shorter gastrocs, longer achilles in black women: more efficient walking economy?

[TPT]

ethnic differences in muscular cross sectional areas and performances are widely discussed in bodybuilding and sports. whether controversial or not, objective applications from science can be used in otherwise subjective discussions.

well, the following paper by mccarthy et al. (2006) provided some insight to differences in gastroc development and performance between african american and caucasion women.

ill be back for a review and discussion.
Ethnic Differences in Triceps Surae Muscle-Tendon Complex and Walking Economy

MCCARTHY, JOHN P.; HUNTER, GARY R.; LARSON-MEYER, D. ENETTE; BAMMAN, MARCAS M.; LANDERS, KATHLEEN A.; NEWCOMER, BRADLEY R.
The Journal of Strength & Conditioning Research. 20(3):511-518, August 2006.

Medial gastrocnemius and total triceps surae muscle shape were different across ethnicity despite ...





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Abstract:

The purposes of this study were to (a) determine whether structural differences in triceps surae muscle-tendon complex and walking economy exist between 14 African American and 19 Caucasian sedentary women and (b) determine whether muscle-tendon parameters are associated with walking economy. African American and Caucasian subjects were matched on body weight, height, and body composition. Muscle-tendon parameters were determined by magnetic resonance imaging and walking economy was evaluated at 4.8 km [middle dot]h-1. Medial gastrocnemius and total triceps surae muscle shape were different across ethnicity despite no ethnic differences in plantar flexion strength or in maximal cross-sectional area for any triceps surae muscles. African American women had shorter gastrocnemius muscles and longer tendons and performed walking more economically. Tendon length was the only variable related to walking economy. No ethnic differences were observed in walking economy after adjusting for tendon length. Data show gastrocnemius tendon length is related to level walking and longer gastrocnemius tendons may partly explain more economical walking in African American women. These preliminary findings indicate the structure of the muscle-tendon complex could be a factor partially accounting for reported ethnic differences in certain types of athletic-related performance.
(C) 2006 National Strength and Conditioning Association
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[Dr Pangloss]

i believe there is also a study on kenyan runners and calf structure. The conclusion was that the tiny calves with high gastroc insertions allowed for a greater efficiency of stride, since the cost of moving the lower leg forward and kicking back was less per stride than a longer calf.

[TPT]

ok.

so maccharthy et al. (2006) investigated whether there were differences between the triceps surae of black and white women, gastroc tendon length, walking economy. also, the authors studied whether the gastroc and tendon are related to increased walking economy using steady state treadmill.

no significant differences in leg length were found though black women were still longer when adjusted for height. max cross sectional area of th triceps surare was not significantly different though white women had longer medial and lateral gastroca`lengths than African American women after adjustments for leg length. Medial, lateral, and average gastroc

tendon lengths were 2.1 cm, 1.5 cm, and 1.8 cm longer in the black women than in the white women when adjusted for leg length. significant interaction between ethnicity and anatomical cross-sectional area was found for total triceps surae and medial gastroc supporting the idea that these muscles are different in shape across ethnicity.

Black and while women showed the same levels of max plantar flexion strength. white women had significantly higher VO2max, walking VO2, and walking economy than African American women. However, after adjusting for average gastroc tendon length, walking economy was no longer significantly different between black and white women. max cross sectional areas of triceps surae and plantar flexion strength were ruled out as as potential confounds for ethnic differences in walking economy and offered support for the strong similiarity of the two groups compared. Gastroc tendon length was the only variable tested in this study that was significantly correlated to walking economy.

so just to iterate, after adjusting walking for tendon length the difference seen between black and white women in walking economy no longer existed. the authors hypothesized that longer gastroc tendons in the black women can potentially store and reuse more elastic energy and account for differences between walking economy.

much of these hypotheses are yet to be validated so we have to tread lightly on assumptions for differences in mechanisms of the triceps surae. this study still gives us insight to plausible accounts of functional differences derived from architectural differences.

differences in athletic performance may have greater to do with inherent biomechanical differences than what the general public gives credit to. politics and morality may prohibit us from chatting about ethic differences and performance but science should not.

what did you guys think of this paper?

[TPT]

i believe there is also a study on kenyan runners and calf structure. The conclusion was that the tiny calves with high gastroc insertions allowed for a greater efficiency of stride, since the cost of moving the lower leg forward and kicking back was less per stride than a longer calf.

was that the study that compared to scandanavians? post the reference when you get a chance.

yeah, data shows differential longer leg lengths that would increase gait step length and stride. it makes sense to have less steps per distance. we do see everyday relative long legs and short trunks in people of african descent.

more interesting are the properties of tendons. longer tendons such as the achilles have greater potential to store energy, recoil, and consequently generate forces.

athletes are not made equal- so to speak.