Exercise & Immunity

Experience From - Hank Garretson , Douglas Spink#1 , Jay Hodde#1 , Rich Schick , Douglas Spink#2 , Douglas Spink#3 , Jay Hodde#2 , Dr. Bill Misner Ph.D.

Quoted from 4 December Penn State Sports Medicine Newsletter:

David Nieman, Dr.P.H., Professor of Health and Exercise Science at Appalachian State University in North Carolina, is one of the world's leading authorities on exercise and immunity. He offered the Newsletter these observations.

"More than ever, we are seeing that heavy exertion of 90 minutes (running at a marathon pace, for example) or longer can suppress many parts of the immune system. Some of these functions are negatively affected for a few hours; others for a few days. But athletes are not going to stop intensive, long workouts. They will want to know what to do about the effect of heavy exercise on immunity. On-going research indicates that drinking sufficient carbohydrates (one liter per hour) during exercise slows the rise of stress hormones and offsets many of the negative immune responses. At this point, we do not know of anything better than carbohydrates to counter the suppression of immunity. Contrary to what has been written, there is no evidence that vitamin C has any positive effect." (See below.)

"At the other end of the spectrum," continues Nieman, "it appears that moderate activity is associated with beneficial changes in the immune function. Many of the changes are transient. They may exist during a bout of exercise and could be gone within a few hours. However, when moderate exercise is repeated on a near-daily basis, there is a cumulative effect that results in an improvement in protection of the exerciser. For example, people who engage in daily walks of 40-45 minutes at a pace fast enough to reach 70-75% of their maximum heart rate have half as many days when they suffer from colds or sore throats as do people who do not participate in an exercise program."

Vitamin C and Immunity

According to a study reported in the International Journal of Sport Nutrition, supplementing the diet with vitamin C has no effect on the immune system of distance runners. Twelve marathon athletes were randomly placed into a group that took 1,000 mg/day of vitamin C for eight days or into a group that was given a placebo for the same period of time. The subjects then ran at 75-80% VO2max for 2.5 hours. Blood samples were taken before and six hours after the run to measure a variety of hormones and immune variables. There was no significant effect of vitamin C on any of the measures.

Hank Garretson wrote:

"More than ever, we are seeing that heavy exertion of 90 minutes (running at a marathon pace, for example) or longer can suppress many parts of the immune system. Some of these functions are negatively affected for a few hours; others for a few days."

"But athletes are not going to stop intensive, long workouts. They will want to know what to do about the effect of heavy exercise on immunity. On-going research indicates that drinking sufficient carbohydrates (one liter per hour) during exercise slows the rise of stress hormones and offsets many of the negative immune responses."

Interesting study, but frankly my own experience is that regular, heavy physical exertion is just about the best thing I can do to prevent colds, flus, and other nasties. The worst problems I've ever had with such things occurred when I was desk-bound or traveling on business a great deal and NOT exercising at all.

The unfortunate thing about this kind of research is that it tends to reinforce the "couch potato" theory of "exercise is bad for your body." It would take one hell of a well-structured study to convice me that my immune system is better off doing a 45 minute, easy walk every few days versus going out and busting my ass on the trails a few times per week, balls to the wall.

In reference to the posts on exercise and immunity, I offer the following reports from different authors on this subject. By no means is this all-inclusive, as a medline search on "exercise and immunity" returns almost 200 articles written in the 1990's alone.

I'm particularly interested in this research right now as everyone I've talked to since my mono diagnosis last week has told me "it's due to all the running." Well, in my searches, I've found no specific link to the incidence of mono and exercise. Most of the reseach into exercise and immunity mentions the increased incidence of upper respiratory tract infections in endurance exercisers, and nothing more (interesting note: the immunosuppression is transient, lasting only for a few days after the run).

But that doesn't mean a link between exercise and mono doesn't exist. In fact, the NK cell suppresion mentioned below may very well be the link. But does that prove that I got mono as a result of the running? Nope. Is there a possible link? Yep. Given an incubation period of mono from 7 days to as long as 4 weeks, and given the immunosuppression that likely occurred after my runs at Quivering Quads & Kentucky, any run-in with the virus during November or December could have given the virus the ability to take hold on me and establish itself. Oh well, it happens.

I was able to run today (3 miles!) for the first time in 2-1/2 weeks. Just going slow and steady, biding my time and recovery in order to be ready for my 100-miler season which is set to begin on May 9-10 at Massanutten!

Here is some recent research on the subject of exercise and immunity:

Bruunsgaard H, et al. (Med Sci Sports Exerc 1997 Sep;29(9):1176-1181) says, "the in vivo cell-mediated immunity was impaired in the first days after prolonged, high intensity exercise [1/2 IRONMAN], whereas there was no impairment of the in vivo antibody production measured 2 wk" later.

Steerenberg PA, et al. (Eur J Oral Sci 1997 Aug;105(4):305-309) concludes, "the exercise of a [OLYMPIC DISTANCE] triathlon may decrease the level of IgA-mediated immune protection at the mucosal surface. As triathletes may during the race be exposed to micro-organisms present in the swimming water, a decreased IgA-mediated immunity during the race may pose triathletes at an increased risk of infections."

Venkatraman JT, et al. (Med Sci Sports Exerc 1997 Mar;29(3):333-344) writes, "This study indicates that short, intense bouts of exercise in runners training 40 miles/wk have mixed effects on the immune system. A high percentage of fat intake (41%) did not have any deleterious effects on the immune system of the well-trained runners."

Nieman DC. (Int J Sports Med 1997 Mar;18 Suppl 1:S91-S100), in a review article writes [ABSTRACT REPRINTED IN ITS ENTIRETY]: "During the last 95 years, 629 papers (60% in the 1990s) dealing specifically with exercise and immunology have been published. Major findings of practical importance in terms of public health and athletic endeavor include: (a) In response to acute exercise (the most frequently studied area of exercise immunology), a rapid interchange of immune cells between peripheral lymphoid tissues and the circulation occurs. The response depends on many factors, including the intensity, duration, and mode of exercise, concentrations of hormones and cytokines, change in body temperature, blood flow, hydration status, and body position. Of all immune cells, natural killer (NK) cells, neutrophils, and macrophages (of the innate immune system) appear to be most responsive to the effects of acute exercise, both in terms of numbers and function. In general, acute exercise bouts of moderate duration (< 60 min) and intensity (< 60% VO2max) are associated with fewer perturbations and less stress to the immune system than are prolonged, high-intensity sessions. (b) In response to long-term exercise training, the only finding to date reported with some congruity between investigators is a significant elevation in NK cell activity. Changes in the function of neutrophils, macrophages, and T and B cells in response to training have been reported inconsistently, but there is some indication that neutrophil function is suppressed during periods of heavy training. (c) Limited data suggest that unusually heavy acute or chronic exercise may increase the risk of upper respiratory tract infection (URTI), while regular moderate physical activity may reduce URTI symptomatology. (d) Work performance tends to diminish with most systemic infectious, and clinical case studies and animal data suggest that infection severity, relapse, and myocarditis may result when patients exercise vigorously. (e) Although regular exercise has many benefits for HIV-infected individuals, helper T cell counts and other immune measures are not enhanced significantly. (f) Data suggest that the incidence and mortality rates for certain types of cancer are lower among active subjects. The role of the immune system may be limited, however, depending on the sensitivity of the specific tumor to cytolysis, the stage of cancer, the type of exercise program, and many other complex factors. (g) As individuals age, they experience a decline in most cell-mediated and humoral immune responses. Two human studies suggest that immune function is superior in highly conditioned versus sedentary elderly subjects. (h) Mental stress, undernourishment, quick weight loss, and improper hygiene have each been associated with impaired immunity. Athletes who are undergoing heavy training regimens should realize that each of these factors has the potential to compound the effect that exercise stress is having on their immune systems."

Peters-Futre EM. (Exerc Immunol Rev 1997;3:32-52), writes: "Clinical manifestation of reduced neutrophil function following participation in ultramarathon races has, however, not been observed. Although neutrophils constitute 50-60% of leukocytes and although they are the first line of defense to bacteriological invasion, postrace episodes of upper respiratory tract infection (URTI) are not correlated with a decrement in the function of this individual parameter of immune function. The efficacy of Vitamin C supplements in reducing the incidence of postrace URTI symptoms, therefore, cannot be fully explained at this stage."

Pedersen BK, et al. (J Sports Med Phys Fitness 1996 Dec;36(4):236-245) writes, "it has become clear that the immune system responds to increased physical activity and may be given some of the credit for exercise-related reduction in illness. In contrast, it has repeatedly been shown that intense exercise causes immunosuppression. In essence the immune system is enhanced during moderate and severe exercise, and only intense long-duration exercise is followed by immunodepression. The latter include suppressed concentration of lymphocytes, suppressed natural killer and lymphokine activated killer cytotoxicity and secretory IgA in mucosa. Whether or not the "open window" in the immune system occurs is dependent on the intensity and duration of exercise. One reason for the "overtraining effect" seen in elite athletes could be that this window of opportunism for pathogens is longer and the degree of immunosuppression more pronounced."

The research on the subject is interesting but I have found over the years that ultra runners don't seem to have much down time due to illness. I find that I am sick less often than my family and non-running friends despite the fact that I spend all day examining sick people. I would be more interested in a study looking at actual rates of illnesses both viral and bacterial in endurance athletes looked at both from the annual incidence and in the two week post competition period. This to be compared to sedentary controls.

The occurrence of illness is not simply a matter of cell mediated immunity, it is a much more complicated system which is not completely understood. While exercise may negatively influence on factor it may offset this with salutary effects on another factor. Another thought is the dip in cellular immunity might be an equivalent of sore muscles after a workout - an applied stress causing minor damage that stimulates the body to strengthen itself.

Rich Schick wrote:

"The occurrence of illness is not simply a matter of cell mediated immunity, it is a much more complicated system which is not completely understood. While exercise may negatively influence on factor it may offset this with salutary effects on another factor. Another thought is the dip in cellular immunity might be an equivalent of sore muscles after a workout - an applied stress causing minor damage that stimulates the body to strengthen itself."

Rich's point re the difference between measuring levels of certain elements versus measuring actual incidence of sickness is also well taken. I simply don't know any frequent runners who are always sick; quite the reverse, actually.

Nick Williams wrote:

"I am extremely interested in the last few messages I have seen regarding exercise and Immunity. I have been running ultras since 1987 and 2+ years ago I started having body aches, extreme exhaustion, lowered temperature (95 to 97 degrees), and just flu like symptoms. I have continued to run ultras and have finished two 100's and several 50 mile and 50K races. I DNF'D at Hardrock 2 times, and Barkley 2 times since. I have stopped running one more time until the aches and exhaustion leaves, or at least backs off. I have really backed of on the running I have done, trying to get well."

Here's some thoughts:

1. Overtraining, which you have already mentioned. Are you giving your body enough time to recover after workouts? Are you still sore from the last run when you go out for the next one?

2. Protein: are you eating enough good-quality protein to fuel your muscular recovery? Are you eating it right after workouts to prevent catabolic breakdown of muscle tissue and speed recovery?

3. Sleep: getting enough? I've found that when I am training at 100% effort levels, I absolutely need 8 hours per night of good sleep. If I am being lazy and not training, I can sneak by with less. Sleep is the best recovery-booster there is.

4. Eating enough? If you aren't taking in enough calories overall, you could see symptoms like you describe. In our diet-crazy culture, we are sometimes subsconsciously guilty when eating good quantities of good food. Someone training alot in the hills is going to, more likely than not, have trouble getting *enough* calories just to break even. If you aren't taking enough in to make up for your output, your body will eventually start digesting itself, muscle and all (most runners have little fat reserves to fall back on, unlike the average American, so muscle is the first to go). Not a pleasant experience.

Doug wrote:

"Rich's point re the difference between measuring levels of certain elements versus measuring actual incidence of sickness is also well taken. I simply don't know any frequent runners who are always sick; quite the reverse, actually."

So what is done instead? Researchers take the incidence of illness in marathon runners, for example, and then run a controlled study to look at a specific variable (such as IgA levels). Then they try to say that the two are related.

Not the best science, but it's all that's out there.

There are way too many other variables to take into consideration to make any concrete judgements. As one of the abstracts I reprinted yesterday said, the only agreement between studies appears to be that IgA levels are depressed following intense endurance exercise. There was no mention of how that relates to disease.

In my case, I was sick (upper respiratory infection) back in May for 4 days, but prior to that, I had been illness-free since I began running. This latest setback, I'm sure, is more related to diet patterns, lack of sleep, and increased emotional stress, than it is to my running mileage -- even with the high-mileage year I've had.

There are many markers indicating optimal immune-response. One of these agents is interferon. Interferons are simply proteins which are associated with anti-viral activity.

Pauling, a nobel laureate, has a verified study of record(1970) that shows increasing Vitamin C leads to a significantly larger production of interferons.

Vitamin C inhibits the synthesis of prostaglandins PGE2 and PGF2-alpha, which are directly involved in the inflammatory response to damaged cells after exercise.(Horobin 1978)

Vitamin C intake has also been shown in the laboratory of Horrobin, Oka and Manku(1979) to increase the synthesis of Prostaglandin PGE1's, assisting in the formation of lymphocytes, which play a major role in immune responses.

While I have listed only 2 immune system markers and have neglected the issue of post-exercise free radical scavenging by know antioxidants such as Vitamin C, there are literally dozens of other "Markers" that could be discussed in favor of supplementing with Vitamin C before and after endurance activities.

The use of Dr. Nieman's comments in relation to the immune response to exercise are severely limited to during exercise (or a few hours post), and not meant to imply that an ultrarunner should not take antioxidants.