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Background: The anterior cruciate ligament (ACL) is one of four major ligaments in the knee that provide stability during physical activity. A tear in the ACL is characterized by joint instability that leads to decreased activity, knee dysfunction, reduced quality of life and a loss of muscle mass and strength. While rehabilitation is the standard-of-care for return to daily function, additional surgical reconstruction can provide individuals with an opportunity to return to sports and strenuous physical activity. Over 200,000 ACL reconstructions are performed in the United States each year, and rehabilitation following surgery is slow and expensive. One possible method to improve the recovery process is the use of intramuscular testosterone, which has been shown to increase muscle mass and strength independent of exercise. With short-term use of supraphysiologic doses of testosterone, we hope to reduce loss of muscle mass and strength and minimize loss of physical function following ACL reconstruction compared to standard-of-care alone., Methods/design: This study is a double-blinded randomized control trial. Men 18-50 years of age, scheduled for ACL reconstruction are randomized into two groups. Participants randomized to the testosterone group receive intramuscular testosterone administration once per week for 8 weeks starting 2 weeks prior to surgery. Participants randomized to the control group receive a saline placebo intramuscularly instead of testosterone. Lean mass, muscle strength and physical function are measured at 5 time points: 2 weeks pre-surgery, 1 day pre-surgery, and 6, 12, 24 weeks post-surgery. Both groups follow standard-of-care rehabilitation protocol., Discussion: We believe that testosterone therapy will help reduce the loss of muscle mass and strength experienced after ACL injury and reconstruction. Hopefully this will provide a way to shorten the rehabilitation necessary following ACL reconstruction. If successful, testosterone therapy may also be used for other injuries involving trauma and muscle atrophy., Trial Registration: NCT01595581, REGISTRATION: May 8, 2012.

Background: In the HORMA (Hormonal Regulators of Muscle and Metabolism in Aging) Trial, supplemental testosterone and recombinant human growth hormone (rhGH) enhanced lean body mass, appendicular skeletal muscle mass, muscle performance, and physical function, but there was substantial interindividual variability in outcomes., Methods: One hundred and twelve men aged 65-90 years received testosterone gel (5 g/d vs 10 g/d via Leydig cell clamp) and rhGH (0 vs 3 vs 5 μg/kg/d) in a double-masked 2 × 3 factorial design for 16 weeks. Outcomes included lean tissue mass by dual energy x-ray absorptiometry, one-repetition maximum strength, Margaria stair power, and activity questionnaires. We used pathway analysis to determine the relationship between changes in hormone levels, muscle mass, strength, and function., Results: Increases in total testosterone of 1046 ng/dL (95% confidence interval = 1040-1051) and 898 ng/dL (95% confidence interval = 892-904) were necessary to achieve median increases in lean body mass of 1.5 kg and appendicular skeletal muscle mass of 0.8 kg, respectively, which were required to significantly enhance one-repetition maximum strength (≥ 30%). Co-treatment with rhGH lowered the testosterone levels (quantified using liquid chromatography-tandem mass spectrometry) necessary to reach these lean mass thresholds. Changes in one-repetition maximum strength were associated with increases in stair climbing power (r = .26, p = .01). Pathway analysis supported the model that changes in testosterone and insulin-like growth factor 1 levels are related to changes in lean body mass needed to enhance muscle performance and physical function. Testosterone's effects on physical activity were mediated through a different pathway because testosterone directly affected Physical Activity Score of the Elderly., Conclusions: To enhance muscle strength and physical function, threshold improvements in lean body mass and appendicular skeletal muscle mass are necessary and these can be achieved by targeting changes in testosterone levels. rhGH augments the effects of testosterone. To maximize functional improvements, the doses of anabolic hormones should be titrated to achieve target blood levels.

Context: Biomarkers that predict musculoskeletal response to anabolic therapies should expedite drug development. During collagen synthesis in soft lean tissue, N-terminal propeptide of type III procollagen (P3NP) is released into circulation. We investigated P3NP as a biomarker of lean body mass (LBM) and muscle strength gains in response to testosterone and GH., Design: Community-dwelling older men received GnRH agonist plus 5 or 10 g testosterone gel plus 0, 3, or 5 microg recombinant human GH daily. P3NP levels were measured at baseline and wk 4, 8, 12, and 16. LBM and appendicular skeletal muscle mass (ASM) were measured by dual-energy x-ray absorptiometry., Results: One hundred twelve men completed treatment; 106 underwent serum P3NP measurements. P3NP levels were higher at wk 4 than baseline (6.61 +/- 2.14 vs. 4.51 +/- 1.05, P < 0.0001) and reached plateau by wk 4 in men receiving testosterone alone. However, wk 8 P3NP levels were higher than wk 4 levels in men receiving testosterone plus recombinant human GH. Increases in P3NP from baseline to wk 4 and 16 were significantly associated with gains in LBM (r = 0.26, P = 0.007; r = 0.53, P < 0.001) and ASM (r = 0.17, P = 0.07; r = 0.40, P < 0.0001). Importantly, for participants receiving only testosterone, P3NP increases at wk 4 and 16 were related to muscle strength gains (r = 0.20, P = 0.056 and r = 0.36, P = 0.04). In stepwise regression, change in P3NP explained 28 and 30% of the change in ASM and LBM, respectively, whereas change in testosterone but not IGF-I and age provided only small improvements in the models., Conclusion: Early changes in serum P3NP levels are associated with subsequent changes in LBM and ASM during testosterone and GH administration. Serum P3NP may be a useful early predictive biomarker of anabolic response to GH and testosterone.

Background: Maximal voluntary muscle strength (MVMS) and leg power are important measures of physical function in older adults. We hypothesized that performing these measures twice within 7-10 days would demonstrate a >5% increase due to learning and familiarization of the testing procedures., Methods: Data were collected from three studies in older adult men (60-87 years) and were divided into two cohorts defined by study site and type of exercise equipment. MVMS was assessed in 116 participants using the one-repetition maximum method at two separate study visits for the chest press, latissimus pull-down, leg press, leg flexion, and leg extension exercises along with unilateral leg extension power., Results: Test-retest scores were not different and did not exceed 0.8 +/- 9.0% in Cohort 1 or 2.3 +/- 9.8% in Cohort 2, except for leg extension, which improved by 6.6 +/- 14.4% (p <.009) and 3.4 +/- 6.8% (p <.016), respectively. Repeat tests were closely correlated with initial tests (all p <.001). Pearson correlation coefficients ranged from 0.74 for leg extension power to 0.96 for leg press. Coefficients of variation were <10% (4.2%-9.0%) for all exercises except for leg extension power, which was 15.5%., Conclusions: Our findings demonstrated that test-retest measures of MVMS and power in older adult men do not differ by more than 2.3% except for leg extension, and have relatively low coefficients of variation using data collected from three studies. Moreover, these findings were similar between two study sites using different equipment, which further supports the reliability of MVMS and power testing in older adult men.

Objectives: Resistance training (RT) is a promising strategy to slow or prevent fluid cognitive decline during aging. However, the effects of strength-specific RT programs have received little attention. The purpose of this single-group proof of concept clinical trial was to determine whether a 12-week strength training (ST) program could improve fluid cognition in healthy older adults 60 to 80 years of age, and to explore concomitant physiological and psychological changes. Methods: Twenty participants (69.1 ± 5.8 years, 14 women) completed this study with no drop-outs or severe adverse events. Baseline assessments were completed before an initial 12-week control period, then participants were re-tested at pre-intervention and after the 12-week ST intervention. The NIH Toolbox Cognition Battery and standard physical and psychological measures were administered at all three time points. During the 36 sessions of periodized ST (3 sessions per week), participants were supervised by an exercise specialist and challenged via autoregulatory load progression. Results: Test-retest reliability over the control period was good for fluid cognition and excellent for crystallized cognition. Fluid composite scores significantly increased from pre- to post-intervention (8.2 ± 6.1%, p < 0.01, d = 1.27), while crystallized composite scores did not (-0.5 ± 2.8%, p = 0.46, d = -0.34). Performance on individual fluid instruments, including executive function, attention, working memory, and processing speed, also significantly improved. Surprisingly, changes in fluid composite scores had small negative correlations with changes in muscular strength and sleep quality, but a small positive correlation with changes in muscular power. Conclusions: Thus, improvements in fluid cognition can be safely achieved in older adults using a 12-week high-intensity ST program, but further controlled studies are needed to confirm these findings. Furthermore, the relationship with other widespread physiological and psychological benefits remains unclear. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the impact of muscular strength on CrossFit® workout performance. Seventeen trained men (mean ± SD age: 29.5 ± 5.6 yrs) completed three standardized CrossFit® workouts for time (Workout #1: 224.1 ± 43.3 sec; Workout #2: 155.7 ± 42.0 sec; Workout #3: 821.8 ± 49.4 sec) and 1-repetition maximum strength was measured for the following: (a) back squat (163.3 ± 23.1 kg); (b) strict shoulder press (77.5 ± 9.3 kg); and (c) deadlift (191.5 ± 24.6 kg). Total body strength (432.2 ± 49.4 kg) was calculated as the sum of all three lifts. Pearson's r correlations were used to measure the strength of the association between the strength variables and the workout performance. Significant relationships were tested with stepwise linear regression. Total body strength explained 62.5% of the variance for workout #2 (30 clean and jerks), while no significant correlations were found for workouts #1 (3 rounds of 21-15-9 repetitions of thrusters and pullups) and #3. Total body strength is a significant predictor of CrossFit® performance, specifically with workouts that include Olympic Weightlifting. [ABSTRACT FROM AUTHOR]

Patients who have undergone unicompartmental knee arthroplasty (UKA) have been reported to exhibit altered gait 19-25 months post-surgery. The most common gait impairment in this population is inadequate knee flexion and a corresponding decrease in the knee extensor moment during loading response (i.e., quadriceps avoidance). The purpose of this case series was to determine whether incorporation of antigravity treadmill training into a standard physical therapy program can eliminate quadriceps avoidance gait during the early rehabilitation phase following UKA. Four females who underwent UKA were recruited for this study. Participants completed antigravity treadmill training three times per week for 12 weeks in addition to their standard physical therapy program. Instrumented gait analysis was performed at baseline (pre-intervention), week 6 (mid-intervention), and week 12 (post-intervention). We found that peak knee flexion and the peak knee extensor moment during the weight acceptance phase of gait increased to normal values following the 12-week intervention period (14.1 ± 6.5° to 20.6 ± 1.5° and 0.4 ± 0.3 to 0.7 ± 0.2 Nm/kg respectively). The findings of this case series suggest that a standard physical therapy program that incorporates early gait training using an antigravity treadmill may be beneficial in eliminating "quadriceps avoidance" during the early rehabilitation phase following UKA. [ABSTRACT FROM AUTHOR]

The article discusses several research studies which have examined whether acute post-resistance exercise increases in testosterone, growth hormone and insulinlike growth factor 1 (IGF-1) are necessary to stimulate skeletal muscle anabolism and hypertrophy and have reached different conclusions. In the article the authors offer their opinions on the research and on the role that hormones play in resistance training.

The article reports on research conducted to investigate the influence rest interval length during exercise had on acute testosterone and cortisol responses to volume-load-equated total body hypertrophic and strength protocols in young men who performed resistance exercises. Researchers evaluated six men. They found that using short rest intervals between exercises augmented the acute total testosterone response to hypertrophic and strength protocols and that protocols did not increase cortisol.

The article reports on research conducted to compare myostatin gene expression in postmenopausal women who were and were not taking hormone therapy after eccentric exercise. Researchers evaluated 14 women. They found that postmenopausal women using hormone therapy express greater myostatin related gene expression and that women using hormone therapy experienced a greater myostatin related response to maximal eccentric exercise.

We sought to determine the effects of age and chronic exercise on muscle power in older males. We examined 32 older males 60-74 years of age and grouped as sedentary (CON, n = 11), chronic endurance trained (ET, n = 10), and chronic endurance trained + resistance training (ET + RT, n = 11). Exercise history was obtained by questionnaire. Absolute strength and power measures were obtained by the one-repetition maximum method. Relative strength and power were determined by dividing the absolute measure by the muscle mass involved in the exercise. Total and regional muscle mass was measured by DXA. Absolute and relative leg power were not significantly different among the 3 groups. In contrast, absolute leg press strength was greater in ET + RT compared with CON, and relative leg press strength was greater in ET and ET + RT compared with CON. Chronic running combined with resistance training may therefore enhance absolute and relative muscle strength in older adults, but does not influence muscle power. Endurance exercise may inhibit the ability of resistance exercise to positively influence skeletal muscle power. [ABSTRACT FROM AUTHOR]

Investigates the effects of the anabolic androgen, oxandrolone, on lean body mass (LBM), muscle size, fat and maximum voluntary muscle strength in older men. Determination of the durability of the effects after treatment was stopped; Reduction of whole body and trunk adiposity by oxandrolone.

DAVIS, J. N., L. E. GYLLENHAMMER, A. A. VANNI, M. MEIJA, A. TUNG, E. T. SCHROEDER, D. SPRUIJT-METZ, and M. I. GORAN. Startup Circuit Training Program Reduces Metabolic Risk in Latino Adolescents. Med. Sci. Sports Exerc., Vol. 43, No. 11, pp. 2195-2203, 2011. Purpose: This study aimed to test the effects of a circuit training (CT; aerobic + strength training) program, with and without motivational interviewing (MI) behavioral therapy, on reducing adiposity and type 2 diabetes risk factors in Latina teenagers. Methods: Thirty-eight Latina adolescents (15.8 ± 1.1 yr) who are overweight/obese were randomly assigned to control (C; n = 12), CT (n = 14), or CT + MI (n = 12). The CT classes were held twice a week (60-90 min) for 16 wk. The CT + Ml group also received individual or group MI sessions every other week. The following were measured before and after intervention: strength by one-repetition maximum; cardiorespiratory fitness (&Vdot;O[sub 2max]) by submaximal treadmill test; physical activity by accelerometry; dietary intake by records; height, weight, waist circumference; total body composition by dual-energy x-ray absorptiometry; visceral adipose tissue, subcutaneous adipose tissue, and hepatic fat fraction by magnetic resonance imaging; and glucose/insulin indices by fasting blood draw. Across-intervention group effects were tested using repeated-measures ANOVA with post hoc pairwise comparisons. Results: CT and CT + MI participants, compared with controls, significantly increased fitness (+16% and +15% vs -6%, P = 0.03) and leg press (+40% vs +20%, P = 0.007). Compared with controls. CT participants also decreased waist circumference (-3% vs +3%; P < 0.001), subcutaneous adipose tissue (-10% vs 8%, P = 0.04), visceral adipose tissue (-10% vs+6%, P = 0.05), fasting insulin (-24% vs+6%, P = 0.03), and insulin resistance (-21% vs -4%, P -- 0.05). Conclusions: CT may be an effective starter program to reduce fat depots and improve insulin resistance in Latino youth who are overweight/obese, whereas the additional MI therapy showed no additive effect on these health outcomes. Key Words: VISCERAL FAT, CIRCUIT TRAINING INTERVENTION, OVERWEIGHT LATINA ADOLESCENTS, FASTING INSULIN AND INSULIN RESISTANCE, MOTIVATIONAL INTERVIEWING [ABSTRACT FROM AUTHOR]