4.1. Reduction in blood flow rate when subjects wore a backpack
After wearing backpack for 8 minutes, the time-averaged mean blood velocity and the blood flow rate are observed to be significantly altered. By comparing the result to the pressure sensor recordings, this may be contributed by the direct mechanical compression of the backpack strap on the shoulders, along with the vessels including axillary vein lying beneath [7]. The luminal diameter of the vessels reduces by the compression because of its nature of low blood pressure and minimal vessel wall elasticity. This temporary venous stasis may lead to the alteration in brachial artery haemodynamics [7]. By Poiseuille’s Equation, the resistance in blood vessel (R) is directly …show more content…
Reduction of blood flow rate comparing right and left arm when wearing a backpack
The blood flow rate of brachial artery was found to be decreased significantly after the subjects carried the backpack for 8 minutes. Slightly more reduction in blood flow rate was recorded in the right arm than the left after wearing the backpack. However, as shown by the independent sample test, there was no overall significance in the difference among left and right arm concerning this finding. In addition, the recordings from the pressure sensor showed the pressure exerted on the shoulders by the compression of the backpack straps were similar from both sides.
According to the findings from section 4.1, equal pressure on both shoulders means equal reduction of blood flow rate on both sides. Pressure exerted is theoretically identical on both shoulders. The finding matches the hypothesis that the backpack was carried in a symmetric manner when subjects were standing naturally. This shows an equal distribution of burden shared among two shoulders if the user wears a backpack with an upright …show more content…
This study validates the influence of haemodynamic alteration under the flexion. A previous study suggests wearers may undergo unaware thoracic lateral flexion when the weight of the backpack is excessive and exerted asymmetrically [14]. Potential of accidental injury increases when wearers undergo the flexion intentionally or unintentionally to overcome the loading of the backpack. The decrease in blood flow rate may also induce temporary or chronic neurological and musculoskeletal deficits in upper extremities [4][7][9][15]. Schoolchildren are more prone to suffer from spinal deformities especially in cervical and lumbar region