Popeye the Sailor Man famously powered up by eating canned spinach, using its muscle-building properties to save Olive Oyl time and again. While it may have seemed far-fetched, new research shows that spinach extracts containing the plant hormone 20-hydroxyecdysone combined with strength training can in fact dramatically boost muscle strength and quality. Read on to separate spinach fact from fiction!

A recently published 12-week randomized, double-blind, placebo-controlled trial examined the effects of taking a Spinacia oleracea extract supplement while doing strength training in adults over 50.¹ The supplement provided a daily dose of 2 grams of a spinach extract standardized to 1.6 milligrams of 20-hydroxyecdysone (20E), delivered in four 500 milligram capsules. 20E is a phytoecdysteroid found in high amounts in spinach and other plants that has been shown to have anabolic and adaptogenic properties.²

The 45 subjects took the spinach extract containing 20E or a placebo along with completing an hour of supervised resistance training focused on the major muscle groups three days a week. The study measured muscle strength using isokinetic testing that quantifies torque and power produced by the knee extensor muscles. Muscle quality was calculated by dividing muscle strength by muscle mass.

The spinach group experienced significantly greater improvements in peak knee extensor torque, total knee extension work, and muscle quality compared to strength training alone. For example, peak torque at fast (180°/sec) knee extension velocity increased by 23.6% with spinach extract versus only 5.4% for placebo. Isometric knee extensor strength and overall lower body muscle quality showed similar statistically significant benefits from the spinach 20E supplementation.

20E likely works by activating cellular pathways leading to increased protein synthesis and blocking muscle breakdown,³ while the nitrates spinach contains boost muscle contractility and efficiency.⁴ This complements the size and strength gains stimulated by resistance exercise.

Previous studies have also shown that 20E can increase protein synthesis, muscle fiber size, and strength when combined with strength training.^5,6 It appears to interact with membrane receptors that regulate muscle growth, including angiotensin and possibly estrogen receptors.⁷

While more research is still needed, these exciting findings lend credence to the legendary muscle-boosting effects of spinach made famous by Popeye. The sailor man's reliance on canned spinach to save the day turned out not to be so far-fetched after all! Consuming spinach extracts standardized for 20E could be an effective, natural way to build strength and maintain fitness as we age.

Learn more about the health benefits of spinach and leafy green vegetables at the following databases: Spinach and Leafy Green Vegetables.

Learn more about how to build muscle here.

References

1. Pérez-Piñero, S. et al. Nutrients. 2021 Dec 6;13(12):4373.

2. Dinan L. et al. Biomedicines. 2021 Mar 26;9(4).

3. Gorelick-Feldman J. et al. Steroids. 2010 Oct;75(10):632-7.

4. Jones A.M. et al. Annu Rev Nutr. 2018 Aug 21;38:303-328.

5. Isenmann E. et al. Arch Toxicol. 2019 Oct;93(10):1807-1816.

6. Parr MK. et al. Steroids. 2015 Oct;99(Pt B):134-40.

7. Lafont R. et al. Front Pharmacol. 2021 Feb 16;12:629066.