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Nutrition, Exercise And Lifestyle Advice To Support Your Clients Immune System

The role of the immune system is to fight off infection and disease from germs and pathogens from outside the body. The two arms of the immune system work together to protect the body and keep it healthy. The innate arm provides general protection initially against a wide range of foreign organisms. The adaptive arm develops specific antibodies to protect us against target foreign antigens; thus, its response is delayed. 
 
In a previous article, we've outlined how "boosting" an immune system would be inadvisable, even if it was possible.

However, there are ways to support an immune system through nutritional choices and an appropriate physical activity regime.

 
Nutrition And The Immune System
Nutritional impacts on the immune system are studied from one of two camps: Overnutrition (obesity) and undernutrition (deficiencies in overall energy balance and macro- and micronutrient deficiencies). 
 
There hasn't been a great deal of research into obesity and the immune system, but some research does exist. One piece of research indicated that the chronic low-level inflammation associated with obesity could increase the risk of infection, particularly of the respiratory tract when compared with non-obese populations.
 
Undernutrition is problematic in as far as it causes dietary deficiencies which means that the immune system lacks support in directing resources. Immunodeficiency is more likely in some groups than others (people with eating disorders, smokers, the elderly).
 
In both cases, the most pragmatic suggestion to your personal training clients would be to remove nutritional deficiencies as a first step. Practically speaking, this means advising your clients about a well rounded, balanced diet - rich in protein, including fruits and vegetables.

Their portion size will depend on their body composition goals. If they need to lose weight, focusing on amounts that give them enough nutrients to support their daily activities but still keeping them in a calorie deficit so they can progress towards their goals. If your client is underweight and they want to gain weight, they will likely need to increase their portion sizes and potentially consider supplementation.
 
There are certain micronutrient deficiencies, such as iron, zinc and vitamin A, that do harm the immune system. In cases where your clients are unable or unwilling to address this through their diet, supplementation can help, and generally, a good quality multivitamin is advised. But be aware that a blanket approach to supplementation isn't recommended - and more isn't necessarily better.

Suppose you or your clients suspect that they might be deficient in specific nutrients. In that case, your responsibility is to advise them to get it tested first and once it's confirmed, follow the advice of their practitioner or a registered dietitian. In some cases, medical intervention and or a prescribed diet plan may be needed, and that's beyond a personal trainer's scope.


Exercise And The Immune System
There has been a lot of research into the impact of moderate activity on the immune system. Much of the research has focused specifically on upper respiratory tract infections (URTI). The findings indicate that a moderately active person is less likely to contract an upper respiratory tract infection than both someone who is mostly sedentary, and also people who engage in strenuous endurance exercise regularly.
 
The effect is particularly pronounced in older adults and obese people. The research also demonstrated that 12-15 weeks of moderate exercise (e.g., 30-45 minutes at 60% to 75% heart rate reserve, five times per week) resulted in 
lower incidence or duration of URTI compared to sedentary individuals. 
 
Based on a wide range of scientific data, the general evidence seems to be that regular, moderate-intensity aerobic activity (3-5 times per week, 30-45 minutes) could be suggested to personal training clients as a preventative strategy to make their immune systems more robust. The extent to which it will support their immune system will be dependant on the individual. 
 
The effects of resistance training are less thoroughly studied with regards to resistance to infection specifically. Therefore, supporting your personal training clients with an exercise regime need not include low volume, high-intensity resistance training. 
 
It's advisable that if they are unused to training this way, returning to exercise with moderate intensity will likely serve their health better since the adaptation of the immune system to physical activity seems to be dependent on the duration, intensity, and type of exertion.
 

Lifestyle And The Immune System
General health markers are improved when clients stop smoking - especially when considering upper respiratory tract infections. Client health is improved, and their immune systems are well supported when they reduce alcohol intake to a moderate or low level. 
 
Probably one of the biggest problems for the immune system is chronic, long term stress. Extensive research into the impact of stress indicates the extent of the damage it can do to the immune system, making people who are chronically stressed more susceptible to everything from the common cold to extending the amount of time it takes to heal from a wound. As much as possible, clients should be supported to avoid stress - and strategies to limit stress responses, such as walking in the fresh air, reading for enjoyment or meditating could be planned together.
 
Getting enough good quality rest, and sleep will be a crucial element in maintaining a healthy and robust immune system. Sleep deprivation is an immune suppressant and a stress factor. Long term sleep problems increase the amount of chronic stress on the body adding to other stressors like work, family and even physical activity.

You might support your clients by planning some ways they might improve their sleep quality. Advice may include sleeping in a fully dark room with blackout curtains, limiting or removing screens and blue light before bedtime, and keeping their bedrooms cool. The amount of sleep they need is recommended between 7-9 hours.


Conclusions
The take-home message from the scientific evidence for personal trainers who are looking to support their clients' immune systems seems to be to do the basics consistently. 
 
Keep a balanced training regime which includes moderate amounts of aerobics and resistance training 3 to 5 times a week, for around 30 to 45 minutes. There's no need to train with high intensity or to introduce endurance training if the goal is general health. 
 
Including a variety of nutrient-dense foods in their diets, including high protein and a range of colourful vegetables and fruits will help to support the immune system by giving it the macro and micronutrients it needs. Avoiding nutrient deficiencies will be most important.
  
Helping your clients through practical guidance that supports their immune system will be vital if you work mostly with people whose goals relate to their general health and fitness. Medical advice is beyond the scope of practice of a personal trainer, though, and if your client is genuinely concerned about their health, you can always refer them to their doctor.
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