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C-18 Free Communication/Slide - Resistance Training: MAY 28, 2009 8: 00 AM - 10: 00 AM ROOM: 3AB

Maximal Force Generation In The Bench Press During Concentric And Eccentric Actions

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May 28 9:15 AM - 9:30 AM

Ho, Jen Yu; Fragala, Maren S.; Thomas, Gwendolyn A.; Volek, Jeff S.; Kraemer, William J. FACSM

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Medicine & Science in Sports & Exercise: May 2009 - Volume 41 - Issue 5 - p 63
doi: 10.1249/01.mss.0000353462.75436.37
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The purpose of this investigation was to characterize upper body concentric and eccentric strength performance in men and women. 24 men (22.9 yrs+2.8;177.9+18.2 cm; 82.2+7.1 kg) and 23 women (21.5 yrs+2.5;164.5+15.4 cm; 65.3+10.3 kg) gave written informed consent to participate in the study. A Dyformon /ABLE II (D/AII)instrument (Exerbotics, LLC, McPhearson, KS) monitored three coordinating subsystems: the electromechanical impingement exerciser, the force and position monitoring sensors, and the computer control and recording system was used to record data. Maximal concentric peak force and position of peak force were collected at three different velocities (0.10 m.s-1; 0.20 m.s-1;0.28 m.s-1). Test retest reliability demonstrated ICC of Rs>0.92. Significant correlations (r's from 0.78 to 0.95) were observed between the 1 RM bench press (Plyometric Power System, Lismore Australia [smith machine]) and the D/AII instrument for various peak forces indicating a high similarity between the measures. Men demonstrated significantly (p < 0.05) higher forces in peak forces in absolute terms (e.g. CON, Men: 0.10 m.s-1=1300.4+294; 0.20 m.s-1 = 1272.6+302 0.28 m.s-1=1157.9+281; Women: 0.10 m.s-1=712.76+164;0.20 m.s-1 =671.5+186; 0.28 m.s-1 =573.25+143) but the same response were see when corrected relative to body mass, and relative to fat free mass. While the ECC/CON force ratio has been shown to be higher in women in prior studies of single joint movements, we showed no differences between men and women at any of the test velocities in the bench press. Significant differences between genders in the concentric position of peak force were seen at 0.28 m.s-1and 0.20 m.s-1 testing velocities. The occurrence of the position of peak force near the top of the range of motion along with slower women's rate of force development than men shows that the characteristics of the lift differ in both muscle actions. These data give novel insights into upper body bench press exercise characteristics in men and women using a robotic testing system. These data demonstrate that sticking points and the pattern of forces over the range of motion are different between men and women in maximal effort concentric and eccentric phases of the bench press exercise.

© 2009 American College of Sports Medicine