Standard leg shape is the judging principle of beautiful legs, which involves leg length, leg-to-body ratio, thigh circumference, thigh length, calf length and other factors.

The narrow sense of leg length and true leg length is scientifically called full leg length [1], but it is difficult to measure. In academic circles, height minus sitting height is generally used to represent leg length. Mahalanobis trunk leg length index = [(height-sitting height)/sitting height ]× 100, which is the most reliable and valuable quantitative index for discussing leg-to-body ratio [2], laying a foundation for studying leg-to-body ratio.

Leg length is expressed by hip height or height MINUS sitting height: at the same height, female legs are longer than male legs; However, because the leg-to-body ratio is positively correlated with height, the greater the height, the greater the leg-to-body ratio; Therefore, the average and extreme values of leg-to-body ratio and Mahalanobis trunk leg length index are slightly higher for men than for women [3][4].

Whether the knee is over the shoulder [5][6], whether the wrist line is over the hip line [7][8] and whether the wrist line is over the perineum can be roughly judged except that the horse is held high above the head.

The thigh circumference is the horizontal circumference of the thigh passing through the hip and thigh groove, which is also called the maximum circumference of the thigh, not the middle circumference of the thigh [1]. Height and thigh circumference index = (thigh circumference/height) × 100, thigh length index = (thigh circumference/thigh length) ×100; These two indexes are higher for women than for men, with significant differences; That is to say, women's legs are relatively thick and short, while men are relatively slender [9] [10]; This is related to the gender difference in body fat distribution [1 1]. Estrogen inhibits abdominal fat accumulation and increases hip and thigh fat accumulation, while androgen is just the opposite [12].

The length of thigh is the length of femur, which is the thickest and longest bone in human body [13]. There are two long bones in the calf, namely tibia and fibula. Usually, the length of the calf refers to the length of the tibia [1], and also refers to the length of the fibula [14]. The femur of China people is 7- 10cm longer than the tibia. Only the length of tibia plus the height of foot (that is, the height of tibial point) can approach or exceed the length of femur [15]. However, the human average (tibia length/femur length) × 100 is only over 80 [16]. Central index = (calf length/thigh length) × 100, and people with high index are more suitable for jumping [17]. Short thighs and long calves are called antelope legs [18].