when I was 34 I ran my 5k's in 21's my goal was to hit 20min I took a 2 year break from Running do to working 60 hours a week, before then I wasn't working at all. Now I'm back at it, and I've been back running for almost 2 years, I'm 38 now. My 5K time is a sucking 23's that's shame!!! My LSD runs keeping BPM at 150 I'm shocked my pace is 9:30 to 10:00 I HATE THAT, before it was around 8:30. Running a 7:45 pace was so easy!! BPM was around 160 now 7:45 is like 183 and hurts...I'm trying to think back to what I was doing to be so good, but then I just ran, so I don't know what I did. I admit my speed work is lacking some, I'm not as consistent as I was then. I use to be able to run 4 x 1600 at a 6:50 pace reaching a BPM of 193 now I'm lucky to run 3x 1600 at a 7:30 pace with a BMP of 177. I run around 30 miles a week, I haven't done much hill work. I did some 800's last week of a pace of around 7:12 I think that's prob the first speed work I have done in a long time, This past winter most of my running was done on the treadmill so what do I need to do? more LSD? to get that BPM and pace better? more speed work and hills? or am I just old???? I know this women that's in her 50's and she just seems to be getting better every year. I ran a half marathon couple weeks ago and had to stop to poop along side the road at mile 11, the Jell they handed out I didn't do well with, I ran that in a time of 153:56 that was my 2nd half, first was in a time of 147 but that was 4 years ago, I have not had any weight gain, I'm fit and very thin, I don't smoke. I want my 21's even 22's would work!
I think you answered you own question, be more consistent and do at least one speed (quality) workout a week in about a month add one more. You have to run some at a pace that is not comfortable. The other way is to add more miles per week.
Here are a couple of 5K workouts I like:
2 mile warm up then : 2 miles @ a little under current 5K pace 4 mins rest then 2 X 800 a tad faster then your 2 mile pace with 2 mins of rest between, a good cooldown 1-2 miles.
2 mile warm up: Then 8 X 800 pace 3K or a little faster than current 5K pace with same recovery as your 800.
800 is 3:45 you get 3:45 rest. A good cool down.
Hills workout will also help
Be careful adding speed work, if you add to quickly over use injury may happen.
The running speed for long distance is largely determined by your fastest mile time. For instance with proper weekly mileage one should be able to run the marathon at... fastest mile time plus 2 minutes. My advice would be to go to a track and run for all you are worth for as many laps as you can. This will boost your metabolism to a new level. Fast sprints or interval training is the best way to increase your long distance speed.