Method
Each of the two methods of cryotherapy, cold-jet stream (CS) and cold-jet stream combined with infrared therapy (CSCI), was applied to the medial aspect of 32 volunteers' knees. The first phase was the required time that skin was dropped to 10^oC with CS/CSCI. The second phase was the time for rewarming to 20^oC without CS/CSCI. The third phase was the required time that skin dropped to 10oC again with CS/CSCI. The fourth phase was the time for re-warming to 20^oC again without CS/CSCI.

Results
The required time which cold pain appeared after CS/CSCI were 51.3 sec and 62.3 sec, respectively, with significance (p＜0.01). In CS and CSCI, first phase was 71.6 sec and 90.7 sec, respectively, and third phase was 33.2 sec and 39.9 sec, respectively (p＜0.01). At second and fourth phases, it took 46.9 sec and 56.6 sec in CS (p＜0.01), and took 46.9 sec and 54.6 sec in CSCI (p＜0.01).

Conclusion
As compared with CS, CSCI delayed sensation time of cold pain and prolonged application time of CS at the knee. (J Korean Acad Rehab Med 2003; 27: 106-109)