Terrestrial locomotion Terrestrial locomotion has evolution, evolved as animals adapted from ecoregion#Marine, aquatic to ecoregion#Terrestrial, terrestrial environments. Animal locomotion, Locomotion on land raises different problems than that in water, with reduced f ...

by means of a running

gait Gait is the pattern of Motion (physics), movement of the limb (anatomy), limbs of animals, including Gait (human), humans, during Animal locomotion, locomotion over a solid substrate. Most animals use a variety of gaits, selecting gait based on s ...

can be accomplished on level surfaces. However, in most outdoor environments an individual will experience terrain undulations requiring uphill

running Running is a method of terrestrial locomotion by which humans and other animals move quickly on foot. Running is a gait with an aerial phase in which all feet are above the ground (though there are exceptions). This is in contrast to walkin ...

. Similar conditions can be mimicked in a controlled environment on a

treadmill A treadmill is a device generally used for walking, running, or climbing while staying in the same place. Treadmills were introduced before the development of powered machines to harness the power of animals or humans to do work, often a type of ...

also. Additionally, running on inclines is used by runners, both

distance Distance is a numerical or occasionally qualitative measurement of how far apart objects, points, people, or ideas are. In physics or everyday usage, distance may refer to a physical length or an estimation based on other criteria (e.g. "two co ...

and sprinter, to improve cardiovascular conditioning and lower limb strength.

Gait

One complete

cycle is defined as beginning when one foot comes into contact with the ground and continuing until that same foot contacts the ground again. The gait cycle can be further broken down into a number of component parts. Running, by definition, involves a maximum of one foot in contact with the ground at any given time and often no contact with the ground. When the foot is in contact with the ground it is referred to as the “stance phase”. The “aerial phase” is the period between

contralateral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

foot contacts when the body is airborne. For one specific leg, the time of toe-off until subsequent heel contact is known as the “swing-phase” for that leg. One complete gait cycle involves a stance and swing phase for each leg. Running is characterized as a “bouncing gait” rather than the

inverted pendulum An inverted pendulum is a pendulum that has its center of mass above its Lever, pivot point. It is unstable equilibrium, unstable and falls over without additional help. It can be suspended stably in this inverted position by using a control s ...

mechanism of walking. The stance phase of running can be sub-divided into two parts; during the first half energy is used to perform the negative

work Work may refer to: * Work (human activity), intentional activity people perform to support themselves, others, or the community ** Manual labour, physical work done by humans ** House work, housework, or homemaking ** Working animal, an ani ...

of both slowing and lowering the center of mass. In the second half of the stance phase energy is used to perform positive work to lift and accelerate the body. Because of the synchrony of the fluctuations of

kinetic energy In physics, the kinetic energy of an object is the form of energy that it possesses due to its motion. In classical mechanics, the kinetic energy of a non-rotating object of mass ''m'' traveling at a speed ''v'' is \fracmv^2.Resnick, Rober ...

and

gravitational potential energy Gravitational energy or gravitational potential energy is the potential energy an object with mass has due to the gravitational potential of its position in a gravitational field. Mathematically, it is the minimum Work (physics), mechanical work t ...

experienced by the center of mass, mechanical work during running is performed by optimizing the combination of conserved elastic energy in tendons from lengthening and muscle contraction.

Kinematics

Kinematics In physics, kinematics studies the geometrical aspects of motion of physical objects independent of forces that set them in motion. Constrained motion such as linked machine parts are also described as kinematics. Kinematics is concerned with s ...

of running is concerned with describing the motion of the body and in particular the joint angles realized at the hip, knee, and ankle. In level running the hip reaches maximal flexion prior to the end of the swing phase, followed by extension as the leg moves to meet the ground. Throughout stance phase the hip is extending until toe-off to provide propulsion. Knee joint angle displays a biphasic plot. At initial ground contact the knee flexes to lower the body followed by extending to propel the body. Maximal extension is reached at toe-off, after which the knee again flexes to provide clearance. At the ankle maximal

plantarflexion Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative ...

is reached at toe-off and is followed by

dorsiflexion Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

until mid-swing when the ankle of dorsiflexion remains nearly constant until initial ground contact is made and further dorsiflexion occurs to lower and support the body. In the second half of the stance phase the ankle begin rapid plantar flexion until toe-off. A number of studies have been performed examining the kinematics of incline running. Swanson and Caldwell (2000) found greater joint flexion at all three joints during initial foot-strike. Also noted was an increase in extensor range of motion and angular velocity at all three joints during push off. Conversely, Klein et al. had found no changes in joint angles when running on an incline versus level surfaces. However, his subjects ran at a speed equal to

anaerobic threshold Lactate inflection point (LIP) is the exercise intensity at which the blood concentration of lactate and/or lactic acid begins to increase rapidly. It is often expressed as 85% of maximum heart rate or 75% of maximum oxygen intake. When exercisin ...

(average of 3.5 meters/second) that was significantly slower than the subjects in Swanson and Caldwell’s study (4.5 meters/second). Also, grade was 5% in contrast to 30%.

Stride Frequency and Length

When running at a constant speed, it has been found that stride frequency increases during incline vs. level running with a concomitant decrease in stride length. At a speed of 30 meters/second Gottschall and Kram noted an increase in stride frequency from 1.45±0.06 Hz to 1.51±0.07 Hz at an incline of 9 degrees (15.8%). Telhan et al. validated this finding at a constant speed of 3.13 meters/second and a gradient of 4 degrees (6.98%) when they observed an increase in frequency from 168.5±8.1 steps/minute to 170.5±7.9 steps/minute. Both studies also saw significant decreases in stride length when running on an incline as compared to level running. The previous studies occurred at moderate speeds. When running

velocity Velocity is a measurement of speed in a certain direction of motion. It is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of physical objects. Velocity is a vector (geometry), vector Physical q ...

is increased 4.5 meters/second and grade increased to 30%, the same trends of increasing stride frequency and decreasing stride length are seen.

Muscle Activation

The quadriceps femoris muscle group and rectus femoris are both responsible for knee extension while the rectus femoris also contributes to flexion at the hip. Electromyographic (EMG) data has shown both to be active in anticipation of and during stance phase to support the body. The rectus femoris is also active in mid-swing phase as a result of its hip flexor capabilities. The major

antagonist An antagonist is a character in a story who is presented as the main enemy or rival of the protagonist and is often depicted as a villain. During incline running increases in activation of the rectus femoris and gastrocnemius were noted by Cai. Yokozawa found incline running to produce increased activation in the vasti group, hamstrings, iliopsoas, and adductors. Neither of these two provided timing on what point of gait these increases occurred. Swanson also recorded EMG data, but compared differences before foot strike (swing phase) and after foot strike (stance phase) as well as on a wider range of muscles. Results showed significant increases in activation of tibialis anterior, gastrocnemius, soleus, rectus femoris, vastus lateralis, medial hamstring, biceps femoris, and gluteus maximus before foot strike. Following foot strike increases were seen in all muscles with the exception of the tibialis anterior and medial hamstring.

Kinetics

The kinetics of running, similar to the kinematics, is used to describe the motion of the body. However, in contrast to kinematics, kinetics also takes into account the relationship between motion and the

force In physics, a force is an influence that can cause an Physical object, object to change its velocity unless counterbalanced by other forces. In mechanics, force makes ideas like 'pushing' or 'pulling' mathematically precise. Because the Magnitu ...

s and

torque In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force (also abbreviated to moment). The symbol for torque is typically \boldsymbol\tau, the lowercase Greek letter ''tau''. Wh ...

s the causing it. These are expressed as joint moments and torques. Telhan et al. observed no change in the joint moments at the hip, knee, or ankle when comparing incline to level running. Also noted was the fact that both general kinetic patterns and peak magnitudes at all three joints were consistent with those in the current literature. The only significant change between the two conditions was an increase in the hip power at early stance phase. In contrast, Yokozawa saw increases in support phase knee and hip torques at the rectus femoris, hypothesizing it as a compensation mechanism for the decreased knee extension torque at the vasti set. Also seen was an increase in the net hip flexion torque during the recovery phase of incline running, allowing a quicker recovery and allowing a greater amount of hip flexion.

Ground Reaction Forces

Ground reaction forces (GRF) are exerted by the ground on the body in contact with it and reflect the body’s acceleration. During level running, ground reaction forces can be dichotomized into vertical ground reaction forces and horizontal ground reaction forces. In the comparison of incline to level running, the terms normal and parallel ground reaction forces are substituted for vertical and horizontal because when running on an incline the latter terms become inaccurate in describing the direction of force application. Measurements are expressed as a percentage of body weight, where a value of one body weight is the force exerted to support the body when standing. A plot of normal GRF is characterized by its biphasic nature, with an initial impact peak corresponding to the braking portion of the stance phase (heal strike) followed by a larger peak representing the propulsion part of the stance phase (toe off). Typical parallel GRF application during running involves two peaks, one that is negative during breaking and one that is positive during propulsion. Important characteristics of a GRF plot are the magnitude of the peaks (impact and active), the rate of loading, average force, and the total area under the plot. During level running at a speed of 3meters per second the vertical ground reaction force reaches a peak of approximately 2.5 times body weight. Data on normal GRF during incline running has been sparse because of challenges in force platform construction. Gottschall and Kram (2004) mounted a force treadmill on wedges of varying inclines and found that compared to level running, the initial impact peak was decreased at 3, 6, and 9 degrees of inline. They also found that the braking parallel GRF was absent at 9 degrees of incline in addition to a 75% increase in the propulsive parallel GRF. Tehlan, however, did not find a blunted impact peak with incline running at 4 degrees.

References

Farley, Claire T., and Daniel P. Ferris. “Biomechanics of Walking and Running: Center of mass Movements to Muscle Action.” Biomechanics of Walking and Running. 253-284. Print.Gottschall, J.S., and Kram, R. “Ground reaction forces during downhill and uphill running.” Journal of Biomechanics. 38 (2005): 445-452. Print.Swanson, S.C., and Caldwell, G.E. “An integrated biomechanical analysis of high speed incline and level treadmill running.” Medicine & Science in Sports & Exercise. 32.6 (2000): 1146-1155. Print.Telhan, G., et al. “Lower Limb Joint Kinetics During Moderately Sloped Running.” Journal of Athletics Training. 45.1 (2010): 16-21. Print.Tulloh, B. “The role of cross-country in the development of a runner.” New Studies in Athletics. 13 (1998): 9-11. Print.Yokozawa, T., Fujii, N., Ae, M. “Muscle activities of the lower limb during level and uphill running.” Journal of Biomechanics. 40 (2007): 3467-3475. Print.Klein, M.R., et al. “Metabolic and biomechanical variables of two incline conditions during distance running.” Medicine & Science in Sports & Exercise. 29.12 (1997): 1625-1630. Print.Cai, Zong-Yan, et al. “Comparison of lower limb muscle activation during downhill, level and uphill running.” Isokinetics and Exercise Science. 18 (2010) 163-168. Print.Novacheck, Tom F. “The biomechanics of running.” Gait and Posture. 7 (1998): 77-95.Cavanagh, Peter R. Biomechanics of distance running. Champaign, IL: Human Kinetics, 1990. Print.Lichtwark, G.A., Bougoulias, K., Wilson, A.M. “Muscicle fascicle and series elastic element length changes along the length of the human gastrocnemius during walking and running.” Journal of Biomechanics. 40 (2007): 157-164. Print. Running by type Terrestrial locomotion