Sue K1, Momose K2, Karasawa S3, Katai S1, Kijima M4
1JA Nagano Kouseiren Kakeyu-Misayama Rehabilitation Center Kakeyu Hospital, Department of Rehabilitation, Ueda, Japan, 2Shinshu Univeristy School of Health Sciences, Department of Physical Therapy, Matsumoto, Japan, 3Fujimori Hospital, Department of Rehabilitation, Matsumoto, Japan, 4JA Nagano Kouseiren Kakeyu-Misayama Rehabilitation Center Kakeyu Hospital, Department of Radiology, Ueda, Japan
Background: Measuring isotonic muscle strength from 1 repetition maximum (1RM) is an important step in prescribing resistance training. However, measuring 1RM directly is time-consuming and may be unsafe for people at risk of injury or those with cardiovascular problems. Since skeletal muscle mass (SMM) has been demonstrated to have a strong relationship with muscle strength, measuring SMM can be considered as a viable option for the assessment of muscle strength. Recently, Bioelectrical Impedance Analysis (BIA) has been widely used for assessing SMM in clinical or research settings. Previous studies have demonstrated that the measurements obtained from BIA and isometric muscle strength were strongly correlated. But it is not clear whether there is relationship between measurements obtained from BIA and isotonic muscle strength, e.g. 1RM.
Purpose: The purpose of this study was to examine the relationship between measurements by BIA and 1RM, and also to examine the regression model for estimating 1RM from BIA measurements.
Methods: Study design: Observational cross sectional study. Subjects：A total of 30 healthy young Japanese subjects aged 28.3±4.0 years old (15 males, 15 females) participated in this study. The subjects were excluded from this study if they had any pain or past injuries. Appendicular SMM, and Skeletal Mass Index（SMI）that was calculated from appendicular SMM by dividing the height of the subjects squared (kg/m2), were obtained from the BIA device (InBody 430, Biospace, Korea). For the 1RM measurement, a unilateral leg press resistance-training machine (HUR, Finland) was used. The measurement of 1RM was according to the American College of Sports and Medicine guidelines. The maximum load that the subject could lift only once with their dominant leg was defined as 1RM. Statistical Analysis: Normality of data was assessed by Shapiro-Wilk statistics. Correlations between dominant-leg SMM, SMI and 1RM were calculated using Pearson's product moment correlation coefficient. A simple regression analysis was used to predict 1RM from BIA variables that were significantly correlated with 1RM．The significance level was set at 0.05.
Results: Correlation between dominant-leg SMM and 1RM of leg press was very strong (r=0.83, P 0.01), and there was nearly perfect correlation between SMI and 1RM of leg press (r=0.93, P 0.01). The prediction models for 1RM of leg press derived from dominant-leg SMM and SMI were Y=8.68x +10.58, R2=0.78, and Y=15.03x + -31.43, R2=0.83 respectively.
Conclusion(s): Our results showed that the correlation between measurements obtained from BIA and 1RM of leg press were very strong and SMI could be used to accurately predict 1RM of leg press.
Implications: BIA can be used as an indirect method to predict 1RM of leg press for healthy subjects.
Keywords: 1RM, BIA, Prediction
Funding acknowledgements: Nil.
Purpose: The purpose of this study was to examine the relationship between measurements by BIA and 1RM, and also to examine the regression model for estimating 1RM from BIA measurements.
Methods: Study design: Observational cross sectional study. Subjects：A total of 30 healthy young Japanese subjects aged 28.3±4.0 years old (15 males, 15 females) participated in this study. The subjects were excluded from this study if they had any pain or past injuries. Appendicular SMM, and Skeletal Mass Index（SMI）that was calculated from appendicular SMM by dividing the height of the subjects squared (kg/m2), were obtained from the BIA device (InBody 430, Biospace, Korea). For the 1RM measurement, a unilateral leg press resistance-training machine (HUR, Finland) was used. The measurement of 1RM was according to the American College of Sports and Medicine guidelines. The maximum load that the subject could lift only once with their dominant leg was defined as 1RM. Statistical Analysis: Normality of data was assessed by Shapiro-Wilk statistics. Correlations between dominant-leg SMM, SMI and 1RM were calculated using Pearson's product moment correlation coefficient. A simple regression analysis was used to predict 1RM from BIA variables that were significantly correlated with 1RM．The significance level was set at 0.05.
Results: Correlation between dominant-leg SMM and 1RM of leg press was very strong (r=0.83, P 0.01), and there was nearly perfect correlation between SMI and 1RM of leg press (r=0.93, P 0.01). The prediction models for 1RM of leg press derived from dominant-leg SMM and SMI were Y=8.68x +10.58, R2=0.78, and Y=15.03x + -31.43, R2=0.83 respectively.
Conclusion(s): Our results showed that the correlation between measurements obtained from BIA and 1RM of leg press were very strong and SMI could be used to accurately predict 1RM of leg press.
Implications: BIA can be used as an indirect method to predict 1RM of leg press for healthy subjects.
Keywords: 1RM, BIA, Prediction
Funding acknowledgements: Nil.
Topic: Outcome measurement; Musculoskeletal; Research methodology & knowledge translation
Ethics approval required: Yes
Institution: Shinshu University School of Medicine
Ethics committee: the Committee for Medical Ethics
Ethics number: 3722
All authors, affiliations and abstracts have been published as submitted.
