Running biomechanics: shorter heels, better economy (original) (raw)

Longer Achilles tendon moment arm results in better running economy

Physiology International, 2021

Based on the current literature, the link between Achilles tendon moment arm length and running economy is not well understood. Therefore, the aim of this study was to further investigate the connection between Achilles tendon moment arm and running economy and the influence of Achilles tendon moment arm on the function of the plantarflexor muscle-tendon unit during running.Ten male competitive marathon runners volunteered for this study. The participants ran on a treadmill at two running speeds: 3 and 3.5 m s−1. During running the oxygen consumption, lower leg kinematics, electrical activity of plantar flexor muscles, and fascicle behavior of the lateral gastrocnemius were measured simultaneously. On the second occasion, an MRI scan of the right leg was taken and used to estimate the Achilles tendon moment arm length.There was a negative correlation between running economy and the body height normalized moment arm length at both selected speeds (r = −0.68, P = 0.014 and r = −0.70, ...

Tendon Length and Joint Flexibility Are Related to Running Economy

Medicine & Science in Sports & Exercise, 2011

Purpose: 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 mrming (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 (NV06 and NV07, 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 NV07 (r =-0.43, P = 0.03) and approached significance"for NV06 (r =-0.36, P = 0.06). Flexibility of the plantar flexors was related to NV07 (-K).38, P = 0.05). Multiple regression showed that Achilles tendon length was independently related to NV06 and NV07 (partial r varying fi-om-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.

Shorter heels are linked with greater elastic energy storage in the Achilles tendon

Nature Scientific Reports, 2021

Previous research suggests that the moment arm of the m. triceps surae tendon (i.e., Achilles tendon), is positively correlated with the energetic cost of running. This relationship is derived from a model which predicts that shorter ankle moment arms place larger loads on the Achilles tendon, which should result in a greater amount of elastic energy storage and return. However, previous research has not empirically tested this assumed relationship. We test this hypothesis using an inverse dynamics approach in human subjects (n = 24) at speeds ranging from walking to sprinting. The spring function of the Achilles tendon was evaluated using specific net work, a metric of mechanical energy production versus absorption at a limb joint. We also combined kinematic and morphological data to directly estimate tendon stress and elastic energy storage. We find that moment arm length significantly determines the spring-like behavior of the Achilles tendon, as well as estimates of mass-specific tendon stress and elastic energy storage at running and sprinting speeds. Our results provide support for the relationship between short Achilles tendon moment arms and increased elastic energy storage, providing an empirical mechanical rationale for previous studies demonstrating a relationship between calcaneal length and running economy. We also demonstrate that speed and kinematics moderate tendon performance, suggesting a complex relationship between lower limb geometry and foot strike pattern. The role of the Achilles tendon (AT) in elastic energy storage with subsequent return during stance phase is well established 1-7. Recovery of elastic energy imparted to the AT is potentially influenced by AT morphology in three ways: (1) material properties of the tendon, (2) cross-sectional area of the tendon, and (3) the moment arm of the calcaneal tuberosity loading the tendon against the muscle force of the m. triceps surae (i.e., foot geometry). Previous work suggests that foot geometry may explain variation in how much potential energy is stored in the tendon, finding that a shorter AT moment arm is correlated with lower mass-specific energy costs of locomotion (COL; L O 2 kg −1 s −1) 8, 9. This finding suggests that shorter AT moment arms are associated with greater elastic loads imparted to the tendon, which are then recovered as kinetic energy during the support phase of each gait cycle 9 , thereby reducing COL. Scholz et al. 9 also suggest that the length of the AT moment arm is a more significant factor in explaining COL than variation in material properties of the tendon itself or size-related variation in the cost of swinging the leg forward during the aerial phase of the gait cycle 9. However, assumptions about the interacting roles of AT moment arm length, tendon cross-sectional dimensions, and tendon material properties on variation in elastic energy storage have yet to tested in an integrated manner. Moreover, Scholz et al. 9 doesn't directly measure the variables in the model which predict variation in elastic energy storage, including muscle force and the external moment arm. Finally, because previous studies of how AT moment arm length influences COL have used trained runners running on a treadmill at a speed of 16 km/h, it is still unknown how variation in speed and athletic training impacts elastic loading to the tendon in relation to moment arm length. While previous work has explored elastic loading of the AT at different speeds and under different loading conditions 10-21 , this study is the first to investigate the potential correlation between foot geometry like the AT moment arm length and spring-like behavior of this tendon in humans. In this study, we model elastic loading of the AT by characterizing the spring-like behavior over the support phase of each gait cycle using two metrics. First, we calculate specific net work (SNW) at the ankle joint. SNW is OPEN

Influence of the muscle-tendon unit's mechanical and morphological properties on running economy

Journal of Experimental Biology, 2006

SUMMARYThe 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 \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({\dot{V}}_{\mathrm{O}_{2}}\) \end{document}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 differen...

Muscle Fiber Type, Achilles Tendon Length, Potentiation, and Running Economy

Journal of strength and conditioning research / National Strength & Conditioning Association, 2015

The purpose of this investigation is to develop a potential model for how muscle fiber type, Achilles tendon length, stretch shortening cycle potentiation (SSCP), and leg strength interact with running economy. Twenty trained male distance runners 24-40 years of age served as subjects. Running economy (net oxygen uptake) was measured while running on a treadmill. Leg press SSCP and SSCP were determined by measuring the difference in velocity between a static leg press throw and a counter-movement leg press throw. Vertical jump SSCP was determined by measuring the difference in jump height between a static jump and a drop jump from a 20.3 cm bench. Tendon length was measured by magnetic resonance imaging, and muscle fiber type was made from a vastus lateralis muscle biopsy. Type IIx muscle fiber percent (r = 0.70, p < 0.001) and leg strength (r = 0.95, p…

Energy cost of running and Achilles tendon stiffness in man and woman trained runners

Physiological Reports, 2013

The energy cost of running (E run ), a key determinant of distance running performance, is influenced by several factors. Although it is important to express E run as energy cost, no study has used this approach to compare similarly trained men and women. Furthermore, the relationship between Achilles tendon (AT) stiffness and E run has not been compared between men and women. Therefore, our purpose was to determine if sex-specific differences in E run and/or AT stiffness existed. E run (kcal kg À1 km À1 ) was determined by indirect calorimetry at 75%, 85%, and 95% of the speed at lactate threshold (sLT) on 11 man (mean AE SEM, 35 AE 1 years, 177 AE 1 cm, 78 AE 1 kg, _ VO 2 max = 56 AE 1 mL kg À1 min À1 ) and 18 woman (33 AE 1 years, 165 AE 1 cm, 58 AE 1 kg, _ VO 2 max = 50 AE 0.3 mL kg À1 min À1 ) runners. AT stiffness was measured using ultrasound with dynamometry. Man E run was 1.01 AE 0.06, 1.04 AE 0.07, and 1.07 AE 0.07 kcal kg À1 km À1 . Woman E run was 1.05 AE 0.10, 1.07 AE 0.09, and 1.09 AE 0.10 kcal kg À1 km À1 . There was no significant sex effect for E run or RER, but both increased with speed (P < 0.01) expressed relative to sLT. High-range AT stiffness was 191 AE 5.1 N mm À1 for men and 125 AE 5.5 N mm À1 , for women (P < 0.001). The relationship between low-range AT stiffness and E run was significant at all measured speeds for women (r 2 = 0.198, P < 0.05), but not for the men. These results indicate that when E run is measured at the same relative intensity, there are no sex-specific differences in E run or substrate use. Furthermore, differences in E run cannot be explained solely by differences in AT stiffness.

Ankle joint mechanics and foot proportions differ between human sprinters and non-sprinters

Proceedings of the Royal Society B: Biological Sciences, 2012

Recent studies of sprinters and distance runners have suggested that variations in human foot proportions and plantarflexor muscle moment arm correspond to the level of sprint performance or running economy. Less clear, however, is whether differences in muscle moment arm are mediated by altered tendon paths or by variation in the centre of ankle joint rotation. Previous measurements of these differences have relied upon assumed joint centres and measurements of bone geometry made externally, such that they would be affected by the thickness of the overlying soft tissue. Using magnetic resonance imaging, we found that trained sprinters have shorter plantarflexor moment arms (p ¼ 0.011) and longer forefoot bones (p ¼ 0.019) than non-sprinters. The shorter moment arms of sprinters are attributable to differences in the location of the centre of rotation (p , 0.001) rather than to differences in the path of the Achilles tendon. A simple computer model suggests that increasing the ratio of forefoot to rearfoot length permits more plantarflexor muscle work during plantarflexion that occurs at rates expected during the acceleration phase following the sprint start.

Moore 2016 Review of biomechanical factors affecting running economy

Running economy (RE) has a strong relationship with running performance, and modifiable running biomechanics are a determining factor of RE. The purposes of this review were: 1) to examine the intrinsic and extrinsic modifiable biomechanical factors affecting RE; 2) assess training induced changes in RE and running biomechanics; 3) evaluate whether an economical running technique can be recommended and; 4) to discuss potential areas for future research. Based on current evidence, the intrinsic factors that appeared beneficial for RE were; using a preferred stride length range, which allows for stride length deviations up to 3% shorter than preferred stride length; lower vertical oscillation; greater leg stiffness; low lower limb moment of inertia; less leg extension at toe-off; larger stride angles; alignment of the ground reaction force and leg axis during propulsion; maintaining arm swing; low thigh antagonist-agonist muscular coactivation; and low activation of lower limb muscles during propulsion. Extrinsic factors associated with a better RE were; a firm, compliant shoe-surface interaction; and being barefoot or wearing lightweight shoes. Several other modifiable biomechanical factors presented inconsistent relationships with RE. Running biomechanics during ground contact appeared to play an important role, specifically those during propulsion. Therefore, this phase has the strongest direct links with RE. Recurring methodological problems exist within the literature, such as cross-comparisons, assessing variables in isolation and acute to short-term interventions. Therefore, recommending a general economical running technique should be approached with caution. Future work should focus on interdisciplinary, longitudinal investigations combining RE, kinematics, kinetics, neuromuscular and anatomical aspects, as well as applying a synergistic approach to understanding the role of kinetics.

Lower leg muscle–tendon unit characteristics are related to marathon running performance

Scientific Reports, 2020

The human ankle joint and plantar flexor muscle–tendon unit play an important role in endurance running. It has been assumed that muscle and tendon interactions and their biomechanical behaviours depend on their morphological and architectural characteristics. We aimed to study how plantar flexor muscle characteristics influence marathon running performance and to determine whether there is any difference in the role of the soleus and gastrocnemii. The right lower leg of ten male distance runners was scanned with magnetic resonance imagining. The cross-sectional areas of the Achilles tendon, soleus, and lateral and medial gastrocnemius were measured, and the muscle volumes were calculated. Additional ultrasound scanning was used to estimate the fascicle length of each muscle to calculate the physiological cross-sectional area. Correlations were found between marathon running performance and soleus volume (r = 0.55, p = 0.048), soleus cross-sectional area (r = 0.57, p = 0.04), soleus...