Do Different Home-Based Resistance Training Programs Affect Running Economy and Plantarflexor Function in Middle-Aged Runners? An Exploratory Study

Endurance running exposure alone may not be sufficient to slow the age-related decline in plantarflexor function, which is also thought to contribute to the decline in running economy. Strength training has been shown to improve running performance, but specific programs have not been evaluated for their assistance in maintaining plantarflexor function and “youthful” metabolic costs in aging runners. The purpose of this study was to assess the relative influence of three types of resistance training interventions on running economy (RE), plantarflexor function, and Achilles tendon (AT) stiffness in middle-aged runners. Methods: Twenty-six middle-aged runners (51 ± 5 yrs) participated in one of three 10-week resistance training interventions: (1) heavy resistance training, (2) heavy resistance training + plyometrics, and (3) endurance resistance training + plyometrics. Laboratory testing for RE, biomechanical variables, peak plantarflexor torque, and AT stiffness during isometric contractions occurred before and after the interventions. A mixed-design repeated measures ANOVA was used to address our research question, while paired and independent t-tests were used to compare time and group effects, respectively. Results: Relative (to V˙O2max) RE (−2.4%, p = 0.016), AT stiffness (+26.1%, p = 0.002), and peak isometric plantarflexor torque (+26.4%, p = 0.001) improved with resistance training, with no interaction or group effects. No significant interaction, time, or group effects were observed for V˙O2max and peak plantarflexor torque, peak positive ankle power, or positive and negative ankle work while running. Conclusions: We present novel but exploratory findings that resistance training, regardless of modality, may moderately improve RE and Achilles tendon stiffness in middle-aged recreational runners. However, sagittal plane lower joint kinematics, extensor torques, powers, and work were unaffected by resistance training in middle-aged runners.