Global Journal of Medical Research, K: Interdisciplinary, Volume 22 Issue 4

designed backpack than the regular backpack 20 . Another study was conducted by Motmans et al., on 19 participants on different modes of bag carriage, as a backpack, front pack, shoulder bag and double pack. Electromyogram (EEG) readings of rectus abdominis and spinae erector were observed during each mode of carriage twice, once with no load and with 15% load of body weight of the individual. The results showed a significant decrease in load carriage as a backpack but increased when it was carried as a shoulder bag and front pack. Rectus abdominis showed increased activation during backpack mode of carriage. There was a significant asymmetry in back and abdominal muscles during shoulder carriage. The study also suggested that asymmetrical load carriage might cause a decrease in trunk stability which might lead to back pain 21 . b. Fatigue in ocular muscles Overall fatigue can also be seen in the ocular muscles 22 . Critical Flicker Fusion Frequency (CFFF) is used to measure the ocular fatigue which representative of overall fatigue 7 . Eye conditions can affect scholastic performance by not only reducing concentration but also by interfering with the ability to read, learn and play 23 . A recent study conducted among school children in Karnataka, India implied higher CFFF thresholds to improve cognition and boost academic performance 24 . Reports regarding schoolbag carriage and its effect on CFFF weren’t observed after extensive literature search highlighting the lacunae with respect to exploring this particular physical activity. The practice of carrying heavy backpacks is common, indicating high intensity physical activity manifesting fatigue which may be reflected in ocular muscles. Vision in children is an important aspect within the school curriculum and CFFF alterations due to schoolbag carriage must be explored. Apart from fatigue, perspiration and thirst are also characteristic of physical activity 25 . 2. Physical Activity and Thirst The relationship between physical activity and hydration is extremely important in our day to day activities as hydration status dictates the overall equilibrium of our body 26 . In 1994, Meyer et al., pointed out that the mild hypo-hydration occurring among children who exercised in the heat had a greater degree of induced thirst and most children drank more fluid than they lost during the exercise session 27 . Mears et al., in 2016 reported the development of thirst sensation after exercise and its persistence until voluntary water intake among young adults 28 . Young adults in hypo- hydrated state were also reported to have consumed more than 55% of total fluid loss that manifested in them during the exercise period 29 . The effect of physical activity on subjective urge to drink water has been heavily documented 30 but thirst alterations and hydration status in schoolchildren due to the physical activity of schoolbag carriage remains unexplored. 3. Physical Activity and Saliva Viscosity Dawes et al., studied on the effect of physical activity on saliva viscosity. The results revealed increased viscosity and protein content in the saliva immediately post- physical activity 34 . A similar study was conducted by G.Ljungberget al., on the participants of the Stockholm Marathon in 1990, suggested increased concentration and total protein content in the saliva after running the marathon (Ljungberg et al., 1997). A relatively recent study in 2015 suggested a temporary increase in saliva viscosity right after moderate intensity physical activity 35 . This finding was bolstered by a study in the following year by Ligtenberg et al., validating increased saliva viscosity during and after exercise among the participants 36 . This aspect of physical activity remains unexplored for schoolbag carriage as indicated by a thorough literature search. Schoolbag carriage being a physical activity, causes alterations in parasympathetic and sympathetic activity, termed as the Central Command 37 . Physical activity stimulates the sympathetic nervous system, which controls salivary protein secretion by the alpha and the beta adrenergic neurons via the Superior Cervical Ganglion 38 . Whereas, parasympathetic activity is seen to decrease with the increase in heart rate 39 . On cessation of physical activity, the heart rate goes back to normal and the parasympathetic system is reactivated 40,41 . As the water flux or the salivary water content is dependent on the parasympathetic nervous system, changes in the salivary flow rate due to schoolbag carriage might be observed and remains to be documented. The consequent change in salivary density, protein concentration change due to the stimulation of the sympathetic and parasympathetic system due to schoolbag carriage also remains to be documented. The dehydrated state and workload alters the cognitive and motor performance 42 . Saliva viscosity can also influence cognitive and motor performance 43 . 4. Physical Activity and Neurological Performance The main aspects of neurological performance considered in case of children related to the topic are- cognitive and motor ability. While cognitive functions mainly deal with logical reasoning, motor ability deals with physical abilities. Physical activity also influences both cognitive and motor functions. 3 Year 2022 Global Journal of Medical Research Volume XXII Issue IV Version I ( D ) K © 2022 Global Journals Investigating the Facets of Physical Activity Related to Schoolbag Carriage- Highlighting the Lacunae that Exists Given that thirst induces physiological changes 31 and decreased dehydration bolsters cognition directly affecting academic performance in children 32 , this becomes a very important area to delve into. Thirst is primarily accompanied with the change in the saliva concentration. Saliva Viscosity is can be used to measure the physiological thirst 33 .