Stressful events during the prenatal period have been related to hyperactive hypothalamic–pituitary–adrenal (HPA) axis responses as well as metabolic changes in adult life. Moreover, regular exercise may contribute to the improvement of the symptoms associated with stress and stress-related chronic diseases. Therefore, this study aims to investigate the effects of exercise, before the gestation period, on the metabolic changes induced by prenatal stress in adult mice. Female Balb/c mice were divided into three groups: control (CON), prenatal restraint stress (PNS) and exercise before the gestational period plus PNS (EX + PNS). When adults, the plasmatic biochemical analysis, oxidative stress, gene expression of metabolic-related receptors and sex differences were assessed in the offspring. Prenatal stress decreased neonatal and adult body weight when compared to the pregestational exercise group. Moreover, prenatal stress was associated with reduced body weight in adult males. PNS and EX + PNS females showed decreased hepatic catalase. Pregestational exercise prevented the stress-induced cholesterol increase in females but did not prevent the liver mRNA expression reduction on the peroxisome proliferator-activated receptors (PPARs) α and γ in PNS females. Conversely, PNS and EX + PNS males showed an increased PPARα mRNA expression. In conclusion, pregestational exercise prevented some effects of prenatal stress on metabolic markers in a sex-specific manner.

The novel aim of this study was to describe the reference values of different haematological and biochemical parameters in the Spanish purebred horse (Andalusian, SPB) in each of the stages of a programmed exercise on a treadmill system, and to establish heritability and genetic correlations for these haematological and biochemical parameters. For this, 94 young SPB male horses (4.22 ± 2.27 years old) were used. An increasing intensity exercise test at 4, 5, 6 and 7 m/s was carried out on a treadmill (6% inclination). Total red blood cells, total white blood cells, neutrophils and lymphocytes counts; haematocrit, haemoglobin, lactate, uric acid, creatinine and total plasma proteins concentrations and aspartate transaminase, lactate dehydrogenase, creatine-quinase activities were determined. To conclude: (i) the reference values for each parameter were determined for each of the exercise test stages (ii) all the parameters analysed manifested a medium-high heritability and a high repeatability. These results will, in the near future, determine the measuring guidelines for improving the SPB horse's athletic ability on an objective treadmill system and for selecting these animals in response to those parameters.

Numerous studies have described the cardiorespiratory and kinematic responses of horses running on level and positive gradients, but little attention has been given to exercise on negative gradients, despite the fact that many horses compete over variable terrain. The purpose of this study was to describe the heart rate (HR), estimated net transport cost (COT) and stride characteristics of horses exercising at walk and trot on positive and negative gradients. Five horses (mean ± SD, 517 ± 42 kg) were acclimated in walk and trot on positive and negative gradients prior to data collection. HR and stride characteristics were measured over the last minute during walk (1.9 m s− 1) and trot (3.5 m s− 1) on a treadmill set at − 6, − 3, 0, 3 and 6%. Compared with level exercise, HR was higher at both 3 and 6%, and lower at − 3 and − 6% in walk and trot (P < 0.001). The estimated COT (beats kg− 1 m− 1 × 103) increased by an average of 30 and 48% at 3 and 6% gradient in walk, and by an average of 29 and 46% at trot compared with level exercise (P < 0.001), respectively. At negative gradients, COT decreased by 20 and 33% at walk, and by 17 and 24% at trot for − 3 and − 6% gradients (P < 0.001), respectively. Stride duration and stride length were longer, and stride frequency was lower at negative gradients compared with positive gradients (P < 0.001). In trot, the duty factor was increased in the forelimb and decreased in the hindlimb on negative compared with positive gradients (P < 0.001). Physiological workload in horses reduces from positive to negative gradients in walk and trot; however, the metabolic advantage of faster gaits, estimated by COT, diminishes as the gradient becomes more negative. This may reflect increased energy demands associated with maintaining balance and braking on negative slopes, and the locomotion strategy adopted.

The most popular techniques used for studying equine kinematics are videographic recording combined with the analysis using a commercial software package or optoelectronic systems based on emission and detection of infrared or visible light. Such systems can be expensive, complicated to use and their use may be restricted to indoor use (in the case of infrared systems) or a limited number of strides when used outdoors. Recently, there has been considerable interest in monitoring motion using inertial measuring systems. The purpose of the present study was to determine the accuracy of the Pegasus system (European Technology for Business Ltd., Codicote, UK), which determines stride frequency directly when mounted on the withers. Eight horses of different breeds and sizes (447–588 kg) were studied at walk, trot and two speeds at canter on a treadmill. Simultaneous measurements of stride were made using the Pegasus and ProReflex motion capture systems. Mean stride frequencies (n = 8 horses) for the ProReflex and Pegasus systems at walk (0.86 ± 0.05 and 0.87 ± 0.05 strides per second, respectively), trot (1.36 ± 0.07 and 1.36 ± 0.07 strides per second, respectively) and canter (7 m s− 1: 1.92 ± 0.05 and 1.92 ± 0.05 strides per second, respectively; 8 m s− 1: 1.93 ± 0.05 and 1.94 ± 0.05 strides per second, respectively) were not significantly different (P>0.05). The mean difference between the two systems for all four speeds was − 0.002 strides per second (lower 95% CI: − 0.016; upper 95% CI: 0.011; P = 0.309). In conclusion, the differences between stride frequency measurements made with the Pegasus and ProReflex systems in horses exercising at walk, trot and slow canter on a treadmill are < 1% and not likely to be of physiological significance.

Lameness manifests itself during the movement of the animal or at rest, indicating a structural or functional disturbance in one or more limbs. Videographic analyses allow the qualitative and quantitative investigation of the movement, reducing the subjectivity of evaluations. The objective was to record the alterations in the movement of the head and limbs of horses in a lame and non-lame condition. Video cameras (60 Hz) and computational methods were used. Six Purebred Arabian colts were filmed on a treadmill, at walk and at trot, before and after induction of lameness. Lameness was induced in the left forelimb utilizing a transient lameness model. Markers were placed on the zygomatic process of the temporal bone, spiny process of the sixth thoracic and first lumbar vertebrae and on the proximal phalange. Nine strides were analysed. At walk and at trot, the animals demonstrated two vertical head movements per stride, while after induction of lameness only one head movement was observed per stride, where this movement was of greater amplitude. The head was shown to be in a more elevated position when the lame limb made first contact with the treadmill belt, which was not observed in the case of the healthy limbs. Only with trotting did the lame animals manifest a prolonged duration of the stance phase for all limbs. The lame animals had a longer support time, lifted the non-lame limbs and showed a shorter stride. Videographic analyses offered details of the alterations in the movement of horses, which are important in the diagnosis of lameness.

Reasons for performing the study: In human exercise physiology, the current gold standard for evaluating aerobic capacity is the measurement of oxygen consumption (VO2) and maximal oxygen uptake (VO2max). The evaluation of VO2 in horses is performed in some laboratories equipped with a treadmill but has only been exceptionally reported in field conditions because of the lack of adapted equipment. Objectives: The aim of this study was (1) to assess the feasibility of VO2 measurement on the track using a recently validated portable breath-by-breath gas analyser system adapted to horses (Cosmed K4b2® and Equimask®), (2) to compare these results with those obtained during a treadmill exercise test and (3) to study correlations between VO2 and physiological parameters usually measured in field condition such as heart rate (HR), lactataemia (LA) and the speed at which HR equals 200 beats per minute (bpm) (V200) or LA 4 mmol l− 1 (VLA4). Methods: Five healthy Standardbred trotters in training were submitted to two stepwise incremental exercise tests, one driven on the racetrack and the other on a high-speed treadmill with a 4% incline. Speed (v), HR, ventilatory parameters and VO2 were continuously recorded throughout the duration of the tests and LA was evaluated after each step. Results: All horses completed the test satisfactorily after an initial acclimatization to the mask. There were marked individual differences in ventilatory strategy, and breathing frequency (Rf) at the higher levels of exercise was noticeably low. The VCO2 measurements were incoherent. There were no significant differences between track and treadmill maximal data obtained during the last step [VO2peak (track: 139.9 ± 8.9 ml kg− 1 min− 1; treadmill: 139.9 ± 13.4 ml kg− 1 min− 1), LAmax (track: 6.5 ± 1.6 mmol l− 1; treadmill: 7.3 ± 3.0 mmol l− 1), HRmax (track: 229 ± 6.2 bpm; treadmill: 222 ± 13 bpm)], although the maximal speed required to reach similar workloads was significantly higher on the track (11.9 ± 0.6 m s− 1vs. 9.7 ± 0.4 m s− 1). The correlation between VO2 and HR (r = 0.87; P < 0.001) and VO2 and LA (r = 0.75; P < 0.0001) during both tests was good but no correlation was found between VO2peak and HRmax, LAmax, V200 or VLA4. Conclusions: This is the first report of a practical portable system to measure VO2 and ventilation continuously during high-speed field exercise tests. However, current mask design markedly influences ventilation and could have prohibited the attainment of VO2max. Furthermore, consistent VCO2 measurements should be implemented by the manufacturers. Potential relevance: Continuous breath-by-breath ventilation and VO2 measurements can be recorded in horses in the field at submaximal levels. With necessary adaptations to the system entailed, this study opens new perspectives in the analysis of physiological and metabolic mechanisms of exercise in the equine species in genuine track conditions.

Several studies have shown that the placement of a face mask on a horse can have effects on ventilation, gas exchange and the cardiovascular system during exercise. The aim of the present study was to determine if airflow and ventilation measured with the same ultrasonic flowmeters were different during exercise between horses wearing half- (HM) and full-face (FM) masks. Five clinically healthy Thoroughbred horses with no history of respiratory disease were studied in an unbalanced crossover design. They were exercised on a treadmill at speeds between 1.7 and 11ms−1 on a 3° incline wearing both masks. The following variables were recorded: peak inspired (PIF) and peak expired flow rates (PEF), inspiratory tidal volume (VT), respiratory rate (fR ), inspiratory minute ventilation (VE), inspiratory time, (TI), expiratory time (TE ), total breath time (TT), end tidal oxygen (ETO2), end tidal carbon dioxide (ETCO2) and heart rate (HR). A mask by speed of exercise interaction term was not significant for any of the models. The PEF (mean difference 12.91s−1; lower and upper 95% CI 7.6 and 18.21s−1, respectively; P<0.0001) and ETO2 (mean difference 0.77%; lower and upper 95% CI 0.48 and 1.00%, respectively; P<0.0001) were significantly greater and ETCO2 was significantly lower (mean difference −1.3%; lower and upper 95% CI −2.0 and 0.7%, respectively; P<0.0001) with the FM compared with the HM. There was also a trend for inspired VE to be higher with the FM compared with the HM (mean difference 1021min−1; lower and upper 95% CI 26 and 1781 min−1, respectively; non-significant). We conclude that the HM may impair ventilation in the horse during exercise compared with the FM, despite the latter having a greater deadspace.

This study investigated the effect of training and exercise intensity on blood antioxidant markers in six healthy Standardbred horses. Markers studied were uric acid (UA), ascorbic acid (AA), α-tocopherol, vitamin A (Vit A), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione – reduced (GSH) and oxidized (GSSG), glutathione redox ratio (GRR), copper (Cu), zinc (Zn) and selenium (Se). The horses performed a standardized exercise test (SET) when they were untrained (T0), after 4 weeks of light training (T4) and after 8 weeks of interval training (T12). Forty-eight hours after SET T4 and SET T12, a SET with run up to fatigue (TTF4 and TTF12) was performed. Maximal oxygen consumption (V˙O2max) was determined within 3–5 days after TTF4 and TTF12. At each test (SET T(i) and TTF(i)), venous blood was sampled at rest (R), peak-exercise (Emax), 15 (E15) and 60 (E60) min after the test. UA, AA and GRR were increased significantly by the exercise, whereas GSH and Vit A were decreased significantly (P<0.05). Training-related increases (T0 vs. T4 vs. T12) were observed for UA, SOD, GPx and Se, whereas GSH, α-tocopherol and Zn decreased (P<0.05). Exercise intensity (TTF(i) vs. T(i)) increased UA and AA significantly and decreased GSH significantly (P<0.05). A significant correlation between ΔSOD and ΔV˙O2max (r=0.86, p<0.05) determined at SET T4 and SET T12 was found. Taken together, these results indicate that training and exercise intensity significantly influence blood antioxidant markers in healthy Standardbred horses.