10 Reasons Your Workout Is Great One Day But Lousy the Next

When it comes to working out, everyone has good days and bad days at the gym or on the trails. Running 10 miles may feel like 5 miles, or conversely, lifting 10 pounds may feel like 50 pounds. Either way, understanding what factors affect your exercise performance can help better prepare you for your workout, regardless of the circumstances.

We can’t stress the importance of enough sleep. According to the American College of Sports Medicine, lack of sleep can lead to weight gain, increased appetite, and lethargy—all detrimental to your workout. For top performance in the gym or on the trails, most doctors recommend between seven and nine hours of sleep per night. For race days or tough workouts, make sleep the night before a top priority.

Making smart food choices is essential to a successful workout. If you’re planning a tough morning session, avoid spicy foods the night before since they may upset your stomach. Before your workout, avoid high fiber foods, and stick to easily digestible options such as a banana or slice of toast with peanut butter.

An intense workout today can lead to tender and stiff muscles tomorrow. Known as Delayed Onset Muscle Soreness (DOMS), this is simply an inflammatory response to increased muscle exertion. Soreness subsides within a few days, but icing the affected area or a gentle yoga session can help speed up the process. Warming up properly beforehand and stretching afterwards can help prevent DOMS altogether.

Whether it’s a frustrating day at the office or your car decides to break down, bad days are sometimes unavoidable. A negative attitude can make your workout daunting, tempting you to skip it altogether. If at all possible, resist trying to relieve stress with a glass of wine and a mindless television show in place of a workout, as studies prove that exercise is one of the most effective ways to reduce stress.

In extreme heat, your body must work harder to cool itself, making you feel tired more quickly. A workout that feels easy in 50-degree weather may feel impossible in 90-degree weather. Vice versa, in sub-zero temperatures, your muscles are more likely to stiffen, making them easier to strain. Warming up properly in the cold, and making sure to stay hydrated in heat will set your workout up for success.

Performing the same exercises day after day causes your muscles to hit a plateau, making it harder to achieve fitness gains. According to the American College of Sports Medicine, a guaranteed way to break the monotony and keep your muscles engaged is to try a new exercise. If you’re lifting, increase your weight or swap free weights for a kettle bell. If you’re jogging, try a fartlek that involves a mix of faster and slower speeds. 

Dehydration causes your core temperature to rise faster, making it more difficult to exercise at a high intensity for a prolonged period of time. The Institute of Medicine recommends at least 3.7 liters of water for men and 2.7 liters for women, bearing in mind that water can also come from food such as cucumbers, tomatoes, and even cauliflower.

Because pavement pounding breaks down cushioning in shoes over time, many runners can experience foot pain during exercise. Experts recommend replacing your shoes every 300 to 500 miles of use—a range determined by factors such as stride and weight. Additionally, rotating between several pairs of running shoes extends their lifespan while working different muscles in your feet and lower legs.

Fail to stretch before and after your workout and your muscles are more likely to feel tight and stiff the next day. A tight muscle restricts your range of motion, making your body work harder during exercise. We recommend a yoga session or two each week, especially if you’re working out at a high intensity—it’s a great way to give your muscles the TLC they need to recover.

While fitness gains come from hard work, your body needs time to recover and repair itself. Consistently sore muscles and an overall feeling of fatigue every time you hit the gym may mean you have pushed yourself too far without adequate rest. Listen to your body, and take an extra day to recharge if needed—for example, if you’re a runner, cross train by biking or swimming to exercise different muscle groups.