Intra-Session Reliability and Predictive Value of Maximum Voluntary Isometric Contraction for Estimating...

Area of Science:

• Gerontology
• Exercise Physiology
• Biomedical Engineering

Background:

• Aging leads to decreased muscle strength, impacting functional independence in older adults.
• Assessing lower limb muscle strength is crucial for maintaining mobility and quality of life.
• Existing methods like maximum voluntary isometric contraction (MVIC) and one-repetition maximum (1RM) have limitations in older populations.

Purpose of the Study:

• To determine the intra-session reliability of MVIC for knee extensors in older women.
• To analyze the correlation between MVIC and 1RM in this demographic.
• To develop a predictive model for estimating 1RM from MVIC.

Main Methods:

• A randomized split-sample design was used with 82 women aged 60-69 years.
• Participants performed two MVIC trials and one 1RM test on a leg extension machine.
• Intraclass correlation coefficient (ICC), SEM, and MDC were calculated for reliability; linear regression for prediction.

Main Results:

• MVIC showed excellent intra-session reliability (ICC=0.96, SEM=4.3%, MDC=11.9%).
• A strong correlation was found between MVIC and 1RM (R²=0.618).
• The predictive equation (1RM = [0.932 × MVIC] - 3.852) had a prediction error of 13.4%.

Conclusions:

• MVIC is a highly reliable and practical measure for assessing knee extensor strength in older women.
• While MVIC is reliable, its predictive accuracy for 1RM is currently limited.
• Further research is needed to enhance predictive models by including additional physiological variables.