Ultrasound evaluation of joint and bursal fluid changes after a 5-km run in healthy adults.

Abstract

Background: Musculoskeletal ultrasound is widely used to assess joint and bursal effusions, yet the impact of moderate-distance running on fluid accumulation in asymptomatic individuals remains unclear. Previous studies have shown mixed results depending on exercise type and timing, highlighting a gap in understanding transient physiological responses to common physical activity such as running.

Objective: To determine whether a 5-km run induces detectable changes in fluid presence within selected joints and bursae in healthy adults, as assessed with musculoskeletal ultrasound.

Design: Prospective observational trial.

Setting: Institutional setting at a university hospital.

Participants: Thirty healthy adults (17 female, 13 male; ages 20-47 years) without musculoskeletal symptoms or recent injuries were recruited. All participants completed the study.

Interventions: Not applicable.

Main outcome measure(s): Binary (yes/no) presence of fluid in the tendon sheath of the long head of the biceps brachii, deep infrapatellar bursa, retrocalcaneal bursa, and talocrural joint were assessed bilaterally with ultrasound at baseline, immediately post run, and 24 hours post run.

Results: Significant increases in fluid were observed 24 hours post-run in the retrocalcaneal bursa (left: p < .001, g = 0.46; right: p < .001, g = 0.40) and talocrural joint (left: p = .001, g = 0.36; right: p = .002, g = 0.33). Long head of the biceps brachii showed transient changes (left: p = .002 next day). No significant changes were found in the deep infrapatellar bursa (all p > .05).

Conclusions: A short 5-km run can produce delayed increases in fluid at the ankle region, with the largest changes observed at 24 hours. Clinicians should account for recent physical activity when performing and interpreting ultrasound findings, as exercise may increase the prevalence of detectable fluid at certain sites. However, as the final assessment was performed at 24 hours, the full time course of these changes remains to be determined.