Skipping the Injuries: A Biomechanical and Metabolic Comparison Between Skipping & Running
Introduction: Benefits of aerobic exercise are apparent; the rising awareness has caused an increase in running participation and, an undeniable trend toward injury. The inherit injury risk associated with running calls for an alternate way to simultaneously achieve the benefits of aerobic exercise, while minimizing stress imparted on the body. Skipping presents an alternative movement pattern unique in its initiation and composition. Skipping is a voluntary decision, as opposed to a scaling progressing seen in the transition from walking to running and incorporates a double support, flight, and single limb support phase. We propose skipping to be an advantageous form of aerobic exercise, allowing a person to achieve increased training benefits with diminished risk of injury and subsequent reduction in training. Objective: This study has three related purposes aimed at describing, for the first time, how one skips. The first purpose compared basic gait characteristics; lower extremity kinematics and kinetics including ground reaction forces, joint torques, and powers in skipping and running. The second purpose investigated knee loads in skipping by comparing tibiofemoral and patellofemoral joint forces in skipping and running. The final purpose compared the metabolic cost of skipping to that of running. Methods: Twenty recreation active individuals mean age 21.5 ([plus-or-minus]2) were recruited to complete a three day training program intended to familiarize participants with the skipping movement and testing environment. Training program consisted of cumulative 3 miles of skipping on three separate, not necessarily consecutive, days. Data collection employed a metabolic cart and treadmill to capture oxygen consumption in skipping and running. This was followed by randomized overground motion capture of the three conditions: skipping first leg (skip1) second leg (skip2) and running step (run). Speed was consistent 2.68 m/s across metabolic and biomechanical collections. Variables of interests were averaged across trials for each participant and mass normalized when applicable. One way ANOVA with repeated measures analyzed the biomechanical scores per variable per condition. Metabolic cost was compared with a dependent t- test between skipping and running. Scheffe post hoc test determined significant, alpha set to 0.05. Results: Not only are skipping and running significantly different from one another in kinetics, kinematics, and metabolic parameters, the two steps of skipping differed significantly. Running displayed greater vertical ground reaction force peaks, larger maximal knee extensor torque values, higher peak negative power and work and greater peak maximal positive power at the knee, with average increase of 23% in knee compressive force as compared to skipping. Conversely, skipping had greater cadence, peak horizontal ground reaction force, maximum hip and ankle extensor torque, peak negative power and work, positive power at the ankle, a 27% greater metabolic cost and 36% greater caloric consumption. Between the two skipping steps skip2 had the highest cadence, peak horizontal ground reaction force, maximum ankle extensor torque, peak negative power, work, and positive power. Each of the two skip steps have a separate function; skip1 had predominately eccentric muscle functioned and acted to slow the body down, while skip2 has a concentric bias in muscle activity and propelled the body forward into the next step. Evidence of this segregation can be seen in the distribution of the braking and propelling impulses. Conclusions: Skipping and running present as significantly different movement methods. The decreased stride length associated with the skipping stride was correlated with the smaller knee compressive forces. The increased oxygen consumption needed to skip was in part explained by the nearly double vertical displacement of the center of mass. Further, the two alternating skipping steps that complete a stride made it unique from the one cyclical running step repeated in constant successive intervals. Skipping was temporally and spatially asymmetrical with successive foot falls partitioned into dominant functions, either braking or propelling the body. Thus, the energy saving methods proposed to be employed by tendons as they stretch and recoil may not be employed, creating a diminished energy return.
McDonnell, Jessica. (May 2016). Skipping the Injuries: A Biomechanical and Metabolic Comparison Between Skipping & Running (Master's Thesis, East Carolina University). Retrieved from the Scholarship. (http://hdl.handle.net/10342/5919.)
McDonnell, Jessica. Skipping the Injuries: A Biomechanical and Metabolic Comparison Between Skipping & Running. Master's Thesis. East Carolina University, May 2016. The Scholarship. http://hdl.handle.net/10342/5919. August 16, 2018.
McDonnell, Jessica, “Skipping the Injuries: A Biomechanical and Metabolic Comparison Between Skipping & Running” (Master's Thesis., East Carolina University, May 2016).
McDonnell, Jessica. Skipping the Injuries: A Biomechanical and Metabolic Comparison Between Skipping & Running [Master's Thesis]. Greenville, NC: East Carolina University; May 2016.
East Carolina University