I've seen countless people come into the gym and throw dumbbells around like potato sacks.Many people fail to realise that they already train their arms multiple times per week, without ever doing any direct arm work. Every time we do a pressing movement, we use our triceps. Every time we pull, we use our biceps and forearms. Because our biceps and triceps get a lot of work during compound movements, it's important to limit the number of sets during isolation work. ~ Berceste