Weighting The Swing: The Mechanical Changes That Emerge When Loads Are Applied To Baseball Bats

Abstract

Success in baseball batting relies on a union of swing power and accuracy. Off the field, training commonly employs weighted loads replicating hitting mechanics. On the field, immediately prior to a plate appearance, batters sometimes place a weighted ring on the bat to warm up their swing. Although common, these traditional training methods lack investigation. PURPOSE: To observe differences of baseball swing characteristics in response to applied bat resistance. METHODS: We tested 14 NCAA baseball athletes using Proteus technology (Proteus Motion, USA). Participants completed 5 sets of 6 swings at increasing loads of magnetic resistance. Each set increased in weight by 2 lbs, ranging from 1-9 lbs. Measurements computed by Proteus were peak power, peak force development rate (PFDR), braking, consistency, endurance, velocity, and range of motion (ROM). Paired-samples t-tests compared swing characteristics of the 1 lb resistance to the mean of 3, 5, 7, and 9 lb. MANOVA with repeated measures observed the differences of swing variables in response to resistance increases. Linear regression tested the effect of different loads on performance parameters. RESULTS: The 1 lb resistance differed from the mean resistance in peak power (p<0.001), PFDR (p<0.001), braking (p<0.001), ROM (p=0.017), and velocity (p=0.063), but not in consistency (p=0.110) or endurance (p=0.375). The mean values of consistency (p=0.985) and endurance (p=0.530) could not predict outcomes for 1 lb performance, but did predict ROM (p=0.002) and braking, power, PFDR, and velocity (p<0.001). As resistance levels increased, there were significant differences in swing power (F=317.297, p<0.001), PFDR (F=141.797, p<0.001), braking (F=91.011, p<0.001), ROM (F=6.067, p=0.013), and velocity (F=2.5122, p=0.039), but not measurements of consistency (F=0.911, p=0.480) or endurance (F=2.156, p=0.070). CONCLUSIONS: As bat resistance increased, players made acute responses that compromised recruitment characteristics (consistency and endurance). Training and warm-up techniques that employ loaded swings may alter mechanics accordingly.