Performance during the Wingate anaerobic test and muscle morphology in males and females

Performance indices during the Wingate 30-s anaerobic test and their relationship to muscle morphology of the vastus lateralis muscle were studied in 30 untrained male and female subjects. Absolute values for peak power (P05), total work performed (TW), power decrease (PD), and post-test blood lactate concentration were significantly greater for the male subjects. When expressed per unit of body mass or leg volume, both P05 and TW were larger for the males than the females (P less than 0.05). Significant correlations were noted for P05, TW, PD, and blood lactate and the percent of fast-twitch (FT) fibers and the percent relative area of FT fibers for the male but not the female subjects. The results from this experiment reveal a significant influence of muscle morphology on short-term anaerobic work performance for these male subjects. The absence of a similar relationship for the women subjects was likely due to the use of an inappropriately high resistance setting.     

Heart rate variability during high ambient heat exposure

INTRODUCTION: This study observed heart rate variability (HRV) measured in order to detect the changes in sympathovagal activity during high ambient (74 degrees C) temperature. HRV is a measure of heart rate (HR) fluctuations around the mean HR and has been used to indicate the balance between parasympathetic and sympathetic function of the autonomic nervous system in medicine and exercise, but not in extreme environments. METHODS: There were 10 healthy male subjects who wore Polar HR monitors (PE 5000) during a 15-min exposure (74.3 +/- 5.9 degrees C). RESULTS: HR increased significantly (p < 0.05) from 66.5 bpm pre-exposure to 106.0 bpm during exposure to the dry heat. A significant decrease in parasympathetic drive was indicated by: (1) a reduction of 89.1 +/- 31.3% in the proportion of interval differences between two normal R-R intervals that were in excess of 50 ms in length (pNN50); (2) an 83.4 +/- 7.0% decrease in the root mean square of successive R-R differences (RMSSD); and (3) an 82.7 +/- 11.4% decrease in the normalized high-frequency (HF norm) values. An increase in a sympathetic drive was indicated by a significant increase in: (1) the normalized low-frequency (LF norm) values of (84.5 +/- 19.4%); and (2) the LF:HF ratio (10.9 +/- 10.8%). DISCUSSION: The results from this study show that exposure to high ambient temperature produces a significant increase in HR through an increase in sympathetic and decrease in parasympathetic drive.     

Effects of acute salbutamol intake during a Wingate test

To investigate the impact of acute salbutamol intake on performance and selected hormonal and metabolic variables during supramaximal exercise, 13 recreational male athletes performed two 30-second Wingate tests after either placebo (PLA, lactose) or salbutamol (SAL, 4 mg) oral administration, according to a double-blind and randomized protocol. Blood samples collected at rest, end of the Wingate test, recovery (5, 10, 15 min) were tested for growth hormone (GH), insulin (INS), blood glucose (GLU), and lactate determination. We found the peak and mean power performed significantly increased after SAL vs. PLA (PPSAL: 896 +/- 46; PPPLA: 819 +/- 57 W; MPSAL: 585 +/- 27; MPPLA: 534 +/- 35 W, p < 0.05), whereas no change was observed in the fatigue index. Blood glucose and INS were significantly increased by SAL at rest, at the end of the Wingate test, and during the 5 first minutes of recovery (p < 0.05). Plasma GH was significantly decreased by SAL (p < 0.05) during the recovery whereas end-exercise and recovery blood lactate tended but were not significantly increased after SAL vs. PLA. From these data, acute salbutamol intake at therapeutical dosage did appear to improve peak power and mean power during a supramaximal exercise, but the mechanisms involved need further investigation.     

Effects of short-term salbutamol ingestion during a Wingate test

The effects of a chronic salbutamol intake (SAL, 12 mg/d during 3 weeks) on changes in body composition, metabolic indices and performance during a 30-second Wingate test were determined in 8 strength-trained male athletes (T) and 7 sedentary male (UT) subjects, according to a double-blind, randomized, cross-over protocol. Blood samples were collected both at rest, at the end of the test, and during passive recovery (5 min, 10 min, 15 min) for leptin (at rest), and blood lactate measurements. No significant changes in lean body mass, fat mass, and leptin were observed with SAL treatment in either group during the trial. Peak power was significantly increased (p < 0.05) after SAL intake in all subjects (T: 11.9 %; UT: 8.3 %) with a decrease in time to peak power with SAL compared to placebo (PLA) (p < 0.05). There was no change in total work performed and in fatigue indices with SAL compared to PLA. Blood lactate was significantly increased after SAL vs. PLA during the recovery (p < 0.05) in all subjects. The data demonstrate that the chronic administration of therapeutic levels of salbutamol increases maximal anaerobic power in man, irrespective of the subjects' training status. This study also rules out any implication of an anabolic effect in this improvement in performance during supramaximal exercise. Further studies are necessary to clarify the mechanisms involved.     

Contribution of energy systems during a Wingate power test.

Six men performed a total of 23 modified Wingate power tests against 5.5 kp (53.9 N) resistance on a Monark 864 ergometer. Breath-by-breath VO2 was measured using a SensorMedics 4400 metabolic cart. Peak anaerobic power (highest 5 s; mean(s.e.m.)) was 819(16) W (11.1(0.6) W kg-1) and anaerobic capacity (work in 30 s; mean(s.e.m.)) was 18.2(0.2) kJ (248(11) J kg-1). Contributions of ATP-PC, glycolytic and aerobic systems each 5 s were estimated. ATP-PC power (mean(s.e.m.)) peaked at 750(14) W (10.2(0.6) W kg-1) in the first 5 s; glycolytic power (mean(s.e.m.] peaked at 497(11) W (6.8(0.7) W kg-1) between 10 and 15 s into the test; aerobic power (mean(s.e.m.)) peaked at 157(5) W (2.1(0.3) W kg-1) during the last 5 s of the test, and VO2 exceeded 90% VO2peak Over the entire 30 s, aerobic contribution was 16%, glycolytic contribution was 56%, and ATP-PC contribution was 28%. It is concluded that glycolytic power peaks within the first 15 s of high power exercise; also, aerobic metabolism responds quickly during 'anaerobic' exercise and makes a significant contribution to the work performed.     

Ventilatory thresholds assessment from heart rate variability during an incremental exhaustive running test

The present study examined whether the ventilatory thresholds during an incremental exhaustive running test could be determined using heart rate variability (HRV) analysis. Beat-to-beat RR interval, V(.-)O (2), V(.-)CO (2) and V(.-) (E) of twelve professional soccer players were collected during an incremental test performed on a track until exhaustion. The "smoothed pseudo Wigner-Ville distribution" (SPWVD) time-frequency analysis method was applied to the RR time series to compute the usual HRV components vs. running speed stages. The ventilatory equivalent method was used to assess the ventilatory thresholds (VT1 and VT2) from respiratory components. In addition, ventilatory thresholds were assessed from the instantaneous components of respiratory sinus arrhythmia (RSA) by two different methods: 1) from the high frequency peak of HRV ( FHF), and 2) from the product of the spectral power contained within the high frequency band (0.15 Hz to fmax) by FHF (HF x FHF) giving two thresholds: HFT1 and HFT2. Since the relationship between FHF and running speed was linear for all subjects, the VTs could not be determined from FHF. No significant differences were found between respective running speeds at VT1 vs. HFT1 (9.83 +/- 1.12 vs. 10.08 +/- 1.29 km x h (-1), n.s.) nor between the respective running speeds at VT2 vs. HFT2 (12.55 +/- 1.31 vs. 12.58 +/- 1.33 km x h (-1), n.s.). Linear regression analysis showed a strong correlation between VT1 vs. HFT1 (R (2) = 0.94, p < 0.001) and VT2 vs. HFT2 (R (2) = 0.96, p < 0.001). The Bland-Altman plot analysis reveals that the assessment from RSA gives an accurate estimation of the VTs, with HF x FHF providing a reliable index for the ventilatory thresholds detection. This study has shown that VTs could be assessed during an incremental running test performed on a track using a simple beat-to-beat heart rate monitor, which is less expensive and complex than the classical respiratory measurement devices.     

Heart rate recovery from submaximal exercise in boys and girls

PURPOSE: To examine the changes in heart rate (HR) after two different submaximal exercise bouts in boys and girls. METHODS: Eleven boys (10.5 +/- 1.0 yr) and 10 girls (10.8 +/- 0.7 yr) participated in this study. Each child completed an initial graded exercise test to determine peak VO2. On subsequent and separate days, a 5-min submaximal exercise bout on a cycle ergometer was performed. One bout was conducted at 70 W, and the other bout corresponded to an intensity of 85-90% of peak VO2. VO2 and HR were measured during and after (1 min and 3 min). HR recovery responses from each submaximal exercise bout were analyzed using a group by time ANOVA, and Pearson-product correlations were determined between resting HR, peak VO2, and postexercise HR responses. RESULTS: HR in the boys was lower at the end of exercise and the first minute of recovery versus girls but not at the 3rd min of recovery. There were no differences in HR recovery after the relative exercise bout. Resting HR was significantly correlated with postexercise HR from both bouts (r = 0.52-0.69), whereas peak VO2 did not correlate to postexercise HR. ANCOVA using resting HR as the covariate eliminated the gender different noted with the recovery from the 70-W bout. CONCLUSIONS: In summary, postexercise HR responses differed between boys and girls when submaximal exercise was performed at an absolute work rate. When exercise was performed at a relative intensity, HR recovery responses were similar between the two groups. Resting HR appears to account for variations in postexercise HR better than peak VO2.     

不同运动强度下恢复期心率推测运动心率的探讨

目的：研究不同运动强度下恢复期心率随恢复时间的变化特征,探讨恢复期心率与运动心率的关系,建立恢复期心率推测运动心率的方法。方法以60名男兵为对象,在功率自行车上进行不同强度（20、40、60、80、100、120、140、160、180 W）的运动,每一运动强度持续6 min;受试者佩戴心率带,实时监测运动中及恢复期的心率。结果（1）运动心率与恢复期10,20,30,40,50,60 s的心率均存在显著性差异（P＜0．05）;（2）不同运动强度恢复期心率下降值的比较,20,40和60 W强度,80、100和120 W强度以及140、160和180 W强度3段各自比较均无显著差异;上述3段强度间相应恢复心率下降值比较有显著差异（P＜0．05）;（3）相同运动强度下不同时间（10、20和30 s）的单位时间恢复期心率下降值比较,0～10 s与10～20 s和20～30 s有显著差异（P＜0．05）,10～20 s和20～30 s无显著差异;（4）针对20～60 W、80～120 W、140～180 W 3段运动强度的运动心率和恢复期10～30 s时的恢复心率,回归分析得到运动心率与恢复期心率和恢复时间的回归方程。结论不同运动强度的恢复期心率随时间的变化规律存在异同;可依不同强度的运动心率推测方程,由恢复期心率和时间推测运动心率;恢复期心率和恢复时间的最佳测量时间是运动结束后10～30 s。     

Heart rate variability during night sleep and after awakening in overtrained athletes

PURPOSE: This study was conducted to test the hypothesis of autonomic imbalance in overtrained athletes during sleep and after awakening with analyses of heart rate variability (HRV) and nocturnal urine stress hormones. METHODS: We examined 12 athletes diagnosed to be severely overtrained (OA, 6 men and 6 women, mean age (+/-SD) 25 +/- 7 yr) and 12 control athletes (CA, 6 men and 6 women, mean age 24 +/- 5 yr). Overtraining diagnosis was further supported by higher perceived stress in OA than in CA (24.8 +/- 10.8 vs 15.3 +/- 5.5, P < 0.05). HRV was analyzed with time and frequency domain methods from RR intervals (RRI) recorded during sleep and after awakening. Nocturnal urine stress hormones were analyzed by liquid chromatography. RESULTS: No differences were found in HRV or stress hormones during night sleep. After awakening, the standard deviation of RRI (84 +/- 31 vs 116 +/- 41 ms, P < 0.05) and low-frequency power of RRI (2153 +/- 2232 vs 4286 +/- 2904 ms, P < 0.05) were lower in OA than in CA. From sleep to after awakening, the coefficient of variation of RRI decreased more in OA than in CA (from 11.8 +/- 3.3 to 7.7 +/- 2.5%, P < 0.001 vs from 11.9 +/- 1.8 to 10.0 +/- 2.5%, P < 0.01, respectively, interaction P < 0.05). CONCLUSION: The present findings suggest that in OA, cardiac autonomic modulation is at the level of control athletes during sleep, but the parasympathetic cardiac modulation is slightly diminished after awakening. Further investigations should concentrate on autonomic responses to different challenges, such as awakening in the present study.     

Heart rate variability during exercise performed below and above ventilatory threshold

PURPOSE: To examine whether differences in heart rate variability (HRV) can distinguish sub- from supra-ventilatory-threshold exercise and whether the exercise duration at supra-threshold intensity alters cardiorespiratory synchronization. METHODS: Beat-to-beat RR interval, VO2, VCO2, VE, and blood lactate concentration of 11 healthy well-trained young subjects were collected during two exercise tests: 1) a moderate-intensity test: 15 min performed below the power at ventilatory threshold (pVT); and 2) a heavy-intensity test: above pVT until exhaustion. Fast Fourier transform, smoothed pseudo Wigner-Ville distribution, and complex demodulation were applied to RR time series. RESULTS: 1) Moderate exercise shows a prevalence of low-frequency (LF) spectral energy compared with the high-frequency (HF) one (LF = 80 +/- 10% vs HF = 20 +/- 10%, P < 0.001), whereas the reverse is observed during heavy exercise (LF = 11 +/- 8% vs HF = 89 +/- 8%, P < 0.001). 2) During heavy exercise, the HF amplitude and the tidal volume (Vt) remained constant, whereas the breathing frequency (BF) increased (BF: 0.70 +/- 0.18 vs 0.93 +/- 0.31, P < 0.01) and mean RR decreased (342 +/- 15 vs 317 +/- 16, P < 0.01). Despite the RR series and the breathing signal remaining synchronized, HR/BF ratio decreased and stabilized at 3 RR for one breathing cycle, whatever the initial ratio. CONCLUSION: 1) HRV allows us to differentiate sub- from supra-ventilatory-threshold exercise and 2) exercise duration at supra-threshold intensity does not alter the cardiorespiratory synchronization.     

新老伞兵跳伞训练心率变异性研究

目的：观察新老伞兵跳伞过程心率变异性指标的变化,探讨新老伞兵跳伞过程心理应激的变化特点。方法：跳伞训练的新兵30名,老兵20名,跳伞当天佩戴飞行员飞行生理参数记录检测仪连续动态记录心电信号,对其在驻地、机场、机上的短时程心率变异性指标进行分析。结果：随着跳伞时间的临近,新老伞兵心率变异性指标HF、HFNU出现降低,LFNU和LF/HF出现升高。与新兵不同的是,老兵在机场和机上的HF、HFNU及LFNU变化不明显,老兵在驻地和机上的HF、HFNU均高于新兵,LFNU和LF/HF均低于新兵。结论：跳伞训练中新兵和老兵相比,心理应激水平较高,变化较大。     

Heart rate variability in patients with allergic rhinitis

Considering the role of autonomic imbalance in the pathogenesis of hypersensitivity reactions, we evaluated the autonomic system through time-domain analysis of heart rate variability (HRV) in patients with allergic rhinitis. Twenty-four patients with allergic rhinitis and 22 healthy subjects (mean age, 41 +/- 8 years and 37 +/- 9 years, respectively) were enrolled in the study. The diagnosis of allergic rhinitis was based on the history, symptoms, and skin prick tests results. Twenty-four-hour ambulatory electrocardiographic recordings were obtained, and the time-domain indices were analyzed. Analysis of HRV revealed that the SD of normal RR intervals, SD of successive differences in normal cycles, and HRV triangular index were not significantly different between the groups, but the root mean square successive difference, number of RR intervals exceeding 50 milliseconds, and percentage difference between adjacent normal RR intervals exceeding >50 milliseconds were significantly greater in the study group, compared with the control group. Our findings showed that HRV indices, which predict parasympathetic predominance, were increased in patients with allergic rhinitis. This finding shows that vagal activation is present not only in the nose but also in other systems, including the cardiovascular system.     

Effect of short recovery intensities on the performance during two Wingate tests

PURPOSE: To assess the effects of the intensity of short recoveries on performance by a Wingate test and on the deoxyhemoglobin variations. METHODS: Twelve male subjects performed a graded test and three sessions of repeated all-out tests with different recovery natures. The repeated all-out tests included two sprints: a 15-s Wingate test followed by a 30-s Wingate test. The recovery between the two was 15 s in duration and was either passive, active at 20% of maximal aerobic power, or active at 40% of maximal aerobic power. Changes in deoxyhemoglobin were measured using by the near-infrared spectroscopy technique. RESULTS: Mean power (517 +/- 26 W) and peak power (1085 +/- 153 W) of the 30-s Wingate test performed after passive recovery were significantly higher (P < 0.05) than mean power and peak power performed after active recovery at 20% (484 +/- 30 and 973 +/- 112 W, respectively) and 40% of maximal aerobic power (492 +/- 35 and 928 +/- 116 W, respectively). Deoxyhemoglobin variations were significantly higher (P < 0.05) during the passive recovery (12.8 +/- 5.3 microM) than during the active recovery conditions at 20% (4.3 +/- 2.6 microM) and 40% of maximal aerobic power (3.9 +/- 2.6 microM). CONCLUSION: These results demonstrate that when two Wingate tests are performed almost successively but with a short recovery between the two, passive recovery is more appropriate than active recovery to restore the performance level.     

Pre- and post-season heart rate variability in adolescent cross-country skiers

To investigate the effects on cardiac autonomic control after a competitive cross-country skiing season, 9 females and 8 males, 16-19 years old, performed tilt-table heart rate variability (HRV) recordings and incremental treadmill tests before (August), and after (April the following year) the most intensive period of training and competition. Spectral analysis of HRV showed increased total variability at rest and reduced low frequency variability in the tilted position (LFtilt) at the second test (P<0.05). The female subgroup showed consistently higher high frequency (HF) and total heart rate variability than males. Total run time (RunT) increased from 18.5+/-1.9 min to 19.4+/-1.7 min (mean+/-SD) in the entire group (P<0.05), while VO2max only showed a non-significant increase (0.05相似文献   

Heart rate variability in rats acclimatized to high altitude

The aims of this study were to relate heart morphology and functions changes to heart rate variability (HRV) components after acclimatization to high altitude and to define whether preadaptation to hypoxia could modulate HRV responses to acute hypoxic stress. Doppler-echocardiographic studies of the left ventricle were performed in female Wistar rats before, during, and after a 10-week exposure to moderate hypobaric hypoxia (CH rats, approximately 4000 m simulated) or normoxia (N rats, approximately 55 m). Right ventricular morphology and function and pulmonary artery pressure were evaluated using heart catheterization. Spectral analysis of HRV was studied after exposure in conscious unrestrained rats in normoxia and during acute hypoxic stress. Necropsy right ventricular hypertrophy and intraventricular and pulmonary artery hypertension were found in CH rats compared with N rats. Echocardiographic left ventricular morphology and functions were similar between the groups after exposures. Compared to the control group, CH rats had similar heart rates and HRV components when measured in normoxia. During acute hypoxic stress, HRV decreased in all rats, but less in CH rats. These results support the hypothesis that long-term mild hypoxia may moderate sympathetic activation induced by acute hypoxia and that right ventricular hypertrophy cannot be the direct cause of such a shift in sympathovagal nerve interaction during acute hypoxic stress.     

急性心肌梗死患者心率变异性临床分析

对８４例急性心肌梗死患者进行心率变异性分析。应用２４ｈ磁带记录器。进行２４ｈＨｏｌｔｅｒ心电图记录，对记录磁带采用电子计算机分析，对急性心肌梗死的病变范围和程度及预后进行估计。     

Diurnal evolution of cycling biomechanical parameters during a 60‐s Wingate test

The purpose of this study was to assess the evolution of pedaling kinetics and kinematics during a short‐term fatigue cycling exercise at two times of day. Twenty active male subjects were asked to perform a 60‐s Wingate test against a constant braking resistance during two experimental sessions at 06:00 and 18:00 hours, i.e., very close to the hours of core temperature values, which are, respectively, the lowest and the highest. The results showed that the fatigue index was higher (P<0.05) at 18:00 hours (71.4%) than at 06:00 hours (69.2%) and power output was higher (P<0.05) in the evening than in the morning during the first 20 s of the test, after which no difference was observed. Taken together, these results showed a greater progression of fatigue in the evening than in the morning. The diurnal variations in performance and fatigue were associated (P<0.001) with diurnal changes in cycling kinematic parameters, characterized by a reduction in the range of motion of the ankle angle in the evening. These findings show that a time‐of‐day effect on movement patterns occurs during an anaerobic cycling exercise and that this phenomenon has a direct influence on performance and fatigue.     

Heart rate variability, cardiac mechanics, and subjectively evaluated stress during simulator flight

The effects of a simulator flight task on the heart rate variation (HRV) and hemodynamic variables were studied in nine pilots with instrument flight ratings. An electrocardiogram (ECG), phonocardiogram (PCG), and impedance cardiogram (ICG) were recorded continuously during three successive flights. Indices of HRV, power spectra, and autocorrelograms were computed from the R-R interval signal. Stroke volume (SV), cardiac output (CO), and systolic time intervals (STI) were determined by means of the ECG, PCG, and ICG. A scaling method for a subjective evaluation of tiredness, effort, and success during the flight was used. The repeats of the flight task decreased the heart rate (HR), CO, and cardiac index (CI). The different phases of the flight altered the HR (mean 97 min-1, S.E.M. 4 min-1), total HRV (RMSM) (mean 33 ms, S.E.M. 5 ms), and the periodic HRV. Subjectively, the pilots felt only moderate stress. The subjectively evaluated tiredness was significantly associated with the STI. Moderate informative stress in the flight simulator affected the chronotropic parameters of the heart. The inotropic state of the heart was not affected by the different phases of the flight but possibly by the diminishing sympathetic drive with accommodation during the repeats.