We've known for a while now that exercise is good for you. It’s good for everything from strengthening your body to increasing your mood to helping you sleep better. With all that said, is it possible to get too much of a good thing?

Let's turn to Dr. Michael Murry to discover the proper dosage for all you joggers out there.. 

Background Data:
 

Regular exercise protects against the development of CVD and also favorably modifies other CVD risk factors including high blood pressure, blood lipid levels, insulin resistance, and obesity. Exercise is also important in the treatment and management of patients with CVD or increased risk including those who have hypertension, stable angina, a prior heart attack, peripheral vascular disease, heart failure or are recovering from a cardiovascular event.

Despite the benefits of exercise, throughout history there have been reports of people dying from running too much or too far. The most famous case is that of Pheidippides, a running courier who in 490 B.C. is believed to have run from Marathon to Athens, Greece, a distance of approximately 25 miles, to bring news of the Athenian victory over the Persians. Upon reaching the Athenian Agora, he exclaimed “Nike!” (“victory”), and then collapsed and died.

One of the most famous studies on the effect of exercise and jogging on heart health is the Copenhagen City Heart Study. One analysis of this study was performed in a random sample of 1,878 joggers who were followed for up to 35 years and compared with 16,827 non-joggers showed that the increase in survival among joggers was 6.2 years in men and 5.6 years in women. This particular analysis also indicated that jogging up to 2.5 hour per week at a slow or average pace and a frequency of ≤3 times per week was associated with the lowest mortality. Those who jogged >4 hours per week, at a fast pace, and >3 times per week appeared to lose many of the longevity benefits noted with less strenuous doses of jogging. These findings were not entirely unexpected by the researchers as some other studies had shown that excessive exercise was just as bad for the heart as too little.
 

New Data:
 

In an effort to better evaluate the ideal dosage of jogging to improve longevity, researchers looked at a different set of data from the Copenhagen City Heart Study that used 1,098 healthy joggers and 3,950 healthy non-joggers being followed up since 2001. The aim of this study was to investigate the association between jogging and long-term, all-cause mortality by focusing specifically on the effects of pace, quantity, and frequency of jogging.

The joggers were divided into light, moderate, and strenuous joggers. Light joggers had a slow or average pace, approximately 5 miles per hour, <2.5 hours of jogging per week with a frequency of ≤3 times per week. Moderate joggers had a slow or average pace, ≥2.5 hours of jogging per week with a frequency of ≤3 times per week or fast pace, ≤4 hours of jogging per week with a frequency of ≤3 times per week or slow or average pace with a frequency of >3 times per week or fast pace, <2.5 hours of jogging per week with a frequency of >3 times per week. Strenuous joggers had a fast pace of more than 7 miles per hour and either >4 hours of jogging per week or ≥2.5 hours of jogging per week with a frequency of >3 times per week.

Compared with sedentary non-joggers, 1 to 2.4 hours of jogging per week was associated with the lowest mortality (71% reduction in risk). The optimal frequency of jogging was 2 to 3 times per week (68% reduction in risk) or less than 1 time per week (71% reduction in risk). The optimal pace was slow (49% reduction in risk) or average (62% reduction in risk).

The highest reduction in risk for mortality was found in light joggers (78%) followed by moderate joggers (34%). The strenuous joggers actually showed a mortality rate that was not statistically different from that of the sedentary group.

Commentary:

As someone that is extremely active and believes in the value of regular exercise, this study on the surface seems to go against that practice. However, as usual in these types of studies, there is more to the story. What do we really know about the value of exercise in the promotion of health? Quite a lot actually and there is significant value with regular exercise, but excessive exercise may be quite harmful as this study suggest.

First, higher intensity and dosages of exercise is associated with many health benefits including improved cardiovascular and respiratory function, reduced body fat percentage and in particular reduced abdominal adiposity (belly fat), improved blood sugar control, and better cholesterol levels. Exercise intensity may also improve mood, sleep, and self-esteem in a dose-dependent manner. So, this study does not represent the end-all in terms of evaluating the effects of exercise on longevity.

Other studies that have looked at exercise have also reported this U-shaped curve showing that too much exercise had the same risk of early mortality as too little exercise. In terms of running, it was suggested that the limit of health benefits started to erode when people started running more than 35 miles per week or walking more than 46 miles per week.
 

It is thought that the detrimental effects of excessive exercise are due to the fact that exercise promotes inflammation and oxidative damage. Yep, the very things linked to hardening of the arteries (atherosclerosis). However, a little dosage of exercise stimulates the body to produce anti-inflammatory and antioxidant substance. That is a great thing, but at an excessive dosage exercise may lead to damage to the heart and blood vessels in a way that accelerates heart disease and hardening of the arteries.

So, what to do? You love your workouts and don’t want to give it up, right? Here are a few tips on how to protect yourself from the "cons" of exercise, while still reaping the pros!

1. Get PLENTY of sleep, REST and RECOVER

2. Maintain a healthy and well-balanced diet consisting of:

• Protein (animal sources = complete proteins, vegetarian sources = incomplete proteins)
• Complex Carbs (brown rice, buckwheat, quinoa, root vegetables, legumes)
• Essential Fatty Acids (EFA) (flax, hemp hearts, cold water fish, walnuts, pumpkin seeds)
• Antioxidant (AO) Rich Foods (An easy trick: eat a rainbow of food colours as each provides specific protection)
• Heart Health Promoting Foods (antioxidants, EFAs, cacao polyphenols)

3. Hydrate!

As soon as you realize you are thirsty, you are dehydrated! Aim for 2L of water per day, and an additional 500ml/hour of exercise.

4. Supplement When Necessary

Preventative measures: fish oil, theracurcmin, flavonoid-rich extracts, probiotic and others depending on the type of exercise and your specific lifestyle.

5. Swap one of your intensive workouts (such as running) for a GENTLE yoga class or nice outdoor WALK