Serum hormones and strength development during strength training in middle-aged and elderly males and females

Effects of a 12-week progressive strength training period on serum concentrations of testosterone, Cortisol and sex-hormone-binding globulin (SHBG) as well as on strength development of the leg extensor muscles were investigated in nine middle-aged males (M50; range 44–57 years) and in nine middle-aged females (F50; range 43–54 years) as well as in 10 elderly males (M70; range 64–73 years) and in 11 elderly females (F70; range 66–73 years). Substantial increases took place in maximal isometric strength during the 12-week training period both in M50 (from 2834 ±452 to 3941 ±772 N; P < 0.001) and in F50 (from 2627±725 to 3488± 1017 N; P < 0.001) as well as in M70 (from 2591 ±736 to 3075±845N; P < 0.01) and in F70 (from 1816 ± 427 to 2483 ±408 N; P< 0.001). The relative increases in strength during the 12-week training period did not differ significantly between the groups. However, during the last 4 weeks of the training none of the groups demonstrated further increases in strength but it actually decreased in F50 (P < 0.05), M70 (P < 0.01) and in F70 (P < 0.05). No systematic changes were observed during the training in the mean concentrations of serum total testosterone, free testosterone, Cortisol, and SHBG, nor in testosterone/ Cortisol and testosterone/SHBG ratios. However, the individual levels of serum testosterone and testosterone/cortisol ratio and the individual changes in strength during the last four most intensive training weeks of the 12-week period were in significant positive linear correlation in F70 (r = 0.57; P < 0.05) and in M70 (r = 0.61; P < 0.05). The present findings demonstrate that considerable gains may take place in strength during progressive strength training both in middle-aged and elderly people. The findings also point out the importance of the anabolic hormonal level for the trainability of muscle strength of an individual during prolonged strength training especially in elderly males and females. This indicates a need to plan strength training programmes carefully with regard for to the overall volume and the length of each training period to optimize the training process in elderly people both in preventive purposes and in rehabilitation.     

Neuromuscular adaptations during bilateral versus unilateral strength training in middle-aged and elderly men and women

Twelve middle-aged men and 12 middle-aged women in the 50-year-old age group (M50; range 44–57 years; W50; 43–57), and 12 elderly men and 12 elderly women in the 70-year-old age group (M70; 59–75; W70; 62–75) volunteered as subjects in order to examine effects of 12-week progressive heavy resistance strength training on electromyographic activity (EMG), muscle cross-sectional area (CSA) of the quadriceps femoris and maximal concentric force in a one repetition maximum (1 RM) test of the knee extensor muscles. One half of the subjects in each group performed the knee extension (and flexion) exercises only bilaterally (BIL), while another half performed the exercises only unilaterally (UNIL). None of the subject groups demonstrated statistically significant changes in any of the 1 RM values during the 2 week control period with no training (between week -2 and 0) preceding the actual experimental training. However, the 12-week training resulted in increases (P<0.05–0.001) in 1 RM values in each group so that the average relative increase of 19±12% (P<0.001) in bilateral 1 RM in all BIL trained subjects was greater (P<0.05) than that of 13±8% (P<0.001) recorded for all UNIL trained subjects. The average relative increases of 17±11% (P<0.001) and 14±14% (P<0.001) in unilateral 1 RM values of the right and left leg in all UNIL trained subjects were greater (P<0.05) than those of 10±18% (P<0.001) and 11±11% (P<0.001) recorded for all BIL trained subjects, respectively. The relative average increase of 19±19% (P<0.001) observed in the maximum averaged IEMG of both legs during the bilateral actions in all BIL trained subjects was greater (P<0.05) than that of 10±17% (P<0.05) recorded for all UNIL trained subjects. The relative increases of 14±12% (P<0.001) and 11±6% (P<0.001) recorded for the CSA in all BIL and UNIL trained subjects did not differ significantly from each others. The present findings suggest that progressive heavy resistance strength training leads to great increases in maximal dynamic strength of the trained subjects accompanied by both considerable neural adaptations and muscular hypertrophy not only in middle-aged but also in elderly men and women. Both bilateral and unilateral exercises are effective to produce functional and structural adaptations in the neuromuscular system, although the magnitude of functional strength increase seems to be specific to the type of exercise used, further supporting the principle of specificity in the design of strength programmes.     

Muscle strength and functional capacity in 78–81-year-old men and women

Summary Muscle strength was measured in 23 men and 29 women regarded as representative of the healthy urban population of about 80 years of age. Isometric and isokinetic strengths of right knee-extension, plantar, and dorsal flexion, and the isometric strength of some upper extremity functions were measured. For knee-extension there was a decrease in strength of about 30% from the values in a population study of 70-year-old subjects (Aniansson et al. 1980). Muscle strength was significantly lower in women than in men in all muscle groups except for plantar and dorsal flexion of the foot. Body cell mass was reduced compared to younger age groups by about the same extent as muscle strength, and correlated to knee-extension and hand grip strengths.Functional examinations such as step tests and walking tests were performed. A correlation between the results of these tests and muscle strength was not found except for knee-extension at 60 degrees/s in men. The rather low speed in comfortable walking (men 1.0 m·s^–1, women 0.9 m·s^–1) and the reduced capacity for step climbing diminish the possibility of using public transport and pedestrian street intersections in relatively healthy old people.     

Muscle hypertrophy,hormonal adaptations and strength development during strength training in strength-trained and untrained men

Hormonal and neuromuscular adaptations to strength training were studied in eight male strength athletes (SA) and eight non-strength athletes (NA). The experimental design comprised a 21-week strength-training period. Basal hormonal concentrations of serum total testosterone (T), free testosterone (FT) and cortisol (C) and maximal isometric strength, right leg 1 repetition maximum (RM) of the leg extensors were measured at weeks 0, 7, 14 and 21. Muscle cross-sectional area (CSA) of the quadriceps femoris was measured by magnetic resonance imaging (MRI) at weeks 0 and 21. In addition, the acute heavy resistance exercises (AHRE) (bilateral leg extension, five sets of ten RM, with a 2-min rest between sets) including blood samples for the determination of serum T, FT, C, and GH concentrations were assessed before and after the 21-week training. Significant increases of 20.9% in maximal force and of 5.6% in muscle CSA in NA during the 21-week strength training period were greater than those of 3.9% and −1.8% in SA, respectively. There were no significant changes in serum basal hormone concentrations during the 21-week experiment. AHRE led to significant acute decreases in isometric force and acute increases in serum hormones both at weeks 0 and 21. Basal T concentrations (mean of 0, 7, 14 and 21 weeks) and changes in isometric force after the 21-week period correlated with each other (r=0.84, P<0.01) in SA. The individual changes in the acute T responses between weeks 0 and 21 and the changes in muscle CSA during the 21-week training correlated with each other (r=0.76, P<0.05) in NA. The correlations between T and the changes in isometric strength and in muscle CSA suggest that both serum basal testosterone concentrations and training-induced changes in acute testosterone responses may be important factors for strength development and muscle hypertrophy.     

Effects of strength and endurance training on isometric muscle strength and walking speed in elderly women

The separate effects of 18 weeks of intensive strength and endurance training on isometric knee extension (KE) and flexion (KF) strength and walking speed were studied in 76-to 78-year-old women. Maximal voluntary isometric force for both KE and KF was measured in a sitting position on a custom-made dynamometer chair at a knee angle of 60° from full extension. Maximal walking speed was measured over a distance of 10 m. The endurance-trained women increased KE torque and KE torque/body mass after the first 9 weeks of training when compared with the controls. When comparing the baseline, 9 week and 18 week measurements within the groups separately, both the endurance- and strength-training groups increased KE torque, KE torque/body mass and walking speed. Individual changes in KE torque/body mass before and after 18 weeks of training averaged 19.1% in the strength group, 30.9% in the endurance group and 2.0% in the controls. This study indicates that in elderly women the effects of physical training on muscle strength and walking speed occur after endurance as well as strength training. The considerable interindividual variation in change of muscle performance is also worth noticing.     

Muscle strength according to level of physical exercise and educational background in middle-aged women in Finland

Summary The aim of this study was to examine the role of socio-economic status and the practice of physical exercise in explaining variation in muscle strength in 50 to 60-year-old women. Consequently, four study groups combining education and physical activity were formed: (1) university education, physically active; (2) university education, sedentary; (3) vocational or lower level of education, physically active; (4) vocational or lower level of education, sedentary. Maximal isometric strength of hand grip, arm flexion, body flexion and extension as well as dynamic power of the abdominal muscles were measured in 112 women. The results of the maximal isometric strength measurements were standardised by body mass index. The means of the maximal isometric strength results and sit-up tests were compared between the groups using two-way analysis of variance. The physically active women performed better than the sedentary in both the isometric and dynamic tests. Greater muscle strength was also found among the more highly educated compared with the less educated. The less educated sedentary women showed the poorest performance in the strength tests.     

Cardiovascular and muscular adaptations to combined endurance and strength training in elderly women

Twenty-one women aged 60–75 years were examined to determine whether combined endurance and strength training resulted in greater increase in peak oxygen consumption, sub-maximal time to fatigue, cardiac output, stroke volume, and leg extension load when compared to endurance training alone. Subjects in both the endurance training (E) and endurance and strength (E & S) groups trained 3 days a week, for 12 weeks, at an intensity of 70–80% V˙O ₂ peak for 30 min on a cycle ergometer. Subjects in the E & S groups also used resistance equipment to train the knee extensors. The workload for resistance training was based on an initial assessment of 10 repetitions maximum (10 RM), with 80% of that value used for training, three times weekly. Peak oxygen consumption increased to an average of 24.8 and 29.9% in the E and E & S groups, respectively, with no difference between groups. Subjects in the E & S and E groups significantly increased sub-maximal endurance time by 396 and 165%, respectively. Cardiac output, stroke volume, and arteriovenous oxygen difference at 80% peak V˙O ₂ were unchanged by either of the training methods. A needle biopsy was taken from the vastus lateralis before and after 12 weeks of training. Chi-square analysis of fibre area data showed an increase in the frequency of larger type I fibres in the post-training data from the E & S group, but an increase in the frequency of smaller fibres in the E group post-training; however, mean fibre area was not significantly changed by training. These data suggest that greater improvements in sub-maximal time to fatigue and strength is achieved when resistance training is added to an aerobic training programme in healthy elderly women.     

Reproducibility of isokinetic leg strength and endurance characteristics of adult men and women

Summary Day-to-day variability and single-measurement reliability of selected isokinetic knee extension-flexion strength and endurance indices were assessed in 10 adult men and 8 adult women. On three occasions separated by at least 5 days, the subjects completed 4 reciprocal maximal voluntary contractions (MVC) at different angular velocities (1.05 rad · s^–1 and 3.14 rad · s^–1). The men also completed a muscular endurance test consisting of 30 reciprocal, MVC at 3.14 rad ·^–1. Coefficient of variation, intra-class correlation coefficient and standard error of single-measurement scores support the continued use of gravity corrected peak torque (PT) and average peak torque (APT) as indices of isokinetic leg strength. Similarly, gravity corrected APT and total work should be the recommended indices of isokinetic leg muscular endurance in men. The results suggest that these isokinetic indices must be assessed using multiple day-to-day trial protocols adequately to describe performance capacity. Composite indices such as the ratio of Knee flexion to extension PT and fatigue measurements offer considerably reduced reliability and a greater potential for misinterpretation. The reliability of knee extension indices generally exceeds that of flexion indices. Similar variability and reproducibility of responses were observed between men and women and between reciprocal contractions performed at angular velocities of 1.05 rad · s^–1 and 3.14 rad · s^–1.     

Low serum testosterone and frailty in older men and women

Background

Frail older persons are at high risk of morbidity and mortality, and are characterized by body composition alterations. Serum testosterone, which regulates body composition, declines with age. We investigated the relation between serum testosterone level and physiological frailty in both older men and women.

Methods

This was a cross-sectional study of 108 adults 65 years old or older. Frailty status was determined by hand-grip strength, weight change, walking speed, exhaustion, and activity levels, and was classified as frail (3 or more deficits), pre-frail (1 or 2 deficits), or robust (no deficit) according to the Fried criteria. Serum total testosterone (TT) and sex-hormone-binding globulin were measured while free testosterone (FT) was estimated.

Results

Median (range) TT and FT were lower in frail than in pre-frail and robust men (TT: (frail) 15.7 [2.4–26.9] vs. (pre-frail) 19.4 [7.2–39.9] and (robust) 25.9 [13.2–35.2] nmol/L, P = 0.03; FT: 230.0 [35.9–299.0] vs. 272.0 [86.7–411.0] and 303.0 [267.0–396.0] pmol/L, P = 0.02) and women (TT: 0.31 [0.10–0.51] vs. 0.47 [0.14–1.55] and 0.45 [0.36–1.25] nmol/L, P = 0.02; FT: 4.59 [0.46–6.63] vs. 4.66 [1.57–15.10] and 6.65 [3.91–21.00] pmol/L, P = 0.03). After adjusting for age, comorbidities, body mass index, and serum albumin in ordinal logistic regression model, odds ratios of being frail were significantly higher for those participants whose TT and FT levels were in the lowest tertile compared to the highest tertile in men (TT: odds ratio [OR] 3.29, 95% confidence interval [CI] 1.14–9.50; FT: OR 3.44, 95% CI 1.05–11.22) and in women (TT: OR 6.69, 95% CI 1.84–24.31; FT: OR 4.86, 95% CI 1.31–18.08).

Conclusions

Low serum testosterone levels were independently associated with frailty in the elderly Taiwanese.     

Testosterone, SHBG and differential white blood cell count in middle-aged and older men

Objective

Low-grade chronic inflammation is increasingly being implicated in cardiovascular disease (CVD) etiology and may represent an alternative pathway through which testosterone and sex hormone-binding globulin (SHBG) influence CVD risk. We examined the associations between endogenous testosterone, SHBG and total and differential white blood cell (WBC) counts in men.

Methods

Cross-sectional study of 2418 men aged 40–78 years from the Norfolk population of European Prospective Investigation into Cancer (EPIC-Norfolk) who had no history of CVD or cancer and complete data on sex hormones (total testosterone (TT), SHBG and free testosterone (FT)) and WBC counts. Associations between sex hormones and WBC counts were assessed using linear regression models.

Results

Higher SHBG and TT levels were associated with lower WBC counts. After adjustment for age, BMI, smoking, physical activity and diabetes status, total WBC count decreased by 0.163 (95% CI −0.236; −0.091) and 0.102 (−0.170; −0.034) per standard deviation (SD) increase in SHBG and TT respectively. Associations of SHBG and TT with total WBC count were mainly accounted for by a lower granulocyte count (β coefficient = −0.132 (−0.194; −0.070) per SD increase in SHBG and β coefficient = −0.104 (−0.161; −0.046) per SD increase in TT). No associations between FT and total and differential WBC counts were found.

Conclusions

Endogenous TT and SHBG levels are inversely associated with total WBC and granulocyte count in middle-aged and older men. Even though the underlying mechanism and causal directionality requires further exploration, these results support a link between hormonal status and low-grade inflammation.     

Maximal strength and power characteristics in isometric and dynamic actions of the upper and lower extremities in middle-aged and older men

Muscle cross-sectional area of the quadriceps femoris (CSA_QF), maximal isometric strength (handgrip test and unilateral knee extension/flexion), the shape of isometric force–time curves, and power–load curves during concentric and stretch–shortening cycle (SSC) actions with loads ranging from 15 to 70% of one repetition maximum half-squat (1RM_HS) and bench-press (1RM_BP) were examined in 26 middle-aged men in the 40-year-old (M40) (mean age 42, range 35–46) and 21 elderly men in the 65-year-old age group (M65) (mean age 65, range 60–74). Maximal bilateral concentric (1RM_HS and 1RM_BP), unilateral knee extension (isometric; MIF_KE and concentric; 1RM_KE) strength and muscle CSA in M65 were lower (P < 0.001) than in M40. The individual values of the CSA_QF correlated with the individual values of maximal concentric 1RM_HS, 1RM_KE and MIF_KE in M65, while the corresponding correlations were lower in M40. The maximal MIF_KE value per CSA of 4.54 ± 0.7 N m cm^–2 in M40 was greater (P < 0.05–0.01) than that of 4.02 ± 0.7 N m cm^–2 recorded in M65. The maximal rate of force development of the knee extensors and flexors in M65 was lower (P < 0.01–0.001) and the heights in squat and counter-movement jumps as much as 27–29% lower (P < 0.001) than those recorded in M40. M65 showed lower (P < 0.001) concentric power values for both upper and lower extremity performances than those recorded for M40. Maximal power output was maximized at the 30–45% loads for the upper extremity and at the 60–70% loads for the lower extremity extensors in both age groups. Muscle activation of the antagonists was significantly higher (P < 0.01–0.001) during the isometric and dynamic knee extension actions in M65 than in M40. The present results support a general concept that parallel declines in muscle mass and maximal strength take place with increasing age, although loss of strength may vary in both lower and upper extremity muscles in relation to the type of action and that ageing may also lead to a decrease in voluntary neural drive to the muscles. Explosive strength and power seem to decrease with increasing age even more than maximal isometric strength in both actions but power was maximized at the 30–45% loads for the upper and at the 60–70% loads for the lower extremity action in both age groups. High antagonist muscle activity may limit the full movement efficiency depending on the type of muscle action, testing conditions and the velocity and/or the time duration of the action, especially in the elderly.     

Serum cortisol concentration and testosterone to cortisol ratio in elite prepubescent male gymnasts during training

Summary Serum cortisol concentrations and testosterone: cortisol concentration ratios of eight prepubescent elite male gymnasts (mean age 10 years 11 months) and 11 controls (mean age 11 years 1 month) were examined during 5 consecutive training days. During this period, the gymnasts trained 3 h each day with moderate intensity mobility, strength and skill exercises while the controls were relatively sedentary. Blood samples were taken from all the boys in both groups before (1630 hours) and 30 min after (2000 hours) training on 4 days. Serum cortisol concentrations of the gymnasts were not significantly different from those of the controls throughout the experiment. Serum cortisol concentrations of both groups were significantly larger (P<0.05) at 1630 hours than at 2000 hours, indicating that cortisol secretion followed the typical adult circadian change, seemingly unaltered by training. However, there was a significant decrease (P<0.05) in the testosterone: cortisol ratio of the gymnasts when compared with controls from day 1 to day 3. After a rest on day 4 the testosterone: cortisol ratio of the gymnasts significantly increased (P<0.05) but the ratio of the control group also increased indicating that there may have been some day-to-day change by factor(s) other than training. The most obvious factor which may have accounted for the unresponsiveness of serum cortisol concentration to the gymnastics training was that the exercise intensity was too low. However, several days of the training seemed to reduce the anabolic to catabolic balance but further experiments are needed to confirm this finding.     

中、老龄男性血清睾酮和皮质醇含量变化规律的研究

目的：研究中老年男性血清睾酮和皮质醇含量变化及规律。方法：５８１例４０岁以上健康男性以每１０年为一年龄组,分为４组。以２０～３９岁健康男性１１０例作为对照组。均于上午８～１０时静脉采血,分离血清,应用放免分析方法检测血清睾酮和皮质醇含量。结果：（１）４０岁以上各组血清睾酮含量与年轻组比较明显下降（Ｐ＜００１）,血清皮质醇含量逐渐增加,与对照组比较均差异显著（Ｐ＜００１）;（２）血清睾酮与皮质醇含量呈显著负相关（ｒ＝－０．３０９６,Ｐ＜００１）。结论：随增龄睾丸的内分泌功能逐渐下降,而肾上腺皮质功能则发生与之相反的变化     

Value of endometrial biopsies and serum hormone determinations in women with infertility

Premenstrual endometrial biopsies were performed in 324 infertile women. Their hormonal status was established in the early follicular phase of the same cycle (FSH, LH, oestradiol-17 beta, testosterone, DHEAS, TSH and prolactin, the latter two both basally and following TRH stimulation). In the luteal phase, oestradiol-17 beta and progesterone concentrations were determined three times between the fifth and tenth hyperthermic days, as was prolactin, both basally and following metoclopramide stimulation. All pregnancies occurring before January 1986 were recorded. Seventy-five per cent of the biopsies were evaluated on the expected ovulation date from the basal temperature charts, 77% according to the next onset of menstruation. Twenty-six per cent of the biopsies were out of phase, and 7% displayed abortive secretion. A significant correlation existed between endometrial profiles and the characteristics of the cycle, stimulated TSH and prolactin levels, and with testosterone and FSH concentrations. No correlation of the endometrial status with midluteal oestradiol or progesterone concentrations was found. While various hormones of both the follicular and luteal phases correlated significantly with the pregnancy rate, the same was not demonstrated for the state of endometrial biopsy. Therefore, following exclusion of organic explanations of infertility in women with biphasic cycles, the determination of progesterone and oestradiol-17 beta in the luteal phase was considered. In women with reduced concentrations of these hormones, androgens, gonadotrophins, prolactin and TSH should be determined. Endometrial biopsy is valuable only if pregnancy fails to occur, despite therapeutically normalized hormone concentrations.     

Effects of single macronutrients on serum cortisol concentrations in normal weight men

A previous study reported that a high carbohydrate meal, in contrast to a high protein/fat meal, significantly increased cortisol concentrations in visceral obese subjects. The objective of this study was to identify effects of single macronutrients on plasma cortisol concentrations. Ten male subjects (age 27.3 ± 7.4 y, BMI 22.1 ± 1.7 kg/m²) were studied in a randomized crossover design on four days around lunchtime after consuming breakfast matched for daily energy requirements (DER 20%). For lunch they consumed one liter of a shake (DER 18%) containing either fat, protein or carbohydrate, with a raspberry taste and similar hedonic value (59 ±2 mm on a 100 mm VAS), using water as control. Serum cortisol concentrations were measured before lunch and during three hours following lunch. Baseline cortisol concentrations did not differ among treatments. The protein as well as the fat lunch caused a significant decrease in cortisol concentrations when compared to the carbohydrate lunch, and showed no difference from the control condition (p < 0.05). The cortisol response in the protein condition (AUC = 37,024 ± 3518 nmol/L min) and in the fat condition (AUC = 35,977 ± 3562 nmol/L min) were significantly smaller when compared with the cortisol response in the carbohydrate condition (AUC = 47,310 ± 3667 nmol/L min) (p < 0.03), but did not differ from the control condition (AUC = 32,784 ± 1683 nmol/L min) (Fig. 1). The cortisol response in the carbohydrate condition was significantly higher when compared with the response in the control condition (p < 0.004). We conclude that cortisol concentrations decreased after protein or fat intake, which was not different from control; this decrease was prevented by carbohydrate intake.     

The (TAAAA)n microsatellite polymorphism in the SHBG gene influences serum SHBG levels in women with polycystic ovary syndrome

BACKGROUND: Hyperandrogenaemia is a common feature of polycystic ovary syndrome (PCOS). The sex hormone-binding globulin (SHBG) gene was proposed as being a PCOS candidate gene. A possible influence of the microsatellite polymorphism (TAAAA)(n) in the SHBG gene on serum SHBG levels in PCOS patients was investigated. METHODS: One hundred and twenty-three PCOS patients and 110 age-matched controls were included in the study. Peripheral blood samples were obtained. Genotyping of the (TAAAA)(n) polymorphism in the SHBG gene was performed. Serum LH, FSH, SHBG and total testosterone concentrations were determined. RESULTS: SHBG alleles with 6-11 TAAAA repeats were found. None of the SHBG alleles or genotypes were present at a significantly more frequent rate in PCOS patients compared with controls. Serum SHBG levels were significantly lower (P < 0.001) in PCOS patients compared with controls and were found to be strongly influenced by the (TAAAA)(n) SHBG polymorphism, in both the PCOS (55.3%) and control (33.1%) groups of patients. CONCLUSIONS: The (TAAAA)(n) SHBG gene polymorphism might be an important predictor for serum SHBG levels and, consequently, for hyperandrogenaemic clinical presentation of PCOS.     

Muscle strength and body composition as determinants of blood pressure in young men

Summary The correlations of blood pressure to various indices of muscularity and fatness were studied in 183 young healthy men (mean age 19.7, SD 2.1 years). Systolic pressure showed significant positive correlations with body fat percentage, isometric strength of trunk extensors, body mass index, lean body mass, strength of leg extensors, heart rate, and the sum of four skinfolds. Diastolic pressure had significant positive correlations with body mass index, lean body mass, body fat percentage, sum of skinfolds, strength of leg extensors, strength of trunk extensors, and age. A stepwise selective multiple regression analysis for systolic pressure resulted in four significantly correlating variables: body fat percentage (p<0.001), heart rate (p<0.01), lean body mass (p< 0.05), and strength of trunk extensors per kg body weight (p<0.05). For diastolic pressure the analysis resulted in two explaining variables: body mass index (p<0.001) and age (p<0.05). In a regression equation with 13 variables the strength of trunk flexors was negatively correlated with diastolic pressure.It is concluded that both fatness and muscularity are factors related to blood pressure in young men. The muscularity effect is more clearly associated with trunk and leg extensor strength.     

Muscle fibre type distribution,muscle cross-sectional area and maximal voluntary strength in humans

The relationship between maximum voluntary concentric strength, muscle fibre type distribution and muscle cross-sectional areas were examined in 23 subjects (7 female and 11 male phys. ed. students as well as 5 male bodybuilders). Maximal knee and elbow extension as well as elbow flexion torque at the angular velocities 30, 90 and 180 degrees per second was measured. Muscle biopsies were taken from vastus lateralis and m. triceps brachii. The muscle cross-sectional area of the thigh and upper arm was measured with computed tomography scanning. The maximal torque correlated strongly to the muscle cross-sectional area times an approximative measure on the lever arm (body height). Maximal tension developed per unit of muscle cross-sectional area did not correlate significantly with per cent type I fibre area and did not differ between the female and male students or bodybuilders. Neither did the relative decrease in torque with increasing contraction velocity show any significant relationship to the per cent type I fibre area. The total number of muscle fibres was estimated by dividing the muscle cross-sectional area with the mean fibre area of m. triceps brachii. The number of fibres did not seem to differ between the sexes.