The relationship between heart rate and energy expenditure in Alpine, Angora, Boer and Spanish goat wethers consuming different quality diets at level of intake near maintenance or fasting

Six Alpine (AL; 38.4 ± 3.0 kg), Angora (AN; 23.1 ± 2.7 kg), Boer (BO; 40.8 ± 4.5 kg) and Spanish (SP; 33.6 ± 2.2 kg) wethers (1.5 yr of age) were used to determine the effects of time of the day and potential interactions between time, genotype and diet quality on energy expenditure (EE), heart rate (HR) and EE:HR when fed near maintenance and fasting. The experiment consisted of four simultaneous crossovers, with 21 d for adaptation before measures. Diets were 60% concentrate (CON: 15% CP) and ground alfalfa hay (FOR: 23% CP), offered in two meals at 8:00 and 16:00 h. Energy expenditure was determined from O₂ consumption and production of CO₂ and CH₄ over 2-day periods in fed and fasting states (total 4-day fasting period). Fasting EE was higher during the day than night, with values generally highest at 16:00–17:00 h. Animal within breed affected EE, HR and EE:HR (P < 0.05). The diurnal pattern in EE varied with diet (P < 0.05), although total daily EE was not different between diets. Before the morning meal, there were a number of hours during which EE was greater for CON than for FOR. However, at both meals the rise in EE was considerably greater for FOR versus CON, lasting for 3–4 h. The same general pattern in HR was observed, although the period of time when there was a dietary difference after the afternoon meal was shorter. For both fed and fasted goats, EE:HR differed among hours of the day (P < 0.05). EE:HR tended (P < 0.09) to differ between diets (5.99 and 6.21 for CON and FOR, respectively) and to be affected (P < 0.09) by an interaction between breed and diet (AL: 5.84 and 6.38; AN: 5.91 and 5.73; BO: 6.05 and 6.58; and SP: 6.17 and 6.15 kJ/(kg BW^0.75 × day):heart beats/min) for CON and FOR, respectively. In conclusion, for use of HR to predict EE by goats, it appears desirable to determine the ratio of EE:HR with a diet similar to that consumed during prediction and over an extended period of time.     

Human energy expenditure when walking on a moving platform

The assumption that working on board ship is more strenuous than comparable work ashore was investigated in this study. Various physiological parameters (V˙O₂, V˙CO₂, V˙ _E and HR) have been measured to determine the energy expenditure of subjects walking slowly on a moving platform (ship motion simulator). Twelve subjects (eight men and four women) walked either freely on the floor or on a treadmill at a speed of 1 m · s⁻¹. Platform motion was either in a heave, pitch or roll mode. These three conditions were compared with a control condition in which the platform remained stationary. The results showed that during pitch and roll movements of the platform, the energy expenditure for the same walking task was about 30% higher than under the stationary control condition (3.6 J · kg⁻¹ · m⁻¹ vs 2.5 J · kg⁻¹ · m⁻¹, P < 0.05) for both walking on a treadmill and free walking. The heart rate data supported the higher energy expenditure results with an elevation of the heart rate (112 beats · min⁻¹ vs 103 beats · min⁻¹, P < 0.05). The heave condition did not differ significantly from the stationary control condition. Pitch and roll were not significantly different from each other. During all experimental conditions free walking resulted in a higher energy cost of walking than treadmill walking (3.5 J · kg⁻¹ · m⁻¹ vs 2.7 J · kg⁻¹ · m⁻¹, P < 0.05) at the same average speed. The results of this experiment were interpreted as indicating that the muscular effort, needed for maintaining balance when walking on a pitching or rolling platform, resulted in a significantly higher work load than similar walking on a stable or a heaving floor, independent of the mode of walking. These results explain in part the increased fatigue observed when a task is performed on a moving platform. Accepted: 3 October 1997     

12周高强度间歇训练对大学生健康体适能、能量消耗和心率的影响

目的:探讨高强度间隙训练(HIIT)对大学生健康体适能、能量消耗和心率的影响。方法:以18～19岁男性大学生108人为研究对象,平均配对分为2组,一组为对照组,参加正常体育课;一组为试验组,在正常体育课上进行1次HIIT,课外进行2次HIIT,包含原地高抬腿、开合跳、弓步跳、立卧撑、原地深蹲、平板支撑、俄罗斯转体、俯卧背肌8个动作,每次8～10 min,共持续12周,对试验前后两组大学生的身体成分、能量消耗、肌肉力量、心肺适能和心率进行了测试。结果:与对照组相比,试验组学生心肺适能、肌肉适能、能量消耗均有所提高,其中立定跳远、静息能量消耗、总能量消耗、最大心率以及安静时心率显著升高(P＜ 0.05)。与试验前比较,试验组立定跳远、肺活量和中长跑成绩显著高于试验前(P＜0.05);试验组身体成分改善,BMI下降;静息心率降低。结论:HIIT是一种高效、安全的运动方式,花费时间少,能有效增加能量消耗,提高肌肉和心肺适能,增加最大心率和安静时心率。     

Comparison of energy expenditure and substrate oxidation between walking and running in men and women

[Purpose]The present study compared energy metabolism between walking and running at equivalent speeds during two incremental exercise tests.[Methods]Thirty four university students (18 males, 16 females) were recruited. Each participant completed two trials, consisting of walking (Walk) and running (Run) trials on different days, with 2-3 days apart. Exercise on a treadmill was started from initial stage of 3 min (3.0 k/m in Walk trial, 5.0 km/h in Run trial), and the speed for walking and running was progressively every minute by 0.5 km/h. The changes in metabolic variables, heart rate (HR), and rating of perceived exertion (RPE) during exercise were compared between the trials.[Results]Energy expenditure (EE) increased with speed in each trial. However, the Walk trial had a significantly higher EE than the Run trial at speeds exceeding 92 ± 2 % of the maximal walking speed (MWS, p < 0.01). Similarly, carbohydrate (CHO) oxidation was significantly higher in the Walk trial than in the Run trial at above 92 ± 2 %MWS in males (p < 0.001) and above 93 ± 1 %MWS in females (p < 0.05).[Conclusion]These findings suggest that EE and CHO oxidation during walking increase non-linearly with speed, and walking at a fast speed causes greater metabolic responses than running at the equivalent speed in young participants.     

Energy expenditure and cardiorespiratory responses at the transition between walking and running

We investigated whether the spontaneous transition between walking and running during moving with increasing speed corresponds to the speed at which walking becomes less economical than running. Seven active male subjects [mean age, 23.7 (SEM 0.7) years, mean maximal oxygen uptake ( ), 57.5 (SEM 3.3) ml·kg ^–1·min ^–1, mean ventilatory threshold (VTh), 37.5 (SEM 3) ml·kg ^–1 ·min ^–1] participated in this study. Each subject performed four exercise tests separated by 1-week intervals: test 1, and VTh were determined; test 2, the speed at which the transition between walking and running spontaneously occurs (ST) during increasing speed (increases of 0.5 km·h ^–1 every 4 min from 5 km·h ^–1) was determined; test 3, the subjects were constrained to walk for 4 min at ST, at ST ± 0.5 km·h ^–1 and at ST ± 1 km·h ^–1; and test 4, the subjects were constrained to run for 4 min at ST, at ST±0.5 km·-h ^–1 and at ST±1 km·h ^–1. During exercise, oxygen uptake ( ), heart rate (HR), ventilation ( ), ventilatory equivalents for oxygen and carbon dioxide (% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmOvayaaca% WaaSbaaSqaaiaabweaaeqaaOGaai4laiqadAfagaGaamaaBaaaleaa% caqGYaaabeaakiaacYcacaqGGaGaaeiiaiqadAfagaGaamaaBaaale% aacaqGfbaabeaakiaac+caceWGwbGbaiaacaqGdbGaae4tamaaBaaa% leaacaaIYaaabeaaaaa!4240!\[\dot V_{\text{E}} /\dot V_{\text{2}} ,{\text{ }}\dot V_{\text{E}} /\dot V{\text{CO}}_2 \]), respiratory exchange ratio (R), stride length (SL), and stride frequency (SF) were measured. The results showed that: ST occurred at 2.16 (SEM 0.04) m·s ^–1; , HR and speed at ST were significantly lower than the values measured at VTh (P< 0.001, P< 0.001 and P< 0.05, respectively); changed significantly with speed (P< 0.001) but was greater during running than walking below ST (ST minus 1 km·h ^–1, P< 0.001; ST minus 0.5 km·h ^–1, P< 0.05) with the converse above ST (ST.plus 1 km·h ^–1, P<0.05), whereas at ST the values of were very close [23.9 (SEM 1.1) vs 23.7 (SEM 0.8) ml·kg ^–1 · min ^–1 not significant, respectively, for walking and running]; SL was significantly greater during walking than running (P<0.001) and SF lower (P<0.001); and HR and were significantly greater during running than walking below ST (ST minus 1 km·h ^–1, P<0.01; ST minus 0.5 km·h ^–1, P{<0.05) with the converse above ST (ST plus 1 km·h ^–1, P·< 0.05), whereas no difference appeared for and R between the two types of locomotion. We concluded from this study that ST corresponded to the speed at which the energy expenditure of running became lower than the energy expenditure of walking but that the mechanism of the link needed further investigation.     

Comparison of heart rate monitoring combined with indirect calorimetry and the doubly labelled water (2H218O) method for the measurement of energy expenditure in children

The aim of the present study was to compare data on 24-h energy expenditure (EE24h) in nine boys and ten girls (mean age 9.3 and 8.1 years, respectively) by heart rates (fc) combined with energy expenditure obtained from a 1-day stay in an indirect calorimeter (EEcal) and a 2-week period of normal living using the doubly labelled water method (EEdlw). Individual calibration curves were derived from fc and oxygen uptake measured during sleep (in the calorimeter), standing and walking on a treadmill. An estimation of energy expenditure based on 24-h fc monitoring (EEfc) was made during the stay in the calorimeter and on a normal school-day. Mean results showed an overestimation in EEfc compared to EEcal and EEdlw of 10.4% and 12.3% respectively, varying from 6.3% to 16.2%. These results confirmed earlier observations in adults that for a group the fc method overestimates EE24h by about 10%.     

Oxygen uptake,heart rate,perceived exertion,and integrated electromyogram of the lower and upper extremities during level and Nordic walking on a treadmill

The purpose of this study was to characterize responses in oxygen uptake ( V·O2), heart rate (HR), perceived exertion (OMNI scale) and integrated electromyogram (iEMG) readings during incremental Nordic walking (NW) and level walking (LW) on a treadmill. Ten healthy adults (four men, six women), who regularly engaged in physical activity in their daily lives, were enrolled in the study. All subjects were familiar with NW. Each subject began walking at 60 m/min for 3 minutes, with incremental increases of 10 m/min every 2 minutes up to 120 m/min V·O2 , V·E and HR were measured every 30 seconds, and the OMNI scale was used during the final 15 seconds of each exercise. EMG readings were recorded from the triceps brachii, vastus lateralis, biceps femoris, gastrocnemius, and tibialis anterior muscles. V·O2 was significantly higher during NW than during LW, with the exception of the speed of 70 m/min (P < 0.01). V·E and HR were higher during NW than LW at all walking speeds (P < 0.05 to 0.001). OMNI scale of the upper extremities was significantly higher during NW than during LW at all speeds (P < 0.05). Furthermore, the iEMG reading for the VL was lower during NW than during LW at all walking speeds, while the iEMG reading for the BF and GA muscles were significantly lower during NW than LW at some speeds. These data suggest that the use of poles in NW attenuates muscle activity in the lower extremities during the stance and push-off phases, and decreases that of the lower extremities and increase energy expenditure of the upper body and respiratory system at certain walking speeds.     

Acceleration versus heart rate for estimating energy expenditure and speed during locomotion in animals: tests with an easy model species, Homo sapiens

An important element in the measurement of energy budgets of free-living animals is the estimation of energy costs during locomotion. Using humans as a particularly tractable model species, we conducted treadmill experiments to test the validity of tri-axial accelerometry loggers, designed for use with animals in the field, to estimate rate of oxygen consumption (VO2: an indirect measure of metabolic rate) and speed during locomotion. The predictive power of overall dynamic body acceleration (ODBA) obtained from loggers attached to different parts of the body was compared to that of heart rate (fH). When subject identity was included in the statistical analysis, ODBA was a good, though slightly poorer, predictor of VO2 and speed during locomotion on the flat (mean of two-part regressions: R2=0.91 and 0.91, from a logger placed on the neck) and VO2 during gradient walking (single regression: R2=0.77 from a logger placed on the upper back) than was fH (R2=0.96, 0.94, 0.86, respectively). For locomotion on the flat, ODBA was still a good predictor when subject identity was replaced by subject mass and height (morphometrics typically obtainable from animals in the field; R2=0.92 and 0.89) and a slightly better overall predictor than fH (R2=0.92 and 0.85). For gradient walking, ODBA predicted VO2 more accurately than before (R2=0.83) and considerably better than did fH (R2=0.77). ODBA and fH combined were the most powerful predictor of VO2 and speed during locomotion. However, ODBA alone appears to be a good predictor and suitable for use in the field in particular, given that accelerometry traces also provide information on the timing, frequency and duration of locomotion events, and also the gait being used.     

Effect of trunk load on the energy expenditure of treadmill walking and ergometer cycling

Data concerning the effect of trunk loads on the energy expenditure of various activities are scanty and partly conflicting. The energy expenditure of walking (4.5 km hr-1, 1.5% inclination) and ergometer cycling (60 watt, 60 rpm) was measured in 23 apparently healthy subjects with and without a trunk load of 10% of the body weight. For walking, the increment in energy expenditure per kg of load was 2.55 +/- 0.25 watt, while the increment per kg of body weight was 4.01 +/- 0.45 watt. For ergometer cycling, the increment per kg of load was 1.12 +/- 0.64 while that per kg of body weight was 2.73 +/- 0.56 watt. Prediction of energy expenditure for trunk loads has previously been made on the basis of the relation between energy expenditure and body weight. Our data show that this may lead to considerable overestimation.     

The time and energy expenditure of indigenous women horticulturalists in the Northwest Amazon

The energy cost of subsistence activities and the daily time and energy budgets of Tatuyo women were assessed as part of a village energy flow study. The Tatuyo are swidden horticulturalists relying on bitter manioc (Manihot esculenta) as a staple crop. Except for the actual felling of new gardens, women are responsible for most of the horticultural work and food preparation. Time budgets were assessed using 24-hour activity diaries. Rates of energy expenditure in typical activities were measured by indirect calorimetry using a Max-Planck respirometer. Daily energy expenditure was calculated using these rates in conjunction with the activity diaries. Rates of energy expenditure in standard activities were moderate and broadly comparable to published values for other populations living in tropical environments. The mean daily energy expenditure was 2,133 kcal (8.9 MJ). This value is similar to that reported for other subsistence horticulturalists and close to the FAO recommendation for energy intake for moderately active individuals.     

The effect of uphill and downhill walking on gait parameters: A self-paced treadmill study

It has been shown that gait parameters vary systematically with the slope of the surface when walking uphill (UH) or downhill (DH) (Andriacchi et al., 1977; Crowe et al., 1996; Kawamura et al., 1991; Kirtley et al., 1985; McIntosh et al., 2006; Sun et al., 1996). However, gait trials performed on inclined surfaces have been subject to certain technical limitations including using fixed speed treadmills (TMs) or, alternatively, sampling only a few gait cycles on inclined ramps. Further, prior work has not analyzed upper body kinematics. This study aims to investigate effects of slope on gait parameters using a self-paced TM (SPTM) which facilitates more natural walking, including measuring upper body kinematics and gait coordination parameters.Gait of 11 young healthy participants was sampled during walking in steady state speed. Measurements were made at slopes of +10°, 0° and −10°. Force plates and a motion capture system were used to reconstruct twenty spatiotemporal gait parameters. For validation, previously described parameters were compared with the literature, and novel parameters measuring upper body kinematics and bilateral gait coordination were also analyzed.Results showed that most lower and upper body gait parameters were affected by walking slope angle. Specifically, UH walking had a higher impact on gait kinematics than DH walking. However, gait coordination parameters were not affected by walking slope, suggesting that gait asymmetry, left-right coordination and gait variability are robust characteristics of walking. The findings of the study are discussed in reference to a potential combined effect of slope and gait speed. Follow-up studies are needed to explore the relative effects of each of these factors.     

Combined effects of molt and chronic stress on heart rate, heart rate variability, and glucocorticoid physiology in European Starlings

Molt is an important life-history stage in avian species, but little is known about the effects of chronic stress during this period. Three weeks after the onset of molt, captive European starlings (Sturnus vulgaris) were exposed to 18 days of chronic stress, induced with four 30-minute randomized stressors presented daily. Birds showed no chronic-stress-induced changes in heart rate or heart rate variability when measured either during the middle of the day or at night. These data suggest that chronic stress did not alter the balance between sympathetic and parasympathetic nervous system regulation of cardiovascular function, which contrasts with data from an earlier study indicating that chronic stress profoundly alters cardiovascular function in non-molting starlings. Additionally, there was a significant increase in restraint-induced corticosterone secretion the first week of chronic stress that subsequently returned to pre-chronic-stress levels by the second week of exposure. The attenuated corticosterone response again contrasts with data from non-molting starlings that showed significant decreases in corticosterone responses. Consequently, the resistance to cardiovascular and corticosterone changes indicates that the physiological changes induced by chronic stress are greatly attenuated in molting birds. Overall, the data suggest that molt requires a degree of physiological stability that must be protected, so that if a bird is exposed to chronic stress during this life-history stage, molt takes priority.     

Effects of gradient and age on energy expenditure and fat metabolism during aerobic exercise at equal intensity in women

[Purpose]This study aimed to investigate the effects of gradient and age on energy expenditure and fat metabolism during aerobic exercise at equal intensity in women.[Methods] Thirty women in their twenties (n=15) and fifties (n=15) were enrolled. All subjects performed aerobic exercise on a treadmill for 10 min at 0% and 6% gradient repeatedly to elicit 50%, 60%, and 70% VO₂max.[Results]Energy expenditure and fat oxidation were higher during aerobic exercise at 6% of the gradient than at 0%, and there was no significant difference in carbohydrate oxidation in any age group.[Conclusion]Aerobic exercise at a 6% gradient was more favorable for fat oxidation than a 0% gradient in all age groups. In particular, in the case of women in their fifties, walking on a gradient of 6%, which is favorable for increasing fat oxidation, was more effective than walking on flat ground for preventing and reducing obesity. However, to examine the difference in fat oxidation among exercise intensities more accurately, exercise performed for longer than 30 min is required. Follow-up studies are required to investigate the effect of various gradients on physiological and metabolic characteristics when carrying out aerobic exercises for more than 30 min.     

The energy cost of common tasks in rural Nepal: levels of energy expenditure compatible with sustained physical activity

Three hundred and six measurements of energy expenditure by indirect calorimetry of sitting at rest and self-paced activity were made on 41 men, 48 women and 6 adolescents in a mountain village of Nepal. Except for walking and carrying uphill, measured activities fell within the range of values for light to moderate effort, despite appearing physically demanding. Villagers tended to reduce travel speed when carrying heavy loads (54-102% of body mass on various inclines), averaging a moderate level of energy expenditure which could be sustained throughout the day. Such moderately demanding work was also assumed by pregnant, lactating women and young adolescents. Pregnant women worked more slowly at some tasks, but did not differentiate themselves from their non-pregnant, non-lactating counterparts for travel on the mountain side.     

Response of heart rate and cloacal ventilation in the bimodally respiring freshwater turtle, Rheodytes leukops, to experimental changes in aquatic PO2

Changes in heart rate (f _H) and cloacal ventilation frequency (f _C) were investigated in the Fitzroy turtle, Rheodytes leukops, under normoxic (17.85 kPa) and hypoxic (3.79 kPa) conditions at 25°C. Given R. leukops’ high reliance on aquatic respiration via the cloacal bursae, the objective of this study was to examine the effect of varying aquatic PO₂ levels upon the expression of a bradycardia in a freely diving, bimodally respiring turtle. In normoxia, mean diving f _H and f _C for R. leukops remained constant with increasing submergence length, indicating that a bradycardia failed to develop during extended dives of up to 3 days. Alternatively, exposure to aquatic hypoxia resulted in the expression of a bradycardia as recorded by a decreasing mean diving f _H with increasing dive duration. The observed bradycardia is attributed to a hypoxic-induced metabolic depression, possibly facilitated by a concurrent decrease in f _C. Results suggest that R. leukops alters its strategy from aquatic O₂ extraction via cloacal respiration in normoxia to O₂ conservation when exposed to aquatic hypoxia for the purpose of extending dive duration. Upon surfacing, a significant tachycardia was observed for R. leukops regardless of aquatic PO₂, presumably functioning to rapidly equilibrate blood and tissue gas tensions with alveolar gas to reduce surfacing duration.     

Go but not Gi2 or Gi3 is required for muscarinic regulation of heart rate and heart rate variability in mice

Muscarinic receptor-mediated cardiac parasympathetic activity is essential for regulating heart rate and heart rate variability (HRV). It has not been clear which G(i)/G(o) protein is responsible for these effects. We addressed this question using knockout mice that lack G protein alpha(i2), alpha(i3), or alpha(o) specifically. Unlike previously reported, our alpha(o)-null mice had significantly more survivors with normal life span. Isolated hearts from alpha(o)-null mice demonstrated much less sensitivity to the negative chronotropic effects of the muscarinic agonist carbachol to lower heart rate at baseline and a more profound effect under the stimulation of the beta-adrenergic agonist isoproterenol. In the presence of parasympathetic activation indirectly produced by methoxamine, an alpha(1)-adrenergic agonist, alpha(o)-null mice showed markedly decreased HRV compared with wild-type control mice. These differences in heart rate and HRV were not observed in alpha(i2)-null or alpha(i3)-null mice. Our findings establish an essential role for alpha(o) G protein in the anti-adrenergic effect of carbachol on heart rate regulation.     

Dorsal medullary oxytocin, vasopressin, oxytocin antagonist, and TRH effects on gastric acid secretion and heart rate

Injections of oxytocin and TRH (11 picomoles), centered on the dorsal motor nucleus of the vagus, substantially increased gastric acid secretion. Additionally, oxytocin, but not TRH, simultaneously produced a consistent reduction in heart rate. Vasopressin injected into the same locus, at doses of 11 and 110 picomoles, had no effect on either function. Both the gastric and cardiac effects of oxytocin were eliminated by the central injections of oxytocin antagonist dEt₂Tyr(Et)Orn⁸Vasotocin (ETOV; 6 picomoles) or peripheral administration of atropine (300 μg/kg, IP). Application of oxytocin or TRH to the area postrema, at double the dosage (22 picomoles) yielded no consistent effects on either gastric secretion or heart rate. These findings indicate that oxytocin in the dorsal motor nucleus of the vagus may act as a regulator of vagally-mediated gastric and cardiovascular functions while TRH effects, in this medullary area, seem limited to the regulation of gastric function.     

Effect of energy drink dose on exercise capacity,heart rate recovery and heart rate variability after high-intensity exercise

[Purpose]

The purpose of this research was to investigate the effects of exercise capacity, heart rate recovery and heart rate variability after high-intensity exercise on caffeine concentration of energy drink.

[Methods]

The volunteers for this study were 15 male university student. 15 subjects were taken basic physical examinations such as height, weight and BMI before the experiment. Primary tests were examined of VO₂max per weight of each subjects by graded exercise test using Bruce protocol. Each of five subject was divided 3 groups (CON, ECGⅠ, ECGⅡ) by matched method based on weight and VO₂max per weight what gained of primary test for minimize the differences of exercise capacity and ingestion of each groups. For the secondary tests, the groups of subjects were taken their materials before and after exercise as a blind test. After the ingestion, subjects were experimented on exercise test of VO₂max 80% by treadmill until the all-out. Heart rate was measured by 1minute interval, and respiratory variables were analyzed VO2, VE, VT, RR and so on by automatic respiratory analyzer. And exercise exhaustion time was determined by stopwatch. Moreover, HRV was measured after exercise and recovery 3 min.

[Results]

Among the intake groups, ECGⅡ was showed the longest of exercise exhaustion time more than CON group (p = .05). Result of heart rate during exercise according to intake groups, there was significant differences of each time (p < .001), however, not significant differences of each groups and group verse time (p > .05). Result of RPE during exercise according to intake groups, there was significant differences of each time (p < .001), however, not significant differences of each groups and group verse time (p > .05).

[Conclusion]

In conclusion, EDGⅡ showed the significant increase of exercise exhaustion time more than CON group (p=.05) and not significant differences in HR, RPE, RER, HRV, HRR, blood pressure (p > .05). Therefore, 2.5 mg/kg^-1 ingestion of energy drink might be positive effect to increase exercise performance capacity without side-effect in cardiovascular disease.     

Cortisol and progestin release, heart rate and heart rate variability in the pregnant and postpartum mare, fetus and newborn foal

The mechanisms leading to parturition in the horse in many aspects differ from those in other species. Pregnancy is maintained not by progesterone but by 5α-pregnanes and the progestin precursor pregnenolone originates from the fetus. As parturition approaches, the fetal adrenal switches from pregnenolone to cortisol synthesis but it is not known whether cortisol crosses the placenta. We hypothesized that in parallel to fetal cortisol release, cortisol in the maternal circulation increases before foaling and this increase can be determined in both saliva and plasma. In addition, maternal, fetal and neonatal heart rate and heart rate variability were measured. In 25 pregnant mares, saliva for cortisol analysis was collected 4 times daily from 15 days before to 5 days after foaling. In 13 mares, in addition, fetomaternal electrocardiogram (ECG) recordings were made and blood samples for progestin and cortisol analysis were collected once daily. Heart rate (HR) was recorded until 5 days after foaling. The heart rate variability (HRV) variables standard deviation of the beat-to-beat (RR) interval (SDRR) and root mean square of successive RR differences (RMSSD) were calculated. From Days 15 to 4 before parturition, progestin concentration increased (peak 267 ± 42 ng/mL) and decreased thereafter (P < 0.05, day of foaling 113 ± 18 ng/mL). A prepartum increase in maternal cortisol concentrations was evident in blood (P < 0.05) and saliva (P < 0.05) and paralleled the decrease in progestin concentrations. In mares, HR remained constant during the last days of pregnancy but decreased within one day after parturition (P < 0.05) while maternal HRV did not change. In the fetus and neonate, HR increased from before to after birth (P < 0.05) indicating increasing demands on the cardiovascular system with adaptation to extrauterine life.     

Partitioning of late gestation energy expenditure in ewes using indirect calorimetry and a linear regression approach

Abstract

Late gestation energy expenditure (EE_gest) originates from energy expenditure (EE) of development of conceptus (EE_conceptus) and EE of homeorhetic adaptation of metabolism (EE_homeorhetic). Even though EE_gest is relatively easy to quantify, its partitioning is problematic. In the present study metabolizable energy (ME) intake ranges for twin-bearing ewes were 220 – 440, 350 – 700, 350 – 900 kJ per metabolic body weight (W^0.75) at week seven, five, two pre-partum respectively. Indirect calorimetry and a linear regression approach were used to quantify EE_gest and then partition to EE_conceptus and EE_homeorhetic. Energy expenditure of basal metabolism of the non-gravid tissues (EE_bmng), derived from the intercept of the linear regression equation of retained energy [kJ/W^0.75] and ME intake [kJ/W^0.75], was 298 [kJ/W^0.75]. Values of the intercepts of the regression equations at week seven, five, and two pre-partum were 311, 398, and 451 [kJ/W^0.75], respectively. The difference between the intercepts for different weeks was used to calculate EE_homeorhetic. The remaining part of EE_gest was considered to be EE_conceptus. In conclusion, the good agreement between our values of EE_conceptus and those in the literature indicates the method's validity.