The purpose of this study was to determine the muscle activities of the erector spinae (ES), gluteus maximus (Gmax), gluteus medius (Gmed), and the hamstring (HAM) and the ratios of Gmax/ES, Gmax/HAM, and Gmed/HAM during the prone heel squeeze (PHS) with different knee flexion angles (45˚, 90˚, and 135˚). Fifteen young and healthy subjects (8 men, 7 women) were recruited for the study. Surface electromyography signals were collected on ES, Gmax, Gmed, and HAM during PHS. A separate one-way analysis of variance with repeated measures was used to determine the significance of the muscle activities of ES, Gmax, Gmed, and HAM and the ratios of Gmax/ES, Gmax/HAM, and Gmed/HAM with different knee flexion angles during PHS. There was a significant increase in the Gmax activity at the knee flexion of 90˚ in comparison with that of the 45˚ (p=.016). There were significant increases in the Gmed activity at the knee flexion of 90˚ (p=.008) and 135˚ (p=.006) in comparison with that of the 45˚. There were significant decreases in the HAM activity at the knee flexion of 90˚ (p=.009) and 135˚ (p=.004) in comparison with that of the 45˚. There were significant increases in the Gmax/HAM muscle activity ratio at the knee flexion of 90˚ (p=.007) and 135˚ (p=.012) in comparison with that of the 45˚. There were significant increase in the Gmed/HAM muscle activity ratio at the knee flexion of 135˚ in comparison with that of the 45˚ (p=.008). The knee flexion of 90˚ during PHS can induce decreasing activity of HAM and increasing activity of Gmax, and the knee flexion of 135˚ during PHS can induce decreasing activity of HAM and increasing activity of Gmed. Hence, PHS with different knee flexion positions could be considered for the different target muscle.

The purposes of the current study were to (1) estimate the inter-rater agreement for visual assessment of scapular downward rotation (SDR), (2) develop the scapular downward rotation index (SDRI) as a method to measure SDR objectively and quantitatively, and (3) analyze the intra- and inter-rater reliability of the SDRI. Twenty subjects with scapular downward rotation syndrome (SDRS) were recruited for this study. The visual assessment and the measurement for the SDRI were conducted by two examiners in two sessions each. The SDRI [(a-b)÷a×100] is calculated with the measurement of two linear distances: One is a perpendicular distance from the root of the scapular spine to the thoracic mid-line (a), and the other is a perpendicular distance from the inferior angle of the scapula to the thoracic mid-line (b). Cohen’s kappa coefficient was calculated to estimate the inter-rater agreement for visual assessment. Intra-class correlation coefficients (ICCs) with a 95% confidence interval (CI), the standard error of measurement, and minimal detectable differences were calculated to assess intra- and inter-rater reliability of SDR measurement using the SDRI. The results indicated that the kappa coefficient of inter-rater agreement for visual assessment was fair (κ=.21). The intra-rater reliability of SDR measurement using the SDRI was excellent for examiner 1 (ICC=.92, 95% CI=.78∼.97) and good for examiner 2 (ICC=.82, 95% CI=.55∼.93). The inter-rater reliability was moderate (ICC=.73, 95% CI=.32∼.89). These findings showed that SDR measurement using the SDRI for subjects with SDRS may be considered reliable and better than the visual assessment.