Study Information
Title: Microdosing of Flywheel Training: Effects of Low Versus High Training Frequency on Muscle Mass, Strength, and Power
Journal: International Journal of Sports Physiology and Performance
Link to Study: https://journals.humankinetics.com/view/journals/ijspp/aop/article-10.1123-ijspp.2025-0582/article-10.1123-ijspp.2025-0582.xml
Purpose and Background
Many research studies have found flywheel training to be an effective training method for a variety of purposes, whether the trainee is a competitive athlete looking to optimize performance and injury risk, or a recreational exerciser looking to improve their health and fitness (1,3,4). Most studies have used a standard session structure, involving 3-5 sets of flywheel exercises several times per week for each exercise.
However, there are cases where it could be useful to split up the training volume into small doses of flywheel exercise throughout the week. For example, during the middle of a busy competitive schedule, athletes may want to maintain or gain performance while minimizing the amount of fatigue or soreness that results from training. This type of approach could also be appealing to those that are constrained by time and would rather perform quick sessions more often than schedule longer sessions during the week.
This idea of splitting up the weekly training volume into small, frequent sessions is often referred to as microdosing. The main rationale is that smaller doses of training per day may result in better recovery and higher quality training sets due to less fatigue build-up within and across sessions (2).
While flywheel training has been used effectively in-season in previous research (5), no study has yet directly compared the effects of a microdosed flywheel training approach to a more typical approach of low frequency, higher volume per session.
Methods
Thirty recreationally trained participants were randomly assigned to one of two flywheel training groups. Both groups completed the same total training volume across the 6-week period, but the volume was spread differently throughout the week.
- Control Group: performed all volume on one day (5 sets of 8 reps)
- Microdose Group: spread the volume across five sessions per week (1 set of 8 reps).
The participants in both groups were asked to use maximal effort during the concentric phase, resist gently during the first 1/3 of the eccentric phase, and then brake maximally during the last 2/3 of the eccentric phase during each rep.
A variety of measurements were taken before and after the 6-week training period and compared within and across groups:
- Countermovement Jump measures (jump height, impulse, modified reactive strength index, time to takeoff)
- 30 cm Drop Jump measures (jump height, impulse, reactive strength index, ground contact time).
- Maximal Force during an isometric squat.
- Measures of muscle size and architecture for the Vastus Lateralis and Rectus Femoris.
Additionally, each trainee was asked to give a rating of perceived exertion at the end of each training session and a rating of muscle soreness 24 hours after each session.
Key Results
Performance Measures
Both groups made improvements in performance measures, such as countermovement jump height (5.9 - 7.7%) and modified reactive strength index (32.1 – 34.0%). Additionally, the Microdose group had a significant improvement in Drop Jump reactive strength index (24.4%).
Peak force during the isometric squat test also improved for both the Microdose (27.4%) and Control (18.6%) groups from pre to post.
Muscle Size and Architecture
While the between group analysis suggested no significant group differences, the Microdose group had significant increases in vastus lateralis muscle thickness (9.8%), fascicle length (11.8%) and fascicle angle (14.2%), which wasn’t seen in the Control Group.
Ratings of Perceived Exertion and Soreness
The two groups had differences in terms of average ratings of perceived exertion and soreness, with the Microdose group having significantly lower ratings during each week of the training period.
The Control Group tended to report relatively high ratings of perceived exertion and soreness (~7.5-8 out of 10) during the first week or two, with gradual decreases to moderate ratings (~4.5-6 out of 10) by the end of the six-week training program.
In contrast, the Microdose group tended to have low (~2-3.5 out of 10) average ratings for both perceived exertion and soreness throughout the entire training period.
Summary and Key Takeaways
Overall, this study found that spreading out the weekly training volume into small, single set sessions throughout the week resulted in significant improvements in measures of strength, jump performance, and muscle size and architecture, while involving consistently low ratings of perceived exertion and muscle soreness.
This has important practical implications for in-season training. By splitting up the volume into smaller, low volume sessions, the athletes may maintain or improve muscle adaptations and neuromuscular performance while managing overall fatigue and soreness.
This type of approach may also be highly useful in other populations or cases. For example, a busy trainee may find it easier to fit a set or two of flywheel training into their day compared to having to dedicate longer periods of time to training on certain days. Additionally, it’s possible that small, but frequent doses of flywheel training could be useful in rehab or clinical settings to provide the training benefits without the same degree of fatigue and soreness.
References
- Beato, M., De Keijzer, K. L., Munoz-Lopez, A., Raya-Gonzalez, J., Pozzo, M., Alkner, B. A., ... & Norrbrand, L. (2024). Current guidelines for the implementation of flywheel resistance training technology in sports: a consensus statement. Sports Medicine (Auckland, NZ), 54(3), 541.
- Cuthbert, M., Haff, G. G., McMahon, J. J., Evans, M., & Comfort, P. (2024). Microdosing: a conceptual framework for use as programming strategy for resistance training in team sports. Strength & Conditioning Journal, 46(2), 180-201.
- de Hoyo, M., Pozzo, M., Sañudo, B., Carrasco, L., Gonzalo-Skok, O., Domínguez-Cobo, S., & Morán-Camacho, E. (2015). Effects of a 10-week in-season eccentric-overload training program on muscle-injury prevention and performance in junior elite soccer players. International Journal of Sports Physiology and Performance, 10(1), 46-52.
- Sampietro, M., Campana, V., Pereira Thiem, L., Albarenque, M., Ribeiro de Oliveira, R., & Baroni, B. M. (2025). Effects of Flywheel Leg Curls on Muscle Structure and Function in Athletes with a History of Hamstring Strain Injury: A Randomized Controlled Trial. Sports Health, 19417381251355960.
- Timmins, R. G., Filopoulos, D., Nguyen, V., Giannakis, J., Ruddy, J. D., Hickey, J. T., ... & Opar, D. A. (2021). Sprinting, strength, and architectural adaptations following hamstring training in Australian footballers. Scandinavian Journal of Medicine & Science in Sports, 31(6), 1276-1289.
