- Sim, Marc, Dawson, Brian, Landers, Grant, Swinkels, Dorine, Wiegerinck, Erwin, Yeap, Bu Beng, Trinder, Debbie, Peeling, Peter
- Authors: Sim, Marc , Dawson, Brian , Landers, Grant , Swinkels, Dorine , Wiegerinck, Erwin , Yeap, Bu Beng , Trinder, Debbie , Peeling, Peter
- Date: 2017
- Type: Text , Journal article
- Relation: Annals of Nutrition and Metabolism Vol. 70, no. 2 (2017), p. 100-105
- Full Text: false
- Reviewed:
- Description: 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. © 2017 S. Karger AG, Basel.
A seven day running training period increases basal urinary hepcidin levels as compared to cycling
- Sim, Marc, Dawson, Brian, Landers, Grant, Swinkels, Dorine, Tjalsma, Harold, Wiegerinck, Erwin, Trinder, Debbie, Peeling, Peter
- Authors: Sim, Marc , Dawson, Brian , Landers, Grant , Swinkels, Dorine , Tjalsma, Harold , Wiegerinck, Erwin , Trinder, Debbie , Peeling, Peter
- Date: 2014
- Type: Text , Journal article
- Relation: Journal of the International Society of Sports Nutrition Vol. 11, no. 1 (2014), p. 1-9
- Full Text:
- Reviewed:
- Description: BACKGROUND: This investigation compared the effects of an extended period of weight-bearing (running) vs. non-weight-bearing (cycling) exercise on hepcidin production and its implications for iron status. METHODS: Ten active males performed two separate exercise training blocks with either running (RTB) or cycling (CTB) as the exercise mode. Each block consisted of five training sessions (Day 1, 2, 4, 5, 6) performed over a seven day period that were matched for exercise intensity. Basal venous blood samples were obtained on Day 1 (D1), and on Recovery Days 3 (R3) and 7 (R7) to assess iron status, while basal and 3 h post-exercise urinary hepcidin levels were measured on D1, D2, D6, as well as R3 and R7 (basal levels only) for each condition. RESULTS: Basal urinary hepcidin levels were significantly elevated (p = 0.05) at D2, R3 and R7 as compared to D1 in RTB. Furthermore, 3 h post-exercise urinary hepcidin levels on D1 were also significantly higher in RTB compared to CTB (p = 0.05). In CTB, urinary hepcidin levels were not statistically different on D1 as compared to R7. Iron parameters were not significantly different at D1 compared to R3 and R7 during both conditions. CONCLUSIONS: These results suggest that basal hepcidin levels may increase over the course of an extended training program, especially if a weight-bearing exercise modality is undertaken. However, despite any variations in hepcidin production, serum iron parameters in both RTB and CTB were unaffected, possibly due to the short duration of each training block. In comparing running to cycling, non-weight-bearing activity may require more training sessions, or sessions of extended duration, before any significant changes in basal hepcidin levels appear. Chronic elevations in hepcidin levels may help to explain the high incidence of iron deficiency in athletes.
- Authors: Sim, Marc , Dawson, Brian , Landers, Grant , Swinkels, Dorine , Tjalsma, Harold , Wiegerinck, Erwin , Trinder, Debbie , Peeling, Peter
- Date: 2014
- Type: Text , Journal article
- Relation: Journal of the International Society of Sports Nutrition Vol. 11, no. 1 (2014), p. 1-9
- Full Text:
- Reviewed:
- Description: BACKGROUND: This investigation compared the effects of an extended period of weight-bearing (running) vs. non-weight-bearing (cycling) exercise on hepcidin production and its implications for iron status. METHODS: Ten active males performed two separate exercise training blocks with either running (RTB) or cycling (CTB) as the exercise mode. Each block consisted of five training sessions (Day 1, 2, 4, 5, 6) performed over a seven day period that were matched for exercise intensity. Basal venous blood samples were obtained on Day 1 (D1), and on Recovery Days 3 (R3) and 7 (R7) to assess iron status, while basal and 3 h post-exercise urinary hepcidin levels were measured on D1, D2, D6, as well as R3 and R7 (basal levels only) for each condition. RESULTS: Basal urinary hepcidin levels were significantly elevated (p = 0.05) at D2, R3 and R7 as compared to D1 in RTB. Furthermore, 3 h post-exercise urinary hepcidin levels on D1 were also significantly higher in RTB compared to CTB (p = 0.05). In CTB, urinary hepcidin levels were not statistically different on D1 as compared to R7. Iron parameters were not significantly different at D1 compared to R3 and R7 during both conditions. CONCLUSIONS: These results suggest that basal hepcidin levels may increase over the course of an extended training program, especially if a weight-bearing exercise modality is undertaken. However, despite any variations in hepcidin production, serum iron parameters in both RTB and CTB were unaffected, possibly due to the short duration of each training block. In comparing running to cycling, non-weight-bearing activity may require more training sessions, or sessions of extended duration, before any significant changes in basal hepcidin levels appear. Chronic elevations in hepcidin levels may help to explain the high incidence of iron deficiency in athletes.
Effect of tart cherry juice on recovery and next day performance in well-trained Water Polo players
- McCormick, Rachel, Peeling, Peter, Binnie, Martyn, Dawson, Brian, Sim, Marc
- Authors: McCormick, Rachel , Peeling, Peter , Binnie, Martyn , Dawson, Brian , Sim, Marc
- Date: 2016
- Type: Text , Journal article
- Relation: Journal of the International Society of Sports Nutrition Vol. 13, no. 1 (2016), p. 1-8
- Full Text:
- Reviewed:
- Description: Background: Tart Montmorency cherries contain high concentrations of phytochemicals and anthocyanins, which have recently been linked to improved athletic recovery and subsequent performance. To date however, previous work reporting promising results has focused on land-based endurance sports, with any potential benefits to team sports remaining unknown. As such, this investigation set-out to examine the effect of supplemental tart cherry juice (CJ) on recovery and next day athletic performance in highly-trained water-based team sport athletes over seven days. Methods: In a randomised, double-blind, repeated measures, crossover design, nine male Water Polo athletes were supplemented with CJ or a placebo equivalent (PLA) for six consecutive days. Prior to, and at the completion of the supplementation period, water-based performance testing was conducted. On day 6, participants also undertook a fatiguing simulated team game activity. Venous blood samples were collected (Pre-exercise: day 1, 6 and 7; Post-exercise: day 6) to investigate markers of inflammation [Interleukin-6 (IL-6); C-reactive protein (CRP)] and oxidative stress [Uric Acid (UA); F2-Isoprostane (F2-IsoP)]. A daily diary was also completed (total quality of recovery, delayed onset muscle soreness) as a measure of perceptual recovery. Results: In both conditions, day 6 post-exercise IL-6 was significantly higher than pre-exercise and day 7 (p<0.05); CRP was greater on day 7 as compared to day 6 pre- and post-exercise (p<0.05); F2-IsoP was significantly lower on day 7 as compared to day 1 and day 6 (p<0.05); UA remained unchanged (p>0.05). No differences were found for any performance or recovery measures. Conclusions: The lack of difference observed in the blood markers between groups may reflect the intermittent, non-weight bearing demands of Water Polo, with such activity possibly unable to create a substantial inflammatory response or oxidative stress (over 7 days) to impede performance; thereby negating any potential beneficial effects associated with CJ supplementation. Trial registration: This trial was registered with the Australian and New Zealand Clinical Trials Registry (ANZCTR). Registration number: ACTRN12616001080415. Date registered: 11/08/2016, retrospectively registered. © 2016 The Author(s).
- Authors: McCormick, Rachel , Peeling, Peter , Binnie, Martyn , Dawson, Brian , Sim, Marc
- Date: 2016
- Type: Text , Journal article
- Relation: Journal of the International Society of Sports Nutrition Vol. 13, no. 1 (2016), p. 1-8
- Full Text:
- Reviewed:
- Description: Background: Tart Montmorency cherries contain high concentrations of phytochemicals and anthocyanins, which have recently been linked to improved athletic recovery and subsequent performance. To date however, previous work reporting promising results has focused on land-based endurance sports, with any potential benefits to team sports remaining unknown. As such, this investigation set-out to examine the effect of supplemental tart cherry juice (CJ) on recovery and next day athletic performance in highly-trained water-based team sport athletes over seven days. Methods: In a randomised, double-blind, repeated measures, crossover design, nine male Water Polo athletes were supplemented with CJ or a placebo equivalent (PLA) for six consecutive days. Prior to, and at the completion of the supplementation period, water-based performance testing was conducted. On day 6, participants also undertook a fatiguing simulated team game activity. Venous blood samples were collected (Pre-exercise: day 1, 6 and 7; Post-exercise: day 6) to investigate markers of inflammation [Interleukin-6 (IL-6); C-reactive protein (CRP)] and oxidative stress [Uric Acid (UA); F2-Isoprostane (F2-IsoP)]. A daily diary was also completed (total quality of recovery, delayed onset muscle soreness) as a measure of perceptual recovery. Results: In both conditions, day 6 post-exercise IL-6 was significantly higher than pre-exercise and day 7 (p<0.05); CRP was greater on day 7 as compared to day 6 pre- and post-exercise (p<0.05); F2-IsoP was significantly lower on day 7 as compared to day 1 and day 6 (p<0.05); UA remained unchanged (p>0.05). No differences were found for any performance or recovery measures. Conclusions: The lack of difference observed in the blood markers between groups may reflect the intermittent, non-weight bearing demands of Water Polo, with such activity possibly unable to create a substantial inflammatory response or oxidative stress (over 7 days) to impede performance; thereby negating any potential beneficial effects associated with CJ supplementation. Trial registration: This trial was registered with the Australian and New Zealand Clinical Trials Registry (ANZCTR). Registration number: ACTRN12616001080415. Date registered: 11/08/2016, retrospectively registered. © 2016 The Author(s).
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