Pro inflammatory cytokine production by polymorphonuclear neutrophils following a 12-day period of intensified training

A thesis submitted to the University of Bedfordshire, in partial fulfilment of the requirements for the degree of Master of Science by Research.This thesis investigated whether resting and/or exercise-induced interleukin-8 (IL-8) and tumor necrosis factor-α (TNF-α) production by antigen-stimulated polymorphonuclear neutrophils (PMN) would alter over a 12-day intensified training period (ITP). Ten physically active males completed seventeen exercise sessions in total, including: two main trials (30-min self-paced treadmill run (RPETR), 10 km time trial), completed before (MTPRE) and after (MTPOST) a twelve day ITP, and two V̇O2max tests completed before (VO2PRE) and after (VO2POST) the ITP. Blood samples were collected via venepuncture before and after the RPETR at MTPRE and MTPOST. PMN were isolated from whole blood and incubated for 18 h with lipopolysaccharide (LPS) antigen. IL-8 and TNF-α production by LPS-stimulated PMN was determined using enzyme-linked immunosorbent assay (ELISA) tests. TNF-α production by LPS-stimulated PMN significantly elevated in response to the RPETR at MTPRE (P = 0.004) and MTPOST (P = 0.047). IL-8 production only significantly increased in response to the RPETR at MTPRE (P = 0.033) but not at MTPOST (P = 0.199). The absolute RPETR-induced increase in TNF-α and IL-8 concentrations by LPS-stimulated PMN were lower at MTPOST compared to MTPRE. Blood PMN concentration increased significantly following the completion of RPETR at MTPRE (P = 0.02) and MTPOST (P = 0.016). Resting and RPETR-induced blood PMN concentrations did not significantly differ between MTPRE and MTPOST (P = 0.521). Following the completion of the ITP, V̇O2max (P = 0.696) and 10 km time to completion scores (P = 0.457; d = 0.32) did not change. The severity of upper-respiratory tract symptoms (URTS) increased in six out of ten participants following the ITP. Self-reported general (P = 0.040) and sport-related (P = 0.005) stress scores were higher at MTPOST compared to MTPRE. The identification of increased stress states, more severe URTS, and decreased physical performance capacities in participants indicates that overreaching may have been achieved following the ITP. Reduced pro-inflammatory cytokine production in response to acute exercise following a period of intensified training may predispose athletes to impaired inflammatory responses during exercise which may contribute to the pathogenesis of reported URTS in athletes who are overtraining

Collagen peptide supplementation before bedtime reduces sleep fragmentation and improves cognitive function in physically active males with sleep complaints

Purpose: The primary aim of this study was to examine whether a glycine-rich collagen peptides (CP) supplement could enhance sleep quality in physically active men with self-reported sleep complaints. Methods: In a randomized, crossover design, 13 athletic males (age: 24 ± 4 years; training volume; 7 ± 3 h·wk1) with sleep complaints (Athens Insomnia Scale, 9 ± 2) consumed CP (15 g·day1) or a placebo control (CON) 1 h before bedtime for 7 nights. Sleep quality was measured with subjective sleep diaries and actigraphy for 7 nights; polysomnographic sleep and core temperature were recorded on night 7. Cognition, inflammation, and endocrine function were measured on night 7 and the following morning. Subjective sleepiness and fatigue were measured on all 7 nights. The intervention trials were separated by ≥7 days and preceded by a 7-night familiarisation trial. Results: Polysomnography showed less awakenings with CP than CON (21.3±9.7 vs. 29.3±13.8 counts, respectively; P=0.028). The 7-day average for subjective awakenings were less with CP vs. CON (1.3±1.5 vs. 1.9±0.6 counts, respectively; P=0.023). The proportion of correct responses on the baseline Stroop cognitive test were higher with CP than CON (1.0±0.00 vs. 0.97±0.05 AU, respectively; P=0.009) the morning after night 7. There were no trial differences in core temperature, endocrine function, inflammation, subjective sleepiness, fatigue and sleep quality, or other measures of cognitive function or sleep (P>0.05). Conclusion: CP supplementation did not influence sleep quantity, latency, or efficiency, but reduced awakenings and improved cognitive function in physically active males with sleep complaints

The effect of exercise and nutritional interventions on promoting adaptations to redox signalling

The effect of exercise and nutritional interventions on promoting adaptations to redox signalling</p

The effects of protein supplementation on exercise-induced inflammation and oxidative stress: a systematic review and meta-analysis

Dietary protein has been suggested to modulate inflammation and markers of oxidative stress. As such, protein supplements could be used to attenuate acute inflammation associated with trauma and exercise, or chronic inflammation associated with diseases. Exercise is known to stimulate an acute inflammatory response that resembles inflammation following trauma or injury and is therefore a useful model in which to study the effects of nutrition on inflammation. Post-exercise inflammation may also influence the regeneration process and is therefore of key interest to elite athletes. The aim of this research is to examine the effects of protein supplementation on inflammation and oxidative stress following exercise using a systematic review and meta-analysis

The Effects of Dietary Protein Supplementation on Exercise-Induced Inflammation and Oxidative Stress: A Systematic Review of Human Trials

This systematic review examined the effects of whole protein and commonly consumed amino acid supplements on markers of exercise-induced inflammation and oxidative stress and was reported according to the PRISMA guidelines. MEDLINE and SPORTDiscus were searched from inception until June 2021. The inclusion criteria were randomized clinical trials in humans, healthy adult participants (&ge;18 years), dietary protein/amino acid interventions, and measurements of oxidative stress/the redox status or inflammation post-exercise. The Cochrane Collaboration risk of bias 2 tool was used to critically appraise the studies. Data extracted from thirty-four studies were included in the systematic review (totaling 757 participants with only 10 females; age range 19&ndash;40 years). The included trials examined five types of whole protein and seven different amino acids supplements; most studies (n = 20) failed to identify statistically significant effects on markers of inflammation or oxidative stress after exercise; some (n = 14) showed either anti-inflammatory or antioxidant effects on some, but not all, markers. In conclusion, we found weak and inconsistent evidence that dietary protein/amino acid interventions can modify exercise-induced changes in oxidative stress and inflammation. However, given that these were not the primary outcomes in many of the included studies and many had design limitations, further research is warranted (Open Science Framework registration number: 10.17605/OSF.IO/AGUR2)

The effects of dietary protein supplementation on exercise-induced inflammation and oxidative stress: a systematic review of human trials

This systematic review examined the effects of whole protein and commonly consumed amino acid supplements on markers of exercise-induced inflammation and oxidative stress and was reported according to the PRISMA guidelines. MEDLINE and SPORTDiscus were searched from inception until June 2021. The inclusion criteria were randomized clinical trials in humans, healthy adult participants (≥18 years), dietary protein/amino acid interventions, and measurements of oxidative stress/the redox status or inflammation post-exercise. The Cochrane Collaboration risk of bias 2 tool was used to critically appraise the studies. Data extracted from thirty-four studies were included in the systematic review (totaling 757 participants with only 10 females; age range 19–40 years). The included trials examined five types of whole protein and seven different amino acids supplements; most studies (n = 20) failed to identify statistically significant effects on markers of inflammation or oxidative stress after exercise; some (n = 14) showed either anti-inflammatory or antioxidant effects on some, but not all, markers. In conclusion, we found weak and inconsistent evidence that dietary protein/amino acid interventions can modify exercise-induced changes in oxidative stress and inflammation. However, given that these were not the primary outcomes in many of the included studies and many had design limitations, further research is warranted (Open Science Framework registration number: 10.17605/OSF.IO/AGUR2)

Mechanically demanding eccentric exercise increases nuclear factor erythroid 2-related factor 2 activity in human peripheral blood mononuclear cells

This study examined whether eccentric exercise increases nuclear factor erythroid 2-related factor 2 (NRF2) activity in peripheral blood mononuclear cells (PBMCs). Twenty-six recreationally active males (mean [SD]; age 25 [5] y, height 178.4 [6.9] cm, body mass 77.6 [7.4] kg) were allocated to either an exercise (n = 16) or non-exercise (resting) control (n = 10) group. Eccentric exercise involved performing 100 drop jumps from a 0.6 m box. Blood was collected pre-, immediately post- and 1 h post-exercise or rest. NRF2/antioxidant response element (ARE) binding was measured in PBMCs; glutathione reductase (GR) and peroxidase (GPX) were measured in plasma. NRF2/ARE binding was greater immediately post- and 1 h post in the exercise vs. rest group (p  0.05 for all). Eccentric exercise increases NRF2/ARE binding in PBMCs compared to rest.</p

Mechanically demanding eccentric exercise increases nuclear factor erythroid 2-related factor 2 activity in human peripheral blood mononuclear cells

This study examined whether eccentric exercise increases nuclear factor erythroid 2-related factor 2 (NRF2) activity in peripheral blood mononuclear cells (PBMCs). Twenty-six recreationally active males (mean [SD]; age 25 [5] y, height 178.4 [6.9] cm, body mass 77.6 [7.4] kg) were allocated to either an exercise (n = 16) or non-exercise (resting) control (n = 10) group. Eccentric exercise involved performing 100 drop jumps from a 0.6 m box. Blood was collected pre-, immediately post- and 1 h post-exercise or rest. NRF2/antioxidant response element (ARE) binding was measured in PBMCs; glutathione reductase (GR) and peroxidase (GPX) were measured in plasma. NRF2/ARE binding was greater immediately post- and 1 h post in the exercise vs. rest group (p  0.05 for all). Eccentric exercise increases NRF2/ARE binding in PBMCs compared to rest.</p

Influence of biological sex on exercise-induced nuclear factor erythroid 2-related factor 2 and downstream targets

Objective: To evaluate whether exercise induces different nuclear factor erythroid 2-related factor 2 (NRF2) responses in males and females. Methods: 22 males and females (n=11 per group; mean [SD]: age: 25 [6] years, height: 1.71 [0.10] m, weight: 69.6 [12.3] kg) performed 100 drop jumps and 50 squat jumps. NRF2/antioxidant response element (ARE) binding in peripheral blood mononuclear cells, glutathione peroxidase (GPX) activity, and immune markers influenced by NRF2 (interleukin- 6 [IL-6], tumour necrosis factor-α [TNF-α], matrix metalloproteinase-9 [MMP-9], vascular cell adhesion molecule-1 [VCAM-1], total leukocytes, neutrophils, monocytes) were measured pre-, post-, and 1 h post-exercise. Results: NRF2/ARE binding did not significantly alter following exercise (p=0.59) and no sex differences were evident (p=0.17). Similarly, GPX activity did not change post-exercise (p=0.74) and did not differ between sexes (p=0.61). IL-6 and TNF-α did not increase post- exercise (p>0.05 for both) but were lower in females (p<0.01 for both). MMP-9 increased post-exercise (p=0.02), but no group differences were found (p=0.27). VCAM-1 was unchanged after exercise (p=0.38) and did not differ between groups (p=0.11). Total leukocytes, neutrophil, and monocytes all increased post-exercise (p<0.01 for all); neutrophils were lower (p<0.01), and monocytes higher (p=0.03) in females vs. males. Conclusion: There were no sex differences in NRF2 activity at rest and in response to an exercise bout, however, several immune markers displayed sex-specific differences, independent to NRF2. Significance: Sex differences in NRF2 signalling were not evident, suggesting males and females may incur similar redox-specific adaptations post-exercise.</p

Combined effects of green tea supplementation and eccentric exercise on nuclear factor erythroid 2-related factor 2 activity

Purpose This study investigated whether combining eccentric exercise and green tea supplementation synergistically increased nuclear factor erythroid 2-related factor 2 (NRF2) activity, a transcription factor responsible for coordinating endogenous antioxidant expression.  Methods In a double-blinded, randomized, between-subjects design, 24 males (mean [SD]; 23 [3] years, 179.6 [6.1] cm, 78.8 [10.6] kg) performed 100 drop jumps following a 6 days supplementation period with either green tea (poly)phenols (n = 12; 500 mg·d−1) or a placebo (n = 12; inulin). NRF2/antioxidant response element (ARE) binding in peripheral blood mononuclear cells (PBMCs), catalase (CAT) and glutathione reductase (GR) activity, 8-hydroxy-2′-deoxyguanosine (8-OHdG) excretion, and differential leukocyte counts were measured pre-, post-, 1 h and 24 h post-exercise.  Results Exercise did not increase NRF2/ARE binding (p = 0.12) (fold change vs rest: green tea = [post] 0.78 ± 0.45, [1 h] 1.17 ± 0.54, [24 h] 1.06 ± 0.56; placebo = [post] 1.40 ± 1.50, [1 h] 2.98 ± 3.70, [24 h] 1.04 ± 0.45). Furthermore, CAT activity (p = 0.12) and 8-OHdG excretion (p = 0.42) were unchanged in response to exercise and were not augmented by green tea supplementation (p > 0.05 for all). Exercise increased GR activity by 30% (p = 0.01), however no differences were found between supplement groups (p = 0.51). Leukocyte and neutrophil concentrations were only elevated post-exercise (p  Conclusion Eccentric exercise, either performed alone or in conjunction with green tea supplementation, did not significantly increase NRF2 activity in PBMCs.  Trial registration number osf.io/kz37g (registered: 15/09/21).</p