This one is supportive of keeping the leg warm; but note the methodology - the leg is brought to full stop - no exercise - then iced - and then the impact on physical ability is assessed. Our question is DURING the exercise, does the knee need additional protection to be kept warm, and at what temperature is this true. So this says, "cold is bad" but doesnt answer er to say it stupidly, whether a cyclists knee is cold. Contrasting an inactive knee that is getting iced - to an active knee that is being kept warm by constant muscle activity - isnt a comparison.
Again, with the same conclusion - if you get cold - you will suffer performance degradationJ Electromyogr Kinesiol. 2010 Dec;20(6):1075-81. Epub 2010 Aug 10.
Effect of knee joint cooling on the electromyographic activity of lower extremity muscles during a plyometric exercise.
Schmid S, Moffat M, Gutierrez GM.
Bern University of Applied Sciences, Health Division, Research and Development Physiotherapy, Murtenstrasse 10, 3008 Bern, Switzerland. firstname.lastname@example.org
During sporting events, injured athletes often return to competition after icing because of the reduction in pain. Although some controversy exists, several studies suggest that cryotherapy causes a decrease in muscle activity, which may lead to a higher risk of injury upon return to play. The purpose of this study was to investigate the effect of a 20-min knee joint cryotherapy application on the electromyographic activity of leg muscles during a single-leg drop jump in twenty healthy subjects, randomly assigned to an experimental and a control group. After the pre-tests, a crushed-ice bag was applied to the knee joint of the experimental group subjects for 20 min, while the control group subjects rested for 20 min. All subjects were retested immediately after this period and retested again after another 20 min of rest. Average electromyographic activity and ground contact time were calculated for the pre- and post-test sessions. Decreases in electromyographic activity of the lower extremity musculature were found in pre-activation, eccentric (braking), and concentric (push-off) phases immediately after the icing, and after 20 min of rest. The results lend support to the suggestion that cryotherapy during sporting events may place the individuals in a vulnerable position.
SameRes Q Exerc Sport. 2010 Jun;81(2):127-32.
Changes in landing mechanics after cold-water immersion.
Wang H, Toner MM, Lemonda TJ, Zohar M.
School of Physical Education, Sport, and Exercise Science at Ball State University, Muncie, IN 47306, USA. email@example.com
The purpose of this study was to investigate the influence of cold-water immersion on kinematics and kinetics during a drop-landing task. On four separate occasions, 9 men performed drop-landings from a 0.6-m platform to a force platform following 30-min immersion to the hip-joint in thermoneutral water (control; 34 degrees C) and in cold water (20 degrees C) to the ankle (low level), knee (medium level), and hip (high level) joints. Sagittal plane kinematics and kinetics were determined. One-way repeated measures multivariate analysis of variance was used for statistical analysis. Compared to the control, the low-level condition had similar joint mechanics, the medium level showed 26% less ankle mechanical work (p = .003), and the high level showed 9% less vertical ground reaction force (p = .025) and 23% less ankle mechanical work (p = .023) with 18% greater trunk flexion (p = .024). In summary, the low-level cold-water immersion had no effect on landing mechanics. The medium- and high-level cold-water immersion resulted in a reduction in impact absorption at the ankle joint during landing. The increased trunk flexion after high-level immersion helped dissipate landing impact.
I am going to look at some more - but so far these are all saying dont exercise AFTER you have iced your knees. Get warm and stay warm.Int J Sports Med. 2010 Mar;31(3):198-201. Epub 2009 Dec 17.
Cryotherapy impairs knee joint position sense.
Oliveira R, Ribeiro F, Oliveira J.
Jean Piaget Institute, Health School of Vila Nova de Gaia, Vila Nova de Gaia, Portugal. firstname.lastname@example.org
The effects of cryotherapy on joint position sense are not clearly established; however it is paramount to understand its impact on peripheral feedback to ascertain the safety of using ice therapy before resuming exercise on sports or rehabilitation settings. Thus, the aim of the present study was to determine the effects of cryotherapy, when applied over the quadriceps and over the knee joint, on knee position sense. This within-subjects repeated-measures study encompassed fifteen subjects. Knee position sense was measured by open kinetic chain technique and active positioning at baseline and after cryotherapy application. Knee angles were determined by computer analysis of the videotape images. Twenty-minute ice bag application was applied randomly, in two sessions 48 h apart, over the quadriceps and the knee joint. The main effect for cryotherapy application was significant (F (1.14)=7.7, p=0.015) indicating an increase in both absolute and relative angular errors after the application. There was no significant main effect for the location of cryotherapy application, indicating no differences between the application over the quadriceps and the knee joint. In conclusion, cryotherapy impairs knee joint position sense in normal knees. This deleterious effect is similar when cryotherapy is applied over the quadriceps or the knee joint.
Georg Thieme Verlag KG Stuttgart.New York.
Again, our question is whether exercising in cold weather, assuming a sufficient warm up, assuming the flesh is warm - is that a problem.