The competitive power of a horse basically depends on two factors, its physiology and its condition.

Physiology consists of two broad phases. The first is characterised by growth and maturity, and the second by degeneration and ageing. In phase 1, juvenile horses sometimes mix their form dramatically, but as a horse matures, its competitive power tends to rise to a level where its performances are relatively consistent. In phase 2, general competitive power gradually diminishes with age, and the horse's performances tend to become less consistent. During this phase, horses find it more difficult to hold their form for many runs.

Condition - a horse's fitness, health and general well being - varies in relation to its different physiological stages. When a progressive juvenile is in top condition, it can improve sharply on what it has done before, and as it grows, and if its condition remains good, it can improve from race to race. A horse that is fully mature and in top condition will race consistently and perform at the best level it is capable of. When a horse is ageing and physically degenerating, its will become prone to disappointing and inconsistent performances.

Form generally runs in cycles that differ from horse to horse, usually in correlation with their constitution, or physical and mental make-up. Some horses can hold form for a long time, while others can hold it for only one or two runs. The first group give relatively more consistent performances while the second group can appear inconsistent. However, good trainers can space the runs of horses in the second group so that they race only at the top of their form cycle.

Many factors can affect a horse's condition, including its physiological state, or changes in climate, environment, training or feeding methods. When both internal and external factors are favourable, it tends to perform consistently, and vice versa. However, consistency also hinges on psychological factors such as determination, courage, competitive spirit, loyalty and temperament.

From a punter's standpoint, consistent racehorses are more reliable to bet on. We can make judgements on the consistency of an individual horse by considering the above perspectives - the more positive points we can sum up for a particular runner, the more reliable it is likely to be. However, we should not forget the proverb that says: "things always reverse themselves after reaching an extreme". Forecasting when horses that have been racing well are likely to drop in form is difficult, but we should be wary of those that have performed at their highest level in recent starts.