Effects of ankle pump exercise frequency on venous hemodynamics of the lower limb

The purpose of this study was (1) to compare the effects of ankle pump exercise(APE) frequency on hemodynamics of the common femoral vein(CFV) and (2) to analyse the relationship between APE duration and lower limb fatigue.Twenty-seven males and thirty-three females performed APE. Among them, there were thirty participants with non-lower limb fracture (N-LLF) and thirty participants with lower limb fracture (LLF).The colour doppler ultrasound was used to record the time-averaged mean velocity (TAMV) of common femoral venous flow when the participants at rest and move at different frequencies of 6 times/min, 10 times/min, 30 times/min, 60 times/min. The ratings of perceived exertion (RPE) was used to assess the lower limb fatigue of the participants when performing APE at the frequency of 60 times/min after 1 min, 2 mins, 3 mins, 4 mins and 5 mins.With the increase of frequency, TAMV increased significantly in both the participants with N-LLF and LLF (p < 0.01). The TAMV were 19.82±3.86, 33.78±8.76, 37.06±8.67, 43.82±10.40, 52.18±10.53, respectively in the participants with N-LLF and 16.98±3.01, 22.20±4.96, 24.01±5.78, 29.20±7.05, 35.75±9.28, respectively in the injured limb of patients with LLF when at rest and moving at the frequency of 6 times/min, 10 times/min, 30 times/min, 60 times/min. There was a positive correlation (p < 0.01) between lower limb fatigue and exercise duration.When the RPE was 16 points (the corresponding fatigue degree is "tired"), the exercise duration of the participants with N-LLF was 3 mins and that of the injured limb of patients with LLF was 2 mins.Both fast and slow-frequency APE can promote venous blood return in the lower limb. Despite of the equivalent APE duration, fast-frequency APE can promote venous blood return more effectively. When the frequency of APE was 60 times/min, participants with N-LLF can exercise for 3 mins, and the injured limb of patients with LLF can exercise for 2 mins.