Can you cross-train your way to completing a 95mi trail running ultramarathon? (pt.3)
After some easy days of recovery from Tempo workouts on the bike, this week’s training marked the point of switching the focus from building VO2max to pushing up my lactate threshold. It also marked a turning point in my road to recovery which has enabled me to find my feet again! More of that later, but first, reading back I realised I glossed over a proper definition of lactate threshold; which is an important metabolic marker and determinant of performance. So let’s look at that now.
Lactate threshold - the maximum work rate you can sustain for a long duration
Think of this as the top (sustainable) speed that will get you to your destination. Now let’s imagine there’s a shiny new electric car sitting in the driveway. Spec says it can hit a top speed of 145mph. Well, aside from it being illegal and reckless to drive around at that speed…it is simply not sustainable, it would quickly run out of charge and grind to a halt. Rather it would be much more sensible to dial that back to a (legal) speed the battery charge will sustain for a lot longer.
Much like your running; if you blast out the door and exceed your top sustainable speed, your batteries will soon run down. This is the point where blood lactate accumulates faster than you can process it. You’ll recognise this as your legs starting to feel heavy, accompanied by an intense burning sensation, ultimately forcing you to slow down or stop altogether.
Increasing your top sustainable speed
If we’re going to improve (and outpace competitors in a race) we want to increase our top sustainable speed. To achieve this I include threshold runs into the mix. Running at a rate of perceived effort (RPE) of 7-8 on a scale of 1-10. This would be around 20-30” slower than your 10k pace. These are hard intervals that work the metabolic system at or just below lactate threshold. Examples of threshold runs would be:
Progression run: if you’re new to this sort of intensity, I’d start here. This workout involves beginning at a very easy pace and gradually increasing your speed by c. 20-30” each interval until you are running at an effort of 7-8 or achieving the pace described above. For example, you could start with a 10-minute warm-up, then gradually increase your pace for the next 30 minutes until you are running just below your 10k pace. Or it could be more structured, for example; 6 x 1km or 1mi intervals, each one progressively quicker than the last. Finishing with a 10mins cool down.
Continuous intervals: these are a bit more advanced so warm up well for 15-20mins, then lift the pace to around 20-30” slower than your 10k pace for a set amount of time or distance. The goal is to maintain that target pace (or RPE 7-8 effort) for the duration of the interval. For example, as your fitness progresses over time, you could move from a 1 x 40min interval to 2 x 25mins, to 2 x 30mins with 4mins easy recovery between intervals. Remember to cool down for at least 10mins.
As with any training, build up very gradually and if you are at all unsure, reach out to a coach (gentle nudge…that could be me!) for some help and advice to tailor a training programme that suits your running history, current fitness and goals.
What to expect from training at or just below lactate threshold
In my last post I discussed why I was gearing my training above lactate threshold and the benefits that would bring. Now let’s look at the role of training at or just below the lactate threshold. Ultimately the goal is to lift the lactate threshold to enable the body to work harder/run faster for longer periods of time while not fatiguing as easily. Training at this point supports that goal by eliciting the following adaptations:
Increased aerobic capacity: improved ability to transport and use oxygen, which can increase aerobic capacity and endurance
Enhanced fat utilisation: adapting the body to use more fat as fuel, which can be especially helpful for endurance athletes who need to conserve glycogen stores
Improved buffering and clearing of lactate from the bloodstream: allowing you to maintain higher intensities for longer periods
Mental toughness: these hard runs can be mentally challenging, and consistent training at this intensity can help build mental toughness and resilience (there’s that magic ingredient again!)
Road to recovery and finding my feet (again!)
Things have taken a significant step forward in my recovery process. Continued adherence to the prescribed physio rehab exercises is strengthening the damaged/weakened right side gluteus medius. Whilst a single 20min session with an osteopath has rectified the root cause of my problems; the lumbar spine.
The back pain has gone. The muscle stiffness is mostly gone. Normal range of motion is restored. There’s a revived feeling of stability and strength in every step and stride. And sleep has massively improved, thus completing the virtuous circle as my body benefits from the restorative effect of sleep. I was a little apprehensive going into it and it may not be for everyone, but I can highly recommend Tom McMullen of Choice Osteopathy.
So, that and the physio has allowed me to find my feet again. Cautiously building up time on feet and trying out small intervals at higher intensities. Splitting my running workouts across the day has also been a tactic I’ve introduced with success. As the injury took hold, a 2.5hr run started to trigger muscle issues. However an 80min morning run, followed by an 80min evening run has not.
Cross-training beginning to bear fruit
Fear not readers, despite this miraculous recovery, this is not the end of the experiment. I’m still committed to testing the input of, and switching in, cross-training to complete the training programme for the WHW ultramarathon. It’s still going to be central to achieving the desired volume of training hours as I very gradually and cautiously increase the running volume; I’m not wanting to blow this! But also, why would I ditch cross-training…when it’s beginning to bear fruit without the same ‘cost’ as running. Comparable weeks of training load and duration; 100% running vs a 40:60, run to cross-training split is not inducing the same level of fatigue. I feel fresh and ready for each workout, I can feel my fitness growing, I can see my metrics improving, and even Garmin tells me my VO2max has increased. Thanks Garmin!
So the journey continues and on that note, the pedals in the garage await my presence!