Different individuals have different fitness levels.
Both Kyla and Tia will be in their zone. Even if they dicrease their heart rates by 20 beats per minute from 175 beats per minute. 155 beats per minute still falls under kyla's target heart rate zone and Tia's target heart rate zone.
1. change
The natural selection is a process that occurs as a direct consequence of the living conditions in the environment. When the environment starts to change though, the organisms that live in it face a big challenge. They either have to change, adapt to the new conditions, and thus survive, or if they are not able to do so, to die out. This is the biggest evolutionary pressure for the organisms, and while some come out as winners from it, many others die out .
2. variation
In order for the process of natural selection to occur, the population needs to have some genetic variation. The environment is the ultimate push factor, but if the population doesn't have genetic variation in it, than the species will die out. The genetic variation is very important as in that way the individuals choose who will they mate with, in accordance with their traits, so that only the advantageous traits can be passed on to the next generation, so that it can be more competitive in the environment.
3. traits
The natural selection is a very simple process. The individuals of a population, when choosing a mate, look for the individuals that exhibit traits that are advantageous for survival. Mating with individuals with traits that are advantageous guarantees that the offspring will inherit those traits, thus it will have higher chances to survive. The individuals that do not have advantageous traits though will be avoided as mating partners, and that would rapidly lead to their decline and elimination from the gene pool, as they will not have any offspring to continue their line.
I think Greg needs to start small than go bigger on the excersise .
He shouldn't rush on the process and he should be careful.Take everything slow.
He should work hard but not to the point where he gets hurt again or more.
Remind him to stretch before he does
Excersising.
He should run shorter distances and than later increase the number of miles or laps he is running .
I hope I helped I am not really a athletic person though
You should have a doctor immediately evaluate the patient and follow the doctor's orders.