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Sensorimotor Predictors of Static and Dynamic Postural Control in Young Adults: A Cross-Sectional Analysis of Center-of-Pressure and Y-Balance Measures

This cross-sectional study of 65 young adults reveals that sports participation is the primary predictor of superior dynamic balance and reduced center-of-pressure sway, whereas visual reliance and inter-limb symmetry showed no significant association with performance.

Original authors: Yan Bu, Junhui Zhu, Panyang Mu, Mingling Zhao

Published 2026-06-28

📖 4 min read☕ Coffee break read

CC BY 4.0

Original authors: Yan Bu, Junhui Zhu, Panyang Mu, Mingling Zhao

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ⚕️ This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer

The Big Picture: The "Balance Gymnast" vs. The "Casual Walker"

Imagine your body's balance system is like a tightrope walker. To stay on the rope, your brain has to constantly make tiny adjustments using three main tools:

Your eyes (seeing where you are).
Your feet and legs (feeling the ground).
Your inner ear (knowing which way is up).

This study asked a simple question: Does being a regular athlete make you a better tightrope walker than someone who just goes to the gym occasionally?

The researchers looked at 65 young adults (mostly college students). They split them into two groups:

The "Athletes": People who had been training on a sports team or professionally for at least two years, practicing 8+ hours a week.
The "Non-Athletes": People who didn't play organized sports and exercised less than two hours a week.

The Three Tests They Ran

To see who had better balance, the researchers gave everyone three different types of tests, like checking different parts of a car engine.

1. The "Stillness Test" (Static Balance)

What they did: They asked people to stand perfectly still on a special floor that measures every tiny wobble (like a scale that records your shaking). They did this with eyes open and eyes closed.
The Analogy: Imagine trying to balance a stack of Jenga blocks on your head. The "Athletes" wobbled much less than the "Non-Athletes." Their "stack" was steadier.
The Result: The athletes were significantly steadier, especially when standing on two feet or one foot with their eyes open.

2. The "Reach Test" (Dynamic Balance)

What they did: They used the Y-Balance Test. Imagine standing on one leg and reaching as far as you can with your other foot in three directions (forward, back-left, back-right) without falling.
The Analogy: This is like trying to grab a cookie from a high shelf while standing on one leg.
The Result: The athletes could reach much farther than the non-athletes. They were more flexible and stable when moving.

3. The "Eye-Reliance Check" and "Leg-Symmetry Check"

What they did: They checked if athletes relied less on their eyes (by seeing how much they wobbled when eyes were closed) and if their left and right legs were perfectly symmetrical.
The Analogy:
- Eye-Reliance: Do you need to look at the ground to walk, or can you feel it?
- Symmetry: Is your left leg just as strong as your right?
The Result: Surprisingly, there was no difference between the groups here. The athletes didn't rely less on their eyes than the non-athletes, and their legs weren't more symmetrical.

The "Secret Sauce": What Actually Predicted Success?

The researchers used some fancy math (like a detective sorting through clues) to figure out what actually made the difference.

The Clue: They looked at age, height, weight, foot shape, and how much people wobbled while standing still.
The Verdict: The only thing that consistently predicted who had the best "Reach Test" (dynamic balance) was whether they were an athlete or not.

Even though the athletes stood stiller and reached farther, the study found that standing still perfectly (static balance) didn't automatically mean you could reach far (dynamic balance). They are like two different skills: one is being a statue, the other is being a gymnast. You can be good at one without being great at the other.

What This Means (According to the Paper)

The paper concludes that for young, healthy adults:

Sports training makes you a better "gymnast" (dynamic balance) and a steadier "statue" (static balance).
It does NOT necessarily make you less dependent on your eyes.
It does NOT necessarily make your legs perfectly symmetrical.

The researchers suggest that if you want to improve your balance, just standing still and staring at a wall might not be enough. You probably need the kind of active, moving training that athletes do, which builds strength and coordination in a way that simple standing tests can't measure.

Important Note: The paper is very careful to say this is a "snapshot" in time. They found a connection, but they didn't prove that joining a sports team caused the better balance (though it's likely). They also noted that because the study was small and cross-sectional, these findings are more like "promising hints" than final rules for doctors or coaches to follow immediately.

Technical Summary: Sensorimotor Predictors of Static and Dynamic Postural Control in Young Adults

Problem Statement
Static and dynamic postural control are fundamental to motor performance and lower-limb injury prevention. While Center-of-Pressure (COP) metrics quantify quiet standing stability and the Y-Balance Test Lower Quarter (YBT-LQ) assesses dynamic balance, the joint relationship between these measures, visual reliance, foot morphology, and inter-limb symmetry in healthy young adults remains insufficiently characterized. Existing literature often examines these metrics in isolation, lacking a unified framework to determine how sports participation background influences this multidimensional profile and whether static measures predict dynamic performance. Furthermore, it is unclear if general sports participation reduces visual reliance or alters inter-limb symmetry compared to non-participants.

Methodology
This cross-sectional observational study analyzed 65 young adults (aged 17–22 years; 42 women, 23 men) recruited from Yibin University. Participants were stratified into a sports-participation group ( $n=32$ ), defined by at least two years of systematic varsity or professional training with an average load of $\ge$ 8 hours/week, and a non-sports group ( $n=33$ ), engaging in $<$ 2 hours/week of moderate-to-vigorous activity.

Data Collection:

Anthropometrics: Height, mass, BMI, leg length, and foot arch index (via footprint method).
Static Postural Control: COP trajectory length, mean velocity, and 95% confidence-ellipse sway area were recorded over 30 seconds using a force platform under six conditions: bipedal and unipedal (right/left) stance with eyes open (EO) and eyes closed (EC).
Visual Reliance: Quantified using Romberg ratios (COP velocity change from EO to EC) for bipedal and unipedal conditions.
Dynamic Balance: Assessed via the YBT-LQ in anterior, posteromedial, and posterolateral directions. Reach distances were normalized to leg length to calculate composite scores.
Symmetry: Static and dynamic symmetry indices were calculated based on side-to-side differences in COP velocity and YBT composite scores.

Statistical Analysis:

MANCOVA: Evaluated the overall effect of sports participation on five dependent variables (YBT total score, bipedal EO/EC COP velocities, static/dynamic symmetry) while adjusting for age, sex, BMI, leg length, and foot arch index.
Exploratory PCA: Performed on 25 standardized balance variables to extract core dimensions of postural control.
Regression Modeling: Multiple linear regression and LASSO regression (with five-fold cross-validation) were used to identify predictors of the YBT total score.

Key Results

Multivariate Effect: MANCOVA revealed a significant multivariate effect of sports participation on the balance profile ( $Wilks' \Lambda = 0.625, P < 0.001$ ), with a multivariate partial eta squared of 0.375.
Static vs. Dynamic Performance:
- The sports-participation group demonstrated significantly lower COP velocities and sway areas compared to the non-sports group, particularly during bipedal EO and EC standing, and right unipedal EO standing.
- The sports group achieved significantly higher YBT total scores ( $94.2 \pm 9.2\%$ vs. $86.0 \pm 8.4\%$ of leg length; $P < 0.001$ ).
Null Findings: No significant between-group differences were found in visual reliance (Romberg ratios) or inter-limb symmetry indices ( $P > 0.05$ ).
Dimensional Structure: PCA extracted five components explaining 77.4% of the variance. Notably, the dynamic balance dimension (PC4) was driven almost exclusively by YBT variables, while static sway dimensions (PC1–PC3) were dominated by COP variables, suggesting these are complementary rather than interchangeable constructs.
Predictors of Dynamic Balance: In both multiple linear regression and LASSO regression, sports participation was the only statistically significant independent predictor of YBT total score (Standardized $\beta = +0.61$ in multiple regression; retained as the sole non-zero predictor in LASSO). Anthropometric variables, COP velocities, visual reliance, and symmetry indices did not provide stable independent explanatory value beyond sports participation.

Significance and Claims
The authors conclude that in young adults, sports participation is associated with a multidimensional postural-control profile characterized primarily by reduced COP sway amplitude and superior dynamic balance performance, rather than by reduced visual reliance or greater inter-limb symmetry.

The study posits that the association between sports participation and dynamic balance is not fully mediated by the measured static COP, visual, or symmetry variables, potentially reflecting unmeasured factors such as lower-limb strength, neuromuscular coordination, and motor-skill proficiency. Consequently, the paper suggests that balance assessment and training programs for young adults should consider sports-participation background alongside complementary static and dynamic measures.

Limitations and Cautions
The authors explicitly state that due to the cross-sectional design, findings represent associations rather than causal evidence. They caution that the sample size (65 participants) relative to the number of variables limits the generalizability of the PCA and regression results, which should be viewed as exploratory. Additionally, the lack of sport-specific stratification may have obscured specific patterns of visual reliance, and the study did not measure underlying mechanisms like muscle activation or proprioception. The authors emphasize that future longitudinal or intervention studies are required to verify causal effects.

The Big Picture: The "Balance Gymnast" vs. The "Casual Walker"

The Three Tests They Ran

The "Secret Sauce": What Actually Predicted Success?

What This Means (According to the Paper)

Technical Summary: Sensorimotor Predictors of Static and Dynamic Postural Control in Young Adults

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