It may seem like the only way to improve your fitness level is to work harder, but research shows there is a way to get more results out of the work you are already doing. A new report from the European Society of Cardiology says by just incorporating a better diet you will improve your fitness level.

"This study provides some of the strongest and most rigorous data thus far to support the connection that better diets may lead to higher fitness," said study author Dr. Michael Mi of Beth Israel Deaconess Medical Center in Boston. "The improvement in fitness we observed in participants with better diets was similar to the effect of taking 4,000 more steps each day."

Cardiorespiratory fitness is one of the most powerful predictors of longevity and health and involves multiple organ systems such as the heart, lungs, blood vessels and muscles. It reflects the body’s ability to provide and use oxygen for exercise. And even though two people can do the same amount of work they may not have the same fitness level.

While it has many benefits, this study was designed to determine if a healthy diet had any impact on physical fitness. It involved nearly 2,500 individuals with an average age of 54 and it was pretty evenly distributed between males and females.

The participants completed a maximum effort exercise test on a stationary bike to measure peak VO2. That’s considered the best assessment for physical fitness as it indicates the amount of oxygen used during the highest possible intensity exercise.

The study participants also completed a comprehensive food-frequency questionnaire to determine how often they consumed the listed 126 items. Their individual diets were rated by using the Alternative Healthy Eating Index and the Mediterranean-style Diet Score. Both are measures of a heart-healthy diet that is higher in vegetables, fruits, whole grains, nuts legumes, fish and healthy fats while limiting red meat and alcohol.

Researchers then graded the participants based on their diet and VO2 scores and found those with better diets had greater peak VO2.

"In middle-aged adults, healthy dietary patterns were strongly and favorably associated with fitness even after taking habitual activity levels into account," Dr. Mi said. "The relationship was similar in women and men, and more pronounced in those under 54 years of age compared to older adults."

Researchers went a step further and looked at the connection between diet, fitness and metabolites, which are substances released into the blood during exercise that are produced during digestion.

"Our metabolite data suggest that eating healthily is associated with better metabolic health, which could be one possible way that it leads to improved fitness and ability to exercise," Dr. Mi said. "There are already many compelling health reasons to consume a high-quality diet, and we provide yet another one with its association with fitness. A Mediterranean-style diet with fresh, whole foods and minimal processed foods, red meat and alcohol is a great place to start."

Click here to read more in the European Journal of Preventative Cardiology.