Ground Reaction Force And Electromyograms Of Lower Limb Muscles During Fast Walking

Abstract

Endurance exercise has been known to be a potent procedure to avoid obesity and its related cardiovascular diseases and to improve glycemic control. Several types of exercise modalities (e.g., walking, running, swimming) are currently utilized, but walking would be most prevalent and accessible. Although general walking is performed around 4-5 km/h, walking at faster speed (fast walking) has been increasing much attention. In previous studies, five months of fast walking increased maximal oxygen uptake and lowered blood pressure (Nemoto et al., 2007). However, the impact of fast walking on mechanical variables as well as muscle activity has not been fully clarified. PURPOSE: To compare ground reaction force and muscle activity between fast walking and running at the equivalent speed. METHODS: Eight males (age; 21 ± 1 yr, height; 172.1 ± 1.7 cm, bodyweight; 62.1 ± 7.0 kg,) participated in the present study. All subjects performed four minutes of slow walking (at 45% of the maximum walking speed, SW), fast walking (at 85% of the maximum walking speed, FW) and running at the equivalent speed from fast walking (Run). During each condition, ground reaction force (GRF) and electromyography (EMG) of seven muscles (gluteus maximus, biceps femoris, rectus femoris, vastus lateralis, gastrocnemius medialis, soleus, and tibialis anterior) were evaluated. We analyzed GRF, average muscle activity (aEMG) and integrated volume (iEMG) during contact phase. RESULTS: In the vertical component of GRF, the load of impact (the maximal and the average values) in FW was lower than those of Run (maximal; 150 ± 25 %BW vs. 219 ± 33 %BW, average; 89 ± 12 %BW vs. 119 ± 19 %BW, p < 0.05). In soleus, aEMG during the ground contact phase in FW (25 ± 9 %MVC) was greater than in SW (13 ± 4 %MVC, p < 0.05). However, no difference was found between FW and Run, but iEMG presented higher value in FW (13 ± 5 %MVC vs. 9 ± 4 %MVC, p < 0.05). In tibialis anterior, aEMG was higher in FW (12 ± 6 %MVC) than in SW (6 ± 4 %MVC) and Run (6 ± 3 %MVC, p < 0.05). iEMG was higher in FW (6 ± 3 %MVC) than in Run (2 ± 1 %MVC, p < 0.05), with no difference between the SW and FW. CONCLUSIONS: The ground reaction force during fast walking was lower than running at the same speed, but the muscle activities of lower limb muscles were comparable.