Contributions of force and velocity to improved power with progressive resistance training in young and older adults

We investigated the effects of age on changes in the force and velocity components of knee extension (KE) power during 16 weeks of traditional progressive resistance training (PRT). Thirty-one young (27 ± 1 years, 16 men, 15 women) and 30 older (64 ± 1 years, 14 men, 16 women) adults trained by KE, leg press, and squat 3 days/week. PRT consisted of three sets with an appropriate load for 8–12 repetitions to fatigue. Testing occurred at baseline, 8, and 16 weeks. Thigh lean mass (TLM) was measured by DEXA. KE load–power and load–velocity curves were generated from peak concentric contractions against loads equivalent to 20, 30, 40, 50, and 60% maximum voluntary isometric contraction (MVC) force. Quadriceps neural activation relative to maximum was assessed during a sit-to-stand task. Participants increased KE 1RM (P < 0.05) by 8 weeks with young adults also increasing strength from 8 to 16 weeks. Adjusting for TLM, all groups increased KE specific strength (P < 0.05). MVC improved by 8 weeks in older adults and by 16 weeks in young subjects (P < 0.05). Neural activation requirements during standing and sitting declined in older adults by 8 weeks (P < 0.05). The KE load–power curve improved for all groups (P < 0.05) by 8 weeks with only young adults improving from 8 to 16 weeks. Peak concentric velocity increased only in older adults (P < 0.05). Training improvements in power resulted primarily from increases in strength both early and late for young adults while older adults realized early improvements in both strength and peak concentric velocity. Grants: This study was supported by National Institute on Aging Grant R01 AG017896 (MMB), Department of Veterans’ Affairs Merit Grant (MMB), and General Clinical Research Center Grant M01 RR00032.     

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.     

Effects of prolonged low doses of recombinant human erythropoietin during submaximal and maximal exercise

The aim of this study was to characterise the effect of prolonged low doses of recombinant erythropoietin (r-HuEPO) on the responses to submaximal and maximal exercise. Volunteer recreational athletes (n=21) were divided into three groups: r-HuEPO+intravenous iron (EPO+IV, n=7), r-HuEPO+oral iron (EPO+OR, n=9) and placebo (n=5). During the 12 week study, r-HuEPO or saline injections were given three times a week for the first 8 weeks and for the final 4 weeks the subjects were monitored but no injections were administered. The r-HuEPO doses were 50 IU·kg^–1 body mass for 3 weeks and 20 IU·kg^–1 body mass for the next 5 weeks. An exercise test comprising three submaximal intensities and then increments to elicit maximal aerobic power ( ) was conducted during weeks 0, 4, 8 and 12. During week 0, the mean intensity of the submaximal stages was 60%, 72% and 81% . Blood taken at rest was analysed twice a week for haematocrit (Hct). The relative increases in at weeks 4, 8 and 12 were 7.7%, 9.7% and 4.5%, respectively, for the EPO+IV group; 6.0%, 4.7% and 3.1% for the EPO+OR group; and –0.5%, –0.1% and –1.0% for the placebo group, where the improvements at week 12 for the EPO+IV and EPO+OR groups remained significantly above week 0 values. The Hct was significantly elevated by 0.06 and 0.07 units at week 3 in the EPO+IV and EPO+OR groups, respectively, and was stable during the 5 weeks of low-dose r-HuEPO. After 8 weeks of r-HuEPO use, plasma lactate concentration tended to be lower at exercise intensities ranging from 60% to 100% . This study confirmed the ability of low doses of r-HuEPO to maintain Hct and at elevated levels. Electronic Publication     

Effects of altitude on the energetics of human best performances in 100 m running: a theoretical analysis

The present study was designed to investigate the role of reduced air density on the energetics of 100 m running at altitude. A mathematical supply-demand model was used where supply had two components, aerobic and anaerobic and demand had three components: the cost of overcoming non-aerodynamic forces (C_na), the cost of overcoming air resistance (C_aero), and the cost due to changes in the runner's kinetic energy (C_kin). Actual instantaneous-speed curves recorded in 100 m world champions were modelled at sea level. Then I calculated improvements in 100 m running times and changes in the components of the energy cost with changes in altitude from 0 m to 4,000 m. For the 100 m world championship for men, the model predicted times of 9.88 s at sea level, 9.80 s at 1,000 m, 9.73 s at 2,000 m, 9.64 s at 4,000 m and 9.15 s in the hypothetical situation where the air resistance was nil. In the counterpart for women the corresponding times were 10.85 s, 10.76 s, 10.70 s, 10.60 s and 10.04 s. The C_aero was 12%–13% of demand at sea level, 10%–11% at 2,000 m and 8%–9% at 4,000 m. When C_aero decreased this led to better performance by making more energy available for acceleration. Accordingly, C_kin increased from 20%–24% at sea level to 23%–27% at 4,000 m. There was no effect of altitude specific to body size. Electronic Publication     

Lipid and lipoprotein profiles, cardiovascular fitness, body composition, and diet during and after resistance, aerobic and combination training in young women

The purpose of this study was to evaluate the effects of various modes of training on the time-course of changes in lipoprotein-lipid profiles in the blood, cardiovascular fitness, and body composition after 16 weeks of training and 6 weeks of detraining in young women. A group of 48 sedentary but healthy women [mean age 20.4 (SD 1) years] were matched and randomly placed into a control group (CG, n=12), an aerobic training group (ATG, n=12), a resistance training group (RTG, n=12), or a cross-training group that combined both aerobic and resistance training (XTG, n=12). The ATG, RTG and XTG trained for 16 weeks and were monitored for changes in blood concentrations of lipoprotein-lipids, cardiovascular fitness, body composition, and dietary composition throughout a 16 week period of training and 6 weeks of detraining. The ATG significantly reduced blood concentrations of triglycerides (TRI) (P < 0.05) and significantly increased blood concentrations of high-density lipoprotein-cholesterol (HDL-C) after 16 weeks of training. The correlation between percentage fat and HDL-C was 0.63 (P < 0.05), which explained 40% of the variation in HDL-C, while the correlation between maximal oxygen uptake (V˙O_2max) and HDL-C was 0.48 (P < 0.05), which explained 23% of the variation in HDL-C. The ATG increased V˙O_2max by 25% (P < 0.001) and decreased percentage body fat by 13% (P < 0.05) after 16 weeks. Each of the alterations in the ATG had disappeared after the 6 week detraining period. The concentration of total cholesterol (TC), TRI, HDL-C and low density lipoprotein-cholesterol in the blood did not change during the study in RTG, XTG and CG. The RTG increased upper and lower body strength by 29% (P < 0.001) and 38%, respectively. The 6 week detraining strength values obtained in RTG were significantly greater than those obtained at baseline. The XTG increased upper and lower body strength by 19% (P < 0.01) and 25% (P < 0.001), respectively. The 6 week detraining strength values obtained in XTG were significantly greater than those obtained at baseline. The RTG, XTG and CG did not demonstrate any significant changes in either V˙O_2max, or body composition during the training and detraining periods. The results of this study suggest that aerobic-type exercise improves lipoprotein-lipid profiles, cardiorespiratory fitness and body composition in healthy, young women, while resistance training significantly improved upper and lower body strength only. Accepted: 9 April 2000     

Relationship between smoking habits and low-density lipoprotein-cholesterol,high-density lipoprotein-cholesterol,and triglycerides in a hypercholesterolemic adult cohort,in relation to gender and age

Elevated total cholesterol, the related low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, triglycerides, and smoking habits are risk factors for cardiovascular disease. The objective of this study was to investigate the influence of habitual smoking on these parameters in 492 hypercholesterolemic men and women, aged between 26 and 66 years. Relative differences between smokers and non-smokers in the mean values of total cholesterol, low-density and high-density lipoprotein-cholesterol, and triglycerides were 2.2%, 5.5%, −8.1%, and 13.7%, respectively. These differences were statistically significant (P<0.04). Over the entire cohort, including men and women, age did not affect the mean values significantly, except for total cholesterol and triglyceride values in smoking women, which were significantly higher in women over 50 years than in the younger women (P=0.011 and P=0.004). In both men and women, regardless of smoking habits, 43%–59% of subjects exceeded the upper reference range value for low-density lipoprotein-cholesterol (4.9 mmol/l), while 38%–59% exceeded the upper reference range value for triglycerides (2.0 mmol/l) and 82%–91% had values below the lower reference range value for high-density lipoprotein-cholesterol (0.9 mmol/l for men, 1.2 mmol/l for women). Smoking habits hardly influenced the extent to which reference values were exceeded, except for low-density lipoprotein-cholesterol in all subjects (higher percentage for smokers, P=0.041). Similar results were obtained for age, except for triglycerides in smoking women, which showed high values in 26% of women <50 years versus 50% of women ≥50 years (P=0.026). In conclusion, smoking has an adverse effect on low-density and high-density lipoprotein-cholesterol, and triglycerides in a hypercholesterolemic population of men and women, regardless of age. Received: 9 November 2001 / Accepted: 4 May 2002     

Prediction and validation of total and regional skeletal muscle mass by ultrasound in Japanese adults

The present study was performed to develop regression-based prediction equations for skeletal muscle (SM) mass by ultrasound and to investigate the validity of these equations in Japanese adults. Seventy-two Japanese men (n=38) and women (n=34) aged 18–61 years participated in this study and were randomly separated into two groups: the model development group (n=48) and the validation group (n=24). The total and regional SM mass were measured using magnetic resonance imaging (MRI) 1.5 T-scanners with spin-echo sequence. Contiguous transverse images (about 150 slices) with a slice thickness of 1 cm were obtained from the first cervical vertebra to the ankle joints. The volume of SM was calculated from the summation of digitized cross-sectional area. The SM volume was converted into mass units (kg) by an assumed SM density of 1.04 kg l⁻¹. The muscle thickness (MTH) was measured by B-mode ultrasound (5 MHz scanning head) at nine sites on the anatomical SM belly. Strong correlations were observed between the site-matched SM mass (total, arm, trunk body, thigh, and lower leg) by MRI measurement and the MTH × height (in m) in the model development group (r=0.83–0.96 in men, r=0.53–0.91 in women, P<0.05). When the SM mass prediction equations were applied to the validation group, significant correlations were also observed between the MRI-measured and predicted SM mass (P<0.05). The predicted total SM mass for the validation group was 19.6 (6.5) kg and was not significantly different from the MRI-measured SM mass of 20.2 (6.5) kg. Bland–Altman analysis did not indicate a bias in prediction of the total SM mass for the validation group (r=0.00, NS). These results suggested that ultrasound-derived prediction equations are a valid method to predict SM mass and an alternative to MRI measurement in healthy Japanese adults.     

Changes in myosin heavy chain composition with heavy resistance training in 60- to 75-year-old men and women

The purpose of this investigation was to assess the myosin heavy chain (MHC) expression in the vastus lateralis muscle from elderly men and women, and to determine whether heavy resistance training influences its expression. Twenty healthy, mildly physically active subjects gave their informed consent to participate in the study. The experimental group consisted of seven men and seven women [mean (SD) age 65.5 (4.1) years] and the control group consisted of three men and three women [mean (SD) age 62.3 (3.6) years]. The 6-month resistance training program was divided into two phases with weeks 1–12 consisting of high-intensity resistance training, and weeks 13–24 involving power training. Muscle biopsy samples were taken from the vastus lateralis muscle at week 0 and week 24 using the needle biopsy technique. The male and female experimental groups both exhibited a significant decrease (P ≤ 0.05) in the percentage of MHC IIb, while the experimental female group also demonstrated a significant increase (P ≤ 0.05) in the expression of MHC IIa, after 24 weeks of heavy resistance training. There was no change in MHC expression within the control group. The male [130.4 (25.3) kg vs 171.1 (30.5) kg] and female [58.2 (8.3) kg vs 77.9 (11.1) kg] experimental groups exhibited a significant increase (P ≤ 0.05) in the maximal strength values for the 1 repetition maximum (1RM) squat exercise. The control group showed no change in strength for the 1RM squat exercise for either the male [115.8 (35.10 kg vs 123.8 (47.2) kg] or female [57.5 (99.0) kg vs 58.3 (2.9) kg] groups. The results clearly show that elderly subjects undergoing heavy resistance training have the ability to produce a similar shift in the expression of MHC isoforms from MHC IIb to MHC IIa, as has been shown to occur in younger subjects. This highlights the plasticity of human skeletal muscle in response to heavy resistance training, even at older ages. Accepted: 25 September 2000     

Group A Streptococcal Meningitis in the Antibiotic Era

 A case of group A streptococcal meningitis is reported and the 51 cases reported in the literature since 1966 reviewed. A total of 24 men and 24 women were included in the study; the mean age (±SD) was 20.9±25.5 years. Fifty-eight percent of the patients had comorbid conditions, 80% had a distant focus of infection, and 65.8% had blood cultures positive for group A streptococci. Seventy-five per cent of the patients were treated with penicillin. The overall case-fatality rate was 12% (6 patients). Sequelae were more prevalent among children (44%) than among adults (7.7%) (OR=9.43; 95% CI, 1.02–438.95;P=0.03). Group A streptococcus is a rare cause of pyogenic meningitis, affecting mainly children or adults with co-morbidity. Although the case-fatality rate is relatively low, neurological sequelae are frequent among survivors, especially children.     

Increased heart rate variability and executive performance after aerobic training in the elderly

This study examined the effects of two short physical training programs on various parameters of heart rate variability (HRV) and on executive performance in older people. Twenty-four sedentary men and women aged 65–78 years were randomly assigned to an aerobic exercise program or a stretching program three times a week for 12 weeks. Resting HRV was measured in time and frequency domains in each participant before and after the 12-week programs. Executive performance was measured with the Wisconsin card sorting test (WCST). Significant group–session interactions emerged for the standard deviation of normal beat-to-beat (R–R) intervals, the root-mean-square of successive R–R, and high frequency power. Only the aerobic training group increased vagal-mediated HRV parameters. Moreover, only the participants in the aerobic training group improved their performance on the WCST. These results highlight the role of aerobic exercise as an important cardiac and brain protective factor, and suggest a direct link between exercise, HRV, and cognition in the aged population.     

Hip bone mineral density is improved by high-impact aerobic exercise in postmenopausal women and men over 50 years

Fifteen men and women (six men) between the ages of 50 and 73 years were recruited to begin keep-fit classes. They were matched for sex, age, menopausal status and mass to 15 non-exercising controls. The keepfit classes were two to three times a week and included high-impact exercise, including step and jumping exercises specifically to load the proximal femur and spine. Proximal femur, lumbar spine and total body bone mineral density (BMD) were measured at 0 and 12 months. Urinary pyridinoline (Pyr) and deoxypyridinoline (dPyr) crosslinks were measured every 6 months to assess bone resorption. Quadriceps isometric strength was measured every 6 months. BMD increased non-significantly at the femoral neck [1.57 (0.8%] and Wards triangle [1.97 (1.4%], and significantly at the greater trochanter 2.21 (0.9)% (P=0.02) in the exercise group. Femoral neck BMD decreased by −1.9(0.8)% (P=0.049) in the control group, which was significantly different from the change in the exercise group (P=0.009). BMD did not change at the Wards triangle or trochanter in the controls. Lumbar spine BMD did not change in either group. Total body BMD did not change in the exercise group, but decreased by −0.79 (0.3)% (P=0.02) in the controls. Follwing 6 months of the exercise classes, Pyr and dPyr crosslinks were significantly reduced [−19.0 (7.2)%;P=0.0019 and −20.0 (7.7)%;P=0.021 respectively]. There was no significant change in crosslinks after 1 year, and no change at any time in the controls. Quadriceps strength changed by 5.4 (3.7)% in the exercise group and by −6.9 (2.5)% (P=0.01) in the control group after 12 months, being significant between groups (P=0.008). This study suggests that high-impact, aerobic exercise in postmenopausal women and men over 50 years old is feasible and effective at maintaining muscle strength and increasing proximal femur BMD but not spine or total body BMD.     

High-intensity endurance training improves adiponectin mRNA and plasma concentrations

Adiponectin is an anti-inflammatory protein that reduced in obesity. Exercise training may reduce the adipose tissue (AT), although it is not well known whether exercise-induced change in AT, increases the adiponectin mRNA expression and plasma concentrations or not; therefore, the purpose of this study was to investigate the adiponectin mRNA and plasma concentrations in middle-aged men after 12 weeks high-intensity exercise training and after a week detraining. Sixteen sedentary overweight and obese middle-aged men (age 41.18 ± 6.1 years; ± SD) volunteered to participate in this study. The subjects were randomly assigned to training group (n = 8) or control group (n = 8). The training group performed endurance training 4 days a week for 12 weeks at an intensity corresponding to 75–80% individual maximum oxygen consumption for 45 min. After 12 weeks of training, subjects underwent a week of detraining. The results showed that the BMI as well as central and peripheral AT volume were decreased in the training group compared to the control group (P < 0.05). After 12 weeks, the training group resulted in a significant increase (P < 0.05) in the adiponectin gene expression in abdominal and gluteal subcutaneous AT when compared with the control group. The results showed that plasma adiponectin concentrations increased and insulin resistance decreased after training compared to the control group (P < 0.05). After a week of detraining, the variables were not changed significantly in the training group. In conclusion, high-intensity endurance training caused an increase adiponectin mRNA in obese middle-aged men.     

The effect of eccentric strength training on heart rate and on its variability during isometric exercise in healthy older men

The purpose of this study was to investigate if chronic eccentric strength training (ST) affects heart rate (HR) and heart rate variability (HRV) during sub-maximal isometric voluntary contractions (SIVC). The training group (TG) (9 men, 62 ± 2) was submitted to ST (12 weeks, 2 days/week, 2–4 sets of 8–12 repetitions at 75–80% peak torque (PT). The control group (CG) (8 men, 64 ± 4) did not perform ST. The HR and the HRV (RMSSD index) were evaluated during SIVC of the knee extension (15, 30 and 40% of PT). ST increased the eccentric torque only in TG, but did not change the isometric PT and the duration of SIVC. During SIVC, the HR response pattern and the RMSSD index were similar for both groups in pre- and post-training evaluations. Although ST increased the eccentric torque in the TG, it did not generate changes in HR or HRV.     

Sural nerve facilitation of the soleus muscle H-reflex in high level gymnasts

The effect of a non-nociceptive sural nerve stimulation on the H-reflex was examined in 6 young female gymnasts and 12 control subjects. At the 70–90 ms delays investigated between conditioning and test stimulations, the sural nerve stimulation produced a facilitation that did not differ significantly between the gymnast group (6.15% of the maximal H-reflex size, H_max) and the control group (8.12% H_max). The inter-subject dispersion was significantly larger in the control group (0.30%–21.04% H_max) than in the gymnast group (4.44%–7.70% H_max). It is suggested that this narrow range of sural nerve facilitation may have resulted from the prolonged specific training of these sportswomen. Accepted: 15 March 2000     

The effect of endurance training on resting heart rate variability in sedentary adult males

Eleven previously sedentary adult males, serving as the experimental (EXP) group [mean (SE) age 36.6 (1.7) years, body mass 87.2 (4.3) kg, body mass index, BMI, 28.4 (1.5) kg·m^–2] participated in a 16-week supervised exercise program (3 days·week^–1, 30 min·day^–1, at ≅80% of heart rate reserve) to determine the temporal effects of a moderate-to-vigorous-intensity exercise program on heart rate variability (HRV). Five sedentary males [mean (SD) age 36.6 (4.2 )years, body mass 83.8 (6.6) kg, BMI 22.8 (1.7) kg·m^–2] served as non-exercising controls (CON). HRV was measured every 4 weeks from a resting electrocardiogram obtained while subjects paced their breathing at 10 breaths·min^–1 (0.167 Hz). The time-domain measures of HRV recorded were the proportion of adjacent intervals differing by more than 50 ms (pNN50), the root mean square of successive differences (rMSSD), and the standard deviation of the resting interbeat interval. The frequency-domain measures recorded were high (HF) and low (LF) frequency oscillations, as determined using the fast Fourier transform technique. Aerobic capacity (i.e., peak oxygen uptake) increased by 13.8% in EXP (P<0.001), but did not change in CON. Resting heart rate did not change in either EXP or CON. In EXP, pNN50 at week 12 (P<0.01), rMSSD at weeks 12 (P<0.01) and 16 (P=0.05), and HF power at weeks 12 (P<0.01) and 16 (P=0.05) were elevated above baseline. Time- and frequency-domain measures of HRV remained unchanged in CON. It is concluded that a moderate-to-vigorous-intensity exercise program produces increases in time- and frequency-domain measures of HRV within 12 weeks. Electronic Publication     

Effect of concurrent strength and endurance training on skeletal muscle properties and hormone concentrations in humans

The purpose of this study was to investigate the effect of concurrent strength and endurance training on strength, endurance, endocrine status and muscle fibre properties. A total of 45 male and female subjects were randomly assigned to one of four groups; strength training only (S), endurance training only (E), concurrent strength and endurance training (SE), or a control group (C). Groups S and E trained 3 days a week and the SE group trained 6 days a week for 12 weeks. Tests were made before and after 6 and 12 weeks of training. There was a similar increase in maximal oxygen consumption (V˙O_{2 max}) in both groups E and SE (P < 0.05). Leg press and knee extension one repetition maximum (1 RM) was increased in groups S and SE (P < 0.05) but the gains in knee extension 1 RM were greater for group S compared to all other groups (P < 0.05). Types I and II muscle fibre area increased after 6 and 12 weeks of strength training and after 12 weeks of combined training in type II fibres only (P < 0.05). Groups SE and E had an increase in succinate dehydrogenase activity and group E had a decrease in adenosine triphosphatase after 12 weeks of training (P < 0.05). A significant increase in capillary per fibre ratio was noted after 12 weeks of training in group SE. No changes were observed in testosterone, human growth hormone or sex hormone binding globulin concentrations for any group but there was a greater urinary cortisol concentration in the women of group SE and decrease in the men of group E after 12 weeks of training (P < 0.05). These findings would support the contention that combined strength and endurance training can suppress some of the adaptations to strength training and augment some aspects of capillarization in skeletal muscle. Accepted: 10 November 1998     

Maximal strength-training effects on force-velocity and force-power relationships explain increases in aerobic performance in humans

Maximal strength-training with an emphasis on maximal mobilization during cross-country skiing increases exercise economy when double-poling. The aim of this experiment was to investigate whether the mechanism of this increase is a change in the force-velocity relationship and the mechanical power output. A group of 19 cross-country skiers having an average peak oxygen uptake of 255 ml·kg^–0.67 body mass·min^–1 or 61 ml·kg^–1·min^–1 were randomly assigned to either a high resistance-training group (n=10) or a control group (n=9). Upper body endurance was tested on a ski ergometer. The high-resistance-training group trained for 15 min on three occasions a week for 9 weeks. Training consisted of three series of five repetitions using 85% of one repetition maximum (1RM), with emphasis on high velocity in the concentric part of the movement. Upper body exercise economy, 1RM and time to exhaustion increased significantly in the high resistance-training group, but was unchanged in the control group. Peak power and the velocities for a given load increased significantly, except for the two lowest loads. We conclude that the increased exercise economy after a period of upper body high resistance-training can be partly explained by a specific change in the force-velocity relationship and the mechanical power output. Electronic Publication     

Effect of glutamine supplementation combined with resistance training in young adults

The purpose of this study was to assess the effect of oral glutamine supplementation combined with resistance training in young adults. A group of 31 subjects, aged 18–24 years, were randomly allocated to groups (double blind) to receive either glutamine (0.9 g·kg lean tissue mass^–1·day^–1; n=17) or a placebo (0.9 g maltodextrin·kg lean tissue mass^–1·day^–1; n=14) during 6 weeks of total body resistance training. Exercises were performed for four to five sets of 6–12 repetitions at intensities ranging from 60% to 90% 1 repetition maximum (1 RM). Before and after training, measurements were taken of 1 RM squat and bench press strength, peak knee extension torque (using an isokinetic dynamometer), lean tissue mass (dual energy X-ray absorptiometry) and muscle protein degradation (urinary 3-methylhistidine by high performance liquid chromatography). Repeated measures ANOVA showed that strength, torque, lean tissue mass and 3-methylhistidine increased with training (P<0.05), with no significant difference between groups. Both groups increased their 1 RM squat by approximately 30% and 1 RM bench press by approximately 14%. The glutamine group showed increases of 6% for knee extension torque, 2% for lean tissue mass and 41% for urinary levels of 3-methylhistidine. The placebo group increased knee extension torque by 5%, lean tissue mass by 1.7% and 3-methylhistidine by 56%. We conclude that glutamine supplementation during resistance training has no significant effect on muscle performance, body composition or muscle protein degradation in young healthy adults. Electronic Publication     

Effect of high versus low-velocity resistance training on muscular fitness and functional performance in older men

This study investigated the effect of a 10-week power training (PT) program versus traditional resistance training (TRT) on functional performance, and muscular power and strength in older men. Twenty inactive volunteers (60–76 years old) were randomly assigned to a PT group (three 8–10 repetition sets performed as fast a possible at 60% of 1-RM) or a TRT group (three 8–10 repetition sets with 2–3 s contractions at 60% of 1-RM). Both groups exercised 2 days/week with the same work output. Outcomes were measured with the Rikli and Jones functional fitness test and a bench and leg press test of maximal power and strength (1-RM). Significant differences between and within groups were analyzed using a two-way analysis of variance (ANOVA). At 10 weeks there was a significantly (P < 0.05) greater improvement in measures of functional performance in the PT group. Arm curling improved by 50 versus 3% and a 30 s chair-stand improved by 43 versus 6% in the PT and TRT groups, respectively. There was also a significantly greater improvement in muscular power (P < 0.05) in the PT group. The bench press improved by 37 versus 13%, and the leg press by 31 and 8% in the PT and TRT groups, respectively. There was no significant difference between groups in improved muscular strength. It appears that in older men there may be a significantly greater improvement in functional performance and muscular power with PT versus low velocity resistance training.     

Twitch potentiation after voluntary versus electrically induced isometric contractions in human knee extensor muscles

Twitch potentiation in knee extensor (KE) muscles after a 7-s conditioning isometric maximal voluntary contraction (MVC trial), submaximal (25% MVC) voluntary contraction (SVC trial) and submaximal tetanic contraction (25% MVC) induced by percutaneous electrical stimulation at 100 Hz (PES trial) was compared in 12 men aged 19–25 years. Isometric twitch characteristics of KE muscles were measured before conditioning contraction and following 10-min recovery by supramaximal electrical stimulation of the femoral nerve. During MVC trial, twitch peak torque (Pt) potentiated (P < 0.05) immediately after the conditioning contraction with sharp decline during the first and third minute of recovery. No significant potentiation of twitch Pt was observed in SVC trial. During PES trial, twitch Pt was potentiated (P < 0.05) within 3–10 min of recovery. The time-course of isometric twitch was not significantly altered by conditioning contractions. It was concluded that twitch potentiation in the KE muscles differed markedly following the three conditioning contractions.