If you aren't flexing for muscle size why not? There is a reason bodybuilders flex like crazy on stage and when they are asked to pose for a PR shot. Not only does it allow them to hit the required poses, but it also pumps up the muscles. It also harks back to the little boy psyche when someone asked you to show your muscles and you sprang into a really bad "most muscular" pose.
Refer to the classic section in Pumping Iron when Arnold and Frankie go for a ballet session to work on their posing. Ballet dancers are extremely adept at activating their muscles and holding them in pose for sustained periods of time. Master this and you will hold posers longer without cramping and increase strength and flexibility.
Where's The Science?
Ok so this study by the European Journal of Sport conducted this 8 week research study on the effects of increasing the mind-muscle connection during bodybuilding routines, which involved contracting the targeted muscle groups over 3 training sessions per week. On conclusion of the study the group that flexed increased their strength and muscle size by 12.4%. The group that didn't made gains in the respect of 6.9%.
So the group that contracted their muscles hard during their sets made a 50% increase almost in muscle thickness and strength. The mind muscle connection clearly works. Bodybuilders have been doing this religiously for decades. Some more so than others.
So why would you not flex if it can potentially shortcut your muscle building time by 50%? Here at X Boom Fitness we believe less is more when it comes to muscle building and cardio. Do more in less time. Kick 10k to the kerb, Salvage your time, your life, your relationships, your marriage by spending time where it matters.
Ok when you are young you are No 1, but priorities change over time, and rightly so...
But there are beneficial reasons for flexing outside the gym. It all correlates with the mind-muscle connection. If you can isolate a muscle correctly and delimit all adjoining muscles during a set you are going to work that muscle harder. If the muscle you are working, say the bicep, is doing most of the work it is going to grow significantly better than if you just haul the weight up like a peach fuzz rookie.
If you are using momentum you are taking the pressure off the bicep. You are leaking energy and the slack is being taken up by the back, hips, shoulders and legs. If you want your biceps to grow more effectively forget about performing standing cheat curls as your main set. Cut the weight, don't swing for the fences and curl only with your biceps.
You can finish on cheat curls at the end, but remember they are called that for a reason. I'm not negating any potential gains but everything in it's right place.
Can You Build Muscle Alone By Flexing?
Not specifically. In order to build muscle you need to place a new load on the muscles. Your diet and calorie surplus will ensure your body uses the required amount of protein for synthesis into muscle. The amount of protein and calories you need is specific to you, it's a process of trial and error.
Some studies show it's 1 pound of protein per pound of body weight, Others show it's less- 0.8 lb, others more in the region of 1.5 lb. For this you will have to use trial and error, get a calorie tracker and start counting your macros- the hardest part in bodybuilding or general muscle building routines.
Your body can only absorb up to 30g of protein in one sitting so taking 10 scoops of whey or eating 5 chicken fillets in one meal is not ideal. Your body will still use the calories but it won't be solely specific to building muscle if you cram so much protein into your body in a single sitting.
This extensive Government study shows that ideal protein absorption is between 1.6g to 2.2g per actual kg of body weight. It depends also on the type of protein whether it is fast absorbing or slow absorbing. Slowly digestible proteins in larger doses may be better utilized than fast absorbing proteins.
There is a massive myth in the fitness industry that everything is about protein and how much you need. It is usually always over estimated. By knowing the facts and testing it out on yourself you will find the ideal ratio for you. If you take more than you need- especially from whey protein, it isn't necessarily going to do much harm, except to your wallet and potentially to bloating and gas.
Watch the mirror, watch the scales and judge for yourself. Or get a friend who understands physique transformations and bodybuilding to judge for you.