Tendon length and joint flexibility are related to running economy.
OBJECTIVE
The purpose of study was to determine whether quadriceps/patella and Achilles tendon length and flexibility of the knee extensors and plantar flexors are related to walking and running economy.


METHODS
Twenty-one male distance runners were subjects. Quadriceps/patella and Achilles tendon length were measured by magnetic resonance imaging; body composition was measured DXA; oxygen uptake at rest while seated, walking (3 mph), and running (6 and 7 mph) were measured by indirect calorimetry; knee and ankle joint flexibility were measured by goniometry; and leg lengths were measured by anthropometry while seated. Correlations were used to identify relationships between variables of interest.


RESULTS
Net VO2 (exercise VO2 - rest VO2) for walking (NVOWK) and running at 6 and 7 mph (NVO6 and NVO7, respectively) was significantly related to Achilles tendon length (r varying from -0.40 to -0.51, P all < 0.04). Achilles tendon cross section was not related to walking or running economy. Quadriceps/patella tendon length was significantly related to NVO7 (r = -0.43, P = 0.03) and approached significance for NVO6 (r = -0.36, P = 0.06). Flexibility of the plantar flexors was related to NVO7 (+0.38, P = 0.05). Multiple regression showed that Achilles tendon length was independently related to NVO6 and NVO7 (partial r varying from -0.53 to -0.64, all P < 0.02) independent of lower leg length, upper leg length, quadriceps/patella tendon length, knee extension flexibility, or plantarflexion flexibility.


CONCLUSIONS
These data support the premise that longer lower limb tendons (especially Achilles tendon) and less flexible lower limb joints are associated with improved running economy.
Department of Human Studies, University of Alabama at Birmingham, Birmingham, AL 35294-1250, USA. ghunter@uab.edu
Gary R
GR
Hunter
Konstantina
K
Katsoulis
John P
JP
McCarthy
William K
WK
Ogard
Marcas M
MM
Bamman
David S
DS
Wood
Jan A
JA
Den Hollander
Tamilane E
TE
Blaudeau
Bradley R
BR
Newcomer
D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D007866:Leg / Q000033:anatomy & histology / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D009929:Organ Size / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology*; D012420:Running / Q000502:physiology*; D013710:Tendons / Q000033:anatomy & histology / Q000502:physiology*; D016138:Walking / Q000502:physiology