Introduction
Physical exercise is a bodily activity that develops or maintains physical fitness and overall health.1 It is often practised to strengthen muscles and to optimise athletic skills. Exercise has multiple beneficial effects on the human body such as increasing threshold for pain, reducing high blood pressure and preventing obesity and heart disease.2–4 Regular exercise decreases the risk of certain cancers (prostate, lung, colon cancers) and improves cognitive functioning.3 It has been shown that exercise has a neuroprotective effect in many neurodegenerative and neuromuscular diseases.4–6 A previous study has also shown that exercise decreases anxiety and depression by increasing oxygen supply to the brain tissue and by increasing dopamine, serotonin, norepinephrine and acetylcholine.3 Exercise also promotes maximal hepatic glycogenolysis and gluconeogenesis by additive fall in insulin and rise in glucagon levels.
When challenged with any physical tasks, the human body responds through a series of integrated changes in function that involve most of its metabolically active organs (liver, kidney). The magnitude of these changes depends largely on the intensity and duration of the training sessions, force or load used in training and the body’s initial level of fitness.
It is well established that deliberate or accidental trauma to tissues can lead to abnormal enzyme activity in the plasma. Physical exercise, however, when strenuous or prolonged, has been shown to affect enzyme activities.1 Several studies have examined the changes in serum enzyme concentrations after sports activities. In one of such studies, after ultra-long distance running, the activities of plasma aspartate aminotransaminase (AST) and alanine aminotransaminase (ALT) were found to be elevated up to fivefold and threefold, respectively.2 Ahmad et al 7 investigated the effect of 8 weeks of endurance exercise activities on liver enzymes and observed that a long endurance activity results in a significant reduction in ALT and AST enzyme activities. However, in the study of Bijeh et al,8 AST and ALT levels after 8 weeks of swimming exercise were investigated among healthy women, and in that study, no significant changes were observed. While these findings seem encouraging, it is worthy of note that there are paucity of similar documented reports on men and women who engaged regularly on football sporting activity particularly among the Nigerian population, hence the need for this study.
Furthermore, it has been reported that after a moderate-intensity and high-intensity exercise, there is a decrease in urine volume and a marked reduction in renal plasma flow and renal filtration rate.5 6
A previous study had opined that athletes commonly display high resting urea concentrations, probably as a result of the continual stress of training. Urea concentrations are also generally increased after the performance of sports activity and may remain elevated for 24–40 hours after exercise.9 An increase in urea concentration may be related to a reduction in renal blood flow (and glomerular filtration rate) secondary to fluid volume deficiency, increased protein catabolism and/or bleeding into the intestine, all of which may occur after sports activity. Creatinine concentration (the product of creatine breakdown from skeletal muscle) also generally increases after sports activity. The increase in plasma creatinine concentration is probably the result of the release of creatinine from the working muscles, dehydration and/or a reduction in renal blood flow and glomerular filtration rate. The transient increase in creatinine and urea after strenuous exercise is thought to be of little clinical concern to renal function. However, some investigators have observed small but significant indices of renal damage after prolonged endurance exercise resulting from low blood flow to the kidney.10 Acute renal failure in some athletes after a sports event has been reported.11
It remains to be determined whether the repeated performance of prolonged endurance events leads to renal alterations that are of concern from a health point of view.
While there are robust documented reports on the effects of athletic sporting exercise (both endurance and brisk) on biochemical markers of liver and renal function, the same cannot be said about the effects of regular football sporting exercise on biochemical markers of liver and renal functions particularly among Nigerian sportsmen; hence, this study intends to evaluate changes in biochemical markers of renal and liver functions among young undergraduate men who play football on a regular basis.
