Bone Scanning for Detection of Exercise-Induced Musculoskeletal Injury.

Area of Science:

• Sports Medicine
• Exercise Physiology
• Biomedical Imaging

Background:

• Endurance running, particularly ultramarathons like the Western States 100-Mile Endurance Run, places extreme stress on the musculoskeletal system.
• Understanding the extent and time course of exercise-induced muscle damage (EIMD) is crucial for athlete recovery and performance.
• Previous research has explored biochemical markers, but imaging techniques offer direct visualization of tissue changes.

Purpose of the Study:

• To quantify muscle and bone damage in participants of a 100-mile endurance run using bone scintigraphy.
• To correlate imaging findings with subjective reports of muscle pain and biochemical markers of muscle injury.
• To assess the temporal resolution of these imaging findings post-race.

Main Methods:

• Bone scans (scintigraphy) were performed on 37 runners 24 hours to one week after the race.
• Laboratory tests included enzyme analyses (creatine kinase - CK, CK MB).
• Muscle biopsy specimens were analyzed for histological changes.

Main Results:

• Increased tracer uptake in specific muscle regions correlated with reported muscle pain.
• The intensity of tracer concentration was generally proportional to the severity of pain experienced.
• Muscle tracer uptake diminished significantly by one week post-race, with no abnormalities detected.
• Elevated levels of total CK and CK MB were observed.
• Muscle biopsies revealed myofibrillar lysis and mitochondrial damage.

Conclusions:

• Bone scintigraphy can detect and localize muscle damage in ultramarathon runners.
• The imaging findings support the biochemical and histological evidence of significant exercise-induced muscle damage.
• The transient nature of tracer uptake suggests a recovery process within one week for most observed muscle alterations.