Available at: https://digitalcommons.calpoly.edu/theses/3057
Date of Award
6-2025
Degree Name
MS in Engineering - Biochemical Engineering
Department/Program
Biomedical Engineering
College
College of Engineering
Advisor
Scott Hazelwood
Advisor Department
Biomedical Engineering
Advisor College
College of Engineering
Abstract
With recent increases in participation in outdoor running events, there is a need for research in downhill gait biomechanics. One change that could impact joint loading is foot strike pattern. Foot strike patterns have been categorized into rearfoot-strike (RFS), midfoot-strike (MFS), and forefoot-strike (FFS) [1]. While 75-99% of distance runners naturally RFS on level surfaces, they tend to move towards FFS when it is necessary to reduce vertical loading conditions at the knee [1]. The purpose of this study was to examine differences in peak vertical knee and ankle forces, knee moment, and ankle power, as well as cumulative force per step in the knee and ankle, to determine if there is an optimal foot strike pattern to reduce injury risk in downhill running.
Ten male participants aged 18-23 were included in the study. An 11.45 degree wooden ramp was built and placed on a force plate with a calibrated motion capture system. Natural foot strike position (between FFS and RFS) was determined through observation of natural gait patterns. A 19 marker set was placed on participants, who then walked down the ramp, taking one or two leadup steps as their natural gait allowed, before their dominant leg struck the force plate, first with their natural foot strike position. After two successful trials, participants underwent a familiarization period, walking with their non-natural foot strike position. They were considered familiarized when they could take 20 consecutive steps on flat ground with the non-natural position, and walked down the ramp as many times as necessary until they consistently accurately struck with their non-natural pattern. Two more successful trials were taken. Data were processed and kinetics calculated, with paired t-tests performed for six variables: peak vertical knee and ankle force, peak knee moment, peak ankle power, and knee and ankle cumulative force (p< 0.05 significant).
FFS produced a higher vertical peak force in the knee (p =0.0045) and a higher ankle cumulative force (p =0.0252) on the downhill ramp. RFS produced a higher knee moment (p = 0.0268). Ankle peak vertical force (p =0.0837,), ankle power (p =0.0887), and knee cumulative force (p =0.0597) did not produce statistically significant differences.
The results of this study suggest that while RFS may have some benefit for injury risk, especially in the ankle, there are areas of strength in both RFS and FFS for preventing different types of injuries in the knee. Future study directions could include performing similar tests with running participants, looking into contact time as a potential factor in these relevant kinetics, and performing more tests to determine which loading pattern is more predictive of injuries between peak and cumulative loads.