A COMPARISON OF RESISTED AND ASSISTED SPRINT TRAINING IN COLLEGIATE SPRINTERS

Sprint time (ST) is the product of stride length (SL) and stride rate (SR). Increases in either of these variables results in speed improvement. Purpose: To compare resisted (RST) and assisted sprint training (AST) on sprint performance. Methods: Twenty (10 male, 10 female) collegiate sprinters and hurdlers were randomly divided into two training groups: RST (age: 21.81.8yrs, height: 1.730.10m, mass: 69.512.8kg) and AST (age: 22.22.4yrs, height: 1.760.10m, mass: 69.19.9kg). Each group trained 3 days/week for 6 weeks. The RST group used a combination of weighted sled pulls, uphill sprinting and depth jumps. The AST group combined downhill running, towing, sprint ladders and single leg bounds. Prior to and following the training interventions SL and ST (10 meter sprint time) were recorded at sprint distances of 30m, 60m, and 120m during the last 10 meters of each sprint distance. Pre-post training ST and SL were compared within training groups at each sprint distance using paired t-tests. Additionally, a gain score was calculated by taking the difference between the post and pre test scores. The gain scores for SL and ST were compared between training groups via independent t-tests at each sprint distance. Results: For the RST 30m, ST (1.180.08s vs 1.140.08s, p<0.01) and SL (2.060.08m vs. 2.091.14m, p<0.01) were significantly improved. For the AST, 30m ST (1.190.08s vs. 1.180.08s, p<0.01) and SL (2.100.13m i Corresponding Author: Mark DeBeliso Department of Kinesiology and Outdoor Recreation, Southern Utah University, 351 W. University Blvd., Cedar City, UT 84720, 435 – 586 – 7812, markdebeliso@suu.edu Murray, J., Harris, C., Adams, K. J., Joseph Berning, J., DeBeliso, M. A COMPARISON OF RESISTED AND ASSISTED SPRINT TRAINING IN COLLEGIATE SPRINTERS European Journal of Physical Education and Sport Science Volume 3 │ Issue 7 │ 2017 25 vs. 2.110.13, p=0.04) were significantly improved. No improvements in ST or SL were detected for either the RST or AST groups at the 60m sprint distance. For the RST 120m, ST (1.130.07s vs. 1.120.08s, p<0.01) was significantly improved. For the AST 120m, ST (1.120.07s vs. 1.110.07s, p<0.01) and SL (2.300.08 vs. 2.330.08, p<0.01) were significantly improved. At the 30M interval, the RST demonstrated significant improvements in SL and ST as compared to the AST (p<0.01). However, at the 120M interval, the AST demonstrated a significant improvement in SL as compared to the RST (p<0.01). Conclusion: Within the parameters of this study, RST and AST methods have proven effective at improving sprint performance. It appears that RST protocols may be of greatest benefit for improving sprint performance at shorter distances, while AST protocols may be of greater benefit at longer sprinting distances.


Introduction
Speed is a function of stride length multiplied by stride rate (S=SL x SR). To improve running speed through training, the training mechanism should improve SL, SR, or both. Typically, training mechanisms to improve sprinting speed involve some type of resisted sprint training (RST) where sprinting is done against a resistance. RST is done to impact leg strength and power and subsequently, improve stride length. Another approach to sprint training involves training at supra-maximal speeds, where the training mechanism is assisting the runner or Assisted Sprint Training (AST). RST   improved SR and overall running speed, the hope is that muscle memory will allow the athlete to take these gains to the flat running surface. Towing is a common form of assisted sprinting used quite often in track and field. In a study conducted by Gervais and LeBlanc (2004), ground support time was found to be significantly shorter in assisted sprinting. In this drill, the athlete was harnessed to a pulley system that was attached to another athlete standing 10 meters in front of the harnessed athlete. As the front athlete accelerated the athlete, being towed was forced by the pulley system to accelerate at a faster rate than the first athlete in order to keep up. This version of overspeed training allows the athlete to train at speed intensities above what is achievable independently.
The purpose of this study was to compare Resisted Sprint Training using a combination of RST modalities with Assisted Sprint Training using multiple AST modalities relative to sprint performance and kinematics (SR and SL). It was hypothesized that both training modalities would improvements in sprint speed and that the AST would lead to superior improvements in SR while RST would lead to greater gains in SL.

Participants
The participants for this study were a convenience sample of male and female collegiate track and field athletes that compete in the sprint and hurdle events at the NCAA Division I level. Permission from the head coach was granted prior to the study.
Student athletes were asked to volunteer for the study. Permission from the Institutional Review Board was obtained before conducting any training or assessments of the participants. Prior to engaging in any testing each of the participants signed an informed consent form that had been previously approved by the Institutional Review Board of Southern Utah University.

Instruments and Apparatus
The study training and testing sessions were conducted at the Athletic Complex at Southern Utah University ( Figure 1). Equipment necessary to conduct this study included Accusplit 601X hand held stopwatches (Accusplit, Pleasanton, California, USA), a standard video camera, and a running track. The running track was marked in three separate 10 meter zones in increments 10 centimeters. The first was a 30 meter sprint, with the final 10 meters timed and measured for SL. The second was a 60 meter sprint, with the final 10 meters timed and SL measured. Finally, the participants performed a 120 meter sprint with the final 10 meters timed and SL measured.

Procedures
The study initiated with a briefing session to address any comments or concerns posed by the participants. Next age, height and weight were recorded. Pre training assessment of the dependent variables was then conducted as described below (see Protocol for Assessing SR, SL, and Running Speed). The pre training assessment was conducted during the pre-competitive training phase ensuring the participants were properly conditioned. Following the pre training assessment session, the experimental groups (RST and AST) were constructed using a stratified random process assuring both experimental groups were balanced for gender (5-female and 5-male per experimental group).
Once divided into one of two experimental training groups the athletes performed training techniques thought to be beneficial to one of two areas, stride length (SL), and stride frequency (SR). Drills for SL included sleds pulling, running uphill, and depth jumps. For the purposes of this study, the sleds were weighted with 20% of the athlete's body weight to insure an equal work load for all involved and to allow the Drills used for SR included downhill running, towing on a cable/pulley system, use of a sprint ladder and bounding. The following independent variables were all used for stride frequency training. They included downhill running, sprint ladders, towing, and single leg bounding. Downhill running was conducted using a hill of at ≈ 3% grade for a distance of 50 meters (6 sets, total of 300 meters). In the towing drill, the athlete was harnessed to a pulley system that was attached to another athlete standing 10 meters in front of the harnessed athlete. As the front athlete accelerated the athlete The intervention period of the study lasted 6 weeks. Prior to each training and assessment session, a dynamic warm-up was performed as stated below. Each group also continued with their regularly scheduled training program including, strength training, interval training, and technical work (held constant between experimental groups). Figure 2 represents the specific training program for each experimental group (modality, frequency, and intensity). The PI was the participant's track coach and was present for all training sessions and conducted the pre and post study DV assessments.

Dynamic WU
The DYN WU took approximately 10-15 minutes to complete and consisted of a series of jogging movements (total 1000 meters) that included:

Protocol for Assessing SR, SL, and Running Speed
Prior to training each athlete participated in a pre-test to determine their stride frequency, stride length and running speed for sprint distances of 30, 60, and 120 meters (M). The researcher used a stop watch to time the participants running speed in each of three sprint distances during the last 10M. SR and SL were assessed during the final 10M of each of the three sprint distances. These measurements were made with the athlete running over a section of track that was 10M long and marked every 10 centimeters. This 10M section of the track was videoed from the sagittal plane for the assessment of SR and SL. SL was measured from toe contact of one limb to the next successive toe contact of the same limb. SR was determined using the formula SR=S/SL. Two testing trials were performed at each distance with the fastest time for each trial being used for analysis. All of the sprint trials were conducted during the same day in sequential fashion (i.e. 30M followed, 60M, and finally 120M) separated by 5-10 minutes. The pre and post-test assessments followed the same order and procedures to ensure accuracy in testing and familiarity for the participants.

Reliability
The reliability of short sprints has been reported to range from r=0.89-0.97 (Miller, 2012).
The reliability of handheld timing devices has also been reported to range from ICC=0.90-0.97. The concurrent validity between electronic and hand held devices is considered very high (ICC=0.98) (Mayhew et al., 2010). Sagittal plane video analysis of running mechanics such as foot strike patterns is considered highly reliable (Bertelsen, Jensen, Nielsen, Nielsen, & Rasmussen, 2013).

Statistical Analysis
The dependent variables (DVs) in this study were running speed, SR and SL at sprint distances of 30, 60, and 120 meters. The DVs were compared within each experimental group (RST, AST) with paired t-tests. A gain score was calculated for each DV (post-pre score) and compared between experimental groups with an independent t-test. For the purpose of statistical significance alpha was ≤0.05.

Twenty collegiate track athletes (sprinters and hurdlers) participated in this study
where each experimental group (AST and RST) was comprised of 5-males and fivefemales. Table 1 provides participant descriptive information of height, body mass and age.   Speed-meters/seconds, SR-stride rate (Hz), SL-stride length (meters). *significant differences pre-post within groups p<0.05; #-significant difference in gain score between groups p<0.05. Table 2 provides pre and post DV assessment data for both the AST and RST experimental groups. Significance improvements (p<0.05) for the DVs within the AST were as follows: • SL over 30M; • SR over 30M; • SL over 120M; • SR over 120M; • 10 meter time (running speed) over 30M; • 10 meter time (running speed) over 120M.
Significance improvements (p<0.05) for the DVs within the RST were as follows: • SL over 30M; • SR over 30M; • SR over 120M; Significance improvements (p<0.05) for the DVs gains scores were found between the RST and AST group were as follows: • SL over 30M (Greater for RST); • SL over 120M (Greater for AST).

Discussion
The main findings in this study included an increase in running speed at 30 meter and 120 meters following both the resisted and assisted sprint training. This was done to ensure that the participants were in good physical condition, as well as motivated to perform well on the testing. The post-testing took place one week before the outdoor conference championship meet, also ensuring that the participants were motivated and in peak condition. The timing of the post-test also allowed for those participants who did not travel to the conference championship meet to take place in the testing.
As with most studies that use competitive athletes, a limitation in this study was that of sample size. The research was limited to just one collegiate track and field team. This is admittedly a very small sample of the 300 plus universities in the country.
However, it would have proved to be extremely difficult to convince other collegiate coaches to alter their training regimens in order to fit the research protocols of this study. The second limitation was the age of the subjects participating in the study (age range of 18-26). While this limitation could be considered an issue, the majority of collegiate track and field athletes fall directly into this same age bracket. This is not to say that these results would not be beneficial to high school age athletes or even post collegiate competitors While this study has shown how valuable RST and AT can be to improved sprint success, there is no way to know which training variable used within each experimental training group (RST or AST) was most responsible for the gains made. Further studies would need to be done comparing the specific improvements from each of the resisted training variables (weighted sleds, uphill sprinting and depth jumps) as well as the assisted training variables (towing, downhill sprinting, single leg bounding and sprint ladders) in order to provide a more precise measure of the effects of each variable independently.

Practical Application
This study found a significant impact of RST and AST with regards to improving SL at specific distances, as well as improved 10 meter sprint times over specific distances.
Similar training used for the express purpose of improving stride length or 10 meter sprint times may also elicit the desired results. These training methods, used along with a properly designed periodized resistance training program, will most likely bring about positive results in the college age track and field sprint athlete. Comparable results might be expected if a similarly designed training program were used for high school aged athletes as well as post-collegiate or elite athletes.