You are probably well acquainted with muscle fatigue if you’ve been weight lifting for any length of time —the sensation of your muscles being “done,” “scrambled,” “toast”… you know, the “please have mercy before I’m permanently trapped under this weight,” or “you may just have to drag me off the bench because I’ve collapsed” feeling.
Typically, the term ‘fatigue’ is used to describe general sensations of tiredness and the accompanying decreasing muscular performance. What this really means is we “hit the wall” and can no longer perform “optimal” reps on a particular lift or produce the same output of muscular contractions as we did at the beginning of the set or workout.
What Causes Muscle Fatigue in Weight Lifting?
Fatigue is a phenomenon in which multiple muscle points fail during weight lifting. The underlying causes of fatigue fall into one of two categories. The first is ‘central,’ which refers to the neuromuscular/central nervous system (CNS). The second is ‘local,’ at the site of the muscle group.
The CNS acts much like the regulator of a vehicle’s engine. Most vehicles are made with a regulator that shuts the engine down when it revs too high for too long. This mechanism protects the engine from damage and overheating. Likewise, our brains attempt to protect our bodies by reducing the rate in which nerve impulses are sent to our working muscles.
In most cases, you’ll experience central fatigue before local fatigue. When you think you simply can’t do any more reps, what is happening is that your mind is telling your muscles to shut down. Essentially though you are probably able to continue for another couple of reps.
Local fatigue on the other hand refers to local factors that affect the ability to perform muscle contractions and the accumulation of metabolic byproducts such as lactic acid. These of course directly affect the contractile function of the muscle fiber. It includes the activity of energy systems such as ATP-CP, oxidation, and glycolysis. These three energy systems are used in much the same way as fuel in a car or a battery acid in a flashlight and are called upon at different times depending on the intensity and duration of an activity.
In weight lifting, the ATP-CP system is called upon during short but intense lifts, or muscle contractions. It works by repeatedly breaking down and rebuilding ATP using creatine phosphate (CP). During repeated maximal contractions, fatigue coincides with creatine phosphate depletion. This is why creatine is such a popular bodybuilding supplement.
The other two energy systems come into play during exercises that last longer than 30 seconds. Known as anaerobic (i.e. glycolytic) and aerobic (i.e. oxidative), these energy systems are dependent on the availability of glycogen.
Just as with the depletion of creatine phosphate, the rate of glycogen depletion is controlled by the intensity of the exercise. During sprinting, for example, muscle glycogen may be used up around 35 times faster than during walking. Glycogen depletion and low blood sugar limit performance in activities lasting longer than 30 minutes. Long-distance runners often speak of “hitting the wall” or “bonking.” This type of fatigue is usually caused by glycogen depletion. At this point, the body begins to use other forms of energy, such as protein and fat. These are not as efficient energy sources as glycogen, thus making it harder to sustain energy levels.
During high-intensity anaerobic exercise such as weight lifting, our bodies produce metabolic byproducts including lactic acid and CO2. As these accumulate, our ability to maintain the duration and intensity of an exercise diminishes. When finally a point of saturation is reached, our capacity for muscle contraction comes to a screeching halt. The muscle feels like it’s on fire which acts as a signal for you to take a pause.
So now that you understand the causes behind muscle fatigue, what can you do about it to maximize your weight lifting workout results? How can we assist our bodies to increase their output, and temporarily overcome the onset of muscle fatigue?
How To Overcome Muscle Fatigue
While we can’t overcome muscle fatigue completely, we can certainly delay it. Learning how to delay muscle fatigue can enable weight lifters to push out a few more reps and attain new levels of strength and muscle gains. There are many strategies we can use to accomplish this goal. Below are a few I’ve found over the years to be particularly effective:
The first strategy to overcome muscle fatigue is to stay properly hydrated. As you probably know, thirst is a sign that your body is already slightly dehydrated, so I am not talking about drinking water just when you’re thirsty. Dehydration can significantly affect your performance and workout potential, not to mention raise the risk of illness. Even a three to four percent drop in water levels can decrease your muscular contractions by 10 to 20%! To combat this, drink at least 10 to 12 eight-ouce glasses of water (not including sodas, coffee, or juices) spaced throughout the day, and whenever your body is perspiring.
There are lots of supplements on the market that can help bodybuilders delay muscle fatigue. Atheletes who weight lift for endurance may benefit greatly from combination carbohydrate and electrolyte drinks such as Revenge, Ultra Fuel, and G-Push. These contain scientific ratios of carbohydrates and electrolytes, salts and minerals that can replace those lost during prolonged exercise, in addition to enhancing the body’s ability to sustain more energy long-term.
Stimulants such as guarana and caffeine are often used to help delay fatigue for two reasons. First, it stimulates the secretion of hormones that initiate a release of fatty acids into the bloodstream, which cause the body to burn fat and spare carbohydrates to use as energy. Second, it postpones central nervous system fatigue thereby decreasing the perceived difficulty of the exercise.
If you find it hard to handle the jittery, nervous-type feeling you may get from stimulants such as caffeine though, you might give supplements like L-tyrosine or Ginkgo biloba a try. These supplements are not actual stimulants, so they do not affect your central nervous system (which causes the nervousness). Instead they help delay central fatigue in the brain to help crank up your workout intensity.
Finally, let’s not forget creatine monohydrate, which has been scientifically demonstrated to aid intense short-duration exercise like weight lifting. Creatine, as explained earlier, increases the body’s creatine phosphate stores needed to replenish ATP, thereby delaying the onset of glycolysis. Creatine helps quickly replenish energy stores within the muscle cells, allowing you to work out longer and harder, which may lead to increased strength and muscle gains.
Resting Between Sets
Giving your muscles adequate rest between sets is important for delaying premature fatigue. Inadequate rest during weight lifting can cause fatigue that could otherwise have been avoided. However, rest does not mean to stop moving. Recent research that studied the effects of recovery between sets showed that active movement after completed sets allowed weight lifters to perform more reps in later sets compared with those who recovered passively between sets. This indicates we should keep moving during rest periods. Instead of sitting down to rest, exercise a different muscle group or walk around.
To determine the proper amount of rest time, a standard rule of thumb is to rest just long enough to catch your breath. If you’re training a large muscle group by doing squats for example, give yourself a little more time – maybe two or three minutes. For smaller muscles like biceps, you a much shorter rest time is recommended — just 45 to 60 seconds at most.
One of the most prolific errors I see with both beginner and advaced weight lifters is over-training. Influenced by a “more is better” mentality, many of us seem to think if we train longer, harder, and more frequently, we’ll multiply our results. However, nothing could be more detrimental to your muscle- and strength-building efforts. This is because overtraining can significantly impede the body’s ability to properly recover and rebuild itself, which is necessary to build strength and mass. Only by giving your muscles adequate time to rest and getting enough sleep will the body be able to recover and rebuild itself.
You may be overtraining if you are experiencing the following: lethargy, chronic fatigue, continued muscle soreness, insomnia, and a decrease in strength. If so, try taking off another day in between training sessions or switching up your routine, and see how you feel. Don’t train a muscle if it’s still sore. Remember that recovery times are faster when you are exercising smaller muscle groups, or when you are using higher reps with lighter weights. Longer recovery times are needed for more intense workouts with heavier weights.
So there you have it. You are now armed with practical, sound methods to overcome muscle fatigue, so you can train harder and longer, and become stronger, both mentally and physically.