The effects of leg crossing and applied tension on blood donor return

Abstract

Repeated isometric muscle tension (applied tension) during blood donation reduces vasovagal symptoms in many donors. Experiencing vasovagal symptoms has been found to reduce blood donor return. However, does practicing applied tension improve blood donor return? Follow-up results from a randomized controlled trial are presented. Data were collected in mobile clinics held in several colleges and universities. During the baseline donation, participants either (1) practiced 'standard' applied tension consisting of repeated 5s cycles of whole-body isometric muscle tension in the donation chair (N=133), (2) practiced tension with legs crossed (N=131), or (3) gave blood as usual (N=140). Subsequent blood donations in the following 2years were determined. Applied tension had no effect on immediate (at the end of the baseline blood donation) rating of intention to give blood or the dichotomous measure of whether or not the participant gave blood again in the following 2years. However, men asked to practice applied tension with legs crossed gave approximately one unit more during the follow-up period compared with men in the control group (F1,106 =5·32, P=0·023). This was associated significantly with adherence - men assigned to the applied tension with legs crossed condition who did not practice as instructed were no more likely to return than controls. The results provide modest support for the idea that applied tension may increase subsequent blood donation though the results were limited to men who practiced the technique as instructed.