How Quickly Can You Expect to See Muscle Gains?

Woman thinking about flexing

In today’s fast-paced society of “instant everything,” buying something online without having to leave your house isn’t enough; we also want it delivered the same day. It seems to be getting harder and harder to wait for anything. Even fitness is being rushed by people who seek out quicker and easier hacks to achieve what we used to be happy to accept as the long, hard road to greatness. Don’t get me wrong: I don’t think this is necessarily a bad thing. It’s just the way the world is moving.

Although, with the new research suggesting that erythropoietin (or EPO for short), the forbidden substance that cyclist Lance Armstrong admitted to using in his Tour de France victories, doesn’t actually work, maybe we have learned our lesson on trying to take shortcuts? Probably not … but that is not what I wanted to get into today. We’ll save that for another day.


For at least the last thirty years, trainers, athletes, and scientists alike have all assumed that the gains made in the first few weeks of a weight training program are an illusion. Not like the kind you see at a magic show or at a science museum but more of a biological slight of hand. The sport scientists all agree that the swelling caused by muscle damage is what makes muscles seem bigger and that for any real muscle size improvements you will have to wait at least six to eight weeks. Even the National Strength and Conditioning Association (NSCA) agrees with this timeline.

Well, a new study has just been published that seeks to turn some of these old body building ideas on their head. Or at least make a significant change to that timeline. Which is good news for you folks who are in a hurry to look buff at the beach this summer!

The new study, published by the National Strength and Conditioning Association is titled “The time course of short-term hypertrophy in the absence of eccentric muscle damage.” Which is a fancy way of saying: how long it takes to build muscles when you only move the weight in one direction. Yes, I know that still seems confusing, but I will break it down for you.

Eccentric versus Concentric

First, let’s talk about what the word eccentric means. According to the USCD page about Muscle contractions: “As the load on the muscle increases, it finally reaches a point where the external force on the muscle is greater than the force that the muscle can generate. Thus even though the muscle may be fully activated, it is forced to lengthen due to the high external load. This is referred to as an eccentric contraction.” Still confused? OK. Picture your mom doing a bicep curl with a huge dumbbell in one hand (fun, right?). When the dumbbell is moving down toward the floor, the bicep muscle is elongating which indicates an eccentric contraction. When she is moving the dumbbell up away from the floor, the muscle contracts which indicates a concentric contraction. Got it? Great! Let’s move on. Mom, you can take a knee.

In this new study, the researchers attempted to eliminate some of the confounding effects of swelling (that occurs because of muscle tissue tearing) by having the subjects perform only concentric muscle contractions. When the test subjects were doing biceps curls, like your mom just did, they lifted the weight upward, but then a lab-coat-clad scientist jumped out of nowhere and grabbed the weight out of their hand, lowered it for them, and then handed it back before the next repetition. This routine is how they avoided the eccentric contractions that are thought to induce majority of the muscle damage.

The reason they were so concerned with limiting the muscle damage and were focusing so closely on the potential swelling that might appear after crushing a hard lifting session was so that they could dispel some very particular criticisms of an older and similar study.

Back in 2011, a study titled “An examination of the time course of training-induced skeletal muscle hypertrophy” observed a remarkable 3.5% increase in muscle size (as measured by computerized tomography or CT scan) after just two workouts. Yes, a 3.5% increase after just two workouts!

Much to our chagrin, even the researchers that performed the study acknowledged that the initial increase was likely just a result of swelling (tissue damage) not pure hypertrophy (muscle growth) as they had hoped.

When we fast-forward back to this most recent study that uses the fancy lab-coat-clad, scientist-assisted, concentric contraction-only training, the results reinvigorate the claim that true muscle growth can indeed occur in less than four weeks.

In fact, with this one-direction training technique, the test subjects showed no signs of muscle damage or swelling, but they still showed what statisticians refer to as “statistically significant” increases in muscle size and weight after seven workouts during a 3.5-week period. In case you were wondering, the gains were assessed every seventy-two to ninety-six hours by:


  • level of soreness,
  • lean mass,
  • echo intensity,
  • muscle thickness,
  • relaxed and flexed arm circumference,
  • and isokinetic strength.

Not Convinced?

There are still some doubters out there, and they point to the fact that only 10 of the thirteen test subjects showed significant gains in muscle size, or “hypertrophy,” during the four-week study. I agree that is a rather small sample size, and with 3 of the participants failing to show results, I am left scratching my head and my chin. So, as with many scientific studies, this test likely needs to be repeated with a larger cohort before we start rewriting the text books.

I think it is also important to note that the thirteen “untrained men” who participated in this study performed a particularly heroic workout. The subjects did five or six sets of biceps curls and shoulder presses with eight to 12 repetitions. Each of the sets was performed to “failure,” which is that point in a workout when your eyes bug out, the veins in your forehead bulge, and you truly can’t lift the weight one more time. To top it off, between sets they were only given a measly ninety seconds to rest. This type of workout takes a certain amount of grit and determination but, if you feel so inspired, I think it is doable at your neighborhood gym. Just for the sake of your fellow gym goers, try to keep your grunting to a minimum.

Certainly it is important to remember that factors such as genetics, age, hormone levels, nutritional habits, as well as how hard you are willing and able to train, will always play a factor in how quickly any of us respond to any new fitness program.

Perhaps not all that relevant but still somewhat interesting (to me anyway) is that the subjects consumed 500 ml of whole milk during training. I hope it was at least chocolate milk, otherwise, no thanks.

In their conclusion, the researchers wrote: “In individuals beginning a resistance training program, small but detectable increases in hypertrophy may occur in the absence of eccentric muscle damage within seven training sessions.”

Certainly it is important to remember that factors such as genetics, age, hormone levels, nutritional habits, as well as how hard you are willing and able to train, will always play a factor in how quickly any of us respond to any new fitness program. That being said, I for one am pleased to hear that my new found bulging quad muscles aren’t simply puffy swelling from muscle tissue damage but are, at least in part, evidence that I totally crushed it on the squat rack—approximately four weeks ago.


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