Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia, South Carolina, United States of America.
Department of Physical Therapy and Rehabilitation Sciences, Drexel University, Philadelphia, Pennsylvania, United States of America.
PLoS One. 2024 May 22;19(5):e0301872. doi: 10.1371/journal.pone.0301872. eCollection 2024.
The current clinical gold standard for assessing isometric quadriceps muscle strength is an isokinetic dynamometer (IKD). However, in clinics without an IKD, clinicians default to using handheld dynamometers (HHD), which are less reliable and accurate than the IKD, particularly for large muscle groups. A novel device (ND) was developed that locks the weight stack of weight machines, and measures forces applied to the machine, turning this equipment into an isometric dynamometer. The objectives of this study were to characterize the test-retest reliability of the ND, determine the within-day and between-days inter-rater reliability and concurrent validity compared with that of the HHD, in healthy volunteers (HV) and individuals with knee osteoarthritis (OA) for measuring knee extensors isometric muscle force.
29 healthy (age = 28.4 ± 7.4 years) and 15 knee OA (age = 37.6 ± 13.4 years) participants completed three maximum force isometric strength testing trials on dominant side knee extensor muscles on three devices (ND, HHD, and IKD) in two separate sessions by two raters. The maximum force (Fmax) produced, and the force-time series were recorded. Reliability and validity were assessed using Intraclass Correlation Coefficient (ICC), Bland-Altman Plots, Pearson's r, and cross-correlations.
The ND demonstrated excellent test-retest reliability (ICC2,3 = 0.97). The within-day (ICC2,3 = 0.88) and between-day inter-rater reliability (ICC2,3 = 0.87) was good for HHD. The ND showed excellent within-day (ICC2,3 = 0.93) and good between-day (ICC2,3 = 0.89) inter-rater reliability. The Bland-Altman analysis revealed HHD systematic bias and underestimation of force particularly with quadriceps force values exceeding 450 N. Mean differences were found in maximum force between HHD vs. IKD (MDabs = 58 N, p < .001) but not the HHD vs. ND (MDabs = 24 N, p = .267) or ND vs. IKD (MDabs = 34 N, p = .051). The concurrent validity of Fmax (r = 0.81) and force-time curve correlation (0.96 ± 0.05) were the highest between the ND and IKD.
The ND's test-retest reliability and concurrent validity make it a potential strength assessment tool with utility in physical therapy and fitness settings for large muscle groups such as the knee extensors.
目前评估等长股四头肌力量的临床金标准是等速测力计（IKD）。然而，在没有 IKD 的临床科室，临床医生默认使用手持测力计（HHD），其可靠性和准确性不及 IKD，尤其是对于大肌群。开发了一种新型设备（ND），它可以锁定举重机的重量托盘，并测量施加在机器上的力，从而将该设备转变为等动测力计。本研究的目的是描述 ND 的测试-再测试可靠性，确定其在健康志愿者（HV）和膝骨关节炎（OA）个体中与 HHD 相比的日内和日间间测者间可靠性以及与 HHD 的同时效度，用于测量膝关节伸肌的等长肌肉力量。
29 名健康志愿者（年龄=28.4±7.4 岁）和 15 名膝骨关节炎患者（年龄=37.6±13.4 岁）在两次单独的会议中，由两名测者使用三种设备（ND、HHD 和 IKD）在其优势侧膝关节伸肌上完成三次最大力等长强度测试。记录最大力（Fmax）和力时间序列。使用组内相关系数（ICC）、Bland-Altman 图、Pearson r 和互相关来评估可靠性和有效性。
ND 表现出极好的测试-再测试可靠性（ICC2,3=0.97）。HHD 的日内（ICC2,3=0.88）和日间间测者间可靠性（ICC2,3=0.87）良好。ND 表现出极好的日内（ICC2,3=0.93）和良好的日间间测者间可靠性（ICC2,3=0.89）。Bland-Altman 分析显示 HHD 存在系统偏差，并且低估了力，尤其是在股四头肌力值超过 450N 时。HHD 与 IKD 之间的最大力存在均值差异（MDabs=58N，p<0.001），但 HHD 与 ND（MDabs=24N，p=0.267）或 ND 与 IKD（MDabs=34N，p=0.051）之间没有均值差异。ND 与 IKD 之间的 Fmax（r=0.81）和力-时间曲线相关性（0.96±0.05）的同时效度最高。
ND 的测试-再测试可靠性和同时效度使其成为一种潜在的力量评估工具，在物理治疗和健身环境中对大肌群（如膝关节伸肌）具有实用性。
