Why Can Exercise Make You Irritable?

Much like excessive muscle soreness or sharp joint pain, that mental state is information your body is sending to tell you that you likely need to shift your habits, according to Rocky Snyder, CSCS, a strength and conditioning specialist in Santa Cruz, California, and author of strength training guide Return to Center.

“There are numerous potential reasons as to why you might leave your workout unhappy or cranky,” he says. “Keeping track of this reaction, along with variables like sleep, meals, and recovery time, can really help you get a true understanding of what's going on.”

Although it might take time, and some trial and error, to determine what's leading to your postworkout crankiness, Snyder says it's worth the effort because preventing it will help maintain your motivation.

Underfueling and Blood Sugar Crashes

One of the first things to think about when you’re irritable after exercise is what and how much you're eating, according to Cassandra Padula Burke, RDN, a triathlon coach and owner of Catalyst Nutrition & Performance in Westminster, Maryland.

“When you train without adequate carbohydrates, you ask your body to drive on empty,” she says. “That cranky feeling by the end of your session is your body running out of fuel.” That's the reason undereating in the sports world is called “underfueling” (also known as low energy availability).

• Nervousness and anxiety
• Confusion
• Irritability and impatience
• Lightheadedness
• Feeling jittery or shaking

The Overtraining Trap

Even if your nutrition is on point, you may be dealing with crankiness and irritability simply from training too frequently, too intensely, or both, without adequate recovery time.

According to Cleveland Clinic, overtraining isn't the same as feeling sore after a major workout or a few days of training — it's a medical condition that can lead to physical, mental, and emotional symptoms such as:

• Anxiety
• Unexpected weight loss or gain
• Irritability or agitation
• Feeling restless
• Unusually fast heartbeat
• Fatigue
• Depression
• Losing motivation to train or be active

“Crankiness is one of the many symptoms of overtraining,” says Snyder. “You may also notice yourself getting sick more often, struggling with sleep, seeing a loss of appetite, or experiencing reduced strength levels.”

Sleep Deprivation

Maybe you're taking adequate rest days and you've dialed in your nutrition, but you’re still feeling off after workouts. In that case, it's helpful to take a look at your sleep quality, says Burke.

“Poor sleep habits can contribute to post-training irritability,” she says.

“Heading into a training session when you’re already exhausted just amplifies your fatigue. Aim for seven to nine hours of quality sleep daily to support recovery. If you consistently get less than that, consider planning extra rest days into your training schedule or decrease the number of hard sessions you do each week.”

Keys to a Better Mood After Exercise

Working on the three most common culprits — underfueling, overtraining, and sleep challenges — can often go a long way in easing postworkout irritability.

With fueling, Burke recommends consuming carbohydrates 30 to 60 minutes before training, depending on duration and intensity.

“Toast with honey, pretzels, fruit snacks, or a sports drink will help fuel your performance and keep you from feeling ‘hangry’ by the end of your session,” she says. “For training sessions longer than 60 minutes, fuel during your session with 30 to 60 grams of carbs per hour. A preworkout snack plus carbs and protein within 30 to 45 minutes after will keep you from feeling irritable and support recovery.” Also be sure to rehydrate often, she adds.

Schedule rest days into your training program and stick to them, says Snyder. Recovery is just as important as what you do for exercise, and it should be treated as such, he says.

Along with that, monitor your sleep patterns to make sure you’re getting enough deep sleep, Snyder says. This can be done with a sleep tracker or fitness tracker, which can be a good investment if you think sleep might be scuttling your athletic performance and emotional health.

“Keeping a journal of not just your workout routine but also tracking your water consumption, sleep patterns, and meals can really help you avoid overtraining,” says Snyder. “Taking out the guesswork and getting a true understanding of your lifestyle will serve you well. Most people believe they are good in all of these categories until they put it down on paper.”

When to Talk to Your Doctor

If feeling irritable after workouts happens regularly despite fueling adequately and getting enough rest, or if you're experiencing other symptoms like extreme fatigue, sleep disturbances, decreased performance, or loss of appetite, consult a healthcare professional, suggests Burke.

“There may be other causes such as hormonal imbalances, a condition called relative energy deficiency in sport, or other underlying issues that require professional assessment,” she says.

It’s always a good idea to talk to your doctor before you start a new workout program.

The Takeaway

• Much like muscle pain or joint aches, exercise-induced irritability can be a signal from your body that training needs to change.
• The main culprits for postworkout irritation include underfueling that leads to low blood sugar, inadequate recovery time, and sleep difficulties.
• If you dial in your nutrition, take more rest days, and improve your sleep but you're still struggling with irritation, talk to your doctor to identify possible underlying issues.