Effect of concurrent strength and endurance training on run performance and biomechanics: A randomized controlled trial.

This randomized controlled trial asked whether adding strength training to a distance runner's routine improves running performance more than endurance training alone, and whether any such improvement is linked to changes in running technique. Thirty moderately trained runners who ran at least 30 km per week and had no prior strength training experience were assigned to either 10 weeks of concurrent strength and endurance (CSE) training or a control group of continued endurance training. The primary outcome was 2-km run time.

The CSE group improved 2-km time by an average of 11.3 seconds compared with controls, and also showed a longer time to exhaustion during a maximal aerobic capacity test and a small reduction in body fat. However, of all the biomechanical and muscle activity measures examined during running, only hip angular velocity in early swing phase changed significantly, suggesting the performance gains were not clearly explained by changes in running mechanics. The trial was small, with 15 participants per group.

This study looked at whether runners who add strength training to their usual endurance running improve their race times more than those who just keep running as usual. Thirty runners who already ran at least 30 km a week, and who had never done strength training before, were randomly split into two groups: one added 10 weeks of strength training alongside their running, the other continued with endurance training alone. The group that added strength training ran a 2-km time trial about 11 seconds faster on average than the control group, and they also lasted longer on a treadmill test measuring aerobic fitness, and lost a small amount of body fat.

Interestingly, when researchers looked closely at running form and muscle activity, almost nothing changed except for one measure related to hip movement during the early part of the leg swing. This suggests the performance benefits weren't clearly explained by changes in how people ran. The study only included 15 people per group, so the results give an early signal rather than a definitive answer, and it's not certain how well these findings would hold up in larger groups of runners.

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This RCT examined whether 10 weeks of concurrent strength and endurance (CSE) training improves distance running performance and whether biomechanical or neuromuscular changes underlie any such improvement, comparing 15 CSE-trained runners against 15 endurance-only controls in moderately trained runners averaging 30+ km/week with no prior resistance training history. The CSE group showed a statistically significant improvement in 2-km time (mean difference -11.3 s, 95% CI -3.7 to -19.0) and longer time to exhaustion during VO2max testing (MD 59.1 s, 95% CI 8.58-109.62), alongside a small reduction in total body fat, with lean mass and total mass unchanged.,Despite these performance gains, comprehensive assessment of sagittal plane lower limb kinematics and muscle activity during overground running at a fixed submaximal speed and during maximal sprinting revealed only one significant change: hip joint angular velocity during early swing phase at 3.89 m/s.

This dissociation between performance improvement and biomechanical/neuromuscular adaptation suggests other physiological mechanisms, not captured by these outcome measures, may explain the benefit. The sample size (n=30 total) limits generalizability and statistical power for secondary biomechanical outcomes, and the authors note that fatigued or prolonged running conditions were not assessed, leaving open whether biomechanical changes might emerge under those conditions.