Walk and Run For Life! Through Lever Mechanisms or Spring Mechanisms?

The Human Spring Model is Plyometric Training and Barefoot Running vs The Human Lever Model, Resistance Training and Shod Running

Why the Human Spring Model and Approach is best for an Anti-aging Doctor

by Dr. James Stoxen DC

Bedridden to BarefootReclaim Your Youth

• Bedridden - Bed• Wheel Chair - 4 Wheels• 4-Prong Walker - 10 Supports • Cane - 7 Supports • Orthopedic Shoes and Orthotics - 6 Supports• Orthotics - 6 Supports• Motion Control - 4 Supports • Footwear - 4 Supports • Barefoot - No Supports

Injuries Can Happen When Running

Zola Budd Barefoot Runner

Kinesthetic learning via Kinesthetic Senses

• Strength, efficiency and safety of all movement is determined by neuromuscular factors, in particular the sense of kinaesthesis and the underlying proprioceptive mechanisms which inform us about where all the components of our musculoskeletal system are and what they are doing relative to one another in space and time

 

• The integration of information enables us to execute a given movement in the most appropriate way in terms of pattern, velocity, acceleration and timing.

• One way of improving proprioceptive efficiency is to diminish or block input from other sensory systems.

Roman R. (1986) Trenirovka Tyazheloatleta (Training of the Weightlifter) Fizkura I Sport Moscow

Creep

• Collagenous tissue increases significantly in strength and stiffness with increased rate of loading

• There by emphasizing the intelligent use of training with high acceleration methods.

• One study found an increase of almost 50% in load of knee ligaments to failure when the voting rate was increased for four fold (Kennedy et al 1976)

Tension studies of human knee ligaments. Yield point, ultimate failure, and disruption of the cruciate and tibial collateral ligaments. Kennedy et al 1976 J Bone Joint Surg Am. 1976

Apr;58(3):350-5.

Biomechanical And Physiological Comparison Of Barefoot And Two Shod Conditions In Experienced

Barefoot Runners.

• 8 subjects analyzed using instrumented treadmill analysis• Compared to the standard shod condition when running

barefoot the athletes landed in more plantar flexion at the ankle. • Bare foot running caused reduced impact forces and changes in

stride kinematics.

Squadrone R, Gallozzi C., J Sports Med Phys Fitness. 2009 Mar;49(1):6-13.

Can Barefoot Activity Alleviate Knee Pain and Arthritis

• They looked at the external knee adduction moment (EKAM) when we are wearing shoes and when we are barefoot. EKAM represents knee load distribution from the inside to the outside of the knee joint.

• The higher the EKAM is, the greater and faster the progressions of deterioration (osteoarthritis) of the knee joint.

• these researchers found that sneakers and running shoes increased EKAM when compared to barefoot walking and barefoot running

Radzimski AO, et al, Effect of footwear on the external knee adduction moment – A systemic review, Knee (2011), doi:10, 1016/j.knee. 2011.05.013

Foot Strike Patterns And Collision Forces In Habitually Barefoot Versus Shod Runners

• habitually barefoot endurance runners often land on the fore-foot

• habitually shod runners mostly rear-foot strike, facilitated by the elevated and cushioned heel of the modern running shoe

• Kinematic and kinetic analyses show that even on hard surfaces, barefoot runners who fore-foot strike generate smaller collision forces than shod rear-foot strikers.

• This difference results primarily from a more plantarflexed foot at landing and more ankle compliance during impact, decreasing the effective mass of the body that collides with the ground.

Nature 2010 Jan 28;463(7280):531-5. Lieberman DE, Venkadesan M, Werbel WA, Daoud Al, D’Andre S, Davis IS, Mang’eni RO, Pitsiladis Y.

Effects Of Footwear And Strike Type On Running Economy

• Runners were 2.41% more economical in the minimal-shoe condition when forefoot striking

• 3.32% more economical in the minimal-shoe condition when rearfoot striking• Arch strain was not measured in the shod condition but was significantly greater

during forefoot than rearfoot striking when barefoot. • Plantar flexor force output was significantly higher in forefoot than in rearfoot

striking and in barefoot than in shod running. • Achilles tendon-triceps surae strain and knee flexion were also lower in barefoot

than in standard-shoe running shoe• Minimally shod runners are modestly but significantly more economical than

traditionally shod runners regardless of strike type, after controlling for shoe mass and stride frequency. The likely cause of this difference is more elastic energy storage and release in the lower extremity during minimal-shoe running.

Med Sci Sports Exerc. 2012 Jul;44(7):1335-43. Perl DP, Daoud Al, Lieberman DE Department of Human Evolutionary Biology, Harvard University, Cambridge, MA.

 The Effect of Running Shoes on Lower Extremity

Joint Torques

• 68 subjects ran barefoot and in the same type of stability running footwear

• Three-dimensional motion capture data were collected in synchrony with ground reaction force data from an instrumented treadmill for each of the 2 conditions.

• Increased joint torques at the hip, knee, and ankle were observed with running shoes compared with running barefoot.– 54% increase in the hip internal rotation torque– 36% increase in knee flexion torque – 38% increase in knee varus torque were measured when

running with shoes compared to barefoot.

American Academy of Physical Medicine and Rehabilitation, Vol. 1, 1058-1063, December 2009

The Normal Orientation Of The Human Hallux And The Effect Of Footwear

• The orientation of each hallux was determined in thirty-eight radiographs by measuring the angle

• The wearing of anatomically designed shoes would often allow the hallux to straighten, provided the abductor hallucis muscle functioned adequately.

C. H. BARNETT, J. Anat., Lond. (1962), 96, 4, pp. 489-494

Shod Versus Unshod: The Emergence Of Forefoot Pathology In Modern Humans?

• They investigated the frequency of metatarsal bone pathologies in contemporary and habitually unshod vs shod

• The metatarsal elements from four human groups were examined for pathological variation. Three were from recent rural and urban shod populations (Sotho, Zulu and European) and one from habitually unshod pre-pastoral Holocene people

• The pathological lesions found in the metatarsals of the three shod human groups generally appeared to be more severe than those found in the unshod group.

• This result may support the hypothesis that pathological variation in the metatarsus was affected by wearing of footwear and exposure to modern substrates

B. Zipfel, L.R. Berger, Journal of Clinical Foot Sciences, 17 (2007) 205–213

Shock Attenuation During Barefoot Running

• 8 subjects were instrumented with piezoelectric uniaxial accelerometers to measure Shock Attenuation which were attached to the distal aspect of the right tibia on the medial side and to the front of the head.

• Differences in the kinetics and kinematics of running was observed when comparing barefoot and shod running

• Although the impact at the leg is greater at contact BF, the body is capable of attenuating the impact before it reaches the head.

• Future research is required

Julia A. Freedman, Janet S. Dufek, John A. Mercer

Mechanical Comparison of Barefoot and Shod Running

•35 subjects ran two bouts of 4 minutes at 3.33 m x s(-1) on a treadmill dynamometer•Barefoot showed mainly lower contact and flight time, lower passive peak, higher braking and pushing impulses, higher pre-activation of triceps surae muscles than shod. •It was concluded that when performed on a sufficient number of steps, barefoot running leads to a reduction of impact peak in order to reduce the high mechanical stress occurring during repetitive steps.

Divert C, Mornieux G, Baur H, Mayer F, Belli A, International Journal of Sports Medicine, Volume 26 September 2005 - Page 513 -616

Plantar Pressure Measurements During Barefoot And Shod Running – Relationships To Lower Limb

Kinematics

• 7 subjects • The average velocity of the increase in internal rotation after

contact was related to corresponding ‘heel balance’ velocities.• The high-speed pressure mat measures of barefoot and shod

running (shoe-ground interface) were shown to be predictive of tibial internal rotation velocity.

Mark Robinson and Mark Lake, Liverpool John Moores University, U.K.

Walking Barefoot Decreases Loading on the Lower Extremity Joints in Knee Osteoarthritis

• Gait analyses were performed on 75 subjects with knee OA while they were wearing their everyday walking shoes and while they were walking

• Optoelectronic detection of external markers during ambulation over a multicomponent force plate, and were matched for speed.

• Peak joint loads at the hips and knees significantly decreased during barefoot walking, with an 11.9% reduction noted in the knee adduction moment.

• Shoes may detrimentally increase loads on the lower extremity joints.

Najia Shakoor and Joel A. Block, ARTHRITIS & RHEUMATISM, Vol. 54, No. 9, September 2006, pp 2923–2927

Fatigue Of The Plantar Intrinsic Foot Muscles Increases Navicular Drop

• 21 healthy adults• Surface electromyography of the abductor hallucis muscle was

recorded• The intrinsic foot muscles play a role in support of the medial

longitudinal arch in static stance. Disrupting the function of these muscles through fatigue resulted in an increase in pronation as assessed by navicular drop.

Donella L. Headlee, Jamie L. Leonard, Joseph M. Hart, Christopher D. Ingersoll, Jay Hertel Journal of Electromyography and Kinesiology

Volume 18, Issue 3 , Pages 420-425, June 2008

A Case for Bare Feet

• A high concentration of flat foot among six-year-old children who wore shoes as compared with those who did not, implies that the critical age for development of the arch is before six years.

• Furthermore, optimum foot development occurs in the barefoot environment, and, therefore, children should be encouraged to partake in barefoot activity.

Paul J. Lucas* , Michael M. Berrow, Richard K. Frazine, and Robert A. Neinast

Barefoot To Bedridden

• Barefoot - No Supports 　• Footwear - 4 Supports• Motion Control - 4 Supports• Orthotics - 6 Supports• Orthopedic Shoes and Orthotics - 6 Supports• Cane - 7 Supports• 4-Prong Walker - 10 Supports• Wheel Chair - 4 Wheels• Bedridden

What is Human Spring

Bob Beamon World Record Long Jump

HUMAN SPRING THEORY1. The human spring stores mechanical potential energy

therefore it is an efficiency mechanism.

2. The human spring absorbs forces of landings therefore it is a protective mechanism.

3. The human spring allows the foot to land on uneven surfaces adjusting the body mechanics to the terrain.

4. The human spring is integrated into the biomechanics therefore it is essential for stress/strain free motion

Weakness or locking of the spring can lead to

fatigue, increased risk for acute injury, inability to

heal and accelerated aging of the body’s systems.

Elastic or Spring Energy

• In the elastic-like bounce of the body at each running step the muscle-tendon units are stretched after landing and recoil before take-off.

• Evidence has been provided suggesting that muscle is kept quasi-isometric with the consequence that the length change of the muscle–tendon unit is mostly sustained by tendons

• It has been found that much of the muscle activity in running is associated with tensioning of the tendons, which thereby store energy for successful cycles of movement

• Isometric conntractions are considerably less expensive than dynamic contractions

J Exp Biol. 2006 Oct;209(Pt 20):4051-60.Cavagna GA Istituto di Fisiologia Umana, Università degli Studi di Milano, Via Mangiagalli, 32, 20133 Milan, Italy

Eccentric vs Concentric Training

• An eccentric contraction refers to muscle action winch the muscle force succumbs to the imposed load and the muscle complex lengthens. Not only is it metabolically much more efficient than concentric contraction, but it’s also capable of generating higher forces (Kaneko 1984)  (Komi 1973)  (Rodgers And Berger 1974)

 

• In addition this difference between concentric and eccentric contractions has been found to depend on the velocity of contraction (Komi 1973)

 

•  As the velocity of contraction increases, so do those maximums eccentric force increase whereas the maximum concentric force decreases even though the corresponding EMG for the given muscle group remains reasonably constant.

Kaneko 1984)  (Komi 1973)  (Rodgers And Berger 1974)

WHAT SURFACES ARE BEST FOR BAREFOOT RUNNING

• On the stiffest surfaces, the legs compressed in early stance and then extended in late stance in the pattern that is typical for normal bouncing gaits.

• On the softest surfaces, however, subjects reversed this pattern so that the legs extended up to 8 cm in early stance and then compressed by a similar distance in late stance. Consequently, the center of mass moved downward during stance by 5-7 cm less than the surface compressed and by a similar distance as on the stiffest surfaces.

• This unique leg action probably reduced extensor muscle pre-stretch because the joints first extended and then flexed during stance. This interpretation is supported by the observation that hoppers increased muscle activation by 50% on the softest surface despite similar joint moments and mechanical leg work as on the stiffest surface.

• Thus, the extreme adjustment to leg mechanics for very soft surfaces helps maintain normal center of mass dynamics but requires high muscle activation levels due to the loss of the normal extensor muscle stretch-shorten cycle.

Moritz CT, Farley CT, J Exp Biol. 2005 Mar;208(Pt 5):939-49. Human hopping on very soft elastic surfaces: implications for muscle pre-stretch and elastic energy storage in locomotion.

HUMAN SPRING

Spring Mechanics - Hookes Law

Running Injuries

Most important is the ability of the spring suspension system to

handle the force of the landings

What To Consider When Evaluating Injuries

The development of strength–endurance is a an inherent characteristic and the fundamental principle of training for developing general endurance. Training for strength–endurance is determined predominantly by:

• 

•The magnitude of the load

•The rest interval between training sessions

•The length of the training period

•Additional levels of strength–endurance of the athlete

•The kinesiological structure of the movement

•Relative involvement of static and dynamic strength–endurance

Mel Siff, Yuri Verhkoshansky, Supertraining, Supertraining International Denver USA 1999

ELASTIC DEFORMITY

This type of deformation is reversible. Once the forces are no longer applied, the object returns to its original shape.

The ability of the spring to deform, store energy, reform to its exact original shape, releasing energy.

THE ABILITY OF THE SPRING TO DEFORM, STORE ENERGY, REFORM TO ITS EXACT ORIGINAL SHAPE, RELEASING ENERGY

This is the key principle behind aging

Journal of Applied Physics, M. Mooney, September 1940, Volume: 11 Issue 9 Page (s) 582 - 592

PLASTIC DEFORMITYIn physics and materials science, plasticity describes the deformation of a material undergoing non-reversable changes of the shape in response to applied forces.

The human spring deforms, stores energy, does not return to its exact original shape, releases less energy.

ENERGY, DOES NOT RETURN TO ITS EXACT ORIGINAL SHAPE, RELEASES LESS ENERGY

J. Lubliner, 2008, Plasticity theory, Dover, ISBN 0-486-46290-0, ISBN 978-0-486-46290-5.

ELASTIC DEFORMITY VS

PLASTIC DEFORMITY

YIELD STRENGTH

• Beyond the elastic limit, permanent deformation will occur.

• The lowest stress at which permanent deformation can be measured.

G. Dieter, Mechanical Metallurgy, McGraw-Hill, 1986

Flinn, Richard A.; Trojan, Paul K. (1975). Engineering Materials and their Applications. Boston: Houghton Mifflin Company. p. 61. ISBN 0-395-18916-0.

Plastic Deformity

Compressive Forces

Preventive MedicineIs not working

Train the Landings Vs Take OffsSpring Suspension System

•(Frided 1983) found that a centric training to failure produces market increases in eccentric strength–endurance, but minimal changes in concentric strength–endurance.

 

•Since lengthening of muscle complex occurs with the centric contraction the stretching SEC series elastic component is exposed to greater strain than under concentric conditions and the potential for increase of injury. Thus it is not surprising to learn that most muscle strains and ruptures occur during the Eccentric phase of movement  (Garrett 1986)

Friden J,,,, Seger J, Sjostrom M & Ekblom B 1983a Adaptive Response in Human Skeletal Muscle Subjected to Prolonged Eccentric Training Int J Sports Med 4(3): 177-176

Garrett W (1986) Basic science of musculotendonous injuries In Nicholas J & Hershman E (eds) The Lower Extremity and Spine in Sports & Exercise CV Mosby Co, St Louis : 42-58

GAIT ANAYSIS

COMPENSATING MOTION

UNDERSTANDING THE DYNAMICS OF HUMAN SPRING

BREAKDOWN OF THE IMPACT PROTECTION AND ENERGY RECYCLING

MECHANISMS

• Pain and accelerated ageing

• Silent inflammation• Wear and tear• Stress and strain• Compensating

abnormal movement• Drop and lock of the

spring mechanism• Weakness in spring

suspension system

Reduction in Spring Elastic Capacity of Collagenous Tissues with Age

• Aging reveals changes in collagenous tissues similar to those caused by immobilization with reduction in strength and stiffness of ligaments occurring with advanced age.

• These changes may need you not only to the degenerative process, but also to reduce physical activity, superimpose disease states and other undefined processes (Frankel V & Nordin M 1980)

• Adaptation occurs more slowly and connective tissue such as tendons and ligaments that in muscle and any increase tension may possible in the muscle tenderness complexes by the increased muscle mass can cause damage to these structures (Zalessky & Burkhanov 1981) the US.

• Thus extensive hypertrophy usually leads to slower muscle recovery after exercise, deterioration and speed, speed–strength and speed as well as an increased incidence of injury.

Frankel V & Nordin M 1980 Basic Biomechanics of the Skeletal System Lee & Febiger Zalesky M & Burkhanov A (19810 Muscle Condition and work capacity in track and field athletes

Legkaya Athletika 1: 1-7

LANDING MUSCLESSPRING SUSPENSION SYSTEM MUSCLES

LANDING MUSCLESSPRING SUSPENSION SYSTEM MUSCLES

• Temporary tendon energy storage led to a significant reduction in muscle fascicle lengthening velocity and the rate of energy absorption. We conclude that tendons function as power attenuators that probably protect muscles against damage from rapid and forceful lengthening during energy dissipation.

• For tendon springs to operate effectively, their mechanical properties must be matched to their function.

• For elastic mechanisms is tendon stiffness, and there is increasing evidence that the stiffness of a tendon is ‘tuned’ by remodeling to allow for the effective operation of the muscle–tendon-load system. Several studies have now documented significant increases in tendon stiffness in response to long-term exercise

Proc Biol Sci. 2012 Mar 22;279(1731):1108-13. Epub 2011 Sep 28.Konow N, Azizi E, Roberts TJ. Source Department of Ecology and Evolutionary Biology, Brown University,

J Appl Physiol. 2001 Jan;90(1):164-71.Effects of long-term exercise on the biomechanical properties of the Achilles tendon of guinea fowl

Connective Tissue Strength vs Muscle Strength

• More over, muscle tissue adapts to increase loading within several days

• Connective tissue such as tendons ligaments and joints and bones or systems which contain a high proportion of connective tissue such as bone and cartilage only display significant adaptation and hypertrophy after several weeks or months of progressive loading

• It is vital that the prescription of training takes into account the different rates of adaptation of all systems involved and avoids overtraining systems with the lowest rates of adaptation.

• Gradual increase in training load and avoidance of impulse or explosive methods is essential for minimizing the occurrence of connective tissue soreness and injury,

McDonagh and Davis 1984

Free Stored Elastic Energy

The ability to use stored elastic energy depends on the

•The velocity of stretching•the magnitude of the stretch •the duration of the transition between the termination of the eccentric and initiation of the concentric phase of the movement.

This delay between the two phases should be minimal or the stored elastic energy will be rapidly dissipated.

Because a more prolonged delay will allow fewer cross bridges to remain attached after the stretch (Edman Et Al 1976)

The greater the velocity of stretching it during the eccentric contraction, the greater the storage of elastic energy (Rack & Westbury 1974)

LEVELS OF SILENT VS PAINFUL

INFLAMMATION

Causes of Weakness in the

Human Spring Suspension System

Nature January 2010 Lieberman et al., Nature, 463: 531-565

Scientists have found that people who run barefoot, or in minimal footwear, tend to avoid Heel-striking, and instead land on the ball of the foot or the middle of the foot. In so doing, these runners use the architecture of the foot and leg and some clever Newtonian physics to avoid hurtful and potentially damaging impacts, equivalent to two to three times body weight, that shod heel-strikers repeatedly experience.

People who don’t wear shoes when they run have an astonishingly different strike.

By landing on the middle or front of the foot, barefoot runners have almost no impact collision, much less than most shod runners generate when they heel-strike.

Most people today think barefoot running is dangerous and hurts, but actually you can run barefoot on the world’s hardest surfaces without the slightest discomfort and pain. All you need is a few calluses to avoid roughing up the skin of the foot. Further, it might be less injurious than the way some people run in shoes.

Daniel　E　Lieberman,　a　professor　in　Harvard's　new　department　of　human　evolutionary　biology

Modern society has changed forcing us to wear shoes causing weakness

Modern conveniences have taken the hunt out of our daily routine

causing weakness

Static Evaluation

Patients Don’t Think They Have an Abnormal Gait

GAIT ANAYSIS

Inserts can Interfere with Spring Loading

Steps to Increasing Impact Protection and Energy Recycling

•Release The Abnormal Internal Compressive Force On The Human Spring •Increase Depth Of Loading Of Forces Into The Human Spring•Strengthen The Spring Suspension System via Lever Strengthening•Strengthen The Spring Suspension System via Spring Strengthening•Maintain

STEP ONE

Release The Abnormal Internal Compressive Force

On The Human Spring

Treatment of Muscle Spasms that Preload the Spring Protection and Energy Recycling Mechanisms

• Muscle spindles which detect changes in muscle fiber length and rate of change of length.

 • Golgi tendon organs which monitor the tension and muscle

tendon during muscle contraction or stretching

Release The Abnormal Internal Compressive Force Tonic Protective Muscle Spasm Tension Release

Release The Abnormal Internal Compressive Force Tonic Protective Muscle Spasm Tension ReleaseVibration Therapy

Release The Abnormal Internal Compressive ForceJoint Play Release

Increase Depth Of Loading Of Forces Into The Human Spring

• Dynamic Plyometric-Impact Stretching• Plyometric impulsive stretching, which involves rapid

termination of eccentric loading followed by a brief isometric phase and an explosive rebound belying and stored elastic energy and powerful reflex muscle contraction.

• This stretch shortening action is not intended to increase range of motion, but to use specific stretching phenomena and to increase speed strength of movement for a specific sporting purpose.

Mel Siff, Yuri Verhkoshansky, Supertraining, Supertraining International Denver USA 1999

Current Standard of Care

Relax to Maximize Depth of Safe Loading Elastic Spring Elements to do the Work

• The ability to relax muscle is very important for rapid movements especially in cyclical actions, which involve recent assists of ATP during the phases between muscle contractions.

• The adequate retrieval of elastic energy stored in the muscle complex, together with the stretch–shortening potential of force output, or valuable prerequisites for efficient high velocity cyclic and acyclic movement.

• Verhkoshanski 1996 reports that economical sprinting activity can result in the recovery of about 60% of total mechanical energy expended in the movement cycle, with the remaining 40% being

• He had set a high correlation between the muscular capacity to store potential elastic energy and the performance of distance runners, with an increase in the contribution from non-metabolic energy sources taking place with increased in running velocity

Verkhoshansky YV (1996) Quickness and velocity in sports movements IAAF Quarterly New Studies in Athletics 11 (2-3); 29-37

STEP TWO

STRENGTHEN THE HUMAN SPRING LEVER SYSTEM

RESISTANCE EXERCISES SPRING SUSPENSION MUSCLES

LEVER EXERCISERESISTANCE EXERCISE

STEP THREE

STRENGTHEN THE HUMAN SPRING SPRING SYSTEM

BAREFOOT RUNNINGJUMPING DRILLSPLOMETRICS

Multi-Directional BAREFOOT TrainingCircle Runs – Zig Zag Runs – Side Shuffle

Running-Related Injury Prevention through Barefoot Adaptations

•It is hypothesized that the adaptations which produce shock absorption, an inherent consequence of barefoot activity and a mechanism responsible for the low injury frequency in unshod populations, are related to deflection of the medial longitudinal arch of the foot on loading. •It is also hypothesized that the known inability of this arch of the shod foot to deflect without failure (foot rigidity) is responsible for the high injury frequency in shod populations. •To evaluate these hypotheses, 17 recreational runners were analyzed to study the adaptive pattern of the medial longitudinal arch of the foot due to increased barefoot weight-bearing activity. •Changes occurred in the medial longitudinal arch which allowed deflection of this arch on loading which substantiated the hypotheses. •Other evidence suggests that sensory feedback largely from the glabrous epithelium of the foot is the element of barefoot activity which induced these adaptations. •The sensory insulation inherent in the modern running shoe appears responsible for the high injury frequency associated with running. The injuries are considered "pseudo-neuropathic" in nature.

Medicine in Science and Sports and Exercise 1987 April 18 (2) 148-56

There is a gap in the way doctors think and do and what athletes and patients require for top

performance

RETRAINING ABNORMAL MOVEMENT PATTERNS

RUNNING-WALKING FORM & TECHNIQUE

TRAINING INVOLVES REPEATED MOVEMENTS TO STORE PATTERNS

BANG AND TWIST WALKING VS

SPRING AND ROLL WALKING

DECELERATION LANDING

NEUTRAL LANDING

ACCELERATION LANDING

Old men running: mechanical work and elastic bounce

• The results support the working hypothesis that the impaired muscle function in the old subjects results in a smaller amplitude of the vertical oscillation of the centre of mass, with a lower upward acceleration and a reduced duration of the aerial phase.

• These in turn imply:

– (i) less elastic energy stored

– (ii) a higher step frequency

– (iii) a lower external work to maintain the motion of the centre of mass of the body relative to the surroundings, and

– (iv) a greater internal work to accelerate the limbs relative to the centre of mass.

Proc Biol Sci. 2008 February 22; 275(1633): 411–418. GA Cavagna M.A. Legramandi LA Peyre-Tartaruga

Second Toe Towards The Target

Thank you!