Chronic exertional compartment syndrome: muscle changes with isometric exercise.
Chronic exertional compartment syndrome (CECS) is a well-documented cause of lower leg pain in active individuals. The pathophysiology is unclear, although it is generally believed to be associated with increased intramuscular pressure, but there is very little information about muscle function in relation to the onset of pain.


OBJECTIVE
To investigate strength, fatigue, and recovery of the anterior tibial muscles in CECS patients and healthy subjects during an isometric exercise protocol.


METHODS
Twenty patients and 22 control subjects (mean age 27.6 yr and 33.0 yr, respectively) performed a 20-min isometric exercise protocol consisting of intermittent maximal voluntary contractions (MVC). Central fatigue was evaluated by comparing changes in electrically stimulated (2 s at 50 Hz) and voluntary contraction force before and during the exercise, and then throughout 10 min of recovery. Muscle size was measured by ultrasonography. Pain and cardiovascular parameters were also examined.


RESULTS
The absolute MVC forces were similar, but MVC:body mass of the patients was lower (P < 0.05) as was the ratio of MVC to muscle cross-sectional area (P < 0.01). The extent of central and peripheral fatigue was similar in the two groups. The patients reported significantly higher levels of pain during exercise (P < 0.05 at 4 min) and after the first minute of recovery (P < 0.001). An 8% increase in muscle size after exercise was observed for both groups. There were no differences in the cardiovascular responses of the two groups.


CONCLUSIONS
CECS patients were somewhat weaker than normal but fatigued at a similar rate during isometric exercise. Patients reported higher pain than controls despite comparable changes in muscle size, suggesting that abnormally tight fascia are not the main cause of CECS symptoms.
Birtles
Deirdre B
DB
Applied Biomedical Research Group, GKT School of Biomedical Sciences, King's College London, Shepherd's House, Guy's Campus, London SE1 1UL, UK.
Minden
David
D
Wickes
Simon J
SJ
M  Puxley
Ken P
KP
A  Llewellyn
Michael G
MG
Casey
Anna
A
Rayson
Mark P
MP
Jones
David A
DA
Newham
Di J
DJ
D000328:Adult; D000868:Anterior Compartment Syndrome / Q000150:complications / Q000503:physiopathology*; D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D002908:Chronic Disease; D003971:Diastole / Q000502:physiology; D015444:Exercise / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology; D010146:Pain / Q000150:complications / Q000503:physiopathology; D010147:Pain Measurement; D005082:Physical Exertion / Q000502:physiology*; D010812:Physical Stimulation; D020127:Recovery of Function / Q000502:physiology; D012146:Rest / Q000502:physiology; D013599:Systole / Q000502:physiology; D006113:United Kingdom