There is a clearly established role of ultrasound imaging in traditional medical contexts to optimize patient assessment and subsequent care. These same applications have been carried over into sports medicine settings, especially with recent developments in ultrasound portability. Such technological advancements enable athletic trainers and other sports medicine clinicians to perform sideline assessments for athletes who sustain musculoskeletal injuries during sports.

Beyond diagnostic applications of ultrasound imaging, sports medicine clinicians and researchers have begun to adopt this tool as a creative means to assess musculotendinous structures in response to sport and exercise. Ultrasound imaging has advantages over other measurement techniques given that it is relatively inexpensive equipment, fairly easy to operate (especially if you know your anatomy!), and can be rapidly implemented into assessments. Ultrasound imaging also enables clinicians to perform more dynamic assessments with patients to understand functional movement patterns, and noninvasively examine deeper tissue structures. The real-time visual platform uniquely provides the opportunity to enhance patient-clinician dialogue and provide feedback to target key muscle groups during fundamental exercises.

Below, several exemplary studies that leverage ultrasound imaging in musculotendinous contexts are presented to convey the depth and breadth of innovation in the sports medicine field and highlight opportunities for future ultrasound implementation into practice.

Muscle Morphology

Ultrasound has been most frequently implemented in sports medicine research to conduct table-top assessments of musculotendinous structures. This measurement approach provides insights to clinicians on patients’ muscle and tendon changes in response to exercise (eg, weight- and height-adjusted size, fiber arrangement and quality). For example, researchers have been able to examine lower limb musculotendinous responses across long-distance running training.^1,2 Beyond training adaptations, clinicians are also able to get some insights into structural tissue changes in the presence of current or future musculoskeletal injury. This has specifically been done to examine musculotendinous adaptations at the shoulder complex,³ foot complex,⁴ and lumbopelvic hip complex⁵ across a range of pathological populations. Preliminary work has begun to identify signals in tendon tissue quality that relate to future pain in running athletes.¹ Such studies will continue to help inform rehabilitative and training interventions to improve muscle and tendon quality to move toward injury risk reduction in sports medicine.

Dynamic Muscle Function

In addition to the role of ultrasound imaging in more static imaging contexts, ultrasound has been implemented in sports medicine research in more functional contexts. Researchers have inventively started to use foam blocks with Velcro elastic belts to secure portable ultrasound probes on patients to visualize deep lumbopelvic hip muscles across a range of exercises and movements to assess the role of these muscles during fundamental movements (Figure).⁶ Through this approach, researchers have examined athletes’ transverse abdominis muscle thickness during an abdominal draw-in maneuver across patient positions to determine which activity elicited the most “bang for your buck” in muscle activity.⁷ Additionally, this measurement approach has been used to assess gluteal muscle function throughout treadmill walking. In these instances, ultrasound videos were obtained to quantify muscle activity throughout movement and identify activity dysfunction among patients with lower limb injuries.8,9 These examples emphasize the utility of ultrasound imaging to supplement typical sports medicine clinical assessments and underscore the opportunity for clinicians to implement ultrasound imaging in more dynamic assessments.

Real-time Feedback

Ultrasound imaging demonstrates great promise as a rehabilitative feedback tool for patients who have difficulty recruiting specific muscle groups as a result of injury.¹⁰ The most robust use of ultrasound for feedback has been taking dynamic assessments of the lumbopelvic hip complex muscles a step further and using ultrasound to allow patients to visualize their muscles during abdominal contraction exercises. In this manner, clinicians have been able to show patients their muscle activity, and encourage activation of select muscles during rehabilitative exercises. This approach has been found to be more successful for patient neuromuscular education than other feedback approaches, such as verbal encouragement. The visual interface not only helps patients to see and understand muscle recruitment in real time but also helps clinicians to see when patients are able to activate proper stabilizing muscle groups as opposed to “cheating” on an exercise and using global movers to achieve a movement. While there is less available information on the use of ultrasound for feedback for targeting other muscle groups during rehabilitation, these studies highlight the opportunities for ultrasound imaging to maximize patient benefit during clinical interventions.

The Future of Ultrasound in Sports Medicine

Ultrasound imaging can clearly play a key role in sports medicine assessments and interventions. Continued research is necessary to broaden our understanding of musculotendinous changes in relation to sports injuries and rehabilitation, as current research is still scraping the surface of ultrasound opportunities in sports. Ultrasound assessments may complement other forms of athlete assessments and provide more in-depth insights into muscle and tendon function in relation to performance and injury. It is plausible that with continued technological advancements and the miniaturization of ultrasound units, clinicians may be able to use imaging during more sport-specific activities at higher velocities to unearth real-time musculotendinous changes in physical activity. The prospects of ultrasound are promising, and this tool may continue to revolutionize patient care in sports medicine clinics.

References

1. Cushman DM, Petrin Z, Eby S, et al. Ultrasound evaluation of the patellar tendon and Achilles tendon and its association with future pain in distance runners. Phys Sportsmed. 2021; 49:410–419. doi:10.1080/00913847.2020.1847004.
2. DeJong Lempke AF, Willwerth SB, Hunt DL, Meehan III WP, Whitney KE. Adolescent marathon training: prospective evaluation of musculotendinous changes during a 6-month endurance running program [published online ahead of print September 29, 2022]. J Ultrasound Med. doi:10.1002/jum.16105.
3. Thomas SJ, Blubello A, Peterson A, et al. Master swimmers with shoulder pain and disability have altered functional and structural measures [published online ahead of print April 13, 2021]. J Athl Train. doi:10.4085/1062-6050-0067.21.
4. Fraser JJ, Koldenhoven R, Hertel J. Ultrasound measures of intrinsic foot muscle size and activation following lateral ankle sprain and chronic ankle instability. J Sport Rehabil 2021; 30:1008–1018. doi:10.1123/jsr.2020-0372.
5. Dieterich AV, Deshon L, Strauss GR, McKay J, Pickard CM. M-Mode ultrasound reveals earlier gluteus minimus activity in individuals with chronic hip pain during a step-down task. J Orthop Sports Phys Ther 2016; 46:277–285. doi:10.2519/jospt.2016.6132.
6. DeJong AF, Mangum LC, Hertel J. Ultrasound imaging of the gluteal muscles during the Y-balance test in individuals with and without chronic ankle instability. J Athl Train 2019; 55:49–57. doi:10.4085/1062-6050-363-18.
7. Mangum LC, Henderson K, Murray KP, Saliba SA. Ultrasound assessment of the transverse abdominis during functional movement: Transverse abdominis during movement. J Ultrasound Med 2018; 37:1225–1231. doi:10.1002/jum.14466.
8. DeJong AF, Mangum LC, Hertel J. Gluteus medius activity during gait is altered in individuals with chronic ankle instability: An ultrasound imaging study. Gait Posture 2019; 71:7–13. doi:10.1016/j.gaitpost.2019.04.007.
9. DeJong AF, Koldenhoven RM, Hart JM, Hertel J. Gluteus medius dysfunction in females with chronic ankle instability is consistent at different walking speeds. Clin Biomech (Bristol, Avon). 2020; 73:140–148. doi:10.1016/j.clinbiomech.2020.01.013.
10. Valera-Calero JA, Fernández-de-Las-Peñas C, Varol U, Ortega-Santiago R, Gallego-Sendarrubias GM, Arias-Buría JL. Ultrasound imaging as a visual biofeedback tool in rehabilitation: An updated systematic review. Int J Environ Res Public Health. 2021; 18(14):7554. doi:10.3390/ijerph18147554.

Alexandra F. DeJong Lempke, PhD, ATC, is a clinical assistant professor of Applied Exercise Science, co-director of the Michigan Performance Research Lab, and a member of the Exercise & Sport Science Initiative within the U-M School of Kinesiology.

Interested in reading more about MSK ultrasound? Check out these posts from the Scan:

• The Potential of Elastography in MSK Ultrasound
• The Role of Musculoskeletal Ultrasound in Sports Injuries
• Ultrasound-Guided Musculoskeletal Injections