Thirteen elite junior rugby league players took part in the investigation. All participants were engaged in a regular training program that utilised combined maximal strength and power training for at least one year and were able to squat a minimum of 1.5 x their body mass.
The study required the participants to complete one familiarisation and three experimental sessions in order to compare the acute effects of the back squat and the power clean on PAP responses during a sprint test. During the familiarisation session the subject 1RM in the power clean and back squat were determined. The three experimental testing sessions were then completed in a randomised order, at the same time of day over a 2-week period. During the experimental sessions, the participants were required to perform 20-m sprints before and 7 minutes after one of the two conditioning activities (one set of three back squat at 90 % 1RM, one set of three power cleans at 90 % of 1RM) or after a control condition.
Potentiation and Control Protocols
Two minutes after the determination of the baseline sprint, the participants performed one of the following activity: 1) one set of three back squats at 90 % 1RM, 2) one set of three power cleans at 90 % 1RM or 3) a control condition (one 20-m sprint). Following a 7-min recovery period, the post-measurement 20-m sprint was performed.
- There was a significant interaction (time × condition) effect for PAP during the sprint test (p <0.05). Post-hoc analyses revealed a significant improvement in 20-m sprint time, velocity and average acceleration after both the set of back squats and the set of power cleans with no significant changes observed after the control condition.
- The set of power cleans induced a significantly (p= 0.042; ES= 0.83) greater improvement in 20-m sprint time (3.05 ± 1.08 %) when compared to the set of back squats (2.16 ± 1.07 %).
- The improvement in velocity was significantly greater (p= 0.047; ES= 1.17) after the set of power cleans (3.22 ± 1.15 %) than after the set of back squats (2.25 ± 1.11 %). The improvement in average acceleration was also significantly greater (p= 0.05; ES= 0.87) after the set of power cleans (6.61 ± 2.36 %) than after the set of back squats (4.59 ± 2.26 %).
- The percent improvement in 20-m sprint time (i.e., PAP) had a large correlation with the relative 1RM back squat (r= 0.56; p= 0.04) and the relative 1RM power clean (r= 0.63; p= 0.02). Conversely, the absolute 1RM back squat (r= 0.49; p= 0.09) and the absolute 1RM power clean (r= 0.54; p= 0.06) were not significantly correlated to the improvement in the 20-m sprint time.
- 20-m sprint time displayed a large correlation to the relative power clean strength (r= -0.64; p= 0.02) and the relative back squat strength (r= -0.57; p= 0.04). The 20-m sprint time also displayed a large correlation to the absolute power clean strength (r= -0.62; p= 0.02) and the absolute back squat strength (r= -0.60; p= 0.03).
- Both the back squats and powers clean resulted in a significant PAP effect during a 20-m sprint performance test.
- Additionally, the magnitude of PAP response was significantly greater following the power clean conditioning activity. One set of three power cleans performed at 90 % 1RM resulted in a significantly (p= 0.042; ES= 0.83) greater PAP response (3.05 ± 1.08 %) when compared to the PAP response (2.16 ± 1.07 %) to three back squats performed at 90 % 1RM.
- The magnitude of PAP during a 20-m sprint was greater following the set of power cleans than the set of back squats may potentially be explained by the sprint start used and the kinematics associated with sprinting. The sprint start is thought to be highly dependent on ‘speed strength’ and maximal power production and the power clean allows for the production of high-forces at high-velocities resulting in higher power outputs. Conversely, the back squat allows the production of high-forces at low-velocities resulting in lower power outputs. Therefore, the execution of the set of power cleans might have allowed the participants to acutely produce a better acceleration than after the set of back squats, allowing them to run the 20-m distance quicker.
- 20-m sprint performance can be improved if one set of three back squats or power cleans performed at 90 % 1RM is performed 7 minutes prior to a maximal 20-meter sprint effort. Additionally, the magnitude of improvement is greater following a set of power cleans in comparison to a set of back squats.
The Back Squat and the Power Clean elicit Different Degrees of Potentiation. Seitz LB, Trajano GS, Haff GG. International Journal of Sports Physiology and Performance