Can we actually prompt our muscles to grow?

1. Let's learn about effort during strength training and its relationship with muscle fatigue and how you can use effort to promote muscle growth in a way that doesn't involve lifting heavy weights. 
2. What do you think is the optimal weight to lift if you're trying to elicit muscle growth and how many times should you lift it? Resistance training experts, tend to speak in terms of something called percentage of 1RM, or Single Repetition Maximum. 
3. If you lift weights at 100 percent of your 1RM, then you're able to lift that weight only one time. You typically can lift 90 percent of 1RM, about two to four times and 80 percent of 1RM, probably 8-10 times and so on. 
4. You'll notice that the graph starts up here at 100 percent, then fall steeply first, and then gradually moves towards the horizontal. 
5. The heavier the load, the fewer repetitions we can perform, and the opposite is also true. 
6. The lighter the load, the more frequently we're able to lift it. 
7. For years, the conventional wisdom said that the weight hat to be heavy to build strength. But in recent years, we've discovered that's not actually true. 
8. Why are heavy load simply not necessary to generate muscle growth? In 2017, Andy Fugelvand from the University of Arizona, and Jim Potvin, at McMaster named  co-authored a landmark paper that established a model of the way human skeletal muscle fibers tires itself out. https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1005581
9. One big finding was that low force contraction sustained to endurance limits, induce more fatigue across all types of motor units compared to high force contractions. 
10. In plain language, that means lifting lower weights can tire out the muscles as much if not more than high weight repetitions. 
11. The study suggests that relatively low weights can still provide a potent exercise stimulus for muscle adaptation and health benefits. https://www.physiology.org/doi/full/10.1152/japplphysiol.00154.2016
12. To really simplify things, we've learned that there's a trigger in the body is switched, let's say that needs to get flipped for the body to know it has to build strength and a given muscle and it turns out that the switch is flipped whenever the muscle is worked with a high degree of effort. regardless how heavy the weights are that you're lifting. 
13. In a study, a group lifted heavyweights until they couldn't perform anymore reps, while the other group lifted lighter weights until they couldn't lift the weight anymore and the muscle grew the same degree in both groups. 
14. The research backed by James Model, shows that it doesn't matter how you fatigue all of the fibers in the muscle, whether you do it with heavier loads or with lighter loads. Whether you conduct three reps at 95 percent of 1RM, or 30 raps of 40 percent of your 1RM. So long as you're lifting that load until you have a hard time lifting it again, then the same training adaptation happens and your muscles grow. You become stronger. There is one caveat for competitive athletes or weightlifters who really are serious about maximizing muscle size and strength. Lifting heavy weights is necessary. But most of us aren't competitive athletes
15. If you're just looking to spur muscle growth and becomes stronger than lift weights enough times, you have to spend a high degree of effort at the end. 
16. Lifting of loads that require anywhere from three to 20 repetitions, or 90 all the way down to 30 percent of 1RM. We're talking about an exertion that's about eight or nine out of ten. So lifting lighter weights makes strength training a lot less intimidating for a lot of people. 
17. You're not going to get bigger or stronger by lifting a weight that's so light, you can do it 60 or 70 times. That's just too light. Try not to go above 30 repetitions.