Influence of Immune and Nutritional Biomarkers on Illness Risk During Interval Training

Abstract

Intensive training periods may negatively influence immune function, but the immunological consequences of specific high-intensity-training (HIT) prescriptions are not well defined. Purpose: To explore whether 3 different HIT prescriptions influence multiple health-related biomarkers and whether biomarker responses to HIT were associated with upper-respiratory-illness (URI) risk. Methods: Twenty-five male cyclists and triathletes were randomized to 3 HIT groups and completed 12 HIT sessions over 4 wk. Peak oxygen consumption () was determined using an incremental cycling protocol, while resting serum biomarkers (cortisol, testosterone, 25[OH]D, and ferritin), salivary immunoglobulin-A (s-IgA), and energy availability (EA) were assessed before and after the training intervention. Participants self-reported upper-respiratory symptoms during the intervention, and episodes of URI were identified retrospectively. Results: Fourteen athletes reported URIs, but there were no differences in incidence, duration, or severity between groups. Increased risk of URI was associated with higher s-IgA secretion rates (odds ratio = 0.90, 90% confidence interval 0.83–0.97). Lower preintervention cortisol and higher EA predicted a 4% increase in URI duration. Participants with higher reported higher total symptom scores (incidence rate ratio = 1.07, 90% confidence interval 1.01–1.13). Conclusions: Although multiple biomarkers were weakly associated with risk of URI, the direction of associations between s-IgA, cortisol, EA, and URI risk were inverse to previous observations and physiological rationale. There was a cluster of URIs in the first week of the training intervention, but no samples were collected at this time point. Future studies should incorporate more-frequent sample time points, especially around the onset of new training regimens, and include athletes with suspected or known nutritional deficiencies.

Screening for Low Energy Availability in Male Athletes: Attempted Validation of LEAM-Q

“…Indeed, a recent review of the complex relationship between nutrition and immune tolerance/resistance has recently proposed that energy restriction per se may not increase illness risk, and that previous associations reported in studies of athletic populations may be mediated by a common co-morbidity such as higher ratings of psychological stress [100]. Indeed, one study has reported an apparent disconnect between EA and the occurrence of upper respiratory infections in athletes who commenced high-intensity interval training [101]. Further research on this theme is warranted.…”

Risk factors associated with acute respiratory illnesses in athletes: a systematic review by a subgroup of the IOC consensus on ‘acute respiratory illness in the athlete’

“…There was some evidence of increased risk of ARill and ARinf in endurance athletes and runners specifically. There was a lower risk of prolonged ARill (symptom days) for elite athletes 27–29. One study hypothesised that the individual training load threshold, above which the risk of illness increases,30 is lower in national level athletes than in international athletes.…”

H″IT″ting the Barriers for Exercising during Social Isolation

“…Therefore, some strategies might be used to alleviate this responses, like to reduce the duration of the sprints to less than 15 s [ 95 , 96 , 97 ], reduce the number of sprints [ 95 , 98 ], increase rest duration and perform active rest between sprints [ 99 ] or reduce weekly training frequency [ 100 ]. Moreover, caution should be taken with training schedule and weekly volume since consecutive days of two daily IT sessions induce acute immunosuppression and increased risk for infection [ 101 , 102 ].…”