Using a Horizontal Leg Press to
Measure Indices of Lower Body Power
Derek Ferley, PhD
Director of Sports Science Research
Avera Sports
Agenda
•
•
•
•
Traditional Tests of Power
The Plyo Press and 3PQ Testing
Reliability Study of the 3PQ
Methods
• Results
• Summary
• Future Considerations
• Acknowledgements
Traditional Tests of Power Output
• Vertical jump
• 1 repetition
• 30 s jump test
• Standing long jump
• 5 Hop Test
• Both-R-L-R-L-B
• Margaria Kalaman Stair Test (1968)
• Pros and Cons
• Isokinetic Dynamometer
• Peak Power
• Average Power
• Wingate Cycle Test
• Peak Power—5 s
• Relative Power—Peak power/kg
• Fatigue—Difference btwn highest and lowest 5
s power output ÷ by highest * 100
• https://www.youtube.com/watch?v=euaKhOAn_A
• Pros and Cons
The Plyo Press
• Athletic Republic recently developed the
Plyo Press Power Quotient (3PQ)
• A horizontal leg press with bilateral 300 lbs.
weight stacks and 96” rails
• Sled and foot plate are at 16⁰ from level and
perpendicular, respectively
• AMTI force plate 29” wide x 24” high force
mounted to frame
• Unimeasure linear velocity transducer (to
measure displacement and its speed)
• Custom-designed software—Accupower 2.0
1-leg and 2-leg Plyo Press Jumping
• 2-leg Plyo Press Jumps
• 1-leg Plyo Press Jumps
Methods—Study Design
• Experimental Approach
• A randomized repeated measures
study design
• Within-subject reliability and
comparisons were made between
dependent variables and test
conditions
• Participants completed the same
testing procedures on three separate
occasions
• Familiarization session + 2 others
• Test Conditions
• Two legs
• 100% BW or 120% BW
• One leg
• 50% BW or 80% BW
• Dependent Variables
•
•
•
•
•
•
Maximum force (N)
Maximum (+) and (-) power (W)
Average (+) and (-) power (W)
Average (+) and (-) work (J)
Rate of power development (W/s)
% Fatigue (+) and (-)
Methods—Participants
• Participants
• 30 total
• Primarily Division II baseball and softball
players
• 26 of 30
• Inclusion criteria
• Ages 18-25
• Willing to complete 3 test sessions over
approximately 3 weeks
• Exclusion criteria
• Current or recent (<3 months) lower body
injury
• Evidence of other medical conditions which
preclude performing intense exercise
• Pregnancy
Subject
Characteristics
Mean ± SD
(n = 30)
Age (y)
20.6 ± 1.5
Body mass (kg)
79.2 ± 12.6
Height (cm)
175.9 ± 7.6
66.3 ± 13.7
Vertical Jump (cm)
Number of years
weight training
experience (y)
(M): 74.0 ± 11.2; (F): 53.1 ±
4.5
6.6 ± 1.5
Procedures
• We met with University of Sioux Falls
baseball and softball teams prior to
practice sessions to invite them to
participate in the investigation
• Those meeting criteria and willing to
participate reported for testing on 3
separate occasions separated by
approximately 1 week each.
• The investigation took place JanuaryFebruary 2016.
• Testing Protocol
• Test conditions grouped as “Gold” and
“Non-Gold”
• “Gold” conditions
• 1-leg = 80% BW
• 2-leg = 120% BW
• “Non-Gold” conditions
• 1-leg = 50% BW
• 2-leg = 100% BW
• All tests performed as:
• R-leg, L-leg, B-legs; Rest 10 min; Repeat
with other condition
• Participants were thoroughly warmed up
prior to each session
• Test conditions were randomly chosen
during each session by flipping a card
Testing Sessions
• Session 1 served as a familiarization
session
• Prior to testing the investigative team
determined each participant’s:
• Body weight
• Vertical jump
• Plyo Press seat setting
• Metatarsal heads in line with shoulder
and knee angle at ~90◦
• Testing Instructions
• 1-leg tests lasted 20 s
• 2-leg tests lasted 30 s
• Participants were instructed to jump as
high and explosively as possible
throughout the test
• Participants received verbal
encouragement throughout each test
• Test sessions 2 and 3 were performed
in a similar manner using the same
seat setting
Statistical Analysis
• The statistical analysis program JMP was used
• Descriptive statistics for each outcome variable were determined
• Means
• Standard deviations
• ICCs
• A one-way ANOVA was used to assess reliability of trials
• Student’s T-tests were used to determine differences between conditions
• A significance level of 0.05 was used
Results—Outcomes during a 30 second 2-leg jump test using 100% body weight
Outcome Measure (
Trial 1 (n = 30)
Trial 2 (n = 30)
Trial 3 (n = 30)
ICC
Max Force (N)
1919.4 ± 442.6
1953.2 ± 402.1
1991.9 ± 403.9
0.96
Max (+) Power (W)
2150.8 ± 658.7
2207.9 ± 659.9
2244.2 ± 674.4
0.99
Max (-) Power (W)
1543.3 ± 507.2
1576.8 ± 506.5
1627.6 ± 484.6
0.97
Avg (+) Power (W)
1803.5 ± 543.4
1879.3 ± 563.7
1934.3 ± 574.7
0.98
Avg (-) Power (W)
1209.2 ± 393.9
1262.2 ± 411.0
1311.8 ± 400.3
0.97
Avg (+) Work (J)
459.9 ± 127.5
474.9 ± 130.1
473.5 ± 131.9
0.98
Avg (-) Work (J)
343.6 ± 91.2
353.1 ± 93.5
350.2 ± 97.9
0.98
4660 ± 2097.5
4996.6 ± 2359.0
5292.6 ± 2456.6
0.92
% Fatigue (+)
24.3 ± 12.8
24.5 ± 15.4
23.9 ± 15.2
0.97
% Fatigue (-)
26.3 ± 15.3
25.2 ± 16.2
23.9 ± 16.5
0.94
RPD (W/s)
Results—Outcomes during a 30 second 2-leg jump test using 120% body weight
Outcome Measure (
Trial 1 (n = 30)
Trial 2 (n = 30)
Trial 3 (n = 30)
ICC
Max Force (N)
2017.7 ± 464.4
2055.9 ± 444.8
2093.8 ± 415.5
0.97
Max (+) Power (W)
2128.2 ± 671.8
2119.7 ± 622.0
2148.07 ± 606.3
0.98
Max (-) Power (W)
1589.3 ± 499.2
1556.6 ± 499.9
1606.7 ± 455.3
0.97
Avg (+) Power (W)
1737.3 ± 569.6
1780.2 ± 556.3
1832.8 ± 541.2
0.98
Avg (-) Power (W)
1241.7 ± 413.6
1242.3 ± 422.2
1296.5 ± 369.2
0.97
Avg (+) Work (J)
476.2 ± 154.5
464.8 ± 135.8
467.5 ± 126.6
0.98
Avg (-) Work (J)
368.7 ± 119.1
351.6 ± 100.5
356.7 ± 95.9
0.98
4313.9 ± 2091.9
4788.9 ± 2760.2
5055.4 ± 2354.9
0.92
% Fatigue (+)
29.8 ± 14.9
30.1 ± 15.4
28.7 ± 15.4
0.96
% Fatigue (-)
30.2 ± 16.6
28.9 ± 16.6
26.3 ± 16.4
0.96
RPD (W/s)
Results—Outcomes for right leg during a 20 second jump test using 50% body weight
Outcome Measure (
Trial 1 (n = 30)
Trial 2 (n = 30)
Trial 3 (n = 30)
ICC
Max Force (N)
1217.9 ± 350.9
1266.9 ± 347.9
1267.3 ± 358.5
0.95
Max (+) Power (W)
1147.4 ± 346.2
1187.0 ± 343.6
1198.7 ± 364.6
0.98
Max (-) Power (W)
793.4 ± 284.4
839.1 ± 294.3
842.5 ± 290.0
0.96
Avg (+) Power (W)
960.5 ± 313.9
1030.4 ± 296.9
1049.0 ± 314.8
0.96
Avg (-) Power (W)
586.4 ± 203.0
639.2 ± 239.7
639.6 ± 223.5
0.95
Avg (+) Work (J)
267.9 ± 78.5
283.9 ± 72.5
273.5 ± 74.3
0.95
Avg (-) Work (J)
176.7 ± 58.2
187.7 ± 56.4
176.6 ± 49.6
0.95
2459.3 ± 1574.5
2691.6 ± 1617.1
2785.2 ± 1686.9
0.96
% Fatigue (+)
8.8 ± 9.3
9.8 ± 6.9
9.8 ± 6.4
0.66
% Fatigue (-)
3.7 ± 16.6
7.5 ± 12.9
4.9 ± 11.3
0.75
RPD (W/s)
Results—Outcomes for right leg during a 20 second jump test using 80% body weight
Outcome Measure (
Trial 1 (n = 30)
Trial 2 (n = 30)
Trial 3 (n = 30)
ICC
Max Force (N)
1390.0 ± 341.2
1398.9 ± 350.1
1439.4 ± 399.9
0.96
Max (+) Power (W)
1174.2 ± 378.9
1160.7 ± 336.1
1181.0 ± 346.7
0.98
Max (-) Power (W)
977.0 ± 322.3
940.8 ± 291.9
954.9 ± 309.0
0.95
Avg (+) Power (W)
986.5 ± 322.6
1004.5 ± 292.5
1036.9 ± 306.1
0.97
Avg (-) Power (W)
751.3 ± 243.5
738.9 ± 224.3
763.2 ± 239.7
0.96
Avg (+) Work (J)
306.7 ± 94.9
299.3 ± 88.4
296.7 ± 90.2
0.96
Avg (-) Work (J)
237.0 ± 74.0
221.2 ± 63.4
215.6 ± 60.9
0.96
2271.3 ± 1278.6
2458.6 ± 1452.2
2638.5 ± 1587.7
0.96
% Fatigue (+)
16.5 ± 7.3
16.4 ± 9.9
14.9 ± 7.1
0.62
% Fatigue (-)
14.1 ± 11.2
10.7 ± 10.7
12.4 ± 9.6
0.58
RPD (W/s)
Results—Outcomes for left leg during a 20 second jump test using 50% body weight
Outcome Measure (
Trial 1 (n = 30)
Trial 2 (n = 30)
Trial 3 (n = 30)
ICC
Max Force (N)
1233.5 ± 342.1
1297.5 ± 337.2
1318.0 ± 363.4
0.95
Max (+) Power (W)
1198.7 ± 393.8
1232.5 ± 373.5
1256.9 ± 399.6
0.98
Max (-) Power (W)
802.5 ± 268.9
858.6 ± 290.0
889.7 ± 292.7
0.96
Avg (+) Power (W)
1011.6 ± 314.1
1088.9 ± 336.6
1108.0 ± 340.7
0.97
Avg (-) Power (W)
619.0 ± 200.7
672.1 ± 247.0
686.8 ± 231.5
0.95
Avg (+) Work (J)
276.2 ± 77.4
285.9 ± 75.2
282.6 ± 80.9
0.95
Avg (-) Work (J)
175.8 ± 52.3
188.8 ± 51.7
180.7 ± 52.5
0.94
2661.8 ± 1611.7
2918 ± 1774.5
3018.2 ± 1803.1
0.98
% Fatigue (+)
12.2 ± 8.1
10.6 ± 7.8
13.2 ± 7.8
0.76
% Fatigue (-)
9.2 ± 8.4
8.3 ± 9.9
9.5 ± 10.5
0.85
RPD
Results—Outcomes for left leg during a 20 second jump test using 80% body weight
Outcome Measure (
Trial 1 (n = 30)
Trial 2 (n = 30)
Trial 3 (n = 30)
ICC
Max Force (N)
1392.7 ± 370.9
1400.7 ± 356.3
1477.7 ± 411.5
0.96
Max (+) Power (W)
1192.9 ± 413.9
1152.97 ± 354.9
1197.8 ± 355.8
0.98
Max (-) Power (W)
979.9 ± 362.2
972.0 ± 315.4
997.3 ± 307.1
0.96
Avg (+) Power (W)
1009.8 ± 351.6
983.0 ± 316.0
1060.7 ± 321.8
0.97
Avg (-) Power (W)
759.6 ± 267.7
741.9 ± 263.9
793.5 ± 253.6
0.97
Avg (+) Work (J)
307.7 ± 103.7
288.5 ± 91.9
295.6 ± 87.4
0.96
Avg (-) Work (J)
231.2 ± 77.9
219.6 ± 69.6
219.5 ± 64.5
0.97
2409.0 ± 1353.4
2608.7 ± 1625.8
2742.5 ± 1442.4
0.96
% Fatigue (+)
16.9 ± 6.2
17.1 ± 4.5
15.2 ± 5.5
0.65
% Fatigue (-)
14.0 ± 11.2
14.5 ± 10.0
13.7 ± 10.5
0.85
RPD (W/s)
Results—Positive Power vs. Body Weight During 2-Leg Jumping Using 100% and 120% BW,
respectively
2 Leg Positive Power vs Vertical Jump
100% Body Weight
2 Leg Positive Power vs Vertical Jump
120% Body Weight
4500.0
4000.0
4000.0
3500.0
3500.0
3000.0
2500.0
2500.0
Watts
Watts
3000.0
2000.0
2000.0
1500.0
1500.0
y = 40.53x - 444.76
R² = 0.6822
1000.0
y = 35.86x - 231.02
R² = 0.6607
1000.0
500.0
500.0
0.0
0.0
40.0
50.0
60.0
70.0
80.0
Vertical Jump (cm)
90.0
100.0
110.0
40.0
50.0
60.0
70.0
80.0
Vertical Jump (cm)
90.0
100.0
110.0
Summary
• Strong reliability among the 3 trials for all outcome measures during 1-leg and
2-leg jumping tests
• Exceptions were 1-leg (+) and (-) fatigue = less strong
• Significant differences in nearly all outcomes between 1-leg 50% and 80%
BW and 2-leg 100% and 120% BW
• Implications as to which approach is best? Or neither?
• Investigator observations: “Gold” standard conditions much more difficult for
female participants
Future Considerations
• A study to determine optimal load for power training when using the Plyo
Press
• Based on 1RM or %BW?
• Baker et al. (2001) reported jump squat power output maximized with loads 55-59% of
1RM full squat strength
• A comparative analysis of the Plyo Press, Jump Squat, Power Clean and
Vertical Jump
• Develop a database of normative values for gender and 1-leg and 2-leg
conditions
Acknowledgements
• The investigative team appreciates the time and efforts of the participants involved
in this investigation.
• We also appreciate the assistance of Avera Sports student intern Kipp Kinsley
(SDSU 2016 winter intern experience) who performed many of the assessments.
• Our investigative team also appreciates the support of Avera Sports and the Avera
Sports staff, including Whitnee Fester, Cameron Ditlevson, Colin Frommelt and
Kaitlyn Yoerg.
Thank You