Effects of training two days per week at different intensities on middle-aged men1

Abstract

The purpose of this investigation was to determine the effects of training 45 min, 2 days per week, at 80% and 90% of maximum heart rate (max HR) on physiological measures of middle-aged men. Twenty-two men between 30 and 45 years of age (V = 38.7) were randomly assigned to one of two experimental groups. Group 1 trained at 90% of max HR and Group 2 at 80% for a total of 20 weeks. Twelve controls (Group 3) of similar qualifications were also evaluated. Exercise sessions were closely monitored on a quarter-mile track with total distance trained being equal for both groups. Intensity was estimated by the palpation technique (beats/10 sec) at 15, 30, and 45 min of training. Training results showed Groups 1 and 2 averaged 4.2 miles, and 509 Kcal per exercise session. Group 1 trained 44.4 min a day at 92% of max HR (173.0 beats/min) and Group 2 47 min at 80% (161.5 beats/min). Both experimental groups improved significantly in cardiovascular function, while spirometry and body composition measures remained relatively constant. This was shown by increased maxVo2 from 36 to 43 (+19%) and 38.5 to 44 ml/kg.min (+14%), maxVo2 from 132 to 147 (+11%) and 126 to 139 l/min (+10%), and max O2 pulse from 15.6 to 18.9 (+21%) and 16.9 to 19.8 ml/beat (+17%) for Groups 1 and 2, respectively. Group 1 showed a significant reduction in skinfold fat from 149 to 138 mm. Group 3 remained constant in all variables. Training 2 days/week had a significant effect on cardiovascular function, but little effect on body composition. Under the specific conditions of this experiment, differences in intensity had little effect.