Figure 3From: The relative timing of VMO and VL in the aetiology of anterior knee pain: a systematic review and meta-analysis Results from four studies that measured onset timing of the VMO and VL during different activities. A negative VMO-VL value indicates VMO activation before VL activation. 2. Standard deviation for the study by Earl et al [17] is an estimate based on data from other studies. 3. Results from individual studies are not quantitatively combined since the onset timing was measured during different tasks.Back to article page