were you doing curls I suppose, cause if you werent feeling sore after 5 days, than 5 days is plenty. Some very common reasons are that
1. You didnt get enough sleep either the day you worked out the first time or the night before you just worked again
2. You havent been eating properly by getting enough protein and other nutrients to actually build the muscles.
3. You didnt eat the right foods, or at the right time before you just worked out again, because trust me by not eating enough food before exercise, you wont believe the difference in initial strength and how quickly your sets will fade.
4. You are just having a bad day in which you cant get discouraged, maybe your technique was favoring making the weight easier the first time by rocking back on each curl and you did it right this time, therefore making it harder but more effective.
But whatever it is, you cant get discouraged so easily by just 2 workouts, weightlifting or training or whatever you call it, is hard work with very slow results, with some big spurts of gains. I mean I was making jumps in bench over the past few months, went form a 280 bench to to 315 bench in about a month and a half, then went back down to 305 the next week and didnt budge for about 3 weeks, then went to 325 the next 3 weeks. Your body will catch up, it just goes through phases, and if your not making gains, it is almost always you diet or your sleep.
