Progressive Maximal Exercise Test Research Articles

How can the pain sensitivity to be affected by maximal progressive exercise test during pregnancy?

The multidimensional etiology of pain may explain the beneficial effects of regular physical activity, as evidenced by increased pain tolerance. Physically active people find it easier to exert themselves, which enables them to increase their physical activity, which in turn leads to a reduction in pain. However, no study investigated the physical activity and exercise tests as modulators of pain sensitivity in pregnant women. Therefore, this study aimed to investigate the changes in pain perception in pregnant women during pregnancy, with a particular interest in the effects of maximal progressive exercise test (CPET) and self-performed physical activity (PA). Thirty-one women with an uncomplicated singleton pregnancy (aged 23-41 years; M = 31.29, SD = 4.18) were invited to participate in pain sensitivity measurements before and after CPET twice during pregnancy (with an 8-week break). We found that pregnant women had a significantly lower pain threshold after a maximal exercise test than before, regardless of whether the test was performed in the second or third trimester of pregnancy. This effect was most pronounced in women with low levels of physical activity. Second, women with high physical activity had higher pain tolerance than women with moderate and low physical activity. In addition, physical activity levels predicted changes in pain tolerance over the course of pregnancy, with negative changes in women with low physical activity and positive changes in women with moderate physical activity. Finally, these associations were not reflected in differences in the subjective pain experience.

Changes in pain perception during pregnancy after one-time maximal physical exertion and an 8-week high-intensity interval training.

Background: Pain, a subjective sensation, poses a great challenge to the human body as a stressor. There is empirical evidence that moderate to intense physical activity increases pain tolerance and this may be critical during pregnancy for optimal pregnancy, fetal development, and delivery. To the best of our knowledge, it is the first study examining the changes in pain perception in pregnant women after a maximal progressive exercise test and after 8weeks of high-intensity interval training (HIIT). Methods: Thirty-five women with uncomplicated singleton pregnancies between 13 and 28weeks of gestation participated in the study. The HIIT intervention was developed in accordance with the recommendations and available data on HIIT during pregnancy. The maximal progressive cardiopulmonary exercise test was performed on a cycle ergometer with an electronically controlled load. Pressure pain threshold and pressure pain tolerance were measured with an algometer. Results: We found significant effects of the maximal exercise test and high-intensity interval training, such that the pregnant women had higher pain tolerance after the maximal exercise test than before and after the high-intensity interval training than the baseline. Conclusion: Our results suggest that post-exercise analgesia may be important in pregnant women and that high-intensity interval training appears to be beneficial for pregnant women to improve their pain tolerance while being obstetrically safe. Increased pain tolerance before labor could lead to better management of pain during labor and in the postpartum and lactation periods. Increasing pregnant women's awareness of this issue can improve their wellbeing and provide more comfort during labor.

#3594 CHANGES IN ALBUMINURIA AND KIDNEY FUNCTION AFTER 8 WEEK HIGH-INTENSITY INTERVAL TRAINING PROGRAM IN 2ND AND 3RD TRIMESTER OF PHYSIOLOGICAL PREGNANCY

Abstract Background and Aims Physical exercise is the best prophylaxis of many disorders and should be continued during uncomplicated pregnancy. Several studies suggested that most pregnant women had no contraindications to perform intensive exercises. In recently published studies the beneficial effect of high-intensity interval training (HIIT) on both mental health and reduction of excessive weight gain during pregnancy has been demonstrated. The knowledge regarding kidney function after exercise in pregnancy is very scarce and only few studies concerning this topic were published. The aim of this study was to estimate changes in markers of kidney function in healthy pregnant exercising women. Changes after single intensive exercise and after 8 week training program were analyzed. Method The group of 36 women in 2nd and 3rd trimester of pregnancy were recruited to the study. At the beginning of the study all participants had normal kidney function (serum creatinine level below 0.6 mg/dl) and albuminuria (uACR below 30 mg/g) in rest. 19 women participated in 8-week HIIT program and 17 women in 8-week educational program (EDU group). Before and after 8 week training and education programs a progressive maximal exercise test on cyclometer was performed. Several biochemical measurements were performed. Results Women from both groups revealed mild changes concerning kidney function in rest, typical for physiological pregnancy (e.g. low sodium, creatinine and uric acid levels). After progressive maximal exercise test some unexpected findings were found: the fractional excretion of urea and uric acid increased (FeUrea from 41.25 to 50.05%; FeUA from 7.18 to 8.04%) and serum uric acid decreased significantly (sUA from 3.35 to 3.28mg/dL). Other changes after short exercise were typical: significant increase of uACR (from 5.12 to 9.43mg/g), serum creatinine (from 0.52 to 0.56mg/dL) and urea (from 16.45 to 21.65 mg/dL), among others. The 8-week HIIT training program did not change kidney function in rest. In both groups a significant increase of eCrCl and sUA were observed. The interesting observation was that uACR increased significantly only in EDU group. Conclusion Changes in kidney function after short intensive exercise in pregnancy were typical for healthy subjects, but there was no negative impact on markers of renal hypoperfusion. It was probably related to increased renal blood flow occurring in healthy pregnancy. The supervised 8-week HIIT training program had no negative impact on kidney function. The possible positive impact of this training on albuminuria was suggested.

Novel Computerized Method for Automated Determination of Ventilatory Threshold and Respiratory Compensation Point.

Introduction: The ventilatory threshold (named as VT1) and the respiratory compensation point (named as VT2) describe prominent changes of metabolic demand and exercise intensity domains during an incremental exercise test.Methods: A novel computerized method based on the optimization method was developed for automatically determining VT1 and VT2 from expired air during a progressive maximal exercise test. A total of 109 peak cycle tests were performed by members of the US astronaut corps (74 males and 35 females). We compared the automatically determined VT1 and VT2 values against the visual subjective and independent analyses of three trained evaluators. We also characterized VT1 and VT2 and the respective absolute and relative work rates and distinguished differences between sexes.Results: The automated compared to the visual subjective values were analyzed for differences with t test, for agreement with Bland–Altman plots, and for equivalence with a two one-sided test approach. The results showed that the automated and visual subjective methods were statistically equivalent, and the proposed approach reliably determined VT1 and VT2 values. Females had lower absolute O2 uptake, work rate, and ventilation, and relative O2 uptake at VT1 and VT2 compared to men (p ≤ 0.04). VT1 and VT2 occurred at a greater relative percentage of their peak VO2 for females (67 and 88%) compared to males (55 and 74%; main effect for sex: p < 0.001). Overall, VT1 occurred at 58% of peak VO2, and VT2 occurred at 79% of peak VO2 (p < 0.0001).Conclusion: Improvements in determining of VT1 and VT2 by automated analysis are time efficient, valid, and comparable to subjective visual analysis and may provide valuable information in research and clinical practice as well as identifying exercise intensity domains of crewmembers in space.

Markers of Cardiac Autonomic Function During Consecutive Day Peak Exercise Tests in People With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) have been shown to exhibit altered ventilatory characteristics on the second of two progressive maximal cardiopulmonary exercise tests (CPET) performed on consecutive days. However, maximal exercise can exacerbate symptoms for ME/CFS patients and cause significant post-exertional malaise. Assessment of heart rate (HR) parameters known to track post-exertional fatigue may represent more effective physiological markers of the condition and could potentially negate the need for maximal exercise testing. Sixteen ME/CFS patients and 10 healthy controls underwent a sub-maximal warm-up followed by CPET on two consecutive days. Ventilation, ratings of perceived exertion, work rate (WR) and HR parameters were assessed throughout on both days. During sub-maximal warm-up, a time effect was identified for the ratio of low frequency to high frequency power of HR variability (p=0.02) during sub-maximal warm-up, and for HR at ventilatory threshold (p=0.03), with both being higher on Day Two of testing. A significant group (p<0.01) effect was identified for a lower post-exercise HR recovery (HRR) in ME/CFS patients. Receiver operator characteristic curve analysis of HRR revealed an area under the curve of 74.8% (p=0.02) on Day One of testing, with a HRR of 34.5bpm maximising sensitivity (63%) and specificity (40%) suggesting while HRR values are altered in ME/CFS patients, low sensitivity and specificity limit its potential usefulness as a biomarker of the condition.

Absence Of Histidine Dipeptides Does Not Affect Muscle Contractile Proprieties: Study With Carns1 Knockout Rats

Carnosine and anserine are a histidine-containing dipeptides (HCDs) abundantly expressed in the skeletal muscle. Although several properties have been ascribed to HCDs (e.g., H+ buffering and Ca2+ handling), it remains unknown whether it is relevant for muscle contractility in vivo. PURPOSE: To investigate the impact of the absence of HCDs on muscle contractile properties assessed in vivo. METHODS: We developed a novel CARNS1 knockout (KO) rat strain using the CRISPR/Cas9 technology to generate rats that are fully devoid of HCDs, and thus examine its role on muscle function. Male wild-type (WT) and KO rats (4 months-old) were used. We examined whether CARNS1 KO impacted: i) exercise tolerance in a progressive maximal treadmill exercise test; ii) the in vitro muscle buffering capacity using the titration method; iii) force generation, contractile properties and tolerance to fatigue using the in situ assessment of the tibialis anterioris function evoked by electrical stimulation of the sciatic nerve. Data are presented as mean ± SD. Fatigue test were analysed with mixed models. For all other variables, Welch’s two-sample t-tests for unequal sample sizes were used to compare the groups (RStudio v.4.0.0). RESULTS: Exercise tolerance was similar between KO and WT (KO: n = 6, WT: n = 4; p = 0.34). We next determined the in vitro buffering capacity of skeletal muscle extracts, which confirmed no effect of the absence of HCDs on muscle buffering capacity (n = 15 per group; p = 0.85). The absence of HCDs did not impact muscle resistance to fatigue (KO: n = 10, WT: n = 7; p = 0.37), peak force attained in single twitch and in maximal tetanic contractions, as well as time to peak force and half-relaxation time (KO: n = 10/WT: n = 7; all p > 0.05) (Table). CONCLUSION: HCDs absence did not affect exercise capacity, force generation, fatigability, and the in vitro buffering capacity, indicating that carnosine and anserine are not essential for pH regulation or muscle function. Supported by FAPESP and CAPES

Influence of Acute Aerobic Exercise on 24-hour Ambulatory Central Blood Pressure

Ambulatory central blood pressure (cABP) assessed for 24-hours is a relatively new measurement that may be predictor of cardiovascular disease (CVD). Acute bouts of exercise lower peripheral blood pressure; however, it is currently unknown if an acute bout of vigorous exercise reduces 24-hour cABP. PURPOSE: To examine the response of cABP over 24 hours after an acute bout of aerobic exercise. METHODS: Apparently healthy adults (N=10; 6 males; age 25.9±1.8 years; body mass index 25.4±0.6 kg/m2; VO2max 46.1±2.7 ml/kg/min) completed two trials in a randomized order. Trials consisted of a progressive maximal treadmill exercise test to assess VO2max or a non-exercise control. During each trial, participants wore an ambulatory BP (ABP) monitor to record brachial and central BP variables over 24 hours. Hemodynamic variables between trials were analyzed as mean for 24 hours and by time of day; Daytime (0800-2200 hours), and Nighttime (2200- 0800 hours). Dependent t-test were used to compare 24-hour averages between control and exercise. A 2-way ANOVA with repeated measures was performed to examine time of day differences between trials. RESULTS: Over the course of 24 hours, average brachial systolic BP (bSBP) (119.6 ±2.2 vs. 122.0 ±2.5 mmHg) central systolic BP (cSBP) (108.1 ± 2.2 vs. 111.2 ± 2.4 mmHg), and mean arterial pressure (MAP) (86.9 ± 1.5 vs. 89.4 ± 1.9 mmHg) were lower (p<0.05) after exercise compared to control. A main effect for time (p<0.05) indicated that bSBP, bDBP, brachial pulse pressure, MAP, cSBP, and cDBP, were lower during nighttime compared to day time, independent of exercise. CONCLUSION: A single, vigorous bout of aerobic exercise lowers ambulatory central hemodynamics for at least 24 hours. These novel findings provide insight into the regulatory effects of exercise on blood pressure.

Comparison Of Recovery Measures Following Cardiorespiratory Fitness Testing In Young Children

Post exercise heart rate recovery measures have been used as a predictor of fitness and morality in adult populations. Less is known about the predictive value of oxygen consumption and heart recovery responses to clinical and field cardiorespiratory fitness testing in young children. PURPOSE: To compare oxygen uptake (VO2; ml·kg-1·min-1) and heart rate (HR; beats·min-1) recovery responses (mean ± SD) from the FitnessGram Progressive Aerobic Cardiovascular Endurance Run (PACER) test to recovery measures from a progressive maximal graded exercise test (GXT; treadmill) in 17 (9 boys) young (10-11 yr old) children. METHODS: Subjects completed the PACER and GXT in a randomized order 1 week apart while wearing a HR monitor and portable oxygen analyzer. VO2 and HR recovery measures were determined at 1, 3 and 5 mins post completion of the PACER and GXT. RESULTS: There were no significant mean VO2 measures between the PACER and GXT VO2 at 1 min (14.5 ± 3.1 vs 16.1 ± 3.6), 3 min (8.0 ± 1.4 vs 7.9±1.3), or 5 min (7.3 ± 1.4 vs 7.2 ± 1.6) of recovery. The GXT recovery HR (149.0 ± 31.0) recovery was significantly (p <0.05) greater at 1 minute than the PACER recovery HR (136.0 ± 17.0), however there was no significance between the GXT and PACER HR at 3 min (115.2 ± 9.1 vs 110.8 ± 11.7) or at 5 min (108.5 ± 7.7 vs 107.1 ± 10.0) of recovery. CONCLUSIONS: The PACER resulted in similar absolute cardiorespiratory recovery responses in young children when compared with a criterion fitness test. Supported by the University of Kentucky Pediatric Exercise Physiology Laboratory Endowment

Measurement of the maximum oxygen uptake V̇o2max: V̇o2peak is no longer acceptable.

The maximum rate of O2 uptake (i.e., V̇o2max), as measured during large muscle mass exercise such as cycling or running, is widely considered to be the gold standard measurement of integrated cardiopulmonary-muscle oxidative function. The development of rapid-response gas analyzers, enabling measurement of breath-by-breath pulmonary gas exchange, has facilitated replacement of the discontinuous progressive maximal exercise test (that produced an unambiguous V̇o2-work rate plateau definitive for V̇o2max) with the rapidly incremented or ramp testing protocol. Although this is more suitable for clinical and experimental investigations and enables measurement of the gas exchange threshold, exercise efficiency, and V̇o2 kinetics, a V̇o2-work rate plateau is not an obligatory outcome. This shortcoming has led to investigators resorting to so-called secondary criteria such as respiratory exchange ratio, maximal heart rate, and/or maximal blood lactate concentration, the acceptable values of which may be selected arbitrarily and result in grossly inaccurate V̇o2max estimation. Whereas this may not be an overriding concern in young, healthy subjects with experience of performing exercise to volitional exhaustion, exercise test naïve subjects, patient populations, and less motivated subjects may stop exercising before their V̇o2max is reached. When V̇o2max is a or the criterion outcome of the investigation, this represents a major experimental design issue. This CORP presents the rationale for incorporation of a second, constant work rate test performed at ~110% of the work rate achieved on the initial ramp test to resolve the classic V̇o2-work rate plateau that is the unambiguous validation of V̇o2max The broad utility of this procedure has been established for children, adults of varying fitness, obese individuals, and patient populations.

Preparatory training attenuates drastic response of the insulin-like growth factor binding protein 1 at the point of maximal oxygen consumption in handball players

BackgroundIntensive exercise changes physiological need for glucose and several biochemical pathways responsible for its metabolism response. Among them are those which involve insulin, insulin-like growth factor (IGF-1), and IGF-binding proteins (IGFBPs). Different types and degrees of exercise, as well as an athlete's fitness, may induce a range of responses regarding concentrations and time needed for the alteration. The idea of the work was to find out whether and how insulin/IGF axis responds to additional physical activity in the already trained subjects and if so, is the adaptation potentially beneficial from the aspect of metabolic control. MethodsThe effect of 4-week intensive training on campus (preparatory training) on the levels of insulin, IGF-1, and IGFBPs during maximal progressive exercise test (MPET) on a treadmill was compared to the results obtained during MPET conducted after a regular training season of a female elite handball team (n = 17, age: 17 ± 1 years, height: 171 ± 8 cm, weight: 65 ± 8 kg, body mass index: 22 ± 1 kg/m2 at the beginning of the study; there were no significant changes at the end). Serum samples were obtained from players immediately before the test (basal), at the end of the test after reaching the point of maximal oxygen consumption (VO2max), and after recovery. ResultsThe concentration of insulin decreased at VO2max, but remained higher in players after preparatory training (12.2 ± 2.5 mU/L vs. 8.9 ± 4.4 mU/L, p = 0.049). The level of IGFBP-1 decreased in players at VO2max in either case of training, but it remained much higher in tests performed after the preparatory regime than before (p = 0.029). Concentrations of IGF-1, IGFBP-2, -3, and -4 did not change significantly. ConclusionThe inverse relation between insulin and IGFBP-1 was lost during MPET, as these 2 molecules changed in the same direction. The results obtained suggest less severe stress-induced depression of insulin and IGFBP-1 after preparatory training. But another metabolic mechanism cannot be excluded, and that is potentially impaired insulin sensitivity resulting in higher level of IGFBP-1.

Effects Of Different PUFA Supplementation On Inflammatory Response Markers In Young Soccer Players

AbstractConsidering the limited knowledge regarding the effects of n-3 and n-6 PUFAs on the inflammatory response during physical activity, we aimed to evaluate the level of pro- and anti-inflammatory cytokines in young soccer players before and after a maximal physical load test at the beginning and end of a two-month training process. The study included 75 young footballers from Football School “Kragujevac,” who were followed during the two-month training programme. The subjects were divided into the following groups: 1) control group (consumed a standard diet); 2) group that consumed fish oil (2500 mg of n-3 PUFAs per day); 3) group that consumed nutritional sunflower oil (2500 mg of n-6 PUFAs daily). The maximal progressive exercise test was performed using a treadmill belt. Venous blood samples were drawn 4 times for the determination of cytokine levels (IL-6 and TNF-α): before and after the exercise load test before the two-month training programme (initial measurement) and immediately before and after the exercise load test after the two-month training programme (control measurement). Supplementation with fish oil (n-3) has been associated with reduced levels of IL-6 compared with the initial values. After an acute bout of exercise, n-3 PUFAs did not show a significant effect on inflammatory marker dynamics, whereas n-6 PUFAs slightly stimulated the production of TNF-α.

Impaired Skeletal Muscle Oxygenation and Exercise Tolerance in Pulmonary Hypertension.

Limb muscle dysfunction is documented in pulmonary arterial hypertension (PAH), but little is known regarding muscle oxygen (O2) supply and its possible effects on exercise tolerance in PAH. Ten patients with PAH and 10 matched controls underwent progressive maximal cardiopulmonary exercise test, voluntary and nonvolitional dominant quadriceps muscle strength measures, and nondominant quadriceps biopsy to assess maximal oxygen uptake, muscle function, and lower limb fiber type and capillarity, respectively. Both groups then performed normoxic and hyperoxic submaximal intensity exercise protocol at the same absolute workload during which muscle O2 supply was assessed by measuring changes in myoglobin-deoxyhemoglobin level (Δ[Mb-HHb]) and tissue oxygenation index in the dominant quadriceps using near-infrared spectroscopy. Changes in cardiac output, estimated systemic O2 delivery, and systemic O2 saturation were also assessed noninvasively throughout both submaximal exercises. Patients with PAH displayed lower maximal oxygen uptake (P < 0.01), skeletal muscle strength (P < 0.05), and capillarity (P = 0.01). Throughout the normoxic submaximal exercise protocol, Δ[Mb-HHb] (P < 0.01) was higher whereas changes in tissue oxygenation index (P < 0.01) and systemic O2 saturation (P = 0.01) were lower in patients with PAH compared with those in controls. Conversely, changes in cardiac output and estimated systemic O2 delivery were similar between groups. Muscle oxygenation remained unchanged with O2 supplementation. Among variables known to influence tissue oxygenation, only quadriceps capillarity density correlated with Δ[Mb-HHb] (r = -0.66, P < 0.01), which in turn correlated with maximal oxygen uptake (r = -0.64, P < 0.01), 6-min walked distance (r = -0.74, P = 0.01), and both voluntary (r = -0.46, P = 0.04) and nonvolitional (r = -0.50, P = 0.02) quadriceps strength. Capillary rarefaction within the skeletal muscle influences exercise tolerance and quadriceps strength at least partly through impaired muscle oxygen supply in PAH.

Influence of cardiorespiratory fitness on PPARG mRNA expression using monozygotic twin case control.

The influence of cardiorespiratory fitness (VO2max) on anthropometric variables and PPARG mRNA expression was investigated. Monozygotic twin pairs aged 11–18 years were grouped into discordant (D) and concordant (C) high and low VO2max groups. VO2max was determined by progressive maximal exercise test on treadmill with gas exchange analysis. Body mass (BM), BMI, waist circumference (WC), triceps (TR), and subscapular (SB) skinfold thicknesses were measured. Twins from the discordant group had differences in VO2max values (D-high = 45.9 ± 10.0 versus D-low = 32.4 ± 10.6 mL·kg−1·min−1, P = 0.025), while no differences were found in the concordant group (C-high = 42.4 ± 9.2 versus C-low = 38.8 ± 9.8 mL·kg−1·min−1, P = 0.952). In discordant group, VO2max was negatively correlated with TR + SB (r = −0.540, P = 0.021) and positively correlated with PPARG expression in leukocytes (r = 0.952, P = 0.001). Moreover, PPARG expression was directly correlated with BM (r = 0.714, P = 0.047) and height (r = 0.762, P = 0.028). In concordant twins, VO2max was inversely correlated with BM (r = −0.290, P = 0.027), BMI (r = −0.472, P = 0.001), WC (r = −0.426, P = 0.001), and TR + SB (r = −0.739, P = 0.001). Twins D-high had 1.78-fold greater PPARG expression when compared with twins D-low (P = 0.048). In conclusion, the cardiorespiratory fitness may modulate PPARG expression in childhood and adolescence, independently of the genetic background.

Relative and absolute reliability of the crossover and maximum fat oxidation points during treadmill running

Summary Objective was to investigate the relative and absolute reliability of cross over (COP) and maximal lipid oxidation (LIPOX max ) points during treadmill running in sedentary healthy subjects. Subjects and methods Twelve sedentary subjects (aged 20.5 ± 1.0 years) performed in random sequence two submaximal graded exercise tests to test the criterion standard for reliability of metabolic tests on treadmill over a time interval of four days. Maximal oxygen intake and maximal aerobic velocity (MAS) were assessed, using a progressive maximal exercise test on a treadmill (Cosmed T170, Germany). Subjects performed two submaximal graded exercise tests (T1 and T2), based on the measured maximal aerobic speed (MAS). Respiratory parameters, the COP and the LIPOX max points, and the maximal fat oxidation rate (MFO) were measured during these submaximal protocols. Results We found no significant differences between T1 and T2 with respect to COP, LIPOX max and the MFO. Intra-class correlation (ICC) measures of relative reliability were 0.91 for COP, 0.84 for LIPOX max and 0.803 for MFO. Coefficients of variation (CV) for COP and MFO values between T1 and T2 were low, falling well within the 10% criterion of absolute reliability (CV COP = 9.0%, CV MFO = 2.6%). However, LIPOX max showed greater variability (CV= 15.2%). The standard error of measurement ± minimal detectable change (SEM ± MDC) values were 0.89 ± 2.08 mL.min −1 .kg −1 , 1.79 ± 4.17 mL.min −1 .kg −1 and 23.74 ± 65.80 mg.min −1 for COP, LIPOX max and MFO, respectively. The mean differences (bias) ± 95% limits of agreement (LOA) were 0.4 ± 5.9 mL.min −1 .kg −1 , –0.4 ± 8.8 mL.min −1 .kg −1 and 10.3 ± 104.05 mg.min −1 for COP, LIPOX max and MFO, respectively. Conclusion Our data shows that COP, LIPOX max , and MFO measurements on a treadmill, over a time interval of four days, are reproducible. These metabolic measurements could be used in sedentary subject to calibrate training intensity.

Effects of cardiovascular fitness and training history on heart rate variability before, during, and after a progressive maximal intensity exercise test (881.2)

Heart rate variability (HRV) is a non‐invasive clinical indicator of cardiovascular health. We sought to examine differences in HRV as a function of exercise choice, frequency, length of regular participation, and aerobic capacity. 83 men (age: 23 ± 4 yr; height: 181 ± 8 cm; body mass: 83 ± 12 kg) with varying exercise preferences participated in the investigation. Heart rate was monitored with a five‐lead electrocardiogram before, during, and after exercise. Each experimental stage was two minutes long: subjects sat, stood, and then cycled in 35 W increments until volitional failure, before sitting in recovery (heart rate max: 184 ± 13 BPM; max power output: 256 ± 54 W; estimated VO2peak 3.16 ± 0.63 [L ● Min ‐1]). Measures of HRV were provided by time domain, frequency, and non‐linear analyses. Principal component analysis was used to distinguish contributory factors for HRV; the reliability of this analysis was confirmed with Chronbach’s Alpha test. Despite the use of a seemingly homogenous sample of college students, our analysis indicated consistent differences in HRV. Specifically, HRV varied with exercise preferences (p蠄0.05), and higher aerobic capacity (determined by the cycle exercise test) was associated with significantly lower HRV (p蠄0.05). We conclude that the unique and specific health benefits of exercise may be reflected in HRV. While further work on long‐term training outcomes is needed, HRV may serve as an indicator of cardiovascular and neuronal adaptations to exercise.

Circadian Cycle and Its Influence on Parameters of Aerobic Training

<b>Objectives: </b>This study aims to evaluate the Influence of two distinct Periods of the day on maximal aerobic power in young Athletes mountain bike. Volunteers are the mountain bike Athletes, 37.83 ± 8.87 years, and underwent two progressive maximal exercise test on a cycle Ergometer at two times of day. Gauging the behavior glucose and heart rate. The verification of normality of data was performed by the Shapiro-Wilk test for analysis of variables was Adopted t test for paired samples. Statistical we Adopted an evidence for p <0.05. Results: Were the glucose threshold results not statistically significant. However trends indicating were there a better outcome in the evening. The maximal workload, maximal heart rate and glycemic load threshold. Conclusions: The results show trends on performance and circadian rhythm, and yet, the routine or team chosen for sensivity training appears to the circadian cycle.

The effects of five weeks of kickboxing training on physical fitness

the purpose of this study was to examine the effect of kickboxing training on physical fitness. 30 subjects were randomized into a kickboxing-group (n=15) and control group (n=15). Each group trained approximately 1-hour per day, three-times per a week during five weeks. Muscle-power (upper-body: bench-press-test, medicine-ball-test; lower-body: squat-jump and counter-movement-jump-test), flexibility, speed and agility, aerobic (progressive maximal exercise test), anaerobic fitness (Wingate test) and body composition were assessed before and after the training period. the kickboxing group showed significant improvement (p < 0.05) in upper-body muscle power, aerobic power, anaerobic fitness, flexibility, speed and agility after training whereas body composition, squat jump and counter movement jump (height, power and velocity components) did not change for both groups. kickboxing-practice was effective to change many physical variables. Thus, this activity can be useful for enhancing physical fitness, but complementary activities and/or nutritional interventions should be necessary.

Comparison of blood pro/antioxidant levels before and after acute exercise in athletes and non-athletes

The aims of our study were to assess the redox state of adolescent athletes and non-athletes both at rest and after acute exposure to physical load and to find relations between parameters of redox state and morphofunctional characteristics of subjects. 58 young handball players and 37 non-athletes were subjected to body composition analysis, measuring of maximal oxygen consumption and blood sampling immediately before and after a maximal progressive exercise test. At rest, athletes had significantly higher superoxide dismutase (SOD) and catalase (CAT) activity, higher levels of glutathione (GSH) and nitric oxide (NO) and lower levels of lipid peroxidation (TBARS) compared with non-athletes. A maximal exercise test induced statistically significant rise of superoxide anion radical (O2-), hydrogen peroxide (H2O2) and NO levels in non-athletes, while TBARS levels decreased. Athletes experienced the fall in NO levels and the fall in CAT activity. After exercise, athletes had significantly lower levels of O2- compared with non-athletes. Two way repeated measures ANOVA showed that the response of O2-, NO and TBARS to the exercise test was dependent on the sports engagement (training experience) of subjects. Significant correlations between morphofunctional and redox parameters were found. These results suggest that physical fitness affects redox homeostasis.

Different ventilatory responses to progressive maximal exercise test performed with either the arms or legs

OBJECTIVE:This study aimed to compare respiratory responses, focusing on the time-domain variability of ventilatory components during progressive cardiopulmonary exercise tests performed on cycle or arm ergometers.METHODS:The cardiopulmonary exercise tests were conducted on twelve healthy volunteers on either a cycle ergometer or an arm ergometer following a ramp protocol. The time-domain variabilities (the standard deviations and root mean squares of the successive differences) of the minute ventilation, tidal volume and respiratory rate were calculated and normalized to the number of breaths.RESULTS:There were no significant differences in the timing of breathing throughout the exercise when the cycle and arm ergometer measurements were compared. However, the arm exercise time-domain variabilities for the minute ventilation, tidal volume and respiratory rate were significantly greater than the equivalent values obtained during leg exercise.CONCLUSION:Although the type of exercise does not influence the timing of breathing when dynamic arm and leg exercises are compared, it does influence time-domain ventilatory variability of young, healthy individuals. The mechanisms that influence ventilatory variability during exercise remain to be studied.

The effects of progressive exercise on cardiovascular function in elite athletes: Focus on oxidative stress

Some side-effects of excessive physical training are ascribed to reactive oxygen species production. In this work we investigated the effects of progressively imposed maximal physical effort (levels I to V), using progressive maximal exercise test, on peripheral blood lactate, NO (through NO2-), superoxide anion (O2-) and methemoglobin (MetHb) in a group of 19 elite soccer players. Blood lactate (mmol/L) was increased (4.55, level V vs. resting level, 1.95). The basal production of NO2- was in the direct relation with O2 consumption. Significant increase (p<0.05) in O2- values at effort level I (4.18) as compared to the resting value (4.01), and the significant increase (p<0.01 or p<0.05) in the MetHb (%) was found between II (18.79) and III (19.63) or between II and IV (19.24) effort levels, respectively. The regression lines of NO2- and O2- crossed at the level of the respiratory compensation point (RC), suggesting that RC could be of a crucial importance not only in the anaerobic and aerobic metabolism but in mechanisms of signal transductions as well. The results could be of the theoretical interest and also useful in designing an athlete training strategy.