Marc Sim

Iron status and the acute post-exercise hepcidin response in athletes

This study explored the relationship between serum ferritin and hepcidin in athletes. Baseline serum ferritin levels of 54 athletes from the control trial of five investigations conducted in our laboratory were considered; athletes were grouped according to values <30 μg/L (SF<30), 30–50 μg/L (SF30–50), 50–100 μg/L (SF50–100), or >100 μg/L (SF>100). Data pooling resulted in each athlete completing one of five running sessions: (1) 8×3 min at 85% vVO2peak; (2) 5×4 min at 90% vVO2peak; (3) 90 min continuous at 75% vVO2peak; (4) 40 min continuous at 75% vVO2peak; (5) 40 min continuous at 65% vVO2peak. Athletes from each running session were represented amongst all four groups; hence, the mean exercise duration and intensity were not different (p>0.05). Venous blood samples were collected pre-, post- and 3 h post-exercise, and were analysed for serum ferritin, iron, interleukin-6 (IL-6) and hepcidin-25. Baseline and post-exercise serum ferritin levels were different between groups (p<0.05). There were no group differences for pre- or post-exercise serum iron or IL-6 (p>0.05). Post-exercise IL-6 was significantly elevated compared to baseline within each group (p<0.05). Pre- and 3 h post-exercise hepcidin-25 was sequentially greater as the groups baseline serum ferritin levels increased (p<0.05). However, post-exercise hepcidin levels were only significantly elevated in three groups (SF30–50, SF50–100, and SF>100; p<0.05). An athletes iron stores may dictate the baseline hepcidin levels and the magnitude of post-exercise hepcidin response. Low iron stores suppressed post-exercise hepcidin, seemingly overriding any inflammatory-driven increases.

Iron Regulation in Athletes: Exploring the Menstrual Cycle and Effects of Different Exercise Modalities on Hepcidin Production

The trace element iron plays a number of crucial physiological roles within the body. Despite its importance, iron deficiency remains a common problem among athletes. As an individuals iron stores become depleted, it can affect their well-being and athletic capacity. Recently, altered iron metabolism in athletes has been attributed to postexercise increases in the iron regulatory hormone hepcidin, which has been reported to be upregulated by exercise-induced increases in the inflammatory cytokine interleukin-6. As such, when hepcidin levels are elevated, iron absorption and recycling may be compromised. To date, however, most studies have explored the acute postexercise hepcidin response, with limited research seeking to minimize/attenuate these increases. This review summarizes the current knowledge regarding the postexercise hepcidin response under a variety of exercise scenarios and highlights potential areas for future research-such as: a) the use of hormones though the female oral contraceptive pill to manipulate the postexercise hepcidin response, b) comparing the use of different exercise modes (e.g., cycling vs. running) on hepcidin regulation.

RECOVERY EFFECTS OF HYPEROXIC GAS INHALATION OR CONTRAST WATER IMMERSION ON THE POSTEXERCISE CYTOKINE RESPONSE, PERCEPTUAL RECOVERY, AND NEXT DAY EXERCISE PERFORMANCE

Abstract Peeling, P, Fulton, S, Sim, M, and White, J. Recovery effects of hyperoxic gas inhalationor contrast water immersion on the postexercise cytokine response, perceptual recovery, and next day exercise performance. J Strength Cond Res 26(4): 968–975, 2012—The effect of different recovery modalities on the postexercise cytokine response, perceptual recovery, and subsequent day athletic performance were investigated. Eight highly trained athletes completed 3 swimming sessions consisting of 20 × 200 m efforts, in a counterbalanced repeated-measures design. At the conclusion of each session, athletes undertook a 30-minute recovery intervention of contrast water therapy (CWT), supplemental oxygen (HYP), or passive rest (CON). Venous blood samples were analyzed for levels of interleukin-6 (IL-6) at the pre-, post-, and 30-minute postswim time points, and a rating of perceived recovery was recorded at the conclusion of the 30-minute intervention and upon returning to the pool 12 hour later. Finally, a 200-m swim time trial was completed as a measure of next day performance. The results showed that there was a significant increase in IL-6 at the completion of exercise, which persisted after 30 minutes of recovery (p < 0.05), with no differences evident between the groups. Additionally, the perception of recovery after the 30-minute intervention was significantly lower in the CON when compared with the CWI and HYP (p < 0.05). However, there were no differences in the 12-hour postrecovery time trial performances. These results suggest that a 30-minute recovery intervention using CWT or HYP has limited influence on the acute-phase response or on improving subsequent day athletic performance. However, strength and conditioning specialists should encourage the use of a structured postexercise recovery procedure because the evidence suggests that the acute perception of recovery is much greater when some form of intervention is implemented in comparison with no recovery procedure at all.

Cardiovascular health benefits of specific vegetable types: A narrative review

Adequate vegetable consumption is one of the cornerstones of a healthy diet. The recommendation to increase vegetable intake is part of most dietary guidelines. Despite widespread and long-running public health messages to increase vegetable intake, similar to other countries worldwide, less than 1 in 10 adult Australians manage to meet target advice. Dietary guidelines are predominantly based on studies linking diets high in vegetables with lower risk of chronic diseases. Identifying vegetables with the strongest health benefits and incorporating these into dietary recommendations may enhance public health initiatives around vegetable intake. These enhanced public health initiatives would be targeted at reducing the risk of chronic diseases, such as cardiovascular diseases (CVD). Specific vegetable types contain high levels of particular nutrients and phytochemicals linked with cardiovascular health benefits. However, it is not clear if increasing intake of these specific vegetable types will result in larger benefits on risk of chronic diseases. This review presents an overview of the evidence for the relationships of specific types of vegetables, including leafy green, cruciferous, allium, yellow-orange-red and legumes, with subclinical and clinical CVD outcomes in observational epidemiological studies.

Interleukin-6 and Hepcidin Levels during Hormone-Deplete and Hormone-Replete Phases of an Oral Contraceptive Cycle: A Pilot Study

Background: In the past, elevated estradiol levels were reported to downregulate the iron regulatory hormone hepcidin, thereby potentially improving iron metabolism. As estrogen plays a role in regulating the menstrual cycle and can influence the cytokine interleukin-6 (IL-6; a hepcidin up-regulator), this investigation examined the effects of estradiol supplementation achieved by the use of a monophasic oral contraceptive pill (OCP) on IL-6, hepcidin levels and iron status during the hormone-deplete versus hormone-replete phases within an oral contraceptive cycle (OCC). Methods: Fifteen healthy female OCP users were recruited and provided a venous blood sample on 2 separate mornings during a 28-day period. These included (a) days 2-4 of the OCC, representing a hormone-free withdrawal period (WD); (b) days 12-14 of the OCC, representing the end of the first week of active hormone therapy (AHT). Results: IL-6 and hepcidin levels were not significantly different at WD and AHT. Serum ferritin was significantly higher (p = 0.039) during AHT as compared to WD. Conclusions: Fluctuations in OCP hormones (estradiol and/or progestogen) had no effect on basal IL-6 and hepcidin levels in young women. Nevertheless, elevated ferritin levels recorded during AHT may indicate that OCP hormones can positively influence iron stores within an OCC despite unchanged hepcidin levels.Background: Diarrhoea is a major cause of morbidity and mortality in children. Most deaths are caused by dehydration and are easily preventable by using oral rehydration therapy. Early management and recognition of danger signs are key strategies in treating diarrhoeal diseases at home. Aims & Objectives: 1. To assess the knowledge of caregivers regarding childhood diarrhoea and signs of dehydration and danger signs 2. To assesses the mothers’ approach towards its home based management and health seeking behaviour. Material & Methods: A community based cross sectional study was conducted in different rural blocks of Lucknow selected by multistage sampling. Total of 240 households were interviewed to achieve targeted sample size of 410 children of less than five years age group. Perception of diarrhoea signs of dehydration and danger signs were asked to caregivers and associations were established maternal knowledge and presence or absence of diarrhoea in children of less than five age group. Results: The study showed that 74.2 per cent of caregivers recognized diarrhoea correctly i.e. increased frequency of watery stool or blood and mucus in stool or both. Decreased urination or dis-coloured urine (89.6%) thirsty or eagerly drinking (55.7%) dry mouth and tongue (37.7%) etc. were recognized by caregivers as major signs of dehydration*. Caregivers recognized child getting seeker / unconscious (94.9%) not able to drink or breast feed (66.7%) blood in stool (59%) etc. as danger signs* developing during diarrhoea episodes of child. Conclusions: Caregiver’s knowledge regarding recognition of childhood diarrhoea in proper and early detection of signs of dehydration and development of danger signs at community level are keys to prevention of diarrhoea related death in less than five years age group.

Vegetable Diversity, Injurious Falls, and Fracture Risk in Older Women: A Prospective Cohort Study

The importance of vegetable diversity for the risk of falling and fractures is unclear. Our objective was to examine the relationship between vegetable diversity with injurious falling and fractures leading to hospitalization in a prospective cohort of older Australian women (n = 1429, ≥70 years). Vegetable diversity was quantified by assessing the number of different vegetables consumed daily. Vegetable intake (75 g servings/day) was estimated using a validated food frequency questionnaire at baseline (1998). Over 14.5 years, injurious falls (events = 568, 39.7%), and fractures (events = 404, 28.3%) were captured using linked health records. In multivariable-adjusted Cox regression models, women with greater vegetable diversity (per increase in one different vegetable/day) had lower relative hazards for falls (8%; p = 0.02) and fractures (9%; p = 0.03). A significant interaction between daily vegetable diversity (number/day) and total vegetable intake (75 g servings/day) was observed for falls (pinteraction = 0.03) and fractures (pinteraction < 0.001). The largest benefit of higher vegetable diversity were observed in the one third of women with the lowest vegetable intake (<2.2 servings/day; falls HR 0.83 95% CI (0.71–0.98); fractures HR 0.74 95% CI (0.62–0.89)). Increasing vegetable diversity especially in older women with low vegetable intake may be an effective way to reduce injurious fall and fracture risk.

A comparison of displacement and energetic variables between three team sport GPS devices

ABSTRACT This study compared the outputs of three different commercially-available GPS player-tracking devices for a range of commonly used displacement and energetic variables in activities replicating team sport movements. Professional male soccer players (n = 7), simultaneously wore three GPS devices (Catapult OptimEye S5, GPExe Pro 1, StatSport ViperPod) whilst completing four separate drills, comprising progressively more complex changes in speed and direction. Displacement (distance, speed) and energetic (energy cost, metabolic power, energy expenditure) variables were compared for each device. All three devices tended to under-estimate distance compared to the known value for each drill, with only minor and inconsistent differences between devices. There were no differences between devices for average speed. For energetic variables, substantial differences were found between each device, and these differences magnified as movement tasks became more erratic. Given that energetic variables are derived from measures of instantaneous speed, and also incorporate the magnitude and direction of change between successive data points, these differences may be attributable to disparities in raw data quality, filtering techniques and calculation methods. In order to provide comparable estimates of energetic variables in team sports, player-tracking devices must be capable of accurately recording instantaneous velocity in activities comprising frequent changes in speed and direction.

Sand training: Exercise-induced muscle damage and inflammatory responses to matched-intensity exercise

Abstract This study compared markers of muscle damage and inflammation elevated by a matched-intensity interval running session on soft sand and grass surfaces. In a counterbalanced, repeated-measures and crossover design, 10 well-trained female athletes completed 2 interval-based running sessions 1 week apart on either a grass or a sand surface. Exercise heart rate (HR) was fixed at 83–88% of HR maximum. Venous blood samples were collected pre-, post- and 24 h post-exercise, and analysed for myoglobin (Mb) and C-reactive protein (CRP). Perceptual ratings of exertion (RPE) and muscle soreness (DOMS) were recorded immediately post- and 24 h post-exercise. A significant time effect showed that Mb increased from pre- to post-exercise on grass (p = .008) but not on sand (p = .611). Furthermore, there was a greater relative increase in Mb on grass compared with that on sand (p = .026). No differences in CRP were reported between surfaces (p > .05). The HR, RPE and DOMS scores were not significantly different between conditions (p  >  .05). These results suggest that in response to a matched-intensity exercise bout, markers of post-exercise muscle damage may be reduced by running on softer ground surfaces. Such training strategy may be used to minimize musculoskeletal strain while still incurring an equivalent cardiovascular training stimulus.