Review Article

Sports Medicine 9 (4):·216-228. 1990 0112-1642/90/0004-0216/$06.50/0 © ADIS Press Limited All rights reserved. SPORT2271

Strength Training for Female Athletes A Review of Selected Aspects Jean Barrett Holloway and Thomas R. Baechle Department of Kinesiology, UCLA Extension, Los Angeles, California, and Department of Physical Education and Exercise Sciences, Creighton University, Omaha, Nebraska, USA

Contents

Summary ................ ........................................................... .................... ..................................... 216 I. Influence of Belief Systems on Strength Performance ..... .............. ....................................217 2. Strength Development: Comparisons Between the Sexes .................................................. 217 2.1 Anatomical Comparisons ............................................................................................... 217 2.2 Absolute Strength Comparisons .................................................. .................................. 218 2.3 Relative Strength and Power Comparisons ..................................................................219 2.4 Female Genetic Potential Versus Average Development ........................ .................... 220 3. Responses of Women to Strength Training ......................................................... ...............221 3.1 Limitations of Existing Research .................................................................................. 221 3.2 Musculoskeletal Responses ................................................. ...........................................221 3.3 Body Fat Alterations ........ ......... .... ........................... ... ........ ................ .......... ............... ..223 3.4 Self-Concept Responses .............................................................. .................................... 224 3.5 Menstrual Cycle and Strength Training .............. .................... ..... ............. ..... ............... 224 4. Strength Training Programme Considerations ......................................... .......................... 225

Summary

Women and men respond to strength training in very similar ways from their individual pretraining baselines. Women on the average have smaller bodies than men, have less absolute muscle mass and smaller individual muscle fibers, and display approximately two-thirds of the absolute overall strength and power of men. In addition, children are enculturated to view strength as masculine, an outlook which has depressed the pursuit and performance of strength activities by women. However, unit for unit, female muscle tissue is similar in force output to male muscle tissue, and there is some evidence to support similar, proportional increases for the sexes in strength performance and hypertrophy of muscle fibre relative to pretraining status. Strength training can also provide beneficial alterations in bone, body fat and self-concept in women. There is no evidence that women should train differently than men, and training programmes should be tailored for each individual.

The interest among women in strength training activities has increased greatly over the last 15 years.

However, the acute and chronic responses of this form of training in women are not well known and/

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or understood because researchers have only recently begun to investigate them. The purpose of this manuscript is not to be all-encompassing, but rather to provide a review of current literature regarding selected aspects of strength training by women, with special emphasis on athletes. Strength training is considered here as the use of barbells, dumbbells, machines and other forms of resistance to promote physical strength and its subcomponents for the purpose of improving athletic performance. Weight-training pertains to the use of the same equipment to improve fitness levels and/or appearance.

1. Influence of Belief Systems on Strength Performance The beliefs and expectations we as individuals have about our behaviours, including the ability to perform feats of strength and power and the propriety of doing so, as well as the association of strength with masculinity, are things that we learn from a very early age as we interact with our environment (Huston 1983). They are powerful determinants for men and women in strength performance, so much so that there is evidence that, given an individual's biomechanical factors and physiological readiness at the time of performance, these psychological factors are the limiting factors in determining the expression of maximal strength (Ikai & Steinhaus 1961; Ness & Patton 1979; Shelton & Mahoney 1978; Wilkes & Summers 1984). Thus, it is appropriate to begin a paper on strength training for female athletes with a reminder that these beliefs are learned, neural factors which can affect strength training, athletic performance and the decision to pursue strength-oriented activities (for a discussion see National Strength and Conditioning Association 1989).

2. Strength Development: Comparisons Between the Sexes Other authors have reviewed the anatomical and anthropometric characteristics of the sexes which contribute to differences in physical performance

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(Asmussen 1973; Malina 1975, 1978, 1980; Wells 1985; Wells & Plowman 1983). Wells and Plowman (1983) and Wells (1985) stress that although there are some statistical differences between the average man and the average woman, there are many similarities between the sexes. They also point out that individuals are not average, and that the differences between 2 individuals of the same sex are often greater than differences between statistical averages of each of the sexes. This may serve to caution the practitioner to balance the following comparisons of group means with the unique attributes of the individual at hand. 2.1 Anatomical Comparisons This section addresses the more genetically governed factors involved in strength comparisons: skeletal factors, body size and composition, and muscle fibre type distribution. Boys have a longer period of growth than girls (Malina 1980), with the result that the average adult man is larger than the average woman; he is taller by some 10% and he weighs approximately llkg more and his body is about 13% fat while hers is about 24% (Wells & Plowman 1983). Sheer size is a factor even in simple measures of strength. There is a moderate (0.46 to 0.79) correlation between height, weight, and grip strength from childhood to college age for men and women, the correlations being lower in young college women than in adolescent and college age men (Malina 1980). During adolescence, the skeletal proportions change: boys' shoulders broaden relative to their hips, and girls' hips broaden relative to their waists and shoulders (Malina 1980). The broader shoulders of the adult male allow more muscle to be packed onto the skeletal frame and create a mechanical advantage for muscles acting on the shoulder; the result is that the most pronounced difference in average strength performance between the sexes is in shoulder-related strength (Stobbe 1982). The broader hips of adult women tend to increase the angle at which the femur articulates, resulting in a greater Q angle for women than for

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men (Glass 1985). It has been theorised that a greater Q angle may predispose women to knee injuries and/or make squatting movements more difficult for women than men (Roundtable 1985). Some experts, however, feel that muscle and ligament weakness in the knee is far more apt to lead to injuries than any anatomical predisposition, and that various squatting and leg extension movements are the best preventive measures, especially when special attention is given to the vastus medialis which balances the lateral pull on the patella (Roundtable 1985). It has also been speculated that because female leg length averages 51.2% of body height compared to 52% of body height for males (Wells 1985), these slightly shorter legs coupled with broader hips should give females a strength advantage in squatting exercises (O'Shea 1985). To date, however, these speculations favouring or not favouring innate female squatting ability remain unsupported by scientific evidence. It may be that individual body proportions are a better, although far from all-encompassing, indicator of squatting potential. Taken together, femur length, torso length and height accounted for approximately 77% of the variance in the ability of untrained women (Fry et a!. 1989) and men (Fry et a!. 1988) to squat flat footed. The most potent discriminator was femur length for women, but height for men. Additionally high level male and female powerlifters (Bale & Williams 1987) and high level male and female Olympic-style weight lifters (Liu et a!. 1987b), all of whom train and compete with squatting types of movements, tend to have shorter than average legs relative to height. The majority of studies dealing with relative muscle fibre type distribution between the sexes have shown few gender differences (National Strength and Conditioning Association 1989; Ryushi et a!. 1988; Saltin et al. 1977). There may be a tendency for men to have a greater fast twitch/slow twitch fibre area ratio, as exemplified by 2 studies which compared the vastus lateralis in physically active women, physically active men and male strength athletes. Schantz et al. (1983) gave ratios for these respective groups as 1.02 ± 0.08 (n = 7), 1.29 ± 0.08 (n = 11) and 1.51 ± 0.06

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(n = 5); Ryushi et al. (1988) reported 0.93 ± 0.19 (n = 10), 1.16 ± 0.25 (n = 9) and 1.30 ± 0.09 (n = 7) for their subjects, the values for women being significantly different from both groups of men. One possible explanation for this is a differ.. ence in physical activity habits as noted earlier by Saltin et al. (1977). There also appears to be a tendency for men to have greater extremes of fibre composition than women (Saltin et al. 1977), but the significance of this in strength performance is still uncertain (Maughan 1984; Ryushi et al. 1988). Men appear to have larger muscle fibres than women when fibre cross-sectional area is measured (Costill et al. 1916; du Plessis et al. 1985; MacDougall et al. 1983; Prince et al. 1977; Schantz et al. 1983), although one study comparing nationally ranked male and female bodybuilders showed no difference in fibre cross-sectional area (Grumbt et al. 1988). Comparisons between the sexes of the number of muscle fibres are equivocal in their results. A study using the triceps brachii found men and women to have equal numbers of fibres (Schantz et al. 1983). One study found equal numbers of fibres in the biceps brachii of nationally ranked male and female bodybuilders (Grumbt et a!. 1988), while another also using the bicep showed more fibres in untrained men than in untrained women (MacDougall et al. 1983). On the average, the major anatomical gender differences related to strength appear to be in height, weight, muscle fibre size and the proportions of hip to shoulder and body fat to bodyweight. 2.2 Absolute Strength Comparisons Although there is a great range and overlap of strength abilities in men and women, when the measure is the absolute amount of force exerted or weight lifted, the average woman is about two-thirds as strong as the average man. Laubach (1976) reviewed 9 descriptive studies, all but one of which used static measures of strength, and found absolute upper body strength in women was 35% to 79% (averaging 55.8%) that of men, while absolute lower body strength was 57% to 86% (averaging 71.9%)

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that of men; the mean percentage of women's total body strength was 63.5% that of men. Using measurements of functional torque, Stobbe (1982) found lower overall values than Laubach, women overall being 56.5% as strong as men. In another review, Hudson (1978) summarised absolute strength differences as: female upper body 50% to 60% as strong as the male's, and female lower body 70% to 80% as strong as the male's. Wilmore (1974) conducted one of the first experimental studies comparing responses of women and men to strength training and Hudson's (1978) analysis of the pretraining scores of Wilmore's subjects shows an overlap of female and male scores on all strength tests; Wells and Plowman (1983), in a similar analysis, show a large overlap for Wilmore's males and females in pretraining leg press scores. 2.3 Relative Strength and Power Comparisons Strength has been expressed relative to body mass, to lean body mass, and per unit of muscle cross-sectional area in studies comparing men and women. Morrow and Hosler (1981) compared female basketball and volleyball players with untrained men and found the men superior for both upper and lower body strength expressed both absolutely and relative to bodyweight and size. Using the same measurement techniques as Morrow and Hosler (1981), Bond et al. (1985) compared female bodybuilders to untrained men; they found the bodybuilders weaker in the upper body in absolute strength, but the same in absolute lower body strength, with no significant differences between the sexes for upper body or lower body strength relative to bodyweight and size. Komi and Karlsson (1978) found total isometric leg force in men and women almost identical when related to bodyweight. O'Shea and Wegner (1981) found women weaker in lRM bench press and squat than similarly experienced men, both absolutely and relative to bodyweight, both before and after 9 weeks of conditioning and weight-training in both groups. When Wilmore (1974) measured strength relative to lean body mass, thus eliminating the greater amount of body fat that women have, men still

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displayed greater upper body strength, but women slightly surpassed men in leg press strength. This parity of leg strength between the sexes, when expressed relative to lean body mass, was also found by Levine et a1. (1984). Hosler and Morrow (1982) used multiple regression techniques and found that once body composition and size were controlled, gender accounted for 1% of the variance in arm strength between the sexes, and 2% in leg strength. Heyward et a1. (1986) also used mUltiple regression techniques and reached a similar conclusion, that gender differences in upper and lower body strength are largely a function of differences in lean body mass, and the distribution of muscle and subcutaneous fat in the body segments. However, 27% of the variance in strength between the sexes remained unaccounted for in their study. It may be speculated that biomechanical factors such as leverage, and neural factors such as training background and expectations, would help explain this variance gap. Differences in strength have been negated between sexes, children of different ages, and groups of different training backgrounds when the force exerted has been calculated per unit cross-sectional area of muscle tissue (Davies et al. 1983; lkai & Fukunaga 1968; Grumbt et al. 1988; Sale et al. 1983; Schantz et al. 1983). lkai and Fukunaga (1968) reported that men and women (n = 245) ranging in age from 12 into the 20s shared a range of strength ability offrom 4 kgfcm 2 to 8 kgjcm 2 , with a mean of approximately 6 kgjcm 2 for both sexes. Men have displayed significant increases in the force exerted per cross-sectional unit of muscle tissue with training over approximately 14 weeks, from an initial mean of 6 kgjcm 2 to a final mean of 10 kgj cm 2 (Ikai & Fukunaga 1970). Since these subjects were measured in the same isometric mode in which they trained, specific neural adaptations to the mode of training help explain these increases (for a related discussion see Sale 1988). It should be noted that the lkai and Fukunaga (1970) subjects' absolute increases in strength were also related to a 23% increase in cross-sectional area of muscle.

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A recent study by Hakkinen et a1. (1989), apparently an extension of descriptive work reported by Ryushi et al. (1988), found significant differences (p < 0.01) in maximal force per unit crosssectional area of quadriceps femoris between male strength athletes (n = 7) and physically active females (n = 10) and males (n = 9), both before and after 10 weeks of intensive (70 to 100% 1RM) strength training. Significant differences between physically active males and females were found for lRM (kgfcm 2), but not maximal force (N/cm 2) by Ryushi et al. (1988). They speculate that these differences and those reported between men and women in the time taken to reach 30% of maximum force (women being significantly slower) may be influenced by sex hormones, training stimuli and daily activity patterns. The difference in force per unit muscle tissue between the 2 groups of men very likely reflects the male strength athletes' 5 to 10 years of high level training practices. The conclusion to be drawn from these muscle cross-sectional studies, taken together with the multiple regression studies, is that female muscle tissue, unit for unit, does not differ in potential force output from male muscle tissue. This indicates that the training potential and methods of training for men and women should be similar, although there have been doubters of this fact in the past (for a discussion see Hudson 1978). It is clear that the amount and location of muscle tissue on a given individual are major determinants of strength, and are important factors in explaining absolute strength differences between the sexes, since men typically have a larger amount of muscle mass than women, especially in the upper body. Comparisons of power between the sexes appear to have received less attention than comparisons of strength. Komi and Karlsson (1978) report presumably untrained women as having 68.3% of the absolute muscular power of men. Recent measurements by Garhammer (1989a) compared power outputs of winners at the first Olympic-style weight lifting championships for women with measurements taken on men in World and Olympic competition. Power outputs for complete pull phases of the snatch or clean are useful indicators of max-

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imal power (Garhammer 1989b), and results showed snatch power output per unit body mass was 22.5 ± 1.7 W/kg for women compared to 34.4 ± 2.5 W/kg for men. Thus, present maximum power output relative to body mass for females can be approximated at two-thirds, or 65% of the maximum relative power output for males, although relative power output may improve when calculated only from the explosive second pull phase of the lift. 2.4 Female Genetic Potential Versus Average Development Results in high level competition give an indication of what achievements in strength and power performance are possible for women with good athlete selection, timely and intelligent training, and high motivation. Since events which require strength and power, such as sprints, long jump, shotput, discus, and javelin, were introduced for women in World and Olympic Games competition, performance in them by female athletes has sharply improved, as reported by Malina (1978) and Wells (1985). Participation by women in sports that measure how much weight can be lifted is relatively new. To date, current official world records ofthe greatest weight in the overhead lift of the clean and jerk are 137.5kg for women (Li Hongling and Han Changmei both of China in 1989) and 266kg for men (Leonid Tarenenko of the USSR in 1988). Relative to bodyweight, the best jerks are approximately double bodyweight for women and triple bodyweight for men. Although female athletes continue to expand our conception of women's genetic potential in strength, poor strength performance is unfortunately still characteristic of adolescent girls (Raithel 1987). The 1986 Women's Sports Foundation Survey noted that the chief barrier to sport participation by women is lack of involvement and training as children (Women's Sports Foundation Survey 1986). It seems reasonable to conclude that without early and continuing positive exposure to strength-related activities during critical develop-

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mental periods, girls cannot be expected to approach their genetic potential in strength or power performance as they mature into adulthood.

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of future research in the field of strength and power enhancement. 3.2 Musculoskeletal Responses

3. Responses 0/ Females to Strength Training Much of the absolute difference in strength between males and females seems to be explained by absolute differences in the amount and location of muscle tissue, so it is not surprising that when ma1,es and females do participate in various types of weight-training, they respond in a very similar fashion. When response differences are observed, consideration of neural-related factors such as training background and the psychological interaction of the individual with the existing culture, biomechanical factors, and hormonal factors can offer insight. In addition, different styles of weighttraining elicit different responses. As each topic is presented in the sections to follow, an effort is made to provide descriptions of reported programme variables associated with a particular response. 3.1 Limitations of Existing Research Data is scarce about the long term effects on females of various types of heavy resistance exercise. At present, most data is only on men (for example, Tesch 1987). Many, though not all, of the research studies that do deal with females and weight-training have used untrained subjects and do not give sufficient details of the exercise regimen to allow replication. Furthermore, they tend to be of short duration (less than 20 weeks) and generally do not use the more demanding types of exercises, or the frequency, intensity, or variations in training that are currently in use by high level female strength and power athletes. Descriptive data (such as Armitage 1988) and accurate case studies of the training methods used to develop highly successful female Olympic-style weightlifters (such as Takano 1990), powerlifters, and track and field athletes are needed as guides to the interpretation

Bone, connective tissue, and muscle all have adaptive responses to strength training which are specific to the demands of training. Bone atrophies and loses its component minerals in the absence of weightbearing stress (Mazess & Whedon 1983), and conversely, bone hypertrophies and gains in mineral content in response to weightbearing physical activity. Recent studies show that postmenopausal women, who are more vulnerable to osteoporosis than premenopausal women, can use weightbearing exercise to maintain or increase bone mass (Dalsky et al. 1988; Oyster et al. 1984; Smith et al. 1984). The importance of physical activity in the prevention of osteoporosis has been reviewed by Smith and Gilligan (1987) and by Nutter (1986), who suggests that a buildup of bone mass through physical activity such as weight-training in the premenopausal years may minimise the loss of bone mass associated with ageing in women. A positive effect on bone mass from even moderate amounts of physical activity was found in a survey offemales ranging from 19 to 91 years of age by Stillman et al. (1989). Underscored here is the importance of establishing lifetime habits which adequately stress bones early in life. The principle of specificity of exercise adaptation when applied to bone is known as Woltrs law: bone tends to remodel according to the functional demands placed upon it (Woo et al. 1981). Thus, high level male and female tennis players have a thicker humerus in the playing arm than in the nonplaying arm (Jones et al. 1977). In a ranked listing of femur density in male athletes (Nilsson & Westlin 1971), weightlifters had the densest bones, followed by throwers, runners, soccer players, and swimmers; the athletes had denser bones than nonathletes, and active nonathletes had denser bones than those who did not exercise. A similar ranking of bone mineral content in the femoral neck and the lumbar spine was found for female

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athletes, bodybuilders having higher values than collegiate runners, swimmers, recreational runners and inactive controls; the difference between the body builders and the inactive controls on both measures was significant (Westfall et al. 1988). Corroborative arm bone density results are reported by Aulet et al. (1989) for male and female weighttrainers, runners and controls; additionally, males had denser arm bones than females, and runners of both sexes had the lowest arm bone density, presumably due to a lack of stress provided to the arms by running. These descriptive studies suggest that the bone mineral content achieved by bone is both a localised, specific response to a given exercise, and that it is proportional to the intensity of the weightbearing stress provided. A similar conclusion was reached in a review by Stone (1988). Stone (1988) has also reviewed the scant evidence regarding the effects of resistance training on tendons and ligaments, concluding that physical activity can increase connective tissue mass. Muscle tissue, like bone and connective tissue, atrophies with disuse and hypertrophies with use. Examination of individual muscle fibres obtained by needle biopsy demonstrates this in females. 1 Female hockey players were found to have larger SO, FOG and FG fibres in the vastus lateralis than untrained females (Prince et al. 1977), and mothers of severely disabled children were found to have larger type II bicep fibres than other females who presumably did not have to do as much lifting (Brooke & Engel 1969). Staron et al. (1989) report increases over pretraining measures in the cross sectional area oftype I (20%), type IIA (28%), and types IIAB + lIB (34%) leg muscle fibres in college age females following 20 weeks of weight-training. Their programme involved 2 warm-up sets and 3 sets of 6 to 8RM (to exhaustion, with 1 to 2 minutes rest between sets) in the back squat, leg press and leg extension, for an unreported frequency per week. Staron et al. (1989) also conclude that transformations occurred in fibre types IIAB to lIB to IIA as a result of training. The greater increase in I Fibre types are reported using the terminology of the original research.

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hypertrophy in fast twitch fibres compared with slow twitch agrees with training studies using men and descriptive studies of male Olympic-style weightlifters and powerlifters, as reviewed by Tesch (1987). Similarly, Bailey et al. (1987), who trained women for only 10 weeks, 4 days/week at 80% 1RM, found increases in the cross-sectional area of type lIB vastus lateralis fibres (21%, p < 0.05), and type IIA fibres (18%, p < 0.08). Since greater muscle hypertrophy gains occur after the first 8 weeks of training in novice trainers, the earlier strength gains being largely neural (Hakkinen 1985), the findings of Bailey et al. (1987) probably would have been greater if the study had been longer, but as they stand are in accord with the trend described by Staron et al. (1989). After strength training on the same routine, men have greater absolute increases in both strength and muscular hypertrophy than women, as reviewed by Cureton et al. (1988). However, studies comparing men and women placed on the same training routines have reported women achieving percentage changes in strength similar to men's in upper and lower body (Cureton et al. 1988), or greater percentage changes than men in isometric leg extension force (Hakkinen et al. 1989) and in the bench press, back squat, and leg press (O'Shea & Wegner 1981; Wilmore 1974). Likewise, recent studies using needle biopsy, ultrasound and computed tomography techniques show men and women experiencing similar changes in muscular hypertrophy relative to pretraining status. Percentage increases' in elbow flexor fibre size and in muscle cross-sectional area were found to be similar in men and women (Sale & O'Hagan 1987, cited by Cureton et al. 1988). Cureton et al. (1988) found significant increases for men (7cm 2 or 15%) and women (5cm 2 or 23%) in the crosssectional area of upper arm muscle by computed tomography; these increases were not significantly different from each other. Neither sex experienced muscle hypertrophy in the thigh. The training routine for Cureton et al. (1988) lasted 16 weeks, 3 sessions per week of 1 to 3 sets at 70% to 90% of 1RM, with a variety of machine and free weight exercises. Rest intervals were not reported. Finally,

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Hakkinen et al. (1989), using ultrasound techniques, found significant increases in the cross-sectional area of the quadriceps femoris in physically active females (+ 11.3%) and physically active males (+ 13.6%) following a 10-week strength training programme; and subjects trained every other day at 70 to 100% of lRM. Changes in body girths may be due to increases or decreases of muscle tissue and/or body fat. If fat is lost and muscle hypertrophies after short term strength training, girth and bodyweight may change only slightly, but the quality of the body's composition has improved; strength has also improved due to early neural adaptations and the beginning of hypertrophy alterations. This is probably the interpretation to give to the slight girth changes obtained for presumably previously untrained women in 9- to IO-week studies (e.g. Bailey et al. 1987; Capen et al. 1961; Mayhew & Gross 1974; Wilmore 1974), especially in light of findings of significant muscle fibre area increases by Bailey et al. (1987). The greater absolute hypertrophy increases in men but similar relative increases in men and women can be viewed as changes proportional to the pretraining size of the muscle fibres (as discussed in section 2.1), men typically having greater muscle fibre size than women (Cureton et al. 1988). Given the similar unit for unit force capability of male and female muscle tissue, similar relative strength improvements following training by men and women, and a strong link between the crosssectional area of muscle and the ability to produce force (Maughan 1984; Ryushi et al. 1988), proportional hypertrophy would be the logical expectation. The theory that women can make strength gains without any accompanying hypertrophy because they lack the same blood levels of testosterone as men (Roundtable 1985; Wells 1985) is not supported by the evidence just discussed concerning increases in fibre cross-sectional area in women. Although men have approximately 10 times the blood level of testosterone that women have (Weiss et al. 1983), the extent of influence of this hormone has been questioned (for a discussion, see National Strength and Conditioning Association 1989). In

addition, recent evidence indicates weight-trained women may have higher pre-exercise levels of total serum testosterone than untrained women, and that testosterone levels increase in women during a weight-training session (Cumming et al. 1987). It should be noted that the hormone responses of the subjects (n = 7) used by Cumming et al. (1987) were by no means uniform, once again emphasising the range of individual variation. Both men and women may have responses to exercise that are proportional to baseline levels of hormones. Weiss et al. (1983), using a half-hour machine circuit training routine, showed similar significant percentage changes for men and women in serum androstenedione, as well as significant testosterone increases in men (22%) and similar, but nonsignificant, testosterone increases in women (17%). Previous studies on serum androgen levels in weight-training women (Fahey et al. 1976; Westerlind et al. 1987) which showed minimal or no changes in testosterone levels may not have used a sufficiently demanding exercise routine, or may have missed changes due to the timing of their sample taking (Kraemer 1988). Hakkinen et al. (1989) found only minor changes in serum testosterone levels after physically active men, women and male strength athletes trained at 70 to 100% 1RM for 10 weeks. However, the women displayed greater interindividual differences and these levels were correlated with their individual changes in maximal force (r = 0.76, P < 0.05). To date, no clear picture of the hormonal aspects of intensive strength training has emerged. For further discussion of the possible complex links between hormones and anabolic: catabolic ratios such as testosterone: cortisol (whether originating naturally or not), and muscle size, muscle strength, and strength training, see Alen and Hakkinen (1987), Hakkinen (1985), Hakkinen et al. (1987, 1988), Kraemer (1988) and Wright and Stone (1985). 3.3 Body Fat Alterations The importance of body composition to strength and power performance is 2-fold: an increase in the amount of contractile muscle tissue provides greater

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potential for strength, and a reduction in the amount of body fat means less dead weight to carry in movements such as jumping and running. Although body fat data has been reported on female bodybuilders (Freedson et al. 1983; n = 10, mean = 13.2%), data on female Olympic-style weightlifters and powerlifters is only beginning to be collected. 200 high level Chinese female Olympic-style weightlifters, with an average age of 16.28 years and an average training history of 1.41 years, had body fat percentage averages (from skinfolds) ranging from 16.6% in the 44kg weight class up to 32.5% in the +82.5kg weight class. The average for all weight classes was 21.95 ± 6.88% (Liu et al. 1987b). By comparison a sample of 12 American male weightlifters of varying ability averaged 8.76 ± 4.78% body fat, as measured by underwater weighing (Stone et al. 1979). High level British female powerlifters (n = 9) averaging 26.7 years of age and 2.6 years of training were found to have lower skinfold sums than average women, indicating a lower body fat. Their circumferences were larger than the usual circumferences of sedentary women or female bodybuilders, indicating the presence of hypertrophy in shoulders, chest, and limbs (Bale & Williams 1987). Studies of untrained females participating in 9 to 10 weeks of weight-training typically show a decrease in body fat of 3 to 7% from initial levels (Hunter 1985; Mayhew & Gross 1974; Wilmore 1974) with almost no change in bodyweight. These descriptive and experimental studies document the favourable influence strength training can have on the body composition of women. 3.4 Self-Concept Responses Sports requiring aggression and strength tend to be considered unfeminine (Del Rey 1978; Metheny 1965; Snyder & Kivlin 1975; Snyder & Spreitzer 1973), yet women involved in strength and power sports such as powerlifting, track and field, and basketball have good feelings about themselves, as good or better than women participating in less socially stigmatised activities or those who do not participate (Jackson & Marsh 1986; Ramirez 1980;

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Snyder & Kivlin 1975). Female bodybuilders also present normal or favourable psychological profiles on traditional psychological instruments (Freedson et al. 1983; Fuchs & Zaichkowsky 1983); however, there is evidence that female participants in activities which emphasise leanness may be more vulnerable to negative eating disorders than ath~ letes whose sports do not emphasis leanness (Borgen & Corbin 1987). Participation in a strength activity may have an influence on self-esteem which is sufficiently strong to counter the negative influence of social stigma. Several studies have found a positive relationship between aspects of strength and weight-training and self-concept variables for men (Dishman & Gettman 1981; Gasser 1965; Tucker 1982, 1983a, 1983b, 1983c). To date, 4 studies have obtained similarly positive results using women who ranged in age from adolescence (Holloway et al. 1988) to college and middle age (Brazell-Roberts & Thomas 1989; Brown & Harrison 1986; Trujillo 1983). Taken together, these reports offer support for the notion that participation in weight-training can result in positive changes in self-concept and self-esteem for women of varying ages and abilities. 3.5 Menstrual Cycle and Strength Training Data is scarce on this topic, especially on highly trained strength athletes. A Chinese study (Liu et al. 1987a) of the menstrual cycle in 199 female Olympic-style weightlifters, with an average age of 16 years, reported 75% regular in their menses and 25% irregular, with few experiencing dysmenorrhoea, and 3 lifters aged 13 to 15 years who had not yet begun to menstruate. The authors conclude that female weightlifters have fewer problems with irregular menses than female swimmers or long distance runners. Of the total 199 lifters, 73 competed while menstruating; of these, 22 did not perform well, and the authors recommend that using artificial control of the menses (oral contraceptives or a progesterone injection) to avoid competing while menstruating would be of benefit to performance. However, a study of the dynamic strength and work capability of untrained, normally men-

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struating women during various stages of the menstrual cycle showed no discernable change in performance on an isokinetic leg machine (Dibrezzo et al. 1988). Wells (1985) points out that the influences upon menstrual symptomatology are many and varied, ranging from the psychological and cultural to the physiological, and that any woman experiencing menstrual discomfort should seek medical counsel. Given the present lack of data, it is difficult to draw any conclusions, except that further research and ethical debate on the subject are warranted.

4. Strength Training Programme Considerations As discussed, muscle tissue in females and males has the same training potential, and men and women have similar responses to strength training from their pretraining baselines. Thus, men and women should train in the same way. Programmes should be tailored to the individual. The goals of the individual should be analysed and the choices of exercises, intensities, and set, repetition, and rest period combinations, as well as variations needed in training, should be made to further those goals. Techniques of using these variables to enhance athletic performance are discussed at length elsewhere (for example, see Baechle 1984; Bompa 1983; Garhammer 1987; Roman 1986; Starr 1978; Stone & O'Bryant 1987; Takano 1987, 1988). It is sufficient to mention here that these experts and others (National Strength and Conditioning Association 1989) recommend that athletes use multijoint free weight exercises such as various full and partial snatching movements, cleaning movements, jerking and pressing movements, squatting movements, and lunging movements, because they demand movement patterns, and the neuromuscular coordination and speeds which relate well to real life sport requirements.

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Authors' address: Thomas R Baechle, Department of Physical Education and Exercise Sciences, Creighton University, Omaha, NE 68178, USA.