Inflexibility may enhance running economy

fletch wrote:

We do it all the time through strength training.

Yes, and ROM is probably reduced through lots of running as well. Complete inactivity with no stretching would probably accomplish the same thing. But deliberate reduction in flexibility has never to my knowledge been the goal or purpose of strength work, of running, or of lying around doing nothing.

Has anyone ever said, "Alright guys, today we're going to work on making our legs less flexible!"?

Mad Sk1llz wrote:

Stretching a waste of time, unless you have a specific issue to work out.

The "need for flexibility" gets harped on by the same self-indulgent types who waste money on massage and foamy bath gels.

Just run, baby.

You can quote me on that.

Go run a 5k in faster than 20 minutes someday and maybe we will.

'Tis but a scratch wrote:

fletch wrote:

We do it all the time through strength training.

Yes, and ROM is probably reduced through lots of running as well. Complete inactivity with no stretching would probably accomplish the same thing. But deliberate reduction in flexibility has never to my knowledge been the goal or purpose of strength work, of running, or of lying around doing nothing.

Has anyone ever said, "Alright guys, today we're going to work on making our legs less flexible!"?

You're right, no one will directly say that, but we do certain things in training that lead to "inflexibility", such as, running a lot and doing strength training. It's not like we're avoiding it. But again, you're right, it would be a novel concept to do certain types of training to stiffen the MTU's of the lower leg in order to improve running economy.

this is letsrun, scientific analysis is considered stupid and counterintuitive to running training.

fletch wrote:

... it would be a novel concept to do certain types of training to stiffen the MTU's of the lower leg in order to improve running economy.

And to do that deliberately, we'd probably have to know exactly which units to target. Reducing ROM globally could easily have a negative effect. Running itself, along with some hill work and a few rapid-fire running drills, will turn out to be best for arriving at the ideal ROM, eccentric loading capacity and correct force production.

There is a difference between flexibility and adequate range of motion. You can be too tight, but also too flexibility. Just don't go overboard with stretching and all will be well.

Alan

'Tis but a scratch wrote:

fletch wrote:

... it would be a novel concept to do certain types of training to stiffen the MTU's of the lower leg in order to improve running economy.

And to do that deliberately, we'd probably have to know exactly which units to target. Reducing ROM globally could easily have a negative effect. Running itself, along with some hill work and a few rapid-fire running drills, will turn out to be best for arriving at the ideal ROM, eccentric loading capacity and correct force production.

exactly. We are targeting the MTU's of the triceps surae group. Again, back to ROM, I don't think there will be any difference as far as the amount of stretch placed on the MTU's of the TS group before and after "stiffening training". So, if you can increase stiffness without a decreased ROM (basically the acute angle between the foot and shank), theory would suggest you would load and subsequently release more elastic energy from the tendon.

check out the following reference:

The Journal of Experimental Biology 209, 3345-3357

Published by The Company of Biologists 2006

The purpose of this study was to test the hypothesis that

runners having different running economies show

differences in the mechanical and morphological

properties of their muscle–tendon units (MTU) in the

lower extremities. Twenty eight long-distance runners

(body mass: 76.8±6.7·kg, height: 182±6·cm, age: 28.1±4.5

years) participated in the study. The subjects ran on a

treadmill at three velocities (3.0, 3.5 and 4.0·m·s–1) for

15·min each. The VO2 consumption was measured by

spirometry. At all three examined velocities the kinematics

of the left leg were captured whilst running on the

treadmill using a high-speed digital video camera

operating at 250·Hz. Furthermore the runners performed

isometric maximal voluntary plantarflexion and knee

extension contractions at eleven different MTU lengths

with their left leg on a dynamometer. The distal

aponeuroses of the gastrocnemius medialis (GM) and

vastus lateralis (VL) were visualised by ultrasound during

plantarflexion and knee extension, respectively. The

morphological properties of the GM and VL (fascicle

length, angle of pennation, and thickness) were determined

at three different lengths for each MTU. A cluster analysis

was used to classify the subjects into three groups

according to their VO2 consumption at all three velocities

(high running economy, N=10; moderate running

economy, N=12; low running economy, N=6). Neither the

kinematic parameters nor the morphological properties of

the GM and VL showed significant differences between

groups. The most economical runners showed a higher

contractile strength and a higher normalised tendon

stiffness (relationship between tendon force and tendon

strain) in the triceps surae MTU and a higher compliance

of the quadriceps tendon and aponeurosis at low level

tendon forces. It is suggested that at low level forces the

more compliant quadriceps tendon and aponeurosis will

increase the force potential of the muscle while running

and therefore the volume of active muscle at a given force

generation will decrease.

the proper stretch program enhances running economy. static stretching is by far the worst method of flexibility out there. it does nothing to improve flexibility, reduce injury, and everyone seems to follow it, and wonder why they are always in the trainers room. hmmmm get with it, static is NOT the way to go