Body Mass and Femur Length Are Inversely Related to Repetitions Performed in the Back Squat in Well-Trained Lifters

Cooke, DM, Haischer, MH, Carzoli, JP, Bazyler, CD, Johnson, TK, Varieur, R, Zoeller, RF, Whitehurst, M, and Zourdos, MC. Body mass and femur length are inversely related to repetitions performed in the back squat in well-trained lifters. J Strength Cond Res 33(3): 890-895, 2019-The purpose of this research note was to examine whether relationships existed between anthropometrics (body mass, body fat percentage BF%, and femur length) and descriptive characteristics (age and sex) with repetitions performed to failure at 70% of 1 repetition maximum (1RM) in the back squat. Fifty-eight subjects (males = 43, females = 15; age: 23 ± 3 years, training age: 5.5 ± 2.5 years, body mass: 80.65 ± 16.34 kg, BF%: 10.98 ± 3.53%, and femur length: 47.1 ± 2.6 cm) completed a 1RM squat followed by one set to failure at 70% of 1RM. Total repetitions performed at 70% of 1RM were 14 ± 4 (range: 6-26). Bivariate correlations showed significant inverse relationships between body mass (r = -0.352, p = 0.003), BF% (r = -0.278, p = 0.014), and femur length (r = -0.265, p = 0.019), with repetitions performed. No significant relationships existed between age and sex (p > 0.05), with repetitions performed. All these variables entered into a standard multivariate regression. The model R was 0.200, and body mass had the largest influence (p = 0.057) because relative importance analysis demonstrated body mass to contribute to 43.87% of the variance (of the R) in repetitions performed. No other variable was significant or approached significance (p > 0.05). Our results reveal that body mass, BF%, and femur length all are inversely related to repetitions performed at 70% of 1RM in the back squat.