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PubMed1989

Ground reaction forces at different speeds of human walking and running.

In this study the variation in ground reaction force parameters was investigated with respect to adaptations to speed and mode of progression, and to type of foot-strike. Twelve healthy male subjects were studied during walking (1.0-3.0 m s-1) and running (1.5-6.0 m s-1). The subjects were selected with respect to foot-strike pattern during running. Six subjects were classified as rearfoot strikers and six as forefoot strikers. Constant speeds were accomplished by pacer lights beside an indoor straightway and controlled by means of a photo-electronic device. The vertical, anteroposterior and mediolateral force components were recorded with a force platform. Computer software was used to calculate durations, amplitudes and impulses of the reaction forces. The amplitudes were normalized with respect to body weight (b.w.). Increased speed was accompanied by shorter force periods and larger peak forces. The peak amplitude of the vertical reaction force in walking and running increased with speed from approximately 1.0 to 1.5 b.w. and 2.0 to 2.9 b.w. respectively. The anteroposterior peak force and mediolateral peak-to-peak force increased about 2 times with speed in walking and about 2-4 times in running (the absolute values were on average about 10 times smaller than the vertical). The transition from walking to running resulted in a shorter support phase duration and a change in the shape of the vertical reaction force curve. The vertical peak force increased whereas the vertical impulse and the anteroposterior impulses and peak forces decreased. In running the vertical force showed an impact peak at touch-down among the rearfoot strikers but generally not among the forefoot strikers. The first mediolateral force peak was laterally directed (as in walking) for the rearfoot strikers but medially for the forefoot strikers. Thus, there is a change with speed in the complex interaction between vertical and horizontal forces needed for propulsion and equilibrium during human locomotion. The differences present between walking and running are consequences of fundamental differences in motor strategies between the two major forms of human progression.

Adaptation, Physiological↗

PubMed2002

Relationship between velocity and temporal variables of the flat shod running walk.

The running walk of the Tennessee Walking Horse is often described as a faster variation of the walk, indicating the importance of velocity on the mechanics of the gait. Variations in gait variables create difficulties in clearly identifying the normal and abnormal running walk in a clinical evaluation. The objectives of this study were, therefore, to describe the flat shod running walk and to determine the relationship between velocity and the running walk. From frame-by-frame analysis of 60 Hz film, temporal variables were averaged for 6 strides from 6 horses performing an 'easy' (slow) and 'strong' (fast) running walk during a flat shod, easy-rider Tennessee Walking Horse show class. The running walk at both velocities was a 4-beat, symmetrical stepping gait with a lateral footfall sequence and lateral couplets. The velocity ranged from mean +/- s.d. 2.66 +/- 0.34 to 3.80 +/- 0.18 m/s. For both velocities (slow, fast), hind stance as a percentage of stride duration (58 +/- 3%, 56 +/- 2%) was significantly longer than fore (51 +/- 5%, 48 +/- 1%); diagonal advanced placement (29 +/- 2%, 37 +/- 4%) and lift-off (35 +/- 5%, 39 +/- 2%) were significantly longer than lateral (advanced placement: 22 +/- 2%, 12 +/- 3%; lift-off: 18 +/- 4%, 10 +/- 2); and lateral bipedal support (50 +/- 9%, 67 +/- 7%) was significantly longer than diagonal (27 +/- 6%, 16 +/- 4%). Strong correlations were found between velocity and diagonal advanced placement (0.640), lateral lift-off (-0.924) and diagonal (-0.648) and lateral (0.904) bipedal support. Understanding the running walk and the gait variations due to velocity may be important to both the performance and soundness of the Tennessee Walking Horse.

Animals↗

PubMed2006

Immunoglobulin responses to a repeated bout of downhill running.

OBJECTIVE: To examine the effect of downhill running on immunoglobulin responses. METHOD: Eleven untrained men performed 2 x 60 minute bouts of downhill running (-13.5% gradient), at a speed eliciting 75% of their vO2peak on a level grade. Two runs were spaced 14 days apart. Serum samples were collected before, after, and every hour for 12 hours and every 24 hours for six days. Serum total creatine kinase and immunoglobulin isotypes and subclasses were measured, and results were analysed using a repeated measures analysis of variance (12 hour period, 2 x 14; 24 hour intervals, 2 x 6, p < or = 0.05). RESULTS: There was a significant interaction effect for creatine kinase (activity lower after run 2 than after run 1, 6-24 h) and exercise effect, with the serum concentrations of IgG1, IgG2, IgG4, and IgE lower, and IgM higher, after run 2. CONCLUSION: Lower concentrations of IgG1, IgG2, and IgE after run 2 may reflect a dampened autoimmune inflammatory response to autoantigens and enhanced autoantigen clearance mediated by the upregulation of IgM.

Adolescent↗

PubMed1987

The effects of maximum steady state pace training on running performance.

Maximum aerobic power (VO2 max), maximum anaerobic power (AP max), submaximal exercise heart rate (HRsub), and performance times for distances of 15m, 600 m, 3.22 km, and 10 km were evaluated in 12 male runners prior to and after 7 weeks of a running programme at each individual's maximum steady-state (MSS) pace. MSS pace, a running speed at which blood lactate is believed to equal 2.2 mmol . l-1, was calculated from weekly 3.22 km runs utilising the regression equation of LaFontaine et al (1981). During the training period, the mean MSS pace increased 11.3% from 3.76 to 4.19 m.s.-1. Body weight and maximal exercise heart rate were unaffected by MSS training. However, MSS training was associated with increases (p less than 0.05) in absolute VO2 max (8.9%) and VO2 max relative to body weight (8.1%), absolute AP max (3.7%) and AP max, relative to body weight (4.3%); decreases in resting HR (5.4%) and HRsub (6.9%); and decreases in performance times for runs of 15m (1.8%), 600 m (4.4%), 3.22 km (9.6%), and 10 km (12.1%). MSS paces determined prior to the pre- and post-training 10 km races were significantly related to the pre-training (r = 0.98) and post-training 10 km (r = 0.95) performance paces. Pretraining MSS pace, maximal aerobic power, and performance times for the 3.22 km and 10 km distances were highly related to improvements in MSS pace and performance times for the 3.22 km and 10 km runs. Our findings indicate that training at MSS pace is an effective method to increase maximal aerobic and anaerobic power, and decrease performance times for short- and middle-distance running events. Pre-training running performance may predict the magnitude of improvement due to MSS pace training.

Adult↗

PubMed1998

Ratings of perceived exertion to determine intensity during outdoor running.

A paucity of data exists related to the usefulness of Ratings of Perceived Exertion (RPE) to set exercise intensity in non-laboratory settings. The purpose of this study was to determine if RPE could be used on an outdoor track to generate blood lactate and heart rate (HR) responses similar to those obtained on a treadmill (tm) run. Nine experienced runners (6 males, 3 females; VO2peak = 56.2 +/- 6.7 ml.kg-1.min-1) completed a horizontal, incremental tm test. HR, RPE, and lactate were measured for each stage. Subsequently, subjects ran for 30 min on an outdoor track at the RPE corresponding with 2.5 mM lactate during the tm run. Repeated measures ANOVA compared lactate and HR values at 2.5 mM lactate on the tm run and values obtained during the track run. Lactate during the track run was significantly higher (p < .05) than 2.5 mM throughout the 30 min (6.9 +/- 2.9, 6.3 +/- 2.9, and 5.8 +/- 3.0 mM at 10, 20, and 30 min, respectively). HR at 2.5 mM lactate during the tm run (173 +/- 6.1 bpm) was significantly lower (p < .05) than at min 10 and 20 of the track run (182.6 +/- 9.3 and 182.9 +/- 8.0 bpm, respectively) but not different from min 30 (181.3 +/- 10.6 bpm). In summary, it is difficult to generate specific physiological responses using RPE.

Adult↗

PubMed2004

Energetics of high-speed running: integrating classical theory and contemporary observations.

We hypothesized that the anaerobic power and aerobic power outputs during all-out runs of any common duration between 10 and 150 s would be proportional to the maximum anaerobic (E(an-max)) and aerobic powers (E(aer-max)) available to the individual runner. Seventeen runners who differed in E(an-max) and E(aer-max) (5 sprinters, 5 middle-distance runners, and 7 long distance runners) were tested during treadmill running on a 4.6 degrees incline. E(an-max) was estimated from the fastest treadmill speed subjects could attain for eight steps. E(aer-max) was determined from a progressive, discontinuous, treadmill test to failure. Oxygen deficits and rates of uptake were measured to assess the respective anaerobic and aerobic power outputs during 11-16 all-out treadmill runs that elicited failure between 10 and 220 s. We found that, during all-out runs of any common duration, the relative anaerobic and aerobic powers utilized were largely the same for sprint, middle-distance, and long-distance subjects. The similar fractional utilization of the E(an-max) and E(aer-max) available during high-speed running 1) provides empirical values that modify and advance classic theory, 2) allows rates of anaerobic and aerobic energy release to be quantified from individual maxima and run durations, and 3) explains why the high-speed running performances of different event specialists can be accurately predicted (R(2) = 0.97; n = 254) from two direct measurements and the same exponential time constant.

Adult↗

PubMed1987

Groucho running.

An important determinant of the mechanics of running is the effective vertical stiffness of the body. This stiffness increases with running speed. At any one speed, the stiffness may be reduced in a controlled fashion by running with the knees bent more than usual. In a series of experiments, subjects ran in both normal and flexed postures on a treadmill. In other experiments, they ran down a runway and over a force platform. Results show that running with the knees bent reduces the effective vertical stiffness and diminishes the transmission of mechanical shock from the foot to the skull but requires an increase of as much as 50% in the rate of O2 consumption. A new dimensionless parameter (u omega 0/g) is introduced to distinguish between hard and soft running modes. Here, omega 0 is the natural frequency of a mass-spring system representing the body, g is gravity, and u is the vertical landing velocity. In normal running, this parameter is near unity, but in deep-flexed running, where the aerial phase of the stride cycle almost disappears, u omega 0/g approaches zero.

Adult↗

PubMed1992

Accumulated oxygen deficit increases with inclination of uphill running.

This study examined whether accumulated oxygen deficit depends on treadmill grade during uphill running. Oxygen uptake was measured during steady-state submaximal running. By linear extrapolation at each grade, energy demand was estimated for short exhaustive runs. Oxygen deficit was the difference between this estimate and accumulated oxygen uptake. Six subjects ran at grades of 1, 15, and 20% (study I), and five males trained for anaerobic metabolism ran at 1, 10.5, and 15% (study II). Accumulated oxygen deficit was 40 +/- 11 (SD), 72 +/- 20, and 69 +/- 8 ml O2/kg, respectively (study I), and 57 +/- 8, 78 +/- 10, and 100 +/- 7 ml O2/kg (study II). The finding that accumulated oxygen deficit became larger with treadmill inclination could reflect involvement of an increasing muscle mass. However, variation in accumulated oxygen deficit was too large to make this possibility the only explanation. More likely at small treadmill inclinations energy demand for high-intensity running is underestimated by extrapolation from oxygen uptake during submaximal exercise. At high grades of uphill running, accumulated oxygen deficit reached a maximum that may reflect the subjects' anaerobic capacity for running. This hypothesis was substantiated by an enhanced accumulated oxygen deficit in the anaerobically trained subjects during 15%, but not during 1%, uphill running.

Adolescent↗

PubMed1992

Energetics of walking and running: insights from simulated reduced-gravity experiments.

On Earth, a person uses about one-half as much energy to walk a mile as to run a mile. On another planet with lower gravity, would walking still be more economical than running? When people carry weights while they walk or run, energetic cost increases in proportion to the added load. It would seem to follow that if gravity were reduced, energetic cost would decrease in proportion to body weight in both gaits. However, we find that under simulated reduced gravity, the rate of energy consumption decreases in proportion to body weight during running but not during walking. When gravity is reduced by 75%, the rate of energy consumption is reduced by 72% during running but only by 33% during walking. Because reducing gravity decreases the energetic cost much more for running than for walking, walking is not the cheapest way to travel a mile at low levels of gravity. These results suggest that the link between the mechanics of locomotion and energetic cost is fundamentally different for walking and for running.

Energy Metabolism↗

PubMed2004

Muscle mechanical advantage of human walking and running: implications for energy cost.

Muscular forces generated during locomotion depend on an animal's speed, gait, and size and underlie the energy demand to power locomotion. Changes in limb posture affect muscle forces by altering the mechanical advantage of the ground reaction force (R) and therefore the effective mechanical advantage (EMA = r/R, where r is the muscle mechanical advantage) for muscle force production. We used inverse dynamics based on force plate and kinematic recordings of humans as they walked and ran at steady speeds to examine how changes in muscle EMA affect muscle force-generating requirements at these gaits. We found a 68% decrease in knee extensor EMA when humans changed gait from a walk to a run compared with an 18% increase in hip extensor EMA and a 23% increase in ankle extensor EMA. Whereas the knee joint was extended (154-176 degrees) during much of the support phase of walking, its flexed position (134-164 degrees) during running resulted in a 5.2-fold increase in quadriceps impulse (time-integrated force during stance) needed to support body weight on the ground. This increase was associated with a 4.9-fold increase in the ground reaction force moment about the knee. In contrast, extensor impulse decreased 37% (P < 0.05) at the hip and did not change at the ankle when subjects switched from a walk to a run. We conclude that the decrease in limb mechanical advantage (mean limb extensor EMA) and increase in knee extensor impulse during running likely contribute to the higher metabolic cost of transport in running than in walking. The low mechanical advantage in running humans may also explain previous observations of a greater metabolic cost of transport for running humans compared with trotting and galloping quadrupeds of similar size.

Adult↗

PubMed2002

Reduced activity of muscle Na(+)-K(+)-ATPase after prolonged running in rats.

The purpose of this study was to investigate the hypothesis that Na(+)-K(+)-ATPase activity is reduced in muscle of different fiber composition after a single session of aerobic exercise in rats. In one experiment, untrained female Sprague-Dawley rats (weight 275 +/- 21 g; means +/- SE; n = 30) were run (Run) on a treadmill at 21 m/min and 8% grade until fatigue, or to a maximum of 2 h, which served as control (Con), or performed an additional 45 min of low-intensity exercise at 10 m/min (Run+). In a second experiment, utilizing rats of similar characteristics (weight 258 +/- 18 g; n = 32), Run was followed by passive recovery (Rec). Directly after exercise, rats were anesthetized, and tissue was extracted from Soleus (Sol), red vastus lateralis (RV), white vastus lateralis (WV), and extensor digitorum longus (EDL) and frozen for later analysis. 3-O-methylfluorescein phosphatase activity (3-O-MFPase) was determined as an indicator of Na(+)-K(+)-ATPase activity, and glycogen depletion identified recruitment of each muscle during exercise. 3-O-MFPase was decreased (P < 0.05) at Run+ by an average of 12% from Con in all muscles (P < 0.05). No difference was found between Con and Run. Glycogen was lower (P < 0.05) by 65, 57, 44, and 33% (Sol, EDL, RV, and WV, respectively) at Run, and there was no further depletion during the continued low-intensity exercise period. No differences in Na(+)-K(+)-ATPase activity was observed between Con and Rec. The results of this study indicate that inactivation of Na(+)-K(+)-ATPase can be induced by aerobic exercise in a volume-dependent manner and that the inactivation that occurs is not specific to muscles of different fiber-type composition. Inactivation of Na(+)-K(+)-ATPase suggests intrinsic structural modifications by mechanisms that are unclear.

Animals↗

PubMed2003

High-speed running performance: a new approach to assessment and prediction.

We hypothesized that all-out running speeds for efforts lasting from a few seconds to several minutes could be accurately predicted from two measurements: the maximum respective speeds supported by the anaerobic and aerobic powers of the runner. To evaluate our hypothesis, we recruited seven competitive runners of different event specialties and tested them during treadmill and overground running on level surfaces. The maximum speed supported by anaerobic power was determined from the fastest speed that subjects could attain for a burst of eight steps (approximately 3 s or less). The maximum speed supported by aerobic power, or the velocity at maximal oxygen uptake, was determined from a progressive, discontinuous treadmill test to failure. All-out running speeds for trials of 3-240 s were measured during 10-13 constant-speed treadmill runs to failure and 4 track runs at specified distances. Measured values of the maximum speeds supported by anaerobic and aerobic power, in conjunction with an exponential constant, allowed us to predict the speeds of all-out treadmill trials to within an average of 2.5% (R2 = 0.94; n = 84) and track trials to within 3.4% (R2 = 0.86; n = 28). An algorithm using this exponent and only two of the all-out treadmill runs to predict the remaining treadmill trials was nearly as accurate (average = 3.7%; R2 = 0.93; n = 77). We conclude that our technique 1) provides accurate predictions of high-speed running performance in trained runners and 2) offers a performance assessment alternative to existing tests of anaerobic power and capacity.

Exercise↗

PubMed1992

Stabilization of gaze during circular locomotion in darkness. II. Contribution of velocity storage to compensatory eye and head nystagmus in the running monkey.

1. Yaw eye in head (Eh) and head on body velocities (Hb) were measured in two monkeys that ran around the perimeter of a circular platform in darkness. The platform was stationary or could be counterrotated to reduce body velocity in space (Bs) while increasing gait velocity on the platform (Bp). The animals were also rotated while seated in a primate chair at eccentric locations to provide linear and angular accelerations similar to those experienced while running. 2. Both animals had head and eye nystagmus while running in darkness during which slow phase gaze velocity on the body (Gb) partially compensated for body velocity in space (Bs). The eyes, driven by the vestibuloocular reflex (VOR), supplied high-frequency characteristics, bringing Gb up to compensatory levels at the beginning and end of the slow phases. The head provided substantial gaze compensation during the slow phases, probably through the vestibulocollic reflex (VCR). Synchronous eye and head quick phases moved gaze in the direction of running. Head movements occurred consistently only when animals were running. This indicates that active body and limb motion may be essential for inducing the head-eye gaze synergy. 3. Gaze compensation was good when running in both directions in one animal and in one direction in the other animal. The animals had long VOR time constants in these directions. The VOR time constant was short to one side in one animal, and it had poor gaze compensation in this direction. Postlocomotory nystagmus was weaker after running in directions with a long VOR time constant than when the animals were passively rotated in darkness. We infer that velocity storage in the vestibular system had been activated to produce continuous Eh and Hb during running and to counteract postrotatory afterresponses. 4. Continuous compensatory gaze nystagmus was not produced by passive eccentric rotation with the head stabilized or free. This indicates that an aspect of active locomotion, most likely somatosensory feedback, was responsible for activating velocity storage. 5. Nystagmus was compared when an animal ran in darkness and in light. the beat frequency of eye and head nystagmus was lower, and the quick phases were larger in darkness. The duration of head and eye quick phases covaried. Eye quick phases were larger when animals ran in darkness than when they were passively rotated. The maximum velocity and duration of eye quick phases were the same in both conditions. 6. The platform was counterrotated under one monkey in darkness while it ran in the direction of its long vestibular time constant.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation, Physiological↗

PubMed2003

Effects of treadmill running on brain activation and the corticotropin-releasing hormone system.

The present study was conducted to investigate the effects of treadmill running on the corticotropin-releasing hormone (CRH), CRH receptor type 1 (CRH-R1) and CRH-binding protein (CRH-BP) in the brain of rats that were killed either at rest, immediately after 60 min of treadmill running, or 180 min following a 60-min session of intensive exercise. The expression of the neuronal activity marker c-FOS was also determined in the three conditions of this study. The levels of c-FOS mRNA immediately following running were high in the cortex, caudate-putamen, lateral septum, bed nucleus of the stria terminalis, dorsal and medial thalamus, hypothalamus, pontine nuclei, locus coeruleus and hypoglossal nucleus. In most brain regions investigated, excluding the locus coeruleus and the cingulate cortex, c-FOS mRNA expression returned to control levels after 2 h of recovery. The highest concentration of cells co-expressing the protein Fos and CRH mRNA neurons was found in the parvocellular part of the paraventricular nucleus, which also expressed CRH heteronuclear RNA and CRH-R1 mRNA. The medial preoptic area (MPOA), the medial mammillary nucleus and the posterior hypothalamic as well as the somatosensory cortex, the medial geniculate nucleus, the reticulotegmental nucleus, and Barrington's nucleus also co-expressed Fos and CRH mRNA. The expression of CRH-BP gene was induced in the MPOA following running. In summary, the present study demonstrates that treadmill running leads to a strong expression of c-FOS mRNA that is widely distributed throughout the brain. c-FOS mRNA was found in structures of the somatosensory and somatomotor systems, indicating that these regions were activated during exercise. The pattern of distribution of c-FOS mRNA showed similarities with that triggered by neurogenic and systemic stresses. The present results also indicate that treadmill running can strongly activate the hypophysiotropic CRH system, which suggests, in agreement with the pattern of c-FOS mRNA distribution, that treadmill running has a strong stress component.

Animals↗

PubMedDate not supplied

Shock absorption characteristics of running shoes.

The change in shock absorption properties of running shoes was evaluated as a function of miles run. Different models of running shoes encompassing a wide range in retail price were obtained and mechanically tested to simulate the repeated heel strikes of running. The energy absorbed by the shoes was determined from the area under the load deformation curve at the equivalent of 0, 5, 10, 25, 50, 75, 100, 125, 150, 200, 250, 300, and 500 miles of running. Shoes were also tested at similar intervals after having been worn by volunteers during normal training. An approximate 33% difference in the initial shock absorption was observed in the different shoe models. In general, the shoes retained approximately 75% of their initial shock absorption capability after 50 miles of simulated running, and approximately 67% after 100 to 150 miles. Between 250 and 500 miles the shoes retained less than 60% of their initial shock absorption capacity. No differences in shock absorption characteristics were apparent based upon either shoe price or the manufacturer model. The results of shoes tested by the volunteer runners also showed a marked reduction in shock absorption with mileage. The loss, however, was not as great as in the machine-simulated running, with approximately 70% of initial shock absorption retained at 500 miles.

Costs and Cost Analysis↗

PubMed2004

Voluntary running in deer mice: speed, distance, energy costs and temperature effects.

The energetics of terrestrial locomotion are of considerable interest to ecologists and physiologists, but nearly all of our current knowledge comes from animals undergoing forced exercise. To explore patterns of energy use and behavior during voluntary exercise, we developed methods allowing nearly continuous measurements of metabolic rates in freely behaving small mammals, with high temporal resolution over periods of several days. We used this approach to examine relationships between ambient temperature (Ta), locomotor behavior and energy costs in the deer mouse, a small mammal that routinely encounters a large range of temperatures in its natural habitat. We tested for individual consistency in running behavior and metabolic traits, and determined how locomotor costs vary with speed and Ta. Because of the importance of thermoregulatory costs in small mammals, we checked for substitution of exercise heat for thermostatic heat production at Ta below the thermal neutral zone and determined the fraction of the daily energy budget comprising exercise costs. Locomotor behavior was highly variable among individuals but had high repeatability, at least over short intervals. We found few temperature-related changes in speed or distance run, but Ta strongly affected energy costs. Partial substitution of exercise heat for thermogenic heat occurred at low Ta. This reduced energy expenditure during low-temperature running by 23-37%, but running costs comprised a fairly minor fraction of the energy budget, so the daily energy savings via substitution were much smaller. Deer mice did not adjust running speed to maximize metabolic economy, as they seldom used the high speeds that provide the lowest cost of transport. The highest voluntary speeds (4-5 km h(-1)) were almost always below the predicted maximal aerobic speed, and were much less than the species' maximal sprint speed. Maximum voluntarily attained rates of oxygen consumption (VO2) were highest at low Ta, but rarely approached maximal VO2 during forced treadmill exercise. Mean respiratory exchange ratios coincident with maximal voluntary VO2 increased slightly as Ta declined, but were always below 1.0 (another indication that metabolic rate was less than the aerobic maximum). Individuals with high running performance (cumulative distance and running time) had high resting metabolism, which suggests a cost of having high capacity or propensity for activity.

Animals↗

PubMed1998

Determinants of the center of mass trajectory in human walking and running.

Walking is often modeled as an inverted pendulum system in which the center of mass vaults over the rigid stance limb. Running is modeled as a simple spring-mass system in which the center of mass bounces along on the compliant stance limb. In these models, differences in stance-limb behavior lead to nearly opposite patterns of vertical movements of the center of mass in the two gaits. Our goal was to quantify the importance of stance-limb behavior and other factors in determining the trajectory of the center of mass during walking and running. We collected kinematic and force platform data during human walking and running. Virtual stance-limb compression (i.e. reduction in the distance between the point of foot-ground contact and the center of mass during the first half of the stance phase) was only 26% lower for walking (0.091 m) than for running (0.123 m) at speeds near the gait transition speed. In spite of this relatively small difference, the center of mass moved upwards by 0.031 m during the first half of the stance phase during walking and moved downwards by 0.073 m during the first half of the stance phase during running. The most important reason for this difference was that the stance limb swept through a larger angle during walking (30.4 degrees) than during running (19.2 degrees). We conclude that stance-limb touchdown angle and virtual stance-limb compression both play important roles in determining the trajectory of the center of mass and whether a gait is a walk or a run.

Biomechanical Phenomena↗

PubMed1988

Effects of shoe type on cardiorespiratory responses and rearfoot motion during treadmill running.

Running kinematics and physiological responses to high intensity submaximal treadmill running in training shoes and racing flats were evaluated. Eight women (mean age = 21.9 yr) completed a peak VO2 test on the treadmill (mean peak VO2 = 49.2 ml.kg-1.min-1). In two subsequent testing sessions, subjects completed 15-min runs at a speed corresponding to 90% of peak VO2 (range = 9.9-13.4 km.hr-1) while wearing training shoes and racing flats (balanced order assignment). No significant time effect or time by shoe condition interaction was observed for the rearfoot motion variables. Maximum rearfoot angle and total rearfoot motion averaged 42% and 13.9% higher, respectively, for the racing flat (P less than 0.05). There were significant increases over time for VO2, VE, HR, and RPE, indicating an increase in cardiorespiratory response and the perception of effort over the course of the 15-min run. Thus, metabolic and perceptual indications of fatigue at the end of the run emerged but were not accompanied by rearfoot motion changes in either running shoe. These results indicate that rearfoot motion is a function of shoe design and did not change during 15 min of high intensity running.

Adult↗