How does terrain affect running

More: 6 Tips to Tackle Any Terrain. It takes power to get up those hills; including uphill repeats may seem obvious, but not all runners actually do hill work, or they don't mix up the kind of work that they do. Approach hills with a three-pronged approach, similar to your regular running workouts:. Do to meter hill bursts, and allow for full recovery between each repeat. This is your speed session for the week. Complete longer, to 1,meter hill repeats for your endurance-focused interval sessions.

You can also do tempo runs uphill on a treadmill set on a grade if you don't have an actual course. More Running Articles. Look for this banner for recommended activities. Cancel Yes. Join Active or Sign In. All rights reserved. You may shorten your stride when running on an uneven trail, for instance, or lift your feet higher if you're sprinting through tall grass.

Running on different surfaces forces you to practice balance and recruit muscles you might not ordinarily work, says Carl Leivers, a USA Track and Field-certified run coach. From a structural standpoint, he adds, challenging different muscles helps you become a stronger and more well-rounded runner. Varying your terrain is also an important factor in preventing injuries caused by overuse. Running on hard surfaces like concrete places more stress on your bones, she says, whereas running on soft surfaces, like sand or grass, places more stress on tendons.

There are benefits and risks that come with every type of terrain, however. Hamilton agrees. If you're accustomed to running the same path every day, it's best to introduce new surfaces slowly. Start with once a week for one of your shorter or easier runs, Leivers says, then build up gradually if your body can handle it. What terrain you incorporate — and how often — depends on your goals as well. Roads are one of the most popular places to run for two main reasons: they're easily accessible and they provide a smooth, stable running surface.

Roads can be tougher on your joints, though, but you shouldn't avoid them completely, especially if you're training for a road race. If you're gearing up for a road-based marathon or half-marathon in particular, Leivers says you should aim to do 30 percent of your weekly mileage on concrete and asphalt to prepare your body for the pounding and impact.

Dirt trails rank among the more difficult types of terrain to run on, but they're also the most dynamic. Compared to asphalt, dirt is softer, Hamilton says, which means less pounding on your joints. Of course, adjusting your footing to account for roots, rocks, and fallen leaves helps engage and challenge different muscles, but uneven terrain can also be a trip hazard.

Leg stiffness is also likely to change with increased surface height variability. During human reaching in the presence of expected mechanical perturbations Burdet et al. The nervous system may respond to expected lower limb perturbations similarly. In addition, Grimmer et al. However, runners then decrease their leg stiffness for the actual step-up, possibly to smooth out the perturbation to the center of mass trajectory.

It is likely that runners would also adjust leg stiffness in response to running on uneven terrain. In this study, we examined the energetic and biomechanical changes during running on uneven terrain when compared with running on smooth terrain. We used an uneven terrain surface that was attached to a standard exercise treadmill Fig. We hypothesized that, on uneven terrain, subjects would show greater energy expenditure and step parameter variability.

Based on previous research indicating increased limb stiffness under conditions of anticipated mechanical perturbations, we also expected runners to increase leg stiffness on uneven terrain compared with smooth terrain. Our overall objective was to provide insight into how the biomechanical adjustments lead to greater energy expenditure during running on uneven surfaces.

Study apparatus. A Uneven terrain treadmill used for the running studies. B Schematic representation of the uneven surface, with stepping areas of three different heights arrows indicate the treadmill's long axis. C Close-up of the blocks comprising the stepping areas. Dimensions: H, 1. Running on uneven terrain resulted in increased energy expenditure compared with running on smooth terrain. Several biomechanical adjustments contributed to this increase in energetic cost.

Subjects did not exhibit changes in mean step parameters between the two conditions, but there were differences in step parameter variability. Joint angle, torque and power were mostly unaffected by the terrain and only the ankle joint showed a significant decrease in joint power.

In addition, we observed increased muscle activity in three proximal leg muscles vastus medialis, rectus femoris and medial hamstring , and increased muscle mutual contraction between the vastus medialis and medial hamstring muscles. Subjects also demonstrated higher leg stiffness when running on uneven terrain compared with smooth terrain.

Running and walking on the uneven terrain resulted in significant increases in energy expenditure when compared with running and walking on the even surface Fig. During running, energetic cost increased from 9. This percentage increase in running energy expenditure was much lower than the percentage increase found during walking on uneven terrain.

In contrast to running, metabolic energy expenditure during walking on uneven terrain increased from 2. This suggests that the biomechanical adaptations during walking in this study are likely the same as we have previously described, even though walking surfaces and subject footwear differed between the two studies. Although the percentage increases in energy expenditure were different between walking and running, the absolute increases in energetic cost were similar: 0.

The mean standing metabolic rate was 1. Net metabolic rate for walking and running on the even and uneven surfaces. All net metabolic rates are normalized to subject mass and show the absolute changes in energetics when walking and running on uneven terrain compared with smooth terrain.

Percentages indicate the increases in energetic cost caused by uneven terrain when compared with even walking or running. We saw no changes in mean step parameters width, length, height and period , although step variability increased for all parameters during running on uneven terrain compared with even terrain Table 1. Subjects showed few changes in joint kinematics and kinetics during running on uneven terrain compared with even terrain, with most notable changes occurring at the ankle joint.

During running on uneven terrain, joint angles in the sagittal plane showed slightly higher peak flexion angles in the knee and hip during mid-stance, possibly to allow for greater leg clearance Fig. Qualitative examination of the ankle angle showed a slightly decreased range of motion on uneven terrain compared with even terrain, although subjects appeared to maintain a similar heel-strike footfall pattern on the two surfaces.

This reduced range of ankle motion suggests that subjects ran with slightly flatter feet when on uneven ground. In contrast, the knee and hip joints showed little change. The timing of toe-off with respect to stride timing did not differ between the two running conditions. Joint angle, torque and power versus stride time for running on even and uneven terrain.

Plotted in solid lines are the mean trajectories for the ankle, knee and hip against percentage stride time for running during uneven and even terrain conditions. Shaded areas denote the mean s. Strides start and end at same-side heel-strike. Dashed vertical gray line indicates toe-off. Joint motion variability was also greater on uneven terrain compared with even terrain Fig.

Running on the uneven surface also affected the amount of positive and negative joint work done at the ankle Fig. Positive ankle work decreased by 0. Positive and negative joint work for the knee and hip were not statistically different between the two running conditions.

Ankle, knee and hip work per stride for the two running conditions. Values are shown for positive and negative work for the three joints, with error bars denoting s.

Subjects showed increases in muscle activity variability, mean muscle activity and muscle co-activation in the thigh muscles when running on uneven terrain compared with running on even ground Fig.

However, the vastus lateralis VL and all muscles in the lower leg showed no significant differences in mean muscle activity between conditions Fig. Averaged electromyographic EMG activity versus stride time for running on even and uneven terrain. All EMG profiles were normalized to the maximum mean muscle activity over the two running conditions, for each muscle and subject.

Strides start and end at same-side heel-strikes. Gray bars indicate statistically significant increases in mutual muscle contraction, with darker colors indicating larger percentage increases from the even to the uneven running condition. Mean rectified EMG activity values. Mean subject EMG profiles were first normalized to maximum mean muscle activity over the two running conditions, for each muscle and subject, and then averaged over stride time to produce subject average EMG activity values.

Bars indicate s. All but three muscles showed a significant increase in electromyographic EMG variability when running on the uneven terrain Fig.

Only two muscles in the lower leg and three muscles in the thigh showed increases in variability s. The muscle pair also demonstrated increased muscle co-activation during swing, although, because of minimal muscle activity of the two muscles during this time, these increases are likely inconsequential.

Vertical ground reaction forces, normalized to subject weight, remained largely unchanged for running on uneven terrain compared with even terrain Fig. The peak maximum force was not statistically different for the two running conditions. Vertical ground reaction forces, effective leg length and leg stiffness calculations for the two running conditions. A Mean vertical ground reaction forces normalized to subject weight solid lines , and effective leg lengths normalized to mean subject leg length thick dashed lines , versus stance duration for running on even and uneven terrain.

Shaded area denotes the mean s. B Normalized vertical ground reaction force plotted against the normalized effective leg length for the two running conditions. Mean leg stiffness values are presented for two leg stiffness calculation methods: k max equals the maximum force divided by the maximum leg length displacement and k fit is the slope of the linear fit to the leg stiffness curve.

Subjects ran in a slightly more crouched posture when on uneven terrain compared with running on the even surface Fig. Subjects contacted the ground at heel-strike with a more bent leg, and hence a shorter leg length 0. Similarly, leg length before toe-off decreased significantly from 1. In addition, the minimum leg length during mid-stance was longer on uneven terrain 0.

Primarily due to different leg length dynamics, subjects ran on stiffer legs when running on uneven terrain compared with running on even ground Fig. In this study we quantified the changes in energetics and biomechanics between running on uneven terrain and on flat, smooth terrain.

Our findings supported our hypotheses, primarily that running is more energetically costly on uneven terrain compared with even terrain. However, this increase was much smaller than the increase caused by the same surface during walking.

More specifically, we found a 0. Although the percentage changes were quite different between the two locomotion types, it is important to note that the absolute increases were very similar. These absolute energetic increases could be related to the total mechanical energy fluctuations caused by the uneven surface. For example, running uphill and downhill for an equal distance would result in greater energy expenditure than running on level ground for the same total distance Margaria, If we equate the uneven surface to a series of steps up and down an incline, it would be reasonable to expect an increase in energy expenditure as well.

If we consider the mean step length of our runners 0. However, the true energetic increase due to incline variations is likely much smaller. This suggests that factors other than changes in mechanical work contribute to energy expenditure on uneven terrain during running. As expected, we saw changes in step length and width variabilities across the two surfaces.

This is consistent with past research, which has shown that challenges to locomotor stability tend to produce more step variability during walking Thies et al.

Greater step variability during walking also seems related to active stabilizing adjustments for maintaining lateral balance Bauby and Kuo, ; Donelan et al.

In contrast, during running, humans tend to prefer narrow step widths close to the midline of the body Cavanagh, This is because narrow step widths result in reduced lateral moments about the center of mass and tend to reduce energetic cost compared with larger step widths. Based on previous research Arellano and Kram, , reducing step width and step width variability during running leads to a reduction in energy expenditure. This suggests that the energetic increase caused by changes in step parameters was negligible.

A significant finding of our study is that the absolute changes in energetic cost are independent of locomotor gait. The similar absolute changes for walking and running suggest that the dominant factor responsible for increases in metabolic cost during locomotion on uneven surfaces may be related to surface height variability and the corresponding vertical motion of the center of mass.

It would be interesting to examine a range of surface height variabilities and their effects on walking and running energetics. This could provide insight into whether walking and running have similar biomechanical mechanisms responsible for energetic cost differences. Another important finding of this study is that the lower limb joints that compensate for locomotion on uneven terrain are very different between walking and running. During walking, ankle joint dynamics remain invariable while the knee and hip joints compensate with greater positive work production Voloshina et al.

In contrast, running on uneven terrain only significantly affects work done at the ankle joint. The most likely explanation for this contrast in joint kinetic adaptations is the reliance on different biomechanical mechanisms for the two gaits. Running can be compared to a spring-mass system, with the lower limb functioning as if it were a single compression spring Farley and Ferris, ; McMahon and Cheng, In contrast, walking has inverted pendulum dynamics with differentiation by joint that is unlike running Alexander, ; Farley and Ferris, ; Kuo, ; McGeer, These differences in fundamental dynamics suggest that each gait has different benefits and drawbacks to joint-specific adaptations on uneven terrain.

The decrease in ankle work seen during running on uneven terrain compared with even ground is likely due to the high load sensitivity of the ankle joint. Muscles at the distal joints rely on high-gain proprioceptive feedback and are often the first to encounter perturbations due to uneven terrain Daley and Biewener,