Most dogs that weigh 100 pounds plus are less athletic & shorter lived than canine middle weights & the smaller variants. This situation being similar to larger humans. In boxing, wrestling & MMA, the heavier weight classes are less efficient, resulting in less entertaining, weaker performances.
As a result of this handicap, cooling/recovery time must be carefully monitored. The challenge is the relationship of the oral cavity, the airway & the dogs ability to remain cool under stress.
The late Sugar Ray Robinson, had a trainer that could taste his sweat & determine if Robinson was physically peaking. Similar skills prove to be assets as well. For example, a conditioner (perhaps) would test the dog’s gum line & know if a dog was at risk for being over conitioned. Pinching or pulling the dogs skin is also an indicator, but less accurate. Should the skin not snap back quickly you may have an over worked dog. Watch for foot placement on the tread mill,or in an open field. Should the dogs coordination or motor skills be an issue, this too may be a negative indicator. Keep a diary with the dogs body temperature, respirations etc.
In general, dogs have a serious cooling problem. Some dogs perspire through the pores in their feet, others may not. However, this makes little difference in cooling. Nature has given us an animal that when worked hard will produce excessive heat.The dogs oral cavity, a some what limited cooling system, requires a skilled conditioner. This challenge is amplified with bigger dogs! The dogs mouth in relationship to its size & weight creates a handicap in terms of hard work.
Try to focus on pure performance & make the issue of your dogs appearance a distant second. When you & your dog score high, or win a significant event, even a butt ugly dog looks great.
If you are working a Rottweiler, Boer Boel or Corso type dog, air is far more important than power. With better wind the mastiff type dog will take longer to shed power. In fact, I would suggest 10 to 15% power trainning, the balance to be pure endurance trainning. Unless you are competing in a weight pull event, prioritize endurance ! Do not take a draft horse to the Kentucky derby. Hope my essay helps.