Can Tai Chi training impact fractal stride time dynamics, an index of gait health, in older adults? Cross-sectional and randomized trial studies

PurposeTo determine if Tai Chi (TC) has an impact on long-range correlations and fractal-like scaling in gait stride time dynamics, previously shown to be associated with aging, neurodegenerative disease, and fall risk.MethodsUsing Detrended Fluctuation Analysis (DFA), this study evaluated the impact of TC mind-body exercise training on stride time dynamics assessed during 10 minute bouts of overground walking. A hybrid study design investigated long-term effects of TC via a cross-sectional comparison of 27 TC experts (24.5 ± 11.8 yrs experience) and 60 age- and gender matched TC-naïve older adults (50–70 yrs). Shorter-term effects of TC were assessed by randomly allocating TC-naïve participants to either 6 months of TC training or to a waitlist control. The alpha (α) long-range scaling coefficient derived from DFA and gait speed were evaluated as outcomes.ResultsCross-sectional comparisons using confounder adjusted linear models suggest that TC experts exhibited significantly greater long-range scaling of gait stride time dynamics compared with TC-naïve adults. Longitudinal random-slopes with shared baseline models accounting for multiple confounders suggest that the effects of shorter-term TC training on gait dynamics were not statistically significant, but trended in the same direction as longer-term effects although effect sizes were very small. In contrast, gait speed was unaffected in both cross-sectional and longitudinal comparisons.ConclusionThese preliminary findings suggest that fractal-like measures of gait health may be sufficiently precise to capture the positive effects of exercise in the form of Tai Chi, thus warranting further investigation. These results motivate larger and longer-duration trials, in both healthy and health-challenged populations, to further evaluate the potential of Tai Chi to restore age-related declines in gait dynamics.Trial registrationThe randomized trial component of this study was registered at ClinicalTrials.gov (NCT01340365).研究目的：本研究旨在探究太极拳（Tai Chi, TC）对步态步间时间动力学中的长程相关性与类分形缩放特性的影响——此前已有研究证实，此类动力学特性与衰老、神经退行性疾病及跌倒风险密切相关。 研究方法：本研究采用去趋势波动分析（Detrended Fluctuation Analysis, DFA），评估太极拳身心锻炼训练对受试者在10分钟平地行走过程中测得的步间时间动力学特性的影响。本研究采用混合研究设计：一方面通过横断面比较，纳入27名太极拳练习专家（平均练习时长24.5±11.8年）与60名年龄、性别匹配的太极拳初练老年受试者（50~70岁），探究太极拳的长期效应；另一方面通过随机对照试验，将太极拳初练受试者随机分配至6个月太极拳训练组或等待列表对照组，评估太极拳的短期效应。本研究以DFA推导得到的α长程缩放系数与步态速度作为结局指标。 研究结果：经混杂因素校正的线性模型横断面比较结果显示，与太极拳初练受试者相比，太极拳练习专家的步态步间时间动力学长程缩放特性显著更强。纳入多混杂因素的共享基线纵向随机斜率模型分析结果显示，短期太极拳训练对步态动力学的影响未达到统计学显著性，但效应方向与长期效应一致，尽管效应量极小。与之形成对比的是，横断面与纵向分析均显示步态速度未受太极拳训练的影响。 研究结论：本初步研究结果表明，步态健康的类分形测量指标具有足够精度，可捕捉太极拳锻炼带来的积极效应，因此有必要开展进一步研究。本研究结果提示，需在健康人群与健康受损人群中开展规模更大、周期更长的试验，以进一步评估太极拳改善衰老相关步态动力学衰退的潜在潜力。 试验注册：本研究的随机对照试验部分已在ClinicalTrials.gov注册（注册号：NCT01340365）。