The Effects Of Alteration In Stride Frequency During Bouts Of Downhill Running: An Emg, Kinematic, And Metabolic Analysis

Open Access
Author:
Lutz, Ryan William
Area of Honors:
Kinesiology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Jinger S. Gottschall, Thesis Supervisor
  • Jinger S. Gottschall, Honors Advisor
  • Stephen Jacob Piazza, Faculty Reader
Keywords:
  • Stride Frequency
  • Downhill Running
  • EMG Kinematic Metabolic Downhill Running.
Abstract:
Previous literature regarding running has largely been about the benefits associated with level and uphill running. For this reason, I thought it would be interesting to study the effects downhill running has on the human body. Specifically, when running downhill what type of stride frequency will produce the most optimal results, depending on the runner. The effects of altered stride frequency can have profound implications for those trying to either lose weight or beat a previous time. Stride frequency was altered in one of two ways, by either increasing the frequency to 15% above the participants preferred frequency, or by decreasing the frequency by 15%. The specific parameters used to gauge which running style was most efficient, metabolic, kinematic, as well as EMG data was collected. 10 healthy college students were recruited for the study and asked to run on a treadmill at 3 m/s for trials lasting 2 minutes each. During this time information regarding muscle activity was collected for eight muscles of the lower limbs which included: TA, LG, SL, VM, VL, RF, BF, and ST. Temporal-spatial variables as well as oxygen consumption (kg/ml/min) were also measured while changing the stride frequency. Due to the lack of extensive research regarding downhill running, I formulated my hypothesis on previous articles related to downhill walking or level running. Based on these articles I expected to see a decrease in muscle activity when running downhill as compared to level running. I also predicted that the muscles would be least activated when running downhill with strides 15% faster than the preferred frequency. Due to the direct relationship between muscle behavior and metabolic activity I also expected the least amount of oxygen consumption when running with strides 15% faster than preferred. In terms of kinematic variables, I expected to see an increase in stride time and stance time when running with strides 15% slower than preferred. Overall, the results matched my hypothesis and the results of previous studies related to the experiment. We found that metabolically, running with the participants preferred stride frequency proved most efficient, and provided support for many research articles claiming the human body will find the most efficient way to run given new circumstances. Perplexingly, the least amount of muscle activity was seen when participants ran with strides 15% faster than preferred. Due to these differences in efficiency, it is tough to conclude which running style should be utilized when running downhill but presents a unique opportunity for future research.