Exercise places your body under substantial stress but that stress is necessary for your body to adapt and change to occur. Just as your body has to be stressed to change, it needs adequate time for exercise recovery as well. Without adequate recovery, your body can’t completely repair the microscopic damage that muscle fibers sustain so that growth can occur. A number of factors can impact how quickly your muscles recover from exercise. Here are some you should know about.
Recovery is Quicker for Steady-State Exercise
When you work out at a steady pace, below your lactate threshold, exercise recovery is more rapid than with high-intensity workouts since there’s no build-up of lactate. When you do high-intensity exercise, recovery is more prolonged since your body has to remove lactate, oxidize it or send it to the liver to be converted to glycogen. Your core body temperature will be higher after high-intensity exercise and it takes longer for your body to cool, your heart rate and respiration to slow and the more substantial oxygen debt to be repaid.
After high-intensity exercise, there are higher levels of catecholamines in your blood as well as more growth hormone than with steady-state exercise below your lactate threshold. The extra energy that must be expended to bring your body back to its baseline is called EPOC or the after-burn effect. You may recover quickly from steady-state exercise, but your body will make adjustments for hours, and some say days, after a high-intensity workout. This uses more energy. That’s why some studies suggest that high-intensity exercise is so effective for fat loss.
What about recovery from resistance training? Intensity matters here too. If you lift heavy, do super-slow sets or lift to near failure, your muscles need more recovery time than if you train lighter and do more reps. You’ll break more fibers with intense strength workouts, meaning your muscles need more time to recover, as much as 3 days.
The Impact of Age on Recovery Time
The type of exercise you do, steady-state or high-intensity, is one factor that affects recovery time. Age is another. You need more time to recover from exercise as you grow older. A study published in the Journal of Gerontology showed that older men were slower in recovering after sub-maximal exercise in terms of how fast their heart rate came down and how quickly their body temperature returned to normal. Because of this, older people who work out are more prone to dehydration and heat stroke when exercising in a warm environment. On the other hand, hydration is important at any age!
What Muscles Are You Working?
In general, large muscle groups need more recovery time than smaller muscle groups. Smaller muscles like biceps and triceps may only need to recover for 48 hours whereas larger muscle groups like chest muscles, back muscles, and muscles in the lower body need longer. When you work larger muscle groups or do compound exercises, you’re recruiting more muscle groups. Thus, you need more recovery time due to greater stress and damage.
Cortisol and Exercise Recovery
Another factor that impacts exercise recovery is the hormone cortisol. Cortisol is released in response to stress including severe calorie restriction, overtraining and sleep deprivation. When cortisol levels are high, it creates a catabolic environment that makes it difficult for muscle fibers to recover, adapt and grow. That’s why you need adequate sleep and nutrition to build lean body mass and to maintain the lean body mass you have.
You can help your muscles recover by consuming a snack of protein and carbs within an hour after an exercise session. There’s a window period where your body is primed to use these macronutrients immediately after a workout. Eating a snack that contains carbs also helps to lower cortisol levels.
How Active Are You When You’re Not Working Out?
This is a factor many people don’t consider. If you have a very active job that requires lifting or other strenuous activity, you need to space your workouts out more to reduce fatigue. In this case, it’s also important to get adequate sleep and good nutrition to fuel all of the activity.
The Bottom Line?
Exercise recovery is vital for muscle growth. It’s during the times you’re resting between workouts that your muscles are growing and repairing. Make sure you’re giving them the rest time they need.
Journal of Gerontology. 2006, Vol. 61A, No. 1, 63–71.
Journal of Strength and Conditioning Research. (2008) 22(3): 1015-1024.
Current Opinion in Clinical Nutrition and Metabolic Care 2001, 4: 527-531.