A workout can be a great way to unwind after a stressful day, but ruminating over that unpleasant meeting with your boss may make your exercise session less effective.
New research suggests that if your brain is tired, the rest of your body may be tired as well, because the two go hand in hand. Why is it that mental and physical fatigue are so closely connected?
Part of the answer is that physical and mental fatigue affect the same region of your brain—the anterior cingulate cortex. If that part of your brain is broadcasting “my brain is fried” signals at the end of the day, then it’s likely your muscles will be tired even before you head for the gym.
Exercising after the occasional harrowing day is unavoidable, but if you are chronically stressed, you could be seriously derailing your fitness goals. A new study in the Journal of Sport and Exercise Psychology found that mental burnout significantly affected physical performance.
Runners were intentionally stressed by being forced to complete a difficult computer test immediately before a 1.86-mile race (3,000-meters). The race times for runners who had taken the test were about 15 seconds slower than for the runners who hadn’t taken it.
But the deleterious effects of stress are actually farther reaching. In this article, we will review 10 ways stress can sabotage your fitness efforts. If you walk around in a semi-permanent state of overwhelm, perhaps your next workout should consist of several rounds of high-intensity stress management—instead of crunches or curls!
1. Stress Impairs Working Memory
Stress affects the part of your brain that deals with both short-term and long-term memory, and “working memory.” Working memory is what you use when you must consider multiple pieces of information at once (e.g. decision-making).
The process of thinking, perceiving, and evaluating requires your brain to have processing power—much like a computer. The more stress there is in the background, the less processing speed you will have at any given time.
If your working memory is impaired, as it is with chronic stress, even the simplest tasks become difficult, and athletic performance is no exception.
Whether you are an elite athlete or just engaging in a routine exercise class, if your brain is struggling to process information, then you’ll fatigue more quickly—mentally and physically. Making matters worse, when your stress levels are high, impulsivity typically trumps patience, which is not helpful at the gym or anywhere else.
2. Stress Sabotages Concentration
High levels of stress have been shown to negatively affect most aspects of human cognition and perception, including concentration and mental focus. There are two types of attention: external and internal. When you’re stressed, you are preoccupied with the source of the stress (internal focus), so you have fewer resources available for the task at hand (external focus).
Take golf, for example. Accurate perception and the ability to pay attention are key to a successful game. But if stress begins to interfere with your focus, your golf game is bound to suffer. There is probably no better example of this than Tiger Woods, whose PGA rank plummeted after his scandalous affair and the resulting media frenzy—undoubtedly related to the major stress he experienced during that period of time.
3. Stress Impairs Motor Coordination
Stress has been scientifically shown to impair motor control and coordination because it interferes with information processing in your cerebellum, the area of your brain responsible for these functions.
Research published in the Journal of Neuroscience showed that even a single exposure to acute stress affects information processing in your cerebellum. Stress is often accompanied by increased muscle tension, which can impede physical performance, increase your risk for injury, and slow down tissue repair.
4. Stress Compromises Visual Acuity
Stress can even interfere with your visual acuity and perception. High stress has been linked with everything from simple eye twitches to temporary blindness. Because your eyes work so closely with your brain, elevated cortisol has negative effects on the way you see things and process visual cues. With chronic stress, your adrenaline level stays elevated, potentially causing pressure in your eyes, distorted or blurred vision, tunnel vision, and eye strain. When stressed, your pupils dilate and the muscles around your face tighten, which constricts the blood vessels feeding your eyes. This then contributes to eye strain, headaches, and decreased visual acuity.
5. Stress Hampers Your Fitness Gains
If your stress level is high, you may not reach your fitness goals as quickly, as Finnish researchers recently discovered. According to Huffington Post:
“When you stick to a gym schedule, your muscles, heart and lungs adapt over time, making you fitter and stronger. One way experts measure this increase in fitness is by testing your VO2 max, how much oxygen your body uses during a workout. When Finnish researchers monitored 44 people starting a new cycling regimen, those who rated their stress levels highest saw the least improvement in VO2 max in a two-week period, despite doing the same workouts as everyone else.”
6. Stress Slows Exercise Recovery
Exercise itself is a form of stress, which triggers changes that make your body stronger. But the system breaks down if you are chronically stressed, as chronic stress impairs your body’s ability to respond to acute stress—such as exercise—because its resources are essentially used up.
A Yale study involving undergraduate students demonstrates how people with chronic stress take longer to recuperate from one high-impact exercise session. Stress levels were assessed using a psychological tool. An hour after the workout using heavy leg weights, the students with the lowest stress levels had regained 60 percent of their leg strength, whereas the high-stress students had regained only 38 percent.
Researchers attributed the difference to higher levels of cortisol and other stress chemicals, which affect your body’s rate of repair. They also postulated that the higher-stress students might have been getting inadequate sleep, eating poorly, and generally neglecting basic self-care, which would have compromised their bodies’ repair processes.
Similar results were found in a Journal of Strength and Conditioning Research study, in which individuals with higher stress felt more tired and sore 24 hours after a tough workout than individuals feeling less stressed. These studies and others confirm that microscopic cellular processes that repair damage within your body are mediated by your state of mind. So if you’re stressed, recovery from exercise will take longer—because so little is left in your tank for repair and recovery. In the words of Dr. Lissa Rankin, author of Mind Over Medicine:
“Our bodies know how to fix broken proteins, kill cancer cells, retard aging, and fight infection. They even know how to heal ulcers, make skin lesions disappear and knit together broken bones. But here’s the kicker—those natural self-repair mechanisms don’t work if you’re stressed!”
7. Stress Raises Your Risk for Injury
Another downside to exercising under stress is that you’re more likely to hurt yourself. Research has shown that a high degree of major life stresses (moving, divorce, death of a family member, etc.) or a high amount of daily hassles (getting a flat tire or a speeding ticket, losing your cell phone, etc.) can increase your risk for exercise injury. This is thought to result from attentional deficits and increased muscle tension.
“Past research has seen the relationship between athletic injuries and psychological factors as essentially stress-related. In this sense, stress is predicted to produce increased state anxiety and consequently alterations in attentional focus and muscular tension… Stress can cause attentional narrowing which results in important peripheral cues being missed.”