Sled Towing Acutely Decreases Acceleration Sprint Time

Research Review: Sled Towing Acutely Decreases Acceleration Sprint Time.

By Sean Butler BS, CSCS, CES, DPT Student

Edited by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation: Wong, M. A., Dobbs, I. J., Watkins, C. M., Barillas, S. R., Lin, A., Archer, D. C., … & Brown, L. E. (2017). Sled towing acutely decreases acceleration sprint time. The Journal of Strength & Conditioning Research, 31(11), 3046-3051. ABSTRACT

Why is this study relevant:

Post-activation potentiation (PAP) is a phenomenon in which a muscle’s force is acutely increased as a result of its contractile history (1). Research suggests that while fatiguing muscle contractions may impair performance, non-fatiguing muscle contractions may enhance the performance of functional activity and sport (2-4). This 2017 study demonstrated that 30-m sprint times are enhanced after towing a sled loaded with 30% body mass; however, inter-set rest periods should be individualized. Human movement professionals should consider integrating sled pulling prior to sprint training and performance, and systematically determine ideal rest periods for use during competition.

Caption: International level women athletes competing in 100 m sprint race at ISTAF Berlin, 2006

International level women athletes competing in 100 m sprint race at ISTAF Berlin, 2006 - By André Zehetbauer from Schwerin, Deutschland - 100m B-Lauf S.Schielke192, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=19245303

Study Summary

Study Design	Quasi-experimental, repeated measures design
Level of Evidence	IIB Evidence from at least one other type of quasi-experimental study
Participant Characteristics	Demographics Number of participants: 20 Gender: male Height (+/- SD): 176.95 +/- 5.46 cm Weight (+/- SD): 83.19 +/- 11.31 kg Age (+/- SD): 22.3 +/- 2.4 years (range: 20-28 years) Inclusion Criteria: Active in a field sport at least twice a week for the past 6 months Exclusion Criteria: No lower body injuries in the last year
Methodology	Testing took place on 6 separate days at the same time each day Participants wore cleats for all testing sessions Grass levels were maintained at approximately 1.5 inches throughout data collection Day 1: Testing and Familiarization Body mass and height were measured Participants performed a dynamic warm-up which consisted of: 400-m jog 20-m A-skips 20-m high knees 20-m butt kicks 20-m cariocas 20-m back pedals 3 30-m sub-maximal sprints at 70, 80 and 90% of perceived maximal velocity, followed by a 5-minute recovery period. 2 x 30-meter maximal sprints (unloaded) were performed, separated by 5-minute rest intervals, to provide baseline measurements. Participants then underwent a familiarization session with a drag sled attached to a waist belt, using loads of 15, 20 and 30% of body mass. Participants randomly selected their rest periods for the upcoming training days. Days 2-6: Testing The Day 1 warm-up protocol was used on all testing days, followed by a 5-minute recovery period. Participants then sprinted 30-m while towing a sled loaded with 30% of their body mass, and then rested for 2, 4, 6, 8 or 12 minutes. After the rest interval, participants performed a maximal 30-m sprint (unloaded).
Data Collection and Analysis	Data Collection for Sprint Times: Sprint times were collected at 4 splits using wireless electronic timing gates (Brower Timing Systems, Draper, UT, USA) Sensors were attached to tripods and placed at the starting line, 5, 10, 20 and 30 meters. Participants began just behind the starting line, using a self-selected 2-point standing start position. Times were recorded for each day, and each participant’s best time was recorded for statistical analysis. Statistical Analysis SPSS version 23.0 was used for calculations Significance was set at p < 0.05 A 1x7 repeated-measures ANOVA was used to analyze total 30-m sprint time between conditions (Baseline, 2, 6, 8, 12 minutes rest, best time) A 2x4 (condition x split) analyzed baseline and best split times. A 1x5 repeated-measures ANOVA analyzed sled tow total 30-m sprint time between conditions (2, 4, 6, 8 and 12 minutes) Interactions and main effects were followed up with simple ANOVAs.
Outcome Measures	30 meter sprint times with split times at the following distances: 0-5-m 5-10-m 10-20-m 20-30-m Total 30m time
Results	Post-sled tow sprint times were significantly shorter than baseline sprints. Baseline = 4.55 +/- 0.18 seconds Best Time = 4.47 +/- 0.21 seconds Interactions showed significantly shorter times only during the 0-5-meter split. Individual 0-5 meter delta times between baseline and best times were calculated and revealed that 17 of 20 subjects “potentiated,” but at different rest intervals. 2 minutes - 9 participants 4 minutes - 5 participants 6 minutes - 0 participants 8 minutes - 2 participants 12 minutes - 1 participants
Our Conclusions	Post-activation potentiation (PAP) may be effective for acutely improving 30-meter sprint times, in large part by improving initial acceleration (drive phase). 75% of participants benefited from 30-meter sled drags loaded with 30% of body mass followed by a 2-4-minute rest period. 25% benefited from additional rest, implying individualization of rest periods may be necessary for some athletes.
Researchers' Conclusions	30-meter sled drags loaded with 30% of body mass, followed by rest periods of 2-12 minutes, acutely improve the initial 5-meter acceleration time in recreationally trained field sport athletes. Sled drags using 30% of body mass in conjunction with individualized rest periods are recommended for those aiming to acutely improve 5-meter acceleration time.

Review & Commentary:

This study investigated whether 30-meter sled drags loaded with 30% of body mass would elicit post-activation potentiation (PAP) and enhance 30 meter sprint performance. Additionally this study compared various rest periods and sprint split times. Previous research implied a need for individualization of rest periods (3 ); where as this study demonstrated that 75% of individuals may benefit from 2-4 minutes rest. Further, this study demonstrated that much of the benefit of PAP was elicited during the 0-5meter split time, implying enhanced initial acceleration (drive phase).

This study had several strengths, including:

Strength testing reliability was improved by using a standardized warm-up and familiarization session protocol (5).
A repeated measures design allowed athletes to act as their own control group; accounting for potential confounding variables (sleep, nutrition, training status and genetics).
To reduce the chance that fatigue or a “warm-up effect” could alter outcome measures, baseline sprint performance times were taken on a separate day.
The use of various rest periods added to the study design, demonstrating that sled drags with individualized rest periods may enhance sprint performance.
The study was performed on a grass field with commonly used equipment (sled and harness) improving applicability and practicality of the research findings.

Weaknesses that should be noted prior to clinical integration of the findings:

A small sample of only male athletes reduces the generalizability of the study
Only one load of 30% body mass was tested, and no baseline strength testing was performed. A previous study demonstrated that stronger individuals benefit more from PAP (3 ). Further research is needed testing different loads, and perhaps as a percent of 1RM, to determine ideal load for sled pulling.
Further research should compare the sled pull to other activities shown to be effective for PAP in the body research.

Why This Study is Important:

This study adds another exercise (sled-pulls) to the research tested repertoire of effective techniques for eliciting PAP. Further this study tested various rest periods and split times during post sled pull sprint performance. The study demonstrated that while individualization may be necessary for some athletes, the majority of athletes benefit most from a 2 – 4 minute rest period. Further, this study also showed that much of the benefit from a PAP warm up was noted during the 0-5 second split (initial acceleration/drive phase).

How the Findings Apply to Practice:

Human movement professionals working with track and field, and field sport athletes may add sled pulls to their repertoire as a more convenient exercise for PAP training on the field. Further, those training teams of athletes may use a 2 - 4 minute rest interval during training, with confidence that the majority of individuals will benefit most from this time period. In congruence with previous research, individualized rest times may be optimal for performance (3) and are recommended for competition preparation. The addition of sled pulls and a generally effective rest interval for groups are important practical applications human movement professionals working on fields/courts with teams.

Related to Brookbush Institute Content

The Brookbush Institute (BI) recommends the addition of PAP protocols to an integrated program with the intent of optimizing motion and performance. As an evidence-based, practical education company the BI will continues to compile all relevant research with intent of refining recommendations for PAP protocols. The findings from this study suggest that the BI should add sled pulls with 30% of body mass to a list of effective techniques for PAP, followed by a 2-4-minute rest period. This study suggests that 75% of individuals will benefit most from this rest period, while 25% of individuals may benefit from additional rest. The BI recommends using 2-4 minutes as a “general protocol” and for team training, but recommends individualized times for competition prep and/or one-on-one training. The BI hopes that future research will compare sled pull loads and distance, and further compare the various exercises shown to elicit PAP in pursuit of optimal practice.

Below are videos of similar exercises to those in this study:

Power Row Sled Video

Sled Push (Chest Power Exercise)

Bibliography:

Robbins, D. W. (2005). Postactivation potentiation and its practical applicability: a brief review. Journal of Strength and Conditioning Research, 19(2), 453.
Lorenz, D. (2011). Postactivation potentiation: An introduction. International Journal of Sports Physical Therapy, 6(3), 234.
Bevan, H. R., Cunningham, D. J., Tooley, E. P., Owen, N. J., Cook, C. J. and Kilduff, L. P. (2010). Influence of postactivation potentiation on sprinting performance in professional rugby players. The Journal of Strength & Conditioning Research, 24(3), 701-705.
Bishop, CJ., Tarrant, J., Jarvis, PT. and Turner, AN (2017). Using the split squat to potentiate bilateral and unilateral jump performance. The Journal of Strength & Conditioning Research, 31(8), 2216-2222.
Seo, D. I., Kim, E., Fahs, C. A., Rossow, L., Young, K., Ferguson, S. L., & Lee, M. K. (2012). Reliability of the one-repetition maximum test based on muscle group and gender. Journal of Sports Science & Medicine, 11(2), 221.
Cuenca-Fernández, F., López-Contreras, G., & Arellano, R. (2015). Effect on Swimming Start Performance of Two Types of Activation Protocols: Lunge and YoYo Squat. The Journal of Strength & Conditioning Research, 29(3), 647-655.

Questions, comments, and criticisms are welcomed and encouraged -

Sled Towing Acutely Decreases Acceleration Sprint Time

Research Review: Sled Towing Acutely Decreases Acceleration Sprint Time.

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