Comparison Of Biomechanics And Metabolic Cost Among Elliptical Exercises And Running In Runners

Abstract

Standard elliptical devices are a popular cross-training modality as they have similar metabolic cost as running with minimal lower extremity impact. A modified elliptical device produces lateral movement of the lower extremities and yields knee and hip joint motion that may have positive clinical implications for injured runners. PURPOSE: Compare acute differences in joint kinematics and metabolic cost between treadmill running (TR), standard elliptical (SE), and lateral elliptical (LE) in runners. METHODS: 16 non-injured runners (8 men) completed ten minutes of randomized exercise on TR, SE and LE on separate days. 3D knee and hip joint kinematics for the right limb were collected using a motion capture system (Qualisys). Oxygen consumption (VO2; ml/kg/min) was collected using a metabolic system (Parvo Medics). Motion data were analyzed using Visual3D (C-Motion). One-way repeated measures ANOVA to assess exercise type main effects (p<0.05) and cohen’s d effect sizes (ES) to assess mean differences were used. RESULTS: The knee ROM were different in LE (69.2±9.4°; extension) compared to SE (32.4±6.5°; ES=4.70; extension) and TR (-17.9±3.2°; ES=12.81; flexion) and, different between SE and TR (ES=10.14). The transverse plane hip ROM were different in LE (-8.9±8.1°; ES=2.94; external rotation) and TR (-3.3±4.9°; ES=3.07; external rotation) compared to SE (8.0±2.2°; internal rotation) and different between LE and SE (ES=0.86). Frontal plane hip ROM were different in LE (-16.4±5.5°; ES=5.32; abduction) and SE (2.7±1.9°; ES=1.27; adduction) compared to TR (5.3±2.3°; adduction) and, different between LE and SE (ES=4.79). Contralateral pelvic drop ROM were greater in LE (-5.3±4.8°; ES=0.83) and TR (-5.7±1.9°; ES=1.71) compared to SE (-2.3±2.2°). Finally, VO2 were greater in both TR (36.9±4.4; ES=2.65) and LE (36.8±8.3; ES=1.70) compared to SE (26.1±4.0). CONCLUSIONS: The LE yields joint motions that could have strengthening effects to help prevent knee and hip joint running injuries. However, greater pelvis drop in LE may have injurious consequences. The greater VO2 during LE suggests that LE may be more comparable to TR for metabolic activity than SE. The greater VO2 in LE may be due to greater frontal plane muscle control. Studies on chronic elliptical training effects are warranted in healthy and injured runners.