To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
The ability to use oxygen during exercise is determined by a combination of the muscle mitochondrial density, the relative proportion of total body mass consisting of locomotory muscle, the gas exchange surface area and the capacity for conduction of oxygen from the gas exchange surface to the muscle cells, i.e. the heart and circulation. Other factors include: the ability to ventilate the lungs to ensure that a high gradient is maintained between the alveolar oxygen tension and that in the pulmonary capillaries to facilitate diffusion; the capillary density within muscle, the size of the muscle cells and the blood oxygen carrying capacity, which is primarily determined by the total blood volume and haemoglobin concentration.
In absolute terms, the fastest animal on land is the Cheetah, which can reach speeds of up to 120 kmh. However, the Cheetah is a “sprinter” and can only achieve these speeds for distances of around 200 metres (<10 seconds).
Oxidative stress occurs when antioxidant defence mechanisms are overwhelmed by free radicals and may lead to damage to DNA, which has been implicated in processes such as ageing and cancer. The Comet assay allows detection of oxidative DNA damage in individual cells. As horses with recurrent airway obstruction (RAO) have been shown to demonstrate low antioxidant status and oxidative stress, we hypothesised that peripheral blood mononuclear cells (PBMC) of horses with RAO would demonstrate increases in DNA damage following natural allergen challenge.
Six horses (mean age 15 years, range 8-23 years) diagnosed with RAO (in remission) and 6 healthy breed matched controls (mean age 9 years, range 5-15 years) were studied. Blood samples were collected 7 days prior to challenge and immediately and 3 days after stabling on mouldy hay and straw for 24h. All animals were kept at grass prior to and after the challenge period. Bronchoalveolar lavage (BAL) was performed and neutrophil counts determined.
Due to poor weather conditions including common heavy cloud cover at polar latitudes, daily satellite imaging is not always accessible. Nevertheless, fast events including heavy rainfall inducing floods appear as significant in the ice and snow budget while being ignored by satellite based studies since the slower sampling rate is unable to observe such short phenomena. We complement satellite imagery with a set of ground based autonomous automated high resolution digital cameras. The recorded oblique views, acquired at a rate of 3 images per day, are processed for comparison with the spaceborne imagery. Delaunay triangulation based mapping using a dense set of reference points provides the means for an accurate projection by applying a rubber sheeting algorithm. The measurement strategy of identifying binary information of ice and snow cover is illustrated through the example of a particular flood event. We observe a snow cover evolution from 100% to 44.5% and back to 100% over a period of 2 weeks.
The volume variation of a glacier is the actual indicator of long term and short term evolution of the glacier behaviour. In order to assess the volume evolution of the Austre Lovénbreen (79° N) over the last 47 years, we used multiple historical datasets, complemented with our high density GPS tracks acquired in 2007 and 2010. The improved altitude resolution of recent measurement techniques, including phase corrected GPS and LiDAR, reduces the time interval between datasets used for volume subtraction in order to compute the mass balance. We estimate the sub-metre elevation accuracy of most recent measurement techniques to be sufficient to record ice thickness evolutions occurring over a 3 year duration at polar latitudes.
The systematic discrepancy between ablation stake measurements and DEM analysis, widely reported in the literature as well as in the current study, yields new questions concerning the similarity and relationship between these two measurement methods.
The use of Digital Elevation Model (DEM) has been an attractive alternative measurement technique to estimate glacier area and volume evolution over time with respect to the classical in situ measurement techniques based on ablation stakes. With the availability of historical datasets, whether from ground based maps, aerial photography or satellite data acquisition, such a glacier volume estimate strategy allows for the extension of the analysis duration beyond the current research programmes. Furthermore, these methods do provide a continuous spatial coverage defined by its cell size whereas interpolations based on a limited number of stakes display large spatial uncertainties. In this document, we focus on estimating the altitude accuracy of various datasets acquired between 1962 and 2010, using various techniques ranging from topographic maps to dual frequency skidoo-tracked GPS receivers and the classical aerial and satellite photogrammetric techniques.
Human genomic structural variation (SV) is significant factor in genome complexity, and thus has substantial implications to the cause, development and progression of genetic diseases. These SVs, ranging in size of 1kbp-1Mbp, are challenging to assess with current technologies. As such, we have developed a commercial system (nanoAnalyzer® 1000) for the rapid linear analysis of genomes at single-molecule level.
The core of our system is a nanofluidic chip consisting of an array of channels with a diameter less than 100 nm, nanofabricated on the surface of a silicon substrate. Thousands of unamplified genomic DNA molecules of 100’s kbps to several Mbps can be isolated and linearly streamed into the array for analysis in a parallel fashion. Fluorescently labeled sequence-specific signatures can then be identified and aligned to reference patterns at high resolution with custom software. This automated, multi-color imaging platform will enable a wide range of applications, such as accurate sequencing assembly, discovering genome structural variations, and uncovering epigenomic content. Nanochannel arrays promise to substantially lower the barriers of entry for single-molecule DNA analysis for scientists and clinicians, greatly impacting the advancement of molecular diagnostics, personalized medicine, and biomedical research.
A new series of Sm(CowFevCuxZry)z magnet products with 1Hc up to 13 kOe at 400°C has been developed. These magnets have low temperature coefficients of iHc and a straight line B vs. H (extrinsic) demagnetization curve up to 550°C. A straight line extrinsic curve provides greater design flexibility and facilitates reduced size and weight of magnetic circuits. The straight line extrinsic demagnetization B curves are required for magnets used in dynamic applications. The maximum use temperature, defined here as TM, can be determined by finding the maximum temperature at which the B curve is a straight line. The results of this work show that increasing the Co content in the magnet enhances high temperature performance. A higher Co content provides a lower temperature coefficient β of iHe. Magnets with Co content w = 0.65 have β = 0.26%C from 25°C to 300°C. Magnets with w = 0.82 have β = 0.116%C from 25°C to 300°C. The lower β results in a higher (BH)max at high temperature, and a higher TM. The TM is 240°C for w = 0.65,330°C for w = 0.68, 400°C for w = 0.76, 490°C for w = 0.78, and 550°C for w = 0.82. By increasing the Co content and adjusting the content of other elements, along with appropriate changes of processing parameters, a new series of magnets has been developed for use at temperatures from 400°C to 550°C. Magnetic properties vs. temperature for the new series of magnets, in comparison to those of the best commercial magnets, are shown in this paper to illustrate the improvements which have been made. Magnetic properties at different temperatures vs. Co content for the series are also reported in this paper.
Human heart rate monitors (HRMs) are frequently used in equine studies to measure heart rate (HR) and interbeat intervals (IBIs). However, to date, the most commonly used HRM (the Polar® system) in horses has not been validated against simultaneously recorded electrocardiogram (ECG) signals during a range of ambulatory conditions. Polar® S810i and ECG IBIs were simultaneously recorded from six horses under three conditions commonly included in behavioural observation: standing at rest, loose in the stable and at liberty in a field. Following recording, Polar® IBI data were corrected for error processing in cardiac data. Corrected and uncorrected Polar® data were then compared with simultaneously recorded ECG data using a variety of commonly measured time and frequency domain parameters (e.g. HR variability (HRV)). Polar® data collected while horses were stabled or in the field were significantly different from ECG data, even following correction of the data, and therefore, it may not be possible for the two systems to be used interchangeably. This study indicates the need for caution while using Polar® S810i for collecting HRV data, unless horses are stationary, and even when the IBI data are corrected for measurement error.
Studies investigating the role of oxidative stress in both the ageing process and osteoarthritis (OA) in human beings are limited by the unavailability of samples from healthy subjects. OA occurs naturally in the horse and has been used as a model of human OA. The objective of this study was to determine the effect of ageing and OA on the non-enzymatic synovial fluid antioxidant status of the horse. The concentrations of ascorbic acid, dehydroascorbate (DHA, oxidized ascorbic acid), uric acid, glutathione, α-tocopherol and thiobarbituric acid reactive substances (TBARS) were determined in paired synovial fluid and plasma samples from 25 horses aged between 3 and 25 years. Osteoarthritic lesions were scored from 0 (healthy) to 4 (severe OA). Glutathione was not detectable in synovial fluid. Neither plasma nor synovial fluid antioxidant concentrations were affected by age. Ascorbic acid concentrations in plasma correlated strongly with those in synovial fluid from both healthy (P < 0.001) and diseased joints (P = 0.003). Synovial fluid concentrations of ascorbic acid and uric acid were not influenced by OA compared with healthy joints. However, the concentration of DHA was slightly, but significantly, elevated in synovial fluid from joints with severe OA (95% CI: [2.2, 11.8] μmol l− 1; P < 0.001). OA is associated with only a mild oxidative burden, which does not appear to overwhelm the synovial fluid antioxidant capacity. Consequently, antioxidant supplementation is unlikely to have a beneficial effect in the treatment of OA.
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.
Few studies exist regarding the physiological responses of equestrian riders during actual or simulated competition. Interest has proliferated in recent years on the responses of riders, which is mainly due to the fatal tragedies that occurred in eventing in the late 1990s. More emphasis is also being placed on the importance of riders, fitness in order to improve athletic performance at the international level. The aim of the present study was to investigate the fitness and exercise capacity of female equestrian athletes, and to relate this to the metabolic requirements of dressage (DR), showjumping (SJ) and cross-country (XC) phases of the one-day event. Sixteen female collegiate riders (age = 24.5 ± 7.7 years; height = 166.6 ± 3.8 cm; weight = 60.4 ± 6.0 kg) competed in a simulated Horse Trials Pre-Novice competition riding either their own horse or one familiar to them. Anthropometric data were obtained for each rider (body mass index (BMI) = 21.7 ± 1.9; % body fat (BF) = 23.4 ± 5.3; lean body mass (LBM) = 48.5 ± 3.6). Each subject successfully completed all three phases of the event. There was a progressive increase in oxygen consumption (VO2) during the three phases (DR, SJ and XC) from a mean value of 20.4 ± 4.0 ml kg− 1 min− 1 (DR), 28.1 ± 4.2 ml kg− 1 min− 1 (SJ) to 31.2 ± 6.6 ml kg− 1 min− 1 (XC) (P < 0.001). Heart rate data showed a similar trend from a mean value of 157 ± 15 beats min− 1 (DR), 180 ± 11 beats min− 1 (SJ) to 184 ± 11 beats min− 1 (XC) (P < 0.001). Mean lactate concentration increased progressively from resting values: rest 2.5 ± 1.3 mmol, DR 4.8 ± 1.8 mmol, SJ 7.8 ± 2.4 mmol and XC 9.5 ± 2.7 mmol (P < 0.001). Urine osmolality was significantly (P < 0.001) increased from a pre-competition mean of 0.488 ± 0.270 mOsmol l− 1 to a post-competition mean of 0.684 ± 0.230 mOsmol l− 1. Mean hand grip strength was observed to decrease significantly (P < 0.01) from a pre-value of 32.3 ± 6.3 kg to a post-value of 29.8 ± 5.5 kg. Mean weight loss pre- to post-competition was 1.6 ± 1.1% body weight (P < 0.01). In conclusion, the study emphasises the variability in metabolic cost between riders performing in the same simulated competition but riding different horses, and highlights the difference in metabolic demand between the different phases.
An understanding of the physiological and metabolic demands of competition is essential for the development of training regimens that elicit adaptations appropriate for the sport being participated in. Despite the fact that dressage is a major sport and one of only three equestrian Olympic disciplines, to date there appear to be no studies that have described the heart rate of horses performing competitive dressage in any detail. The present study was therefore undertaken to describe the physiological demands of dressage competition. Thirty-five horses competing in a total of 50 dressage tests, 36 of which were at British dressage (BD) elementary level and 14 at BD medium level, were studied. The horses studied were predominantly Warmblood or Thoroughbred cross geldings with an age range from 6 to 17 (mean ± SD age of 10.0 ± 2.5 years). The average durations of warm-up for all horses competing were 31.3 ± 15.4 min at elementary level (n = 36) and 31.4 ± 10.0 min at medium level (n = 14; P>0.05). The mean and mean peak heart rates for horses warming up for elementary level were 91 ± 13 and 146 ± 35 bpm (beats min− 1), respectively, and were not different to that for horses warming up for medium level (mean 91 ± 10 bpm; peak: 144 ± 32 bpm; P>0.05). The mean and mean peak heart rates for all horses while competing at elementary level (n = 36) were 102 ± 13 and 132 ± 20 bpm, respectively, and 107 ± 8 and 132 ± 10 bpm, respectively, for medium level (n = 14), and were not significantly different (P>0.05). Mean heart rates during competition were significantly higher compared with that during warm-up for both elementary and medium levels (P < 0.001). Mean heart rate during competition (elementary and medium data combined) was significantly correlated with mean heart rate during warm-up (r2 = 0.503; n = 50; P < 0.001). There was no association between heart rate, warm-up duration and score or placing. These observations suggest that competitive dressage at BD elementary and medium levels is only moderately aerobically demanding.
A fable is a narrative episode (resulting in a moral), in which animals usually appear with the mental faculties of human beings but with their own physical characteristics. At times, humans are present with or without animals. This type of literature was particularly developed among the Greeks. Many of the most ancient fables have continued to be popular, in unbroken line, till the present day, including in animal epics. The earliest known fabulist was Aesop, a slave from the Island of Samos in the sixth century B.C., according to the testimony of Herodotus (II, 134). (The editors.)
Poems that present themselves as being self-interpreting offer a unique challenge: does the reader take a poem's allegory of its own narrative as the authoritative reading, or treat the moral's mechanism as a device that supports or strains against the rest of the poem as part of a literary aim? In our age works like Stoppard's The Real Inspector Hound or Nabokov's Pale Fire deploy mock commentary for the sake of interrogating the critical enterprise, and that artistic strategy might prove beneficial when examining certain medieval works. Rita Copeland argues that scholastic commentary appended to classical works has the function of usurping textual authority “by reconstituting the argumentative structure of the text.” While this claim holds true for Christian allegorizations of pagan narratives, one must ask whether such a principle holds equally true for works where the poet himself has written the commentary. Next, one should question whether it is the poem carrying the interpretive authority or whether that mechanism is but one piece of an integrated work of art, one piece of the puzzle the poet asks the reader to assemble.
Pests compete with humans for food, fiber and shelter and may be found within a broad assemblage of organisms that includes insects, plant pathogens and weeds. Some insect pests serve as vectors of diseases caused by bacteria, filarial nematodes, protozoans and viruses. Densities of many pests are regulated by density-independent factors, particularly under fluctuating environmental extremes (e.g. temperature, precipitation). Biotic components within a pest's life system also may serve as important population regulation factors, such as interactions with predators and parasitoids. Some ecologists have theorized that competition (interspecific and/or intraspecific) for resources ultimately limits the densities and distributions of organisms, including those that are anthropocentrically categorized as pests.
Humans have been in direct competition with a myriad of pests from our ancestral beginnings. Competition with pests for food intensified when humans began to cultivate plants and domesticate animals at the beginnings of agriculture, 10 000 to 16 000 years ago (Perkins, 2002; Thacker, 2002; Bird, 2003). As humans became more competent in producing crops used for food and fiber, human densities began to increase and were organized in larger groupings such as villages. This increased concentration of humans in close proximity to their livestock is believed to have facilitated the mutation and spread of diseases across species in some instances. The earliest attempts at agricultural pest control were likely very direct and included handpicking and crushing insects, pulling or cutting weeds and discarding rotting food sources.
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.
While there have been several studies of heart rates (HRs) of horses during exercise in water, the effect of exercise in water of different temperatures has not been reported. While the increase in HR during exercise is primarily related to the intensity of exercise and therefore metabolic rate, increasing body temperature can also contribute to elevations in HR separate to muscle metabolic activity per se. When exercising in water, as the thermal conductivity is greater than that of air, the temperature of the water can have a marked influence on body temperature and heat exchange compared with exercise in air. The aim of the present study was to investigate the effect of water temperature on HR of horses walking for 16 min on a water treadmill in water up to the height of the scapulohumeral joint. Eight horses were studied in three separate exercise tests in water at 13, 16 and 19°C in a randomised order in an ambient temperature between 4 and 10°C. HR was recorded continuously throughout exercise. Mean HR over the 16 min exercise period was the lowest in 13°C water (79 ± 6 bpm), intermediate in 16°C water (89 ± 7 bpm) and the highest in 19°C water (92 ± 5 bpm). A one-way ANOVA and post hoc least significant difference test comparing mean HRs at each temperature showed that there was a significant difference between HRs in water at 13 and 16°C (P < 0.0001) and in water at 13 and 19°C (P < 0.0001), but not between water at 16 and 19°C (P>0.05). Individual HRs for horses during the first minute of exercise in water of 13°C were significantly different from those in water at 16°C (P < 0.0001) and 19°C (P < 0.0001). The gradients of the log HR–time relationships showed a significant difference between exercise in the latter part of exercise in 19°C when compared with 13°C (t = 34.0, P < 0.05) and 16°C (t = 67.4, P < 0.05), suggesting that cardiovascular drift is likely when exercising in temperatures of 19°C and above. In conclusion, to the best of our knowledge, this is the first study to describe the effect of water temperature in the range of 13–19°C on the HR of horses during water treadmill exercise. Further studies to investigate the effect of different water depth and temperature combinations are indicated.
An act of government, in this case the State of California, is the driving force behind the research topic addressed in this chapter. The use of RFID to establish an ePedigree in the pharmaceutical supply chain brings to a head basic RFID frequency and technology choices that are available from vendors today. This chapter describes how the RFID Center of Excellence at the University of Pittsburgh works with pharmacy distribution and retail as they evaluate different requirements specific to the healthcare life sciences industry.
Different RFID reader environments and the physics of RFID that impact systems performance, including fundamentals of orientation, are characterized in order to explain different findings from pharmaceutical industry HF RFID pilots and from fast-moving consumer goods retail UHF RFID implementations. Alternatives of HF and UHF, namely near-field and far-field RFID options, are explored (the analogy is to compare an RF environment that is like “a prisoner in a cell” with an RF environment like “a bird in the sky”), and performance models are presented and evaluated with respect to constricted orientation and distance in real-world scenarios. A systematic layered approach for analyzing RFID interrogator-to-tag RF protocols is proposed, an insight that, should it be adopted by reader manufacturers, would dramatically improve RFID reader interoperability and testing. Recommendations are made with respect to modeling RFID systems performance and where pilots can help prepare the way for full implementation of RFID systems.
Feeding regimens for horses are usually based on perceived workload (PW) together with body condition. This can lead to inappropriate energy intake and, in particular, excess weight. Therefore, a more detailed understanding of the factors influencing individual energy needs under practical field conditions would be valuable. The purpose of this study was to evaluate to what extent the variations in actual versus PW may influence the estimated energy intake required to maintain body weight (BW) in individual animals. Eight mature, experienced riding school horses, chosen at random and maintaining a constant BW, were observed in standard flat work lessons with four different instructors at an equine training college. Heart rate (HR) and the structure of the lessons were recorded. Relative workload (RW) was determined for each horse by dividing its average HR per lesson by its estimated maximum HR (HRmax). PW was estimated by each instructor for each horse using a scale of 1–5. One-way ANOVA and t-test were used to determine the differences and Spearman's and Pearson's correlations were used to determine the correlations. The mean estimated RW was 39.1% of the estimated HRmax ( ± 5.7%) and was not significantly different between instructors (P>0.05). Rider weight as a percentage of BW showed a weak but statistically significant positive correlation with mean HR (r2 = 0.14, P < 0.05). Estimated energy intake was negatively correlated with BCS (r2 = 0.65, P < 0.001) and differed significantly (P < 0.05) between light (BW = 455–532 kg) horses (mean 0.18 ± 0.04 MJ kg− 1 BW) and heavy (BW = 622–660 kg) horses (mean 0.15 ± 0.03 MJ kg− 1 BW). No difference was found in estimated energy intake between different workloads (flat work only or flat work and jumping) (P>0.05). When BW was compared with estimated energy intake, no relation was found either (P>0.05). These results suggest that the amount of energy needed to maintain BW in individual horses cannot necessarily be estimated simply on the basis of the intensity and the duration of structured exercise. Other factors including age, individual digestive and metabolic efficiency, body condition and possibly the energy utilized through non-structured activity (e.g. box walking) may need to be taken into account.
Regular monitoring of the heart rate (HR):speed relationship may help evaluate response to training and aid in the early detection of problems. This relationship is normally determined using a treadmill or via a ridden test conducted outside on a track. Simple practical alternative methods to obtain this relationship without access to a treadmill or a track could be of value in the field. To evaluate whether the HR:speed relationship could be determined via an indoor ridden test or a lunge test, HR was monitored on two occasions at least 3 h apart, in 12 adult horses (mixed breed) in a familiar environment during a 5 or 7 m radius circle lunge (unridden) test (5LT or 7LT) and an incremental (ridden) test (RT) on the same day. The RT comprised two ridden laps of the perimeter of a 60 × 40 m indoor school at walk, three laps at trot, three at medium canter and four at fast canter (all on the right rein). The speed of each lap was recorded. The LT comprised lunging for 2 min on each rein at walk, trot and canter. Speed was determined from the number of laps completed and measurement of the distance travelled. HR and speed were highly correlated in both lunge and ridden tests (both r = 0.99 ± 0.01). V140 on the ridden test (5.2 ± 0.6 m s− 1) was significantly greater than on the pooled lunge test data (4.4 ± 0.6; P < 0.0001). There was a negative correlation between recovery HR at 2 min following either the LT or RT and V140 (P < 0.05). The slope of the HR versus speed relationship and V140 were not different between RT and 7LT, but were significantly different from those of the 5LT (P < 0.05). V140 was always lower on the lunge tests compared with the ridden test. This suggests that, in this study, lunging without a rider increased the metabolic demand above that for being ridden at a similar speed. V140 determined by the 7LT gave the closest approximation to the V140 determined by the RT. The HR:speed relationship can be obtained either from riding an incremental test in an indoor school or from an unridden lunge test.
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.