Why does a horse need a grass gallop?

been asked the following question....


When a trainer works a horse on the sand and then need to take it to the grass for a grass gallop.

Why would it bring the horse on?

What does the grass gallop bring extra to the training of the horse?

Why is it that the horse would sweat more on the grass, while the sand is more thicker and harder to work on?
Why does the horse suddenly trim up after the grass gallop?

@ Hibs
We cannot work a horse as far on sand as we can on turf, due to the training tracks being heavier. Also, when working very far on heavy sand tracks, the risk of injury is increased.
With a grass gallop, more speed over further, is what is achieved. But, there are no hard and fast rules and each horse remains an individual, in terms of what works and what doesnt. That's where the Trainer's eye and experience comes in.

Exercise in the sand is the same experience you have at dunes on the beach. It all contributes to your general fitness.

The grass is a much firmer surface with everything that implies. Riders will tell you that when you take a horse out of the energy sapping sand, they become completely different. Suddenly there is speed on tap. So as fit as you can get a horse on a soft surface, on the harder surface the horse is actually able to hit 60km and red-line it for a kilometer or more. It's like having full access to empty a petrol tank in seconds, when everywhere else there are limiters.

It may seem like a small difference, but cars go from being efficient at 100kph to guzzling at 120, and can go for days at one speed and blow a gasket at a speed just a bit faster. Until you hit full speed, the rest is a sort of simulation for the real thing.

Mr G has it in one: "more speed over further"!

difference in top speed on the Summerveld turn, sand vs grass is on average 12 to 15%

There is a trainer in the UK who trains her string on walkers only,seemingly trainers like to claim her horses thinking there must be a bit left to find with them..