Kneeling-induced calf ischemia: a pilot study in apparently healthy European young subjects.

PURPOSE: Many tasks, sports or leisure activities require maximal knee flexion. We hypothesized that this position could result in reduced calf perfusion, in young European subjects. METHODS: We quantified calf ischemia resulting from the knee flexion with transcutaneous oxygen pressure (TcpO2) sensors by assessing the decrease from rest of TcpO2 (DROP) defined as limb changes minus chest changes. A minimal DROP (DROPm) <-15 mmHg defines the presence of ischemia. From the crawling position, participants kneeled for 3 min while bending as in prostration/prayer position (P). Thirty-five participants repeated this maneuver a second time, while 7 participants were also required to sit on their heels with the torso in the vertical position to attain knee flexion without significant groin flexion (S). RESULT: In 41 healthy young volunteers (30 males), 25 [20-31] years old, 37 patients showed a DROPm < -15 mmHg from "R" to "P" in one (n = 4) or both (n = 33) calves (90.2%; 95% CI 76.9-97.3). After backward regression of the DROPm, there was no significant association with side, body weight of systolic blood pressure. However, age was strongly associated with DROPm (OR 5.34 [2.45-8.69]) so that DROPm was significantly higher in older, with a correlation ρ = 0.31 (p = 0.003). CONCLUSION: Kneeling dramatically reduces calf perfusion, likely through popliteal artery kinking, possibly through muscle crushing. Eastern lifestyle includes routine flexed position since childhood. Whether or not such a chronic training reduces the risk of kneeling-induced ischemia in adults is unknown to date.