Exercise-induced rib stress fractures: potential risk factors related to thoracic muscle co-contraction and movement pattern

TY - JOUR

T1 - Exercise-induced rib stress fractures: potential risk factors related to thoracic muscle co-contraction and movement pattern

AU - Vinther-Knudsen, Archibald

AU - Kanstrup, I-L

AU - Christiansen, E

AU - Alkjaer, T

AU - Larsson, B

AU - Magnusson, S P

AU - Ekdahl, C

AU - Aagaard, P

PY - 2006

Y1 - 2006

N2 - The etiology of exercise-induced rib stress fractures (RSFs) in elite rowers is unclear. The purpose of the study was to investigate thoracic muscle activity, movement patterns and muscle strength in elite rowers. Electromyographic (EMG) and 2-D video analysis were performed during ergometer rowing, and isokinetic muscle strength was measured in seven national team rowers with a history of RSF and seven matched controls (C). RSF displayed a higher velocity of the seat in the initial drive phase (RSF: 0.25+/-0.03, 0.25 (0.15-0.33) m/s vs C: 0.15+/-0.06, 0.18 (-0.11-0.29) m/s P=0.028) (Mean+/-SEM, median and range). Further, RSF had greater co-contraction of m. serratus anterior and m. trapezius in the mid-drive phase (RSF: 47.5+/-3.4, 48.5 (35.8-60.2)% EMG signal overlap vs C: 30.8+/-6.5, 27.0 (11.2-61.6)%P=0.043). In addition, the RSF subjects showed a lower knee-extension to elbow-flexion strength ratio (RSF: 4.2+/-0.22, 4.3 (3.5-5.1) vs C: 4.8+/-0.16, 5.0 (4.2-5.3) P=0.043), indicating stronger arms relative to legs compared with controls. In conclusion, increased thoracic muscle co-contraction, altered movement patterns and reduced leg/arm strength ratio were observed in the RSF subjects, which may all predispose toward an increased risk of RSF.

AB - The etiology of exercise-induced rib stress fractures (RSFs) in elite rowers is unclear. The purpose of the study was to investigate thoracic muscle activity, movement patterns and muscle strength in elite rowers. Electromyographic (EMG) and 2-D video analysis were performed during ergometer rowing, and isokinetic muscle strength was measured in seven national team rowers with a history of RSF and seven matched controls (C). RSF displayed a higher velocity of the seat in the initial drive phase (RSF: 0.25+/-0.03, 0.25 (0.15-0.33) m/s vs C: 0.15+/-0.06, 0.18 (-0.11-0.29) m/s P=0.028) (Mean+/-SEM, median and range). Further, RSF had greater co-contraction of m. serratus anterior and m. trapezius in the mid-drive phase (RSF: 47.5+/-3.4, 48.5 (35.8-60.2)% EMG signal overlap vs C: 30.8+/-6.5, 27.0 (11.2-61.6)%P=0.043). In addition, the RSF subjects showed a lower knee-extension to elbow-flexion strength ratio (RSF: 4.2+/-0.22, 4.3 (3.5-5.1) vs C: 4.8+/-0.16, 5.0 (4.2-5.3) P=0.043), indicating stronger arms relative to legs compared with controls. In conclusion, increased thoracic muscle co-contraction, altered movement patterns and reduced leg/arm strength ratio were observed in the RSF subjects, which may all predispose toward an increased risk of RSF.

KW - Adult

KW - Athletic Injuries

KW - Case-Control Studies

KW - Disease Susceptibility

KW - Elbow Joint

KW - Electromyography

KW - Ergometry

KW - Female

KW - Fractures, Stress

KW - Humans

KW - Knee Joint

KW - Lower Extremity

KW - Male

KW - Motor Activity

KW - Movement

KW - Muscle Contraction

KW - Muscle, Skeletal

KW - Rib Fractures

KW - Risk Factors

KW - Thorax

KW - Upper Extremity

KW - Video Recording

U2 - 10.1111/j.1600-0838.2005.00473.x

DO - 10.1111/j.1600-0838.2005.00473.x

M3 - Journal article

C2 - 16643197

SN - 0905-7188

VL - 16

SP - 188

EP - 196

JO - Scandinavian Journal of Medicine & Science in Sports

JF - Scandinavian Journal of Medicine & Science in Sports

IS - 3

ER -