There are various mechanical methods of running / galloping along the ground and various physiological developments that can aid this. I was wondering how some of nature’s speed merchants achieve their top speed.
As many an athletics coach will tell you, there are two variables concerned with running quickly – the rate at which one can repeat a stride and the length of that stride. We can represent this by the equation below:
Stride Frequency x Stride Length = Speed
There are many adaptations that have evolved to enable animals to run faster, be they the hunter or the hunted. Let’s briefly consider some of the more significant ones.
– longer legs allows for a longer stride but requires more co-ordination & effort to control & maintain
– quadruped vs biped, being quadrupedal has many advantages, including longer stride length, shared muscle effort, potential spinal flexibility in gait
– increased number of pivot points; running on toes, extension of shoulder in gait – these adaptations can both increase stride length & increase the number of muscle groups that can add to the effort
– how close to the joint a muscle is connected to the bone, varies the offset between power & rate of stride
– muscle structure; all muscle fibres are not the same, a greater proportion of fast twitch fibres allows for more rapid contraction & repetition of a muscle
– alimentary canal structure & position; the more energy dense diet of a carnivore, allows for a smaller, simpler gut which in turn can be positioned in a less hindersome point of the body cavity
– advanced mitochondrial function that enable a greater & more rapid release of ATP to power the muscle contractions
|Species||Stride Freq||Stride Length||Theoretical Speed||Theoretical Speed||Reputed Max Spd|
|strides / sec||metres||m/s||mph||mph|
|Horse (TB & QH)||2.5||7.5||18.75||42||50|
In the table above, I have included sample data for:
Cheetah – the supreme land speed merchant. Capable of incredible bursts of speed, if only for short distances (typically no more than 400m). This beautiful cat has it all when it comes to peak speed. Extended shoulder & limb flexion, a compact carnivore’s gut placed high & to the rear, significant back flexion, specialised muscles with unique mitochondria.
Horse – bred for speed by mankind. These equine athlete’s real stand out feature is their ability to provide much of their speed for very long durations. Figures quoted are an average between Quarter-horses and Thoroughbreds.
Dog – more specifically the Greyhound. Again bred for speed my mankind, the greyhound is the speediest of the canids. Moving in a rotary gallop, the same as a Cheetah (not the same as an equine gallop) they can achieve significant pace along with mediocre stamina.
Ostrich – fastest of all bipeds. The Ostrich can achieve horse like speed, with good stamina – helped significantly by a long 5m bipedal stride length.
Human – included here for reference. Humans are not the most efficient of runners, being more of a ‘jack of all trades’, reasonably capable of various other actions too, like climbing trees or swimming.
Credit: Much of the work on this area was carried out by Hildebrand in the late 1950s – early 1960s. Of course there have been various useful studies since then that are available to view on the internet; try searches like ‘ Animal Locomotion’ or ‘Gait of animals’.
Note. Cheetah data from captive Cheetahs has so far been unable to repeat the extremes observed in the wild, hardly surprising really.
Trivia: Did you know that a Cheetah can almost reach top speed in 3 strides, perhaps around 3 seconds. That’s a feat of acceleration to 60mph that few supercars can match.
A couple of fun & interesting video links: BBC Earth – Greyhound slomo and Bryan Habana & the Cheetah’s struggle for survival.