Introduction: Aerobic power or Vo2max which involves a full functional support from cardiorespiratory and metabolic pathway is an appropriate test to study cardiopulmonary fitness. Sufficient informations are not available on the extent of changes observed in different systems in untrained Indian subjects. The present study has therefore been undertaken to investigate the cardiovascular and respiratory responses to graded exercise and for determination of aerobic fitness among untrained males.
Material and Methods: The present study was conducted at Department of Physiology, Alluri Sitarama Raju Academy of Medical Sciences, From April 2013-March 2014. Hundred apparently healthy untrained men in the age group of 18-21 years were selected, to establish normal standards of cardiorespiratory responses to moderate, predetermined graded exercise on a bicycle ergograph. Parameters like heart rate, blood pressure and respiratory rate were recorded at rest, peak exercise and during recovery. Vo2max or aerobic power was calculated indirectly from Astrand – Ryhming nomogram after determining the work rate in kilopond meter per minute.
Results: Heart rate, systolic blood pressure, double product and respiratory rate rose linearly with increasing grades of exercise, while diastolic blood pressure recorded a fall. Mean arterial pressure was found to change very little. Aerobic power was found to be 49.19 ml/kg/min in 20 years age group and 49.16 ml/kg/min in 21 years category. The reduction in the systolic blood pressure during recovery period, after 5 minutes and 15 minutes was also analysed. Statistical analysis was done to compare it with the resting SBP. At the end of 5 minutes the systolic blood pressure showed a statistically significant increase from the resting SBP (p< 0.001).
Conclusion: During graded exercise the heart rate increased linearly, which could be due to sympathetic stimulation, increased venous return and withdrawal of parasympathetic inhibition. Systolic blood pressure rose linearly which reflects a normal sympathetic drive on cardiovascular system. Diastolic blood pressure decreased, may be due to decrease in peripheral resistance. Mean blood pressure changed very little. Double product also increased linearly and being an index of myocardial O2 consumption, showed a gradual fall during recovery.