Maximal 4-Second Cycle Accelerations Attenuate Sarcopenia and Improve Cardiovascular Function in Older Adults

The shrinkage of muscles with age, beginning at 30 y and accelerating in old age, is due largely to atrophy of fast-twitch muscle fibers (FT) partly from disuse. It was our purpose to develop an exercise program that is effective and time efficient at stimulating FT, as well as slow-twitch fibers (ST), to offset their atrophy. FT are recruited during movements requiring very high force and/or high velocity. We developed a safe exercise cycle that allows a person to ‘accelerate’ with the maximal effort needed to recruit the highest number of ST and especially FT fibers. ‘Inertial Loading’ allows the person to maximally accelerate the cycle flywheel through the full range of the force vs. velocity relationship (0-160 RPM), and accurately identifies maximal power (Pmax), which can be used to diagnosis muscle loss. Of note, Pmax is usually five-fold higher than the power encountered during any aerobic exercise or ‘High Intensity Interval Training (HIIT)’. The very high Pmax serves as a very potent stimulator of the muscle, the nervous system and the cardiovascular system. This remarkably reduces the total exercise time (1-2 minutes) needed in a 10-minute workout, which is comprised of repeated 4-second accelerations and 15-45 seconds of recovery. The 4-seconds of maximal acceleration robustly activate FT, based on increases in mRNA from genes and pathways involved in muscle hypertrophy. Furthermore, NASA experiments used these cycle accelerations during 70 days of bed rest, that simulates muscle atrophy with space flight but also aging. NASA reported that performing 24 seconds (4 s × 6) of maximal acceleration cycling every 8 days, along with less frequent short bouts of aerobic exercise, totally prevented the normally large atrophy of FT, and it reduced the whole muscle atrophy by one-half. Specifically, when older adults train with maximal accelerations for 8 weeks, they display significant hypertrophy of their thigh muscles, increases in maximal power, and better performance in tasks of daily living. The cardiovascular system also improves function with these repeated high-power sprints and short rest, with significant increases in heart function, maximal oxygen consumption and arterial elasticity. Therefore, performing repeated maximal 4-second accelerations on an inertially loaded cycle ergometer, beginning at 30 y and continuing throughout old age, has promise to be a safe and viable proactive treatment to both diagnosis and counteract the progression of muscle wasting, sarcopenia and reduced cardiovascular function.