Association Between Maximal Bench Press Strength and Isometric Handgrip Strength Among Breast Cancer Survivors

Objective: To characterize the relationship between 1-repetition maximum (1-RM) bench press strength and isometric handgrip strength among breast cancer survivors. Design: Cross-sectional study. Setting: Laboratory. Participants: Community-dwelling breast cancer survivors (N=295). Interventions: Not applicable. Main Outcome Measure: 1-RM bench press strength was measured with a barbell and exercise bench. Isometric handgrip strength was measured using an isometric dynamometer, with 3 maximal contractions of the left and right hands. All measures were conducted by staff with training in clinical exercise testing. Results: Among 295 breast cancer survivors, 1-RM bench press strength was 18.2 +/- 6.1kg (range, 2.2-43.0kg), and isometric handgrip strength was 23.5 +/- 5.8kg (range, 9.0-43.0kg). The strongest correlate of 1-RM bench press strength was the average isometric handgrip strength of both hands (r=.399; P<.0001). Mean difference analysis suggested that the average isometric handgrip strength of both hands overestimated 1-RM bench press strength by 4.7kg (95% limits of agreement, -8.2 to 17.6kg). In a multivariable linear regression model, the average isometric handgrip strength of both hands (beta=.31; P<.0001) and age (beta=.20; P<.0001) were positively correlated with 1-RM bench press strength (R-2=.23). Conclusions: Isometric handgrip strength is a poor surrogate for 1-RM bench press strength among breast cancer survivors. 1-RM bench press strength and isometric handgrip strength quantify distinct components of muscular strength. (C) 2016 by the American Congress of Rehabilitation Medicine