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Medicine & Science in Sports & Exercise:
May 2003 - Volume 35 - Issue 5 - p S62
B-13G Free Communication/Thematic Poster Biomechanics and Rowing
Duffey, M J.1; Zatsiorsky, V1
Author Information
1The Biomechanics Laboratory, Pennsylvania State University, University Park, PA
Standard, body-weight pushups are one of the most common exercises performed. Incline (hands
elevated) and decline (feet elevated) pushups are also relatively common exercises; however, there is no
report in the literature of the load supported during either incline or decline pushups. The purpose of this
study was to determine the load supported by the upper extremities during these activities.
Sixteen subjects were recruited from a basic weight training course at Pennsylvania State University.
Subjects were asked to perform a single pushup in each of nine conditions: hands and feet on the floor
(HF), hands elevated at 30.5cm, 61cm, 91.5cm or 122cm from the floor (HE1-HE4) or feet elevated at the
same heights (FE1-FE4). Subjects were asked to pause for approximately 3s at the top and bottom of
each pushup while force data was collected using a force plate.
As subjects progressed from the highest HE condition to hands and feet on the floor (HE4 through HF),
load supported by the upper extremity increased an average of 13.5% Body Weight (BW) for each
condition (HE4 12.4 ± 2.1, HE3 24.0 ± 3.2, HE2 41.3 ± 3.7, HE1 57.6 ± 3.7, HF 66.6 ± 2.8.) As the
subjects performed the FE conditions however, each increase in elevation resulted in an average
increase of only 1.2% BW (FE1 72.4 ± 2.1, FE2 73.9 ± 2.1, FE3 74.5 ± 2.4, FE4 76.1 ± 3.7).
The investigators expected a linear relationship between elevation height and load supported for all of the
conditions. There was a strong relationship between load and elevation for the HE4 through HF
conditions (R2 = .97). For the FE trials, however, there was a different and much weaker relationship
between foot elevation and load (R2 = .21). This suggested that an alternative strategy was developed by
the subjects in this study for the FE trials. Follow-up testing of a subset of the subjects indicated that
subjects were able to change the relationship between foot height and load supported by altering ankle
and hip position.
The purpose of this study was to determine the vertical and lateral forces applied to the bar during a maximal and a submaximal effort bench press lifts. For this study, 10 male and 8 female recreational lifters were recruited (mean height: 1.71 ± 0.08 m; mass: 73.7 ± 13.6 kg) and were asked to perform a maximal and submaximal (80% of maximal lift) bench press. These lifts were performed with a bar instrumented to record forces applied to it, via the hands, in the vertical direction and along the long axis of the bar. To determine the position of the bar and timing of events, 3D kinematic data were recorded and analyzed for both lifts. The subjects in this study averaged a maximal lift of 63 ± 29 kg (90 ± 31% bodyweight). The peak vertical force was 115 ± 22% (percentage of load), whereas for the submaximal condition it was 113 ± 20%; these forces were statistically different between conditions; they were not when expressed as a percentage of the load (p > 0.05). During all the lifts, the lateral forces were always outward along the bar. The lateral force profile was similar to that of the vertical force, albeit at a lesser magnitude. During the lift phase, the peak lateral force was on average 26.3 ± 3.9% of the vertical force for the maximal lift and 23.7 ± 3.9% of the vertical force for the submaximal lift. Given that the amount of force applied laterally to the bar was a similar percentage of vertical force irrespective of load, it appears that the generation of lateral forces during the bench press is a result of having the muscles engaged in generating vertical force.
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