Physical conditioning through interval training with young male adults

Swedish military conscripts participated in 3 separate programs of interval training (principal activity - running): Group I (N = 20): 15 sec exercise + 15 sec rest, 3 days/week for 2 months. Group II (N = 9): 3 min exercise + 3 min rest, 3 days/week for 2 months, Group III (N = 8): 1 month no formal program, then 3 min exercise + 3 min rest, 5 days/week for 1 month. For each group, total time for exercise of high intensity = 15 min per session. Testing was performed on a cycle ergometer at induction, after 1 month, and after 2 months. Significant increases in maxV̇o2 were observed for all groups (mean increase approximately 20%). Maximal oxygen uptake increased from 3.1, 2.9 and 3.2 to 3.6, 3.6 and 3.9 ] × min−1 for groups I, II and III, respectively. Concomitant reductions occurred in HR and perceived exertion at submaximal exercise (150 W). Individual improvement was inversely related to initial fitness, the lower the level at induction the greater the increase relative to this value. Subgroups tested 8 months after cessation of training (at discharge) had regressed to levels not different from those at induction. Conclusions: 1) physical fitness in this age group can be markedly and rapidly improved by interval training, 2) marked improvement in aerobic power capacity can be brought about by an impressively short time investment, 3) the training regimen based on 3-min periods was more effective than 15-sec periods, and 4) military life in this situation (communications regiment) was not sufficient to maintain a high level of fitness when the physical conditioning program was discontinued.