1. Summary
2. What is the Multiple Single-Leg Hop-Stabilization Test (MSLHST)?
3. What changed from the Bass to the Multiple Single-Leg Hop-Stabilization Test?
4. How do you conduct and score the Multiple Single-Leg Hop-Stabilization Test?
5. Is the Multiple Single-Leg Hop-Stabilization Test valid and reliable?
6. Conclusion
7. References
8. About the Author

Summary

The Multiple Single-Leg Hop-Stabilization Test (MSLHST) is a dynamic and static balance assessment tool designed for the sporting population and based on the original Bass Test [3] and its modified version [8] for assessing balance.

The MSLHST is a clinical method used to examine the balance capabilities of an athlete, one leg at a time. The subject performs dynamic forward and diagonal one-legged jumps while statically maintaining landing positions [4].

What is the Multiple Single-Leg Hop-Stabilization Test?

The original Bass Balance Test was first introduced over 80 years ago [3], and later modified for improved application [8]. Traditionally, a balance test was performed in neurological patients with the task of maintaining a certain position as long as possible [6]. The Bass Balance Test laid the groundwork by implementing a more challenging task into balance testing. Since then, it has been adapted throughout the years, and recently optimised by Riemann et al. (1999) who renamed the test “The Multiple Single-Leg Hop-Stabilization Test (MSLHST)” [4].

Healthy balance is maintained by the interactions of multisensory body systems that are orchestrated by the brain and spinal cord [4, 9]. Proprioceptive, as well as visual and vestibular information, is processed and results in actions of the musculoskeletal system [9]. Testing balance in a standardised way, while offering enough challenge to prevent ‘ceiling effects’, is a common struggle in fitness testing and has resulted in no available gold standard to date [6].

Having said that, this modernised version is a more reliable clinical tool used to assess balance in an active sporting population [6, 8].

What changed from the Bass test to the Multiple Single-Leg Hop-Stabilization Test?

The MSLHST [4, 8, 9] was adapted from the Bass test to ensure an equal challenge for all participants. Improving on the Modified Bass Balance Test, the MSLHST controls for upper-body and arm sway, whilst also normalising the error scoring to achieve more reliable and valuable clinical test results.

One of the major problems with the design of the Modified Bass Balance Test is the inconsistencies regarding the error scoring and irregular challenging of the test subject. Since the marker distances remain the same for all participants, a taller person may have little trouble performing the jump, while a shorter athlete may struggle considerably [4].

The optimisation of this test was achieved by changing the marker distances according to the subject’s standing height. The longest jumping distance, as marked with a blue arrow in Figure 1, is set at 45% of the subject’s body height measured with sports shoes. The sideways and forward jumps were set to be of equal distance. This results in an easy adaption of the Pythagorean Theorem to calculate all marker distances. For a person of 170 cm in height, the longest distance (between markers 2 and 3 and markers 7 and 8) becomes 76.5 cm. The straight movement distances forward and sideways become ~54 cm long:

The introduction of the Balance Error Scoring System (BESS) into the test, makes it more reliable and comparable to adjacent scientific work. BESS values show great correlation with the sway of the centre of gravity, as recorded by a more expensive force plate in a laboratory setting [11].

How do you conduct and score the Multiple Single-Leg Hop-Stabilization Test?

Always perform fitness testing on a dependable surface that is not affected by wet or slippery conditions and is protected from varying weather types. Changing the testing environment will weaken the reliability of repeated tests and could potentially result in worthless data.

Required Equipment

• Consistent testing facility (e.g. gym or laboratory)
• Measuring tape
• Marking tape/sports tape
• Metronome (loud audio cues)
• Performance Recording Sheet

Test Configuration
The test is performed with the subject standing on one foot on the start marker looking straight ahead. Both hands are to be rested on the ipsilateral iliac crests for the entire duration of the test. A metronome gives an audio cue every second to ease time orientation for the subject.

When instructed to jump to the following marker (marker #1), the subject may take a brief look at the goal marker, jump, and land covering the marker with the foot entirely. Eyes should be looking straight ahead while maintaining the position for five seconds before advancing. The five-second stance is counted aloud by the tester to further facilitate the time orientation of the subject. All markers are to be jumped to in the numbered order as depicted in Figure 1.

Foot dominance (i.e. preferred foot to kick a ball) is to be determined before conducting the test and to be noted. However, the order of foot testing would ideally be randomised.

Any observed errors during any of the jumps to a marker are not to interrupt the test or to be commented on in any way. They are simply noted in real-time on the performance sheet in a point fashion as shown in Table 1.

Table 1. Error Scoring System (Adapted from [8])

For the 10 marker jumps, a maximum of 130 error points can be observed. Lower error scores are defined as a better performance and ultimately a higher balance ability.

Is the Multiple Single-Leg Hop-Stabilization Test valid and reliable?

To determine if a test is valid, inter-tester, as well as intra-tester reliability, must be determined. Inter-tester reliability is being calculated by comparing test values of the same subject by at least two different testers. Thus, intra-class correlation coefficients (ICCs) of how “equal” the test results are can be shown.

The strength of the correlation coefficients is commonly interpreted as [1, 5]:

• 0 = zero
• 1 – 0.3 = weak
• 4 – 0.6 = moderate
• 7 – 0.9 = strong
• 0 = perfect

Riemann et al. [4] examined inter-tester validity using repeated-measures analyses of variance (ANOVAs) with three testers who were each blinded against the results of the other testers and performed each test twice. Test repetitions were 48 hours apart [4].

They were able to show very good inter-tester reliability with ICCs ranging from 0.70-0.92. While the landing error scores showed no significant difference between the testers (ICC 0.92 and 0.92), the balance error scores differed significantly between two of the three testers resulting in slightly lower ICCs of 0.70 and 0.74. Still, even the lowest value (0.70) is still in the “strong” correlation category.

Until 2017, the intra-tester reliability of the MSLHST had not been investigated. Sawle et al. [9] conducted their intra-rater reliability study with one investigator in a single session. Their findings show an ICC range between 0.72-0.88 which points towards good to excellent reliability of repeated tests. Other than for Riemann et al. (1999) [4], this study found better reliability scores for balance (ICC 0.88 and 0.87) instead of landing scores (ICC 0.72 and 0.78) [9].

Both studies reflect differences in score reliability between balance and landing scores. As the MSLHST assesses the sum of the two scores, and both the inter-rater and intra-rater ICCs are in clinically acceptable standards, the test can be recommended for inclusion in future clinical trials of recreationally active participants and athletes [4, 9].

A test is only valid if it is reliable and can actually offer information that is relevant to what the test sets out to test – the MSLHST aims to assess an athlete’s balance. Balance and/or proprioceptive exercises are tools for injury prevention and rehabilitation [11]. Knee instability is associated with one-legged jumping performance [13]. Thus, the MSLHST consists of repeated forward and sideways one-legged jumps, and it is considered to challenge the athlete in a way which reflects common forces and manoeuvres that are not only performed in sports [9] but also help determine if a player obtains an injury or not [10]. As a result, the MSLHST is therefore regarded a valid balance assessment tool.

Conclusion

The Multiple Single-Leg Hop-Stabilization Test (MSLHST) is a modernised and valid variant of the Modified Bass Balance Test.

It successfully assesses an athlete’s static and dynamic balance and makes a comparison between the dominant and non-dominant leg possible. It is suitable for use in rehabilitation, in repeated measures during a balance/proprioception training programme, and shows potential for information on the return-to-sport status of the test subject.

The test should be included in future research on recreational and professional athletes as well as on other populations of a similar nature to measure functional balance.

The post Multiple Single-Leg Hop-Stabilization Test appeared first on Science for Sport.

1. Summary
2. Why is measuring balance important?
3. What is the Modified Bass Balance Test?
4. How do you conduct the Modified Bass Balance Test?
5. Is the Modified Bass Balance Test valid and reliable?
6. Conclusion
7. References
8. About the Author

Summary

The original Bass Balance Test is a high-performance balance test that was first presented in 1936 by Dr Ruth Bass [3]. The test has since been modified in 1968 for improved application [4]. Later, in their 1986 book “Practical Measurements for Evaluation in Physical Education”, Johnson and Nelson [5] published the Modified Bass Balance Test as a clinical method for the assessment of functional jump-landing balance performance. Dynamic forward and diagonal movements are coupled with statically maintaining landing positions [4].

Why is measuring balance important?

Balance requires a joint effort from the neuromuscular system and other multi-organ sensory systems (vestibular, visual, and proprioceptive). Balance can be tested both statically and dynamically [1] with no gold standard currently available for the athletic sporting population [6]. Establishing a balance test for this specific population must include dynamic features since all sports require a ‘dynamic’ attribute of balance in some way [6].

The Modified Bass Balance Test used to be the only standardised balance test that incorporates both static and dynamic tasks [4, 5]. Today, balance is often tested on force plates that record the stabilising actions of the foot, but these often remain insensitive to upper-body sway [7].

What is the Modified Bass Balance Test?

As described by Johnson and Leach (1986) [4], the test is performed using both feet in an alternating order to jump to and from tape markers along a course. The distance of the tape markers is fixed and remains the same for every test subject. The tape markers are to be covered entirely with the foot on landing. No additional instructions are given concerning arm and hand placement. No comment on landing and/or technique can be made.

How do you conduct the Modified Bass Balance Test?

All fitness testing should be performed on a dependable surface that is not affected by wet or slippery conditions and is protected from varying weather types. Changes in the testing environment weaken the reliability of repeated tests and result in worthless data.

Required Equipment

• Consistent testing facility (e.g. gym or laboratory)
• Measuring tape
• Marking tape/sports tape
• Metronome (loud audio cues at 60 beats/min)
• Performance Recording Sheet

Test Configuration
The test is performed with the subject standing on the start marker with their right foot and looking straight ahead. A metronome gives an audio cue every second to ease time orientation for the subject. Instructed to jump to the following marker (marker #1), the subject is allowed to take a brief look at the goal marker, jump, and then land on the ball of the left foot covering the marker.

They must keep their eyes looking straight ahead while maintaining the position for a maximum of five seconds before advancing to marker #2. The five-second stance is counted aloud by the tester to further facilitate time orientation of the subject. All markers are to be jumped to with alternating feet in the numbered order. Figure 1 depicts all distances between the markers.

How do you score the Modified Bass Balance Test?

Each successful landing earns the subject five points. Each second the subject holds a steady position, they are rewarded with another one point; meaning a total of 100 points are possible for the entire test. According to this test, higher scores imply better balance.

Landing faults result in the loss of the five landing points. Landing faults include:

• Touching the floor with the non-supporting foot.
• Touching the floor with the heel of the supporting foot.
• Failing to stop on landing.

The foot partially covering the tape mark results in a three-point loss. Failing the landing entirely, no landing points are being rewarded. The test continues with the subject taking the balance position (ball of one foot on the marker). Holding the balance position for five points can then still give full balance points (0 landing points, 5 balance points; for this marker).

Balance errors include:

• Touching the floor with any other body part than the ball of the supporting foot.
• Moving the planted foot while maintaining balance position.
• If the subject loses balance completely, no additional balance points are rewarded. The subject proceeds by leaping to the next assigned marker. Every balance fault results in a loss of one point per second.

Is the Modified Bass Balance Test valid and reliable?

The Modified Bass Balance Test is a sparsely used balance test. Due to insufficient validation, the test is not recommended in scientific practice.

Ambegaonkar et al. (2013) describe the test as having “…acceptable reliability of 0.75” [2] and a validity of 0.46 [1, 8]. However, since the authors did not go any deeper on this, and the original source from Johnson and Leach (1968) is not available in a computerized version, it remains unclear to which kind of reliability is meant, and if the scientific methods used were sufficient to detect appropriate levels of reliability. Furthermore, the authors were unable to show the differences in balance between dancers and active non-dancers [2].

Tsigili (2001) examined the reliability of the Modified Bass Balance Test by comparing it to the current standard test using a stabilometer, with no significant correlation being observed [8]. Also, the authors recorded very high performance values (mean = 91.45) close to the ceiling of 100 points. This could have impacted variability values. The test seems too easy to perform for their population of undergraduate students [8].

The Modified Bass Balance Test records both static and dynamic movement errors. The end score, on the other hand, combines both scores. It is unclear if static and/or dynamic deficiencies get “washed out” or if the score accurately depicts a person’s balance [1].

As the tape marker distances remain constant and are the same for all participants of the test, it creates an unfair advantage for taller individuals who are less challenged to jump from marker to marker. Therefore, leg length differences make this test difficult for comparison but are not accounted for.

Conclusion

Old tests get replaced by newer, more valid, and quite often, more reliable tests. This is what appears to have happened to the original Bass Balance Test. It got modified, but even this modified version is seldom in use due to obvious disadvantages. One subject gets less taxed throughout the jumping course than another, and the test does not control for arm sway or upper-body balance control actions. Collectively, this reduces the test’s sensitivity and reliability.

As a result, the Modified Bass Balance Test is not recommended in practice where valid and reliable balance results are desired. Check out our article on the “Multiple Single-Leg Hop-Stabilization Test” for a reliable variant of the Modified Bass Balance Test.

The post Modified Bass Balance Test appeared first on Science for Sport.

1. Summary
2. How do ACL injuries occur?
3. What is the Landing Error Scoring System (LESS)?
4. Why is the Landing Error Scoring System useful?
5. How do you conduct the Landing Error Scoring System?
6. How do you score the Landing Error Scoring System?
7. Is the Landing Error Scoring System valid and reliable?
8. Conclusion
9. References
10. About the Author

Summary

First presented in 2009, the Landing Error Scoring System (LESS) is a clinical tool used to assess jump-landing biomechanics. It was developed to identify individuals at risk of anterior cruciate ligament (ACL) injury (20) and is performed with a subject completing a Drop-Vertical Jump (DVJ) whilst video recorded from two planes (frontal and sagittal) (17). Being an easier, faster, and cheaper field-based variant of a complete biomechanical assessment (19), it can be performed without expensive laboratory equipment.

How do ACL injuries occur?

Despite the explosion of research on ACL injury during the last 30 years, the exact mechanism of injury is still not fully understood. However, a combination of internal (e.g. anatomic, hormonal, neuromuscular) and external factors (e.g. environment, footwear, ground, opposing players) may adequately explain the mechanism (8, 11).

The greatest strain on the ACL occurs during three-dimensional knee loading, which includes a knee extension moment, proximal anterior tibial shear force, knee valgus/varus moment, as well as a rotational contribution (18). After ACL reconstruction, altered movement mechanics in jump-landing tasks are often apparent (11) and have been shown to increase the risk of re-injury by 5-15 fold (10).

Focussing on particular movements that have been associated to ACL injury during landing tasks (11), such as valgus rotation at the knee joint, movements screens such as the LESS have been developed to identify athletes who may be at risk of sustaining an ACL injury (20).

What is the Landing Error Scoring System (LESS)?

The Landing Error Scoring System (LESS) is a relatively easy-to-use assessment tool to analyse the biomechanics of the lower extremities in a landing and jumping task. As a reliable clinical screening tool, it is described to offer the greatest value for the identification of individuals at risk of attaining non-contact ACL injury (20). However, recent research has questioned its ability to identify those at risk of ACL injury due to a lack of validity (9).

Based on a 19-point continuous scale (see FREE downloadable scoring sheet), the LESS assesses the positioning of the trunk and lower extremities at various stages through the Drop-Vertical Jump (DVJ) movement. Global fluidity and range of motion in the landing phase are analysed from frontal and sagittal plane video data. Movement patterns deviating from the ‘biomechanical optimum’ can possibly predispose an athlete to lower-extremity injuries (14). Those are scored as “error points”, and add up to a LESS score.

Poor landing technique is indicated by higher LESS scores (more “error points”) and vice versa.

Why is the Landing Error Scoring System useful?

As mentioned above, it is important to assess movement patterns that may predispose an athlete to ACL injury. As such, the LESS offers an accurate and inexpensive assessment of these movement concerns. Athletes identified as ‘at risk’ can then be directed towards specific training programmes designed to improve jump-landing mechanics in an attempt to reduce their risk of ACL injury.

Having said this, recent research assessing the effectiveness of the LESS for identifying ACL injury risk concluded it had limited predictive ability (8). This also lies in the generally low sensitivity and specificity of screening methods to this day.

It might be wishful thinking to try to predict future injuries in an otherwise healthy athlete (1). Movement screens cover just a small part of the ACL injury mechanism, most other factors cannot be screened for.

How do you conduct the Landing Error Scoring System?

It is important to understand that whenever fitness testing is performed, it must be done in a consistent environment (e.g. facility) so it is protected from varying weather types, and with a dependable surface that is not affected by wet or slippery conditions. If the environment is not consistent, the reliability of repeated tests at later dates can be substantially hindered and result in worthless data.

Required Equipment

• Consistent testing facility (e.g. gym or laboratory)
• Measuring tape
• Box: 30cm height
• Marking tape/sports tape
• Two off-the-rack video cameras (including a tripod/stand)
• Performance recording sheet (see FREE downloadable content)

Test Configuration

Figure 1 displays the test configuration for the LESS. This setup must be adhered to if accurate and reliable data is desired.

Test Procedure
The subject stands on a 30cm-high box half the body height away from the landing zone marked by a line on the ground. The subject is then instructed to jump forward so both limbs leave the box simultaneously aiming to land just past the line, and then jump for maximal height immediately after landing.

Video 1 demonstrates how the LESS is conducted and analysed.

Subjects can practice until comfortable with the task. No comment or guidance is provided unless performance does not follow the instructions. Any comment or judgment from the tester could disrupt the athlete’s performance and bias the test results.

Three trials should be recorded by two off-the-rack video cameras that are installed; one recording the subject from the front (A), and the other recording from the side (B). Each camera should be placed 3m away from the landing zone (Figure 1). The captured movement can then be evaluated at a later time.

How do you score the Landing Error Scoring System?

Based on a 19-point continuous scale (see FREE performance sheet), the LESS assesses the positioning of the trunk and lower extremities at various stages throughout the Drop-Vertical Jump (DVJ) movement. Using the performance recording sheet, the 1-15 items are scored dichotomically by adding either 1 or 0 to the final scores. Only items 16 and 17 add values 0, 1 or 2 depending on joint displacement and overall impression, respectively.

Therefore, a maximal score of 19 can be reached for exceptionally poor performances, while scores < 5 are regarded as “good” assuming low risk for ACL injury (8).

Is the Landing Error Scoring System valid and reliable?

The LESS was correlated against the gold standard, that is three-dimensional motion analysis (16) and showed good to excellent inter-rater and intra-rater reliability can be obtained (18, 20). LESS scoring of six items has “excellent” (84-100 %) agreement with 3D motion analysis (15).

LESS scores may vary widely in young athletes and military populations upon which the LESS was developed (17, 20). Clear cut-off values for LESS scores dividing low-risk groups from groups with a higher risk of obtaining ACL injury are thus difficult to establish. Commonly used cut-off values range between 5-5.5 (8). This results in ‘labelling’ athletes as low-risk with LESS scores of between 0 and 5, while a high-risk group contains individuals with a LESS score of 5 or higher. More studies must be conducted in the active population before normative data can be established (7).

It is being questioned whether the DVJ (which is not often associated with ACL injury itself (9)) is optimally challenging the knee while at the same time offering a safe, controlled and reproducible screening environment. More work should be done to provide enough evidence that increased knee motion during the drop vertical jump landing task actually increases the risk for non-contact ACL injury (20). Generic bilateral landing tasks (such as the DVJ) have limited predictive ability. To detect high-risk landing postures, sport-specific movements that are associated with ACL injuries may be a more appropriate approach to determining efficacy (9).

Repetitive screening is a big part of the job of a sports exercise and medicine clinician. Periodic health evaluations can show underlying pathologies and/or injuries, assess rehabilitation status and establish return-to-sport benchmarks for athletes (6). The utilisation of high-quality research tools to build an evidence base in sports exercise should focus on specific sports and relevant sub-groups (such as gender) (13), as well as on the topic of return-to-sport.

Conclusion

Despite its limitations, the LESS remains the instrument of choice in testing biomechanical behaviour to identify individuals with potentially ‘risky’ movement patterns. It is never the goal to expose athletes to high-risk tasks during testing. Even if it would offer better predictability, it also increases analysis and time burdens with screening.

The LESS is a method requiring minimal time and equipment (total set-up time per individual is under fiver minutes), and, is, therefore, applicable for a wide community. All evaluated movement patterns in the LESS actually increase the risk of attaining ACL injury in 3D motion analysis.

While all these evaluations seem confusing or misleading, they can be distilled down to one simple piece of advice, as below.

Use the LESS if:

1. You have limited time and money.
2. Work with a sporting population that has an increased risk of obtaining ACL injuries, due to repetitive jumping-landing manoeuvres.
3. Want a valid and reliable tool to assess landing mechanics.

Don’t use the LESS:

1. To predict an ACL injury and trigger fear-avoidance in an athlete.
2. Or, as a replacement for a thorough medical assessment.

The post Landing Error Scoring System (LESS) appeared first on Science for Sport.