Akca, F and Aras, D. Comparison of rowing performance improvements following various high-intensity interval trainings. J Strength Cond Res 29 (8): 2249–2254, 2015—The purpose of this study was to examine the effects of high-intensity interval training (HIT) and supramaximal interval training (SMIT) on indoor rowing performance; 20 male lightweight collegiate rowers (age= 21.77±2.35 years, height= 178.4±6 cm, body mass= 69.6±3.1 kg) participated in this study. Baseline testing involved a 2,000-m time trial and incremental exercise test to determine V [Combining Dot Above] O 2 peak, peak power output (PPO), and power at 4 mmol· L− 1 blood lactate threshold. After the baseline tests, participants were allocated to SMIT or HIT intervention groups, which they performed 8 times over a 4-week period (2 times per week, 2 days apart). The SMIT involved 10× 30-second intervals at 150% of the PPO with 4-minute rest. The HIT involved 8× 2.5-minute intervals at 90% of the PPO with 3-minute rest. Of note, 5.7 and 5 seconds of improvements were observed in 2,000-m performance after SMIT and HIT interventions, respectively. Of note, 2,000-m time trial performance, 2,000-m power, PPO, relative, and absolute V [Combining Dot Above] O 2 peak were significantly improved after both training interventions. However, the differences between the groups were not significant. As a result, 4 weeks of SMIT improves 2,000-m rowing ergometer performance and related physiological variables in a similar fashion with HIT in collegiate rowers.