The prospective observational study, led by Nathan J. Savage of High Point University with colleagues at North Carolina Agricultural and Technical State University and Winston-Salem State University, tracked sixteen athletes before the season and fifteen after it concluded. Each participant underwent diagnostic neuromusculoskeletal ultrasound imaging of four body regions: the shoulder, the anterior knee, the posterior ankle, and the plantar foot. The examiners measured supraspinatus tendon and plantar fascia thickness, along with cross-sectional area of the patellar and Achilles tendons, and recorded the presence or absence of tendinopathy and enthesopathy at each site.

Performance testing ran in parallel with the imaging. Athletes completed single-leg hops and single-leg vertical jumps, double-limb vertical jumps, thirty-centimeter drop jumps, broad jumps and double broad jumps, and the Closed Kinetic Chain Upper Extremity Stability Test, which counts alternating hand touches in a push-up position over fifteen seconds. Jump heights were derived from flight time recorded on video at sixty frames per second and analyzed with the Kinovea software package. Athletes also completed the Landing Error Scoring System for movement quality and two self-report instruments, the Recovery-Stress Questionnaire for Athletes and the Low Energy Availability in Females Questionnaire, which the researchers tested as contextual moderators of performance change.

The statistical approach centered on linear mixed-effects models with a random intercept for each athlete, allowing the team to separate individual differences from seasonal change. Single-leg hop distance and vertical jump height were standardized and averaged into limb-specific composite scores, although the authors cautioned that these composites reflect an athlete’s relative position within the cohort rather than absolute within-athlete change, so the individual component measures were also analyzed separately. Across all models, the variance partition coefficients were strikingly high, ranging from roughly 0.69 to 0.88 for lower-extremity outcomes and 0.90 for upper-extremity performance, meaning that most of the variability in performance belonged to stable differences between athletes rather than to time, tissue structure, or their interaction.

That clustering dominated the results. Conditional R-squared values reached approximately 0.74 to 0.89 for lower-extremity models and 0.91 for the upper-extremity composite, while marginal R-squared values, which capture the contribution of fixed effects such as tendon size and pathology status, remained below about 0.06. Neither continuous tendon measures nor categorical pathology indicators produced consistent main effects or Time-by-tissue interactions. The single significant interaction, involving left patellar tendon cross-sectional area and left single-leg hop, appeared in an exploratory model and was not supported by the broader pattern of results.

The descriptive data nonetheless revealed real seasonal shifts in both structure and performance. Achilles tendon cross-sectional area increased significantly on both sides, plantar fascia thickness rose bilaterally, and distal patellar tendon cross-sectional area increased on the left. Performance changes were task-dependent: left single-leg hop distance improved by nearly twenty-nine centimeters, while double-limb vertical jump, drop jump, and double broad jump measures declined modestly, and upper-extremity stability scores improved by nearly three repetitions. Single-leg hop symmetry fell by about ten percentage points. The authors emphasized that these paired comparisons were exploratory, based on a small pilot sample with multiple outcomes tested.

One of the most intriguing findings emerged from the secondary correlation analyses. Changes in right and left tendon measures were strongly coupled, particularly for the Achilles tendon, where Spearman correlation coefficients ranged from approximately negative 0.69 to 0.75. Athletes whose Achilles tendon grew on one side tended to show concordant growth on the other, a pattern the researchers interpret as consistent with sport-specific tendon adaptation to cumulative loading rather than limb-specific functional output. Yet these bilateral structural changes correlated only weakly, if at all, with changes in performance, with coefficients generally below 0.45 in magnitude and none reaching statistical significance.

The contextual monitoring variables fared no better as predictors. Landing Error Scoring System totals, recovery-stress scores, and energy availability questionnaires showed no association with double-limb performance and did not modify how performance changed across the season. An exploratory cross-sectional association between LESS scores and vertical jump height hinted at a possible link between landing mechanics and explosive capacity, but the absence of interaction effects indicated that movement quality scores did not shape the direction or magnitude of seasonal adaptation. The authors note that these tools are typically validated as independent screening instruments, not as moderators of structure-performance relationships.

The results align with a growing body of evidence that qualitative tendon abnormalities on ultrasound, such as hypoechoic thickening, disrupted fibrillar architecture, and intrasubstance defects, are common in asymptomatic jumping athletes and do not necessarily imply current functional impairment. Large cohort and meta-analytic studies suggest such findings may raise future pain risk, but their positive predictive value is low and definitions of abnormality vary widely across studies. In this cohort, tendinopathy indicators were present in a substantial fraction of athletes at both time points, including patellar tendinopathy in roughly two-thirds to more than three-quarters of tendons examined, yet pathology status did not distinguish performers from one another.

The authors are careful about scope. The study followed a single team, limiting statistical power for interaction tests and generalizability, and imaging was confined to grayscale morphology of selected tendons, entheses, and the plantar fascia, without shear wave elastography or muscle architecture measures that might capture complementary aspects of tissue composition and force production. Measurements were taken only at pre-season and post-season, so transient within-season fluctuations went unrecorded, and study-specific intra-rater reliability of the sonographic measurements was not formally established, although a single experienced examiner used standardized protocols. There was no control group of non-jumping athletes against which to benchmark tissue adaptation.

Within those limits, the practical message is one of interpretive caution. Sonographic abnormalities in asymptomatic athletes should not be read in isolation as signs of reduced performance or maladaptation, the researchers conclude. Instead, imaging findings belong within a broader athlete-monitoring framework that includes performance testing, movement quality, training exposure, and athlete-reported factors. For a sport in which connective tissue health is monitored closely, the study offers a quantitative reminder that what the tendon looks like on the screen and what the athlete can do on the court may be telling two different stories.

Subject of Research: Relationship between ultrasound-derived tendon characteristics and functional performance across a Division I women's volleyball season

Article Title: Sonographically derived tissue characteristics and functional performance adaptation across a competitive season in division I female volleyball athletes

Article References: Savage, N. J., Purdom, T., & Wendt, C. (2026). Sonographically derived tissue characteristics and functional performance adaptation across a competitive season in division I female volleyball athletes. Frontiers in Sports and Active Living, 8, 1957488. https://doi.org/10.3389/fspor.2026.1957488

Image Credits: AI Generated

DOI: 10.3389/fspor.2026.1957488

Keywords: volleyball, ultrasound imaging, tendon adaptation, Achilles tendon, patellar tendon, jump performance, athlete monitoring, tendinopathy, plantar fascia, mixed-effects models, female athletes, sports science