“Hammer” is to pedal or cycle as hard and quickly as one’s body can still keep going. To become “hammered” is to be bested or left behind by one who is superior.
Hammering in cycling typically occurs in breakaways or group sprints, where cyclists ride very hard. Hammering in running is the final push or surge segment. Hammer efforts increase the body’s endurance and its adaptation to lactate. Although these effort sessions are challenging, excessive hammering leads to excessive fatigue, so you must pace yourself accordingly.