Research

The Impact of the Laser Gym® Device on Limits of Stability, Functional Mobility, Standing Balance, and Gait of Older Females

John Ward, DC, MA, MS

 

Kimary Farrar, D.C., M.S.

 

Amir Pourmoghaddam, PhD

 

Stefan Kreuzer, M.D.

 

Alham Samani, DC

 

Carol Green

 

author email    corresponding author email   

Topics in Integrative Health Care 2013, Vol. 4(4)   ID: 4.4003



Published on
December 31, 2013
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Abstract

Background: The Laser Gym® device is a product that is designed to have participants engage in hip-related exercises to improve hip flexibility and strength.

Purpose: This study was designed to determine the impact training with the Laser Gym® device had on limits of stability, functional mobility, standing balance, and gait of older females.

Methods: Fifty healthy females over the age of 60 engaged in a baseline Functional Reach Test (FRT), Timed Up and Go (TUG) test, measurement of single and double leg stance test, and a 90-second walking kinematic analysis. Following this, participants were divided into the two following groups: 1) Laser Gym® training group for three weeks at nine 15-min total training sessions or 2) no training control group. All participants then underwent similar post-intervention balance and gait coordination measurements. Pre- versus post-intervention data were analyzed by a statistician blinded to group assignment. Within-groups data were analyzed with a paired samples t-test.

Results: After using the Laser Gym® device for 3 weeks participants were able to reach 1.5 inches farther during the FRT than they could at baseline (p= 0.000).

Conclusions: Preliminarily the results suggest that the action of the pelvic exercises performed using the Laser Gym® device may marginally improve limits of stability of older women. The implications of repeated training on the Laser Gym® device compared to other fall prevention training programs on fall incidence are unclear.

Introduction

Osteoporosis affects 55% of the population over 50 years of age in the United States.1 If a person is osteoporotic he or she is at an increased risk of suffering from a fracture after a fall. The prevalence rates of falls among the elderly are high.2  Elderly who have fallen often fracture bones and have increased rates of morbidity and loss of functional independence as a result of their fall.3-5  Falls are the sixth leading cause of death among the elderly.6

Balance is derived from five systems: vestibular function, visual cues, proprioception, muscle control, and cognitive function.7-10  Studies have shown that regular balance training performed by elderly women with osteoporosis can improve functional balance and reduce the risk of falls.11-12  The exact exercises that would be optimal for fall prevention are debated.11,13  Some studies have demonstrated that biofeedback can be a helpful training tool to improving balance in the elderly, to include a Wii-based system, but further clarity as to the optimal form of anti-fall training should be pursued.14-16

The Laser Gym company was founded in 2010.17 The Core Laser® and Pro Target® are a unique therapy aid designed to improve muscle strength and core balance through laser-guided biofeedback pelvic training exercises.  This is performed by having participants wear a belt with a red laser pointing anteriorly.  They then utilize their hip-related muscles to move the laser and follow one of six patterns on a poster as closely as they can (e.g., to follow a circular path with their laser). Theoretically, by having an older person repeatedly use this product to train their hip-related muscles and proprioceptors, they may to some degree improve their balance and reduce their chance of falls.18,19
 
There are many ways that balance and coordination can be tested.  The Functional Reach Test (FRT) is an effective test of limits of stability through measurement of dynamic balance.20-23 The Timed Up and Go (TUG) test is a measure of functional mobility.24-25 Standing static balance can be measured with single and double leg stance tests on or off force plates.26-30 Lastly, gait biomechanics can be measured using motion analysis systems like the Vicon® imaging system (Denver, CO, USA).31 

Elderly females often suffer from osteoporosis and have diminished balance.  Due to these issues their chance of falling and sustaining a fracture is increased.  Falling can result in significant economic cost to the patient and increased morbidity.  An effective countermeasure for this would likely impact the health of millions. The extent by which the Laser Gym® device could positively impact the limits of stability, functional mobility, static standing balance, and gait of older women at risk for falls has not been explored.  The purpose of this study was to determine if regular training for 3 weeks with the Laser Gym® device would improve any of these variables in older females.  

Methods

This study was reviewed and approved by the Institutional Review Board for human subjects at the sponsoring university in accordance with the Declaration of Helsinki.  All subjects were provided a written and oral explanation of the study procedures prior to participation.

Study Design and Setting



This was a controlled study of the impact that the Laser Gym® device had on the limits of stability, functional mobility, static standing balance, and gait of older women.  Our specific aims were to determine if the Laser Gym® device improved these balance and coordination-related variables using an older female study group.

As shown in Figure 1, fifty older females were involved in this study. Participants underwent baseline testing of their limits of stability, functional mobility, single and double leg stance test time, and gait.  Participants then self-selected if they would be in the intervention or control group based on their schedule availability.  Study participants in the experimental group underwent 3 weeks of training with the Laser Gym® device for a total of nine 15-minute training sessions.  Participants in the control group did not undergo any training.  After this participants in both groups engaged in a post-test of baseline balance and coordination-related variables.

Fig 1. Experimental design. 



Participants



Asymptomatic female volunteers over the age of 60 were recruited with online advertisements and via word-of-mouth.  All study applicants provided an informed written consent on college-approved documents.  They were then screened against inclusion and exclusion criteria.  Fifty apparently healthy individuals who met the inclusion/exclusion criteria participated in this study (Table 1).  Five participants were excluded from this study due to violating the exclusionary criteria.   Following completion of the study, participants were given gift cards to a local store to compensate for their time.

Table 1. Baseline study participant attributes.

 
Laser Gym training
no training group
 
group
(control group)
 
(experimental group)
 
Participant number (n)
25
25
 
 
 
Age (y)
69.7 + 7.2
72.8 + 7.7
 
 
 
Body Mass (kg)
63.9 + 12.3
65.5 + 17.0
 
 
 
Height (m)
1.62 + 0.07
1.60 + 0.05
 
 
 
Body Mass Index  (kg/m2)
24.4 + 3.8
25.8 + 7.0
Data listed as mean + SD.
 
 



Inclusion/exclusion criteria



Inclusion criteria were: 1) between the ages of 60-90 years old and 2) signed the informed consent form.  Study participants with any of the following were excluded from the study: 1) legally blind, 2) severe auditory deficiency, 3) vestibular disease, 4) lack of the ability to walk 6 feet unassisted, 5) avascular hip necrosis, 6) Parkinson’s disease or similar degenerative musculoskeletal disorders, 7) tremors, 8) lower limb joint replacements, 9) severe osteoarthritis, 10) peripheral ischemic symptoms, or 11) peripheral neuropathy/myopathy.

Functional Reach Testing



This involved participants standing adjacent to a wall with a tape measure attached to it.  They then were instructed to reach as far as they could, without falling over, using a combination of ankle and hip balance strategies.  A spotter was present next to the participants to catch them if they lost their balance. 

Timed Up and Go Test



For this test participants rose from a chair, walked 3 m, returned back to their chair, and then sat down as quickly as they could.  Similarly participants were informed that a spotter would follow them as they walked as quickly as they could during this test to reduce any anxiety. 

Single and Double Leg Stance Test



During this phase of testing participants stood on top of a Bertec 4060-NC force plate (Bertec Corp., Columbus, OH, USA) as illustrated in figure 2.  The force plate data were recorded directly through Vicon®.  Participants were initially instructed that they would be standing on one foot as long as they could for up to 30 seconds.  A spotter was available and there were safety rails put up on both sides of the participant to reduce any anxiety about fall risk.  The right lower limb was tested first, and then the left lower limb.  Afterwards participants were instructed to place their lower limbs together and close their eyes to repeat the test, with both lower limbs planted on the ground.  Force plate  directly exported from the Vicon® imaging system and analyzed with Matlab® for the duration the person was able to stand before losing their balance during each of the three conditions.

Fig 2. Illustration of the single and double leg stance test procedures: a) One-legged testing eyes-open for the left extremity, b) One-legged testing eyes-open for the right extremity, and c) Two-leg testing eyes-closed.  The participant held each position as long as they could (for up to 30 seconds).



Baseline Preparation and Kinematic Recording



Participants were all given a verbal description of the procedures prior to testing to reduce anxiety during the test.  Upon arrival to the session they changed into non-reflective clothing and shoes.  Shoes were chosen as opposed to having participants walk barefoot to most closely emulate a real-world scenario.  Next, trained research assistants placed eighteen 19 mm (MoCap, solutions, Huntington Beach, CA, USA) reflective markers on the participant’s lower body using surgical tape.  Reflective markers were placed on the following anatomic landmarks during this study bilaterally: ASIS, posterior inferior iliac spine, greater trochanter of the femur, lateral epicondyle of the femur, tibial tuberosity, lateral malleolus, posterior calcaneus, top of the fifth metatarsal head, and top of the first metatarsal head (Fig. 3), with a marker set and model as described by Robertson et al.32

Fig 3. Illustration of a study participant and a sample computer model based on reflective marker data extraction using the Vicon® imaging system.  Only the left side of the participant is marked in this diagram to avoid image clutter.



Prior to the participant arriving at the lab each day the Vicon® system was calibrated as suggested by the manufacturer.  Once the participant was dressed properly and all of the reflective markers were in place they stood on top of the 400 Pro series Keys® treadmill (Keys Fitness Products, Inc., Dallas, TX, USA) for their baseline 10-second calibration model generation.  Next the participant was instructed that they would be walking as they normally would at a velocity of 1.5 mph.  A research assistant started the treadmill at the same time as another researcher began recording data with the Vicon® system.  The lab’s Vicon® MX system consisted of 8 infrared Bonita 0.3 megapixel cameras.  Kinematic data were recorded at 100 Hz.  The displacement of the 18 reflective markers over time was recorded.  At the conclusion of 100 seconds the researcher operating the Vicon® computer system stopped the recording and then the treadmill was stopped.  The study participant was not given any indication of when the treadmill would be stopped prior to the examiner finishing his computer data recording.  Immediately after the 100 second recording was made the initial 10 seconds of data were clipped from the data to remove any initial steps as the participant became acclimated to the treadmill upon beginning the test.  Following the baseline 90 seconds of data collection the participant then carefully stepped off of the treadmill and their testing session was complete for that given day.

Laser Gym® training protocol



The intervention phase of the study was performed by having participants engage in hip exercises according to the Laser Gym® manual for 15 minutes.  This involved participants using their hips to move a front-facing red laser on a belt through several line, circle, and figure-eight motions (Figure 4).  Participants engaged in all six basic hip training exercises at 5’ from the Laser Gym® poster.  A research assistant supervised all motions and instructed the participant repeatedly to try their best to stay on the colored lines of the pattern they were trying to complete (e.g., using their laser to follow the path of a large blue circle on the poster).  Midway through each training session participants were given a 30 second rest period to recover.  Participants in the control group did not receive any training on the Laser Gym® device.

Fig 4. Illustration of two participants using the Laser Gym®.  Research assistants were standing behind them instructing them as to which pattern to follow next and encouraging them to stay as close to the correct laser path as possible.



Kinematic Gait Post-data Processing



The gait data were processed using a customized Matlab® script (Mathworks, USA R2007a). The kinematic data were analyzed to calculate characteristics of movement for each participant. In the current study we investigated the changes in the functional active range of motion of the hip angle, knee angle, and ankle angle as a result of the intervention. In addition, the double support time, percent double support time (duration both feet were on the ground in relation to the gait cycle), stance time, percent stance time (duration one foot was on the ground in relation to the gait cycle), step length, and stride length were calculated bilaterally.

Approximate Entropy, a measure of gait variability, was additionally determined for each joint.  In healthy individuals there is a certain amount of acceptable variability that represents a normal (healthy) gait pattern. However, highly variable gait patterns are typically indicative of some type of pathology or loss of coordination,33 which may render a person at risk for falling.34  Gait variability has been identified by the application of a mathematical technique called approximate entropy (ApnEn) that may reveal small changes in the gait pattern.33,35-36 Values near “0” represent a stable gait, while values near “2” represent a very unstable gait.

Statistical Analysis



To analyze the calculated data we have utilized a paired samples t-test to compare pre to post-data.  A Bonferroni adjustment was used in relation to our 29 dependent variables, thus our level of significance was set at p<0.002. Study data are illustrated in Tables 1-3. The data were analyzed using SPSS 20.0 (SPSS Inc., Chicago, IL, USA).

Table 2. Comparison of the Functional Reach Test, Timed Up and Go Test, and Single and Double leg stance test. FRT = Functional Reach Test in inches, TUG = Timed Up and Go test in seconds, R Leg = Right leg only balance test with eyes open in seconds, L Leg = Left leg only balance test with eyes open in seconds, Both Leg = Both leg balance test with eyes closed in seconds.
 
 
Experimental group
Pre
 
Post
 
t-test
Mean
SD
Mean
SD
Mean Diff
p
FRT
10.7
2.4
12.2
2.4
-1.5
*0.000
TUG
6.8
1.0
6.3
0.9
0.5
0.004
R Leg
19.6
12.4
21.4
11.1
-1.8
0.408
L Leg
17.1
13.0
17.3
11.9
-0.2
0.845
Both Leg
30
0.0
30
0.0
0.0
1.000
Control group
Pre
 
Post
 
t-test
Mean
SD
Mean
SD
Mean Diff
P
FRT
10.2
2.0
10.5
2.0
-0.3
0.393
TUG
7.3
1.5
7.3
1.4
0.0
0.430
R Leg
15.4
12.5
13.1
12.9
2.3
0.238
L Leg
14.0
12.4
13.9
12.0
0.1
0.960
Both Leg
30
0.0
30
0.0
0.0
1.000



Table 3a. Gait attribute data for the Laser Gym® training group. R= right; L= left. HpROM = hip functional range of motion in degrees; KnROM = knee functional range of motion in degrees; AnROM= ankle functional range of motion in degrees; DSTSec= double support time in seconds; %DS= double support percentage of gait cycle; STSec= stance time in seconds; %ST= stance percentage of gait cycle; StepLen= step length in millimeters (25.4 mm= 1 inch); StriLen= stride length in millimeters; HpApnEn= hip approximate entropy; KnApnEn= knee approximate entropy; AnApnEn= ankle approximate entropy.
 
 
 
Pre
 
Post
 
  t-test
Mean
SD
Mean
SD
Mean Diff
p
RHpROM
49.2
21.4
44.0
8.4
5.2
0.172
RKnROM
61.7
18.9
59.1
14.8
2.6
0.400
RAnROM
29.8
7.0
32.7
7.7
-2.9
0.005
LHpROM
46.6
9.8
45.8
10.6
0.8
0.608
LKnROM
61.2
10.3
59.1
11.1
2.1
0.205
LAnROM
29.9
11.2
31.9
10.2
-2.0
0.019
LDSTSec
0.25
0.07
0.26
0.07
-0.01
0.143
RDSTSec
0.24
0.06
0.25
0.08
-0.01
0.153
L%DS
20.4
2.6
20.3
2.0
0.1
0.578
R%DS
19.0
4.4
18.7
4.3
0.3
0.307
LSTSec
0.91
0.25
0.95
0.23
-0.04
0.100
RSTSec
0.90
0.21
0.92
0.19
-0.02
0.125
L%ST
68.9
6.2
68.7
5.9
0.2
0.157
R%ST
69.6
4.8
69.3
4.3
0.3
0.291
LStepLen
312.4
85.4
335.9
72.4
-23.5
0.045
RStepLen
302.6
85.3
320.8
88.1
-18.2
0.039
LStriLen
788.5
220.7
856.3
180.5
-67.8
0.011
RStriLen
807.6
225.9
875.9
192.5
-68.3
0.009
LHpApnEn
0.28
0.08
0.30
0.08
-0.02
0.368
LKnApnEn
0.40
0.07
0.41
0.07
-0.01
0.794
LAnApnEn
0.67
0.16
0.64
0.13
0.03
0.201
RHpApnEn
0.35
0.13
0.32
0.10
0.03
0.351
RKnApnEn
0.43
0.08
0.44
0.09
-0.01
0.848
RAnApnEn
0.67
0.14
0.64
0.11
0.03
0.138
 


Table 3b. Gait attribute data for the control group. R= right; L= left.  HpROM = hip functional range of motion in degrees; KnROM = knee functional range of motion in degrees; AnROM= ankle functional range of motion in degrees; DSTSec= double support time in seconds; %DS= double support percentage of gait cycle; STSec=  stance time in seconds; %ST= stance percentage of gait cycle; StepLen= step length in millimeters (25.4 mm= 1 inch); StriLen= stride length in millimeters; HpApnEn= hip approximate entropy; KnApnEn= knee approximate entropy; AnApnEn= ankle approximate entropy. 
 
 
 
 
Pre
 
Post

 
  t-test
Mean
SD
Mean
SD
Mean Diff
p
RHpROM
42.7
7.2
41.2
6.8
1.5
0.281
RKnROM
55.2
5.6
55.5
5.2
-0.3
0.765
RAnROM
34.4
10.1
35.4
10.3
-1.0
0.395
LHpROM
45.0
8.5
42.6
8.3
2.4
0.116
LKnROM
59.1
13.9
55.0
11.0
4.1
0.066
LAnROM
33.6
11.7
35.6
12.0
-2.0
0.172
LDSTSec
0.27
0.05
0.28
0.06
-0.01
0.057
RDSTSec
0.26
0.04
0.28
0.05
-0.02
0.083
L%DS
20.2
1.6
20.3
1.7
-0.1
0.764
R%DS
20.0
1.9
20.3
1.6
-0.3
0.182
LSTSec
0.94
0.14
0.97
0.16
-0.03
0.118
RSTSec
0.94
0.14
0.97
0.16
-0.03
0.097
L%ST
70.4
3.2
70.3
2.8
0.1
0.750
R%ST
70.8
3.4
70.8
3.1
0.0
0.825
LStepLen
343.7
106.0
359.0
107.0
-15.3
0.029
RStepLen
339.6
94.0
346.3
100.2
-6.7
0.263
LStriLen
904.6
197.1
912.8
242.8
-8.2
0.787
RStriLen
921.7
206.5
927.5
252.5
-5.8
0.866
LHpApnEn
0.28
0.12
0.25
0.06
0.03
0.205
LKnApnEn
0.34
0.09
0.34
0.06
0.0
0.656
LAnApnEn
0.62
0.14
0.57
0.17
0.05
*0.000
RHpApnEn
0.30
0.07
0.27
0.08
0.03
0.166
RKnApnEn
0.37
0.04
0.34
0.07
0.03
0.028
RAnApnEn
0.57
0.15
0.56
0.14
0.01
0.171
 


Results

Participants training on the Laser Gym® device were able to reach 1.5 inches farther than they could at baseline (p=0.000).  Additionally, the control group demonstrated a statistically significant decrease in the approximate entropy of their left ankle (p=0.000).  This change suggests that their ankle motion became more stable.  We are unclear as to why this change occurred and believe it is likely due to random variance in gait patterns.  No other study dependent variables were affected by the study treatment.

Discussion

Data from this study preliminarily suggest that the hip related exercises employed by the Laser Gym® protocol can marginally improve limits of stability amongst older females.  Unfortunately, other balance/coordination attributes to include functional mobility, static standing balance, and gait did not reach statistical significance.

Studies have demonstrated that the degree of spinal mobility and muscle strength of older females with osteoporosis has a direct correlation with their quality of life because it impacts their fall risk.37-38  The impact the Laser Gym® device has in comparison to other anti-fall prevention programs at impacting muscle strength and range of motion is not clearly known.  General exercise, Tai Chi, and vitamin D supplementation have all been shown to improve balance and coordination amongst the elderly.39-42 Some newer technologies, like the Balance Rehabilitation Unit virtual reality system have recently been shown to also be effective methods of improving balance, increasing confidence, and preventing falls in the elderly.43

Limitations

Participants in our study only trained for three weeks on the Laser Gym® device.  It is plausible that a longer duration of training may have positively impacted balance and coordination further.  Studies involving strength gains of novice individuals engaged in exercise suggest the first 6-8 weeks of strength gains are primarily due to neural reorganization.44

Our participants were reasonably healthy.  The impact the Laser Gym® device would have on patients with various disease states like stroke, Meniere’s disease, and other conditions that likely would impair balance and coordination remains unknown.  An additional limitation was lack of randomization, which may have resulted in bias.

The balance and coordination tests we chose each had limits.  For example, the Timed Up and Go test has been criticized because it does not require participants to walk distance that would be functional in most settings (e.g., walking around a grocery store).45   Some have found the Timed Up and Go test to not be a clear predictor of fall risk in the elderly. 46-51 Likewise the FRT test has been criticized because rotation of the trunk and shoulder blades may impact the results.21

Conclusions

There is minimal research into how exercise may impact balance and coordination amongst elderly females.  The focus of this experiment was to determine if the Laser Gym® device could positively impact these variables.  The findings of this study suggest that the Laser Gym® device may marginally increase limits of stability in older females.  The implications this small improvement may have on older females at risk for falls is unclear.

Funding sources and potential conflicts of interest

This study was supported by a grant from the Laser Gym® company, which was used solely for compensating study participants for their time.
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