CASE STUDY- The Effect of a Half Squat on Reducing Low Back and Knee Pain During the Club Volleyball Season, and it’s Effect on Vertical Jump:

***Scott Moody

Introduction

Due to the demands of the sport, the intensity of the practices and the height and anatomical make up of outside hitters and middle hitters, the knees and back seem to take a beating. The sport demands quick lateral movements, followed by maximal vertical effort jumps without the full use of an arm swing (close proximity to the net), and without much time to perform a counter movement to properly position the body (speed and timing of the block). This combination produces technically poor mechanics for achieving maximal height and causes undo stress on the knees and back.

Over the past six years of seeing hundreds of volleyball players we have great success improving vertical under these conditions, but the knee problems still persisted. We have tried lighter weight, low volume, and various forms of squatting but under these conditions the vertical over time would start to drop (sometimes as significantly as 3-4 inches).

This study was designed to see if we could still get vertical increases while significantly reducing the occurrence of low back pain and knee pain…

Methods

Experimental Approach

Pilot work found that subjects who had experienced less pain when they control the depth of the squat. This study was designed to replace the full depth back squat with the half squat and supplement swiss ball hamstring curls and full depth lunges to make up for the decreased glute and hamstring activation. We also will add resisted movements on a Woodway Force © treadmill to supplement the functional range of motion during hip extension at greater speeds than typical squatting.

Subjects

The study was comprised of 12 high school volleyball middles and outside hitters with an average age of 16.72 (+/- 1.49 years), an average height of 5 ft 9 inches (+/- 3 inches), and average weight of 139 lbs (+/- 52 lbs). All subjects have had previous training experience in our program of at least 9 months (some have been here for over 3 years). All have a good understanding of training, squat technique, volleyball skill, etc. They are all varsity level players that will play in college.

Testing and Measurement

Vertical Jump (SVJ):

The vertical jump test was used due to its widely accepted intra-subject reliability and the fact that it does not require high motor ability and can easily performed by children. After a 45 minute warm up consisting of dynamic flexibility, stability, and balance and agility based movements, each subject was given 4 attempts in a jump and reach (counter movement jump - with no step) using a Vertek © device. The best jump was recorded.

Squat:

We worked on technique for 6 sessions (approximately 3 weeks) before implementing the progressive overload strategy for improving squat strength. This time frame was enough to adequately assess the knee and back pain situation, while getting the group to the same level of technical efficiency in all of these exercises. We then went off a progressive overload system with reps of 15, 12, 10 and 8 for 2 cycles (8 weeks). With this protocol we would have 3 weeks with an increase in weight with the 4 th week being a back off.

Knee and Back Pain (KBP):

Each subject was asked to rate the level of knee and back pain on a scale of 1-3 pre and post study. A score of 3 meant the pain level was so high that they were in pain while sitting, standing, walking (constant pain). A score of 2 meant that the subject was in pain when walking up stairs, exercising and practicing (pain during strenuous activity). A score of 1 would mean that there was pain only following strenuous activity (practice, games, or weightlifting) but not during. And finally a score of 0 would mean that there was no pain in the knees or back. Obviously, some of the pain would be from high volume tournaments, drills at practice, etc. so we did expect some fluctuating scores. What we were looking for is a general trend towards less knee pain or at least no increase.

Testing Procedure:

Each subject was tested in each of these areas on the first week of the Winter Training Session ( 11-14-05 to 2-24-06) with a focus on educating them proper technique, and strategy to ensure a good test. We let each subject take 2 to 4 attempts at each vertical to try and achieve their best. Then each subject was tested again 3 weeks later to assess improvements due to learning curve and to make the final assessment pain in the knees and back.

Training Programs

The training program was broken into 6, 15 minute blocks (1-Warm Up, 2-Sprint Drills/Rhythm/Stability, 3- Athletic Movement/Low Level Plyos/Speed/Agility, 4-Power Production, 5-Strength Training, and finally 6-Conditioning and Core Work). The group then performed the plyos, rhythm and speed drills on the Woodway Force © treadmill. All other aspects of the program remained the same.

• Warm up: primarily composed of some basic reciprocal inhibition (muscle activation) and dynamic flexibility work
• Stability: The group did the same ground based balance hip and hamstring based stability drills, but did not perform the sprint drills, split squats or the box jumping drills. Instead they perform the sprint drills, skipping drills and form runs on the Woodway Force © Treadmill. See: The Effects Resisted Sprint Training on Speed, Agility and Power Production in Young Athletes research study for more information.
• Plyo/speed/agility : rapid and short response (basic) plyometric drills, rhythm and coordination footwork, single-cut lateral agility drills, and sprint work
• Power : basic hip extension (pull based) lifting with light weight for reps of 6-10 at 40-60% of 1RM
• Strength : basic upper and lower body exercises (squat, lunge, push up, pull up, light db combos and complexes)
• Conditioning and Core Work : medicine ball core circuits combined with movement drills to get the heart rate up over a 10 min period

Results

Subjects showed similar increases in vertical as other training groups that were squatting to parallel. The steady improvement of verticals continued throughout the entire 8 week strength phase and then continued into the power phase (Phase III) where a 30% of back squat load was added to jump squats, and bands were added to the Dynamic Squat Day (Day 2) each week. The verticals leveled off in the speed phase (Phase IV) where less emphasis was placed on vertical and more emphasis was places on footwork and speed of the movement. As you can see during this phase squat maxes (training weights projected as maxes) decreased, but speed continued to increase.

The level of back pain for those individuals who ranked their back pain as a 2 or greater had minor decreases during the study (from a 2 to a 1.87 and from a 3 to a 2.1), but no athlete had an increase. In past years with the same type of client there seemed to be an increase in the level of back pain as we went through a strength phase with heavier back squats and jump squats although we don’t have the data to prove this at this time. Some of the soreness in the lower back seemed to increase on days (usually Monday’s) following tournaments or heavy conditioning practices the night before.

The level of knee pain for those individuals who ranked their knee pain as a 2 or greater had major decreases during the study (from a 2 to a 0.9 and from a 3 to a 1.4) and again no athlete had an increase in knee pain over the course of this study. The fact that there was still a reduced amount of pain in the knees even as we went into Phase III (Power and Speed), seemed to greatly impact their agility and aggressiveness in approach verticals.

The athletes in this study increased their verticals on average 1.4 inches during this study. When compared to other athletes of their same age (16.7 yrs old – junior’s in high school) displayed in figure 7, you can see that this is still way above the average .27 inches shown in the study. So in our opinion, although there still could have been a greater improvement in vertical jump, we feel that the 1.4 in increase was impressive. When you take into consideration most of the girls in this study have stopped growing and have reached maturity, and add to that the fact that they have trained for 2-3 years in a strength training program, massive gains are hard to come by.

Discussion

The study was a success in the fact that it seemed to reduce pain in the knees and back while still noticing increases in agility and power (shuttle and approach vertical). However, a deeper look into this study might bring fourth the question of how much other factors outside the realm of this study affected the vertical and shuttle as well as knee and back pain. There will always be the case of increased flexibility, mobility and core strength with the athletes could have been responsible for the decreased pain. There could also be the argument that the natural development of the athlete combined with the emphasis on technique and positioning could have taken stress off the knees and therefore improved performance while reducing pain.

There will also be the case made that practices (which seemed to be more of a factor than the actual workouts) could have played a big part in the increases in pain on certain days. We asked the athletes on a daily basis how they felt, to what they attributed to the pain, and whether or not they felt like they were improving. Their responses reflected the graphs, in that they always felt like it was getting better or that they were getting better at controlling the things that they know will cause them pain.

But regardless the study was successful due to the fact that performances increased and pain was decreased over the course of this study. Arguments are always going to question the methods, and the fact that there was not a control group in this study, and that may be something we need to research in a more sterile environment in the future, but due to the ever changing environment that these athletes train and practice in a sterile study was just not practical for this group at this time.

Practical Applications

This study has sparked the question, “What types of drills are going on at practice that are causing back and knee pain?” In my opinion, the lack of a strategic warm up protocol that is designed to target activate, stabilize, and increase blood flow to the areas of concern, before starting the “impact” type drills (jumping/landing, skipping, cutting, hitting, etc.).

Maybe most importantly, after practice, I see a need for a proper cool down. Some of the athletes will finish practice, jump in their car, drive 20 minutes home, and then sit in a chair and do homework for a few hours. This kills the recovery process, and will lead to unnecessary soreness and pain the next day.

I think that the quarter/half squat protocol did exactly what it was designed to do. If we have athletes at CAP that start to complain of lower back pain or knee pain, we will modify their workouts with the restricted range of the squat, and discuss training protocols with the club or high school coach. In the future we will also begin to look at muscle activation techniques, reciprocal inhibition and core strengthening protocols and the effects that they have on the knee and lower back pain of high school athletes.

References

1. Eston, Roger and Reilly, Thomas. Kiinanthropometry and Exercise Physiology Laboratory Manual – Tests, Procedures and Data – Second Edition Volume 1

Routledge ( UK), 2001.