal sprint, maximal countermovement-jump (CMJ), and isometric leg press tests, performed 14 hours after exercise. Heart rate (HR), heart rate variability (HRV), sleep diary, muscle soreness, and indirect muscle damage markers were measured pre and post exercise. The decrease in CMJ performance from pre- to post-exercise was attenuated after IRS compared to PAS (p < 0.01). The IRS session resulted in higher HR and lower root mean square of successive differences between normal heartbeats (RMSSD), and high and low frequency power, compared to PAS (p < 0.002). Post-exercise night-time HR and HRV did not differ following IRS vs. PAS. Muscle soreness was less severe, and perceived recovery was higher after IRS compared to PAS (p < 0.01). Post-exercise IRS attenuated the drop in explosive performance and decreased subjective muscle soreness after resistance training, which may enhance mood, readiness, and physical performance of an athlete. A single IRS session had no detrimental effects on recovery of the autonomic nervous system.

Heart rate variability, task load and perceived exertion associated with a long-distance military ski exercise: A pilot study

Objectives: Skiing is practiced by the security forces posted at mountain areas for patrolling, securing borders, taking up rescue missions and sometimes as recreational activities. A study was planned to assess physiological and mental stress of a military ski activity through the measurement of heart rate (HR) variability, task load and perceived exertion. Materials and Methods: Eleven healthy Indian soldiers, trained with skiing techniques, participated in a 15 km skiing with 22 kg equipment at a predetermined snowy mountainous track. Pre- and post-exercise HR and HR variability (HRV) were recorded (bio-harness, Zephyr, USA) and questionnaires, namely NASA task load index (NASA-TLX) and Borg’s rating of perceived exertion (RPE) scale, were filled after exercise. Time and frequency domain parameters such as HR, variations between successive RR intervals (RMSSD), standard deviation of RR (SDNN) and percentage value of NN50 (pNN50), low- and high-frequency bands (LF and HF %) and LF/HF ratio were derived using Kubios software. Student’s t (paired) test was applied to compare pre- and post-exercise HRV parameters and Pearson’s correlation was applied to observe interdependencies between HRV and subjective scores. Results: The findings depicted increase in post-exercise HR and decrease in overall HRV (both significant). Besides this, there was an increase in LF (significant) and LF/HF ratio (insignificant). Such response shows sympathetic dominance over parasympathetic domain of autonomic nervous system. The physical and mental stress experienced during the exercise was also expressed through high physical demand (79 out of 100) and high overall task load (total score – 77 out of 100) of the NASA-TLX and a moderately heavy RPE score (14 out of 20). Conclusion: The pre- and post-exercise differences in physiological variables ensured the presence of physical stress along with dominance of sympathetic nervous system. Overall task load was depicted with high subjective ratings. Carrying out skiing task in an environment infested with cold, wind chill, moderate hypoxia at a snowy and mountainous track possibly has induced the observed physiological and mental stress to the participants. Such findings are important to understand exact requirements of the mountain warfare events carried out by the forces.

Cardiac autonomic disturbance following resistance and sprint-interval exercises in non-obese and obese young men.

This study examined the alterations of heart rate variability (HRV) following iso-duration resistance (RES) and sprint-interval exercises (SIE) by comparing with that of non-exercise control (CON) in 14 non-obese (NOB) and 15 obese (OB) young men. Time and frequency domain measures as well as nonlinear metrics of HRV were assessed before and immediately after exercise, and during every 20min until 120min post-exercise. The variables during the first 4h of actual sleep time at night, and the period of 12-14h post-exercise were also measured. All trials were scheduled at 20:00. It was found that RES and SIE attenuated the HRV in both NOB and OB (P<0.05), and the attenuated HRV restored progressively during subsequent recovery. Although the changes in HRV indices among various time points during the recovery period and its interaction across RES, SIE, and CON were not different between NOB and OB, the restoration of the declined HRV indices to corresponding CON level in the 2 exercise trials in OB appeared to be sluggish in relative to NOB. Notwithstanding, post-exercise HRV that recorded during actual sleep at night and during 12-14h apart from exercise were unvaried among the 3 trials in both groups (P>0.05). These findings suggest that obesity is likely to be a factor hindering the removal of exercise-induced cardiac autonomic disturbance in young men. Nonetheless, the declined HRV following both the RES and SIE protocols was well restored after a resting period of ∼10h regardless of obesity. The study was registered at ISRCTN as https://doi.org/10.1186/ISRCTN88544091.

Differences in Nervous Autonomic Control in Response to a Single Session of Exercise in Bodybuilders Using Anabolic Androgenic Steroids.

Considering the role of autonomic nerve activity in blood pressure control, this study aimed to investigate the cardiac autonomic nerve responses after an aerobic exercise session in Anabolic Androgenic Steroids (AAS) users. Twenty men (AAS, n = 9; control group, n = 11) performed an aerobic exercise session (60 min, 70 to 80% of HRmax). Heart rate variability (HRV) was assessed before and during a 60-min post-exercise recovery period. RMSSD (root mean square successive difference of the RR intervals) and the LF/HF ratio (low frequency/high frequency spectra) were also evaluated. The Student's t-test for independent samples was used to compare differences between initial group characteristics. Repeated measures ANOVA was used to compare pre- and post-exercise HRV recovery (p < 0.05). AAS had a lower SDNN (standard deviation of the intervals) (40.8 ± 16.8 vs. 71.6 ± 24.7 ms; p = 0.04, d = 1.4) and a higher LF/HF (3.4 ± 2.1 vs. 1.8 ± 0.9%; p = 0.03, d = 0.9) before exercise. AAS and controls had similar RMSSD (14.0 ± 15.8 vs. 18.9 ± 12.1 ms; p = 0.20) and a LF/HF (2.8 ± 1.6 vs. 2.4 ± 1.2 ms; p = 0.41) immediately post-exercise. The between-groups comparison revealed a higher HF/LF at 30 min (4.3 ± 1.4 vs. 2.5 ± 1.3%; p = 0.008, d = 1.3) and 60 min (5.0 ± 2.2 vs. 2.3 ± 0.8%; p = 0.001, d = 1.6) for the AAS group in the recovery time. This study demonstrated impaired parasympathetic activity at rest and immediately after the exercise session as an adverse effect of AAS usage, but similar behavior regarding the restoration of sympathetic activity.

Cardiac autonomic disturbance following sprint-interval exercise in untrained young males: Does exercise volume matter?

ObjectivesThis study examined the influences of the volume of all-out sprint-interval exercise (SIE) on acute post-exercise heart rate variability (HRV) recovery. MethodsHRV recovery following a session of (i) 2 × 30-s SIE (SIE2), (ii) 4 × 30-s SIE (SIE4), and (iii) non-exercising control (CON) were compared in 15 untrained young males. Time domain [standard deviation of normal-to-normal intervals, root mean square of successive R-R differences] and frequency domain [low frequency (0.04–0.14 Hz), high frequency (0.15–0.40 Hz)] measures of HRV were assessed every 20 min for 140 min after the exercise, and every hour during the first 4 h of actual sleep time at immediate night. All trials were scheduled at 19:00. ResultsIn comparison to CON, both SIE2 and SIE4 attenuated the HRV markedly (p < 0.05), while the declined HRV restored progressively during recovery. Although the sprint repetitions of SIE4 was twice as that of SIE2, the declined HRV indices at corresponding time points during recovery were not different between the two trials (p > 0.05). Nevertheless, the post-exercise HRV restoration in SIE2 appeared to be faster than that in SIE4. Regardless, nocturnal HRV measured within 10 h following the exercise was not different among the SIE and CON trials (p > 0.05). ConclusionSuch findings suggest that the exercise volume of the SIE protocol may be a factor affecting the rate of removal of the cardiac autonomic disturbance following the exercise. In addition, rest for ∼10 h following either session of the SIE protocol appears to be appropriate for the cardiovascular system to recover.

Heart rate variability associated with acute exercise challenge in children with sickle cell anaemia.

We examined heart rate variability (HRV) during exercise testing in 20 children with sickle cell anaemia (SCA) and 12 controls. Subjects achieved lower median HRV at peak exercise [standard deviation of R-wave to R-wave intervals (SDNN), 2·3 vs 2·9ms, P=0·027; logarithmic transformation of high frequency power (lnHF), 0·9 vs 1·3 ln(ms2 ), P=0·047] and had lower post-exercise HRV across minute-by-minute analysis of recovery. After adjustment for haemoglobin, fitness and SCA status, subjects had lower HRV at the end of recovery with differences increasing as baseline HRV increased. Further investigation of HRV and exercise safety in SCA is warranted.

The Role of Cholinesterases in Post-Exercise HRV Recovery in University Volleyball Players

Some studies show interest in measuring heart rate variability (HRV) during post-exercise recovery. It is known that the parasympathetic system is relevant during this process, where one of the factors of this modulation is the interaction of acetylcholine and cholinesterases (ChE). However, the behavior of ChE and its relationship during recovery is little known; therefore, the objective of this study was to analyze the behavior of ChE and its relationship with recovery evaluated in HRV indicators in volleyball players. An exercise protocol with long-term and intermittent high-intensity phases was applied in nine volleyball players. HRV measurements were made, and blood samples were drawn to evaluate the ChE before exercise and after 24 and 48 h post-exercise. The results show a modification of the variables after exercises with respect to the baseline values (ChE: 1818.4 ± 588.75 to 2218.78 ± 1101.58; RMSSD: 42.64 ± 12.86 to 17.72 ± 12.55 (p &lt; 0.05); SS: 8.76 ± 1.93 to 21.93 ± 10.05 (p &lt; 0.01); S/PS Ratio: 0.32 ± 0.14 to 3.26 ± 3.28 (p &lt; 0.01)), as well as recovery after 24 and 48 h with respect to postexercise (ChE: 1608.81 ± 546.88 (p &lt; 0.05) and 1454.54 ± 580.45 (p &lt; 0.01); RMSSD: 43.83 ± 24.50 and 46.18 ± 33.22 (p &lt; 0.01); SS; 10.93 ± 5.16 and 11.86 ± 4.32 (p &lt; 0.01); S/PS Ratio: 0.46 ± 0.32 and 0.50 ± 0.28 (p &lt; 0.01)). ChE correlations (p &lt; 0.001) were found with moderate (SS: r = 0.465) and large (RMSSD: r = −0.654; S/PS Ratio: r = 0.666) HRV indexes. In conclusion, ChE modifications are related to changes in HRV showing a very similar behavior in the case of the study subjects.

Post-exercise Heart Rate Variability: Whole-body Cryotherapy vs. Contrast Water Therapy.

High-intensity training sessions are known to alter cardiac autonomic modulation. The purpose of this study was to compare the effects of whole-body cryotherapy, contrast water therapy and passive recovery on the time course of cardiac autonomic markers following a standardized HIT session. Eleven runners completed a high intensity session followed by one of the following recovery interventions: whole-body cryotherapy, contrast water therapy or passive recovery. Changes in cardiac autonomic modulation were assessed in supine and standing positions during an active tilt test at pre-, post-14 h and post-38 h. In supine, high-frequency power increased from pre- to post-14 h following whole-body cryotherapy (1661.1±914.5 vs. 2799.0±948.4 ms2, respectively; p=0.023) and contrast water therapy (1906.1±1327.9 vs. 4174.3±2762.9 ms2, respectively; p=0.004) whereas high frequency power decreased in response to passive recovery (p=0.009). In standing, low-frequency power increased from pre-to post-38 h (1784.3 ± 953.7 vs. 3339.8±1862.7 ms2, respectively; p=0.017) leading to an increase in total power from pre- to post-38 h (1990.8 ± 1089.4 vs. 3606.1±1992.0 ms2, respectively; p=0.017). Spectral analysis revealed that contrast water therapy appears to be a more efficient recovery strategy than whole-body cryotherapy in restoring cardiac autonomic homeostasis.

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.

Long-Term Influence of Concussion on Cardio-Autonomic Function in Adolescent Hockey Players.

Concussion may negatively influence cardiovascular function and the autonomic nervous system, defined by alteration in heart rate variability (HRV). Differences in HRV most commonly emerge during a physical challenge, such as the final steps of the return-to-sport progression. To assess the effect of concussion history on aspects of cardio-autonomic function during recovery from a bout of submaximal exercise in adolescent male hockey athletes. Case-control study. Research laboratory. Thirty-three male athletes participating in Midget-AAA hockey were divided into those with (n = 15; age = 16 ± 1 years, height = 1.78 ± 0.06 m, mass = 73.9 ± 7.4 kg, 10.5 ± 1.6 years of sport experience, 25.2 ± 18.3 months since last injury) or without (n = 18; age = 16 ± 1 years, height = 1.78 ± 0.05 m, mass = 74.8 ± 7.6 kg, 10.6 ± 1.9 years of sport experience) a concussion history. Those with a concussion history were binned on total count: 1 concussion or 2 or more concussions. All athletes underwent 5 minutes of resting HRV assessment, followed by 20 minutes of aerobic exercise at 60% to 70% of their maximal target heart rate and a 9-minute, postexercise HRV assessment. Heart rate variability measures of mean NN interval, root mean square of successive differences, and standard deviation of NN interval (SDNN). Group demographic characteristics were not different. When the control and concussed groups were compared, group and time main effects for heart rate recovery, root mean square of successive differences, and SDNN (P values < .01), and an interaction effect for SDNN (P < .05) were demonstrated. Recovery trends for each group indicated that a history of 2 or more concussions may negatively affect cardio-autonomic recovery postexercise. Our findings suggest that those with more than 1 previous concussion may be associated with a greater risk for long-term dysautonomia. Future use of HRV may provide clinicians with objective guidelines for concussion-management and safe return-to-participation protocols.

Differences in autonomic heart rate modulation during rest and after a supramaximal anaerobic test in relation to gender and the menstrual cycle in women

Background/Aim. Heart rate variability (HRV) and heart rate recovery (HRR) show differences between genders, and dissimilarities were also reported in women in various menstrual cycle (MC) phases. The aim of this research was to analyze cardiac autonomic indices during rest and in re-covery after the Wingate test between genders in the young, sedentary population and to investigate whether a MC phase in women can influence these indi-ces. Methods. Twenty-five females (20.5 ? 0.7 years) and sixteen males (20.4 ? 0.7 years) performed the Wingate anaerobic test on a cycle ergometer while their HRR and resting and recovery HRV indices were obtained. In fe-males, data were collected during three distinctive MC phases. Results. The natural logarithm of low-frequency (lnLF) HRV marker and the natural logarithm of high-frequency (lnHF) HRV marker were higher in males dur-ing rest compared to women in all MC phases, except in the late follicular phase, where no differences in lnHF be-tween genders were observed. Markedly higher lnLF and lnHF were recorded in males after the Wingate test. There were no differences in HRV between women in various MC phases during rest. Surprisingly, parasympathetic time-domain marker (the square root of the mean squared dif-ferences of successive NN intervals, RMSSD) and lnLF were both higher in the early follicular phase in compari-son to the luteal phase of MC during recovery. HRR was faster in men in comparison to women in all MC phas-es. Conclusion. Males show greater HRR and total varia-bility during rest and recovery, but it appears that resting parasympathetic activity is similar when females are in the late follicular phase of MC. Intra-female resting autonomic variability is not affected by the sex hormonal cycle. Post-exercise HRV in the early follicular phase reflects a signifi-cantly favourable autonomic profile in comparison to the luteal phase of MC.

Prevalence of vitamin D deficiency among patients visiting a tertiary care centre

Background: Heart rate variability (HRV) as a measurement of autonomic function assumes great clinical importance. It is well known that particular patterns of body fat distribution increase coronary heart disease risk both in adults and children. While frank obesity is associated with reduced HRV, indicative of poorer autonomic nervous system (ANS) function, the association between body mass index (BMI) and HRV is less clear. The dynamic autonomic responses during exercise can be measured to give actionable information for training by analysis of the ECG to determine heart rate variability. While application of HRV has been applied to predict sudden cardiac death and diabetic neuropathy in assessing disease progression. The study revealed the changes in HRV in resting condition and also after a single bout of sub maximal treadmill exercise (50% of VO2 max.) among males and females in the age group of 17-25 years at rest, and the correlations between the HRV parameters at rest and after the exercise with BMI and WHR in the subjects. An observational cross sectional study was conducted in the Physiology Department of R.G.Kar Medical College, Kolkata, India on 60 subjects (n=60) of both sexes (30 males and 30 females) in the 17-25 years age, participated in this study. Their WHR and BMI were measured and HRV was recorded during rest and immediately after exercise by digital Polyrite. Result showed that the HRV of male were more than in female in resting condition. After submaximal exercise the HRV value of males were more than their respective resting HRV values though it was not significant and, in the females, post-exercise HRV was significantly more than their respective resting HRV. This study shows that females have higher parasympathetic activity than males. There is an association between WHR and BMI and HRV in healthy female persons, which shows that there is an increase in LF/HF(low frequency and high frequency) of values among males and females after a single bout of submaximal exercise though not significant in case of males but significant in case of females.

Effects of Breakfast Omission on Resting, Exercise, and Postexercise Autonomic and Hemodynamic Profile in Men

ABSTRACT Purpose: The acute effects of fasting interventions on metabolic dynamics have been widely investigated. However, knowledge about the acute effect of overnight fasting on hemodynamic and cardiac autonomic modulation is limited, especially during and after exercise. Our objective was to investigate the effects of breakfast omission on hemodynamic and cardiac autonomic modulation during different stress conditions. Method: Twenty-one young men [age: 20.3 (20.1, 26.5 years); body mass index: 22.7 (21.4, 24.4 kg/m2)] underwent resting and postexercise blood pressure assessments and heart rate variability (HRV) analysis, using the SD1 and SD2 indices of Poincaré plots, at rest in supine and standing positions, every 10 minutes during moderate cardiorespiratory training and every 10 minutes throughout the postexercise recovery phase, for a total of 30 minutes for each phase (exercise and recovery). All measurements were performed in a randomized order after overnight fasting or 60 minutes after a breakfast containing ~20% of the total recommended daily calories. The normality hypothesis was rejected, and the Wilcoxon test was conducted to compare the interventions (p < .05). Results: No differences between interventions were observed for resting and postexercise blood pressures (p = .21 to 0.87) or for resting, exercise, and postexercise SD1 (p = .10 to 0.82) and SD2 indices (p = .14 to 0.71). Conclusions: We concluded that overnight fasting does not promote significant changes in resting and postexercise blood pressures or cardiac autonomic modulation in young men at rest (in supine and standing positions), during 30 minutes of moderate cardiorespiratory training and throughout a 30-minute postexercise recovery phase.

Resting and post-exercise heart rate variability in type 2 diabetes with and without cardiac autonomic neuropathy: Preliminary results

Cardiac Autonomic Neuropathy (CAN) is a common underdiagnosed complication of type 2 diabetes (DT2). Heart Rate Variability (HRV) at rest, in the time and frequency-domain, has been shown to effectively diagnose CAN. Post-exercise recovery period is associated with changes in parasympathetic and sympathetic control, allowing potential identification of autonomic alterations that are not evident in resting condition. To compare resting and post-exercise recovery HRV frequency variables in DT2 patients with and without CAN and control participants. Thirty-six DT2 patients and 12 control participants (CG) were included. DT2 were divided in DT2 with CAN (CAN+; n = 14) and without CAN (CAN-, n = 22) based on cardiovascular autonomic reflex tests. All subjects performed the six-minutes walking test (6MWT). HRV analysis was assessed during 5 minutes in time and frequency domain (Total Power Spectrum (TP), Low-Frequency (LF), High Frequency (HF), LF/HF ratio) at rest and post-exercise. Statistical comparisons between groups were performed by one-way and repeated measure ANOVA. CAN+ and CAN- performed lower distance to 6WMT than CG (401 ± 98; 449 ± 76; 541 ± 65 m, respectively P < 0.001) despite similar exercise intensity. At rest, TP was lower in CAN+ and CAN- than CG (105 ± 75; 407 ± 290 and 1300 ± 1197ms 2 , respectively P < 0.001) with lower value in CAN+ than CAN-. No significant differences in normalized LF and HF were noted between groups. During recovery, TP decreased in CG whereas it increased in CAN+ and did not change in CAN-. Normalized LF and LF/HF ratio increased significantly while normalized HF decreased in the three groups with no difference between groups. The different TP changes from rest to recovery between groups were not associated with different changes in LF and HF components. Further LF and HF post-exercise kinetics analysis will be necessary to explain the underlying mechanisms.

Cardiac Parasympathetic Reactivation Following Small-Sided Games, Repeated Sprints and Circuit Training in Elite Handball Players.

To compare acute parasympathetic reactivation following usual training exercises, the acute post-exercise heart rate (HR) and heart rate variability (HRV) were analysed. Fourteen elite male handball players completed three separate sessions of 16-min small-sided games (SSGs), repeated sprints (RSs) consisting of two sets of six repetitions of a 25-m sprint with a 180° change of direction (12.5 m + 12.5 m) every 25 s and 40 min of handball-specific circuit training (CT, one brief action every 40 s). The HR was recorded during the exercises; HRV was assessed 10 min before and after exercise. The exercise HR was higher for SSGs than RSs and it was higher for RSs than CT. Comparison of the baseline and acute post-exercise HRV values showed that parasympathetic indices decreased following SSG (p < 0.01 – p < 0.0001; large effect size) and RS (p < 0.05 –p < 0.01; large effect size) interventions. For CT, recovery values remained similar to the baseline (small effect size). The comparison of the acute recovery period between exercise modalities showed that the root mean square of the successive differences (RMSSD) was lower for SSGs than RSs and CT. No difference in any HRV indices was observed between RSs and CT. Time-varying of RMSSD for successive 30 s segments during the 10 min recovery period showed lower values for SSGs than CT for all tested points; the progressive increase in the beat-to-beat interval was similar for all interventions. In conclusion, SSGs caused the greatest post-exercise vagal disruption and it is likely that CT is the exercise modality that least delays over-all recovery. These results might help coaches design better training sessions by understanding athletes’ recovery status after completing their conditioning exercises.

Does firefighters’ physical fitness influence their cardiac parasympathetic reactivation? Analysis with post-exercise heart rate variability and ultra-short-term measures

Purpose. This study assessed the influence of firefighters' physical fitness on performances and parasympathetic reactivation in rescue interventions, and tested the validity of post-exercise ultra-short-term heart rate variability. Methods. Twenty-four firefighters were assigned to two groups based on their fitness and performed three simulated interventions. The mean completion time was recorded. The post-exercise root mean square of successive differences of R–R intervals (LnRMSSD) was determined from both criterion (between 5 and 10 min) and ultra-short-term (every 1-min segment from minutes 0–6) analyses. Results. Completion time was better for the highest fitness group in the three simulated interventions while post-exercise LnRMSSD was not influenced by the firefighters' fitness. Reliability between ultra-short-term and criterion analyses differed between the segments tested; minute 5–6 revealed the highest intra-class correlations (0.86–0.97). Concerning sensitivity of both analyses, the criterion analysis revealed differences between the three rescue interventions and the fitness test, but these results were not observed with ultra-short-term measures. Conclusions. Fitness was associated with firefighters’ performances but not with parasympathetic reactivation in the firefighting intervention. The ultra-short-term measures do not seem to be a suitable post-exercise LnRMSSD analysis because of the low sensitivity to reveal differences among exercise conditions.

Basal and post-exercise heart rate variability correlates with training load in endurance athletes

Objective: Heart rate variability has been proposed as a valid method to examine the individual response to training load in endurance athletes. Thanks to this tool, the relationship between basal and post-exercise Heart rate variability measurements can be analyzed during a microcycle (one week) using straight values or their coefficients of variation.&#x0D; Method: Ten amateur endurance athletes (n = 5 men, n = 5 women) were monitored during a 7-day microcycle that included three road-cycling sessions, two running sessions and two trail-running sessions. The RR series were measured for 5 minutes upon wake up and after training, in a seating position, using a chest strap.&#x0D; Results: Basal and post-exercise Heart rate variability measurements showed high correlation when weekly mean values were used, very similar to when coefficients of variation values were used. In women, the root mean square of successive differences (RMSSD) was: r= 0.73; RMSSD coefficients of variation (RMSSDcv) was: r= 0.66; natural logarithm (Ln) RMSSD: r= 0.68; LnRMSSDcv: r= 0.79; and in men it RMSSD was: r= 0.78; RMSSDcv: r= -0.62; LnRMSSD: r= 0.75; LnRMSSDcv: r= -0.73).&#x0D; Conclusion: the relationship between these two measurements could be useful to program the training loads of the following microcycle.

Effect of Protective Equipment on Firefighters' External and Internal Workloads During a Simulated Rescue Intervention.

Marcel-Millet, P, Ravier, G, and Groslambert, A. Effect of protective equipment on firefighters' external and internal workloads during a simulated rescue intervention. J Strength Cond Res 36(8): 2291-2297, 2022-Firefighter's protective equipment is one of the main factors increasing psychophysiological demand during rescue intervention. Workload quantification defines the amount of stress placed on an individual. This study aimed to test the relationships and compare different workload methods to discriminate 3 protective equipment conditions based on simulated rescue intervention. The protective equipment was (a) personal protective clothing (PPC); (b) PPC and a self-contained breathing apparatus (SCBA), including a cylinder, a full-face piece, and a breathing regulator; and (c) PPC and only the cylinder of the SCBA (SCBAc). Workload was determined using methods based on heart rate (HR), perceived exertion (sRPE), acceleration, and an indirect method based on postexercise HR variability. Differences between conditions were analyzed with repeated-measures analyses of variance. Relationships between workload methods were determined using Pearson's correlations. Statistical significance was set at p < 0.05. The HR-based and sRPE methods showed higher values in the SCBA and SCBAc conditions than the PPC condition ( p < 0.0001); only the sRPE method had a higher workload for the SCBA condition than the SCBAc condition ( p < 0.0001). Acceleration-based workloads were lower in the SCBA and SCBAc conditions than the PPC condition ( p < 0.0001). The indirect method revealed no difference between the 3 conditions. Significant relationships were observed between the HR-based and sRPE methods ( r = 0.544-0.738). Inverse significant correlations were observed between the HR-based and sRPE methods and the acceleration workload methods ( r = -0.319 to -0.762). Although HR-based and sRPE methods might quantify the workloads, the sRPE method was more sensitive to discriminate between the SCBAc and SCBA conditions.