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Background and aim: Grip strength (GS) is an important measure of general health to predict mortality, disability and function of the hand. The purpose of this study was to develop equations to predict grip strength based on several anthropometric measurements using a multiple regression analysis.
Materials and Methods: Four hundred and eleven males and 671 females college students, ages 18-30 years, in good health, participated voluntarily in this study. This sample was randomly assigned to the model-development (n=867) and cross-validation (n=215) groups. Four equations were developed by using data from the model development group, then cross-validated on the second group. A hand-held dynamometer was used to measure grip strengths. All anthropometric measurements such as hand anthropometry, forearm circumference (FC), lean body mass, skeletal muscle mass and arm muscle area were taken according to standard techniques.
Results: It was found that grip strength has a significant correlation with all anthropometric measurements. Forearm length (FL) was correlated to grip (68% explained variance) in a linear relationship, followed by upper limb length and SM. All four equations were confirmed by cross-validation. Because of simplicity and easy-to-measure the following equations were selected for prediction grip: Dominant hand, A) 0.464×Age(yr)+0.392×Height(cm)+0.681×BMI-13.035×Sex(0 for men and 1 for women)-46.160, B) 0.029×FC×FL-8.634×sex+13.872 Non-dominant hand: C) 0.347×Age+0.386× Height+0.657×BMI-13.313×Sex-44.243, D) 0.029×FC×FL-8.752×sex+13.788.
Conclusion: The six easy-to-measure cofactors sex, age, height, BMI, forearm length and forearm circumference provide a highly accurate prediction of normative grip strength.

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Background and Aim: In studies of the spinal circuits, change of Renshaw cell activity is measured by H´ response. For recording H' response, new electrical stimulation device was designed and built and the first recorded H' response in Iran was done. The purpose of this study was to investigate the intersession and intra-session reliability of peak amplitude of H´ response and its related intensity detected of new device.
Materials and Methods: Soleus muscles of dominant extremity in 6 subjects were tested in 3 sessions and 2 times in each session that intra-session interval was 20 minutes and intersession interval was 1 week.
Results: Peak amplitude and its related intensity exhibited intra-session and intersession reliability 0.92, 0.98, 0.86 and 0.9 respectively. Standard Error of Measurement was 0.37 and 0.47 for intrasession and 0.44 and 1.06 for inter session respectively.
Conclusion: Peak amplitude and its related intensity exhibited very high intra-session and intersession reliability.