Short, fast running such as uphill intervals and sprints can improve running economy and 3-5 km performance in trained runners, but classic strides and triathletes are untested
Interpretation
Several small trials in trained runners point the same way: uphill intervals improved 5-km time by 2.0% and economy by 2.4% (Barnes 2013, n = 20); 30-s sprints improved economy by 5.7-7.6% (Iaia 2009, n = 17) and 3,000 m time by 5.31 s more than control (Jin 2025, n = 20 men); explosive training improved 5-km time and economy without raising VO2max (Paavolainen 1999, n = 18). Samples were 16-20 people, mostly young and male, one trial had no control, and replacing most running with sprints did not change 10-km time. No trial tested submaximal strides or triathletes.
Practical implication
Adding a few strides or short hill sprints to easy runs is a low-cost, low-fatigue option for age-group triathletes, built up gradually. It is an add-on to aerobic training, not a replacement, and benefits for long-course racing are extrapolated from 3-10 km data in young, mostly male runners.
Sources
5 sources, independently verified.
Runners were randomised to one of five uphill interval programmes of different intensity for 6 weeks. 5-km time-trial performance improved by 2.0% (±0.6%) on average with no clear optimal intensity; running economy improved most at the highest intensity (2.4%, ±1.4%). No flat-running comparison group, and each programme group was very small.
For 4 weeks the intervention group replaced about 45 km/week of running with 8-12 x 30-s sprints (5.7 km/week) plus 9.9 km/week at low speed. Submaximal oxygen uptake fell by 5.7-7.6% at 11-16 km/h, but VO2max and 10-km time did not change in either group.
10 x 30-s all-out sprints with 3.5 min recovery, twice a week for 6 weeks, versus traditional distance training. 3,000 m time improved from 527.48 to 522.61 s and by 5.31 s more than control (d = 1.53); VO2max and oxygen-cost changes were not significant. Men only, small sample, 6 weeks.
Over 9 weeks with total volume held equal, 32% of training (vs 3% in controls) was replaced by explosive-type strength training. 5-km time, running economy and maximal anaerobic running speed improved in the experimental group only; VO2max did not change in that group. Changes in 5-km speed correlated with changes in economy (r = −0.54) and maximal anaerobic speed (r = 0.55). Small sample; explosive training is not the same as strides.
Six sessions over 2 weeks of 4-7 x 30-s maximal shuttle runs with 4 min recovery. 3,000 m time trial 6% faster, maximal aerobic speed +2.3%, time to exhaustion at 90% of it +42%. Pre-post design without a control group.