Low-tube-voltage whole-body CT angiography with extremely low iodine dose: a comparison between hybrid-iterative reconstruction and deep-learning image-reconstruction algorithms.

AIM: To evaluate arterial enhancement, its depiction, and image quality in low-tube potential whole-body computed tomography (CT) angiography (CTA) with extremely low iodine dose and compare the results with those obtained by hybrid-iterative reconstruction (IR) and deep-learning image-reconstruction (DLIR) methods. MATERIALS AND METHODS: This prospective study included 34 consecutive participants (27 men; mean age, 74.2 years) who underwent whole-body CTA at 80 kVp for evaluating aortic diseases between January and July 2020. Contrast material (240 mg iodine/ml) with simultaneous administration of its quarter volume of saline, which corresponded to 192 mg iodine/ml, was administered. CT raw data were reconstructed using adaptive statistical IR-Veo of 40% (hybrid-IR), DLIR with medium- (DLIR-M), and high-strength level (DLIR-H). A radiologist measured CT attenuation of the arteries and background noise, and the signal-to-noise ratio (SNR) was then calculated. Two reviewers qualitatively evaluated the arterial depictions and diagnostic acceptability on axial, multiplanar-reformatted (MPR), and volume-rendered (VR) images. RESULTS: Mean contrast material volume and iodine weight administered were 64.1 ml and 15.4 g, respectively. The SNRs of the arteries were significantly higher in the following order of the DLIR-H, DLIR-M, and hybrid-IR (p<0.001). Depictions of six arteries on axial, three arteries on MPR, and four arteries on VR images were significantly superior in the DLIR-M or hybrid-IR than in the DLIR-H (p≤0.009 for each). Diagnostic acceptability was significantly better in the DLIR-M and DLIR-H than in the hybrid-IR (p<0.001-0.005). CONCLUSION: DLIR-M showed well-balanced arterial depictions and image quality compared with the hybrid-IR and DLIR-H.

High-Order Harmonic Generation and Its Unconventional Scaling Law in the Mott-Insulating Ca_{2}RuO_{4}.

Competition and cooperation among orders is at the heart of many-body physics in strongly correlated materials and leads to their rich physical properties. It is crucial to investigate what impact many-body physics has on extreme nonlinear optical phenomena, with the possibility of controlling material properties by light. However, the effect of competing orders and electron-electron correlations on highly nonlinear optical phenomena has not yet been experimentally clarified. Here, we investigated high-order harmonic generation from the Mott-insulating phase of Ca_{2}RuO_{4}. Changing the gap energy in Ca_{2}RuO_{4} as a function of temperature, we observed a strong enhancement of high order harmonic generation at 50 K, increasing up to several hundred times compared to room temperature. We discovered that this enhancement can be well reproduced by an empirical scaling law that depends only on the material gap energy and photon emission energy. Such a scaling law can hardly be explained by the electronic structure change in the single particle model and has not been predicted by previous theoretical studies on HHG in the simple Mott-Hubbard model. Our results suggest that the highly nonlinear optical response of strongly correlated materials is influenced by competition among the multiple degrees of freedom and electron-electron correlations.

Deep-learning image-reconstruction algorithm for dual-energy CT angiography with reduced iodine dose: preliminary results.

AIM: To evaluate the computed tomography (CT) attenuation values, background noise, arterial depiction, and image quality in whole-body dual-energy CT angiography (DECTA) at 40 keV with a reduced iodine dose using deep-learning image reconstruction (DLIR) and compare them with hybrid iterative reconstruction (IR). MATERIAL AND METHODS: Whole-body DECTA with a reduced iodine dose (200 mg iodine/kg) was performed in 22 patients, and DECTA data at 1.25-mm section thickness with 50% overlap were reconstructed at 40 keV using 40% adaptive statistical iterative reconstruction with Veo (hybrid-IR group), and DLIR at medium and high levels (DLIR-M and DLIR-H groups). The CT attenuation values of the thoracic and abdominal aortas and iliac artery and background noise were measured. Arterial depiction and image quality on axial, multiplanar reformatted (MPR), and volume-rendered (VR) images were assessed by two readers. Quantitative and qualitative parameters were compared between the hybrid-IR, DLIR-M, and DLIR-H groups. RESULTS: The vascular CT attenuation values were almost comparable between the three groups (p=0.013-0.97), but the background noise was significantly lower in the DLIR-H group than in the hybrid-IR and DLIR-M groups (p<0.001). The arterial depictions on axial and MPR images and in almost all arteries on VR images were comparable (p=0.14-1). The image quality of axial, MPR, and VR images was significantly better in the DLIR-H group (p<0.001-0.015). CONCLUSION: DLIR significantly reduced background noise and improved image quality in DECTA at 40 keV compared with hybrid-IR, while maintaining the arterial depiction in almost all arteries.

Deep androgen receptor suppression in prostate cancer exploits sexually dimorphic renal expression for systemic glucocorticoid exposure.

BACKGROUND: Enzalutamide and apalutamide are potent next-generation androgen receptor (AR) antagonists used in metastatic and non-metastatic prostate cancer. Metabolic, hormonal and immunologic effects of deep AR suppression are unknown. We hypothesized that enzalutamide and apalutamide suppress 11ß-hydroxysteroid dehydrogenase-2 (11ß-HSD2), which normally converts cortisol to cortisone, leading to elevated cortisol concentrations, increased ratio of active to inactive glucocorticoids and possibly suboptimal response to immunotherapy. On-treatment glucocorticoid changes might serve as an indicator of active glucocorticoid exposure and resultant adverse consequences. PATIENTS AND METHODS: Human kidney tissues were stained for AR and 11ß-HSD2 expression. Patients in three trials [neoadjuvant apalutamide plus leuprolide, enzalutamide ± PROSTVAC (recombinant poxvirus prostate-specific antigen vaccine) for metastatic castration-resistant prostate cancer (CRPC) and enzalutamide ± PROSTVAC for non-metastatic castration-sensitive prostate cancer] were analyzed for cortisol and its metabolites using liquid chromatography-mass spectrometry (LC-MS/MS). Progression-free survival was determined in the metastatic CRPC study of enzalutamide ± PROSTVAC for those with glucocorticoid changes above and below the median. RESULTS: Concurrent AR and 11ß-HSD2 expression occurs only in the kidneys of men. A statistically significant rise in cortisol concentration, cortisol/cortisone ratio and tetrahydrocortisol/tetrahydrocortisone ratio with AR antagonist treatment occurred uniformly across all three trials. In the trial of enzalutamide ± PROSTVAC for metastatic CRPC, high cortisol/cortisone ratio in the enzalutamide arm was associated with significantly improved progression-free survival. However, in the enzalutamide + PROSTVAC arm, the opposite trend was observed. CONCLUSION: Enzalutamide and apalutamide treatment toggles renal 11ß-HSD2 and significantly increases indicators of and exposure to biologically active glucocorticoids, which is associated with clinical outcomes.

DS02R1: Improvements to Atomic Bomb Survivors' Input Data and Implementation of Dosimetry System 2002 (DS02) and Resulting Changes in Estimated Doses.

Individual dose estimates calculated by Dosimetry System 2002 (DS02) for the Life Span Study (LSS) of atomic bomb survivors are based on input data that specify location and shielding at the time of the bombing (ATB). A multi-year effort to improve information on survivors' locations ATB has recently been completed, along with comprehensive improvements in their terrain shielding input data and several improvements to computational algorithms used in combination with DS02 at RERF. Improvements began with a thorough review and prioritization of original questionnaire data on location and shielding that were taken from survivors or their proxies in the period 1949-1963. Related source documents varied in level of detail, from relatively simple lists to carefully-constructed technical drawings of structural and other shielding and surrounding neighborhoods. Systematic errors were reduced in this work by restoring the original precision of map coordinates that had been truncated due to limitations in early data processing equipment and by correcting distortions in the old (WWII-era) maps originally used to specify survivors' positions, among other improvements. Distortion errors were corrected by aligning the old maps and neighborhood drawings to orthophotographic mosaics of the cities that were newly constructed from pre-bombing aerial photographs. Random errors that were reduced included simple transcription errors and mistakes in identifying survivors' locations on the old maps. Terrain shielding input data that had been originally estimated for limited groups of survivors using older methods and data sources were completely re-estimated for all survivors using new digital terrain elevation data. Improvements to algorithms included a fix to an error in the DS02 code for coupling house and terrain shielding, a correction for elevation at the survivor's location in calculating angles to the horizon used for terrain shielding input, an improved method for truncating high dose estimates to 4 Gy to reduce the effect of dose error, and improved methods for calculating averaged shielding transmission factors that are used to calculate doses for survivors without detailed shielding input data. Input data changes are summarized and described here in some detail, along with the resulting changes in dose estimates and a simple description of changes in risk estimates for solid cancer mortality. This and future RERF publications will refer to the new dose estimates described herein as "DS02R1 doses."

Jump Squat is More Related to Sprinting and Jumping Abilities than Olympic Push Press.

The aim of this study was to test the relationships between jump squat (JS) and Olympic push press (OPP) power outputs and performance in sprint, squat jump (SJ), countermovement jump (CMJ) and change of direction (COD) speed tests in elite soccer players. 27 athletes performed a maximum power load test to determine their bar mean propulsive power (MPP) and bar mean propulsive velocity (MPV) in the JS and OPP exercises. Magnitude-based inference was used to compare the exercises. The MPV was almost certainly higher in the OPP than in the JS. The MPP relative to body mass (MPP REL) was possibly higher in the OPP. Only the JS MPP REL presented very large correlations with linear speed (r>0.7, for speed in 5, 10, 20 and 30 m) and vertical jumping abilities (r>0.8, for SJ and CMJ), and moderate correlation with COD speed (r=0.45). Although significant (except for COD), the associations between OPP outcomes and field-based measurements (speed, SJ and CMJ) were all moderate, ranging from 0.40 to 0.48. In a group composed of elite soccer players, the JS exercise is more associated with jumping and sprinting abilities than the OPP. Longitudinal studies are needed to confirm if these strong relationships imply superior training effects in favor of the JS exercise.

Effects of detraining on neuromuscular performance in a selected group of elite women pole-vaulters: a case study.

AIM: to determine the effects of 28 days of inactivity on neuromuscular performance of elite women pole-vaulters. METHODS: Four athletes undertook measurements of rate of force development (RFD), unloaded and loaded vertical jump tests, drop jumps and a 45 m sprint test before and after a transition period of planned inactivity. RESULTS: The RFD and the ability to accelerate over very short distances (5 m) while sprinting improved after training cessation. Acceleration over longer distances (5-45 m) was impaired, while unloaded and loaded vertical jump tests suffered trivial to small changes. CONCLUSIONS: Therefore, we conclude that detraining periods of approximately one month or even longer may be implemented in elite pole-vaulters without significantly impairing performance. In addition, given that some neuromechanical capacities are enhanced after training reduction, our results can help coaches to implement tapering strategies in order to induce neuromuscular improvements and/or to achieve peak performance.

Traditional Periodization versus Optimum Training Load Applied to Soccer Players: Effects on Neuromuscular Abilities.

It is unknown whether traditional periodization of strength-power training involving accumulation, transformation and realization blocks is superior to other simpler and more practical training schemes. The purpose of this study was thus to investigate changes in strength/power/speed characteristics of elite soccer players in response to either classic strength-power periodization (TSP) or optimum power load (OPL). 23 professional soccer players were randomly assigned to TSP or OPL for 6 weeks in-season regular training (3 times per week). TSP involved half squats or jump squats, depending on the respective training block, while OPL involved only jump squats at the optimum power load. Results revealed that both groups presented similar significant (P<0.05) improvements in squat one repetition maximum, squat and countermovement jump heights and change of direction speed. In addition, although both groups reported significant increases in sprinting speed (P<0.05); delta change scores demonstrated a superior effect of OPL to improve 10- and 20-m speed. Similarly, OPL presented greater delta change in mean propulsive power in the jump squat. Therefore, training continuously at the optimum power zone resulted in superior performance improvements compared to training under classic strength-power periodization.

Effects of far infrared rays emitting clothing on recovery after an intense plyometric exercise bout applied to elite soccer players: a randomized double-blind placebo-controlled trial.

The aim was to investigate the effects of far infrared (FIR) ray emitting clothes on indirect markers of exercise-induced muscle damage and physical performance recovery after a plyometric bout applied to soccer players. Twenty-one male players (18.9±0.6 years; 70.8±5.01 kg; 178.3±0.06 cm) performed 100 drop-jumps. Six hours after the bout, athletes put on FIR clothes (FIR) (density of 225 g·m(-2), 88% far infrared rays emitting polyamide 66 Emana yarn (PA66) fibre, 12% Spandex, emissivity of 0.88 and power emitted of 341 W/m2µm at 37°C in the 5-20 µm wavelength range, patent WO 2009/077834 A2) (N = 10) or placebo clothes (PLA) (N = 11). Mid-thigh circumferences, creatine kinase (CK), and delayed-onset muscle soreness (DOMS) were assessed before, immediately after and 24, 48, and 72 h after the bout. Squat (SJ) and countermovement jump (CMJ) heights were measured before and at 24, 48, and 72 h after, while 1RM leg press (maximum strength) was measured before and at 72 h after the plyometrics. No differences between groups were found in mid-thigh circumferences, SJ, CMJ or 1RM. CK increased significantly 24 h after the plyometrics in comparison to before (p < 0.05) in both groups. PLA showed significant DOMS increases at 24, 48, and 72 h, while FIR showed significant increases at 24 and 48 h (p < 0.05). DOMS effect sizes were greater in FIR (moderate at 48 h, ES = 0.737 and large at 72 h, ES = 0.844), suggesting that FIR clothes may reduce perceived DOMS after an intense plyometric session performed by soccer players.

Jump Training in Youth Soccer Players: Effects of Haltere Type Handheld Loading.

The aim of this study was to compare the effects of a jump training program, with or without haltere type handheld loading, on maximal intensity exercise performance. Youth soccer players (12.1±2.2 y) were assigned to either a jump training group (JG, n=21), a jump training group plus haltere type handheld loading (LJG, n=21), or a control group following only soccer training (CG, n=21). Athletes were evaluated for maximal-intensity performance measures before and after 6 weeks of training, during an in-season training period. The CG achieved a significant change in maximal kicking velocity only (ES=0.11-0.20). Both jump training groups improved in right leg (ES=0.28-0.45) and left leg horizontal countermovement jump with arms (ES=0.32-0.47), horizontal countermovement jump with arms (ES=0.28-0.37), vertical countermovement jump with arms (ES=0.26), 20-cm drop jump reactive strength index (ES=0.20-0.37), and maximal kicking velocity (ES=0.27-0.34). Nevertheless, compared to the CG, only the LJG exhibited greater improvements in all performance tests. Therefore, haltere type handheld loading further enhances performance adaptations during jump training in youth soccer players.

Effects of fertility education on knowledge, desires and anxiety among the reproductive-aged population: findings from a randomized controlled trial.

STUDY QUESTION: What are the effects of fertility education on knowledge, childbearing desires and anxiety? SUMMARY ANSWER: Providing fertility information contributed to greater knowledge, but increased anxiety. WHAT IS KNOWN ALREADY: Past studies have found that exposure to educational material improved fertility awareness and changed desires toward childbearing and its timing. Existing educational websites with evidence-based medical information provided in a non-judgmental manner have received favorable responses from reproductive-aged men and women. STUDY DESIGN, SIZE, DURATION: This three-armed (one intervention and two control groups), randomized controlled trial was conducted using online social research panels (SRPs) in Japan in January 2015. PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 1455 participants (726 men and 729 women) between 20 and 39 years of age who hoped to have (more) children in the future were block-randomized and exposed to one of three information brochures: fertility education (intervention group), intake of folic acid during pregnancy (control group 1) or governmental financial support for pregnancy and childbirth (control group 2). Fertility knowledge was measured with the Japanese version of the Cardiff Fertility Knowledge Scale (CFKS-J). Knowledge, child-number and child-timing desires, subjective anxiety (i.e. whether participants felt anxiety [primary outcome]), and scores on the State-Trait Anxiety Inventory were assessed immediately after exposure. Non-inferiority comparisons were performed on subjective anxiety with non-inferiority declared if the upper limit of the two-sided 95% confidence interval (CI) for risk difference did not exceed a margin of 0.15. This test for non-inferiority was only performed for subjective anxiety; all the other variables were tests of superiority. MAIN RESULTS AND THE ROLE OF CHANCE: Posttest scores on the CFKS-J (mean, SD) were higher in the intervention group than that of the control groups: intervention versus Control 1 and versus Control 2: 52.8 (28.8) versus 40.9 (26.2) (P< 0.001) versus 45.1 (27.1) (P = 0.003) among men and 64.6 (26.0) versus 50.8 (26.9) (P< 0.001) versus 53.0 (26.4) (P< 0.001) among women.The percentage of participants who felt subjective anxiety after exposure to the intervention brochure was significantly higher than that of the control groups: intervention versus Control 1 and versus Control 2: 32.6 versus 17.8% (risk difference [RD] = 0.149, 95% CI: 0.073-0.225) versus 14.5% (RD = 0.182, 95% CI: 0.108-0.256) among men, and 50.2 versus 26.3% (RD = 0.239, 95% CI: 0.155-0.322) versus 14.0% (RD = 0.362, 95% CI: 0.286-0.439) among women. Non-inferiority of the intervention was inconclusive (i.e. the CI included 0.15) among men whereas inferiority was declared among women. The incidence of anxiety was higher in the intervention group than that of the control groups especially among men aged 30 and older and among women aged 25 and older. No difference existed in childbearing desires between groups after exposure. LIMITATIONS, REASONS FOR CAUTION: The possibility of selection bias associated with the use of SRPs (higher socioeconomic status and education) and volunteer bias toward those more interested in fertility may limit the generalizability of these findings. WIDER IMPLICATIONS OF THE FINDINGS: In addition to education targeting a younger generation, psychological approaches are needed to alleviate possible anxiety caused by fertility information. STUDY FUNDING/COMPETING INTERESTS: This study was funded by National Center for Child Health and Development, Seiiku Medical Study Grant (24-6), the Daiwa Foundation Small Grants and Grant-in-Aid for JSPS Fellows (26-1591). No competing interest declared. TRIAL REGISTRATION NUMBER: UMIN Clinical Trials Registry. Trial registration number, 000016168. TRIAL REGISTRATION DATE: 13 January 2015. DATE OF FIRST PATIENT'S ENROLMENT: 15 January 2015.

Initial Weekly HRV Response is Related to the Prospective Change in VO2max in Female Soccer Players.

The aim of this study was to determine whether the early response in weekly measures of HRV, when derived from a smartphone application, were related to the eventual change in VO2max following an off-season training program in female soccer athletes. 9 female collegiate soccer players participated in an 11-week off-season conditioning program. In the week immediately before and after the training program, each participant performed a test on a treadmill to determine maximal oxygen consumption (VO2max). Daily measures of the log-transformed root mean square of successive R-R intervals (lnRMSSD) were performed by the participants throughout week 1 and week 3 of the conditioning program. The mean and coefficient of variation (CV) lnRMSSD values of week 1 showed small (r=- 0.13, p=0.74) and moderate (r=0.57, p=0.11), respectively, non-significant correlations to the change in VO2max at the end of the conditioning program (∆VO2max). Significant and near-perfect correlation was found between the change in the weekly mean lnRMSSD values from weeks 1 and 3 (∆lnRMSSDM) and ∆VO2max (r=0.90, p=0.002). The current results have identified that the initial change in weekly mean lnRMSSD from weeks 1 to 3 of a conditioning protocol was strongly associated with the eventual adaptation of VO2max.

A Correlational Analysis of Tethered Swimming, Swim Sprint Performance and Dry-land Power Assessments.

Swimmers are often tested on both dry-land and in swimming exercises. The aim of this study was to test the relationships between dry-land, tethered force-time curve parameters and swimming performances in distances up to 200 m. 10 young male high-level swimmers were assessed using the maximal isometric bench-press and quarter-squat, mean propulsive power in jump-squat, squat and countermovement jumps (dry-land assessments), peak force, average force, rate of force development (RFD) and impulse (tethered swimming) and swimming times. Pearson product-moment correlations were calculated among the variables. Peak force and average force were very largely correlated with the 50- and 100-m swimming performances (r=- 0.82 and -0.74, respectively). Average force was very-largely/largely correlated with the 50- and 100-m performances (r=- 0.85 and -0.67, respectively). RFD and impulse were very-largely correlated with the 50-m time (r=- 0.72 and -0.76, respectively). Tethered swimming parameters were largely correlated (r=0.65 to 0.72) with mean propulsive power in jump-squat, squat-jump and countermovement jumps. Finally, mean propulsive power in jump-squat was largely correlated (r=- 0.70) with 50-m performance. Due to the significant correlations between dry-land assessments and tethered/actual swimming, coaches are encouraged to implement strategies able to increase leg power in sprint swimmers.

To what extent do human-altered landscapes retain population connectivity? Historical changes in gene flow of wetland fish Pungitius pungitius.

Understanding how human-altered landscapes affect population connectivity is valuable for conservation planning. Natural connectivity among wetlands, which is maintained by floods, is disappearing owing to farmland expansion. Using genetic data, we assessed historical changes in the population connectivity of the ninespine stickleback within a human-altered wetland system. We predicted that: (i) the contemporary gene flow maintained by the artificial watercourse network may be restricted to a smaller spatial scale compared with the gene flow preceding alteration, and (ii) the contemporary gene flow is dominated by the downstream direction owing to the construction of low-head barriers. We evaluated the potential source population in both timescales. Seventeen studied populations were grouped into four genetically different clusters, and we estimated the migration rates among these clusters. Contemporary migration was restricted to between neighbouring clusters, although a directional change was not detected. Furthermore, we consistently found the same potential source cluster, from past to present, characterized by large amounts of remnant habitats connected by artificial watercourses. These findings highlight that: (i) artificial connectivity can sustain the short-distance connectivity of the ninespine stickleback, which contributes to maintaining the potential source populations; however, (ii) population connectivity throughout the landscape has been prevented by agricultural developments.

Reliability of the Heart Rate Variability Threshold using Visual Inspection and Dmax Methods.

The purpose of this study was to compare heart rate variability threshold (HRVT) in 6 incremental tests and test its reproducibility using visual inspection and Dmax methods for root mean square of successive differences between the adjacent normal R-R intervals (RMSSD), standard deviation of the normal RR interval (SDNN) and standard deviation of instantaneous beat-to-beat variability (SD1). 12 adult males performed an incremental test to volitional fatigue on a cycle simulator during 6 visits to the laboratory. The initial test load was 25 W, and the intensity was increased by 25 W every 3 min until volitional fatigue set in. The HRV during the incremental test was analyzed using the RMSSD, SDNN and SD1 indices and the determination of HRVT was performed using 2 methods: visual inspection and Dmax. The results demonstrated that the SD1 and RMSSD indices, determined by the visual inspection method, presented the highest reproducibility of HRVT when compared with the other indices and methods. We concluded that the best method for determining HRVT was the technique using the point of stabilization by visual inspection in the SD1 and RMSSD indices during the incremental test, due to its high reproducibility, lower coefficient of variation and increment size.

Incorporation of apical lymph node status into the seventh edition of the TNM classification improves prediction of prognosis in stage III colonic cancer.

BACKGROUND: The node classification outlined in the seventh edition of the TNM classification is based solely on the number of metastasized lymph nodes. This study examined the prognostic value of apical lymph node (ALN) metastasis and the additional value of incorporating ALN status into a risk model based on the seventh edition. METHODS: This was a cohort study of patients with stage III colonic cancer who underwent tumour resection with dissection of regional (including apical) lymph nodes at 71 hospitals across Japan between 2000 and 2002. The main exposure was pathologically confirmed ALN metastasis, and the primary endpoint was cancer-specific death. RESULTS: ALN metastasis was present in 113 (8·3 per cent) of 1355 patients. During 5356 patient-years of follow-up (median 5·0 years), 221 instances (16·3 per cent) of cancer-specific death were observed. After adjustment for tumour and node classification (as described in the seventh edition of the TNM classification) and other prognostic factors, ALN metastasis was found to be independently associated with cancer-specific death (hazard ratio 2·29, 95 per cent confidence interval (c.i.) 1·49 to 3·52). Incorporation of ALN metastasis into the prognostic model based on the seventh edition of the TNM classification significantly improved discriminative performance for cancer-specific death (difference in concordance index 0·0146, 95 per cent c.i. 0·0030 to 0·0262) and risk reclassification for cancer-specific death at 5 years (category-free net reclassification improvement 19·4 (95 per cent c.i. 5·0 to 33·4) per cent). CONCLUSION: Assessment of ALN metastasis provided independent prognostic information beyond that achievable with the seventh edition of the TNM classification in patients with stage III colonic cancer.

Reliability of heart rate measures during walking before and after running maximal efforts.

Previous studies on HR recovery (HRR) measures have utilized the supine and the seated postures. However, the most common recovery mode in sport and clinical settings after running exercise is active walking. The aim of the current study was to examine the reliability of HR measures during walking (4 km · h(-1)) before and following a maximal test. Twelve endurance athletes performed an incremental running test on 2 days separated by 48 h. Absolute (coefficient of variation, CV, %) and relative [Intraclass correlation coefficient, (ICC)] reliability of time domain and non-linear measures of HR variability (HRV) from 3 min recordings, and HRR parameters over 5 min were assessed. Moderate to very high reliability was identified for most HRV indices with short-term components of time domain and non-linear HRV measures demonstrating the greatest reliability before (CV: 12-22%; ICC: 0.73-0.92) and after exercise (CV: 14-32%; ICC: 0.78-0.91). Most HRR indices and parameters of HRR kinetics demonstrated high to very high reliability with HR values at a given point and the asymptotic value of HR being the most reliable (CV: 2.5-10.6%; ICC: 0.81-0.97). These findings demonstrate these measures as reliable tools for the assessment of autonomic control of HR during walking before and after maximal efforts.

Cardiac autonomic control in high level Brazilian power and endurance track-and-field athletes.

The autonomic nervous system (ANS) has an important role in physical performance. However, the cardiac ANS activity in high-level track and field athletes has been poorly explored. Thus, we tested the hypothesis that endurance and power athletes would present a markedly different cardiac autonomic control at rest. We analyzed the cardiac ANS by means of time and frequency domains heart rate variability (HRV) analyses and by symbolic analysis. Endurance athletes showed higher pulse interval than power athletes (1,265±126 vs. 1,031±98 ms respectively; p<0.05). No differences were found in time and frequency domains between the groups. However, the LF%, HF% and LF/HF ratio presented high effect sizes (1.46, 1.46 and 1.30, respectively). The symbolic analysis revealed that endurance athletes had higher 2V parasympathetic modulation (36±6.5) than power athletes (24±9.3; p<0.05). A reduced 0V sympathetic modulation was observed in endurance athletes (21±9.9) compared to power athletes (33±11; p<0.05 and ES=1.30). Our results suggest greater parasympathetic modulation and less sympathetic modulation in endurance athletes compared to power athletes. Additionally, the type of HRV analysis needs to be chosen with well-defined criteria and caution because their use in assessing cardiac autonomic modulation can interfere with the interpretation of results. In practical terms, symbolic analysis appears to better discriminate between cardiac autonomic activities of athletes with different training backgrounds than frequency domain analysis.