July 2024

Baseline for Success – functional movement tests and reference data as a starting point for youth athlete development


In competitive sports, everyone pushes their limits. Through regular baseline screenings using functional movement tests and performance tests on the lower extremities, medical and sports staff receive valuable information to push these limits further and enable athletes to achieve successful athletic development.

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Screenings as investment?

Is the heading only a bold metaphor for elite sports or yet state-of-the-art for all performance levels? It is an undisputed fact that an athletes in competitive sports not only compete for victory but also battle their own physical limits. Regular baseline screenings using functional movement tests and performance tests on the lower extremities provide valuable information to medical and sports professionals to push these limits and enable successful athlete development (1). Without a screening history at hand, or for reasons of comparing athletes’ performances, reference values become a valuable source for interpreting performance individual performance metrics.

The December 2022 issue of the German pt magazine featured the article “The trainer in your shoe” and discussed how mobile sensor insoles can be used for biomechanical motion analysis to obtain objective metrics for functional movement tests and performance tests (2, Vid-1). The approach opens up various opportunities for individualized athlete care. Initial baseline screenings can reveal new performance potentials (3). Integrating tests as part of pre-injury screenings (PRE) allows for early detection of injury risks (4). Functional deficits in the musculoskeletal system post-injury can be reliably identified and made available ad-hoc to physical therapists (5). Objective measurement data and re-tests enable evidence-based interventions and targeted load management. However, medical and sports science expertise remains essential for meaningful interpretation of the data, along with meeting important quality criteria for the measurement technology itself.

Vid-1: Random athletes showing largely different outcomes, tested on a Single Leg Jump Distance test during reference data acquisition project discussed in this article.

A comprehensive history of key performance indicators from baseline screenings, such as stability, reactive strength, or agility, can be, in the very sense of the headline, literally invaluable for athletes.

Areas of interest in youth performance sports

This article discusses how new, flexible, and cost-efficient measurement methods can improve athlete development in youth performance sports and the value of publicly accessible comparative data for sports practice. The article provides initial insights into the results of an ongoing research project.

According to contributions from sports doctors, trainers, and physiotherapists at German conferences of institutions like GOTS, the Athletic Trainer Conference, or the OS Institute, there is still significant room for improvement in objectifying and documenting training data in youth performance sports. Most methods currently used in practice involve cardiovascular aspects in sports medical examinations, such as performance ECG combined with lactate measurements. The continuous use of professional biomechanical testing methods known from elite sports is limited by financial constraints and the complexity of the systems. However, the foundation for future sports stars is laid in youth sports. Therefore, it is more than worthwhile to take a closer look on this area.

About the importance of reference data

Given the current lack of comprehensive data on baseline screenings in club and individual sports, open-access reference values offer a valuable starting point for evaluating individual athlete performances. The following three case studies reflect typical situations in youth performance sports. The results section revisits the questions using statistical measurement data from the described study.

Starting point for athletic training

Objective assessment of athletic skills is often challenging for youth athletic trainers due to high interindividual variances and the lack of objective comparative values. For example, if a baseline screening identifies deficits in reactive strength development in the stretch-shortening cycle (SSC), global reference values can provide an ambitious target and motivation for specific training management.

Case 1 – the basketball trainer

“I coach our male U19 basketball team. Our athletes often lose out on crucial rebounds against the defense, even though they have good physical conditions. I developed a training program with our athletic trainer to work on reactive jump strength, but I wonder how to objectively track progress and how well opposing teams perform.”

Starting point for preventive measures

For identifying injury risks through baseline screening, it’s crucial to have critical thresholds for metrics and consistently and reproducibly determine athletes’ current status. In youth sports, the potential to correct misguided physical development early on can reduce injury risks, given the not yet fully established movement engrams. Significant differences in left-right comparison in unilateral tests, such as neuromuscular control in maximum horizontal jumps, can prompt preventive measures.

Case 2 – the tennis coach

“I am a tennis coach currently training our club’s female youth players. My 17-year-old player is progressing rapidly and might soon make it to the DTB squad. However, I am concerned about potential injury risks, especially since her non-dominant leg often seems weaker and unstable during sudden jumps and landings in volleys or sprints with sharp direction changes. To prevent serious injuries, we are using single-leg horizontal jump tests to isolate which neuromuscular imbalances have developed. But some asymmetry is always present, especially in tennis players. I’m interested in knowing when it becomes critical and how my athlete compares.”

Starting point for return-to-sport

The average values of a reference cohort can serve as a target for the return-to-sport phase if there are no own baseline screening values. This case study relates to stability during landing after the Balance Front Hop:

Case 3 – the soccer team physical therapist

“I am a sports physiotherapist for our youth soccer team in the regional league. My 18-year-old athlete suffered an anterior cruciate ligament (ACL) rupture in his left leg during a one-legged landing after a header three months ago. It was surgically repaired immediately. During current exercise sessions to increase load, we are using sports motor tests with sensor insoles to better manage the load increase. The injured side shows insufficient stabilization after landing in the Balance Front Hop, and even the healthy side doesn’t seem optimal as a reference. I’m interested in how comparable healthy athletes perform so I can improve postural control in rehabilitation.”

Study design for multifactorial reference database

This study aims to provide answers for sports practice users by creating a multifactorial database with reference values for the outcomes of key sports motor tests on the lower extremities. Multifactorial means that the study design is open regarding the inclusion of different sports and performance levels, as well as gender, age, and injury history. This approach benefits various sports and allows for cross-sport comparisons.

Framework, study type, and population

The research project is funded by the Bavarian State Ministry for Economic Affairs, Regional Development, and Energy. All organizations meeting the study criteria are continuously admitted as sports partners for data collection. This includes, among others, the Red Bull Athlete Performance Center, the German Ski Association, several Olympic training centers, and numerous sports clubs in Europe and the USA. Data collection for reference values is designed as an exploratory cross-sectional study, currently including all female and male athletes born in 2009 (U15) or older who practice a sport involving the lower extremities at a competitive level and are medically cleared for the tests. No exclusion criteria were set.

Measurement methods for motion analysis and metadata

The primary measurement method is the ReGo system, based on wireless sensor insoles with sensors for plantar pressure distribution and inertial sensors combined with pattern recognition algorithms. This system standardizes and automatically determines kinetic parameters (e.g., jump strength) and temporal and kinematic parameters (e.g., ground contact time and jump distance). To increase validity for highly dynamic movements, the measurement frequency was raised from 100 Hz to 200 Hz, and an improved calibration procedure was introduced (6).

As a comparison system for distance measurement (e.g., jump distance), the study uses the OpenCap optical 3D motion analysis system from Stanford University, USA. This system only requires three smartphone cameras for recording, with frame rates of 120 Hz or 240 Hz, depending on the test type. For future users in competitive sports, video analysis is no longer necessary.

Metadata such as age, gender, weight, and injury history are collected using a digital questionnaire. Automated motion analysis eliminates the often error-prone manual recording of measurements or counting repetitions. This provides a well-controlled, valid measurement setup with reproducible test conditions for mobile use in gymnasiums or outdoors (Fig-1).

Fig-1: Measurement setup for data collection in reference database project.

Test protocol for data collection

All athletes undergo a standardized protocol, including a questionnaire for meta-information, a warm-up program, calibration of measurement methods, and seven sports motor tests. Only the following tests are considered for the three case studies (Tab-1).

Drop JumpStart point strength & conditioning training
Single Leg Jump DistanceStart point prevention
Balance Front HopStart point return to sport
Tab-1: Exemplary functional tests and performance tests included for reference data collection.

Athletes are instructed to perform all tests in maximum or optimal form. The Drop Jump Test was selected for the basketball case study to test quick strength development (7). The Single Leg Jump Distance Test was chosen for its relevance to unilateral, maximum neuromuscular control (8). The Balance Front Hop is an established method for testing leg axis stability after ACL injuries (9).

Primary purposes of the Drop Jump Test (Fig-2) are plyometrics and reactive strength. The starting position is an elevated platform with one leg hanging down. Then, a two-legged drop is performed with maximum vertical rebound. After landing, the test subject stands in an upright position. The primary test goals are minimal ground contact time and maximum jump height.

Fig-2: Drop Jump test sequence.

Primary purposes of the Single Leg Jump Distance Test (Fig-3) are explosive power and landing quality, as well as a left/right comparison. The starting position is a single-leg stance. Then, a maximal horizontal jump is performed. The landing position is held. The same execution applies to both legs. The primary test goals are maximum jump distance and stable landing.

Fig-3: Single Leg Jump Distance test sequence.

Primary purposes of the Balance Front Hop Test (Fig-4) are control of the leg axis and a left/right comparison. The starting position is a single-leg stance. Then, a submaximal horizontal hop with a defined hop distance is performed. The landing position is held. The same execution applies to both legs. The primary test goals are quick stabilization after landing and reduced compensatory movements.

Fig-4: Balance Front Hop test sequence.

Improved comparability through standardization

The value of reference data depends on comparability with data collected in sports practice. High standardization is necessary for meaningful comparisons between athletes. Therefore, data collection for reference values follows strict guidelines for movement execution.

This particularly concerns the position of arms and hands. To make results less dependent on upper body anthropometry and better isolate strength and neuromuscular control in the lower extremities, hands should be placed on the hips during test execution (10). Despite this limitation, free arm positioning is often preferred in practice for many jump and hop tests.

Test descriptions and movement sequences

In summary, the following guidelines were used for the three functional movement and performance tests (Tab-2).

Standardization ItemConstraint
Hand positionHands remain on the hips during test execution
Hold phases3 seconds hold phase after landings
Repetitions3 repetitions per test or per leg
Drop Jump drop height30 cm platform height
Balance Front Hop hop distance40 cm hop distance
Tab-2: Constraints for movement tests.

Movement sequences, test descriptions, and other instructions and countdowns for starting or holding times are conveyed through app-controlled visual and acoustic instructions.

Results and discussion for youth performance sports

The presented results should be considered preliminary due to the ongoing data collection of the underlying project. Given the currently limited but age- and performance-level-homogeneous athlete population (Tab-3, Tab-4) and refinements in calculating metrics, changes in the ultimate statistics are likely. It is also worth noting that complete postural control, such as the vertical body axis during the Balance Front Hop test, cannot be measured in full with sensor insoles alone; additional evaluations by coaches or therapists are necessary. Nonetheless, some interesting insights have already emerged from the measurement data.




Tab-3: Basic statistical data of the study population at the date of processing (April 26th, 2023), age indicated in years, height in cm, weight in kg.
Performance LevelShare Total Population (%)
No indication1.1
Junior team (professional level)77.3
Tab-4: Performance levels of study population.

In all three case studies, initial biomechanical measurements were recorded to document the baseline state and reveal the athletes’ deficits. For Case Study 1, the result of a random athlete from the team is shown. A good to very good measurement result, which may come from a different sport, is provided for comparison as shown in Tab-5.

Reference values for athletic training

Considering the low reactive strength in Case Study 1 (Fig-5a), we can provide the U19 basketball team’s coach with the following insights regarding the reference values (Tab-5, highlighted cells):

  • The maximum Reactive Strength Index (RSI) value in basketball is 1.64, much higher than the sample athlete’s initial value of 0.82. This means the athlete is below the basketball comparison group average.
  • The highest RSI value in the overall study population is 2.99, which is 3.64 times higher than the initial measurement. Reactive strength appears significantly higher in other sports.

These results may be surprising at first but are plausible considering many jump situations in basketball start from a low stance with a compression phase. Comparing this to typical postures in reactive jumps in soccer highlights this (Vid-2). High reactivity is crucial in game-deciding situations, so the Drop Jump Test is also used as a performance test in the NBA professional league (11). The youth coach is advised to enhance the athletes’ reactive strength through targeted plyometric training and possibly integrate training methods from soccer.

Vid-2: Random basketball player (left) vs. soccer player (right) performing Drop Jump test.

Reference values for prevention

In Case Study 2, the initial measurement of the young tennis player revealed asymmetries in landing stability and absolute jump distance (Fig-5b). The reference values provide the coach with the following intervention points (Tab-3, lines 2/3, highlighted cells):

  • The best values for maximum jump distance (0.690m) and minimal Balance Sway Area (2.8%) in the tennis comparison group are top-tier compared to the overall study population.
  • The athlete’s non-dominant leg jump distance (0.584m) and Sway Area (17.0%) are significantly below the comparison group’s averages (0.613m, 8.3%).
  • The dominant leg shows excellent jump power (0.640m) and good landing stabilization (3.3% Sway Area).

Comparing with specific training methods from other sports isn’t initially suggested. For injury prevention, the coach should focus on dynamic stabilization exercises for the non-dominant leg to reduce the risk of ACL rupture during dynamic direction changes. The single-leg jumps used in the initial test are a good training method for this. Regular re-tests should be conducted as planned to monitor progress.

Reference values for return-to-sport

The 18-year-old soccer player from Case Study 3 shows significant instability in the Balance Front Hop Test for the ACL-ruptured leg compared to the healthy leg (Fig-5c, left). The reference values specify the following (Tab-3, lines 4/5, highlighted cells):

  • The healthy right leg has a good Sway Area value of 3.1%, with the average reference value at 6.1%.
  • The injured leg has a Sway Area of 12.2%, far above the acceptable average reference value.
  • Throughout the 3-second hold phase post-landing, no stabilization occurs, failing to meet the minimum requirement for Stabilization Progression. Athletes in the comparison group stabilize on average after 1.15 seconds.

There is no need for intervention on the healthy leg’s functional stability at the foot contact point, contrary to the physical therapist’s suspicion. The injured leg does not meet the stability test criteria for further load increase. The physical therapist should start with lower-intensity load exercises, such as single-leg squats, and progress to sub-maximal dynamic stabilization exercises.

Outlook on the performance sports reality

The case studies provide a glimpse into the opportunities for enhancing performance and athletic training opened up by building a reference database. The study aims to include around 1,000 athletes and integrate more speed and agility tests, such as a variable sprint test and the 505 agility test. This will cover crucial areas of athlete development in sports practice, from gait training and load increase post-injury to coordination training, strength aspects, and highly dynamic load changes and agility. The shown results are the beginning of a long journey that will gradually enable all youth sports coaches to optimally support their athletes and involve the athletes more through easier access to testing methods. If the described tensions can be resolved with sufficiently valid, flexible, and cost-effective biomechanical testing methods, significant opportunities arise for the future of competitive sports.


1. Dewitz, H., et al. 2018. Biomechanisches Screening zur Verletzungsprävention. Unfallchirurg. 121: 455-462. https://doi.org/10.1007/s00113-018-0498-3 

2. Ziegler, R., Müller, M. 2022. Trainingsprofi im Schuh – Sensoren zur Objektivierung von Testungen im Leistungssport. pt Zeitschrift für Physiotherapeuten. 74: 18-27 

3. Hauke, D., et al. Biomechanische Baseline-Testungen. Sportärztezeitung. URL: https://sportaerztezeitung.com/rubriken/training/6249/biomechanische-baseline-testungen (entnommen am 29.04.2023)

4. VBG 2015. Präventivdiagnostik für den bezahlten Sport – Testmanual zur Präventivdiagnostik im Rahmen des VBG Prämienverfahrens. Hamburg: VBG 

5. Keller, M., et al. 2016. Interdisziplinäre Beurteilungskriterien für die Rehabilitation nach Verletzungen an der unteren Extremität: Ein funktionsbasierter Return to Activity Algorithmus. Sportverletz Sportschaden. 30(01): 38-49

6. Cramer, LA, et at. 2022. Validity and reliability of the insole3 instrumented shoe insole for ground reaction force measurement during walking and running. Sensors 22, 2203

7. Reiser, R.F., et al. 2006. Building a Better Understanding of Basic Mechanical Principles Through Analysis of the Vertical Jump. Strength and Conditioning Journal. 28(4): 70–80

8. Janewanitsataporn, S. 2020. The Functional Tests after ACL Reconstruction with and without Meniscal Repair. JHSMR. 38(2):

9. VBG 2015. Return-to-Competition – Testmanual zur Beurteilung der Spielfähigkeit nach Ruptur des vorderen Kreuzbands. Hamburg: VBG

10. Laffaye, G., et al. 2006. Upper-limb motion and the drop jump: Effect of expertise. J. Sp. Med. Phys. Fit. 46, 2: 238-247

11. Bobbert, M. 1990. Drop Jumping as a Training Method for Jumping Ability. Sports Medicine. 9: 7-22

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