Several "body related skills" could be implemented as a single skill, with multiple perk routes depending on what was important to you. Climbing, running, jumping, swimming, with various perks in each tree branch. I have a hard time coming up with a good fully working skill perk tree for all of these as single skills.
The mod I will never finish includes the following "Athletics" skill tree. Note that climbing is a minigame-like event that occurs on select surfaces designated for this purpose. It plays a similar role to lockpicking, allowing you to skip parts of dungeons and access special locations. The minigame involves planning a route from the bottom to the top of the surface by moving from one handhold to another without running out of stamina or falling.
I'm actually really proud of the constellation design, it forms a running guy. The perks below are gouped by "branch".
Athletics
Each point in this skill decreases the rate at which sprinting, power attacks, gymnastics, and grabbing handholds use stamina by .5% (-50% at level 100)
Level 0-
Conditioning: You run 10/15/20/25/30% faster and jump 10/15/20/25/30% higher (Improves at 20, 40, 60, 80)
Level 30-
Acrobatics (prereq: Conditioning): You ignore 50/75/90% of fall damage (Improves at 60, 90)
Level 50-
Gymnast (prereq: Acrobatics): You can perform a flip mind-air (a sort of "double jump"), or tumble on the ground, at the cost of stamina. You can also make melee attacks mid-jump.
Level 70-
Agile Assault (prereq: Gymnast): You gain a 20% chance of scoring a critical strike (+50% damage) after performing a mid-air flip or a tumble, and can get a special kill animation.
Level 25-
Apprentice Climber (prereq: Conditioning): You can reach handholds 25% further away without risking a fall
Level 50-
Adept Climber (prereq: Apprentice Climber): You can reach handholds 50% further away without risking a fall
Level 60-
Practiced Grip (prereq: Adept Climber): You don't automatically lose stamina while climbing, though each handhold you try for still costs the same. Rank 2 (level 80): Your stamina regenerates normally while climbing.
Level 75-
Expert Climber (prereq: Adept Climber): You can reach handholds 75% further away without risking a fall
Level 100-
Master Climber (prereq: Master Climber): You can reach handholds 100% further away without risking a fall
Level 30-
Strong Swimmer (prereq: Conditioning): You can "sprint" while swimming, and attack with melee weapons in the water.
Level 50-
Deep Diver (prereq: Natural Swimmer): You can hold your breath for five times as long.
Level 100-
Legendary Reflexes (prereq: Gymnast or Adept Climber)
You can slow down time by 25% at will (adds a on/off toggle power) but this will steadily drain your stamina.