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Life in the Fast Lane ?

Sprinting : my Achilles heel! The long and the short of it!

I thought I would see how many topical and pun-like titles I could use for this blog!

The timing of this blog, after the successes of the club’s Chedworth 10, Tim Francis’s conquering of the Bob Graham, and the trials and tribulations of our three members attempting to run the Cotswold Way’s 100 miles, would enable me to present a view at the other extreme of running distances : 100m and 200m, hence the “long and short of it”.

The reference to Achille’s heel (sorry for the awful play on words), is because my sprinting performance this year has been greatly affected by both my Achilles. More on that later. I thought as a year had nearly passed I would provide an update on how the sprinting has gone, especially compared to the goals I set last Autumn, after my first season “on the track”.

There’s been some great athletics this past summer : World Championships in Eugene, Oregon; Commonwealth Games in Birmingham; European Championships in Munich, and the Vets League Western Division meetings in Oxford, Abingdon and Swindon!

To refresh your memories, my main goal for this year had been to reduce my 100m PB from 16.1s to sub-15 seconds (~10%) through a combination of more underpinning strength and improved technique. Unfortunately, I did not achieve that and my times for the 100m and 200m this year have actually been a somewhat slower!

Achilles "Injury" Impacts

So, what’s happened? Well, like all other runners, there’s always an excuse, and perhaps in this case, a good reason. I strained my Achilles back in September ’21 following two races on the same day and a training session 2 days later. Although, not an immediate injury, it was ‘acute’, not chronic which is more typical for endurance runners.

The sore Achilles did not stop me from training, although I trained in my trainers rather than my spikes on the track, but it did constrain my speed and ability to do the explosive training exercises, e.g. plyometrics, that convert under-pinning strength into real speed gains.

I use the stopwatch rather than a GPS for training for timing accuracy reasons

The ‘injury’ didn’t stop me from doing weight training and I nearly achieved my squat and deadlift targets (110kg cf 120kg deadlift and 80kg squat cf 85kg) but I could not really do the plyometrics until my Achilles improved.

It’s the classic dilemma : rest results in weakening of muscles and tendons, which makes further injury more likely, for the same loading, unless one strengthens them. So, by doing some gentle exercises I was able to reintroduce ‘plyos’ in February (4-5 months after the strain). By March I could do a sprint session at the track, albeit I was noticeably slower. By April, I could do a whole sprint session in spikes but was still about 6 weeks behind “schedule”, so I missed the early season races.

One of the consequences of the sore Achilles was the inability to train “flat out”. Endurance runners rarely train at 100% RPE, but sprinters do and it's important to do so.

You need to build the capability to apply massive force into the ground and maintain it for short durations but at high speed. The intensive training, albeit for short bursts (seconds) is a really good weight control method, much better than High Intensity Interval Training (HIIT) sessions in the gym or steady running (Run repeat article :

Weight Gain and its Impact

As I could not generate the intensity, my weight increased over the winter, so that when I did start competing in the summer, I was a stone heavier (6-7kg) than in 2021.

We all know that carrying ‘un-useful’ weight slows us down. For endurance runners, every un-useful pound is equivalent to losing 1 to 2 seconds per mile, so a stone would add two minutes to your 10k time! Similarly, extra “baggage” impacts a sprinter, because it requires additional force to move it, and you’re already on the limit of your strength.

NB I use the word “un-useful” as obviously we do need some weight to be alive and to move, but I am referring to those added pounds we gain by just eating more calories than we expend and that the body stores as additional fat.

So, have I gone backwards of forwards? Athletes are always told to “follow the process” for good reasons, i.e. you may just have a “bad day at the office”. Therefore, I did some simple analysis (using mechanics) to understand if it’s just the extra weight that’s impacting on my progress (see Addendum if you’re really interested in the analysis). It wasn’t, but the weight wasn’t helping. Therefore, I needed to get my weight down.

Training for the Right Results

So why didn’t I just go for long runs, like I have done successfully in the past? For instance, I used to run about 25 miles per week, over about 3 plus hours. This would be equivalent to about 3,500 calories, which is a pound of fat!

Well the answer is down to the training principle: “specificity”. If you want to train for a Parkrun, you train differently to that for a marathon, and the differences for sprinting are even greater. Both Parkruns and marathons require resistance to fatigue in muscles and this is what ‘slow twitch’ muscle fibres are really good at.

Whereas, short delivery of maximum power requires the use of ‘fast twitch’ muscle fibres. We are all born with three muscle types : slow twitch (“type I”), fast twitch (“type IIb” or “IIx”) and hybrid (“type IIa”) which can perform as type 1 or 2b dependent on training.

Typically, we are born with about 50:50 type I and II, but this does vary with genetics, but as we develop and focus on different sporting activities this changes, i.e. typically :

  • sprinters have about 70 to 75% fast twitch (type II)

  • endurance runners about 75-80 slow twitch (type I)

but ageing preferentially impacts on reducing the amount of Type II fibres, “sarcopenia”; probably one of the reasons older athletes are slower and tend to step up in distances. For a really good guide on muscle fibres, see “Myotypes, the relevance of muscle fiber typology in sports” by Eline Lievens :

After 30 years of endurance running, I need to avoid doing training that encourages slow twitch muscle fibres development. So, I haven’t changed my training pattern, but I have been reducing my calorie intake, i.e. I have gone on a “diet” – ugh!


To control something, one needs to measure it, so I am recording my calories (by weighing my food and using a FitnessPal App) and trying to keep my daily calorie in-take 500 below my expenditure, determined from the health app on my Apple Watch. And this is working (I am currently 65kg), and as the weight comes off, and hopefully my Achilles stays healthy, I can train again at 100% RPE and reduce my dependence on the diet. Short bursts of intense activity kick-starts the metabolic system, as shown by Dr Michael Moseley in “Horizon : the Truth about Exercise” programme and so help burn fat.

NB Anyone thinking of going on a diet to become faster needs to recognise that I was carrying “baggage”. A minimum fat content is required for a healthy body. If one is a lean endurance runner (thanks to Leah Rose Nutrition for the clarification on risks) and are continually training and expending more calories than one takes in, there is a significant risk of ‘RED-S’ (Relative energy deficiency in sport) which can have severe health consequences. I lost the weight that I had put on. I was not trying to achieve an unrealistic weight. I don’t have a gymnastics or swimming coach!

Lighter and Faster?

A consequence of weight loss has been a reduction in the loading on muscles and joints in sprinting and sprint training (plyometrics involve many jumps, including shock-type depth jumps). The goal for sprinters is to apply as much force as possible in the shortest ground contact time possible; hence why injuries are common. A 70kg elite sprinter will deliver 1.6kN of force, with a ground contact time of less than 0.1s ("The Mechanics of Sprinting and Hurdling" by Ralph Mann). This force is over double body weight, hence why sprinters spend time lifting weights in the gym. If your body can deliver a certain force and you lose 5kg or so, then that force should result in an increase in speed of about 2.2% assuming one's technique can manage the greater stride length and/or cadence.

I managed to lose some 10kg from June to early September, resulting in a reduction in my times of 0.4s for 200m and 0.8s for 100m over the season, albeit both still slightly slower (~0.2s) than last year. I am also "feeling" much faster in training. So with continued rehab for the Achilles (icing it most days to stimulate blood flow) and strengthening exercises targeting the soleus muscle, I am optimistic that there’s a basis to achieve next year the goals I set for myself last year. Although this year, I am setting only process related, not outcome, goals.

Addendum – Impact of Achilles problem on speed


I will use some simple equations, recognising that some assumptions are only approximate.

Equation 1 : v = s / t (m/s).

where v is velocity (speed)

Equation 2: s = ut + (at^2)/2. (m)

where s is distance, u is initial velocity (zero), a is acceleration, and t is time.

Equation 3 : F = m.a. (Newtons)

where F is the force, m is mass (weight)

Equation 4 : W = F.s (Joules)

where W is the work done

Equation 5 : P = W / t

where P is the Power

Using data from 2021 and July 2022 for 100m and using equations 1 to 5 :

The last line is a reference calculation for a 10s 100m sprinter weighing 70kg.

The calculation is approximate as sprinters usually reach maximum velocity at about 50-60m and then slow down, so peak velocity is higher than shown and so will the necessary acceleration and forces, work and power be. But they are consistent in methodology and approximation so enable useful comparisons to be made.

The calculations show how the extra weight and the inability to do the activities that convert increased strength into speed (indicated by power or acceleration) are responsible for the slower times (6%). Weight alone is not responsible, else the force and power delivered would be the same for 2022 as 2021.

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The annual prediction run and BBQ will be held on Tuesday 18th June 2024. The run will take place in the Abbey Grounds commencing at 6.30 pm. The BBQ will take place at Cirencester Open Air Pool comme


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