Protective Roles of Exercise and Nutritional Factors for Immune System During Delta Variant-COVID-19 Outbreaks: Evidence Review and Practical Recommendations

The coronavirus disease 2019 (COVID-19) is a deadly viral infection causing death due to impaired immunity. Therefore, an investigation of factors affecting the immune system should be considered. It is well documented that regular sessions of moderate-intensity exercise training with up to 1-hour duration boost the immune functions through anti-inflammatory and antioxidant effects. Besides, a diet containing functional and nutritious foods is also needed to aid the immune system. Herein, we have summarized available data on how exercise and nutritional factors help promote immunity against various infections. More importantly, this review provides practical and valuable guidance for sedentary adult people and non-professional athletes on how to do aerobic and resistance training and stretching exercises at home with no special types of equipment required during the outbreaks of delta variant-COVID-19. Some significant exercise-related nutritional considerations regarding carbohydrates, fibers, vitamins, zinc, and omega-3 fatty acids were also supplied that help to create better adaptations and improve immune responses.