About

Kornelia Kulig, PhD, PT, FAPTA, is a professor and clinical scholar at the USC Division of Biokinesiology and Physical Therapy. Her research is clinically motivated and experimentally tested, focusing on orthopedic conditions with recurrent symptoms such as low back pain and tendinopathies. She explores tissue morphology, physiology, and movement strategies across a broad range of activities, pathology stages, and populations. Her work serves as a framework for studying age- and activity-related degenerative processes, as well as peripheral and central adaptations and clinical presentations. Dr. Kulig is also the co-director of the Musculoskeletal Biomechanics Research Laboratory.

Research topics

• Medicine
• Physical medicine and rehabilitation
• Physical therapy
• Anatomy
• Psychology

Selected publications

• Regional alterations in Achilles tendon morphology in elite adolescent athletes with Achilles tendinopathy compared to matched controls

  Journal of science and medicine in sport · 2026-03-01

  articleOpen access

  OBJECTIVES: The study aims to analyze intra-tendinous micro-morphology measured with ultrasound image spatial frequency analysis in adolescent athletes with unilateral Achilles tendinopathy but without signs of tendon pathology on conventional ultrasound images. DESIGN: Cross-sectional study. METHODS: In this retrospective analysis of medical and tendon data from n = 1043 adolescent athletes, 31 cases diagnosed with Achilles tendinopathy were recruited. Datasets reporting bilateral symptoms, presence of image-based tendon pathology or inadequate imaging quality were excluded. Twenty-one adolescent athletes with Achilles tendinopathy were included. Subsequently, 21 age- and sport-matched pain-free controls with inconspicuous tendons on imaging were added from the database. Spatial frequency analysis with 8 parameters was performed on standard regions of interest at the tendon attachment and midportion. Additionally, the region of interest of structural irregularities at painful sites was investigated. Lower values of spatial frequency analysis parameters indicate increased fiber disorganization, and lower fiber density. Calculated parameters were compared using ANOVA (α < 0.05). RESULTS: The painful site showed significantly lower values in two parameters indicating fiber organization (p < 0.03) and one indicting fiber density (p < 0.01) compared to both standard regions of interest of the same tendon and the contralateral asymptomatic tendon. Compared to matched control tendons decreased values were seen for the painful site versus three parameters indicating fiber organization (p < 0.05) and one indicting fiber density (p < 0.01). CONCLUSIONS: Adolescent athletes with Achilles tendinopathy present altered intra-tendinous morphology at the painful tendon site. Conversely, standard regions of interest revealed comparable values to previous findings in healthy tendons of adolescent athletes. The results indicate that painful tendons, devoid of degeneration on B-mode ultrasound, have increased fiber disorganization and lower density, representing reactive tendinopathy.

  PublisherDOI

• Ultrasound imaging settings can optimize spatial frequency analysis and pathology discrimination in supraspinatus tendon

  Muscles Ligaments and Tendons Journal · 2026-04-13

  articleOpen access

  Purpose: Spatial frequency analysis (SFA) of ultrasound images quantitatively characterizes tissue morphology. However, the impact of machine settings on SFA for tendon pathology remains underexplored. We characterize how variations in settings influence SFA parameters in supraspinatus tendon images and identify which parameters differentiate between healthy and pathological tendons. Methods: Ten shoulders (5 with partial tears and 5 healthy) were imaged to examine how ultrasound settings (frequency, dynamic range, gain) influence SFA parameters. Tendons were scanned at 9 and 12 MHz with all possible dynamic range and gain combinations, resulting in 1680 images. Linear mixed-effects models analyzed the impact of settings on four SFA parameters. Results: SFA peak spatial frequency radius (PSFR) significantly differed between healthy and pathological tendons, regardless of settings (Coef. = 0.55, SE = 0.04, p &lt;0.001). 12 MHz frequency notably enhanced PSFR’s discriminatory power, showing higher values in healthy tendons (1.34 mm-1) and lower in partial tears (1.09 mm-1) compared to 9 MHz (1.22 mm-1 and 1.04 mm-1). P6, Q6, and Amax parameters were affected by machine settings. Conclusion: Optimal ultrasound settings enhance SFA’s ability to discriminate between healthy and pathological supraspinatus tendons, with PSFR as the most robust parameter. 12 MHz significantly improves pathology discrimination.

  PublisherOA PDFDOI

• Diagnostic domains, differential diagnosis and conditions requiring further medical attention that are considered important in the assessment for Achilles tendinopathy: a Delphi consensus study

  British Journal of Sports Medicine · 2025-04-16 · 12 citations

  articleOpen access

  The absence of agreed methods to diagnose Achilles tendinopathy impedes research and clinical practice. This gap results in heterogeneous and/or poorly described study samples, making it challenging to apply findings in clinical practice. The aim of this Delphi study was to define consensus on (1) diagnostic domains; (2) differential diagnoses; and (3) conditions requiring further medical attention, when assessing for Achilles tendinopathy.We conducted a sequential three-stage process which included: (1) identifying diagnostic domains, differential diagnoses and conditions requiring further medical attention based on existing scoping reviews and clinical practice guidelines; (2) developing Delphi survey questions; and (3) administering a five-round Delphi online survey. Consensus was defined as ≥70% agreement.52 participants completed the surveys. Four diagnostic domains were deemed essential and reached consensus (pain location (93%); pain during activity (97%); tests that provoke pain (87%); palpation to assess pain (83%)). 15 differential diagnoses reached consensus: 2 for both midportion and insertional (partial tear (80%); posterior ankle impingement (78%)), 6 for midportion (plantaris tendinopathy (84%); tibialis posterior or flexor hallucis longus tendinopathy/tenosynovitis (72%); flexor digitorum longus tendinopathy (77%); accessory soleus muscle (74%); paratendinopathy (86%); sural nerve neuropathy (81%)) and 7 for insertional (superficial (88%) and retrocalcaneal bursitis (86%); Haglund's/calcaneal exostosis (80%), intratendinous calcifications (73%); Sever's disease (78%); calcaneal stress reaction/fracture (80%); subtalar/ankle pain (71%)). Six conditions requiring further medical attention reached consensus: (Achilles tendon rupture (83%); systemic inflammatory joint disease (86%); metabolic syndrome (75%); familial hypercholesterolaemia (77%); endocrine and hormonal disorders (80%); drug reactions (77%)).This consensus identified essential diagnostic domains, differential diagnoses and conditions requiring further medical attention that should be considered when assessing for Achilles tendinopathy.

  PublisherOA PDFDOI

• Achilles tendon morphology adaptations in chronic post-stroke hemiparesis: a comparative analysis with neurologically intact controls

  Frontiers in Sports and Active Living · 2025-01-07 · 3 citations

  articleOpen access

  Introduction: In individuals with chronic post-stroke hemiparesis, slow walking speed is a significant concern related to inadequate propulsion of the paretic limb. However, an overlooked factor is this population's altered morphology of the Achilles tendon, which may compromise the propulsive forces by the paretic limb. This study aimed to explore changes in Achilles tendon morphology, including gross thickness and intra-tendinous collagen fiber bundle organization, following stroke-induced brain lesions. Methods: Fifteen individuals with chronic post-stroke hemiparesis (at least 6 months post-stroke) and 19 neurologically intact controls participated. Ultrasound imaging was used to evaluate Achilles tendon thickness and collagen organization in the paretic and non-paretic limbs of post-stroke participants, as well as in the right limb (control limb) of the neurologically intact control group. Results and discussion: Compared to control individuals, the paretic limb in individuals post-stroke showed increased tendon thickness at the Achilles tendon insertion and 2 cm above it. The collagen fiber bundle at the Achilles tendon insertion of the paretic limb showed reduced organization compared to that in the control limb. Individuals post-stroke also exhibited slower walking speed, and increased plantarflexor muscle tone in the paretic limb compared to controls. In conclusion, individuals with chronic post-stroke hemiparesis demonstrated tendon thickening and collagen disorganization in the paretic limb, particularly at the insertion site of the Achilles tendon, likely due to an abnormal loading environment influenced by increased plantarflexor muscle tone, muscle co-activation, and muscle disuse and atrophy. These changes may increase tendon compliance, impair force transmission and propulsion, and contribute to slower walking speed. Addressing Achilles tendon integrity should be incorporated as a component of strategies to improve neuromuscular control in this population.

  PublisherDOI

• Relationship Between Tendon Tissue and Shoulder Disability Change During an 8-Week Exercise Intervention for Rotator Cuff Tendinopathy: An Observational Study

  Physical Therapy · 2025-08-29 · 4 citations

  articleOpen access

  IMPORTANCE: Understanding how tendon structure relates to disability improvement during exercise interventions in rotator cuff tendinopathy is essential for optimizing individualized treatment strategies. OBJECTIVE: The objectives of this study were to characterize changes in supraspinatus tendon thickness and internal architecture over an 8-week resistive exercise intervention and evaluate the relationship between these changes and patient-reported shoulder disability. DESIGN: This was a prospective longitudinal observational study. SETTING: The settings were a university-based research laboratory and virtual supervision in participants' homes. PARTICIPANTS: Forty-seven adults with unilateral rotator cuff tendinopathy were the study participants. INTERVENTION: The intervention was an 8-week progressive resistive exercise program, supervised twice weekly by a physical therapist. MAIN OUTCOMES AND MEASURES: Primary outcomes were the Pennsylvania Shoulder Score, supraspinatus tendon thickness, and internal tendon architecture assessed using the peak spatial frequency radius via ultrasound. Measurements were taken at baseline and at 2, 4, and 8 weeks. Linear mixed-effects models were used to assess changes and associations. RESULTS: Significant improvements from baseline were observed for the Pennsylvania Shoulder Score at 2, 4, and 8 weeks. Tendon thickness decreased significantly; changes in internal tendon architecture were not significant. A decrease in tendon thickness was associated with an improved Pennsylvania Shoulder Score at 2 weeks but not at 4 and 8 weeks. CONCLUSIONS: Reductions in tendon thickness were associated with improved shoulder outcomes within the first 2 weeks of the intervention. Internal tendon architecture remained unchanged over the intervention. These findings suggest that tendon variables included in this study may be relevant only early in the intervention and that other factors should be investigated across different times of the intervention.

  PublisherOA PDFDOI

• Resistance Exercise Program Is Feasible and Effective in Improving Functional Strength in Post-Covid Survivors

  Preprints.org · 2024-02-20 · 2 citations

  preprintOpen accessSenior author

  Evidence suggests that COVID-19 infection can cause lasting health consequences. Multidiscipli-nary rehabilitation services have been recommended to reduce the sequalae. However, the effec-tiveness of physical exercise interventions remains insufficiently documented. The aim of this study was to develop and implement a specific and well tolerated protocol-based, intervention to reduce muscle weakness in older adults impacted by COVID-19. Forty six older adults random-ized into Intervention and Control Groups. Isometric and isokinetic strength assessments were conducted for selected muscle groups using JBA Staniak® torquemeter and Biodex System 3 dy-namometer. Functional abilities were evaluated with the Time Up and Go test and Chair Stand Tests. Men in intervention group demonstrated a significant improvement in static conditions for knee flexors (KF), trunk extensors (TE) and trunk flexors (TF) and in dynamic conditions for knee extensors (KE). Women in intervention group showed significant improvement in static condition for EF, KF, TE and TF and in dynamic for a KE and for a KF. The interaction GROUP x TESTING SESSION was significant for Chair test (s) and Chair test (n). Our results demonstrate the effec-tiveness of a well-tolerated, protocol-based approach that can be used to diminish long lasting functional deficits in post-covid survivors.

  PublisherOA PDFDOI

• Lower-Extremity Energetic Distribution During Rate-Controlled Ballet Jumps (Sautés) in Healthy Dancers

  Journal of Applied Biomechanics · 2024-01-04 · 2 citations

  articleSenior author

  Dancers frequently perform jumps in the context of a prolonged, continuous dance piece. The purpose of this study is to explore the lower-extremity energetics in healthy dancers performing repetitive dance jumps (sautés) before and after typical dance-specific choreography. Lower-extremity kinetic data were collected from 14 healthy female dancers during a series of sautés performed before and after 3 minutes of dance. Percent contributions of the lower-extremity joints to the whole-limb mechanical energy expenditure during ground contact were calculated. The jumps performed at the beginning were compared with the jumps at the end of the dance choreography. Dancers maintained the jump rate and consistent whole-limb mechanical energy expenditure between the jump series. As expected, for both jump series, the sautés had greater relative energetic contribution from the ankle and knee as compared with lesser contribution from the hip and toe. However, we observed lesser contribution from the knee and greater contribution from the hip after a 3-minute dance. After performing typical dance choreography, the dancers demonstrated a distal to proximal redistribution of individual joints’ contribution to whole-limb mechanical energy expenditure.

  PublisherDOI

• Resistance Exercise Program Is Feasible and Effective in Improving Functional Strength in Post-COVID Survivors

  Journal of Clinical Medicine · 2024-03-16 · 8 citations

  articleOpen accessSenior author

  Background: Evidence suggests that COVID-19 infection can cause lasting health consequences. Multidisciplinary rehabilitation services have been recommended to reduce the sequalae. However, the effectiveness of physical exercise interventions remains insufficiently documented. The aim of this study was to develop and implement a specific and well-tolerated protocol-based intervention to reduce muscle weakness in older adults impacted by COVID-19. Methods: Forty-six older adults were randomized into intervention and control groups. Isometric and isokinetic strength assessments were conducted for selected muscle groups using a JBA Staniak® torquemeter and Biodex System 3 dynamometer. Functional abilities were evaluated with the Time Up and Go test and Chair Stand Tests. Results: Men in the intervention group demonstrated a significant improvement in static conditions for knee flexors (KFs), trunk extensors (TEs) and trunk flexors (TFs) and in dynamic conditions for knee extensors (KEs). Women in the intervention group showed a significant improvement in static conditions for EFs, KFs, TEs and TFs and in dynamic conditions for a KE and a KF. The interaction GROUP × TESTING SESSION was significant for the Chair Test (s) and Chair Test (n). Conclusions: Our results demonstrate the effectiveness of a well-tolerated, protocol-based approach that can be used to diminish long-lasting functional deficits in post-COVID survivors.

  PublisherOA PDFDOI

• ICON 2023: International Scientific Tendinopathy Symposium Consensus – the core outcome set for Achilles tendinopathy (COS-AT) using a systematic review and a Delphi study of professional participants and patients

  British Journal of Sports Medicine · 2024-09-13 · 15 citations

  reviewOpen access

  To develop a core outcome set for Achilles tendinopathy (COS-AT) for use in clinical trials we performed a five-step process including (1) a systematic review of available outcome measurement instruments, (2) an online survey on truth and feasibility of the available measurement instruments, (3) an assessment of the methodological quality of the selected outcome measurement instruments, (4) an online survey on the outcome measurement instruments as COS and (5) a consensus in-person meeting. Both surveys were completed by healthcare professionals and patients. The Outcome Measures in Rheumatology guidelines with a 70% threshold for consensus were followed. We identified 233 different outcome measurement instruments from 307 included studies; 177 were mapped within the International Scientific Tendinopathy Symposium Consensus core domains. 31 participants (12 patients) completed the first online survey (response rate 94%). 22/177 (12%) outcome measurement instruments were deemed truthful and feasible and their measurement properties were evaluated. 29 participants (12 patients) completed the second online survey (response rate 88%) and three outcome measurement instruments were endorsed: the Victorian Institute of Sports Assessment-Achilles questionnaire, the single-leg heel rise test and evaluating pain after activity using a Visual Analogue Scale (VAS, 0-10). 12 participants (1 patient) attended the final consensus meeting, and 1 additional outcome measurement instrument was endorsed: evaluating pain during activity/loading using a VAS (0-10). It is recommended that the identified COS-AT will be used in future clinical trials evaluating the effectiveness of an intervention. This will facilitate comparing outcomes of intervention strategies, data pooling and further progression of knowledge about AT. As COS-AT is implemented, further evidence on measurement properties of included measures and new outcome measurement instruments should lead to its review and refinement.

  PublisherOA PDFDOI

• Flexor hallucis longus tendon morphology in dancers clinically diagnosed with tendinopathy

  Journal of Ultrasound · 2023-06-25 · 4 citations

  articleOpen accessSenior author

  PURPOSE: The unique demands of dance technique make dancers more prone to certain pathologies especially of the foot and ankle. Flexor hallucis longus (FHL) tendinopathy, colloquially known as "dancer's tendinopathy," is common in dancers and not well studied. The purpose of this study was to assess if morphological alterations in tendon structure occur as an adaptive response to dance activity by comparing the FHL tendon in dancers to non-dancers, and if pathology further alters tendon morphology in dancers clinically diagnosed with tendinopathy. METHODS: Three groups of ten participants were recruited (healthy non-dancers, healthy dancers, and dancers with FHL tendinopathy). Ultrasound images of the FHL tendons were analyzed for macromorphology by measuring the tendon thickness. The micromorphology was analyzed by determining the peak spatial frequency radius of the tendon. Our study did find increased tendon proper and composite tendon thickness in dancers with tendinopathy but no difference between asymptomatic dancers and non-dancers. RESULTS: There was no significant difference in micromorphology found between any of the groups. As expected, dancers with tendinopathy demonstrated increased composite tendon and tendon proper thickness however, there was no evidence of adaptive thickening of the FHL tendon as might be expected for the dance population. There was also no evidence of micromorphological changes in the presence of clinically diagnosed FHL tendinopathy. CONCLUSION: Because of the limited normative data for this pathology, these results can help improve diagnosis and therefore treatment for dancers to decrease the impact of this injury on their careers.

  PublisherOA PDFDOI

Frequent coauthors

• Todd E. Davenport

  University of the Pacific

  78 shared

• Joshua A. Cleland

  Tufts University

  71 shared

• Julie M. Fritz

  University of Utah

  70 shared

• John D. Childs

  Blackberry (United States)

  68 shared

• John Magel

  University of Utah

  66 shared

• Sarah Eberhart

  Southern California University for Professional Studies

  66 shared

• John M. Popovich

  Michigan State University

  25 shared

• Christopher M. Powers

  University of Southern California

  22 shared