Limitations to this study could include:

• the Keiser equipment is a dynamic resistance machine and

the subject may achieve the desired (display) force output

at some random point within the ROM, thus for outcomes

average power may be more suitable than peak power

• such that the display value on the machine does not

accurately measure the peak power or force during the

movement this can alter the goals of % 1-RM

• caution must be used in interpreting power measures at

low forces due to ambient air pressure (14.7 psi)

Subjects: 18 men (age 24.2 ± 3.8 yr; body fat 15.5 ± 8.0 %) and 18 women

(age 22.4 ± 2.3 yr; body fat 26.5 ± 8.3 %) participated

Strength: upper- and lower-body one repetition maximal (1-RM) strength

was determined using a pneumatic bi-lateral chest press and leg press

device (Keiser Sport, Fresno, CA)

Force/Velocity: 6 repetitions at 5 different percentages of the subjects 1-RM

(30, 40, 50, 60, & 70% 1-RM) were completed in random order for both

exercises while the A420 electronics package measured speed and ROM

•A.V. Hill first described the curvilinear force-velocity relationship where

during concentric-isotonic contractions the muscle will contract at different

velocities depending upon the load applied

•Recent investigations have suggested that this relationship may be linear

due to neural or dampening effects of the non-contractile elements of whole

muscle during dynamic exercises

•The purpose of this experiment was to test this relationship during dynamic

whole body movements such as the leg and chest press.

Methods

T. Marcell, D. Mahler, & S. Lenz Department of Kinesiology

Background

Results

Limitations

Conclusions

1

2

3

4

5

The force-velocity relationship is

not curvilinear for the leg press or

chest press exercise

Funding Source:

CSU Stanislaus Research Fund

Figure 1. Force-velocity values (mean ± SD) for the young male and female subjects;

(A) upper-body and (B) lower-body (B) exercise.

The most important findings from this study were:

•force measures increased with increasing percentages of the

one-repetition maximum (% 1-RM) while velocity decreased

•these values for both the dynamic isotonic chest and leg

press were described by a both a linear and/or quadratic

relationship

•Peak force is inversely related to peak velocity for both the chest and leg press; see Figure 1

•Peak force and velocity were greater in men than women and were greater for the leg press than for the chest press

•One-way ANOVA (post-hoc) demonstrated that due to large SD significant differences for force measures varied; e.g., 30% was not

different than 40% but was different from 50% - 100%, 40% was not different than 30% or 50% but was different than 60% - 100%

•Nonlinear regression curve-fitting analysis demonstrated that a quadratic equation (r2 = 0.997-0.999) was only slightly better at

describing the relationship between force and velocity than a linear equation (r2 = 0.989-0.997)

A

B

Velocity (m/s)

0.0 0.5 1.0 1.5 2.0 2.5

Forc

e (N

)

0

500

1000

1500

2000

2500

3000

3500

Velocity (m/s)

0.0 0.5 1.0 1.5 2.0 2.5

Forc

e (

N)

0

500

1000

1500

Men

Women