bluuebunny/crossref_metadata_2025_split huggingface dataset:
Treadmill exercise‐induced tendon hypertrophy: assessment of tendons with different mechanical functions
Authors: BIRCH HELEN L. , McLAUGHLIN LUCY , SMITH R. K. W. , GOODSHIP A. E. 
Published: June 2010

SummaryThe equine superficial digital flexor tendon (SDFT) functions as an energy store during high‐speed gaits reducing the energetic cost of locomotion. To enable the SDFT to function effectively, the appropriate mechanical properties are essential. We tested the hypothesis that the SDFT does not undergo gross hypertrophy in response to high‐intensity exercise whereas tendons not involved in energy storage undergo adaptive hypertrophy. Two groups (n=6) of Thoroughbred fillies were trained at high‐intensity on a highspeed equine treadmill for 5 months (short‐term study) or 18 months (long‐term study). Age‐matched groups (n=6) of horses undertook low‐intensity exercise only for the same time period. Throughout the short‐term study the SDFT and deep digital flexor tendon (DDFT) were ultrasonograpically scanned at mid‐metacarpal level and cross‐sectional area (CSA) calculated. At the end of the short‐term study (horse age=2 years) and long‐term study (horse age = 3 years) the left SDFT, DDFT, suspensory ligament (SL) and common digital extensor tendon (CDET) were harvested and CSA calculated. Comparison of the DDFT from 2‐ and 3‐year‐old horses revealed an age‐related increase in CSA which was confirmed by ultrasonographs.Post mortemanalysis showed a significant hypertrophy of the CDET with high‐intensity training in the short‐term study (younger horses). CSA did not differ significantly between training groups for any of the structures following long‐term training. These results suggest a structure specific hypertrophic response to the imposed training regime.
An MRI study of the effect of treadmill training on bone morphology of the central and third tarsal bones of young Thoroughbred horses
Authors: WHITTON R. C. , MURRAY RACHEL. C. , BUCKLEY C. , GOODSHIP A. E. , LEKEUX P. 
Published: June 2010

SummaryTraining results in marked modelling of the subchondral bone of the carpus, but the effect of training on the subchondral bone of the distal tarsal joints is unknown. The aim of this study was to determine whether training influenced modelling of the third and central tarsal bones in Thoroughbred horses. Twelve untrained Thoroughbred horses were divided into 2 groups.Group 1underwent a 19 week progressive training regimen on a high speed treadmill.Group 2were walked for 40 min daily. Images of left tarsi were obtained by magnetic resonance imaging (MRI) with a 0.5 Tesla superconducting magnet using a spin echo sequence. Sagittal and oblique sagittal slices were made perpendicular to the articular surfaces of the intertarsal joints and were analysed using image analysis software to measure the proportion of dense subchondral bone in the dorsal facet of each bone. Mean ± s.d. percentage area of dense subchondral bone in the dorsal facet of the central tarsal bone inGroup 1was 47 ± 8 medially, 46 ± 4 sagitally and 50 ± 11 dorsolateral, whereas inGroup 2it was 39 ± 16 medially, 43 ± 8 sagitally and 53 ± 7 dorsolateral. For the third tarsal bone mean ± s.d. percentage area of dense subchondral bone inGroup 1was 32 ± 10 medially, 39 ± 11 sagitally and 44 ± 8 dorsolateral, whereas inGroup 2it was 28 ± 8 medially, 37 ± 6 sagitally and 41 ± 9 dorsolaterally. There was no significant difference in percentage area of dense subchondral bone between the trained and untrained horses. An effect of treadmill training of Thoroughbred horses on modelling of the central and third tarsal bones could not be demonstrated.
Radiographic measures of bone shape in young Thoroughbreds during training for racing
Authors: DAVIES HELEN M. S. , GALE SUSAN M. , BAKER I. D. C. 
Published: June 2010

SummaryThe aim of this study was to determine if changes in the shape of the third metacarpal bone (MC3) during the first preparation for racing in young Thoroughbred racehorses could be measured radiographically. Lateral radiographs of each MC3 were taken when the horses commenced training, every 2 weeks for 10 weeks, and again at 6 months after the start of training. The width of the dorsal cortex (DC), palmar cortex (PC), and medulla (M) were measured at a position 2.5 cm distal to the nutrient foramen before the subject of each radiograph was identified. The following ratios were calculated: z=DC/M; RI = [(DC+PC)/M]x[DC/PC]. The results showed that the shape of the MC3 changed during training for racing and that these changes may be measured on standard lateral radiographs. The dorsal cortex became proportionately thicker than the rest of the bone dimensions in the dorsopalmar plane. The proportionate increases in dorsal cortex dimensions were greater in horses that were recorded as shin sore during racing than in horses that were racing with no recorded shin soreness.
Nerve block and intra‐articular anaesthesia of the forelimb In the sound horse
Authors: DREVEMO S. , JOHNSTON C. , ROEPSTORFF L. , GUSTåS PIA 
Published: June 2010

SummaryNerve blocks and intra‐articular anaesthesia are used extensively as routine methods in lameness evaluation. The method is based on the assumption that the technique itself does not change the movement pattern. The aim of this study was to carry out a quantitative kinematic study to confirm or reject the hypothesis that high palmar digital nerve block (HPDN) and intra‐articular fetlock joint anaesthesia (IAF) influence significantly the movement pattern of the horse.Seven Standardbred horses trotting at 4.5 m/s were recorded at 240 Hz on a treadmill before and after anaesthesia by use of a ProReflex video system. Time variables, segment and joint angles were calculated. The high palmar digital nerve block (HPDN) resulted in a longer stance time and caused a greater fetlock joint angle range and greater maximal pastern joint angle. No systematic differences in time and angle variables were observed after intra‐articular fetlock joint anaesthesia (IAF). In conclusion, HPDN but not IAF affects locomotor pattern in sound horses. Distal limb proprioception is important in normal movement, while fetlock intra‐articular proprioception is apparently not. Interpretation of the effect of HPDN in lame individuals should incorporate more variables than maximal overextension of the fetlock joint.
The effect of training on the calcified zone of equine middle carpal articular cartilage
Authors: MURRAY RACHEL C. , WHITTON R. C. , VEDI S. , GOODSHIP A. E. , LEKEUX P. 
Published: June 2010

SummaryCarpal osteochondral injury is frequently observed in strenuously trained horses. It is clear that the integrity of articular cartilage and subchondral bone are intimately related, although there is controversy about which component is the most important. Calcified cartilage provides the mechanical link between soft hyaline cartilage and stiff subchondral bone so it is essential to understand the tissue's response to exercise. Middle carpal calcified and uncalcified (hyaline) cartilage thickness was investigated in horses undergoing high‐ and low‐intensity exercise. Twelve untrained horses (18–21 months) were paired, and randomly assigned to an exercise group.Group 1underwent 19 weeks progressive high‐intensity training on a high‐speed treadmill.Group 2underwent walking exercise only. Osteochondral specimens were obtained from 8 test sites per carpus immediately after euthanasia. Histomorphometric measurements of total cartilage, hyaline layer, and calcified zone thickness were obtained from decalcified and undecalcified samples. Mean ± s.d. (μm) calcified cartilage thickness for dorsal cartilage fromGroup 1was 271 ± 73 and fromGroup 2was 163 ± 49; for palmar cartilage fromGroup 1was 195 ± 42 andGroup 2was 150 ± 52.Group 1horses had significantly thicker total cartilage (P<.0001) and calcified zone (P<.0001) thanGroup 2, but there was no difference in hyaline layer. Within each group all dorsal sites had thicker calcified cartilage (P<.003) than palmar sites, but no difference in hyaline or total cartilage. These findings indicate that high‐intensity exercise leads to greater calcified zone depth without alteration in hyaline cartilage thickness, and that this response is maximal at sites that withstand high, intermittent loads. Increasing calcified cartilage thickness with exercise may maintain the articular surface stiffness gradient in the face of alterations in hyaline cartilage and/or subchondral bone stiffness.
Muscle adenine nucleotide degradation during submaximal treadmill exercise to fatigue
Authors: ESSÉN‐GUSTAVSSON BIRGITTA , GOTTLIEB‐VEDI MARIANNE , LINDHOLM A. 
Published: June 2010

SummaryThe aim was to investigate metabolic response in muscle during submaximal treadmill exercise to fatigue, with a special emphasis on adenine nucleotide degradation products such as inosine monophosphate (IMP) in muscle and hypoxanthine, xanthine and uric acid in plasma. Five Standardbred trotters performed treadmill exercise on 2 occasions, once at 7 m/s and once at 10 m/s. Venous blood samples were taken at rest, during exercise and at the end of exercise. Muscle biopsies were taken before and after exercise and muscle temperature was measured before and after exercise. Running time differed among horses and was 48–58 min at 7 m/s and 10–15.5 min at 10 m/s. Both lactate and uric acid concentrations in plasma showed a gradual increase during exercise at both 7 and 10 m/s. At the end of exercise, values for uric acid were higher and values for lactate lower at 7 m/s compared with at 10 m/s. No marked changes were seen in plasma concentrations of hypoxanthine or xanthine with exercise.Muscle glycogen decreased after exercise at both 7 and 10 m/s with a marked depletion seen in some fibres. Muscle lactate concentrations increased after exercise at both 7 m/s and at 10 m/s. No significant changes were seen in adenosine triphosphate (ATP), ADP and AMP concentrations, whereas IMP concentrations increased after exercise at both 7 m/s and at 10 m/s. The results of this study indicate that AMP deamination occurs with submaximal exercise and that development of fatigue may be related to adenine nucleotide degradation in muscle.
Skeletal muscle Na+‐K+‐ATPase and K+homeostasis during exercise: effects of short‐term training
Authors: McCUTCHEON L. JILL , GEOR R. J. , SHEN HUA 
Published: June 2010

SummaryThe objective of this study was to determine the effects of 10 consecutive days of moderate intensity training on 1) the concentration of middle gluteal muscle Na+‐K+‐ATPase as determined by vanadate‐facilitated [3H]ouabain binding; and 2) plasma potassium regulation before, during and after exercise at 100% of the pre‐training maximum rate of oxygen consumption (V̇o2max). Six mature, unfit Thoroughbred horses completed both incremental (for determination of V̇o2max) and high‐intensity exercise protocols before (HI1) and after (HI2) training. Three additional horses undertook no training or exercise tests and served as controls for determination of middle gluteal muscle Na+‐K+‐ATPase concentration. Training consisted of 10 consecutive days of running at 55% V̇o2maxfor 60 min per day (13–14 km/day). For each high intensity exercise protocol, horses completed a 10 min warm‐up at 50% V̇o2max, followed by exercise at 100% of pre‐training V̇o2max(6° incline, mean speed 9.8 m/s) until fatigue. Training resulted in a 13.8% increase in resting plasma volume (pre: 20.9 ± 0.8 1; post: 23.8 ± 0.9 1; P = 0.03), and an 8.9% increase in V̇o2max(pre: 142 ± 4 ml/kg/min; post: 155 ± 4 ml/kg/min; P=0.004) during HI. Peak values for plasma potassium concentration and content during exercise decreased by 13% (P=0.02) and 7% (P = 0.0002), respectively, after training whereas training had no effect on increases in packed cell volume, plasma total solids, and erythrocyte K+concentration and content during exercise. Following training, there was also a significant (23%) increase in Na+‐K+‐ATPase concentration in biopsies of middle gluteal muscle, as measured by vanadate‐facilitated [3H]ouabain binding. We conclude that 10 days of moderate intensity exercise results in increases in skeletal muscle Na+‐K+‐ATPase and attenuation in the elevation in plasma K+during high intensity exercise at the same absolute workload. The increase in middle gluteal muscle Na+‐K+‐ATPase concentration is consistent with decreases in K+efflux from working muscle during exercise.
Skeletal myosin heavy chain composition and carriage training
Authors: RIVERO J. L. L. , SERRANO A. L. 
Published: June 2010

SummaryThree different myosin heavy chain (MHC) isoforms have been identified in the equine gluteus medius muscle: the slow or MHC‐I and the 2 fast MHC‐IIA and MHC‐IIX isoforms. They are distributed in 3 fibre types containing a single MHC (I, IIA, IIX) and 2 hybrid types co‐expressing 2 isoforms (I+IIA, IIA+IIX). The aim of this study was to determine if heavy carriage training alters skeletal MHC composition in horses. Fourteen Andalusian mares age 42–46 months were used. Seven horses were used as controls to estimate the effects of growth on muscle. The remaining 7 horses underwent a training programme based on carriage exercise for 8 months. The intensity of exercise was individually adjusted to each horse according to a standardised exercise test. Gluteus medius muscle biopsies were analysed biochemically for MHC composition by electrophoresis, immunohistochemically for fibre types with specific anti‐MHC monoclonal antibodies, and histochemically for fibre type areas, fibre oxidative capacity and capillaries. After training, MHC‐IIIX decreased and MHC‐I increased. The percentages of type IIX and IIAX (i.e. fibres co‐expressing MHCs IIA and IIX) fibres decreased, whereas the percentage of type I fibres increased. Neither MHC‐IIA composition nor type IIA fibre percentage changed with training. The training had no significant effect on fibre areas and capillaries, but the percentage of fibres with high oxidative capacity increased. The control group showed no changes in muscle variables after the 8 month training period. These results suggest that carriage training alters MHC composition in equine skeletal muscle, reflecting a conversion of MHC isoforms in the order IIX→ IIA→ I and suggesting a reduction in the velocity of shortening of the muscle, but an increase in fatigue resistance.
Blood glucose clearance after feeding and exercise in polysaccharide storage myopathy
Authors: DE LA CORTE F. D. , VALBERG STEPHANIE J. , MICKELSON J. R. , HOWER‐MORITZ MELISSA 
Published: June 2010

SummaryPolysaccharide storage myopathy (PSSM) in Quarter Horses (QH) and QH crosses is a glycogen storage disorder in which blood glucose clearance and insulin sensitivity, following an i.v. or oral glucose challenge, are enhanced. Exercise is known also to enhance glucose uptake into skeletal muscle in many animal species. Therefore, the purpose of this study was to compare the effect of exercise on glucose clearance in PSSM and control horses when an oral carbohydrate meal (8 Mcal sweet feed) was fed following either 12 h fasting alone (NEX protocol) or following fasting and a standard exercise protocol (EX protocol). In the NEX protocol, horses fasted 12 h and then were fed 8 megacalories (Meal) of sweet feed (2.3 kg). In the EX protocol, horses were fed sweet feed 2 h after an exercise test (SET). Blood glucose was analysed for >480 min after feeding. Muscle biopsies were taken before and after the EX protocol. With the NEX protocol, the mean of all blood glucose and insulin concentrations were significantly lower in fed‐PSSM horses than controls (P<.013). The EX protocol in control horses caused a less pronounced percentage change in glucose concentration from baseline following feeding compared to the NEX protocol (mean peak EX 26.5% vs. NEX 70.2%, respectively) (P<.0003). In PSSM horses, the EX protocol also resulted in a lower percent change in glucose concentration following feeding compared to the NEX protocol (44.7 vs. 67.5%, respectively) (P=0.021). The magnitude of the difference in percentage change of blood glucose concentration with the EX protocol was less in PSSM than that seen for controls (mean peak PSSM‐EX 44.7% vs. 26.5% for controls, respectively) (P<.006). No significant differences in the insulin:glucose ratios were found for control horses between NEX and EX. In PSSM horses, the insulin:glucose ratio was significantly increased in the EX vs. NEX. In conclusion, exercise in normal horses results in enhanced glucose clearance following feeding without altering insulin:glucose ratios. At rest, PSSM horses have lower insulin:glucose ratios after feeding than normal horses, however, exercise in PSSM horses significantly increases insulin:glucose ratios. This may explain the beneficial effect of daily exercise for preventing rhabdomyolysis in horses with PSSM.
Effects of conditioning horses with lactate‐guided exercise on muscle glycogen content
Authors: GANSEN SILKE , LINDNER A. , MARX S. , MOSEN H. , SALLMANN H.‐P. 
Published: June 2010

SummaryThe 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 individualv1.5orv2.5and 25 min atv4. 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 thegluteus mediusmuscle 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 atv1.5andv2.5for 45 min (P<.05). By this time glycogen concentration in the muscle samples taken at 6 cm depth increased by 47 and 48%, respectively, and remained elevated until the end of the resting period.It was concluded that conditioning at lower intensity and for longer duration seemed to increase glycogen stores in the muscle while faster intensity but shorter duration exercise did not. To increase the likelihood of measuring effects of conditioning programmes on muscle variables, sampling should be done at different depths of a muscle and at several days after finishing a conditioning programme.
Contributions of equine exercise physiology research to the success of the 1996 Equestrian Olympic Games: a review
Authors: JEFFCOTT L. B. , KOHN C. W. 
Published: June 2010

SummaryFollowing public concern about the weather conditions for the 1996 Olympic Games in Atlanta an international research programme was initiated. The primary objective of this effort was to identify strategies for ensuring welfare of horses competing in the heat. Field observations of horses during the endurance test of 3‐day events in Europe, Canada, and the USA characterised the work effort of this form of competition; laboratory treadmill studies assessed limitations to performance of heat and humidity, explored the relationships of thermoregulatory demands to the phases of the competition and documented fluid and electrolyte losses. Estimates of energy expenditure and heat production during the endurance test were made. Strategies for facilitating heat dissipation were also studied in depth. Assessment of the effect of environmental conditions was based upon intensive climate monitoring using a modification of the Wet Bulb Globe Temperature index. Studies of heat acclimation provided a basis for recommendation of acclimatisation times for horses before the Games. The results of all these studies guided the management of equine athletes at the 1996 Olympic Games and significantly advanced knowledge of thermoregulation in competitive horses.
Thermoregulatory strategies during short‐term exercise at different intensities
Authors: SCOTT CAROLINE M. , MARLIN D. J. , SCHROTER R. C. 
Published: June 2010

SummaryPreviously we have observed a decline in sweating rate (SR) during high intensity exercise in an incremental test protocol. In man, the sweating sensitivity (SR/°C) has been shown to vary with exercise intensity. The aim of the present study was to determine if thermoregulatory responses in the horse, a prolific sweater with a high rate of metabolic heat production, were modified by exercise intensity. The effect of 3 separate exercise intensities (50 (S), 70 (M) and 90% (F) V̇o2Peakon neck (SRN) and gluteal sweating rate (SRG), pulmonary artery (TPA), rectal (TREC) and skin temperatures on the neck (TSK‐N) and gluteal region (TSK‐G) were investigated. Horses were exercised for ˜2 min at each exercise intensity in a randomised order. The rate of increase in TPAincreased with exercise intensity (P<.05) (0.27 ± 0.05, 0.43 ± 0.04 and 0.77 ± 0.05°C/min during S, M and F, respectively. The TPAand TSKtemperatures at the onset of sweating were not different between exercise intensities (P>0.05). Despite the increased rate of heat production with increasing exercise intensity, sweating sensitivity decreased on both the neck [(P<.05) (18.2 ± 3.4 (S), 12.0 ± 3.5 (M) and 2.9 ± 0.7 (g/m2/min)/°C (F)] and gluteal region [(P<.05) (8.9 ± 2.0 (S), 5.1 ± 1.7 (M) and 0.8 ± 0.3 (g/m2/min)/°C (F)]. During exercise at 90% V̇o2peaksweating sensitivity and the rate of increase in skin temperature were markedly reduced compared to at 70% V̇o2peak. The present investigation demonstrates that the drive to thermoregulate is overridden during short‐term, high‐intensity exercise, resulting in greater heat storage (TPA) as a result of a lower SR sensitivity.
Effects of frusemide on electrolyte and acid‐base balance during exercise
Authors: CARLSON G. P. , JONES J. H. 
Published: June 2010

SummaryThis study was undertaken to evaluate the effects of frusemide on the concentration of plasma electrolytes and the relationship between changes in electrolyte concentration and the simultaneous changes in acid‐base balance in arterial and venous blood during intense exercise. Five exercise‐conditioned Thoroughbred horses were exercised on a highspeed treadmill at a slope of 10% at speeds known to exceed V̇o2max. Horses participated in 3 randomised exercise trials in which they received either placebo (control), low‐dose frusemide (0.5 mg/kg bwt), or high‐dose frusemide (1.0 mg/kg) 4 h prior to exercise. Arterial and mixed venous blood samples were drawn before, during and after intense exercise. Packed cell volume (PCV), plasma protein, plasma electrolyte, plasma lactate concentrations and acid‐base balance were determined. Frusemide at both dosages induced a significant metabolic alkalosis associated with a decrease in plasma [chloride] in both arterial and mixed venous blood. There was a highly significant correlation between the strong ion difference (SID) and [bicarbonate] in all blood samples. The effects of frusemide on electrolyte concentration and acid‐base balance were largely due to changes in SID.