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Mikkel Oxfeldt, Line B. Dalgaard, Astrid A. Jørgensen and Mette Hansen

Objective: To identify the prevalence of hormonal contraceptive (HC) use, menstrual cycle disturbances, and self-perceived physical and emotional symptoms related to the menstrual cycle/pill cycle in elite female athletes. Methods: One hundred eighty-six Danish elite female athletes completed an online questionnaire to assess menstrual status and history, use of HCs, and self-perceived physical and emotional symptoms related to the menstrual cycle or HC use. Results: Fifty-seven percent of elite female athletes in Denmark use HC, with 74% using combined HCs and 26% using progestin only. Sixty percent of oral contraceptive users reported having manipulated their menstrual cycle by continuous oral contraceptive use. Forty-nine percent of non-HC users had a regular menstrual cycle, while 51% experienced menstrual disturbances, with 1 athlete being primary amenorrheic and 13 athletes having secondary amenorrhea. Menstrual disturbances were experienced by a larger proportion of endurance athletes (69%) compared with athletes performing power and technical disciplines. In endurance athletes amenorrhea was associated with a higher cardiovascular training volume (P < .001). Negative symptoms related to the menstrual/pill cycle were reported by both HC and non-HC users, whereas positive physical symptoms were experienced more often among the non-HC (14%) versus HC users (2%) (P < .01). Notably, 13% of the athletes reported that negative symptoms sometimes/always caused them to not participate in or complete the scheduled training. Conclusion: HC use is common among elite athletes, and continuation of HC is used to manipulate the menstrual cycle in relation to sport competitions. HC use does not abolish dysmenorrhea, but it may reduce emotional-related side effects. Menstrual disturbances are frequent in endurance athletes and are associated with cardiovascular training volume.

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Nina Rica Wium Geiker, Mette Hansen, Jette Jakobsen, Michael Kristensen, Rikke Larsen, Niklas R. Jørgensen, Birthe S. Hansen and Susanne Bügel

Impaired muscle function has been coupled to vitamin D insufficiency in young women and in elderly men and women. Those living at Northern latitudes are at risk for vitamin D insufficiency due to low sun exposure which may be more pronounced among elite swimmers because of their indoor training schedules. We aimed to examine vitamin D status among young elite swimmers and evaluate the association between vitamin D status and muscle strength. Twenty-nine swimmers, 12 female and 17 male (16–24 years) residing at latitude 55–56°N were studied in March and April. Blood samples were analyzed for serum 25-hydroxyvitamin D (s-25(OH)D) and hand-grip strength was measured as marker of muscle strength. Subjects´ vitamin D and calcium intake were assessed by food frequency questionnaire and sun exposure and training status by questionnaires. Mean (± SD) s-25(OH)D was 52.6 ± 18.3nmol/L among all swimmers. In 45% of the swimmers s-25(OH)D was below 50 nmol/L. Female swimmers had higher s-25(OH)D concentration than male swimmers (61.7 ± 17,5 nmol/L vs. 46.2 ± 16,5 nmol/L, p = .026). Among male swimmers, those with sufficient vitamin D status had higher hand grip strength than those with insufficient vitamin D status (50.6 ± 6.4 kg vs. 41.1 ± 7.8 kg, p = .02). Among Danish elite swimmers 45% had an insufficient vitamin D status during the spring; the prevalence being higher among male swimmers. Muscle strength was significantly higher in male swimmers with sufficient vitamin D status.

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Mads S. Larsen, Dagmar Clausen, Astrid Ank Jørgensen, Ulla R. Mikkelsen and Mette Hansen

Recent studies demonstrate that protein ingestion immediately before sleep improves muscle recovery during the night following resistance exercise. Whether this feeding strategy benefits recovery from endurance training has yet to be established. The aim of this study was to investigate the effects of whey protein isolate ingested every night before sleep on subsequent performance and circulatory markers of muscular recovery during a week of intensified endurance training mimicking a training camp. In a parallel design, 32 trained runners underwent a 1-week intervention with a rigorously controlled diet (carbohydrate = 7.2 g·kg−1·day−1, protein = 1.8 g·kg−1·day−1, and fat = 1.0 g·kg−1·day−1) and exercise program (11 sessions) while receiving either a protein (0.5 g·kg−1·day−1) or carbohydrate (0.5 g·kg−1·day−1) beverage every night before sleep. Blood samples were obtained on the morning of Days 1, 4, 7, and 8 and analyzed for markers of muscle damage (creatine kinase, lactate dehydrogenase, and myoglobin). The postintervention 5-km time-trial performance was significantly impaired in both groups (11 ± 24 s, p < .01). Plasma creatine kinase (227% ± 221%, p < .01), lactate dehydrogenase (18% ± 22%, p < .01), and myoglobin (72% ± 62%, p < .01) increased gradually throughout the week with no difference between the groups (p > .05). In conclusion, the presleep protein ingestion did not reduce the decline in performance or ameliorate the rise of circulatory markers of muscle damage during a week of intensified training when compared with the isocaloric carbohydrate ingestion.

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Mette Hansen, Jens Bangsbo, Jørgen Jensen, Bo Martin Bibby and Klavs Madsen

This trial aimed to examine the effect of whey protein hydrolysate intake before and after exercise sessions on endurance performance and recovery in elite orienteers during a training camp. Eighteen elite orienteers participated in a randomized controlled intervention trial during a 1-week training camp (13 exercise sessions). Half of the runners (PRO-CHO) ingested a protein drink before (0.3 g kg−1) and a protein-carbohydrate drink after (0.3 g protein kg−1 and 1 g carbohydrate kg−1) each exercise session. The others ingested energy and timematched carbohydrate drinks (CHO). A 4-km run-test with 20 control points was performed before and on the last day of the intervention. Blood and saliva were obtained in the mornings, before and after run-tests, and after the last training session. During the intervention, questionnaires were fulfilled regarding psychological sense of performance capacity and motivation. PRO-CHO and not CHO improved performance in the 4-km run-test (interaction p < .05). An increase in serum creatine kinase was observed during the week, which was greater in CHO than PRO-CHO (interactionp < .01). Lactate dehydrogenase (p < .001) and cortisol (p = .057) increased during the week, but the change did not differ between groups. Reduction in sense of performance capacity during the intervention was greater in CHO (p < .05) than PRO-CHO. In conclusion, ingestion of whey protein hydrolysate before and after each exercise session improves performance and reduces markers of muscle damage during a strenuous 1-week training camp. The results indicate that protein supplementation in conjunction with each exercise session facilitates the recovery from strenuous training in elite orienteers.