‍Background/Purpose 

Strength training has been identified as a strategy to improve mechanical efficiency during endurance running. The eccentric loading offered by flywheel training may be particularly useful for targeting this quality.  This study evaluated whether adding one flywheel strength session per week to an endurance training program would increase strength and running economy compared to groups that performed endurance training only.  

Methods 

Twenty-nine recreational runners (ages from 27-57 years) were randomly assigned to one of three groups for 8 weeks of training:  

1. High Intensity Endurance Group: Performed high-intensity endurance training 3 times per week.  

2. Low Intensity Endurance Group: Performed low-intensity endurance training 3 times per week.  

3. Flywheel Group: Also performed low-intensity endurance training 3 times per week, but added 4 sets of flywheel leg press one day per week.  

A variety of measures were taken before and after the 8-week training period, including 2km and 10km time trials, maximal oxygen uptake (VO2max), max velocity at VO2max, velocity at ventilatory thresholds (VT1 and VT2), running economy at 75% of velocity of VT1, and leg press 6 repetition maximum (6RM).  

Results 

• The flywheel group had significant improvements in running economy (6.2%) and leg press strength (+12.9%), while the endurance training groups did not.  

• All groups improved their average velocity during the 2km and 10km time trials. 

• Compared to the low-intensity group that performed similar endurance training, the flywheel group had larger improvements in time trial performance (2km: 3.7% vs 2.9%; 10km: 6.1% vs 2.5%). The flywheel group also had similar improvements compared to the group that performed higher intensity endurance training (2km: +3.7% vs +3.8%; 10km: +6.1% vs +5.8%). 

• VO²_Max did not significantly increase in any group.  

Key Takeaways 

Adding just one session of flywheel training to an endurance program can improve running economy and lower body strength compared to performing endurance training only. This also resulted in time trial performance improvements that were larger than the group that performed similar endurance training, and similar to the group that trained at higher endurance training intensities. Given that running economy improved, but VO²_Max did not, it is likely that the benefits of flywheel training are neuromuscular rather than cardiovascular. A likely mechanism is improved mechanical efficiency and more efficient elastic energy use during running due to flywheel training’s eccentric loading and stretch shortening cycle demands.