If you ever wondered what specifically helps your muscles get larger, you can rely on the hormone IGF-1. IGF-1 stands for insulin-like growth factors, and its benefits create much interest in individuals looking to increase muscular size. IGF-1 and human growth hormones -- hGH -- are closely entwined. The National Strength and Conditioning Association reports that the effects of hGH are mediated through IGF-1, and its release has been shown to be highly correlated with natural anabolic protein growth. By stimulating the release of IGF-1 and its hormonal companion hGH, you greatly increase the likelihood of gaining muscular lean tissue in a healthy manner.
- Skill level:
- Moderately Challenging
Perform resistance exercises with intensities that are 85 to 100 percent of your 8 to 15 repetition maximums. Use 8 to 15 reps to place your set in the hypertrophy zone, because this zone is responsible for muscular size gain. Lift intensities that are 85 to 100 percent of your 8 to 15 rep maximum, because this triggers human growth hormone release, which in turn helps release IGF-1. Execute at least three sets, and rest no more than a minute between sets. Target large or multiple muscle groups for optimal results.
Sprint short distances -- 20 yards, 40 yards, 100 m -- with interval training. Rest in between sprints at a ratio that is equal to the entire duration of the sprint at minimum, or three times the duration of the sprint at maximum.
Run at an intensity of 75 to 79 percent of your maximum heart rate continuously for at least 10 minutes. This keeps you in the high-intensity portion of the aerobic zone, and just under the anaerobic zone and lactate threshold, in which 10 minutes of continuous running cannot be met.
Supply yourself with adequate rest. Sleep roughly eight hours a night to trigger hGH and IGF-1 release.
Eat complete protein and complex carbohydrates before and after a training session, because IGF-1 is sensitive to the acute intake of both macronutrients.
Increasing IGF-1 Levels
Tips and warnings
- Make sure you are performing within the exercise intensity parameters. The serum levels of the IGF-1 and hGH hormones in the blood will not increase naturally unless high stress is met.
- Do not overtrain. Give your muscles ample rest, as training at these intensities can cause excessive muscular fatigue.
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- "Essentials of Strength Training and Conditioning,"; Thomas R. Baechle, Roger W. Earle; 2008.
- "Expression of Insulin Growth Factor-1 Splice Variants and Structural Genes in Rabbit Skeletal Muscle Induced by Stretch and Stimulation,"; G. McKoy, et. al; Journal of Physiology 516 (Pt 2): 583-592; 1999.