Experiencing Aerobic Limitation

I spent a rainy bank holiday morning sprinting up a nearby hill repeatedly. It’s a key part of getting faster and one that I’ve not done since last summer. Having woken at 6am, I grabbed a bowl of cereal then did the crossword while breakfast digested. About 8:15am, I headed out the door and there was light rain falling. The session I had in mind is not big – a 15 minute warm-up run, 5 mins of drills to help the mobility, the main session of 10 hill sprints and then a ten minute warmdown. But it is time-consuming because each sprint is followed by three minutes of recovery. In the end, it took over an hour to complete. What interested me is what the session told me about how to train for distance running.

Setting off on my warm-up it took three minutes for my body to crank the pace up and reach eight minute miling. My route is a mixture of ups and downs such that, by the end of the first mile, I’d been hitting sub-6 pace on a steeper downhill stretch – 7min38 popped up on my watch. The second mile came in at 7min04 and then I tacked on another thirty seconds back to home. What surprised me was how relatively hard I was finding it. My breathing was beginning to huff and puff like I was running a parkrun and my heart-rate reached 160bpm at the end. All in all, I was glad when I finished my warm-up and could walk back round the corner to do drills.

With the rain falling steadily and knowing I’d be standing around between the hill efforts, I elected to keep the drills short. Just one repetition of each drill taking 15 seconds and then a stride back to my start position with around 30s time to recover before the next. The stride reinforces what I’m programming as well as warming the legs up for the quicker, more violent efforts up the hill. Once again, by the end of these I was puffing and my heart-rate had steadily increased to 155bpm; each subsequent effort building the heart-rate higher than the one before.

Finally I was ready. I walked to the base of the hill and then spent a few minutes chatting with an old chap about goings on. The important thing about hill sprints is to attempt them with fresh legs so I didn’t mind an extra few minutes spent conversing. Hills sprints want to get maximum effort from the muscles which is why they only last seconds and then you get a nice long recovery. The short timeframe allows your ATP-PC energy system to be the key producer of energy while the long recovery ensures it has recharged.

The first effort I sprinted up the hill and my legs were turning over so smoothly. I was barely breathing, it was how I’d feel if I was out for a jog. Then I started to walk back down the hill and the oxygen debt kicked in and within fifteen seconds my heart-rate had reached 139bpm having started down at 90bpm. The second effort felt a little harder on the breathing especially afterwards and my heart-rate reached 143bpm. By the time I’d ambled back downhill to my starting place, it was back to 114bpm and I was feeling okay. After that my heart-rate never got out into the 140s again. Sometimes the oxygen debt after each effort resulted in very quick gasps for breath yet it didn’t take long to be back to normal. As the sprints went on they got a little slower, this is unsurprising because the muscles are beginning to fatigue and they can’t power getting as far up the hill.

After my 10th and final effort, I walked down until one minute had elapsed then began a warmdown run. My legs felt like they were springing along yet the pace was barely quicker than nine minute miling.

What intrigued me about this session was how two such different ways of training – the warm-up and sprints both taxed me in different ways. The warm-up pace picked up gradually to be a little quicker than seven minute miling where I still had room to run faster. Yet it would have been hard to stay running like this for an extended period of time. By contrast the hill sprints which are an absolute blast of maximal energy felt so much easier.

According to the wisdom of heart-rate training I could have done sprints all day long as I maxed out at whereas my warm-up reached 160bpm. Yet I know that wouldn’t be a good idea – no-one would do that, neither a sprinter or distance runner.  It highlights one of the problems of heart-rate training.

What really came home to me from the warm-up is that the thing limiting my distance running is not speed related. This is what I experienced when I first began parkrunning a decade and more ago. Every week I would run and feel there was more available in the tank yet not understand what was stopping me.

The limitation was not one of being able to run very fast for a short time as it is with anaerobic limitation, it was one of being able to run fast for a relatively long time. That’s where aerobic development is required. It took me the next five years to really begin unravelling this conundrum in detail. I read many books which talk about it needing to be done yet it’s not until you viscerally experience it that it becomes clear what is going on.

I meet many runners who haven’t yet had this realisation that being able to run fast 200s, 300s, 400s is not necessarily going to turn them into a faster distance runner. Sometimes it does but more often than not it’s about building speed through good distance training.

Maybe this is something I can help you with? Not everybody wants to be coached for a race, sometimes they simply need a training review. Understanding what they need to do next to get to the next level – is it speed or endurance they should work on. Just head over to the Contact page and give me some basic details and we can arrange a 1 hour consultation.

Update on my 800m training – Apr 2023

April has been a quiet month. Entering it I had high hopes of recording a decent time at Bournemouth Bay 1/2M but those were trashed when I ran three minutes slower than last year. I tapered better this year and my legs felt fresher on the day but, come the run it was a gradual slide with the first 2-3 miles coming in at just under seven minute miles. From mile five onwards the pace dropped to 7:25 and worse. I just had nothing and have easily done better runs in training. I documented last month how I ran six miles in 42-mins in training.

What was strange was how low my heart-rate was throughout the run. It ended up averaging 149bpm which when I consider I do Steady runs in the low 150s was very out of place. What it does go to prove is how little use a heart-rate monitor can be.

I took five days off after the half (no running at all) then went to Poole parkrun and ran 20:57. Both my calves and glutes were sore from it and I had a very slow, dreary Sunday 10-mile run. I ran thirty minutes each day through the following week and returned to Poole parkrun knocking my time down to 20:39. The following week was the same routine, a slightly faster but still drudgy ten mile run then thirty minutes each day. This resulted in a 20:17 parkrun! Three weeks of easy running, no speedwork and my racing simply got faster by forty seconds.

It now seems clear that I’d fatigued my legs too much in training. When I look back I’ve been doing fifty mile weeks since last summer and training hard in the week. The heart-rate monitor numbers were correct but the monitor itself can’t tell you how fatigued you are.

My overall feeling though is one of disillusionment – I’m simply not cut out for distance running. When I compare my training to others, I simply don’t get the results from training that they achieve off much less. I train hard with all sorts of different sessions but ultimately I’m physically not cut out for long distances.

I’ve known this for a while, it’s why I started training for the 800m. Thus far I haven’t really worked on developing my speed to a high level because I’ve been trying to keep the aerobic side in balance. As I’ve written in the Ageing series, the best male sprinters of my age are running under 11 seconds for 100m, 22s for 200m and 50s for 400m. While I’ve not gone all-out at any of these I’d be surprised if I could crack 14s for 100m, 30s for 200m or 1min15 for 400m – that’s just too far down and a gap I need to close up. It’s not because I’m not capable, it’s because I haven’t trained for it in years.

I’m beginning to conclude this has been where I’m going wrong. The first two iterations of training I followed JackD’s plan as he is a proven coach. It didn’t really help me. Last year I began hill training using a progression from Steve Magness’ The Science of Running and I felt this made a difference despite only doing one weekly session for three months.

I’m torn between entirely given up on the distance work until I’m notably nearer to the age-group records or trying to keep the two things in balance. All I know is when I started running seriously a decade ago, I was probably quicker on the speed side. I have little objective proof of this but my legs were much bigger and stronger. I was quickly able to build some of my best times at parkrun, 10K and half marathon on lower mileage than I’ve been doing recently because I had the speed first.

This summer’s plan is to repeat what I did last April / May / June. I combined Steve Magness’ hill sprints on a Monday with Jack Daniels’ 800m training plan on Wednesdays and Fridays. I lasted about nine weeks before I could see I’d peaked and my aerobic fitness was declining.

This year I’m intending to do the same but with some changes. Where I previously followed Jack’s plan for runners covering 30-40mpw, this year I’m downgrading to the 20-30mpw plan with shorter recovery and long runs. Actually Jack’s long run has always lasted only about an hour on these plans but I always did something in the 1hr30-40 range in an attempt to keep my aerobic system up.

The other change I’m going to make, as I’m not doing a time trial prior to starting training, is to be conservative on my numbers. I’m based my training level on my half marathon and fastest parkrun which basically have me running at the level of a 2:36 800m runner. It’s not that fast but I’m aiming to keep my legs fresher this year through less intensity and lower volume of training. Again this 2:36 start point is why I don’t think I’ve got the speedside sorted. It really isn’t that fast given how in shape and athletic I am. I just haven’t trained for speed enough in years.

I resumed faster training in the final week of April. I did 6x8sec hill sprints on Monday which felt great and I loved despite blowing hard at the end of each effort. On Wednesday I did 6x200m with 200m jog recovery aiming for 43s, they avg’ed 40.4sec. On Friday my legs were perking up and I repeated the session, this time with eight efforts, and they avg’ed 39.6sec. My body felt like it was hitting new territory. Or at least territory which it hasn’t been to in a long time. My breathing was gasping in the final efforts. I’ve been there before but this felt different for some inexplicable reason.

Before each of the workouts, I’ve been doing drills and strides to help warm-up and ingrain good form. I began these eighteen months ago and change has been gradual, notably beginning to kick in at the start of the year when I was doing my last block of short intervals. This explains why my glutes and calves hurt after the half marathon. It was the longest sustained effort I’ve done using that running form and therefore being powered by those muscles. My stride seems to be lengthening and when I begin an effort I can hit higher cadences than usual. This all suggests I can get quicker and build my speed up to the levels I desire.

Update on my 800m training – May 2022

Was it the hills?  I entered the month feeling positive after some very quick short intervals in April but throughout May my legs have struggled. I started doing hills in April to build speed and they’re certainly feeling stronger but they also tend to take a few days to fully recover.

I’ve never been a decent sprinter but I think I probably should have been. Firstly because I find it easy to put on muscle, and secondly because I’ve never found it easy to be good at distance running. Once I got on Strava I began to see how often quicker runners are able to get better results despite training half as hard as I do. I seem to lack the natural aerobic capacity that many distance runners have.

This is all behind the reason why I decided to give 800m running a try. It’s an event that still needs decent sprint speed backing it up. But when I started following a plan by Jack Daniels eighteen months ago, it didn’t do much for speed recruitment and I made a deliberate decision not to overdo things as I found it easy to run quicker than expected. This again is another reason why I think I’m better suited to short distance racing.

Even so I felt my top-end speed was missing as I could barely get my peak speed below five minute mile. Last February, I started looking at how to improve cadence in the hope this would improve my form for sprinting and top end speed. Six months ago I started doing ten minutes of sprint drills twice per week to clean up my technique. It’s made a huge difference.

So here I am doing Summer Training to build speed and peak for my next 800m attempt. With my aerobic base enabling me to run seven minute miles for an hour in the winter, I decided it was time to introduce hill and flat sprints on a Monday to recruit more running muscle and get faster at the top end. It seems to be working.

Six years ago, I was doing the same set of workouts and my times then for 60m, 80m and 100m approx. were 10½ secs, 12 secs, 16½ secs. Admittedly I tended to do these after another session but this year I’ve recorded times of 8.75s (60m), 11.5s (80m), 14.6s (100m). A definite improvement and fairly good considering I’ve barely done anything like this in the past half-decade and I’m now in my fifties.

I also found on the most recent block of flat sprints I was hitting some high cadences with the two highest values coming in at 262 and 278 on different efforts. I’m slightly wary of whether the cadence monitor is wholly accurate but if it is these are genuine sprint numbers. Again this backs up the belief my form is improving.

The rest of May’s training was something of a slog to hit target paces. Quite often I missed my faster targets but the legs always seemed sluggish after the sprints. This resulted in a decision – I’ve decided though that working on speed over this summer is the priority so if other sessions are a little behind because of that, so be it. Overall my numbers are still an improvement over where they were a year ago.

On into June. This is the hardest block of training. I’ve felt tight and slow on recovery days but hopefully I’ll get through it!