Abstract
Low reproducibility and non-optimal sample sizes are current concerns in scientific research, especially within human movement studies. Therefore, this study aimed to examine the implications of different sample sizes and number of steps on data variability and statistical outcomes from kinematic and kinetics running biomechanical variables. Forty-four participants ran overground using their preferred technique (normal) and minimizing the contact sound volume (silent). Running speed, peak vertical, braking forces, and vertical average loading rate were extracted from > 40 steps/runner. Data stability was computed using a sequential estimation technique. Statistical outcomes (p values and effect sizes) from the comparison normal vs silent running were extracted from 100,000 random samples, using various combinations of sample size (from 10 to 40 runners) and number of steps (from 5 to 40 steps). The results showed that only 35% of the study sample could reach average stability using up to 10 steps across all biomechanical variables. The loading rate was consistently significantly lower during silent running compared to normal running, with large effect sizes across all combinations. However, variables presenting small or medium effect sizes (running speed and peak braking force), required > 20 runners to reach significant differences. Therefore, varying sample sizes and number of steps are shown to influence the normal vs silent running statistical outcomes in a variable-dependent manner. Based on our results, we recommend that studies involving analysis of traditional running biomechanical variables use a minimum of 25 participants and 25 steps from each participant to provide appropriate data stability and statistical power.
Highlights
Low reproducibility and non-optimal sample sizes are current concerns in scientific research, especially within human movement studies
There were significant reductions in loading rate (p < 0.0001, effect size: 1.41, Fig. 2), peak braking force (p < 0.0001, effect size: 0.66), running speed (p < 0.05, effect size: 0.167) and foot contact angle (p < 0.0001, effect size: 1.03) during silent running when compared to normal running
The main findings of our study were that: (1) stable averages across the investigated biomechanical variables require more than 10 steps for the majority of runners, as less than 35% of runners reached a stable average within 10 steps or less
Summary
Low reproducibility and non-optimal sample sizes are current concerns in scientific research, especially within human movement studies. This study aimed to examine the implications of different sample sizes and number of steps on data variability and statistical outcomes from kinematic and kinetics running biomechanical variables. There are two types of parameters: global parameters, defined as the output of the human system as an entity (i.e., speed, contact time, step length, center of mass); and localized parameters, defined as output related to movement performance (i.e., joint angles, moments, power, ground reaction force)[1]. The CV from the vertical loading rate ranges from 1218 to 109%17, whereas the CV from foot angle at initial contact ranges from 2 419 up to 3288%17 These statistics suggest that different variables in running biomechanics present specific variability patterns. Defining the number of steps and/or sample size for a running experiment based on only one variable may affect the results of all other recorded variables
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
