Is it possible to reliably define the times (for a specific location on earth) when the tidal gravity from astronomical objects (moon, sun etc.) are at their weakest & strongest?

I have considered using sea & ocean tide times, but these factor in unwanted variables, such as ocean currents and coastal water flows, which would invalidate the results somewhat.

I am attempting to define whether any noticeable effects occur from the moon on athletic performance, but need specific times with which to test and compare (hence the strongest & weakest times are my targets).

Is there a reliable method to calculate the times of strongest and weakest gravitational pull of the moon upon objects at a specific location on earth, in effect a high and low tide? We considered using tide times, but they factor in variables such as ocean currents and coastal flows, which would adversly affect our results. Is there a formula that can give us a good answer?

Is there a formula to give the times when the lunar gravitational effects are strongest and weakest for a location on earth? We considered the tide times, but they factor in variables such as coastal flows and ocean currents, which would adversly alter the calculations

I have a theory that may work in conjunction with popular belief that dinosaurs were wiped out by meteor impact. Given the size of animal and plant life during the time and to some the seemingly laughable proportions ie huge bodies and small legs arms of some creatures. If gravitational strength was lower those creatures would not need strength in proportion to body mass or wieght.  Plants would/could grow larger taller without the confines of gravity as we know it. Could it also explain the seemingly impossible feats of strenth we debate over regarding placement of objects and the building of structures by our human ancestors. Scientists research and tell us of THE meteor impact that wiped out the dinosaurs. Could it be that over a period of time there was more than a couple of impacts that we can no longer find evidence of and that, and by changing the density and mass of the earth we now experience gravity at a higher strength. We know that physically we adapt ie loss of hair due to temperature change, creatures in caves being blind etc.      

Is gravity some kind of pure energy? If yes, how does it affect the world around it in such a large way? If no, how it is "transported" around the universe?

After arguing about it for an hour or so, a friend and I are confused about what would happen if you were in the centre of the earth.

That is, you were in a spherical chasm in the exact centre of the earth, and the earth was a perfect sphere.  Ignoring the heat and lack of oxygen, what would the gravity of the earth do?  Pull you apart, crush you, or nothing?

disregarding the heat etc would gravity hold the object suspended at the centre of the earth

My son asked this question which I can't answer!  Assume that the hole goes right through, i.e. no core.

Aside from bone and muscle differences, which have already been covered.

For example, someone who grows up without being spun around at 400m/s as the world spins; would they feel as if they were spinning when they set down or entered orbit?