Why Do My Biceps Look Smaller After A Workout? (Opinions Of Real Weightlifters)

The goal of lifting weights is to get them ripped or build mass not the opposite which is to lose muscle. Unfortunately our body's don't always cooperate and can work against us. That is why it is best to go by those that have been there and the science behind it. These days though lines are very blurred with one person saying one thing and another saying completely the opposite. I have always had problems with my biceps until I have changed my routine in the past year. Hopefully the information below will help you as well.

smaller biceps on guy working out

So why do my biceps look smaller after a workout?

Your biceps can look smaller after a workout for a few main reasons that we have listed below:

  • Overtraining
  • Not enough calories
  • Too much stress
  • Too much cardio
  • Muscle loss due to aging
  • After Muscle Pump

How Do I Stop My Biceps From Shrinking?

  • Don't Overtrain – look hard at your workout routine and make sure you aren't overtraining any muscle group and giving them enough time to recover. So for example if you are doing a 5 day routine working out each muscle group those 5 days you are probably overtraining your muscles. When you do push-pull workouts you are working multiple muscle groups and that means you are more then likely working the same muscle consecutive days in a row. Try a 3-4 day a week routine which will help alleviate this. I have seen lots of success with people doing full body training 3 days a week then cardio in between. This will depend on your goals of course, but reach out to some expert trainers or trainers of programs you have followed in the past.
  • Eat Enough Calories – If your biceps are shrinking and you want them to be bigger you have to feed that muscle in order for it to grow not just work them out. If you are already having enough calories dial in your micros. Up the protein and carbs you can check out our free macro calculator to see what you need based on age, height, and weight.
  • Live Stress Free – Most people do not realize what role stress plays in their lives. Cortisol is a muscle killer and what happens when you are over stressed from work or family situations. Try adding some meditation or books to help you calm down and remain as stress free as possible. I find what works best is getting everything done that I can first thing in the morning so my day feels accomplished before anyone else is even getting theirs started.
  • Cut Back On Cardio – It is okay to mix some cardio into your weight workout days and off days. If you are looking to put size on I would definitely keep your cardio for after you do your weight workouts or on your off days. If you are already doing this I would like at cutting back on the intensity of your cardio instead of running start jogging instead of jogging go to walking. When you elevate your heart for too long it cuts into those muscles for energy.
  • Supplement For Aging – as you get passed the age 30 your muscle starts to slightly decline especially once you reach the age of 40. The way you help stop this is by strength training which you are already doing. Another way is looking at supplements to help stop the breakdown process. Some initial areas to start is with a great multi-vitamin that includes Vitamin D, B (B12), Omega 3, Zinc among others. I prefer Smarty Pants Men's Gummy Vitamins myself as they have all this in it. You may want to add additional Fish Oil as well. When it comes down to it this may be out of your control and you may need to see a doctor to get on Testosterone Replacement Therapy. TRT will help stop the aging process in the muscles and get you back to your prime in a hurry.
  • Keep Muscle Pump – when you workout the blood flow increases to those muscles causing what is commonly called “The Pump”. Lactic acid builds up and draws water in this effect is only temporary so what you see isn't necessarily what you get. Your muscles will go back to their normal size this is what bodybuilders do back stage right before they go into the spotlight. Simply flexing your muscles will bring about a pump.

Why Do My Biceps Shrink After Workout? According To The Pros

So we didn't want you to only take our word for it on this matter. We went out and gathered information from several forums including weight training sub reddits and bodybuilding forums to get their opinions on why Biceps shrink after workouts. This information was curated so the only thing changed was any spelling or grammar where needed.

Real Weightlifter Opinions

1. Steez “Pump is gone” – I'm thinking it's because it's no longer pumped.

2. Awarewolf69 “Measure Before and After” – Next time measure your arms right before working out (no pump) and then again the next day. Turn this broscience into real science

3. Free-Penguin-Pete “Bloodflow has decreased” – I'd say it might look smaller after lifting as the muscle doesn't require the same increased bloodflow it needs while being worked. Personally, I don't really notice that, but to each their own I guess.

4. AlexanderTox “Muscle pump has worn off” – Never noticed that myself. I guess you could say that the muscle decreases in size once the pump wears off, but it's not drastically smaller.

5. SmellioTP “Either because broken down or pump gone” – To those saying it's because the pump has worn off, the pump pretty much wears off in my opinion that same day. The aspects that people seem to think about are, if you're breaking down the muscle, then it makes sense that it would be smaller. But the counter to that is that since you broke it down, the muscle is now inflamed causing it to look bigger. So it's more which of those two is a stronger factor, I believe

6. GanjaMilf “May psychological” – I notice the same effect, i think it is probably psychological but it might be that your muscles use the glycogen (a carbohydrate) stored in them for energy. Cells store water along with glycogen so a glycogen depleted muscle is less “full”. This is also why your muscles feel bigger when you eat a lot of carbs and smaller when you don't.

7. P_In_Their_Kettle “Never as big as your pump” – You'll never be as big as your pump

8. MrFaclonFarmsMelons “Swollen affect is gone” – That is normal. Some of the size you're seeing isn't really from gains, but from the muscles remaining in a swollen state for a few days after working out. The upside of this is it means going to the gym gives you an aesthetic boost for a few days, but the downside is you will “shink” a little when it goes away.

9. Psynz “Takes time to lose actual mass” – Some residual swelling might reduce but you aren't going to lose functional muscle mass in that time. I stopped going to the gym after 5 years of taking it quite seriously and it took about a years and a half to lose my mass (around 15kg).

10. ManoEMano “Take a break” – Taking a week off can be a great thing for gains as long as you don't eat and sleep like an idiot


Over 80% of posters mentioned the pump is probably just gone. So a way to combat that is to simply take your measurements before, right after and the day after to see how much your muscles are changing size. Around 4% mentioned that taking a break around a week could be a great thing to get through a plateau and explode those gains. So don't be afraid to do so and maybe just add in some steady state cardio like walking while also maintaining a healthy diet with balanced macros.


Tab Winner

We are fun loving family that lives on a small farm and tries to be healthy. We are not fitness fanatics we are just trying to keep things simple especially with how busy our lives are. We have a few horses, a few dogs, and a young daughter along with a big extended family. Follow us on our journey. I hope you enjoy the website. If you have any questions, feel free to contact us. Please check back for updates!

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