Focal knee joint cooling increases the quadriceps central activation ratio

• Published in: Journal of sports sciences 2009-06, Vol.27 (8), p.873-879
• Main Authors: Pietrosimone, Brian G., Ingersoll, Christopher D.
• Format: Article
• Language: English
• Subjects: Adult; Biological and medical sciences; Cold Temperature; Comparative analysis; Cross-Over Studies; cryotherapy; Effects; Female; Fundamental and applied biological sciences. Psychology; Humans; Ice; Intervention; isometric contraction; Knee; Knee Joint - physiology; Male; motor neurons; Muscle Contraction - physiology; Quadriceps muscle; Quadriceps Muscle - physiology; Studies; Time Factors; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports; Volition; Young Adult
• ISSN: 0264-0414; 1466-447X
• DOI: 10.1080/02640410902929374

The objective of this study was to evaluate the effects of a 20-min focal knee joint cooling intervention on quadriceps central activation ratio (CAR) in healthy volunteers. A counterbalanced, cross-over study assessed the effects of a focal joint cooling intervention compared with a control condition 3-14 days apart. Eleven healthy volunteers (6 males, 5 females; age 25 ± 5 years; height 1.71 ± 0.1 m, mass 77 ± 21 kg) were included in the final analysis. The joint cooling intervention consisted of two 1.5-litre ice bags applied to the knee joint for 20 min, in one of two counterbalanced sessions, completed 3-14 days apart. In the control session, participants sat quietly between the baseline and 20-min measurements. Quadriceps CAR was assessed at 70° of knee flexion at four instants (baseline, 20, 30, and 45 min). There was a significant treatment × time interaction (F 3,30  = 5.9, P = 0.003) and post hoc analyses revealed that CAR was higher in the focal knee joint cooling session than the control session at 20 min (0.79 ± 0.12 vs. 0.70 ± 0.12; t 10  = 3.9, P = 0.003) and 45 min (0.77 ± 0.10 vs. 0.69 ± 0.12; t 10  = 3.1, P = 0.01). The CAR tended to be higher during the experimental session than the control session at 30 min (0.79 ± 0.13 vs. 0.74 ± 0.11; t 10  = 2.1, P = 0.07).Volitional activation increased following focal knee joint cooling in healthy volunteers.