Frankie Tan

This study aimed to (i) describe the peak match intensities of youth football matches, (ii) quantify the variability of these peak intensities to provide references for monitoring players, and (iii) explore the association between physical capacities and peak match intensities. Match-running intensities were tracked for 32 young male footballers (age, 14.1 ± 0.8 y; height, 162.8 ± 8.3 cm; and 50.4 ± 9.6 kg) from three teams across 12 competitive matches. Peak match intensities were determined using a moving average technique, applied to total distance, high-speed distance (>14.4 km·h⁻¹), average acceleration, and PlayerLoad™. The power-law relationships were constructed to derive an intercept and slope for the match variables, and linear mixed models were used to assess the association with physical capacities and estimate the between-player, between-match, and within-player variability. No clear associations were observed between any physical capacity and the intercepts or slopes derived from match-running intensities, with wide confidence intervals overlapping trivial effects. The coefficient of variation for peak match intensities was 7.1–20.9% (between-player), 4.4–10.3% (between-match), and 6.5–21.8% (within-player). The lack of a clear association between physical capacities and peak match intensities suggests that firm conclusions cannot be drawn from these findings. The reported peak intensities and match variability may aid performance practitioners to prescribe match-specific conditioning and monitor training drills but are specific to this cohort and competitive standard.

The main research question of this review involved the identification of the various physiological and physical determinants of flat-water kayaking. A systematic search was conducted using three databases (PubMed, Google Scholar, and Microsoft Academic) between 1991 and December 2022. Quality assessment was performed using a version of the National Heart, Lung and Blood Institute checklist tailored for cross-sectional and observational studies. A total of 169 articles were identified in the initial screening. After duplicate removal and further screening for relevance, a total of 17 articles were included in the review. Altogether, it was found that flat-water kayaking performance was strongly correlated with maximum oxygen uptake (VO_2max), aerobic and anaerobic thresholds, peak aerobic and anaerobic capacity measure in lab and on the water, and upper and lower-body strength and power, which were measured using heavy resistance, as well as isometric and isokinetic implements. What is less clear is the association between total lean mass and flat-water kayaking performance. However, this may largely be due to the differences in when the measurements were taken.

Background: The aim of this study was to evaluate the efficacy of a six-week dispersed Wingate Anaerobic test (WAnT) cycle exercise training protocol on peak aerobic power (VO_2peak), isokinetic leg strength, insulin sensitivity, lipid profile and quality of life, in healthy adults. Methods: We conducted a match-controlled cohort trial and participants were assigned to either the training (intervention, INT, N = 16) or non-training (control, CON, N = 17) group. INT performed 30-s WAnT bouts three times a day in the morning, afternoon and evening with each bout separated by ~4 h of rest, performed for 3 days a week for 6 weeks. Criterion measures of peak oxygen uptake (VO_2peak), leg strength, insulin markers such as homeostatic model assessment (HOMA) and quantitative insulin-sensitivity check index (QUICKI), blood lipids profile and health-related quality of life (HRQL) survey were assessed before and after 6 weeks in both groups. Results: Absolute VO_2peak increased by 8.3 ± 7.0% (p < 0.001) after INT vs. 0.9 ± 6.1% in CON (p = 0.41) group. Maximal voluntary contraction at 30°·s⁻¹ of the dominant lower-limb flexors in INT increased significantly post-training (p = 0.03). There were no changes in the INT individuals’ other cardiorespiratory markers, HOMA, QUICKI, blood lipids, and HRQL measures (all p > 0.05) between pre- and post-training; but importantly, no differences were observed between INT and CON groups (all p > 0.05). Conclusions: The results indicate that 6 weeks of dispersed sprint cycle training increased cardiorespiratory fitness and dynamic leg strength but had minimal impact on insulin sensitivity, blood lipids and quality of life in the exercising individuals.

Background: Intense exercise is a systemic stressor associated with the release of “danger” molecules – alarmins, by damaged or dying cells into systemic circulation to evoke a sterile inflammatory response. Compared with research in clinical diseases, physiological responses of alarmins to exercise and training are not well studied. Short-term responses to exercise and training using a panel of alarmins – HMGB1, S100A8/A9, HSP70 and sRAGE may reveal unique aspects of stress responses to strenuous exercise, with important ramifications when prescribing exercise to generally healthy adults. Methods: A 3-week, high-intensity training program was performed by healthy young men (N = 7). Concurrent aerobic and resistance exercises were performed on 3 consecutive days each week. Blood and saliva were collected before (Pre), immediately after (Post), and 30 min (30 min) after exercise each week, and 24 h after the final exercise session in week 3 (24 h). Results: Plasma HMGB1, S100A8/A9 and HSP70 increased from Pre to Post (P < 0.05), although at different timepoints during the study, and displayed different kinetics from IL-10, IL-8 and IFN-γ, suggesting unique mechanisms involved in modulating their release and clearance. CD14⁺CD16⁻ monocytes increased from Pre to Post across 3 weeks; CD14⁺CD16⁺ monocytes increased from Pre to Post in week 2 and 3 (P < 0.05). ΔHMGB1 and ΔHSP70 correlated positively with ΔMCP-1 during 3 weeks of training. As well, ΔHMGB1 correlated positively with CD14⁺CD16⁻ monocytes, suggesting higher alarmin release after strenuous exercise may involve increase in circulating monocytes. Conclusions: Perturbations in systemic alarmins are novel biological signatures for assessing the inflammatory milieu of healthy adults during high-intensity exercise.

Fibroblast growth factor 21 (FGF21) and adiponectin increase the expression of genes involved in antioxidant pathways, but their roles in mediating oxidative stress and arterial stiffness with ageing and habitual exercise remain unknown. We explored the role of the FGF21–adiponectin axis in mediating oxidative stress and arterial stiffness with ageing and habitual exercise. Eighty age- and sex-matched healthy individuals were assigned to younger sedentary or active (18–36 years old, n = 20 each) and older sedentary or active (45–80 years old, n = 20 each) groups. Arterial stiffness was measured indirectly using pulse wave velocity (PWV). Fasted plasma concentrations of FGF21, adiponectin and oxidized low-density lipoprotein (oxLDL) were measured. PWV was 0.2-fold higher and oxLDL concentration was 25.6% higher (both p < 0.001) in older than younger adults, despite no difference in FGF21 concentration (p = 0.097) between age groups. PWV (p = 0.09) and oxLDL concentration (p = 0.275) did not differ between activity groups but FGF21 concentration was 9% lower in active than sedentary individuals (p = 0.011). Adiponectin concentration did not differ by age (p = 0.642) or exercise habits (p = 0.821). In conclusion, age, but not habitual exercise, was associated with higher oxidative stress and arterial stiffness. FGF21 and adiponectin did not differ between younger and older adults, meaning that it is unlikely that they mediate oxidative stress and arterial stiffness in healthy adults.

Background: Intense exercise is a systemic stressor associated with the release of “danger” molecules – alarmins, by damaged or dying cells into systemic circulation to evoke a sterile inflammatory response. Compared with research in clinical diseases, physiological responses of alarmins to exercise and training are not well studied. Short-term responses to exercise and training using a panel of alarmins – HMGB1, S100A8/A9, HSP70 and sRAGE may reveal unique aspects of stress responses to strenuous exercise with important ramifications when prescribing exercise to generally healthy adults. Methods: A 3-week, high-intensity training program was performed by healthy young men (N = 7). Concurrent aerobic and resistance exercises were performed on 3 consecutive days each week. Blood and saliva were collected before (Pre), immediately after (Post), and 30 min (30 min) after exercise each week, and 24 h after the final exercise session in week 3 (24 h). Results: Plasma HMGB1, S100A8/A9 and HSP70 increased from Pre to Post (P < 0.05), although at different timepoints during the study, and displayed different kinetics from IL-10, IL-8 and IFN-γ, suggesting unique mechanisms involved in modulating their release and clearance. CD14⁺CD16^- monocytes increased from Pre to Post across 3 weeks; CD14⁺CD16⁺ monocytes increased from Pre to Post in week 2 and 3 (P < 0.05). ΔHMGB1 and ΔHSP70 correlated positively with ΔMCP-1 during 3 weeks of training, while ΔHMGB1 correlated positively with CD14⁺CD16^- monocytes, suggesting higher alarmin release after strenuous exercise may involve increase in circulating monocytes. Conclusions: Perturbations in systemic alarmins are novel biological signatures for assessing the inflammatory milieu of healthy adults during high-intensity exercise.

Introduction Aging increases the prevalence of glucose intolerance, but exercise improves glucose homeostasis. The fibroblast growth factor 21 (FGF21)–adiponectin axis helps regulate glucose metabolism. However, the role of FGF21 in mediating glucose metabolism with aging and exercise remains unknown. Purpose This study examined whether FGF21 responses to a glucose challenge are associated with habitual exercise, aging and glucose regulation. Methods Eighty age- and sex-matched healthy individuals were assigned to young sedentary and active (≤36 yr, n = 20 each group) and older sedentary and active (≥45 yr, n = 20 each group) groups. Fasted and postprandial blood glucose concentration and plasma concentration of insulin, FGF21, and adiponectin were determined during an oral glucose tolerance test (OGTT). Results During the OGTT, glucose concentrations were 9% higher (P = 0.008) and FGF21 concentrations were 58% higher (P = 0.014) in the older than the younger group, independent of activity status. Active participants had 40% lower insulin concentration and 53% lower FGF21 concentration than sedentary participants, independent of age (all P < 0.001). Adiponectin concentration during the OGTT did not differ by age (P = 0.448) or activity status (P = 0.611). Within the younger group, postprandial glucose, insulin and FGF21 concentrations during the OGTT were lower in active than in sedentary participants. In the older group, only postprandial insulin and FGF21 concentrations were lower in active participants. Conclusions FGF21, but not adiponectin, response during the OGTT is higher in older than younger adults and lower in active than sedentary individuals. Exercise-associated reduction in OGTT glucose concentrations was observed in younger but not older adults.