Paula Radcliffe is one of the greatest marathon runners of all time. At the start of her career, she was very good but not dominant. An analysis of her progress as she came onto the world stage revealed a significant increase in running economy with a significant decrease in V̇O2max as she rose from a solid junior athlete to an international star. So, while her maximal aerobic ability declined, her running economy improved and her endurance performance took her to the top of the sport. Similarly, one of the earliest longitudinal studies in running was on the miler Steve Scott; his improved performance was due to improved running economy without a change in V̇O2max. So, while maximal aerobic capacity is important for endurance runners, running economy matters more.

In 2006, a studyof elite distance runners from Eritrea and Spain, with matched V̇O2max values, concluded that the reason for the superiority of the runners from the African nation was primarily their significantly greater running economy. 

By 1980, it was recognized by Conley and colleaguesthat "among highly trained and experienced runners of comparable ability and similar V̇O2max, running economy accounts for a large and significant amount of the variation observed in performance on a 10 km race.” 

In 1985, the legendary coach and scientist, Jack Daniels published an articlethat was a call-to-action on developing a better understanding of running economy as an independent and relevant endurance performance metric, noting the numerous examples of runners with better economy beating runners with higher V̇O2max values.

How can you improve your running economy? One way is through heavy resistance training. As early as the 1980s, we begin to see published studies demonstrating the positive effects of heavy resistance training on endurance capacity and performance. In 1988, Hickson and colleagues reportedthat a heavy strength training program improved indices of endurance performance. In a 1995 studyof female collegiate distance runners, a strength training program improved running economy by about 4%. In that study the runners progressed from 2-3 sets of 10 repetition maximum (RM) to 2-3 sets of 5 RM over the course of 10 weeks. There were no changes in body mass or fat measurements, V̇O2max, or limb circumferences. Indeed, it was was recognized long ago that there's a difference between strength and size and that it’s most desirable to improve strength without increasing size for runners. This is easily accomplished following current guidelines, which I outline below. In 2008, Støren and colleagues reportedthat maximal strength training improved time-to-exhaustion at maximum aerobic speed and running economy at 70% V̇O2max, which is the approximate average intensity for many ultra-marathons.

Meta-analyses are studies of studies - they compile all the previous unique studies on a subject with the purpose of leveraging the power of numerous studies to draw generalizable and broadly reliable conclusions. A 2006 meta-analysis reported that “maximal-force training led to greater improvements than other intensities. Subgroup analyses also revealed that beneficial effects on performance were consistent irrespective of the athletes’ level.” According to Dr. Keith Baar, my guest on episode 58, one set of very heavy weight lifting moved slowly and to fatigue in about 8 repetitions is sufficient. This is supported by a study showing that hypertrophy is a function of volume while strength gains are not; a single (or two) sets to fatigue in less than 10 repetitions enhances strength and force transfer - which support economy - without making muscles bigger (without hypertrophy).

Fast forward to 2018 and multiple meta analyses (e.g., hereand here) found that strength training improves economy of motion for endurance athletes from many sports, including running - both moderately and highly trained distance runners - and that the effect is most prominent for maximal-force training and less, but still significant, for maximal-power training. What this means is that a slow, maximum effort is the most effective approach. Again, avid listeners of SOUP may recall Dr. Keith Baar in episode 58 explaining that a single set with even 1 or 2 maximum efforts (i.e., with maximum resistance or even maximum isometric effort) is effective and sufficient to strengthen the connective tissue linkages within muscle and connecting muscle to bone such that the efficiency of force transmission is stressed for maximal adaptations. Greater connective tissue stiffness and stronger linkages from the muscle cell proteins, like dystrophin, to the extracellular collagen-based matrix results in more efficient tension development throughout the muscle-tendon-bone system. Slow, heavy resistance does this while matching the strength of the muscle to the stiffness of the tendon for reduced injury risk. Two or three days per week of 1-2 sets of 5-8 repetitions to failure are effective. In fact, you can probably do as little as one maximum-effort (no repetitions) and gain many of the benefits because those tissues are highly sensitive. You can do more but recognize that the connective tissue response, at least in tendons, becomes refractory - that is, non-responsive. 

So, as you organize your resistance training plan know that the two key principles are high resistance that forces slow movement and get it done in less than 10 minutes, which should be easy with just 2-3 exercises of 1-2 sets and 5-8 repetitions. For example, do some warm-up exercise for your legs then the workout might be: 1 set of heavy squats for 5 repetitions to failure, 2 sets of heavy single leg presses each of 5 repetitions to failure, 1 set each of seated and standing calf raises for 6-8 repetitions to failure. This is just an example. Be sure that you start slowly and build up to these maximum efforts over time and that you warm up a bit before your heavy effort in each workout. If you’ve not been doing weight training, then beginning with resistance of 50% of 1 RM is a good place to start and don’t go all the way to failure until you see how your body is responding and how sore you get. We don’t want excessive soreness, especially when starting out.

When should you strength train? The best time is at least 5 hrs separated from any other training of those muscles. For a runner, that means there should be at least 5 hrs between any run and your heavy weight session. I don’t find any clear consensus on whether it’s best to put these sessions on the same day as your intervals or on easy running days. There are good theoretical reasons for both and not enough data for me to give a recommendation; see what works best for you by keeping notes on how fatigued or peppy you feel throughout a week and at the end of a week or two of trying both ways - the best advice at this time is to go with whichever approach makes you feel best. Just keep that 5 hr separation window from runs.  

What if you don’t have access to a gym with heavy weights. Isometric exercise works just as well. If you can find something immovable to simulate a squat, leg press, or calf raise position, do those with maximum effort for 5 seconds on and 5 seconds off for your repetitions. A rope or webbing strap tied in a loop can be used for all those exercises if you’re creative. You can also substitute plyometric exercises, which are rapid movements like bounding and jumping, though these greatly increase injury risk and really require a long buildup of training technique. One alternative you can use right away is jumping rope. Jump rope for 5 minutes every third day and build up to every day if you like. Jump rope for just 1-2 minutes the first time to be cautious, you may be very surprised at how sore your calves can get when you start jumping rope.

An additional benefit of heavy strength training is that it may increase W’ or D’. These are the amount of work and the distance you can run, respectively, above your critical power and critical speed (often called the fatigue threshold). We talked about this fatigue threshold in my discussion with Dr. David Poole in episode 55. Basically, this means that heavy strength training is a tool for enhancing your anaerobic capacity at paces above your fatigue threshold. This only matters for people running shorter races such as 5K and 10K or for those who need a few more steps in a sprint finish of any race. But it also may translate into the capacity to do a little more work or tolerate the work on interval days, which may be a benefit to all runners. That’s off topic from our discussion today on running economy. Just know that there may be additional benefits of heavy weight training in moderation.

What else can you do to improve running economy? Sprint. Sprints of 15-30 seconds have been shown by several research groups to significantly improve running economy, even in well-trained endurance and ultra-endurance runners. The idea of repeated sprints may strike fear in those who recall running repeated sprints in sports like soccer back in your glory days. But fear not. Those sprints were often run with short rest periods such that you were nearly broken by the end of numerous sets of several repetitions and accumulating fatigue. That is not what we need for developing running economy. In fact, we want complete recovery between repetitions. That’s because the stimulus we’re after is promoting structural, neuromuscular, and non-metabolic (non-enzymatic) intracellular adaptations. We specifically are not trying to wear down over the course of repetitions but to maintain peak power and activate as many muscle fibers in the active skeletal muscles as possible. So, recovery between repetitions needs to be complete. Three to four times the bout duration is fine. Short sprints should have big rests (and this).

The mechanisms by which sprints improve running economy have been investigated. One of my favorite studies in 2018was published from the lab of the legendary exercise physiologist Jens Bangsbo in Copenhagen, Denmark. They discovered that 30-second maximal sprints altered the expression of specific proteins in both slow-twitch and fast-twitch motor units. A motor unit is one neuron from the spinal cord and the group of skeletal muscle cells that it controls; episode 59 with Dr. Roger Enokagoes into more depth on motor units if you’re interested. Slower-twitch and faster-twitch motor units refers to the groups of muscle cells you use for running easy and slow up to powerful and fast, respectively. The proteins that the Bangsbo lab found altered by sprint training are ones that influence the efficiency of cellular energy production, tension development, and force transmission. They further found that sprint training improved 10K running performance due to adaptations in both slow- and fast-twitch motor units and that running economy at 60% of maximal steady state, which is similar to the pace for ultra-marathons, was improved through these adaptations in slow-twitch motor units. 

Through these and other studies, physiologists are getting a better understanding of the cellular mechanisms by which sprint training enhances running economy. For you, the specific mechanisms may not be of interest. But this is Science Of Ultra, and we like to know how things work. Ultimately, it’s enough for you to appreciate that sprint training works to improve running economy and then to learn how you can apply that knowledge to your own training. 

Once you’ve developed a solid base of easy to moderate running where you’re running at least 5 days per week and can run at least one hour comfortably without heart rate upward drift, adding economy workouts is a good idea. On 2-3 non-consecutive days per week, run 5-10 sprints of 15-30 seconds all out with complete recovery between. Recovery can be walking or easy jogging. The Bangsbo lab used a recovery duration of 2.5 minutes between 30 second sprints - that’s 5 times the bout duration. Many runners will be fully recovered in less time. What’s important to appreciate is that shortening the rest period does not help you, but it may hurt the quality of your sprints if you cut it too short.

Here are some key papers on sprints for improving running economy:
*15-20 second up steep hill; Barnes lab study and review paperBarnes & Kilding SOUP episode
*30 second shuttle runs; Millet lab study  Millet SOUP episode
*10-40s sprints all out with >5x recovery (e.g., 10x30sec all out twice per week with 2.5 min walking recovery) Bangsbo lab study

Maybe you really don’t like running sprints. Is it necessary to run sprints or can you just run fast sometimes without going all out and still improve running economy. A 2006 study (Denadai et al.) found that 2 sessions per week for 4 weeks of interval training at the vV̇O2max improved running economy whereas the same program but running at 95% vV̇O2max did not. The vV̇O2max is the minimum velocity that will result in you reaching your maximum rate of oxygen consumption; it’s just above critical power/critical velocity. While repeated sprints improve running economy without a lot of time investment, you can achieve some improvements in running economy by running intervals at much less intense efforts as long as they are above critical power or critical velocity. How can you determine this value for yourself? Run the three-minute test where you run for three minutes at an all-out sprint from the start and keep pushing 100% for the complete three minutes. It’s a very hard test. But, if you truly give it 100% sprint effort from the start, then your average velocity in the final 45 seconds is a good estimate of your critical velocity. It’s a velocity you should be able to maintain for about 1 hour maximum. Of course it won’t feel like that at the end of the three-minute test. So, on another day try running at that pace and see if it matches to about a 1 hour race pace. Another way to think about this is with the 10K race; your 10K race pace is above critical velocity and can be used as a good starting value for intervals that will provide some benefit towards improving running economy.

The athletes I coach run 15-30 second sprints during economy building phases. Are these on flats, inclines, or declines? Is there a difference among 15, 20, 25, and 30 seconds? The studies show that the differences probably don’t matter much in terms of efficacy for improving economy. You want to be careful of injury risk. Hard sprints downhill, for example, are a higher injury risk than the same sprints uphill. You also want to be aware of meeting the goal, which is to sprint. So, if you choose an incline so steep or a duration so long that you begin fatiguing and slow down, then it’s too much. It’s very important that you can complete all of the intervals without slowing down or fatiguing significantly. Your legs should not be feeling heavy at the end of uphill sprints; if they are, it’s too steep or you’ve gone too long. You should finish these workouts feeling tired but a bit energized and you should always stop while still being able to do a few more before fatigue would manifest. The rule of thumb I like to use is 30 seconds flat or slight decline (1-2%) to 15 seconds at 15% incline. Basically, you start with the notion of 30 seconds flat or at a slight decline and then subtract 1 second for every 1% rise in incline. 30 seconds for zero, 25 seconds for 5% incline, 20 seconds for 10% incline, 15 seconds for 15% incline. But, you don’t have to be too precise with this; it’s a general approach. Let experience guide an empirical decision for the time and incline relations you choose.  

Is there a third tool for improving economy? Maybe. It’s thought that the more running you can do, the more economy you will develop. Of course you have to stay free of injury and there will be a limit on how much improved economy you can get from increasing volume. For many years, top running coaches have emphasized the importance of steadily increasing running volume at sustainable efforts no higher than marathon pace for improving endurance running performance. I started this episode talking about Paula Radcliffe’s rise to prominence. While her V̇O2max was declining and her running economy improving, her overall volume increased substantially as well. 

In research on junior and elite national level endurance athletes across several sports in work from several scientists including Dr. Stephen Seiler, my guest in episode 71, improved performances over seasons and years track with increases in volume of easy training. We’ll have an episode on zones of intensity in a future episode but easy is zones 1 and 2 in a 5-zone model and zone 1 in a 3-zone model. It's one of the reasons I say that ‘recovery runs’ don’t exist. While it’s true that you may go on an easy run following a hard day of training, and therefore think of it as a day in which you're recovering, to me that’s a net recovery day because there’s more recovery going on than breakdown. The easy run you go on is stimulating improvements in your endurance capacity regardless of what you did the day before. It may be a run you do while the net for the day is recovery but the run itself is its own stress.

While we’re on the subject of building volume at easy paces, it’s important to note that you must maintain your overall volume of easy running as you gradually add economy training. In studies where volume of easy running was reduced with the addition of high intensity training, to maintain overall training load, subjects got faster for short duration running but lost important features of the capacity for endurance. So, once you’ve built your easy volumes, add sprints into the training while maintaining your volume of easy running.

A final note on developing overall economy for ultra-marathons. There may be a lot of hiking in your longer races. Hiking is different from running. Walking is different from hiking. A lot of running does not make you a good hiker. And, walking around at work and throughout your daily life does not make you a good hiker. Practice hiking fast in training, a lot, if hiking is part of your races, especially in the final 4-6 weeks before a long ultra-marathon. You don’t just want your running to be faster, you also want your hiking to be faster. I’ve been out on trails with veteran long-distance backpackers and it’s astonishing how fast and efficiently they hike, faster than many runner's jogging pace. For most people who don’t do a lot of hiking, it’s easier to cut minutes off your hiking speeds than it is to cut seconds off your running speeds. Over 50+ miles, that can add up to greatly improved performance.

That brings our summary of key features in developing running economy to a close. We previously explored development of endurance as part of our dive into the plan to develop stamina (script of that episode here). In the next post on training your body, we’ll explore the basics of interval training to enhance stamina once you have a foundation of endurance and economy.

Remember to keep it all in perspective. We run because we love running. If diving into these details detracts from your joy or adds negative psychological stress to your running, then ignore it and just go out and run. Fun always comes first.

Some additional studies that may be of interest:

Eur J Appl Physiol. 2003 Mar;89(1):1-7. Epub 2002 Dec 24. The effect of plyometric training on distance running performance. Spurrs RW1, Murphy AJ, Watsford ML. PMID:12627298

J Strength Cond Res. 2006 Nov;20(4):947-54. Short-term plyometric training improves running economy in highly trained middle and long distance runners. Saunders PU1, Telford RD, Pyne DB, Peltola EM, Cunningham RB, Gore CJ, Hawley JA. PMID:17149987

J Strength Cond Res. 2003 Feb;17(1):60-7. Improvement in running economy after 6 weeks of plyometric training. Turner AM1, Owings M, Schwane JA. PMID:12580657

"CONCLUSION: Explosive training and heavy weight training are effective concurrent training methods aiming to improve RE within a few weeks. However, long-term training programs seem to be necessary when the largest possible improvement in RE is desired.”

"Running economy (RE) was measured in 20 of the studies and generally showed improvements (2-8%) compared to a control group, although this was not always the case. Time trial (TT) performance (1.5-10 km) and anaerobic speed qualities also tended to improve following ST. Other parameters [maximal oxygen uptake ([Formula: see text]), velocity at [Formula: see text], blood lactate, body composition] were typically unaffected by ST.”

An important factor in minimizing the energetic cost of running includes "low thigh antagonist-agonist muscular coactivation”. Strides, sprints, hill surges are intended to reduce coactivation by improved neuromuscular recruitment patterns. They may also improve other factors: "alignment of the ground reaction force and leg axis during propulsion” and "low activation of lower limb muscles during propulsion”. Plyometrics and heavy strength training may result in "greater leg stiffness”, another important factor.