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Blood Lactate and Hormonal Responses to Prototype Flywheel Ergometer Workouts.


The purpose of this study was to compare blood lactate and hormonal responses with flywheel ergometer (FERG) leg presses for a preliminary assessment of workouts best suited for future in-flight resistance exercise.

The knee extensors are a muscle group prone to space flight-induced mass and strength losses. Longer flights usually result in greater losses, with the rate of strength loss exceeding that for muscle atrophy.

The stimulus for in-flight knee extensor losses is a lack of mechanical loading. Therefore, devices operating without gravitational resistance but still imposing high mechanical loads are best suited for space flight.

What They Did

28 subjects (14 men, 14 women) performed 3 flywheel ergometer workouts and submitted to blood lactate assessments pre-exercise and 5 minutes postexercise. A subset (7 men, 10 women) also submitted to venous blood draws before and at 1 and 30 minutes post-exercise to assess growth hormone, testosterone, and cortisol concentrations ([GH], [T], [C]) and to derive [T/C] ratios. The training program was comprised of 10 repetition sets and workouts entailed.

  • 3 sets of concentric and eccentric (CE3) actions
  • concentric-only actions for 3 (CO3), or
  • 6 (CO6) sets.

Before the start of FERG workouts, subjects performed a familiarization session to become accustomed to the operation of the device and reduce their risk of injury. The sample included 6 varsity athletes and 5 habitual resistive exercise participants.

The Ergometer resistance came from 2 flywheels joined by an axle that rotated in unison. A nylon strap connected the footplate and flywheels, so the resistance was imparted with each repetition. Subjects exerted forces against the footplate.

What They Found

It was concluded that because CO6 and CE3 yielded similar anabolic hormonal data, but the latter had a lower cortisol 30 minutes post-exercise, CE3 served as the best workout. Although the flywheel was initially designed for microgravity, the effort put forth by the study's subjects was more like that for workouts aimed at greater athletic performance and conditioning. These findings suggest eccentric actions should be used for flywheel workouts geared toward muscle mass and strength improvement.

Practical Application

Based on the mechanical loads imposed and the resultant hormonal milieu, the results of this study suggest that flywheel workouts should include eccentric actions. Many sports, strength, and conditioning programs include eccentric actions as a regular part of workouts, but in contrast to standard resistive exercise devices, the flywheel provides greater eccentric resistance.

The specificities of each load, exercise, and frequency will be based upon the athlete's requirements and their chosen sport. However, those looking to include FERG protocols for added muscle mass and strength should incorporate eccentric actions into their programme.

For further information on improving athletic performance with eccentric overloading, visit our markets page or book a free consultation today.


Caruso, J. F., Coday, M. A., Monda, J. K., Ramey, E. S., Hastings, L. P., Vingren, J. L., ... & Wickel, E. E. (2010). Blood lactate and hormonal responses to prototype flywheel ergometer workoutsThe Journal of Strength & Conditioning Research24(3), 749-756.

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