Multivariate analysis in the maximum strength performance.

Area of Science:

• Sports Science
• Human Physiology
• Biomechanics

Background:

• Muscle morphology and anthropometry are crucial factors influencing maximal force production.
• Understanding the relationship between muscle characteristics and strength performance is vital for training and performance optimization.
• Previous research has explored these relationships, but further analysis is needed to identify key predictors.

Purpose of the Study:

• To explore anthropometrical and morphological muscle variables related to one-repetition maximum (1RM) performance.
• To analyze the predictive capacity of these variables on force production.
• To identify the most relevant muscle characteristics for predicting strength in untrained individuals.

Main Methods:

• Exploratory analysis involving 50 active males.
• Data collection included vastus lateralis muscle biopsy, quadriceps magnetic resonance imaging (MRI) for cross-sectional area (CSA), body mass assessment, and 1RM leg-press testing.
• K-means cluster analysis and stepwise multiple regressions were employed to analyze relationships between variables.

Main Results:

• Cluster analysis identified distinct high strength performance (HSP1RM) and low strength performance (LSP1RM) groups.
• Quadriceps muscle CSA was the most significant variable differentiating the strength groups.
• For all participants and the LSP1RM group, both CSA and muscle fiber type II percentage predicted 1RM performance (Adj R2=0.35 and 0.25, respectively).
• For the HSP1RM group, only CSA predicted 1RM performance (Adj R2=0.38).

Conclusions:

• Muscle cross-sectional area (CSA) is the most critical anthropometrical and morphological variable for predicting force production (1RM performance) in individuals without prior strength training.
• Muscle fiber type II percentage also contributes to predicting strength, particularly in lower-performing groups.
• These findings underscore the importance of muscle size in determining maximal strength capacity.