Luffy Gear Second

One of my all time favorite scenes in One Piece is when Luffy first uses his Gear Second technique during the Enies Lobby Arc. The beating he put on Blueno of CP9 was simply amazing and justified! As everyone should know or if you forgot or don't know, Luffy powers himself up by using the rubber element of his body as a pump to increase his blood flow, thus gaining him the ability to move at high speeds and deliver more powerful attacks. It's like an overdrive technique that pushes his body to the limit, but thanks to elasticity of his body he can maintain it using so much energy and oxygen as his body can handle for a period of time. In this overdrive state, Luffy's body heats up from the increased blood flow and turns his skin to a pinkish-red color. As he releases sweat to cool his body down it constantly vaporizes into steam. Gear Second made its debut in One Piece Chapter 387 and Anime Episode 272

Although it is said that Gear 2nd shortens Luffy's lifespan, I don't believe it to be true. I think of it as a move that shortens his stamina in a fight, yet prolongs it in the long run after his battles. Everytime Luffy uses this gear he is getting a super workout 9000 times more than the average human. Being a rubberman his muscles should have a better rate of repairing itself after this intense workout. Since his organs and everything can stretch, his heart and lungs should be able to handle the strain he puts on himself. The more Luffy uses 2nd Gear the longer he can use it without it greatly damaging his stamina. Gear Second is a go-to move for Luffy after the Enies Lobby showdown proving to be effect against most of his opponents. If Gear 2 alone can't get the job done then expect him bust out his Gear Third! After the time-skip Luffy learns Armament-Haki and fuses it with his techniques, making them much strongner and enabling damage to Logia Devil Fruit users.
Here is a list of some of his Gear Second Attacks. ( basically his normal attacks upgraded )

•  Jet Pistol
• Jet Gatling Gun
• Jet Whip
• Jet Spear
• Jet Bazooka
• Jet Stamp
• Jet Bullet
• Jet Axe
• Jet Rocket
• Jet Rifle

With Haki

• Red Hawk
• Hawk Bullet
• Hawk Rifle
• Hawk Gatling
• Eagle Bazooka