The New Science of Running Form | EP#136

The New Science of Running Form | EP#136

New Science of Running form

A large study (N=97) recently conducted at Loughborough University gives us the best insights we have so far in what aspects of running form and technique actually matter in terms of bringing about improved running economy, and improved performance. 

Discuss this episode!

  • Let's discuss this episode and the topic in general. Post any comments or questions in the comments at the bottom of the shownotes. Join the discussion here!

In this Episode you'll learn about:

  • 39% of running economy variance can be explained with just 3 individual running form parameters.
  • 31% of running performance variance can be explained with just 4 individual running form parameters.
  • The impact on running performance and economy of braking, vertical oscillation, stride parameters (ground contact time, stride rate, stride length, etc), posture, and lower limb angles 

Sponsored by:

Precision Hydration

Precision Hydration
One size doesn't fit all when it comes to hydration. Take PH's free Triathlon Sweat Test to get personalised hydration advice tailored to what you're training for. Use the promo code THATTRIATHLONSHOW to get your first box or tube of electrolyte product for free!

ROKA
The finest triathlon wetsuits, apparel, equipment, and eyewear on the planet. Trusted by Javier Gómez, Gwen Jorgensen, Flora Duffy, Mario Mola, Lucy Charles and others. Get 20% off your entire order with the discount code THATTRIATHLONSHOW.

Shownotes

Evidence base

The study in brief

6:39 -

  • Purpose: determine the relationship between running technique variables and 1) running economy (RE) and 2) running performance.
  • Methods: 97 runners (male and female, various abilities from recreational to elite) ran on a treadmill and RE was measured at various speeds while five categories of kinematic measures (vertical oscillation, braking, posture, stride parameters, and lower limb angles) were recorded. Season best times (converted to equivalent 10k time) were used to assess the relation between technique and performance
  • Results: 19 kinematic variables were individually correlated with RE and 11 with performance. Regression analysis found three variables (pelvis vertical oscillation during ground contact normalized to height, minimum knee joint angle during ground contact, and minimum horizontal pelvis velocity) explained 39% of RE variability. For performance, four variables (minimum horizontal pelvis velocity, shank touchdown angle, duty factor, and trunk forward lean) combined to explain 31% of the variability.
  • Conclusion: This study is the first large-scale study to provide evidence that technique explains a substantial proportion of the variance in RE and performance.

Definition of running economy

  • Running economy (RE) is typically defined as the energy/oxygen cost of running a given distance at submaximal velocity. 
  • It can be measured as kcal / kg / km. The amount of energy per kg bodyweight required to run 1 km. 

A word of warning

  • You should not use this information to go out and try to do a complete makeover of your running stride.
  • As a first step, just become aware of how your running relates to the variables that this study identified as potentially important. 
  • Then make an assessment of if this is something that you can realistically change and if that will help your running based on your ability, goals, and so on. 

Context and background

11:55 -

  • From previous research, there is very little knowledge and concensus about the relationship between running kinematics and running economy and running performance.
  • Most previous studies have been small, and found no results or conflicting results. 
  • Methodologies have often been inadequate.
  • A recent review of strategies to improve running economy provided no recommendations with regard to running technique, confirming that no scientific consensus has been established.  
  • The researchers of this study hypothesised that five aspects of kinematics may influence running economy and performance:
    • Stride parameters
    • Vertical oscillation​
    • Changes in horizontal velocity during ground contact (aka braking)
    • Trunk and pelvis orientation (aka posture)
    • Lower limb angles
running form angles

Lower Limb Angles legend - Click to zoom

  • They set out to create a large study, since the contribution of running technique to both performance and economy is expected to be quite modest so a large sample is needed to get any statistically significant results. 

Participants and protocol

15:00 -

  • 97 regular runners (running two times or more per week and considered the running to be their primary sport or physical activity).
  • These 97 included 29 elite runners (15 males with a 10k SB of better than 31 minutes and 14 females SB of better than 35 minutes for)
  • 68 recreational runners (35 males with a SB of better than 52 minutes for the 10k and 33  females with a 10k SB of better than 57 minutes).
  • They all had a BMI of less than 24 ​
  • They were free from moderate injury in the past three months and free from minor injuries in the past one month.
  • The protocol was an incremental running protocol on a treadmill, starting from a very easy pace and then increasingly getting faster. Lactate samples were collected to measure lactate threshold, and respiratory gas analysis was used to be able to calculate running economy.
  • A number of high-tech cameras allowed them to capture very detailed views of all aspects of their running form, and these videos were used to later calculate the values for each of the running form parameters.
  • The analysis was done at the highest speeds that was below the anaerobic threshold (lactate turnpoint) for all runners, ie. 10-12 km/h. This is slow for the elite runners, but made sure that running economy really was measured at a submaximal velocity for all runners.

Results

19:28 - 

  • 19 kinematic variables were correlated with running economy and 11 with running performance. The correlations were weak to moderate.
  • Individual correlations aren't that strong evidence that any single variable is actually important. Let's say for example, that stride rate is correlated with better running economy. That does not mean that increasing your stride rate will improve your running economy. 
  • A much more powerful way to measure which variables really matter is the multiple linear regression analysis the researchers did where they combined all of the different variables to see which combination of a handful of variables explains most of the variance in running economy and in running performance. 
  • 39.4% of the variance in running economy was explained by a combination of three different variables. 
    • Vertical oscillation of the pelvis normalized to height during ground contact
    • Minimum knee joint angle during ground contact
    • Minimum horizontal velocity of the pelvis (ie. braking)
  • 30.5% of the variance in running performance was explained by a combination of four different variables. 
    • Minimum horizontal velocity of the pelvis (ie. braking)
    • Shank angle at touchdown
    • Duty factor (the percentage of a time that your foot is in contact with the ground compared to your overall stride cycle duration) ​
    • Forward lean of the trunk

Some more details about the more important aspects of running form

31:48 - 

  • Braking (measured as minimum horizontal velocity of the pelvis) seems to be a very important variable. Perhaps the most important one?
  • Vertical oscillation at ground contact was a strong one as well. Do not sit into the ground as you land. Keep your pelvis level and moving forward on the same horizontal line at all times. 
  • Posture: avoid unnecessary rotations and other movements. A forward lean may be beneficial, but I'd advise caution here, because a lot of triathletes already run bent forward at the waist, and that is not what a forward lean of the trunk should look like. If you use a forward lean, make sure you do not bend forward at the waist. 
  • Of the stride parameters, duty factor was the most important one, although lower ground contact time and higher stride rate also had positive individual correlations. They did not contribute to the regression models, though. 
  • Of the lower limb angles, the shank angle at touchdown was the most important one. A smaller shank angle (straighter leg) was better.
  • For uneconomical runners, this study suggests yet again that a low stride rate and too long stride length (over-striding) could be some of the main culprits. 

    Key takeaways

    • Running technique explains a substantial proportion of the variance in running economy and performance. More specifically, it explains 39 percent of the variance in RE, and 31 percent of the variance in performance. This means that you should become aware and pay some attention to certain parameters that you may want to start working on and improving on.
    • The most important technique variables found based on this study are
      • Consistent forward velocity of the pelvis (minimise the decrease in forward velocity, or braking) during ground contact.
      • Minimum vertical oscillation of the pelvis, especially at ground contact.
      • Minimising rotation of the upper body.
      • Duty factor, ground contact time, stride rate.
      • Certain lower limb angles. 
    • Don't over-emphasise the importance of individual variables. Since many of these variables are correlated, it may make more sense to consider at least some of these variables as groups of variables. 

    Links, resources and contact

    Links and resources mentioned

    Connect with host Mikael Eriksson

    triathlon_coach_mikael_eriksson

    Hi! I'm your host Mikael,

    I am a full-time triathlon coach and an ambitious age-group triathlete. My goal is podium at the Finnish national championships within the next few years.

    I first started the website Scientific Triathlon in autumn 2015 as a passion project to share my learnings with a larger triathlon audience. Later on, in early 2017 I started the podcast That Triathlon Show. 

    I sincerely want you to contact me to

    • Send me feedback
    • Give constructive critic​ism 
    • Request topics and guests for the podcast
    • Send me your triathlon-related questions 
    • Tell me that you've rated and reviewed That Triathlon Show so I can give you a shout-out on the show and tell you how much it means to me!
    Subscribe to That Triathlon Show and never miss an episode!

    Discussion

    Let's discuss this episode and the topic in general. Post any comments or questions in the comments below. I'll be here to reply and take an active part in the conversation, so don't be shy! 

    >

    Start training with structure and purpose using the free video series "Effective Triathlon Training Blueprint"