The Effects of Exercise on Immunity

Key Points Exercise improves health and immunityOvertraining can reduce immunity though and make us more prone to infectionsIt is also important to take in enough total energy (‘fuel’) to preserve and improve immune function along with exercise It is widely accepted that exercise improves health and is, by extension, a valuable contributor to proper immune functioning and resistance to infection. However, excessive exercise is a stressor that can dampen immune functions and as a result, over-training can lead to increased rates of infection with colds and flu-like viruses, a situation commonly seen in athletes. Over-exercise or over-stress from any cause is pro-inflammatory and over half of all sports injuries are also secondary to overuse.1 Markers of antioxidant status such as glutathione concentration and inflammatory markers such as interleukin 10 are affected by long periods of intense training.2 So, exercise helps to mitigate stress and fatigue and helps us to modulate inflammatory/immune and antioxidant pathways, BUT too much (over-reaching) can be just as detrimental as too little. Overreaching and over-training syndrome in athletes is depicted as a continuum, this is also likely to be the case for generalised ‘stress’. So, excessive exercise (or any other stressor) can be thought of as stress, leading to fatigue, leading to a greater incidence of infection (and burnout). Excessive exercise (or any other stressor) can be thought of as stress, leading to fatigue, leading to a greater incidence of infection Moderate amounts of exercise improve immune system functions and reduce the risk of infection. On…

The Effects of Stress on Immunity

Key Points Stress has a significant impact on immunityJob stress and burnout are implicated in reducing immunityParticularly the amount of reward you receive for your efforts is a major factor in how stressed you become and the impact of this on immunityMeditation & mindfulness, and exercise reduce stress and improve immunity Stress has an undeniable and large effect on health and is a less commonly discussed, but extremely important part of encouraging the greatest human resilience and resistance to infections. A systematic review of 56 studies showed that stress had a significant impact on measures of immunity (reduced natural killer cell activity, NK and T cell subsets, CD4+/CD8+ ratio, and increased inflammatory markers). Stress has a significant impact on measures of immunity In particular, the following psychosocial factors of stress were implicated1: Job-stressLow job controlHigh job strainJob dissatisfactionHigh effort and low reward work OvercommittingBurnoutUnemploymentOrganizational downsizingEconomic recession The effort-reward imbalance, in other words, the reward you receive in comparison to the effort required at work, is particularly associated with much higher stress levels, with a demonstrable effect on immunity. Overcommitment or overwork are also associated with reduced immunity. For example, caregivers of dementia patients suffer poorer immune responses and this is considered to be as a result of the demands of their workplace stress,2 but a lower reward-to-effort ratio results in a greater reduction in immunity than over-commitment.3 A lower reward-to-effort ratio results in a greater reduction in immunity than over-commitment Prenatal stress is also reported to increase the risk of…

The Effects of Sleep on Immunity

Key Points Sleeping too little or too much are associated with impaired immunity and increased inflammationPoor quality sleep is also likely to worsen immune function It is likely that sleeping too little, or having poor sleep, and possibly sleeping too long impact immunity. There are strong associations between sleep length and quality and a range of long-term health outcomes, such as1: Diabetes mellitus Hypertension Cardiovascular diseasesCoronary heart diseases Obesity Over 70 studies featuring more than 50000 participants have evaluated the effects of sleep deprivation on markers of immunity and inflammation. Sleep disturbance was associated with higher levels of c-reactive protein, and the inflammatory cytokine interleukin 6 (IL-6). Shorter sleep duration was associated with higher levels of c-reactive protein, but not IL-6. Long sleep durations (>9 hours) were also associated with increased inflammation marked by higher c-reactive protein, and IL-6. Interestingly, neither long nor short sleep or sleep disturbance were associated with increased levels of tumour necrosis factor-α, one of the key markers of autoimmune inflammatory conditions like Crohn’s disease.2 C-reactive protein in particular also has an association with over-reaching and over-training in athletes, who also experience frequent colds and flu-like viruses and excessive stress-markers like this suppress some of the normal immune responses. Poor-quality sleep reduces our ability to properly modulate our immune function. In summary, poor-quality sleep reduces our ability to properly modulate our immune function. References 1.         Itani O, Jike M, Watanabe N, Kaneita Y. Short sleep duration and health outcomes: a systematic review, meta-analysis, and meta-regression. Sleep…