30mpw? That's pitiful. You're barely running. Most of your runs are just a warm up distance. I started running at age 28 for a 2 minute 5K. 6'4" 177lb. After 3 years I run a 16:20. Some people are faster than others with no training but they can stall. Some people have horrible cardio systems that are like dormant powerful volcanoes waiting to errupt. Get out there and run some miles for god sake! I can't believe you've been running 3 years and still on 35 a week, why? Do you not enjoy running? When it's a gorgeous day outside in summer you don't kick yourself that you can't run today because you're recovering from running too much on all the other beautiful days?
When I started I did it all wrong. I ran hard all the time and my legs were always aching, especially my calves. I had no idea running slower would help me get faster. Your body has a set amount of energy to use for running, you can blow it all out and run fast for a short period and develop speed/speed endurance (maybe you can lead a 5K for 500meters this way) OR you can conserve that energy to run longer so you're using it to build your aerobic engine. Hell it only takes 4 weeks to develop your speed. It takes years to develop your aerobic potential.
You don't need speedwork, if you ran your 30 second 200m for 5000m you would finish in 12:30! So why try and run faster? Your problem is holding a pace so you do not lack speed/strength you lack endurance. Not a surprise on 30mpw.
I went sub 20 after running 25mpw for 4 weeks and 30mpw for 4 weeks. Once I hit sub 20 I was recovering way faster. The only good run I had before 40mpw was my Saturday long run because you need to run more than 3 miles just to get warmed up and in motion. Once I was running longer runs everyday I noticed my form changed after 4 miles, I became relaxed and it just felt right. This gives the brain more neurological experience from practice when you sleep at night and recover. When I was running just 3 mile runs it seemed like a long distance. Now when I run a long run and I have 3 miles left I smash the gears up because it's such a short distance mentally now I do way longer runs.
Here's my tip if you want to get fast and win some local races then don't get injured.
Build a base, develop your aerobic capacity by running everyday for long distances at easy paces. Your aerobic capacity is limitless but your basic speed is limited to your natural talent and it only takes 4 weeks to develop it. Plus most races are 95% endurance and 5% anaerobic.
There's no point in running fast until your aerobic capacity is built, this is done with long slow runs, train don't strain. Try and be consistent running at least 6 days a week, the more consistent you are the less niggles you will get. Once you reach high mileage you will have developed a very efficient good running form, strength and aerobic conditioning.
Here's a good mileage build up plan once you hit 25mpw. It has built in safety valves to prevent injury.
Four Week Block1 - 25, 17, 25, 12.5 miles
Four Week Block 2 - 30, 21, 30, 15 miles
Four Week Block 3 - 40, 28, 40, 20 miles
Four Week Block 4 - 45, 31, 45, 22.5 miles
Four Week Block 5 - 50, 35, 50, 35 miles
Four Week Block 6 - 55, 38, 55, 27.5 miles
Four Week Block 7 - 60, 42, 60, 30 miles
Four Week Block 8 - 65, 45, 65, 32.5 miles
Four Week Block 9 - 70, 49, 70, 35 miles
Four Week Block 10 - 75, 50, 75, 37.5 miles
Four Week Block 11 - 80, 56, 80, 40 miles
Four Week Block 12 - 85, 60, 85, 42.5 miles
Four Week Block 13 - 90, 62, 90, 45 miles
Four Week Block 14 - 95, 66, 95, 47.5 miles
Four Week Block 15 - 100, 70, 100, 50 miles
Long runs, start with 6 miles then increase one mile a week until you reach 10 miles. Then increase 2 miles every 2 weeks until you reach 18 miles, if you want to reach 30 mile long rules, continue to with long run build up...take time off as needed.
The Easy-Week Rule. If you cut your mileage by 30% the second week and 50% the fourth week, you can avoid build up stress. This is a safety valve which allows your body to recover and shake off the accumulate stress.
The second important rest concept is that it takes about 21 days for muscles to adapt to the stress when you move into a new and more challenging training program. After about 11 days your'll feel stronger when the muscles have adapted to about half the stress. There is a strong temptation then to think your're ready to increase the stress again, but the body is not quite ready. After three weeks, the body has theoretically adapted and is ready for a new stress load.
You want to finish every run with room left in the tank. After a few months you will notice your easy pace will get faster and faster without forcing it.
Last tip is try and eat a lot of fruit after a run within 2 hours because your body can uptake 8 times as much sugar after exercising. Your muscles will be screaming for sugar after a workout and starch/meat/dairy/vegetables just sit and burn in the stomach but fruit skips digestion it goes straight to absorption thanks to the simple sugars that don't need breaking down. Look at Yohan Blake he eats 16 ripe bananas a day to restore potassium and Bolt says fruit everytime. Get in as many calories as you can from ripe fruits like bananas, dates, mangos etc and at least 500ml of water for best recovery. Fat blocks bloodflow and peak power is all about bloodflow. The antioxidants in fruit speed up recovery.