Do racehorses and Greyhound dogs exhibit a gender difference in running speed?

At any level of competition, men run faster than women. Consequently, a male speed advantage is often presumed for other species. This assumption was tested in two animals bred for speed: horses and dogs. Results from Thoroughbred (TB), Standardbred (STB) and Greyhound (GH) races were analysed by ANOVA to compare the speeds of victorious males, neutered males (TB and STB only) and females. Separate analyses were run for shorter (TB: ≤ 1609 m, GH: 503 m) and longer (TB: >1609 m, GH: 603.5 m) TB and GH races. All STB races (trotters and pacers) were 1609 m. In TB races, intact males were 0.7% faster than females at ≤ 1609 m (n = 305; P < 0.01) and 1.4% faster at >1609 m (n = 194; P < 0.01). The speed of neutered males was equivalent to that of females at both distances. Gender accounted for 3.8 and 10.7% of the variance in speed at short and long distances, respectively. In STB pacers, intact males were 1.5% faster than females and gender accounted for 10.1% of the variance in speed (n = 96; P < 0.01). Gender was not a significant predictor of STB trotter (n = 95) or GH speed at 503 m (n = 146) or 603.5 m (n = 23). In conclusion, gender has a significant effect on speed of TBs and STB pacers. Although the effect size is small, it may be significant for racing; in a 7 furlong (1408 m) TB race, the 0.7% difference translates to an advantage of several lengths.

The effect of training on linear jumping parameters in young stallions

The aim of this study was to identify the effect of training stage, height of the obstacle and successive number of jump on young stallions' linear jumping parameters with and without rider. Investigations were based on filming of free jumping and jumping with rider during regular stallion work on the 11-month performance test. Horses jumped through the spread obstacle (doublebarre) with constant width of 90 cm and heights of 100, 110 and 120 cm. Taking-off distance, landing distance, heights of legs above obstacle and bascule of horse silhouette were measured using manual programme for video image analysis. Almost all parameters measured with and without rider were training dependent. The only parameters not affected by training were heights of hind limbs above obstacle, which were also not affected by height of obstacle in observations of more trained horses by free jumping and less trained horses with rider. Jumping parameters were not influenced by successive number of the jump by all parameters with rider and parameters of length of the jump in free jumping. On the basis of received results, it could be concluded that evaluation of jumping skills in free jumping and jumping with rider should be based on different criteria.

Effects of oral l-carnitine supplementation in racing Greyhounds

Abstractl-Carnitine supplementation can stimulate erythropoiesis, reduce exercise-induced plasma lactate concentrations and decrease post-exercise muscle damage. Next to horses, Greyhounds represent the premier animal racing species and perform short-duration, very high-intensity exercise that has the potential to incur substantial muscle damage. Under resting and standard racing conditions (5/16 mile), we tested the novel hypotheses that l-carnitine supplementation in Greyhounds would: (1) elevate haematocrit at rest and immediately post-exercise; (2) reduce peak post-exercise plasma lactate; and (3) reduce indices of muscle damage (plasma creatine phosphokinase, CPK and aspartate aminotransferase, AST). Six conditioned Greyhounds (30.1 ± 1.6 kg) underwent a randomized placebo-controlled crossover study to determine the effects of 6 weeks of l-carnitine supplementation (100 mg kg− 1 of body weight/day) at rest and following a maximal speed 5/16 mile race. In accordance with our hypotheses, l-carnitine elevated resting and immediately post-race haematocrit (control, 60.1 ± 1.7, l-carnitine, 63.6 ± 1.7; P < 0.05) and reduced peak post-race plasma CPK and AST concentrations (both P < 0.05). Those dogs with the highest peak post-exercise plasma CPK concentrations under placebo conditions evidenced the greatest reduction with l-carnitine supplementation (r = 0.99, P < 0.01). However, contrary to our hypotheses, l-carnitine did not change peak post-exercise plasma lactate concentrations (control, 27.0 ± 2.1, l-carnitine, 27.7 ± 1.3; P>0.05). We conclude that l-carnitine supplementation increases the potential for oxygen transport and reduces plasma indicators of muscle damage, CPK and AST in racing Greyhounds.

Muscle energetics in exercising horses

An optimally functional musculoskeletal system is crucial for athletic performance and even minor perturbations can limit athletic ability. The introduction of the muscle biopsy technique in the 1970s created a window of opportunity to examine the form and function of equine skeletal muscle. Muscle histochemical and biochemical analyses have allowed characterization of the properties of equine muscle fibres and their influence on, and adaptation to, physical exertion. Analyses of exercise responses during standardized treadmill exercise and field studies have illustrated the role of cellular energetics in determining athletic suitability for specific disciplines, mechanisms of fatigue, adaptations to training and the affect of diet on metabolic responses. This article provides a review of the tools available to study muscle energetics in the horse, discusses the muscular metabolic pathways and summarizes the energetics of exercise.

Origins of arterial and femoral venous acid–base responses during moderate-intensity bicycling exercise after glycogen depletion in men

The interactions between nutrition, energy status and acid–base balance during exercise are poorly understood. Exercise, under conditions of prior glycogen depletion (GD) and low-carbohydrate diet, results in a decreased rate of skeletal muscle glycogenolysis, greatly decreased muscle pyruvate and lactate contents with decreased plasma [lactate] (Putman et al., Am J Physiol, 265: E752, 1993). Therefore, it is hypothesized that exercise in GD, compared with normal (NG) or high-carbohydrate conditions, will result in a reduced magnitude of acidosis due to reduced production and accumulation of lactate. In two trials (GD, then NG) separated by 1–2 weeks, four men cycled at 75% of peak VO2 until the time of exhaustion in GD (57 ± 7 min). At 2 min of exercise, femoral vein (fv) plasma [H+] was increased by 21 ± 4 neq l− 1 (NG) and 14 ± 3 neq l− 1 (GD); increases in arterial [H+] were only c. 45% of those in fv plasma. The increase in fv PCO2 (NG, 25 ± 2 mm Hg and GD, 15 ± 2 mm Hg) was the primary variable responsible for the increased [H+]. During NG, the increase in fv [lactate− ] exceeded the decrease in strong ion difference [SID], with electrolyte charge balance mainly due to increased [Na+]. In the GD trial, arterial [SID] decreased and was the primary contributor to the increased [H+], as passage of blood through the lungs eliminated the CO2 contribution prevalent in fv plasma. Throughout GD, plasma [lactate− ] increased less than in NG and the decrease in [SID] in GD was also significantly less than in NG. In summary, in GD conditions, an attenuated production/release of lactate− and CO2 from muscle resulted in reduced magnitude and duration of acidosis compared with NG conditions. In fv plasma, increased PCO2 was the primary variable responsible for the rapid and sustained elevation in [H+], whereas in arterial plasma decreased [SID], due to increased [lactate− ], was primarily responsible for increased [H+].

Pre-race warm-up practices in Greyhound racing: a pilot study

Despite the high athletic demands of Greyhound racing and recommendations for the inclusion of pre-race warm-up by some veterinarians, the extent of warm-up practices by Greyhound owners and trainers remains unexplored. We postulated that little pre-race warm-up occurred and any warm-up activities were performed at random. A cross-sectional study design was used to examine pre-race warm-up practices in a sample of 80 Greyhounds. Warm-up components were recorded and scores were assigned in order to quantify the total amount of warm-up undertaken. Associations between total warm-up and signalment and race characteristics were analysed statistically. Correlations between total warm-up performed and all variables including race distance, race order, grade of Greyhound and trainer were poor (all r < 0.2). No statistically significant association between total warm-up and any variable examined could be demonstrated at the P = 0.05 level, although a weak trend towards graded Greyhounds performing more warm-up was noted (P = 0.09). We conclude that little pre-race warm-up is performed in Greyhounds and that when practised, the amount and methods of warm-up are inconsistently applied.

Electrolyte supplementation after prolonged moderate-intensity exercise results in decreased plasma [TCO2] in Standardbreds

The present study used the physicochemical approach to characterize the changes in acid–base status that occur in Standardbreds after post-exercise electrolyte supplementation. Jugular venous blood was sampled from six conditioned Standardbreds on two separate occasions, at rest and for 24 h following a competitive exercise test (CET) designed to simulate the speed and endurance test of a 3-day event. After the CETs, horses were given water ad libitum and either a hypotonic commercial electrolyte solution, via nasogastric tube followed by a typical hay/grain meal, or a hay/grain meal alone. The electrolyte supplementation resulted in c. 2 mmol l− 1 decreased plasma [TCO2] during the recovery period as compared with control. The primary contributor to the decreased [TCO2] with electrolyte supplementation was a decreased strong ion difference ([SID]), as a result of the non-significant increase in plasma [Cl− ]. Additionally, electrolyte supplementation resulted in faster restoration of hydration status compared with control, as evidenced by faster recovery of plasma [protein] and total weak acid concentration ([Atot]). It is concluded that oral administration of a hypotonic electrolyte solution after prolonged moderate-intensity exercise diminishes the post-exercise alkalosis, and that recovery of hydration status is still incomplete 24 h after exercise when no electrolytes are given. Thus, supplementation with electrolytes according to estimated sweat losses may attenuate post-exercise increases in plasma [TCO2], which is of significant practical interest to the horse racing community, as a testing threshold of greater than 37 mmol l− 1 is used by many racing jurisdictions to determine whether a horse has been administered an alkalinizing agent.

Supplementation of dietary long-chain polyunsaturated omega-3 fatty acids high in docosahexaenoic acid (DHA) increases plasma DHA concentration and may increase trot stride lengths in horses

Twelve mature and six 2-year-old Arabian horses were used to determine the effect of dietary long-chain polyunsaturated omega-3 fatty acid supplementation on plasma fatty acids and lameness. Lameness scores and stride lengths were measured on day 0. Horses were striated and pair-matched according to age, gender, stride length and, for mature horses, lameness score, and each horse was fed either a treatment diet containing 5.95 g of stabilized omega-3 fatty acids plus a fat carrier (FA), for a total of 19.4 g fat, or a control diet containing 49 g of corn oil (CO) for 75 days. Horses were exercised 5 d week− 1, and blood samples were drawn and body weights recorded on days 0, 25, 50 and 75. Lameness scores and stride lengths were recorded again on day 75. Total plasma omega-3 fatty acid concentrations were higher on all days in FA horses than in CO horses. Total plasma omega-6 fatty acids increased from days 0 to 25, remained elevated through day 50 and returned to baseline on day 75 in all horses. The ratio of plasma omega-6:omega-3 fatty acids was lower in FA horses. Horses on FA had increased plasma docosahexaenoic acid (DHA) on days 25, 50 and 75. No difference in walk stride length was noted; however, FA horses tended to have a longer trot stride after supplementation when compared with CO horses. No differences were seen in prostaglandin E2 (PGE2) metabolite or tumour necrosis factor-α as measured in blood serum. In summary, supplementing omega-3 fatty acids increases plasma DHA, although there was no overall increase in omega-3 in FA horses. While a trend to increase trot stride length was seen, no differences in lameness scores between treatments were noted.

Effects of endurance training on VO2max and submaximal blood lactate concentrations of untrained sled dogs

Five previously untrained yearling sled dogs were evaluated for endurance training-induced changes in maximum oxygen consumption (VO2max) and submaximal blood lactate concentrations. Following 3 weeks of light training followed by 4 weeks of moderate training, VO2max increased by 10%, from 180.2 ± 9.9 to 198.7 ± 19.2 ml kg min− 1 (P = 0.046). Light training was not associated with any increase in VO2max. Blood lactate concentrations at the same absolute intensity decreased by 215%, from 9.2 ± 4.7 to 4.3 ± 2.4 mmol l− 1 (P = 0.022). Speeds associated with oxygen consumptions of 70% VO2max increased by 12%, from 4.8 ± 0.4 to 5.4 ± 0.5 m s− 1 (P = 0.008) and speeds associated with VO2max increased by 21%, from 6.7 ± 0.3 to 8.2 ± 0.7 m s− 1 (P = 0.012).

Segmental variation in the activity and function of the equine longissimus dorsi muscle during walk and trot

Muscle function depends in part on the interplay between its activity and its length within the stretch-shortening cycle. The longissimus dorsi is a large epaxial muscle running along the thoracic and lumbar regions of the equine back. Due to its anatomical positioning, the longissimus dorsi has the capability of contributing to many functions: developing bending moments in the dorsoventral and lateral (coupled to axial rotation) directions and also providing stiffness to limit motion in these directions. We hypothesize that the exact function of the longissimus dorsi will vary along the back and between gaits as the relation between activity and motion of the back changes. Electromyograms (EMG) were recorded at walk (inclined and level) and trot (on the level) on a treadmill from the longissimus dorsi at muscle segments T14, T16, T18 and L2. Back motion was additionally measured using a fibre-optic goniometer. Co-contractions of the muscle between its left and right sides were quantified using correlation analysis. A greater dominance of unilateral activity was found at more cranial segments and for level walking, suggesting a greater role of the longissimus dorsi in developing lateral bending moments. Timing of the EMG varied between muscle segments relative to the gait cycle, the locomotor condition tested and the flexion–extension cycle of the back. This supports the hypothesis that the function of the longissimus dorsi changes along the back and between gaits.