Beginning Of Exercise Research Articles

The algorithm used for the calculation of gas exchange affects the estimation of O2 uptake kinetics at the onset of moderate-intensity exercise.

At the start of a moderate-intensity square-wave exercise, after a short delay, breath-by-breath O2 uptake at the mouth is approximated to a mono-exponential function, whose time constant is considered matched to that of the O2 uptake of the working muscles. We compared the kinetic parameters obtained from the breath-by-breath gas exchange data yielded by the 'Independent-breath' algorithm (IND), which accounts for the changes in lung gas stores, with those obtained with the classical 'Expiration-only' algorithm (EXP). The two algorithms were applied on the same flow and gas fraction traces acquired on 10 healthy volunteers, performing 10 times the same moderate-intensity exercise transition. Repeated O2 uptake responses were stacked together and the kinetic parameters of a mono-exponential function were estimated by non-linear regression, removing the data pertaining to 1-s progressively longer initial periods (ΔTr ). Independently of ΔTr , the mean response time (time constant + time delay) obtained for the IND data was faster compared to the EXP data (∼43s vs. ∼47s, P<0.001), essentially because of shorter time delays. Between ΔTr =16s and ΔTr =29s, the time constants of the IND data decreased (30.7s vs. 28.0s, P<0.05; drop=10%), but less than those of the EXP data (32.2s vs. 26.2s, P<0.001; drop=23%); with the same ΔTr , the time constants of the two algorithms' data were not different (P>0.07). The different decrease in the time constant, together with the different mean response time, suggests that the data yielded by the two algorithms provide a different picture of the phenomena occurring at the beginning of the exercise.

Physical exercise as cytokine modulator in inflammatory immune response: a systematic review

Physical exercise contributes to maintain our health, through its role in inflammatory immune response. Cytokines are proteins that mediate communication between immune cells, either as pro- or anti-inflammation agents. Nonetheless, the dominance of pro- over anti-inflammatory cytokines during a workout, is harmful to health. This systematic review aimed at determining the effect of physical activity in modulating pro- and anti-inflammatory cytokines during immune response. Following Preferred Reporting Items for Systematic Reviews (PRISMA) guideline, literature searching was conducted in 3 databases which were PUBMED/MEDLINE, DOAJ and GARUDA, using keywords, citation tracking and snowballing. Inclusion and exclusion criterias were used to screen, while the Newcastle Ottawa Scale (NOS) was used to assess the quality of the articles. Data extraction and analysis were conducted descriptively. There were 376 articles identified, of which 329 were sorted and 82 were retrieved. Thirty articles underwent quality assessment, resulting to 12 inclusion studies. In conclusion, physical exercise influences the modulation of cytokine, whereby IL-6 and TNF-α (pro-) which increase at the beginning of exercise, are balanced by the increase of IL-10 (anti-inflammatory), which appears later in exercise or during recovery. For this purpose, physical exercise is recommended as a combination of aerobic and resistance exercise performed regularly at moderate intensity.

Time limit at maximal aerobic power, heart rate kinetics and performance in time-trial cycling test of 3 km

The performance of cyclists in short terms workouts can be associate with several factors, including the maximal aerobic power (MAP), heart rate (HR) and its kinetics parameters, and the capacity to tolerate maximal efforts to exhaustion (TLimMAP). Thereby, the main of this study was analyze the presumable relation among TLimMAP and performance in a time-trial cycling test of 3 km. (TT3km). Seven cyclists were involved in this study, performing the following tests with a minimum interval of 48h: (1) initial familiarization and anthropometric evaluation, (2) maximal progressive test to exhaustion, (3) TLimMAP and (4) TT3km test. There was a tendency of subjects with higher values to TLimMAP performed the TT3km faster (r = -0,71; p = 0,07). It showed positive correlation among TLimMAP and the first time constant of the heart rate at the beginning of exercise (r = 0,95 e p &lt; 0,01), and negative to TLimMAP and the first time constant of the heart rate recovery (r = -0,67 e p = 0,04). The tendency to association among the TLimMAP and performance at the TT3km indicate that the TLimMAP could be utilized in the assessment of cyclists – although with caveats – since there was not significant correlation. Additional investigations to enlighten the relations among TLimMAP, HR kinetics and performance would characterize a proficuous field of research.

Development and Validation of 3 Min Incremental Step-In-Place Test for Predicting Maximal Oxygen Uptake in Home Settings: A Submaximal Exercise Study to Assess Cardiorespiratory Fitness.

The purpose of this research was to develop the 3 min incremental step-in-place (3MISP) test for predicting maximal oxygen uptake (O2max). A total of 205 adults (20–64 years) completed the 3MISP and O2max tests. Using age, gender, body composition (BC) including percent body fat (PBF) or body mass index (BMI), and with or without heart rate (HR) at the beginning of exercise (HR0) or difference between HR at the third minute during the exercise and the first minute post exercise (ΔHR3 − HR4) in the 3MISP test, six O2max prediction models were derived from multiple linear regression. Age (r = −0.239), gender (r = 0.430), BMI (r = −0.191), PBF (r = −0.706), HR0 (r = −0.516), and ΔHR3 − HR4 (r = 0.563) were significantly correlated to O2max. Among the six O2max prediction models, the PBF model∆HR3 − HR4 has the highest accuracy. The simplest models with age, gender, and PBF/BMI explained 54.5% of the O2max in the PBF modelBC and 39.8% of that in the BMI modelBC. The addition of HR0 and ∆HR3 − HR4 increases the variance of O2max explained by the PBF and BMI models∆HR3 − HR4 by 17.98% and 45.23%, respectively, while standard errors of estimate decrease by 10.73% and 15.61%. These data demonstrate that the models established using 3MISP-HR data can enhance the accuracy of O2max prediction.

Serum Interleukin-17 Alterations in Patients With Chronic Kidney Disease Undergoing Eight Weeks of Aerobic Training

Introduction: Regular physical activities may have effect on the course of chronic kidney disease (CKD). Here, we aimed to ascertain the changes of serum interleukin-17 (IL-17) following eight weeks of aerobic training in CKD patients. Methods: The CKD patients referred to Zahedan Edalat Clinic and Ali-Ibn Abi Talib hospital in Zahedan city (Iran) were enrolled. Sixty patients aged between 30 and 50 years old were chosen by a random method and assigned into the control and intervention groups (each group constituted 30 people). In this study, aerobic exercises were performed at 50%–80% of the maximal heart rate. Peripheral blood was obtained one day before the beginning of exercise and one day after the end of the intervention. Serum IL-17 level was quantified using a commercial specific ELISA kit. Results: The mean values of IL-17 in CKD patients before and after 8 weeks of aerobic exercise were 1.67 ± 0.403 pg/mL and 1.58 ± 0.170 pg/mL in the intervention group (P value= 0.039) whereas the mean values of IL-17 in the control group before and after the intervention were 1.31 ± 0.529 pg/mL and 1.35 ± 0.505 pg/mL (P value= 0.794).Conclusion: Eight weeks of aerobic training can significantly reduce serum IL-17, an inflammatory marker, in CKD patients.

The Stress of Competing: Cortisol and Amylase Response to Training and Competition

TeamGym is a popular form of gymnastics, including tumbling (Tu), trampette (Tr) and floor exercises (F) characterized by intensive practice placing high levels of stress on athletes. The aim of the study was to investigate athletes’ stress-related changes during TeamGym training and competition, considering hormonal and enzymatic responses (i.e., salivary cortisol and alpha-amylase). Ten (5 males and 5 females) TeamGym athletes (age: 22–28 y) were tested twice at the same time before training and competition; furthermore, for excluding circadian effect on hormonal and enzymatic responses, they were tested at the same time during a rest day. Alpha-amylase and cortisol were measured 15 min before the beginning of exercise, after each gymnastic equipment performance, and after thirty minutes from the end of the performance. Factorial ANOVA with repeated measures was used to verify differences between training and competition (p < 0.05). Competition elicited higher values of alpha-amylase than training (p ranging from 0.001 to 0.019) and rest (p ranging from 0.001 to 0.019). Cortisol showed no exercise induced increase, and its concentrations were higher prior to training compared to competition. TeamGym responses confirm other sports findings in stating that competition elicits higher stress response than training and suggest that salivary alpha-amylase is a more sensitive marker than cortisol to psychophysiological stress also in gymnastics intermittent performance.

Primary clinical investigation of cardiopulmonary exercise gas exchange in pulmonary hypertension patients with and without right-to-left shunt

Objective: The aim of this study is to determine the changes of gas exchange parameters during ramp incremental cardiopulmonary exercise test (CPET) in patients with pulmonary hypertension (PH) could identify the right to left shunt (R-L Shunt). Methods: We did a retrospective analysis of exercise gas exchange parameters for 73 PH patients and 14 normal subjects as control, in Fuwai Hospital from October 2016 to August 2017, who did CPET with signature on content form. The gas exchange data of CPET were double-blindly independently interpreted by four export-doctors. According to the reading results of CPET, the PH patients were divided into four groups: ① R-L shunt positive group, ② R-L shunt suspicious group, ③R-L shunt negative group, ④late open R-L Shunt positive group. Results: Minute ventilation (VE), ventilatory equivalents for carbon dioxide and oxygen (VE/VCO2, VE/VO2), end-tidal partial pressure of oxygen (PETO2)in R-L shunt positive group were significantly increased ((7.36 ± 2.72) L/min, (1.84± 3.59), (5.02 ±4.34), (3.75±2.64) mmHg) at the beginning of exercise, and were also significantly higher than the control ((4.26 ± 2.59) L/min, (2.22± 2.08), (1.46 ±4.68), (3.96 ± 2.82) mmHg); Partial pressure of carbon dioxide in end expiratory gas (PETCO2) was decreased (-1.63 ±1.66) mmHg, and was significantly lower than control (2.22 ± 2.08) mmHg (P<0.01). Respiratory quotient (RER), carbon dioxide, VE/VCO2, VE/VO2, PETO2 in late open R-L Shunt positive group were suddenly increased ((0.40 ± 0.08), (11.07 ± 5.60),(30.55 ±7.89), (13.72 ±2.21) mmHg) at the end of exercise near the peak, significantly higher than control too ((0.38± 0.12), (5.67± 4.60), (4.54 ± 3.83), (5.51± 4.24) mmHg); PETCO2 was suddenly decreased at the end of the exercise compared to the resting stage (-6.82 ± 1.96) mmHg, and was significantly different from the control (5.67 ±4.60) mmHg. Carbon dioxide ventilatory efficiency, oxygen uptake ventilatory efficiency relative to the peak power (-8.38 ±3.24, -13.14 ± 6.47) at the recovery stage in late open R-L shunt positive group are significantly lower than control (6.22 ±2.87, 16.56± 4.20) (P<0.01). Conclusion: Cardiopulmonary function and ventilation efficiency of patients withpulmonary hypertension are significantly decreased; pulmonary hypertension and right to left shunt in patients not only resting ventilation efficiency is limited more serious; The characteristics of R-L shunt are the sudden increase of PETO2, VE/ VCO2, VE, RER and sudden decrease of PETCO2 and VO2/ VE at the beginning of exercise, and commonly companied with decreased SpO2. For the delay open R-L shunt, these changes occurred near the peak exercise rather than the beginning, and these characteristic changes quickly reversed after stopping exercise.

Effect of pilates exercises on premenstrual syndrome symptoms: a quasi-experimental study

ObjectivesThis study was done to identify the effect of pilates exercises on the symptoms of premenstrual syndrome. DesignA quasi experimental was conducted on university student with premenstrual syndrome. MethodsPopulation of the study included midwifery students with premenstrual syndrome at Istanbul University Faculty of Health Sciences (N = 286) and 50 of them became the sample (25 in experimental group and 25 in control group). Non-probablistic sampling method was used. While the students in experimental group were asked to practice the pilates exercises for three months, the students in control group were told to maintain their routine habits. At the end of the three months, premenstrual syndrome problem of experimental and control group was diagnosed and the effect of pilates on premenstrual syndrome was evaluated. Premenstrual Syndrome symptoms were evaluated through Premenstrual Syndrome Scale (PMSS). The high score received from PMSS shows that the symptoms are intensive. ResultsIt was seen that the students in the experimental and control group were similar in terms of their aspects which were individual, health and could affect premenstrual syndrome (p > 005). A statistical significant difference was not found between total scores and sub-dimension scores of PMSS in experimental and control group (p < 0.05). It was seen that PMSS total score of experimental group was significantly lower than that of control group (p < 0.001). When in-group comparisons were examined, it was identified that PMSS scores of control group did not change at the beginning and end of exercise, but PMSS score of experimental group at the end of exercise was lower than their score received at the beginning of exercise and, the difference was statistically significant to the highest degree (p < 0.001). ConclusionIt was seen that the pilates exercises, which were practiced in this research, decreased the PMS symptoms considerably. In this regard, the pilates exercises have an important role in healing the PMS symptoms.

운동시작단계 노인 테니스 운동참여자의 운동심상과 운동자기효능감, 운동지속의 구조관계 검증

Purpose: This study investigates the structural relationship among exercise image, exercise self-efficacy, and exercise persistence in the elderly tennis participants at the beginning of exercise.BR Method: In order to identify the research objectives, descriptive statistics, exploratory factor analysis, confirmatory factor analysis, reliability analysis, correlation analysis, structural equation model analysis, and bootstrapping analysis were conducted and confirmed using SPSS 22.0 and AMOS 22.0 statistical packages. Based on the derived research results, the following conclusions were drawn. The significant level of hypothesis verification is set-up as α=.05.BR Results: The results of this study are as follows. 1) It was found that the exercise image of the elderly tennis participants at the beginning of exercise had a positive effect on exercise self-efficacy. 2) It was found that the motor image of the elderly tennis participants at the beginning of the exercise had a positive effect on the will to continue the exercise. 3) It was found that exercise self-efficacy of elderly tennis participants at the beginning of exercise had a positive effect on exercise persistence. 4) The partial mediating effect of exercise self-efficacy was verified in the relationship between the exercise image and the willingness to continue the exercise of the elderly tennis participants at the beginning of exercise.BR Conclusion: In summary, at the point when the factors that limit participation in social and environmental exercise due to the Corona pandemic are reinforced, the elderly who observe the quarantine guidelines and continue to participate in tennis exercise are the ones who want to maintain their health and practice successful aging. It is believed that the psychological intervention strategy enabling the continuation of exercise through reinforcing the perception of the exercise mentality of the tennis exercise & a sense of exercise self-efficacy should be applied to the elderly tennis sports field at the beginning of exercise.

Treadmill exercise improves LPS-induced memory impairments via endocannabinoid receptors and cyclooxygenase enzymes

Endocannabinoid system and cyclooxygenase enzymes are implicated in neuroinflammation-induced cognitive impairment. It is believed that non-pharmacological treatments such as physical exercise affect neural systems that control behavioral responses. This research examined the effects of treadmill aerobic exercise on the expression of cannabinoid receptors and cyclooxygenases against LPS-induced cognitive disorders in the hippocampus tissue of rats. For this purpose, rats received intraperitoneal injection of 0.25 mg/kg LPS or saline for 9 continuous days before exercise training. They again received a single i.p. injection with 0.5 mg/kg LPS or saline on days 20 and 41 after the beginning of exercise. The exercise groups were forced to run on a motorized treadmill 5 days per week for 8 weeks. After the last exercise training session, the water maze test was conducted to measure cognitive function. Finally, the hippocampus tissue samples of rats were removed and used to determine the levels of gene expression using the Real-Time PCR method. Data showed that the LPS-treated rats had longer escape distance and longer escape latency to reach the hidden platform and they spent less time than the other groups in the target quadrant, but exercise training improved them in the LPS + Exe (LPS + exercise) group. Exercise increased the expression of CB1 receptor in the Sal + Exe (saline + exercise) group and reduced the expression of CB2 receptor, COX-2 and mPGES-1 in the LPS + Exe group compared to the Sal + LPS group. The findings indicate that treadmill exercise may be beneficial for improvement of cognitive function by modulating the neuroinflammatory processes.

The effect of muscle metaboreflex on the distribution of blood flow in cerebral arteries during isometric exercise.

The present study examined the effect of muscle metaboreflex on blood flow in different cerebral arteries. Eleven healthy participants performed isometric, one-leg knee extension at 30% maximal voluntary contraction for 2min. Activated muscle metaboreflex was isolated for 2min by post-exercise muscle ischemia (PEMI). The contralateral internal carotid (ICA), vertebral (VA), and ipsilateral external carotid arteries (ECA) blood flows were evaluated using Doppler ultrasound. The ICA blood flow increased at the beginning of exercise (P = 0.004) but returned to the baseline level at the end of exercise (P = 0.055). In contrast, the VA blood flow increased and it was maintained until the end of the exercise (P = 0.011), while the ECA blood flow gradually increased throughout the exercise (P = 0.001). These findings indicate that isometric exercise causes a heterogeneous cerebral blood flow response in different cerebral arteries. During PEMI, the conductance of the VA as well as that of the ICA was significantly lower compared with the baseline value (P = 0.020 and P = 0.032, at PEMI90), while the conductance of the ECA was not different from the baseline (P = 0.587), suggesting that the posterior and anterior cerebral vasculature were similarly affected during exercise by activation of muscle metaboreceptors, but not in the non-cerebral artery. Since ECA branches from ICA, the balance in the different influence of muscle metaboreflex on ECA (vasodilation via exercise-induced hypertension) and ICA (vasoconstriction) may contribute to the decrease in ICA blood flow at the end of isometric exercise.

Effects Of Cycling In The Cold On Neuromuscular Activation And Fatigue

PURPOSE: To examine the effects of cold exposure on neuromuscular activation and fatigue during aerobic cycling exercise. METHODS: Five apparently healthy males (24.8 + 2.9 years; 183.1 + 2.2cm; 80.5 + 4.4kg; 11.3 + 2.8%BF; 3.97 + 0.34 L[BULLET OPERATOR]min-1) visited the laboratory on three separate occasions. During the first visit, participants performed a VO2max test on a Velotron cycle ergometer. During the two remaining trials, participants performed two, five-second maximal isometric voluntary contractions (MVICs) of the right leg extensors prior to entering the environmental chamber. In the environmental chamber, volunteers cycled for 60 min at 60% of their VO2max in either a low- (5°C / 45%RH; LT), or moderate-temperature (22°C / 45%; MT), in counterbalanced fashion. Electromyography (EMG) of the vastus lateralis was recorded during the 60-minute exercise protocol during the first two minutes, and during the last two minutes of every 10-minute period (0-2min, 8-10min, 18-20min, 28-30min, 38-40min, 48- 50min, 58-60min). Root mean square (RMS), mean power frequency (MPF) and median power frequency (MEDPF) were then normalized to the MVIC for each time point. Data were analyzed using a within subjects repeated measures ANOVA. RESULTS: No significant differences were observed between conditions (LT and MT) for RMS (F = ; p = 0.591) MPF (F = 0.003; p = 0.959), or MEDPF (F = 1.438; p=0.297). A significant main effect of time was observed for RMS F = 8.187, p<0.001). Specifically, RMS at 8-10Min (26.369 + 3.542%), 18-20Min (24.782 + 3.572%), 38-40Min (25.722 + 3.534%) and 48-50Min (26.070 + 3.451%) were significantly lower than RMS at 58-60Min (27.091 + 3.521%). There was also a significant effect of time for MPF (F = 3.049; p = .023), with a significantly higher MPF at 18-20min (85.694 + 1.467%) and 38-40min (85.942 + 1.408%) compared to 8-10min (83.165 + 1.215%). CONCLUSION: The increase in RMS observed at the end of exercise suggests an increase in neural drive and motor unit activity, suggestive of an increase in motor unit recruitment and fatigue during aerobic cycling exercise at 60% VO2max. Furthermore, MPF significantly increased from the beginning of exercise, suggesting an increase in action potential conduction velocity.

Maternal-fetal acute responses to two moderate-intensity exercise types: a randomized clinical trial

Objective: This study aims to compare maternal and fetal responses during two physical exercise types.&#x0D; Design: A randomized clinical trial compared 120 pregnant women, gestational age of 35-37 weeks, 56 exercising on a stationary bicycle (Group A) and 64 on a treadmill (Group B).&#x0D; Methods: Participants were monitored for three 20-minute phases: resting, exercise and recovery. Fetal heart rate (FHR) and maternal heart rate (MHR) were monitored. Glucose and lactate levels were evaluated at rest and during exercise.&#x0D; Results: After the beginning of exercise, maximum lactate (L) levels were reached at 20 minutes and never exceeded 4 mmol/l. FHR decreased by 22 bpm during exercise in relation to resting values, irrespective of the exercise type (p&lt;0.001). Comparing the exercise types, the incidence of bradycardia after 10’ was 23.2% in Group A and 35.9% in Group B (p&gt;0.05), increasing at 20’ to 32% and 40.6%, respectively, (p&gt;0.05). The FHR decrease during exercise was accompanied by a simultaneous increase in its variability (p&lt;0.001), nevertheless a rapid return to resting values was observed shortly after exercise end. Glucose decreased in both groups irrespective of the exercise type (85 mg/dl at rest; 79 mg/dl during exercise and 81 mg/dl during recovery; p&lt;0.001). There were no hypoglycemia cases.&#x0D; Conclusions: FHR variability increase and the rapid return to resting values after exercise suggests that the FHR fall and the presence of bradycardia during exercise is the fetal physiologic response to blood flow redistribution, with maintenance of fetal well-being.&#x0D; Key-words: Exercise; fetal heart rate; glucose; maternal heart rate; pregnancy&#x0D; Clinical Trial Registration: ClinicalTrials.gov, www.clinicaltrials.gov, NCT01383889.

Effect of ad libitum intake of an electrolyte repository in horses that underwent a polo game

The objective of this study was to assess the effects of an electrolyte and energy repository on the hematologic and biochemical variables of horses after a polo game and compare them to the effects of a commercial electrolyte repository and water. Twelve healthy horses, aged 5 to 10 years, mean body weight 356.25 ± 25.6 kg and in training for polo games, were randomly divided into three groups of four animals each and received one of three treatments. Animals participated in a 7-minute polo game. At the end of the match, they were taken to individual stalls where they received treatments for spontaneous hydration for 6 hours. Treatments were Hydroelectrolytic and Energy Repository (RHE) containing sodium, chloride, potassium, calcium, magnesium, dextrose, maltodextrin and, sucrose; and Commercial Paste (PCO) containing calcium, fructooligosaccharides, glycine, magnesium, potassium, sodium, and ad libitum water. The control group (Water) received water. Blood samples were collected as follows: just before the beginning of exercise (T0), immediately after exercise (T1), 3 hours after the end of exercise (T3), and 6 hours after the end of exercise (T6). The volume of voluntary intake was measured at T3 and T6. Packed cell volume and serum concentrations of sodium, potassium, chloride, calcium, magnesium, phosphorus, creatinine, total protein, plasma glucose, and lactate were measured. Data were submitted to descriptive statistics (mean ± standard deviation), Lilliefors and Cochran &amp; Bartlett tests, analysis of variance (ANOVA), and Tukey or Duncan tests at a 5% significance level. The net volume ingested by the RHE group was higher than the PCO and control groups. In all groups, a reduction in chloride concentration and increases in packed cell volume, protein, creatinine, glucose, and lactate concentrations were observed in T1. These variables returned to the values found at T0 throughout the rehydration phase (T3 and T6). It is concluded that the ingestion of the hydroelectrolytic energy repository does not cause alteration in the biochemical profile of the animals.

Effect of the timing of ice slurry ingestion for precooling on endurance exercise capacity in a warm environment

It has been demonstrated that precooling with ice slurry ingestion enhances endurance exercise capacity in the heat. However, no studies have yet evaluated the optimal timing of ice slurry ingestion for precooling. This study aimed to investigate the effects of varying the timing of ice slurry ingestion for precooling on endurance exercise capacity in a warm environment. Ten active male participants completed 3 experimental cycling trials to exhaustion at 55% peak power output (PPO) after 15min of warm-up at 30% PPO at 30°C and 80% relative humidity. Three experimental conditions were set: no ice slurry ingestion (CON), pre-warm-up ice slurry ingestion (−1°C; 7.5gkg−1) (PRE), and post-warm-up ice slurry ingestion (POST). Rectal and mean skin temperatures at the beginning of exercise in the POST condition (37.1±0.2°C, 33.8±0.9°C, respectively) were lower than those in the CON (37.5±0.3°C; P<0.001, 34.8±0.8°C; P<0.01, respectively) and PRE (37.4±0.2°C; P<0.01, 34.6±0.7°C; P<0.01, respectively) conditions. These reductions increased heat storage capacity and resulted in improved exercise capacity in the POST condition (60.2±8.7min) compared to that in the CON (52.0±11.9min; effect size [ES]=0.78) and PRE (56.9±10.4min; ES=0.34) conditions. Ice slurry ingestion after warm-up effectively reduced both rectal and skin temperatures and increased cycling time to exhaustion in a warm environment. Timing ice slurry ingestion to occur after warm-up may be effective for precooling in a warm environment.

Influence of warm-up duration and recovery interval prior to exercise on anaerobic performance.

The purpose of the study was to determine the impact of different active warm-up (AWU) durations and the rest interval separating it from exercise on anaerobic performance. Eleven male physical education students (22.6 ± 2.52 years; 179.2 ± 4.3 cm; 82.5 ± 9.7 kg; mean ± SD) participated in a cross-over randomized study, and they all underwent the Wingate test after three AWU durations: 5 min (AWU5), 15 min (AWU15) and 20 min (AWU20), with recovery (WREC) or without a recovery interval (NREC) separating the AWU and anaerobic exercise performance. All the AWUs consisted of pedalling at a constant pace of 60 rpm at 50% of the maximal aerobic power. The rest interval between the end of warm-up and the beginning of exercise was set at 5 min. During the Wingate test, peak power (PP), mean power (MP) and the fatigue index (FI) were recorded and analysed. Oral temperature was recorded at rest and at the end of the warm-up. Likewise, rest, post-warm-up and post-Wingate heart rate (HR) and rating of perceived exertion (RPE) were recorded during each session. The ANOVA showed a significant effect of recovery interval, warm-up duration and measurement point on RPE scores (P<0.001). Although the effect of AWU duration on MP and PP was significant (P<0.05), the effect of the recovery interval on both parameters was not significant (P>0.05). Moreover, the analyses showed a significant interaction between recovery interval and AWU duration (P<0.001 and P<0.05 for MP and PP respectively). The AWU15 duration improves the MP and PP when associated with a recovery interval prior to exercise of 5 min. However, the AWU5 duration allows better improvement of power output when the exercise is applied immediately after the warm-up. Consequently, physically active males, as well as educators and researchers interested in anaerobic exercise, must take into account the duration of warm-up and the following recovery interval when practising or assessing activities requiring powerful lower limb muscle contractions.

The Wingate anaerobic test cannot be used for the evaluation of growth hormone secretion in children with short stature

PurposeTo assess the growth hormone (GH) response to the Wingate anaerobic test (WAnT) among children with short stature and suspected GH deficiency. We hypothesized that the GH response to the WAnT would be similar to the GH response to a commonly used pharmacologic provocation test. MethodsTen children (6 males and 4 females, age range 9.0–14.9 years) participated in the study. Each participant performed 2 tests: a standard all-out WAnT, cycling for 30 s against constant resistance, and a standardized pharmacologic test (clonidine or glucagon). Blood samples for GH were collected before and 10, 30, 45, and 60 min after the beginning of exercise. In addition, we collected pre- and post-exercise blood lactate levels. ResultsThere was a significant increase in GH levels after the WAnT, yet in 9 of 10 participants, this increase was below the threshold for GH sufficiency. Peak GH after the WAnT was significantly lower compared to the pharmacologic GH provocation tests (with 9 of 10 demonstrating GH-sufficient response). ConclusionThe traditional WAnT cannot be used as a GH provocation test. Further research is needed to develop anaerobic exercise protocols sufficient to promote GH secretion.

Delayed Anaerobic Threshold in Heart Failure Patients With Atrial Fibrillation.

To assess whether atrial fibrillation (AF) in heart failure (HF) affects oxygen uptake at anaerobic threshold ((Equation is included in full-text article.)O2 AT) and heart rate (HR) kinetics. A total of 15 patients with HF and AF and 18 with HF and sinus rhythm (SR) performed a maximal incremental and 2 constant workload cycle ergometer cardiopulmonary exercise tests (below and above AT, at 25% and 75% of maximal workload, respectively). At constant workload tests, kinetics of (Equation is included in full-text article.)O2 and HR were assessed by calculating time constant (τ). HF patients with AF showed a similar peak (Equation is included in full-text article.)O2 to those with SR (16.7 ± 4.5 mL/kg/min vs 16.6 ± 3.9 mL/kg/min). However, (Equation is included in full-text article.)O2 AT (11.3 ± 2.9 mL/kg/min vs 9.3 ± 2.8 mL/kg/min; P < .05), peak HR (149 ± 18.8 bpm vs 116.4 ± 20.4 bpm; P < .001), HR AT (125.3 ± 19.1 bpm vs 90.3 ± 15.5 bpm; P < .001), and HR increase during exercise were greater in HF patients with AF. Finally, τHR and τ(Equation is included in full-text article.)O2 below and above AT were not significantly different. In HF patients with AF, despite a similar peak (Equation is included in full-text article.)O2 compared with patients with HF and SR, (Equation is included in full-text article.)O2 AT is higher because of a higher HR and a greater HR increase during exercise. One postulated mechanism would be a greater cardiac output increase at the beginning of exercise in HF patients with AF. The delayed AT generates uncertainty about the meaning of a (Equation is included in full-text article.)O2 value at AT in HF patients with AF, because a higher AT is usually associated with better performance and a better prognosis.

Central command generated prior to arbitrary motor execution induces muscle vasodilatation at the beginning of dynamic exercise.

The purpose of this study was to examine the role of central command, generated prior to arbitrary motor execution, in cardiovascular and muscle blood flow regulation during exercise. Thirty two subjects performed 30 s of two-legged cycling or 1 min of one-legged cycling (66 ± 4% and 35% of the maximal exercise intensity, respectively), which was started arbitrarily or abruptly by a verbal cue (arbitrary vs. cued start). We measured the cardiovascular variables during both exercises and the relative changes in oxygenated-hemoglobin concentration (Oxy-Hb) of noncontracting vastus lateralis muscles as index of tissue blood flow and femoral blood flow to nonexercising leg during one-legged cycling. Two-legged cycling with arbitrary start caused a decrease in total peripheral resistance (TPR), which was smaller during the exercise with cued start. The greater reduction of TPR with arbitrary start was also recognized at the beginning of one-legged cycling. Oxy-Hb of noncontracting muscle increased by 3.6 ± 1% (P < 0.05) during one-legged cycling with arbitrary start, whereas such increase in Oxy-Hb was absent with cued start. The increases in femoral blood flow and vascular conductance of nonexercising leg were evident (P < 0.05) at 10 s from the onset of one-legged cycling with arbitrary start, whereas those were smaller or absent with cued start. It is likely that when voluntary exercise is started arbitrarily, central command is generated prior to motor execution and then contributes to muscle vasodilatation at the beginning of exercise. Such centrally induced muscle vasodilatation may be weakened and/or masked in the case of exercise with cued start.

Regional Skin Temperature Response to Moderate Aerobic Exercise Measured by Infrared Thermography.

Background:Infrared thermography (IRT) does not require contact with the skin, and it is a convenient, reliable and non-invasive technique that can be used for monitoring the skin temperature (TSK).Objectives:The aim of this study was to monitor the variations in the regional TSK during exercise on 28 regions of interest (ROIs) (forehead, face, chest, abdomen, back, lumbar, anterior and posterior neck, and posterior and anterior views of the right and left hands, forearms, upper arms, thighs, and legs) with IRT.Patients and Methods:12 physically active young males were monitored with IRT during the following three phases: a) 30 minutes before exercise b) while performing one hour of moderate intensity exercise on a treadmill at 60% of the VO2max, and c) 60 minutes after exercise.Results:During pre-exercise, all TSK reached a steady-state (P ≤ 0.05), which ensured adequate thermal stabilisation. At the beginning of exercise, there was a significant reduction in the TSK in most ROIs after 10 minutes of activity, except for the lower limbs (legs and thighs). After one hour of recovery, in the anterior view of the hands and thighs and in the posterior view of the legs, there were significant increases in the TSK compared to pre-exercise.Conclusions:There were significant distinctions in the skin temperature distribution during exercise according to the activity of the area under consideration during exercise, which may be important in the development of physiological models and heat flux analyses for different purposes.