There are many tools used to help an athlete improve speed, two things that I wanted to look at were sleds and weighted jackets. Weighted sled work is great for horizontal forces and seems to be a great way to work on form running as well. Many athletes incorporate weighted jackets or vests while sprinting, which seems logical, but what are the true benefits of these types of speed drills and do they really enhance sprint performance. This study looked at the effects of both weighted vests and weighted sleds. Clark, Stearne, Walts, Miller wanted to determine the effectiveness of these training methods on improving maximum sprint velocity (2010). Twenty individuals were placed into three different groups, weighted sled (WS), weighted vest (WV) and lastly, an unresisted (UR) group.
The timing system was set up to capture maximum velocity speed, so timing gates were set up between 18.3m to 54.9m. The sled resistance added load was set at 10% of the person’s body weight and loads of 18.5% was used for the weighted vest. The testing lasted seven weeks long and each group participated in training twice a week, along with three days a week of strength training. Training sessions with sled and vest lasted roughly 20 minutes with anywhere between 6-9 trails depending on the total volume of training.
The results didn’t show any statistical significant differences in running kinematics, such as stride length or stride frequency, while using WV or WS. Whereas, the pure sprint times did, of course, decrease due to the additional loading as well as a decrease was seen with average velocity when compared with pre-test UR times. Unfortunately, there was very little improvement in sprint times after training seven weeks with WS and WV. Statistically the authors did not see any significant advantages in maximum sprint velocity. What was seen as having more improvement in parameters was the UR group, “for the variables of sprint time and average velocity, effect size statistics suggested small post-training improvements for the UR group” (Clark et al., 2010, p. 3292). Therefore, concurrent training with weight may not be as beneficial as one might expect.
Reference
Clark, K. P., Stearne, D. J., Walts, C. T., & Miller, A. D. (2010). The longitudinal effects of resisted sprint training using weighted sleds vs. weighted vests. Journal Of Strength & Conditioning Research (Lippincott Williams & Wilkins), 24(12), 3287-3295 9p. doi:10.1519/JSC.0b013e3181b62c0a
Something that is new to the exercise scene is whole body vibration plates. These plates are coined the newest and greatest addition to a training routine and claim to work on multiple systems, from muscle fatigue, central nervous system and strengthening specific muscle patterns. Vibration plates can be effectively used in the weight room to overload the individual’s current routine.
I found an interesting article on the effects of vibration on proprioception and overloading components at the lumbosacral region. Vibration systems evolved from engineers to use in space to assist astronauts with preventing bone density loss or bony density changes during flight adventures. It now, has slowly, found its way into exercise rooms (Fontana, Richardson & Stanton, 2005). These vibration plates are now marketed by multiple companies around the country, but will there be any benefit to a healthy individual? Vibration plate was also referenced in chapter one of our current reading material for this class.
The subjects in the study were divided into two groups, one group used a whole vibration plate and the other group was without. All subjects had sensors placed on the right anterior iliac spine and were monitored by a 3-D Fastrak system. This system could determine pelvic movement both anteriorly and posteriorly. The subjects were asked to reposition the pelvis in one of the two directions while in a static upright stance, while standing on the vibration plate, and they were monitored in how accurate each of them were at repositioning the pelvis into an anterior tilt. To get a more accurate measure of proprioception everyone was blindfolded to eliminate visual senses. The outcomes were very favorable for the use of vibration plates.
According to Fontana et al., the use of a whole-body vibration plate for five minute bouts showed marked improvement on lumbosacral proprioception. Not only did the controlled group improve at the repositioning test, the non-controlled group showed a slight decline in positioning. This proved to be important because this could explain why vibration plates would have positive effects on patients with chronic low back pain (2005). Some of the reasons for chronic low back pain in patients is limited awareness of proprioception at the lumbar-sacral region.
There will be more studies to come on the use of whole body vibration plates. I know that Craig Hospital, in Denver, Colorado, uses them often with their spinal cord injury patients. Studies included muscle fatigue in geriatric patients, vision impaired clients and their effects on tendon structures. I currently use it as an additional way to overload my athletes, by having them perform some of their current exercises on the plate or demonstrate current specific movement patterns on the plate, like baseball/softball swing.
Reference
Fontana, T., Richardson, C., & Stanton, W. (2005). The effect of weight bearing exercise with low frequency, whole body vibration on lumbosacral proprioception: a pilot study on normal subjects. Australian Journal Of Physiotherapy, 51(4), 259-263 5p.
One last comment about the Vertimax, it is a very useful tool. I have one in my gym and have used it for nearly four years and love the versatility. However, when I first got it, I fell for the trap of using it for everything, including some of those crazy exercises that Dr. Rhea discussed in week 5. I was finding myself loading it on an athletes’ bat trying to improve bat power and speed, but after watching film I noticed the individual’s swing changed, so the transfer was not as beneficial as first expected. Therefore, after looking up research and discussing with the company about its available research, I discovered it was best used for less complex movements, movements that were more linear. Now, I mainly use the Vertimax for lower body power and speed movements. I have followed Dr. Rhea’s studies for the last three years, but I still explore ways of using it and have stumbled on a few variations, I use it quite a bit with MMA fighters for hand speed and use it to reinforce hip positon while deadlifting.
It is no secret that resistance training would increase an athlete’s lower body power, but would the Vertimax apparatus be comparable or better, would it show greater results. According to, Rhea, Peterson, Oliverson, Ayllon and Potenziano they looked at two groups, with one that included Vertimax training over a 12-week time frame. Each group participated in similar training programs with one doing additional Vertimax jumps which included quarter jumps, split jumps and half jumps (2008). The results were positive for both groups, however, significantly greater improvements were noticed with the Vertimax group.
Lower body power increases with Vertimax training, “the increase in power in the Vertimax group represented a moderate effect size of .54 and was found to be statistically different from pretest power. Improvement in power following training was found to differ between groups in favor of the Vertimax group” (Rhea et al., 2008, p. 738). This is information that can be helpful for strength coaches or personal trainers that have access to a Vertimax, and it gives coaches other options to use for training athletes. It can also be used in conjunction with weight training exercises and ways to vary up routines. Vertimax training can be very useful, especially when the focus is improving lower body power. It is also important to mention that the Vertimax may be a safer option when comparing with other resisted jump training alternatives.
Reference
Rhea, M., Peterson, M., Oliverson, J., Ayllón, F., & Potenziano, B. (2008). An examination of training on the VertiMax resisted jumping device for improvements in lower body power in highly trained college athletes. Journal Of Strength & Conditioning Research (Lippincott Williams & Wilkins), 22 (3), 735-740.