Discussion
A highly significant increase in temperature, heart rate, pulse rate and respiration rate were observed after exercise when compared to before exercise. An increased heart rate and respiration rate in the present study is in concurrence with Snow and Mackenzie (1977); Katz et al. (2000); Hassan et al. (2015). The elevated heart rate and respiration rate following exercise may be attributed to the activation of the sympathetic nervous system and the subsequent rise in catecholamine levels. An increase in rectal temperature in the present study is in accordance with Gisolfi (2001) and Hassan et al. (2015). It is mainly due to continues muscular contractions that needs a continuous energy supply derived from fat metabolism and the energy obtained through the breakdown of ATP molecules typically serves to maintain body temperature (Fritzsche and Coyle, 2000; McKeever and Kearns, 2001) and it may also be due to compromised cardiovascular, respiratory and heat loss mechanism (Malinowski et al ., 1993).
After exercise there was a highly significant increase in Hb, RBC and PCV and significant increase in MCV when compared to pre-exercise. Similar findings were also reported by Andrews et al. (1995), Thompson et al. (2001), Ricketts (2004) and Hassan et al. (2015). This increase in hematological parameters might be attributed to the release of splenic erythrocytes influenced by catecholamines during exercise and hemoconcentration resulting from dehydration, as suggested by Ricketts (2004).
In the present study there was a highly significant increase in WBC and lymphocytes after exercise when compared to before exercise. This result was in accordance with Rose and Hodgson (1982); Snow et al. (1983); Hassan et al. (2015). The exercise-induced leukocytosis is likely attributed to catecholamine. The spleen not only releases stored erythrocytes but also releases leukocytes into the peripheral circulation. The spleen plays a crucial role as a production site, especially for lymphocytes. Consequently, the increase in leukocytes in the peripheral circulation is predominantly comprised of lymphocytes than other type of leukocytes.
In the present study there was a significant decrease in platelet count and highly significant increase in MPV after exercise when compared to before exercise. These findings are in accordance with Zobba et al. (2011). Mild exercise tends to have minimal effects on platelet activation and may even dampen it, while strenuous exercise causes increase in platelet activation which depends on intensity of exercise (Wang et al., 1994).
In this study, highly significant elevation of glucose was observed after exercise when compared to before exercise. These findings were agreed with Nakata et al. (1999), Simões et al. (1999) and Hassan et al. (2015). These increases in glucose levels might be attributed to the hyperactivity of the sympathetic nervous system and the release of adrenaline, which, trigger hepatic glycogenolysis (Trilket al ., 2002).
The values of total protein and albumin showed highly significant increase after exercise when compared to before exercise. This was in accordance with the findings of Sommardahl et al. (1994); Zobbaet al. (2011) and Hassan et al. (2015). They reported that redistribution of fluid and electrolytes from the vascular compartment to the extra-cellular fluid spaces within the tissues, along with a decrease in plasma volume resulting from removal of fluid from bloodstream, leading to hemoconcentration and dehydration.
Highly significant increase in cholesterol after exercise was documented when compared to before exercise. This finding was in accordance with Hassan et al. (2015). The rise in cholesterol concentration could be due to lipid mobilization resulting from intensive physical activity.
Aspartate transaminase (AST) showed highly significant increase after exercise when compared to before exercise. These findings were consistent with Kobluk et al. (1995) and Hassan et al. (2015). The rise in AST levels could be attributed to the increased permeability of enzyme from muscle cell caused by muscular stress (Watson, 1998). Alkaline phosphatase (ALP) showed highly significant increase after exercise when compared to before exercise. These findings are consistent with Rose et al. (1980). He found that the rise in ALP after exercise was unclear whether the source was skeletal or hepatic.
In this study elevated levels of lactate dehydrogenase were observed after exercise when compared with before exercise. This is in accordance with Tateo et al. (2008) and Hassan et al. (2015). They observed that the release of LDH from tissues after exercise and it has been mostly from muscles. In this study triglycerides showed significant increase after exercise when compared to before exercise. These results are similar with Rose et al. (1980). This increase might be attributed to the rapid increase of free fatty acid concentration in the bloodstream. Horse liver possesses a considerable ability to convert FFA into triglycerides (Pösö et al., 1983) and consequently, the rate of triglyceride synthesis is influenced by the availability of FFA.
Creatinine and Blood urea nitrogen (BUN) showed highly significant increase after exercise when compared to before exercise. These findings are in accordance with Pringle (1995). These increases might be attributed to extensive fluid loss in the sweat, the reduction in renal blood flow and glomerular filtration rate that leads to elevation of urea concentration after exercise as quoted by Piccione et al. (2010). Härtlová et al. (2010) suggested that the increased level of creatinine might be due to release of creatinine from working muscles.
In this study, calcium and magnesium showed significant decrease after exercise when compared to before exercise. This result was similar to that reported by Schryver et al. (1978) and Hassan et al. (2015). The decline in calcium levels could potentially be attributed to the persistent action of calcitonin, which might decrease the serum Ca concentration. In addition to that the decline in serum calcium concentration in exercising horses could be attributed to the loss of calcium through sweat during exercise.Top of Form
The reduction in magnesium levels following exercise might be attributed to the loss of magnesium through sweat (Weiss et al., 2002).
In this study, phosphorous showed highly significant increase after exercise when compared to before exercise. This was in accordance with Hassan et al. (2015) who reported this change to the release of phosphate from muscles during the breakdown of high-energy phosphate (ATP) during exercise.
In our study there was a highly significant increase in sodium after exercise when compared to before exercise. This finding was in accordance with Hassan et al . (2015) and Prado et al. (2019). They reported that the release of aldosterone due to dehydration after exercise which results in the resorption of sodium into bloodstream.
In our study there was a significant increase in potassium after exercise when compared to before exercise. There was a similar finding reported by Harris and Snow (1986); Hassan et al. (2015) and Prado et al. (2019). The K+ ion is the predominant cation present within the cells, with its concentration in the extracellular space being low due to the activity of the Na+/K+-ATPase pump, which expels three Na+ ions from the cell in exchange for two K+ ions. Approximately 98% of the total body K+ ions are stored intracellularly, primarily in muscle tissue (Terker et al., 2015). Reduction in H2O muscle, K+ ions exit muscle cells and enter the bloodstream, leading to an increase in their concentration as reported by Prado et al. (2019).
In our study there was a significant decrease in chloride after exercise when compared to before exercise. These findings were consistent with Mckeever (2002), Hassan et al. (2015) and Prado et al. (2019). The decrease in the concentration of chloride after exercise is due to significant loss of chloride ion in the sweating with a subsequent reduction in blood serum (Demirtaş et al., 2015).