LEADING ARTICLE

Sports Medicine 12 (3): 152-160, 1991 0112-1642/91 /0009-0152/$04.50/0 © Adis International Limited. All rights reserved. SP0145A

Sports Injuries and Oral Contraceptive Use Is There a Relationship? Jesper Moller Nielsen and Mats Hammar Department of Obstetrics and Gynaecology, County Hospital of Varnamo, and University Hospital of Link6ping, Link6ping, Sweden

The participation of women in sporting activities at various levels is increasing, even in the traditionally male activities such as soccer and marathon running. The amount and intensity of training and competition are increasing and so, thereby, is the risk for injuries. In contrast to men, women go through a regular endocrine cycle once every month. Some studies suggest that physical performance varies during the menstrual cycle, usually being decreased before menstruation. Furthermore, there are indications that the risk of being

involved in accidents and injuries in general is increased during the premenopausal period. The phenomenon may also increase the risk of sports injuries. Many fertile women use oral contraceptives (OCs) to prevent unwanted pregnancy and also to regulate irregular cycles and to decrease dysmenorrhoea. The steroids contained in OCs significantly affect the hormonal cycle, mainly through suppression of the pituitary. Since hormonal fluctuations during the menstrual cycle may influence the risk of injury during sporting activities, the question may be raised as to whether OCs may affect physical performance and the risk for sports injuries, by means of their effects on the hormonal cycle. Furthermore, OCs may influence other variables important for physical performance, such as joint laxity and neuromuscular coordination. The purpose of this paper is to discuss the possible relationship between the use of OCs and the risk of sports injuries.

To understand these questions, it is important to have some insight into the regulation of the menstrual cycle and the mechanisms of action of OCs. This will thus be briefly summarised before dealing with the question of a possible relationship between sports injuries and use of OCs.

1. Background 1.1 Regulation of the Menstrual Cycle The basis of the menstrual cycle is the endocrinic coordination between the hypothalamus, the pituitary and the ovarian follicles (Speroff et al. 1983). Pulsatile release of the hypothalamic hormone GnRH (gonadotrophin-releasing hormone; LH-RH) induces the production and release of follicle-stimulating hormone (FSH) and luteinising hormone (LH) from the pituitary. These hormones, in turn, regulate the ovarian steroid hormone production. The first part of follicular development seems to be spontaneous but further development requires stimulation from FSH. As a result of high FSH levels estrogen production increases within the growing follicle shortly after menstruation has started. The estrogens reach the circulation and initiate growth and proliferation of the uterine mucosa, i.e. the endometrium, but also decrease FHS secretion by means of negative feedback on the pituitary and possibly also on the hypothalamus. Estrogen production increases enor-

Oral Contraceptives and Exercise

mously during the first 2 weeks of the cycle. At a certain level estrogens exert a positive feedback influence on LH, which is responsible for ovulation and the transformation of the follicle into a corpus luteum. Progesterone is thereafter produced in the corpus luteum in addition to its estrogen production. Progesterone prevents further proliferation and mitosis within the endometrium, but instead changes the mucosa to a secretory endometrium, ready for implantation of an early pregnancy. During this so called luteal phase the woman often experiences symptoms such as swelling and tenderness of the breasts and abdomen, and irritability, which may be referred to the hormonal changes, especially the rise in progesterone concentrations. If pregnancy does not occur, the corpus luteum ceases its progesterone and estrogen production. This leads to ischaemia, necrosis and shedding of the endometrium, a mensatrual bleed, which represents the end of one cycle and the beginning of the next. 1.2 Mechanisms of Action of Oral Contraceptives Oral contraceptives contain synthetic steroids with estrogenic and progestogenic effects, which inhibit pituitary FSH and LH production by means of negative feed-back. Follicular growth, ovulation and production of a corpus luteum is thus prevented, whereas the exogenous steroids in the pill induce endometrial growth and later shedding when intake is stopped, usually I week every fourth week. With the low doses of steroids contained in today's OCs follicular growth is not inhibited to the same degree as by older and more potent preparations, but ovulation is prevented as is the development ofthe corpus luteum. 1.3 Premenstrual Tension

1.3.1 Definitions and Symptomatology Cyclical mood changes are seen in 25 to 70% of all women of fertile age (Andersch et al. 1986; Backstrom et al. 1983). The premenstrual syn-

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drome (PMS) may be defined as when a woman has symptoms that begin at the time of ovulation or thereafter and improve significantly with the onset of menstruation and have resolved by the conclusion of the bleed (Pariser et al. 1985). It is important to establish the cyclicity of the symptoms, using daily recordings of symptoms over one or more cycles (Bancroft & Backstrom 1985). Features commonly associated with the PMS are irritability, mastodynia, bloating, cramps, headaches, insomnia, appetite changes, alterations in libido and fatigue (Bancroft & Backstrom 1985; Reid & Yen 1981). It seems reasonable to assume that some of these symptoms and alterations may influence the performance of daily activities as well as of various sporting activities.

1.3.2 Aetiology Several carefully executed studies have failed to show any differences in pituitary, gonadal or adrenal hormone levels between patients with PMS and control groups (cf. Bancroft & Backstrom 1985; Pariser et al. 1985; Rubinov et al. 1988). Recent data, however, have suggested that some women with PMS may experience periodic opioid withdrawal in the central nervous system, resulting in decreased ,8-endorphin levels and increased noradrenaline (norepinephrine) activity (Giannini et al. 1988). Clonidine decreases the amount of noradrenaline released at presynaptic sites and may explain its beneficial effect in women with PMS, compared to placebo (Giannini et al. 1988). 1.3.3 Treatment Numerous studies have failed to show single effective treatment regimens for PMS. It seems, however, as though prevention of ovulation and the development of the corpus luteum may be effective (Bancroft & Backstrom 1985). This may be achieved by the use of peroral contraceptives, longacting GnRH-analogues or danazole. Surveys have tended to find a lower incidence ofPMS in OC users than among non-pill users (e.g. Andersch & Hahn 1981; Herzberg & Copper 1970; Mears & Grant 1962; Moose 1968; Nilsson & SolveIl 1967). This may indicate a beneficial or pro-

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tective effect of OCs on PMS, but may also reflect the exclusion of women with PMS unable to tolerate OCs (Bancroft & Backstrom 1985). It has been concluded that the effect of OCs on PMS is unpredictable and unclear, and that some women may benefit, whereas others are made worse (Bancroft & Backstrom 1985). A luteinising hormone-releasing hormone agonist, inducing anovulation, has been shown to alleviate PMS in an open (Bancroft et al. 1987) as well as a placebo-controlled study (Hammarback & Backstrom 1988). Exercise as such has been found to improve PMS, especially such symptoms as headache, backache, cramps and anxiety (Norris & Sullivan 1983). This has been suggested to be due to neurotransmitter changes causing decreases in GnRH pulse frequency or due to increased central ,8-endorphin levels (Prior & Vigna 1987; Read & Yen 1983).

2. Influence of the Menstrual Cycle on Performance and Risk for Injury Investigations dealing with the influence of the menstrual cycle on performance are, on the whole equivocal. Many authors have suspected that performance during the menstrual period may well be influenced by psychological factors due to a negative attitude towards menstruation (e.g. Erdelyi 1962). The risk for general accidents (Dalton 1960a) as well as suicidal attempts and hospitalisation (Dalton 1959; Lutter & Cushman 1982) has been reported to be increased during the menstrual period. It has also been reported that women perform tasks less efficiently during certain phases of the menstrual cycle (Dalton 1960b, 1968; Pierson & Lockhart 1963). Slade and Jenner (1980) reported a small association between actually experiencing symptoms during the menstrual cycle and decrement in performance, especially with increasing difficulty of task. 2.1 In Sports In a study of 729 athletic women Erdelyi (1962) found an increased risk for injury during menstruation. A similar high risk for injury has also

Sports Medicine 12 (3) 1991

been reported during the menstrual period (Doring 1963). Ingman (1953) interviewed 107 female Olympic champions in various sports (gymnastics, swimming, basketball, athletics, winter sports) and reported that 39 women considered their performance to be decreased during menstruation, while 20 women considered performance to be increased during menstruation. Using a series of fitness tests, optimal performance and coordination occurred in the intermenstrual phase and the poorest during the menstrual period (Shangold 1980; Wearing et al. 1972). In a study in 23 young women students, physical fitness was tested daily (Bockler 1970). Administration of OCs cancelled the premenstrual fall in physical fitness which was observed during the normal menstrual cycle. Thus a series of observations indicate that performance varies during the menstrual cycle and the question arises as to the explanation for this variation.

2.2 Possible Mechanisms

2.2.1 Neuroendocrine Mechanisms Ovarian steroids have effects on cerebral function (Backstrom et al. 1984). These effects may be mediated via intracellular receptors, through interaction with monoamine turnover and metabolism or through direct effects on nerve membranes (cf. Backstrom et al. 1984). Progesterone in large doses can induce anaesthesia in animals and humans and increases the electroshock seizure threshold (Backstrom et al. 1984). Progesterone may thus have important effects on certain abilities essential for performance, such as neuromuscular coordination, reaction time etc. Accordingly, it has been shown that manual dexterity varies during the menstrual cycle, being decreased premenstrually when the serum progesterone concentrations are high and during the menstrual phase (Loucks & Thompson 1968; Stocker 1974; Wearing et al. 1972), especially amongst women with premenstrual symptoms (Posthuma et al. 1987).

Oral Contraceptives and Exercise

2.2.2 Effects on Ventilation Progesterone has been implicated as an agent causing hyperventilation in pregnancy and during the luteal phase. It is conceivable, therefore, that the endogenous surge of progesterone in the luteal phase could stimulate a ventilatory drive during exercise. Since there is a high correlation between low ventilatory drive and outstanding athletic performance in runners and swimmers (Byrne-Quinn et al. 1971; Saunders et al. 1976), a progestational effect on ventilation could be deleterious to maximal performance. Schoene and coworkers (1981) concluded that women during the luteal phase have augmented ventilatory responses to hypoxia and hypercapnia that induce an increase in ventilation during exercise. This increase in ventilation does not seem to affect adversely the exercise performance of trained athletes, whereas nonathletic controls were unable to reach as high a level of exercise during the luteal phase as they were during the follicular phase. Weight gain associated with water retention is observed during the luteal phase, probably due to progestational effects (Redgrove 1971). This causes discomfort felt in the breasts and dragging in the abdomen which is probably a disadvantage for sporting activities (Redgrove 1971). 2.2.3 Effects on Haemoglobin Concentration In women using OCs blood loss and risk of anaemia is less than among nonusers. Approximately 40% of women aged 20 to 50 have been estimated to show signs of iron deficiency (Aftergood & Alfin-Slater 1980). Women lose about Img of iron per day through the urine, faeces and sweat and 0.5mg per day as menstrual blood. Adult women who consume 2000 kcal/day replace only 1.2mg iron on an average American diet, which causes depletion of her iron stores after about 8 to 10 years (Haymes 1980). There is considerable evidence that anaemia has a detrimental effect on performance (Haymes 1980). Even mild anaemia is associated with decreased work output, although not all studies agree. Furthermore, anaerobic metabolism will commence at an earlier stage in an anaemic state and muscles performing anaerobic work are more

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Table I. Traumatic injuries among 84 women soccer players in relation to cycle phase and premenstrual symptoms (from MOilerNielsen & Hammar 1989) Premenstrual symptom

n

PM/R

Statistical significance PM VB R

All players

84

40/22

Sports injuries and oral contraceptive use. Is there a relationship?

LEADING ARTICLE Sports Medicine 12 (3): 152-160, 1991 0112-1642/91 /0009-0152/$04.50/0 © Adis International Limited. All rights reserved. SP0145A Sp...
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