With the decline of the general physical conditioning of the entire population in many first world countries due to changing societal norms and fast food, so has the general physical conditioning of police officers. In order to pander to a larger less fit population, many police stations have relaxed their physical fitness standards.
Nowadays we can see skinny weak officers, fat officers, and even tiny female officers. Enforcing the law often requires the use of physical force against uncooperative civilians, and this often requires overpowering these civilians. These civilians may be under the influence, enraged, and naturally strong. It is a joke when law enforcement does not have the physical capabilities to physically restrain a suspect, and just makes them look incompetent. However, there are cops that like to obtain peak physical conditioning, and will also train in some sort of martial arts. These are the ones that will make you look like a fool if you try to resist.