Background

Aberrant biomechanics may influence osteoarthritis-associated physical activity limitations. Our purpose was to evaluate the association of walking energetics, fatigue, and fatigability on physical activity in people with knee osteoarthritis. We hypothesized that using increased energy for walking, experiencing more fatigue, or being more fatigable are associated with less activity, and that fatigue and fatigability mediate the relationships between walking energetics and physical activity.

Methods

We tested our hypothesis in 30 people with knee osteoarthritis (age 58 ± 9 years, 10 Male/20 Female). Physical activity was assessed using the University of California Los Angeles score. We used a six-minute walk test to predict VO₂max. Next we used a portable oxygen exchange system to measure relative energy used (100 * VO₂rate/VO₂max) and VO₂cost during walking at preferred speeds. We used the Knee injury and Osteoarthritis Outcome Score subscale to quantify pain, and the Patient Reported Outcome Measurement Instrument System Fatigue survey and a treadmill-based fatigability test to assess fatigue and fatigability. Spearman correlations, regression, and mediation analysis were used to test our hypotheses.

Findings

Greater energy used during walking, fatigue, and fatigability were all associated with lower physical activity (rho = −0.585 to −0.379, P = 0.001 to 0.043). These associations persisted when incorporating pain into the models. Fatigue and fatigability mediated the associations between walking energetics and physical activity.

Interpretation

Walking energetics could be a useful target to promote physical activity in people with osteoarthritis. Further, the effect of walking energetics on physical activity may work through its impact on fatigability.

中文翻译：

---

步行能量和疲劳与膝骨关节炎患者的身体活动有关

背景

异常的生物力学可能会影响骨关节炎相关的身体活动限制。我们的目的是评估步行能量、疲劳和易疲劳性与膝骨关节炎患者身体活动的关联。我们假设步行时使用更多的能量、经历更多的疲劳或更易疲劳与较少的活动相关，并且疲劳和易疲劳性调节步行能量和身体活动之间的关系。

方法

我们在 30 名膝骨关节炎患者（年龄 58 ± 9 岁，10 名男性/20 名女性）中测试了我们的假设。使用加州大学洛杉矶分校评分评估身体活动。我们使用六分钟步行测试来预测 VO ₂最大值。接下来，我们使用便携式氧气交换系统来测量以首选速度行走期间使用的相对能量（100 * VO ₂速率/VO ₂最大值）和 VO _2成本。我们使用膝关节损伤和骨关节炎结果评分子量表来量化疼痛，并使用患者报告的结果测量仪器系统疲劳调查和基于跑步机的易疲劳性测试来评估疲劳和易疲劳性。Spearman 相关性、回归和中介分析用于检验我们的假设。

发现

行走时消耗更多能量、疲劳和易疲劳都与较低的体力活动有关（rho = −0.585 至 −0.379，P  = 0.001 至 0.043）。当将疼痛纳入模型时，这些关联仍然存在。疲劳和易疲劳性介导了步行能量学和身体活动之间的关联。

解释

步行能量学可能是促进骨关节炎患者身体活动的有用目标。此外，步行能量学对体力活动的影响可能通过其对易疲劳性的影响来发挥作用。