Youdas, J, Krause, D, Harmsen, W, Laskowski, E; Mayo Clinic, Rochester, MN, USA. youdas.james@mayo.edu.

PURPOSE: The purpose of this study was to describe the change in hamstring muscle length (HML) in healthy people between the ages of 20 and 79 years. BACKGROUND: Physical therapists routinely assess HML during the patient examination. Presently, data is unavailable which describes the change in HML in healthy people over a timespan of six decades using procedures common to a physical therapy clinic. SUBJECTS: Assessments were performed on 209 volunteers, 99 men and 110 women, whose ages ranged from 20 to 79 years. Seventy-five percent of the subjects reported a physical exercise program of at least three times per week, whereas only 34 percent regularly stretched their hamstring muscles. METHODS: HML was assessed indirectly using three techniques: passive straight leg raise (PSLR), popliteal angle (PA), and the sit-and-reach test (SRT). PSLR and PA were measured with a universal goniometer, whereas the SRT was obtained with an inclinometer. Additionally, the standing lumbar lordosis (LL) was measured with a flexible curve molded to the contour of the lumbar spine. ANALYSIS: Intraclass correlation coefficients [ICC (1,1)] were used to express the reliability of the measurements of HML and LL. Descriptive statistics were calculated for measurements of HML and LL. The effect of age and gender on HML was assessed by a generalized linear model. Spearman correlation coefficients estimated the association between the three measures of HML and the association between LL and HML. RESULTS: The ICC for standing LL was .81, whereas the ICC value for each estimate of HML ranged from .97 to .98. Descriptive statistics for HML and LL were combined for men and women: PSLR (72° ± 10); PA (147° ± 12); SRT (87.1° ± 11.4); LL (45° ± 9). Men demonstrated less HML than women of the same age for each METHOD: PSLR = 8.5° ; PA = 11.3° ; and SRT = 12.5° . For PSLR and PA, men and women lost about 1° of HML per decade and 1.7° per decade for the SRT. Spearman correlation coefficients for the three measurements of HML ranged from .59 to .78 (PSLR v.s. PA, .78; PSLR v.s. SRT, .59; PA v.s. SRT, .66). Spearman correlation coefficients for the relationship between LL and HML ranged from .06 to .16 (LL v.s. PSLR, .06; LL v.s. PA, .14; LL v.s. SRT, .16). CONCLUSIONS: Measurements of HML and LL were reliable. For a given age and measurement technique, women demonstrated greater HML than men. Furthermore, there is no relationship between HML and standing LL. FUNDING SOURCE: Mayo Clinic.

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