Degenerative joint diseases, such as osteoarthritis, adversely impact the health of the equine athlete as well as the economics of the equine industry. Our understanding of the aetiology of osteoarthritis, although not nearly exhaustive, has increased substantially in recent years. Molecules, including cytokines, inflammatory mediators, and metalloproteinases, have been identified and associated with the progression of joint disease. Several factors, including trauma to the joint, immobilization, conformation, shoeing, and ageing, have been linked with osteoarthritis. Our continued efforts into elucidating critical biological mediators and risk factors, coupled with better chondroprotective therapies and diagnostic tools, should facilitate our ability to maintain the skeletal health of the equine athlete

The impact of stress fractures on competitive event horses in the UK is completely unknown. Ninety-one replies to 450 questionnaires sent to competitive event riders across the UK indicated that 11 horses, representing 12% of the responders, had a confirmed stress fracture. As data on the total number of horses owned or ridden by the riders were not available, the true prevalence of stress fractures in this sample of horses could not be directly assessed. Within the bounds of this study, competitive level of the rider had a significant effect on stress fracture prevalence (X2(0.05, df. 2) = 24.74, P<0.05), as did years of eventing experience (X2(0.05, df. 1) = 27.80, P<0.01). Training regime was also influential (X2(0.05,df. 1) = 26.30, PX20.01). There was a predominance of fractures in geldings (X2(0.05, df. 1) = 24.45, P<0.03); however, geldings constituted 82% of reported cases. Thoroughbred cross horses had a significantly lower incidence of stress fractures than Thoroughbreds (X2(0.05, df. 1) = 20.82, P<0.01) but constituted only 18% of the sample. Horses in the oldest age category (9–12 years) had 6% of all stress fractures (X2(0.05, df. 2) = 24.54, P<0.1). All fractures occurred on the foreleg at the knee or below, with no significant effect of anatomical location. Seventy-three per cent of horses were not competing when diagnosed (X2(0.05, df. 1) = 22.27, P<0.1). These data indicate that useful preliminary data were yielded by the questionnaire and that further research with a larger sample size is justified.

The purpose of this study was to demonstrate whether acute vascular occlusion was safe and if it would result in changes to limb muscle size in horses. Six healthy, unfit Standardbred mares were used. Horses (standing at rest) wore an occlusion cuff at the most proximal position of the left forelimb. The right forelimb was used as control. An occlusion pressure of 200 mmHg was set for 5 min followed by a 2 min recovery. Three sets of occlusions were given to each horse. Muscle thickness was measured using B-mode ultrasound. The circumference of the forelimb and first phalanx was measured using a flexible tape measure. Pulsed-wave Doppler was performed on the radialis artery with a 5–10 MHz mechanical transducer at baseline and at each occlusion. Peak flow velocity (PFV) and the flow velocity integral (FVI) were measured each time. Mid-forelimb, but not first phalanx, girth was increased (P<0.05) in the occluded but not in the control leg following occlusion. Extensor and flexor muscle thickness was increased (P<0.05) in the occluded but not in the control leg. There were no changes (P>0.05) in PFV or FVI at any measurement time point. Acute vascular occlusion may be a suitable and safe model for studying muscle hypertrophy in horses.

Training and competing at elite as well as sub-elite level requires an optimal functioning of the body. This review looks at the case of the Kenyan runners, who consume a relatively high-quality diet based on vegetable sources with maize and kidney beans as the staple foods. The diet is high in carbohydrate and total protein, but low to borderline in a few essential amino acids. The timing of diet intake – immediately after training sessions – is optimal for skeletal muscle glycogen resynthesis that is enhanced without the help of insulin up to 60 min after cessation of exercise. Whether the total energy intake of the Kenyan runners is adequate is debatable. However, chronic undernutrition is not possible for athletes who engage in daily high-quality and -quantity physical exercise throughout most of the year. It is suggested that Kenyan runners participate in well-controlled, laboratory studies to investigate the quality of local foods and performance, as well as possible physiological adaptation mechanisms among athletes with a high habitual energy turnover.

Genes undoubtedly play a role in the development of a successful athlete. This view has flourished on anecdotes such as the observation of a child who displays the same aptitude for a particular sport as one of their parents, or a pair of sisters who both excel in the same discipline. However, the conclusions made from this type of observation have an obvious limitation: that similar environmental factors may be just as responsible as genetic inheritance in explaining the passage and sharing of talent between family members. Here, we review briefly the salient data showing that genes do play a role in athletic performance, and although the data examining the effect of specific genes are limited, we present data examining the role of the angiotensin-converting enzyme gene in human physical performance.

Physiological studies of elite and sub-elite black South African runners show that these athletes are typically about 10–12 kg lighter than white athletes and that they are able to sustain higher exercise intensities for longer than white runners. Such superior performance is not a result of higher V O2max values and hence cannot be due to superior oxygen delivery to the active muscles during maximal exercise, as is predicted by the traditional cardiovascular/anaerobic/catastrophic models of exercise physiology. A marginally superior running economy is also unlikely to be a crucial determinant in explaining this apparent superiority. However, black athletes are able to sustain lower rectal and thigh, but higher mean skin, temperatures during exercise. Furthermore, when exercising in the heat, lighter black athletes are able to maintain higher running speeds than are larger white runners matched for running performance in cool environmental conditions. According to the contrasting theory that the body acts as a complex system during exercise, the superiority of black African athletes should be sought in an enhanced capacity to maintain homeostasis in all their inter-dependent biological systems despite running at higher relative exercise intensities and metabolic rates. In this case, any explanation for the success of East African runners will be found in the way in which their innate physiology, training, environment, expectations and genes influence the function of those parts of their subconscious (and conscious) brains that appear to regulate the protection of homeostasis during exercise as part of an integrative, complex biological system.

East African athletes now dominate international distance running events from the 800 m to the marathon. Explanations for their phenomenal success have included optimal environmental conditions for developing distance running performance, psychological advantage and advantageous physiological characteristics. It is well established that genetics plays a role in determining inter-individual differences in exercise performance and adaptation to training stimuli. It is not known, however, to what extent inter-population differences (i.e. between ‘races’ and/or ethnic groups) in exercise performance can be attributed to genetics. There have been considerations that ‘black’ athletes are genetically adapted towards performance, given the concurrent success of athletes of West African ancestry in sprint events. However, the current notion of ‘race’ is not universally accepted, and genetic differences within and between populations are not clearly delineated by geographical or ethnic categorizations. Recent findings from mitochondrial DNA show that the populations from which Ethiopian athletes are drawn have not been isolated populations and are not genetically distinct from other Ethiopians. Y-chromosome analysis of the same population shows concurrent results, although some differences are present between athletes and the general Ethiopian population, suggesting an influence of the Y chromosome on athlete status in Ethiopia. It is concluded that there may be a role for genetics in the success of East African athletes; however, any genetic component to their success is unlikely to be limited to East Africans and is more likely to be found in other populations. At present it is unjustified to implicate a role for genetics in the success of East African runners when no genes have been identified as being important to their performance.

Scientific investigation of racial athletic aptitude has been preceded by a century of pseudo- and quasi-scientific speculations on this topic. For this reason, physiological and anatomical research on African runners is performed in a social context that is still permeated by folkloric ideas about racial differences, some of which pertain to athletic performance. A powerful stereotype of ‘tropical nature’ and its ‘superabundant’ vitality has influenced non-African thinking about African athletic potential. The idea that evolutionary adaptation in Africa is a particularly severe version of natural selection has had a similar effect on Western thinking about African runners. Romantic ideas about African athletic aptitude may, therefore, be understood as modern versions of the doctrine of black ‘hardiness’ that survives in contemporary biomedicine in various forms.

Kenyan runners, and especially those originating from the Kalenjin tribe, have dominated international middle- and long-distance running for over 40 years, prompting significant interest in the factors contributing to their success. Proposed explanations have included environmental factors, psychological advantage and favourable physiological characteristics, which may be genetically conferred or environmentally determined. Running is inherent within local Kenyan tradition and culture, and the Kenyan way of life, which involves many outdoor activities and pastimes in addition to mostly unfavourable living conditions, is conducive to enhanced distance running performance. Despite economic deprivation, Kenya has produced world and international running champions repeatedly over the past few decades; these champions have become role models for the younger generations, who take up running in the hope of a better future for themselves. Favourable environmental conditions such as altitude, diet and anthropometry, in addition to the motivational and socio-economic factors mentioned above, have all been proposed as possible reasons for the unsurpassed achievements of Kenyan distance runners. However, the fact that the majority of internationally successful runners originate from a small tribe that accounts for approximately 3% of the total Kenyan population also points to a possible genetic component. Whether this is subject to influence from other co-factors, such as altitude or training effects acquired during childhood, remains as yet unresolved.