Expression of the stress proteins, ubiquitin, heat shock protein 72, and myofibrillar protein content after 12 weeks of leg cycling in persons with spinal cord injury.
OBJECTIVE
To determine the effects of leg cycling exercise on ubiquitin (UBI), heat shock protein 72 (HSP-72) mRNA, protein expression, and myofibrillar protein content in individuals with spinal cord injury (SCI).


METHODS
Case series.


METHODS
Motor behavior laboratory.


METHODS
Seven subjects with motor-complete SCI (4 men, 3 women).


METHODS
A 12-week exercise program involving an electromagnetically braked recumbent bicycle ergometer, which allowed for passive exercise of the legs. Training occurred 2 days a week at approximately 75% of each subject's maximum heart rate.


METHODS
Total body mass (TBM) and muscle biopsies were obtained pre- and posttraining. The mRNA and protein expression of UBI, HSP-72, and myofibrillar protein content were determined.


RESULTS
Nonsignificant increases (P > .05) of 2.45% were observed for TBM. There were significant increases (P < .05) in the expression of both HSP-72 mRNA (33.71%) and protein (30.23%). For UBI, there were also significant decreases (P < .05) in the expression of both mRNA (26.86%) and protein (69.43%). Myofibrillar protein content increased significantly (P < .05, 41.86%).


CONCLUSIONS
Leg cycling exercise in SCI increases myofibrillar protein content, possibly because of up-regulation in the expression of HSP-72 with concomitant down-regulation in the expression of UBI.
Willoughby
Darryn S
DS
Department of Kinesiology, Texas Christian University, Fort Worth, TX 76129, USA. d.willoughby@tcu.edu
Priest
Joe W
JW
Nelson
Matt
M
D000293:Adolescent; D000328:Adult; D001642:Bicycling / Q000502:physiology*; D005081:Exercise Therapy; D005260:Female; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000032:analysis* / Q000235:genetics; D006801:Humans; D007866:Leg / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D009124:Muscle Proteins / Q000032:analysis* / Q000235:genetics; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology; D009210:Myofibrils / Q000235:genetics / Q000473:pathology / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis* / Q000235:genetics; D013119:Spinal Cord Injuries / Q000473:pathology / Q000503:physiopathology* / Q000534:rehabilitation*; D013997:Time Factors; D025801:Ubiquitin / Q000032:analysis* / Q000235:genetics
D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D009124:Muscle Proteins; D012333:RNA, Messenger; D025801:Ubiquitin