Effects of high-intensity interval training and resistance training on physiological parameters and performance of well-trained runners: A randomized controlled trial.

Researchers gave 26 well-trained male runners one of three different four-week training programs: high-intensity interval training (HIIT), heavy resistance training, or explosive resistance training. They measured changes in aerobic fitness, anaerobic capacity, muscle strength, power, and racing performance across 1500m and 5000m distances. Each training type produced somewhat different results.

HIIT improved the speed at which runners could sustain their maximum oxygen uptake and helped them run faster over 1500m. Both resistance training approaches increased the anaerobic threshold, which is the intensity level at which the body shifts toward producing more lactate. Resistance training also built significant strength gains, while explosive training produced the largest jumps in jumping power.

The practical takeaway is that different training methods appear to drive different physiological adaptations, and both resistance work and HIIT may have a role in periodized training plans for distance runners.

This study looked at what happens when distance runners follow different training programs for just four weeks. Three groups of well-trained runners either did high-intensity interval work, heavy weight training, or explosive power training, and researchers measured changes in fitness, strength, and race times.

The interval training group got better at sustaining their hardest efforts and ran faster in the shorter 1500m race. The weight training groups became stronger and better able to work hard for longer periods, and both also ran faster over the longer 5000m distance.

Everyone improved their jumping ability, though the explosive training group saw the biggest gain. The study suggests that mixing different types of training may help runners improve in different ways, though four weeks is a short window and different runners may respond differently to these approaches.

This is a summary of research, not medical advice. Talk to your own healthcare provider about anything affecting your care.

This RCT adds modest evidence that resistance training and HIIT produce distinguishable adaptations in well-trained distance runners over a short training block. HIIT showed a small but meaningful effect on velocity at VO2max (2.6%, ES 0.63), the metric most directly related to sustained aerobic performance, while both heavy and explosive resistance training produced larger gains in anaerobic threshold (4.3% to 6.9%, ES 0.72 to 0.73).

The strength data are unsurprising but substantial: heavy resistance training drove 1RM gains of 38.1% (ES 1.21) and explosive training 49.2% (ES 0.96), whereas HIIT produced only modest power gains by comparison. The race time improvements were small but split along expected lines, with HIIT favoring the shorter effort and both resistance modalities improving the 5000m.

The sample size is modest and the intervention window brief, so these findings are best viewed as signals rather than definitive adaptations. The data support the authors' conclusion that different training methods may occupy distinct roles in periodization, though longer-term training studies and mechanistic work remain needed to clarify when and how to sequence these approaches.