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This study examined how a standard exercise test (SET) affected (1) thyroid hormones (THs) of horses and (2) the relationship between the V

International audience; The objective of this study was to explore how the endurance of five-year-old horses, kept out on pasture all their life and ridden for the first time well into their fifth year of age, developed within one year and compared to that of six-year-old horses raised under the same conditions and to other horses. Horses were submitted to a standardized exercise test (SET) to calculate their v 4 (velocity run under defined conditions inducing 4 mmol/L of blood lactate concentration (LA)) and v 180 (velocity run under defined conditions inducing a heart rate of 180 beats/min). The test consisted of up to five consecutive intervals at increasing speed until the blood LA of a horse increased above 4 mmol/L. The blood LA measured after each interval was plotted exponentially against running speed to derive v 4 from the blood lactate erunning speed relationship, and the mean heart rate during the intervals was plotted linearly against running speed to derive v 180 from the heart rateerunning speed relationship. The following were examined: (1) the development of v 4 and v 180 of five-year-old horses within one year through measurements in September and in the following July and September; the comparison of endurance variables (2) between five-year-olds and six-year-olds; (3) between six-year-olds on consecutive years; and 4) between six-year-olds and foreign horses. The results showed that: (1) there were no changes of either variable within one year (repeated measures ANOVA P > .05); (2) there were no significant differences between five-year-olds and six-year-olds (one-way ANOVA P > .05); (3) no significant differences between six-year-old groups (one-way ANOVA; P > 05); and (4) foreign horses had higher v 4 and v 180 values than six-year-olds (one-way ANOVA; P ¼ .0001 and P ¼ .003, respectively). There was no significant relationship between v 4 and v 180 (P > .05; r 2 ¼ 0.02). In conclusion, one additional year on pasture in multiage herds did not increase the endurance variables of five-year-old horses. Thus, the endurance appeared to be consolidated in these horses at the age of five years, and additional training seems to be necessary to increase it.

In endurance racing the heart rate (HR) of horses in the veterinary gates has to reach a maximum set to continue racing. There is no literature on the relationship between resting HR (HRresting) and HR after exercise (HRrecovery). This relationship was examined in seven horses and the results were related to their v4 (speed at which the blood lactate concentration is 4 mmol/L). Horses were submitted to an exercise test to determine v4. Thereafter, horses were exercised on a treadmill in randomized order for 10 and 60 min at different speeds. HR was measured before exercise and several times until 30 min of recovery. The relationship between HRresting and HRrecovery was significant in 16 out of 35 comparisons. There were no significant relationships between the v4 of the horses and their HRresting and between v4 and HRrecovery after 10 min of exercise, regardless of the speed of exercise, with one exception. The relationship between the v4 of the horses and their HRrecovery after 60 min of exercise was significant in the fifth minute after exercise at 3.5 m/s only. Conclusion: Because HRresting and HRrecovery are often related, pre-determined arbitrary HRrecovery values may not allow for fair competition during endurance racing., Facultad de Ciencias Veterinarias

BACKGROUND Blood is collected for hematologic and biochemical analyses when racehorses perform poorly. However, racing affects most analyte levels; therefore, the timing of blood sampling can affect analyte levels and interpretations. OBJECTIVE This study aimed to determine if the blood variable levels returned to pre-racing levels 2 and 3 days post-racing. METHODS Blood was sampled from 17 healthy racehorses pre- and post-racing. The variables measured from plasma were albumin, cholesterol, creatinine, calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na), potassium (K), creatine phosphokinase (CK), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), gamma-glutamyl transferase (GGT), and cortisol. Hematocrit (HCT), hemoglobin (HGB), white blood cell (WBC), red blood cell (RBC), granulocyte, and lymphocyte counts were analyzed from blood collected in EDTA-coated vials. RESULTS Calcium was lower 3 days post-racing compared with 2 days pre-racing (P

Global positioning systems (GPS) have become very popular tools to determine the running speed of horses. However, information on the accuracy of these measurements is scarce. The objective of this study was to examine the accuracy of speed determinations using GPS. For this purpose, the running speeds determined using the GPS of the Polar M400 Equine heart rate meter (G-speed) and a stopwatch (W-speed; manual division of the measured time over the distance run) were compared. The hypothesis was that the speeds determined by both methods would be the same. Eleven horses ran a standardized exercise test (SET) with 130 m laps, and 8 horses ran a SET with 250 m laps in two different sandy riding arenas (one was indoor). The length of the laps was determined with a distance measuring wheel and marked with red traffic cones for the riders to maintain an accurate course. The SETs consisted of five intervals at increasing speeds each. The duration of the intervals was between 3 and 6 minutes. Horses ran a defined number of laps in each interval to reach the prescribed durations. Data were analyzed using a paired Student's t-test; P.05 denoted significance. W-speeds differed from G-speeds for all intervals in both riding arenas (P between .01 and .001). G-speed was lower for each interval. With increasing speed, the difference between the two methods augmented. The hypothesis was rejected, therefore questioning the accuracy of the Polar M400 in determining speed under the conditions of this study.

The training of 19 show jumping horses was documented and related to the changes of v4 during an outdoor season (v4 = speed at which a blood lactate concentration of 4 mmol/L is achieved). Eleven of the horses were managed by a professional trainer (professional show jumpers) and the other horses by amateur riders (amateur show jumpers [ASJs]). All horses were submitted to three standardized exercise tests (SET) to calculate v4: April/May, June/July, and September: SET1, SET2, and SET3. The professional trainer recorded the training from 2 months before SET1 until SET3 and the amateur riders between SET1 and SET3. The duration of the specific exercises such as gymnastics, jumping, and others ranged between 30 and 60 minutes. Professional show jumpers were exercised less often, and the duration of each one of the specific exercises was lower than that for ASJs (P = .01). Considering all horses involved in the study, the v4 increased between SET1 and SET2 when the mean duration of all specific exercises together and of gymnastics only was longer, and the number of days on pasture was greater (P

Intensive short intervals of exercise are used to condition horses for racing. In this study, the effect of exercising horses one, two, or three times a week during 6 weeks using two intervals with near-maximal speed over 100 m on v4 (speed at which, under defined conditions, the blood lactate concentration reaches 4 mmol/L) and muscle thickness (MT) of supraspinatus and extensor carpi radialis was examined. Thoroughbreds (4-5 years of age) were exercised twice at near-maximal speed over 100 m, separated by a 10-minute period at walk, on dirt track during conditioning periods (CP) of 6-week duration. This exercise was undertaken once (six horses), twice (six horses), or thrice (five horses) a week during a CP. Before, every 2 weeks during, and 2 weeks after the CP, horses were subjected to a standardized exercise test to determine their v4. Before and after CP, the MT of the extensor carpi radialis and the supraspinatus was examined by ultrasonography. There was no differential effect of the number of weekly exercises on v4. Pooling the data of all horses, a decrease of v4 was found. The decrease became evident after the sixth week of conditioning. MT did not change. The results indicate that the examined exercise protocols could negatively impact racing performance of horses.

The effect of recovery from training has not been studied in horses. Therefore, the effect of recovery was examined with exercise of known effect within a conditioning period (CP). A standardized exercise test was performed at the beginning of CP to determine v 4 , v 10 , and v 180 (horse's speed, which produced a blood lactate concentration of 4 and 10 mmol/L and a heart rate of 180 beats/min). Six horses were conditioned for three periods of 2 weeks, 5 times per fortnight at their individual v 10 for two bouts of 5 minutes on a treadmill. Every 2 weeks of conditioning was followed by 1 week with reduced workload. Standardized exercise test was repeated after each 2 weeks of conditioning and 2 weeks after finishing CP. Exercise speed was individually adapted to the new v 10 for every 2 weeks of conditioning. In addition, peak oxygen consumption before, after 3 weeks of conditioning, and at the end of the CP was measured. The mean v 4 increased steadily during CP. v 180 did not change, whereas peak oxygen consumption increased between the beginning and after 3 weeks of conditioning and leveled off thereafter. In conclusion, reducing the workload for 1 week after 2 weeks of conditioning 5 times per fortnight at v 10 for two bouts of 5 minutes allowed for a continuous increase of v 4 , but the extent of the increase was smaller than in another study with a similar conditioning program but for the recovery week. The effect of recovery from training needs further studies.

This study examined the reproducibility and repeatability of muscle thickness (MT) measurements with ultrasound for the following muscles: extensor carpi radialis, extensor digitorum longus (both flexed and extended), gluteus medius, longissimus lumborum, semitendinosus, and supraspinatus. Three examiners measured thickness of these muscles in five Thoroughbreds on 3 consecutive days. The day of measurement did not have any effect on the mean MT value of the muscles examined ( P > .05). The left longissimus lumborum muscle was the only muscle for which the second measurement varied from the first and third ( P 10%– 3%–

This study examined the effect of exercising horses 3 times per week with two bouts of 5-minutes' duration at their v10. Six Thoroughbreds were treadmill-conditioned for 6 weeks. A standardized exercise test (SET) was performed at the beginning of the conditioning period to determine the blood lactate–running speed (BLRS) relation, and the SET was repeated every 2 weeks. After each SET, the BLRS relation was used to calculate the horse's speed, which produced a blood lactate (LA) concentration of 10 mmol/L (v10) and 4 mmol/L (v4). Each horse was then conditioned for the next 2 weeks (3 times/week) at its individual v10 for two 5-minute bouts with a 5-minute walking phase in between. Exercise speed was individually adapted to the new v10 every 2 weeks. The v4 of horses decreased after the first 2 weeks (from 6.23 ± 0.41 m/s to 5.95 ± 0.33 m/s, mean ± SD; P .05). The conclusion drawn was that exercising horses 3 times per week at their v10 for two 5-minute bouts did not improve v4.

The potential effect of herbs to treat lung, skin and gastrointestinal pathologies in horses is discussed. For lung pathologies effects of food supplementation with garlic, aniseed, fennel, licorice, thyme and hyssop have been found. A preparation of yellow gentian, garden sorrel, cowslip, verbena and common elder rendered recurrent airway obstruction affected horses less sensitive to histamine. For skin conditions flax seed and heartsease have a positive effect when fed on a regular basis. Aloe vera, along with chrysanthemum, relieves symptoms of dermatitis. Chamomile is one of the oldest known herbs with its anti-inflammatory properties. To manage gastrointestinal disturbances flax seed again is an important resource to support the symbiota. Fenugreek seed is also able to affect the microbiota stabilizing the immune system and Silybum marianum can also influence the gut to become healthy.

Introduction Exercising horses one, two, or three times per week during 6 weeks using two intervals with near-maximal speed over 100 m elicited a decrease of VLa4, a widely accepted parameter of fitness and competitive success of horses (speed at which, under defined conditions, the blood lactate concentration reaches 4 mmol/l). Therefore, two field studies were performed to examine the possibility of avoiding decline in VLa4 with this type of exercise. Methods Study 1) 6 horses were submitted to the same exercise as above once per week during the first 2 weeks of a conditioning period (CP) adding one interval in each exercise session every 2 weeks for the following 6 weeks. Study 2) 6 horses did the same as horses in study 1 plus once per week an exercise bout at their individual VLa2 during 35 minutes. Before, every 2 weeks during, and 2 weeks after the CP, horses were subjected to standardized exercise tests to determine their VLa4 (and VLa2 where convenient) and maximal speed (speedmax). The effect of conditioning on VLa4 and speedmax was examined using two-way repeated measures analysis of variance and Fisher's test. Results In study 1 mean VLa4 declined during the first 4 weeks of CP but increased to the initial level thereafter (P

Summary Reasons for performing study: There is limited published work on the effect of training using intensive and short intervals of exercise to condition horses for racing. Objectives: To examine the effect of conditioning horses 1, 2 or 3 x a week using 2 short fast exercise intervals on blood lactate (LA), plasma ammonia (NH3) and urea (urea) as well as creatine kinase (CK) activity. Methods: Thoroughbreds (age 4–5 years) were conditioned at near maximal speed (12–14 m/sec) over 100 m, on 2 occasions separated by a 10 min period at walk, on dirt track (conditioning exercise; CE) during a 6 week conditioning period (CP). The CE was undertaken either once (5 horses), twice (5 horses) or 3 times a week (4 horses) during a CP. Before, every 2 weeks during and after the CP, blood was drawn during the CE at 0, 2 and 4 min after each run and additionally 6 min after the 2nd run to measure blood LA and determine the maximal LA post exercise (LAmax). Plasma NH3 was measured in the same samples and the maximal NH3 post exercise (NH3max) determined. Additional blood samples were taken from the horses when stabled before the CE, and 12 and 24 h after to measure urea and CK activity in plasma. Results: There was no differential effect of the number of weekly CE on LAmax, NH3max, LA and NH3 immediately after exercise (LAO and NH30). Conditioning did not have an effect on LAmax and LAO after the 1st interval (P>0.05), but LAO after the 2nd interval was lower after conditioning. NH3max after the 1st and 2nd exercise interval decreased in response to the conditioning, but not NH3 immediately after exercise (P>0.05). Median plasma CK activity 12 h after exercise was higher than before exercise and returned to pre-exercise levels 24 h post exercise when horses were exercised once and twice/week. In contrast, the median plasma CK activity of horses exercising 3 times/week remained at the pre-exercise level 12 and 24 h post exercise (P>0.05). Conclusion: Conditioning horses with 2 intervals of 100 m at near maximal speed had a positive effect on blood LA and plasma NH3. Potential relevance: With the type of exercise examined, the fitness of racing horses can be maintained and eventually improved. In further studies the effect of increasing the number of runs in one exercise session should be investigated.

This study examined the effects of the intensity and duration of exercise on the nature and magnitude of training adaptations in muscle of adolescent (2–3 yr old) racehorses. Six thoroughbreds that had been pretrained for 2 mo performed six consecutive conditioning programs of varying lactate-guided intensities [velocities eliciting blood lactate concentrations of 2.5 mmol/l (v2.5) and 4 mmol/l (v4), respectively] and durations (5, 15, 25 min). Pre- and posttraining gluteus muscle biopsies were analyzed for myosin heavy chain content, fiber-type composition, fiber size, capillarization, and fiber histochemical oxidative and glycolytic capabilities. Although training adaptations were similar in nature, they varied greatly in magnitude among the different training protocols. Overall, the use of v4 as the exercise intensity for 25 min elicited the most consistent training adaptations in muscle, whereas the minimal training stimulus that evoked any significant change was identified with exercises of 15 min at v2.5. Within this range, muscular adaptations showed significant trends to be proportional to the exercise load of specific training programs. Taken together, these data suggest that muscular adaptations to training in horses occur on a continuum that is based on the exercise intensity and duration of training. The practical implications of this study are that exercises for 15 to 25 min/day at velocities between v2.5 and v4 can improve in the short term (3 wk) the muscular stamina in thoroughbreds. However, exercises of 5–15 min at v4 are necessary to enhance muscular features related to strength (hypertrophy).

Introduction One week of reduced workload between 3 periods of 2 weeks of conditioning (CP) 5 times/fortnight at VLa10 for two bouts of 5 minutes allowed for a continuous increase of VLa4, but the extent was smaller than in another study with the same conditioning program but for the recovery week (VLa4, VLa10: horse's speed, which produced a blood lactate concentration of 4 and 10 mmol/l). Methods Six Purebred Arabians were submitted to the same conditioning protocol of the studies mentioned above except for increasing the duration of treadmill exercise in each CP by 2.5 minutes (2 x 10 minutes in the third CP). A standardized exercise test (SET) was performed at the beginning of CP to determine VLa4 and VLa10, and repeated after the week with reduced workload after each CP. Exercise speed was individually adapted to the new VLa10 for every CP. The effects of conditioning on VLa4 were examined using repeated measures analysis of variance. Significant results were analyzed further with Fisher's test. Results Mean VLa4 increased after the first CP (P 0.05). Conclusions This conditioning program did not allow for VLa4 increases of the magnitude observed in other studies with the same exercise protocols but without the week with reduced workload and increases in exercise duration. It is possible that the decline of VLa4 of the horses after the first CP was due to overtraining (simultaneous increase of speed and duration of exercise). The effect of recovery from training needs further studies. Ethical Animal Research All procedures were approved by the Bioethical Committee of the University of La Plata, Argentina. Sources of funding: Verein zur Forderung der Forschung im Pferdesport, Germany. Competing interests: none.

Summary The effects of 3 different conditioning programmes on muscle glycogen concentration in horses were examined. Speed of exercise was selected according to the blood lactate values for each horse derived from a standardised exercise test before beginning a conditioning programme. Six 2-year-old Haflinger stallions were assigned randomly to one of 3 conditioning programmes according to a 6 × 3 latin square design: 45 min at their individual v1.5 or v2.5 and 25 min at v4. Each conditioning programme lasted 6 weeks (21 exercise sessions), followed by 5 weeks without conditioning (resting period). All exercise was carried out on a treadmill inclined at 17%. Muscle biopsies were taken 5 times from the gluteus medius muscle at 2 cm and 6 cm depth: before the start and in the middle of the conditioning period, then at Days 2, 9 and 35 after the last exercise session. It was found that glycogen concentration was not affected by conditioning until 9 days after finishing conditioning at v1.5 and v2.5 for 45 min (P