The Lull is Over

Last week’s I was bemoaning being in a VO2 lull and expecting it to last for 10-13 days. On day 10, I had my best run and my legs were pretty much back in action. To give you some hard data to work with let’s go through the days.

Day 0 – Saturday 6th November

All-out parkrun, full of surges and efforts takes 25 seconds off my time of two weeks before and puts me into the VO2 lull.

Day 1 – Sunday 7th November

Sunday morning long run fasted at 6:35am. Distance run is 11.7 miles in 1hr38 – 8:22/mile.  Fastest two miles are #4-5 at 8:04 / 7:38 on a downhill stretch but nothing else came in quicker than 8:14 and the 11th mile was a glycogen-depleted 8:56.  Average heart-rate was 133bpm and I could barely find the effort to get it above the low 140s.

Day 2 – Monday 8th November

30-min recovery run, fasted at 7am. Distance of 3.9 miles in 31:48 at 8:09/mile.

This wasn’t a bad run in itself but then I did some run drills after and a 40-min core session which may have tipped me over the edge. Average heart-rate similar to yesterday at 134 and only just hitting low 140s.

Day 3 – Tuesday 9th November

A 9-mile Steady run at the beach taking 1hr14 and averaging 8:10/mile.

Conditions were great for running when I set off – nice and sunny. Legs felt ok to begin with and after a half mile warmup the first mile came in at 7:29 followed by 7:34, 39, 49. But when I turned round it was a little colder and my legs faded to the extent I was running at 8:40/mile.

Heart-rate reached high 140s on the outward leg but dropped as the run went on to end up averaging 142bpm.

When I arrived back at the car I found my feet were covered in spots and blemishes, I believe it was a sweat rash.

Day 4 – Wednesday 10th November

Recovering run of 4.4 miles taking 40:39.  Average pace 9:10/mile, fastest mile 8:47; HR-avg 124 and barely able to reach 130s.

The sweat rash was still present when feet got hot and woke me in the night 3-4 times. It’s probable I’d gone into anaerobic overtraining and was over revving the Central Nervous System.

Day 5 – Thursday 11th November

Improvement over yesterday. Same route with a little extra tacked on to make it 4.7 miles in 41:02. Average pace was 8:44/mile, heart-rate only 2 beats higher at 126 but still unable to find any power to push it up beyond 135bpm. Fastest mile came in at 8:22.

Day 6 – Friday 12th November

A repeat of Tuesday’s 9-mile run. A real lowpoint. The wind was 18-20mph and the run took 1h23 – an average pace of 9:11/mile for a heart-rate average of 129.

Even with a tailwind, the outward leg got no faster than 8:06 but on the way back, into the wind, I was over 10min/mile with a trudging 10:29 mile towards the end as I could barely lift my legs. The sweat rash had all but gone now and I had a night of nearly unbroken sleep.

Day 7 – Saturday 13th November

Back to parkrun. I ran 26mins for the parkrun with my fastest mile coming in at 8:15.

Day 8 – Sunday 14th November

Standard 11.7 miles long run, fasted at 7am. At last an indication of the legs beginning to feel better. The run was three minutes quicker than last Sunday at 1hr35 and averaging 8:07/mile for a HR-average of 138bpm. Note how I couldn’t even reach this heart-rate on some of the runs earlier in the week. Fastest mile was 7:35 (downhill) with three more sub-8s thrown in.

Day 9 – Monday 15th November

Early morning, fasted run with legs beginning to feel better. Distance was 3.8 miles in 30:44 – an average of 8:04/mile with a fastest mile of 7:36. On paper very similar to last week but legs were feeling more like running.

Day 10 – Tuesday 16th November

The game changer! Legs felt great and there was an early indication as I waited for GPS to lock in. My standing heart-rate dropped quickly from 50+ beats per minute to 37-38. That’s always a sign I’m ready to run.

Once again the 9-mile route at the beach and I found my legs were propelling me forwards with each stride. Where I’d run this route in 1hr14 and 1hr23 last week, today I ran it in 1hr05 – an average of 7:11/mile. More importantly that’s an improvement of 8-secs/mile from two weeks ago before the parkrun. My heart-rate ended up averaging 152bpm for the run and peaking at 161bpm. I pushed quite hard on the run back and managed to run the last two miles at 7:15/mile each – no dropoff.

Yet while I think my legs are back, I’m not sure there isn’t a little more to come. My fastest mile was only 6:53 and the next fastest was 7:01. Two weeks ago, I ran the first two miles in 6:47 and 6:46.


So there we go – a detailed look at how I recovered from an all-out parkrun, a VO2 lull and possible anaerobic overtraining by listening to my body and letting my legs run only as fast as they were willing. I’m sure had I wanted to I could have pushed harder on some days but I’m not sure it would have done me good. Most likely it would have delayed the recovery process and possibly trigged an injury – strain or otherwise.

If you go through again you’ll see the legs generally had noting extra to give in the early days and this reflects in the low heart-rates. Low heart-rates suggest I’m burning mostly fats and less glycogen. As the fast-twitch muscles (which use glycogen and will have taken longer to repair) became available again I was able to start going faster and the heart-rates rose. When they had really regained their oomph, I found my legs were much bouncier and I was popping off the pavement with each step.

Now I’m going to take a few more easy days as I look to improve on my parkrun time on Saturday.

The VO2 lull

I’m currently going through what I term a “VO2 lull”. It’s something I’ve encountered across my running years but taken a long time to understand, and even longer to recognise when it’s happening. Last Saturday I ran a good, hard parkrun at Upton House. Combining efforts up the hills with surges to try and catch runners ahead of me, as well as bursts to stay in front of those behind me, it was an all-out effort. With fresh legs going into it, from three days of easy running, I found an extra gear whenever I needed it. While I felt fairly good immediately afterwards, my legs have had nothing all week. I’ve lost a good minute off my easy run pace and this is what I’m calling the VO2 lull.

First off I need to explain the V02 part. Exercise physiologists like putting runners on treadmills and measuring the effects of running at ever-increasing speeds. One of the key measurements they take is the amount of oxygen breathed in, as well as carbon dioxide breathed out and heart-rate. When they measure the oxygen (O2) intake and utilisation it is correctly termed V̇O2 with a little dot over the V indicating it’s a rate but most people refer to it as VO2 partly because how do you pronounce a dot? It’s partly because it’s too onerous for them to figure out how to get the dotted V̇ on a word processor!

In chapter 8 of Build Your Running Body, Pete Magill details the growth cycle of mitochondria which are fundamental to producing aerobic energy. Mitochondria are often described as the powerhouses of the cell as they convert oxygen to energy which then powers your exercise. The importance of mitochondria to any distance runner cannot be overstated enough – they are the source of your aerobic ability which itself is key to distance running success.

Magill explains that it takes 4-5 weeks for mitochondria to fully grow but there’s a problem. “When mitochondria first begin adapting, they can’t contribute to aerobic energy production … this phase lasts from ten to thirteen days and creates an “oxygen utilistation problem” … you can expect to feel sluggish doing workouts that were easy the previous week” (p.142)

That’s exactly where I’ve been this week. Last week I was running a 20:55 parkrun at 6:45/mile pace; the next day my legs could barely achieve eight minute miles on my long run. This might have been due to recovery factors but it’s continued on through the week. My Tuesday Steady run which I was running at an average of 7:20/mile last week came in at 8:10/mile this week. Wednesday’s recovery run averaged 9:10/mile; today’s, five days after parkrun, came in at 8:44/mile. My legs have got nothing – no bounce, oomph or power. I’m barely getting out of the fat-burning zone on these runs.

So I now just have to wait for the mitochondrial adaptation to take place and in the meantime, plod along. This isn’t the first time I’ve been here but this phenomena is so poorly known that, in the past, I would start to take action to try and get back ontrack. I might rest (not a bad option if it’s only a day or two), do some strides (poor option as legs are already tired), do less mileage (not great as you won’t necessarily reinforce the growth), or try to continue doing what I usually do at the usual paces (effectively overtraining which usually led to injury). When it happened to me after marathons, it usually led me to quit running for six months or more. It’s only now I realise you just have to jog until the legs splutter back into life as they eventually will. It’s quite a remarkable experience because one day running feels awful, the next it’s like you’re running on bedsprings as the adaptations finally kick in.