Mechanical Stress Reduction Effect Smooth Walking That Is Gentle On Joints (New Ninja Walk)

Abstract

PURPOSE: Walking is a major exercise for maintaining good health. However, with age joint degeneration progresses and musculoskeletal tolerance to mechanical stress caused by walking decreases. Therefore, to extend the walking life without age-related walking problems, we developed New Ninja-Walk, which was designed in consideration of reducing mechanical stress, and then, examined the effects of its smooth walking. METHODS: The first examination, we measured 10-m walking speed and 3D acceleration using Safety Walk Navi (Descente Ltd, Osaka, Japan) for older adults (n = 451, 72.1 ± 5.1 years) who could walk on their own, and examined their acceleration distribution ranges, i.e. markers of mechanical stress during a walking test. In the second examination, a 30-minute New Ninja-Walk workshop was held for older adults (n = 67) who could walk on their own. Before and after the workshop, the same measurements and stride as the first examination were measured. Since the acceleration changes depending on the walking speed, only the participants whose speed change before and after was 0.2 m/sec or less (n = 47, 75.2 ± 6.1 years) were compared. RESULTS: In the first examination, there was a positive correlation between walking speed and acceleration (forward acceleration: r = 0.61, upward acceleration: r = 0.76, downward acceleration: 0.36, and lateral acceleration: r = 0.43, all P < 0.01). In addition, even if, their accelerations were same at the walking speed, a considerable width distribution area was observed. In the second examination, after introducing the New Ninja-Walk, their, stride narrowed from 0.433 ± 0.043 (height ratio) before the workshop to 0.417 ± 0.038 after the workshop (P < 0.01). Acceleration was reduced in three directions except downward (forward: to 0.668 ± 0.219 g from 0.789 ± 0.28 g, upward: to 0.418 ± 0.1 g from 0.4620.116 g, lateral: to 0.817 ± 0.216 from 0.936 ± 0.232 g, all P < 0.01). CONCLUSION: We found that the faster the walking speed, the greater the mechanical stress. However, there was a difference in mechanical stress depending on how they walked. As a result of devising and practicing a smooth walking style like a ninja, mechanical stress was generally reduced.