Early Adaptations to a Two-Week Uphill Run Sprint Interval Training and Cycle Sprint Interval Training

This study sought to compare early physiological and performance adaptations between a two-week cycle sprint interval training (SIT) and uphill run sprint training (UST) programs. Seventeen recreationally active adult males (age = 28 +/- 5 years; body mass (BM) = 78 +/- 9 kg) were assigned to either a control (n = 5), SIT (n = 6), or UST (n = 6) group. A discrete group of participants (n = 6, age = 33 +/- 6 years, and body mass = 80 +/- 9 kg) completed both training protocols to determine acute physiological responses. Intervention groups completed either a run or cycle peak oxygen uptake (VO(2)peak) test (intervention type dependent) prior to and following two weeks of training. Training comprised of three sessions per week of 4 x 30-s all-out sprints with a four-minute active recovery between bouts on a cycle ergometer against 7.5% of body mass in the SIT group and on a 10% slope in the UST group. The VO(2)peak values remained unchanged in both training groups, but time-to-exhaustion (TTE) was significantly increased only in the UST group (pre495 +/- 40 s, post551 +/- 15 s; p = 0.014) and not in the SIT group (pre613 +/- 130 s, post634 +/- 118 s, p = 0.07). Ventilatory threshold (VT) was significantly increased in both training groups (SIT group: pre1.94 +/- 0.45 Lmin(-1), post2.23 +/- 0.42 Lmin(-1); p < 0.005, UST group: pre2.04 +/- 0.40 Lmin(-1), post2.33 +/- 0.34 Lmin(-1), p < 0.005). These results indicate that UST may be an effective alternative to SIT in healthy individuals.