The Effect of Strength Training Methods on Middle-Distance and Long-Distance Runners’ Athletic Performance: A Systematic Review with Meta-analysis

Abstract Background The running performance of middle-distance and long-distance runners is determined by factors such as maximal oxygen uptake ( V O 2 max), velocity at V O 2 max (v V O 2 max), maximum metabolic steady state (MMSS), running economy, and sprint capacity. Strength training is a proven strategy for improving running performance in endurance runners. However, the effects of different strength training methods on the determinants of running performance are unclear. Objective The aim of this systematic review with meta-analysis was to compare the effect of different strength training methods (e.g., high load, submaximal load, plyometric, combined) on performance (i.e., time trial and time until exhaustion) and its determinants (i.e., V O 2 max, v V O 2 max, MMSS, sprint capacity) in middle-distance and long-distance runners. Methods A systematic search was conducted across electronic databases (Web of Science, PubMed, SPORTDiscus, SCOPUS). The search included articles indexed up to November 2022, using various keywords combined with Boolean operators. The eligibility criteria were: (1) middle- and long-distance runners, without restriction on sex or training/competitive level; (2) application of a strength training method for ≥ 3 weeks, including high load training (≥ 80% of one repetition maximum), submaximal load training (40–79% of one repetition maximum), plyometric training, and combined training (i.e., two or more methods); (3) endurance running training control group under no strength training or under strength training with low loads ( 0.072). Moderators related to subject (i.e., sex, age, body mass, height, V O 2 max, performance level, and strength training experience) and intervention (i.e., weeks, sessions per week and total sessions) characteristics had no effect on running performance variables or its determinants (all p > 0.166). Conclusions Strength training with high loads can improve performance (i.e., time trial, time to exhaustion) in middle-distance and long-distance runners. A greater improvement may be obtained when two or more strength training methods (i.e., high load training, submaximal load training and/or plyometric training) are combined, although with trivial effects on V O 2 max, v V O 2 max, MMSS, or sprint capacity.