Isolating The Effect Of Grip Strength On Exit Velocity In Male Baseball Players

Limited evidence suggests grip strength predicts bat speed and hitting distance. However, maturation, anthropometric variables, and muscular strength must be controlled to isolate this relationship. PURPOSE: To test the effect of grip strength on exit velocity in baseball players. METHODS: We enrolled 129 male baseball players for testing. We measured grip strength using a Jamar handgrip dynamometer, and assessed it in 3 positions: 0° shoulder abduction and 90° elbow flexion (0/90), 90° shoulder abduction and 90° elbow flexion (90/90), and overhead at 0° elbow extension (overhead). Mean and peak exit velocity were captured using a Trackman Launch Monitor. Age, height, weight, vertical jump power, and torso rotation power were used as controls. Kinematic assessments were captured using a Proteus device. Linear regression models tested the effect of grip strength in each position on exit velocity holding all confounders constant. RESULTS: Players were 15.5 ± 3.1 years of age, height was 69.2 ± 3.9 in, and weight was 157.1 ± 34.7 lb. Dominant 0/90 grip strength was 45.1 ± 12.9 kg, non-dominant 0/90 strength was 44.5 ± 12.5 kg, dominant 90/90 strength was 38.5 ± 12.3 kg, and dominant overhead strength was 42.1 ± 13.5 kg. Mean exit velocity was 74.8 ± 11.7 mph and peak exit velocity was 78.5 ± 9.6 mph. Holding constant all maturation variables (age, height, and weight), each additional kg of dominant 0/90 grip strength predicted an increase in peak exit velocity of 0.3 mph (p < 0.001; 95% CI: 0.161, 0.379). Similar results were found with non-dominant 0/90 strength (p < 0.001; 95% CI: 0.163, 0.400), dominant 90/90 strength (p < 0.001; 95% CI: 0.138, 0.399), and dominant overhead strength (p < 0.001; 95% CI: 0.151, 0.378). When adding muscle performance variables to the model, all assessments of grip strength retained significance (p < 0.001; β > 0.250). Mean exit velocity exhibited more modest effects. Holding maturation and performance variables constant, each kg of dominant 0/90 strength predicted an increase of 0.2 mph of mean exit velocity (p = 0.006; 95% CI: 0.068, 0.403). All other grip strength assessments were similar (p < 0.050; β > 0.200). CONCLUSION: Grip strength is a robust predictor of average and maximum exit velocity in baseball players. These effects were independent of age, height, weight, leg power, and rotational power.