‍Background/Purpose 

Aging is associated with declines in muscle strength, power, and balance, contributing to worsened physical function and frailty. Strength training is an effective countermeasure against these negative changes, and the eccentric loading and user-defined resistance offered by flywheel training may be particularly useful for aging populations. This study compared the effects of flywheel and traditional resistance training programs on measures of quadriceps strength and postural balance in older adults.  

Methods 

24 healthy older adults (average age of 69.9 years) were randomly assigned to either a flywheel group (n=12) or traditional resistance training group (n=12). Each group performed 3 training sessions per week for 12 weeks, with volume progressed over time. The flywheel group performed flywheel leg extensions with max concentric effort. The traditional training group used a standard leg extension machine at 80% of their 1RM. Measures of postural stability using a force platform, gastrocnemius tendon stiffness, and neuromuscular strength and power of the quadriceps and ankle plantarflexors were assessed before and after the intervention period.  

Results 

Here is a summary of the key findings: 

• The flywheel group had a larger increase in knee extensor power than the traditional group (+28% vs +4%).  

• The greater knee extensor power in the flywheel group was achieved with 25% lower EMG activity, indicating greater neuromuscular efficiency. In contrast, the traditional group had increases in EMG activity.  

• The flywheel group had a 46% greater improvement in single-leg postural balance time compared to the traditional training group (p<0.05), and this was accompanied by less pronounced center of pressure excursions (indicating greater stability during the test).  

• Gastrocnemius tendon stiffness increased by 136% in the flywheel group compared to 54% in the traditional group.  

• Improvements in the balance test were associated with improvements in plantarflexor strength and gastrocnemius tendon stiffness.  

Key Takeaways 

Overall, flywheel training resulted in superior improvements in knee extensor power, tendon stiffness, neuromuscular efficiency, and balance compared to traditional leg extension training in older adults. The benefits of flywheel training may have been at least partially due to changes in tendon stiffness and ankle strength, since changes in these measures were associated with balance improvements. The authors suggested the increased eccentric loading offered by flywheel training may be particularly useful for driving adaptations in the muscle-tendon unit and in neural adaptations such as motor unit recruitment and coordination. This could be particularly useful for older adults, who tend to experience drops in neuromuscular function over time.