Oral Contraceptive Use Impairs Muscle Gains in Young Women.

ABSTRACT: Riechman, SE and Lee, CW. Oral contraceptive use impairs muscle gains in young women. J Strength Cond Res 36(11): 3074-3080, 2022-Many active young women use oral contraceptives (OCs), yet their effects on the body composition and exercise performance have not been thoroughly studied. We examined the effects of OCs on muscle responses to a standardized resistance exercise training (RET) program. Two groups of young healthy women (18-29 years old, non-OC: n = 38, OC: n = 34) underwent 10 weeks of whole-body RET (3 days·wk -1 , 3 sets, 6-10 repetitions, at 75% of maximum strength, 13 exercises). Body composition was determined using hydrostatic weighing, and blood samples were taken before and after training to measure dehydroepiandrosterone (DHEA), DHEA sulfate (DHEAS), IGF-1, and cortisol levels. There were significant differences in lean mass gains between the groups (non-OC: 3.5 ± 0.4% vs. OC: 2.1 ± 0.5% and non-OC: 1.6 ± 0.2 kg vs. OC: 1.0 ± 0.2 kg, p < 0.05). Plasma concentrations of DHEA, DHEAS, and IGF-1 were significantly lower, and cortisol levels were higher in the OC group before and after training ( p < 0.05). In addition, there were significant differences in lean mass gains depending on the androgenicity of progestin between the non-OC and medium-high groups (non-OC: 1.6 ± 0.2 kg, Low = 1.1 ± 0.2 kg, med-high = 0.3 ± 0.5 kg, p < 0.05). Oral contraceptive use impaired lean mass gains in young women after RET and was associated with lower DHEA, DHEAS, and IGF-1 and higher cortisol. The diminished lean mass gain may be related to the effect of OCs on anabolic and catabolic hormone levels or the androgenicity of progestin that may bind to androgen receptors and inhibit its function.

Interorgan Metabolism of Amino Acids in Human Health and Disease.

Amino acids are integral for human health, influencing an array of physiological processes from gene expression to vasodilation to the immune response. In accordance with this expansive range of unique functions, the tissues of the body engage in a complex interplay of amino acid exchange and metabolism to respond to the organism's dynamic needs for a range of nitrogenous products. Interorgan amino acid metabolism is required for numerous metabolic pathways, including the synthesis of functional amino acids like arginine, glutamate, glutamine, and glycine. This physiological process requires the cooperative handling of amino acids by organs (e.g., the small intestine, skeletal muscle, kidneys, and liver), as well as the complete catabolism of nutritionally essential amino acids such as the BCAAs, with their α-ketoacids shuttled from muscle to liver. These exchanges are made possible by several mechanisms, including organ location, as well as the functional zonation of enzymes and the cell-specific expression of amino acid transporters. The cooperative handling of amino acids between the various organs does not appear to be under the control of any centralized regulation, but is instead influenced by factors such as fluctuations in nutrient availability, hormones, changes associated with development, and altered environmental factors. While the normal function of these pathways is associated with health and homeostasis, affected by physical activity, diet and body composition, dysregulation is observed in numerous disease states, including cardiovascular disease and cancer cachexia, presenting potential avenues for the manipulation of amino acid consumption as part of the therapeutic approach to these conditions in individuals.

The effects of hindlimb unloading versus dietary cholesterol and resistance training on rat skeletal muscle responses.

BACKGROUND: The loss of muscle mass and concomitantly strength, poses a serious risk to the elderly and to astronauts. Dietary cholesterol (CL), in conjunction with resistance training (RT), has been strongly associated with improvements in lean mass. The purpose of this study was to examine the effects of two opposing environments on rat skeletal muscle: (1) hindlimb unloading and (2) CL and RT. METHODS: In protocol 1, 13 male Sprague-Dawley rats were unloaded for 28 days (HU; n = 6) or served as cage controls (CC; n = 7). In protocol 2, 42 rats were assigned to 1 of 6 groups: CC (n = 7), CC + CL (n = 4), RT controls (RTC; n = 7), RTC + CL (n = 8), RT (n = 8) and RT + CL (n = 8). RT/RTC consisted of squat-like exercise. RT had weights added progressively from 80 to 410 g over 5 weeks. CL was supplemented in the chow with either 180 ppm (controls) or 1800 ppm (CL). Lower limb muscles were harvested at the end of both protocols and analyzed by Western Blotting for sterol regulatory element-binding protein-2 (SREBP-2) and low-density lipoprotein-receptor (LDL-R) and protein synthesis. RESULTS: Gastrocnemius and plantaris masses and their body mass ratios were significantly lower in the HU rats than control rats. The RT rats gained significantly less body and lean mass than the RTC groups, but the plantar flexor muscles did not show any significant differences among groups. Moreover, RT groups had significantly higher plantaris mixed muscle fractional synthesis rate (FSR) than the RTC and CC animals, with the CL groups showing greater FSR than control rats. No significant differences among groups in SREBP-2 or LDL-R were observed in either protocol. CONCLUSIONS: These studies provide evidence for a relationship between skeletal muscle and cholesterol metabolism, but the exact nature of that association remains unclear.

Cumulative Muscle Protein Synthesis and Protein Intake Requirements.

Muscle protein synthesis (MPS) fluctuates widely over the course of a day and is influenced by many factors. The time course of MPS responses to exercise and the influence of training and nutrition can only be pieced together from several different investigations and methods, many of which create unnatural experimental conditions. Measurements of cumulative MPS, the sum synthesis over an extended period, using deuterium oxide have been shown to accurately reflect muscle responses and may allow investigations of the response to exercise, total protein intake requirements, and interaction with protein timing in free-living experimental conditions; these factors have yet to be carefully integrated. Such studies could include clinical and athletic populations to integrate nutritional and exercise recommendations and help guide their revisions to optimize the skeletal muscle function that is so important to overall health.

Anabolic responses to acute and chronic resistance exercise are enhanced when combined with aquatic treadmill exercise.

Aquatic treadmill (ATM) running may simultaneously promote aerobic fitness and enhance muscle growth when combined with resistance training (RT) compared with land-treadmill (LTM) running. Therefore, we examined acute and chronic physiological responses to RT, concurrent RT-LTM, and concurrent RT-ATM. Forty-seven untrained volunteers (men: n = 23, 37 ± 11 yr, 29.6 ± 4.6 kg/m(2); women: n = 24, 38 ± 12 yr, 27.53 ± 6.4 kg/m(2)) from the general population were tested for V̇o2max, body composition, and strength before and after training. All groups performed 12 wk of RT (2 wk, 3 × 8-12 sets at 60 to approximately 80% 1-repetition maximum). The RT-LTM and RT-ATM groups also performed 12 wk of LTM or ATM training (2 wk immediately post-RT and 1 wk in isolation, 60-85% V̇o2max, 250-500 kcal/session). Additionally, 25 subjects volunteered for muscle biopsy prior to and 24 h post-acute exercise before and after training. Stable isotope labeling (70% (2)H2O, 3 ml/kg) was utilized to quantify 24 h post-exercise myofibrillar fractional synthesis rates (myoFSR). Mixed-model ANOVA revealed that RT-ATM but not RT-LTM training produced greater chronic increases in lean mass than RT alone (P < 0.05). RT-LTM training was found to elicit the greatest decreases in percent body fat (-2.79%, P < 0.05). In the untrained state, acute RT-ATM exercise elicited higher 24-h myoFSRs compared with RT (+5.68%/day, P < 0.01) and RT-LTM (+4.08%/day, P < 0.05). Concurrent RT-ATM exercise and training elicit greater skeletal muscle anabolism than RT alone or RT-LTM.

Relationship of ethnicity and CD4 Count with glucose metabolism among HIV patients on Highly-Active Antiretroviral Therapy (HAART).

BACKGROUND: HIV patients on HAART are prone to metabolic abnormalities, including insulin resistance, lipodystrophy and diabetes. This study purports to investigate the relationship of ethnicity and CD4+ T cell count attained after stable highly-active antiretroviral treatment (HAART) with glucose metabolism in hyperrtriglyceridemic HIV patients without a history of diabetes. METHODS: Demographic, anthropometric, clinical, endocrinologic, energy expenditure and metabolic measures were obtained in 199 multiethnic, healthy but hypertriglyceridemic HIV-infected patients [46% Hispanic, 17% African-American, 37% Non-Hispanic White (NHW)] on stable HAART without a history of diabetes. The relationship of glucose and insulin responses to ethnicity, CD4 strata (low (<300/cc) or moderate-to-high (≥ 300/cc)), and their interaction was determined. RESULTS: African-Americans had significantly greater impairment of glucose tolerance (P < 0.05) and HbA1c levels (P < .001) than either Hispanics or NHWs. In multivariate models, after adjusting for confounders (age, sex, HIV/HAART duration, smoking, obesity, glucose, insulin and lipids), African-Americans and Hispanics had significantly higher HbA1c and 2-hour glucose levels than NHW's. Demonstrating a significant interaction between ethnicity and CD4 count (P = 0.023), African Americans with CD4 <300/cc and Hispanics with CD4 ≥300/cc had the most impaired glucose response following oral glucose challenge. CONCLUSIONS: Among hypertriglyceridemic HIV patients on HAART, African-Americans and Hispanics are at increased risk of developing diabetes. Ethnicity also interacts with CD4+ T cell count attained on stable HAART to affect post-challenge glycemic response.

Greater gains in strength and power with intraset rest intervals in hypertrophic training.

We sought to determine if hypertrophic training with intraset rest intervals (ISRs) produced greater gains in power compared with traditional rest (TRD) hypertrophic training. Twenty-two men (age 25 ± 5 years, height 179.71 ± 5.04 cm, weight 82.1 ± 10.6 kg, 6.5 ± 4.5 years of training) matched according to baseline characteristics were assigned to 12 weeks of training using TRD or ISR. Body composition, strength (1-repetition maximum [1RM] bench and squat), and power output (60% 1RM bench and squat, and vertical jump) were assessed at baseline, 4, 8, and 12 weeks. Determination of myosin heavy chain (MHC) percentage from the vastus lateralis was performed pretraining and posttraining. Body composition was analyzed by analysis of variance, whereas performance measures and MHC were analyzed by analysis of covariance with baseline values as the covariate. Data are presented as mean ± SD changes pre to post. The ISR produced greater power output in bench (TRD 32.8 ± 53.4 W; ISR 83.0 ± 49.9 W, p = 0.020) and vertical jump (TRD 91.6 ± 59.8 W; ISR 147.7 ± 52.0 W; p = 0.036) with squat power approaching significance (TRD 204.9 ± 70.2 W; ISR 282.1 ± 104.2 W; p = 0.053) after post hoc analysis (p < 0.10). The ISR produced greater gains in bench (TRD 9.1 ± 3.7 kg; ISR 15.1 ± 8.3 kg; p = 0.010) and squat (TRD 48.5 ± 17.4 kg; ISR 63.8 ± 12.0 kg; p = 0.002) strength. Both protocols produced significant gains in lean mass with no significant differences between groups (1.6 ± 2.1 kg; p = 0.869). The MHCIIx percentage decreased (-31.0 ± 24.5%; p = 0.001), whereas the MHCIIA percentage increased (28.9 ± 28.5%; p = 0.001) with no significant differences between groups. Results indicate that hypertrophy training with ISR produces greater gains in strength and power, with similar gains in lean mass and MHC alterations as TRD. The ISR may be best used in hypertrophic training for strength and power sports.

The impact of nutrition on visual cognitive performance in the nutrition, vision, and cognition in sport study.

Introduction: The purpose of this study was to examine the influence of nutritional intake on visual perceptual-cognitive performance (VCP) in young healthy adults. Methods: Ninety-eight healthy men (n = 38) and women (n = 60) aged 18-33 years participated and maintained their usual dietary intake throughout the study. VCP was measured using the NeuroTracker™ CORE (NT) 3-Dimensional (3-D) software program (15 training sessions) over a 15-day period. Food logs and extensive lifestyle measures including body composition, cardiovascular health, sleep and exercise patterns, and general readiness to perform were collected. Mean intake from 10 food logs collected over the 15 days were analyzed using Nutribase software. Statistical analyses were performed in SPSS using repeated measures ANOVA including significant covariates when appropriate. Results: Males consumed significantly more calories, macronutrients, cholesterol, choline, and zinc and performed significantly better on VCP than the females. Participants who consumed more than 40% of kcals from carbohydrates (p = 0.038), less than 24% of kcals from protein (p = 0.009), more than 2,000 µg/day lutein/zeaxanthin or more than 1.8 mg/ day vitamin B2 performed significantly better on VCP than those who consumed less than those amounts, respectively. Discussion: VCP is an important dimension of cognitive function and in the present study is influenced by higher carbohydrate, lutein/ zeaxanthin, and vitamin B2 dietary intake while high protein consumption and the female sex negatively impacted VCP.

Nutrition, lifestyle, and cognitive performance in esport athletes.

Introduction: Electronic sports, termed esports, is a growing athletic activity in which high levels of attention and cognitive performance are required. With its increasing popularity and competitiveness, interest in strategies to improve performance have emerged. Improving esports athlete performance, namely cognitive endurance, and resilience, may lie in nutritional or lifestyle factors. The Nutrition, Vision, and Cognition in Sport Studies (IONSport) investigated nutritional and behavioral factors that can influence cognition via 3-dimensional multiple objects tracking test (3DMOT) via Neurotracker X (NTx) software. The purpose of this study was to characterize the lifestyle of high level esports athletes with detailed nutrition, sleep, and physical activity assessments, and their association to gaming related cognitive performance. Methods: 103 male and 16 elite female esports athletes aged 16 to 35 years old completed surveys, food records, and cognitive testing sessions over 10 days. Participants were instructed to maintain their normal dietary and lifestyle habits. Results: There were positive significant associations between average NTx scores and the following nutrients: magnesium, phosphorous, potassium, sodium, zinc, selenium, thiamin, niacin, vitamins B6 and B12, folate, cholesterol, saturated, polyunsaturated, and monounsaturated fats, omega-6 and omega-3 fatty acids, and choline. Majority of participants did not meet recommended dietary allowances (RDAs) for these micronutrients nor the recommended intakes for dairy, fruit, and vegetables. There was a significant (p = 0.003) positive (r = 0.272) association between total vegetable intake and average NTx score. There was a significant negative association (p = 0.015) with our final sustain session, which measured cognitive resilience, and the Stanford Sleepiness Scale score. Repeated measures analysis was done with these groups over the 18 core NTx sessions. There were significant (p = 0.018) differences between the two groups with those who consumed the recommended amount of protein or more performing significantly better on NTx over the 18 sessions than those that did not consume enough protein. Those who consumed the recommended intakes for riboflavin, phosphorous, vitamin B12, and selenium performed significantly better over the 18 core NTx sessions than those that did not meet the recommended amounts. Discussion: The need for a nutrition intervention that is rich in protein, vitamins, and minerals is warranted in this population.

The Effect of Choline and Resistance Training on Strength and Lean Mass in Older Adults.

Choline plays many important roles, including the synthesis of acetylcholine, and may affect muscle responses to exercise. We previously observed correlations between low choline intake and reduced gains in strength and lean mass following a 12-week resistance exercise training (RET) program for older adults. To further explore these findings, we conducted a randomized controlled trial. Three groups of 50-to-69-year-old healthy adults underwent a 12-week RET program (3x/week, 3 sets, 8-12 reps, 70% of maximum strength (1RM)) and submitted >48 diet logs (>4x/week for 12 weeks). Participants' diets were supplemented with 0.7 mg/kg lean/d (low, n = 13), 2.8 mg/kg lean/d (med, n = 11), or 7.5 mg/kg lean/d (high, n = 13) of choline from egg yolk and protein powder. The ANCOVA tests showed that low choline intake, compared with med or high choline intakes, resulted in significantly diminished gains in composite strength (leg press + chest press 1RM; low, 19.4 ± 8.2%; med, 46.8 ± 8.9%; high, 47.4 ± 8.1%; p = 0.034) and thigh-muscle quality (leg press 1RM/thigh lean mass; low, 12.3 ± 9.6%; med/high, 46.4 ± 7.0%; p = 0.010) after controlling for lean mass, protein, betaine, and vitamin B12. These data suggest that low choline intake may negatively affect strength gains with RET in older adults.

Regulators of blood lipids and lipoproteins? PPARδ and AMPK, induced by exercise, are correlated with lipids and lipoproteins in overweight/obese men and women.

PPARδ is a transcription factor regulating the expression of genes involved in oxidative metabolism, which may regulate blood cholesterols through transcription of oxidative and lipoprotein metabolism genes. To determine the association of skeletal muscle PPARδ content with blood lipids and lipoproteins before and following exercise, overweight and obese men (n = 9) and women (n = 7) were recruited; age, BMI, body fat percentage, and Vo(2max) were (means ± SE) 45 ± 2.5 yr, 31.9 ± 1.4 kg/m(-2), 41.1 ± 1.5%, and 26.0 ± 1.3 mLO(2)·kg(-1)·min(-1), respectively. Subjects performed 12 wk of endurance exercise training (3 sessions/wk, progressing to 500 kcal/session). To assess the acute exercise response, subjects performed a single exercise session on a treadmill (70% Vo(2max), 400 kcal energy expenditure) before and after training. Muscle and blood samples were obtained prior to any exercise and 24 h after each acute exercise session. Muscle was analyzed for protein content of PPARδ, PPARα, PGC-1α, AMPKα, and the oxidative and lipoprotein markers FAT/CD36, CPT I, COX-IV, LPL, F(1) ATPase, ABCAI, and LDL receptor. Blood was assessed for lipids and lipoproteins. Repeated-measures ANOVA revealed no influence of sex on measured outcomes. PPARδ, PGC-1α, FAT/CD36, and LPL content were enhanced following acute exercise, whereas PPARα, AMPKα, CPT I, and COX-IV content were enhanced only after exercise training. PPARδ content negatively correlated with total and LDL cholesterol concentrations primarily in the untrained condition (r ≤ -0.4946, P < 0.05), whereas AMPKα was positively correlated with HDL cholesterol concentrations regardless of exercise (r ≥ 0.5543, P < 0.05). Our findings demonstrate exercise-induced expression of skeletal muscle PPARs and their target proteins, and this expression is associated with improved blood lipids and lipoproteins in obese adults.

Myokines derived from contracting skeletal muscle suppress anabolism in MCF7 breast cancer cells by inhibiting mTOR.

There is strong evidence that physical activity has a profound protective effect against multiple types of cancer. Here, we show that this effect may be mediated by factors released from skeletal muscle during simulated exercise, in situ, which suppress canonical anabolic signaling in breast cancer. We report attenuated growth of MCF7 breast cancer cells in the presence of a rodent-derived exercise conditioned perfusate, independent of prior exercise training. This reduction was concomitant with increased levels of DEPTOR protein and reduced mTOR activity.

Safety of using the adult OMNI Resistance Exercise Scale to determine 1-RM in older men and women.

Older adults may be susceptible to injury during high-intensity resistance exercise. It has been suggested that it may be more protective to predict one-repetition maximum (1-RM) than to measure it because of the high intensity associated with 1-RM testing, but it may be necessary to measure 1-RM for functional, diagnostic, or clinical purposes. The method of using the OMNI Resistance Exercise Scale (OMNI-RES) was examined as a guide for hexagenarian adults in estimating 1-RM. 22 healthy men (M age = 64.3 yr., SD = 3.2) and 27 women (M age = 63.8 yr., SD = 2.8) volunteered. After two weeks of orientation, participants used a predetermined rating of perceived exertion to select resistance in the assessment of 1-RM and again after 12 weeks of training. At the 1-RM trials, participants were asked to report soreness or injury during or after the exercise sessions. There were no reported incidences of injury during the current investigation. The current results provide a practical method to estimate 1-RM in older adults. As such, the OMNI-RES can be used safely in a potentially at-risk population.

Predicting muscular strength using demographics, skeletal dimensions, and body composition measures.

The purpose of this study was to develop an equation to predict strength for seven common resistance training exercises using anthropometric and demographic measures. One-hundred forty-seven healthy adults (74 males, 73 females, 35 ±â€¯12 yr, 174 ±â€¯10 cm, 88 ±â€¯19 kg) volunteered to participate. Body composition values (regional/total) and body dimensions were assessed using dual-energy x-ray absorptiometry (DEXA). Subjects underwent the following maximal strength assessments: Leg Press, Chest Press, Leg Curl, Lat Pulldown, Leg Extension, Triceps Pushdown, and Biceps Curl. Multiple linear regression with stepwise removal was used to determine the best model to predict maximal strength for each exercise. Independent predictor variables identified (p < 0.05) were height (cm); weight (kg); BMI; age; sex (0 = F,1 = M); regional lean masses (LM,kg); fat mass (FM,kg); fat free mass (FFM,kg); percent fat (%BF); arm, leg, and trunk lengths (AL, LL, TL; cm); and shoulder width (SW,cm). Analyses were performed with and without regional measures to accommodate scenarios where DEXA is unavailable. All models presented were significant (p < 0.05, R 2 = 0.68-0.83), with regional models producing the greatest accuracy. Results indicate that maximal strength for individual resistance exercises can be reasonably estimated in adults.

Performance Prediction Equation for 2000 m Youth Indoor Rowing Using a 100 m Maximal Test.

BACKGROUND: The exhaustive series of tests undergone by young athletes of Olympic rowing prior to important competitions imply loads of physical stress that can ultimately impact on mood and motivation, with negative consequences for their training and performance. Thus, it is necessary to develop a tool that uses only the performance of short distances but is highly predictive, offering a time expectancy with high reliability. Such a test must use variables that are easy to collect with high practical applicability in the daily routine of coaches. OBJECTIVE: The objective of the present study was to develop a mathematical model capable of predicting 2000 m rowing performance from a maximum effort 100 m indoor rowing ergometer (IRE) test in young rowers. METHODS: The sample consisted of 12 male rowing athletes in the junior category (15.9 ± 1.0 years). A 100 m time trial was performed on the IRE, followed by a 2000 m time trial 24-h later. RESULTS: The 2000 m mathematical model to predict performance in minutes based on the maximum 100 m test demonstrated a high correlation (r = 0.734; p = 0.006), strong reliability index (ICC: 0.978; IC95%: [0.960; 0.980]; p = 0.001) and was within usable agreement limits (Bland -Altman Agreement: -0.60 to 0.60; 95% CI [-0.65; 0.67]). CONCLUSION: The mathematical model developed to predict 2000 m performance is effective and has a statistically significant reliability index while being easy to implement with low cost.

Regulation of cellular anabolism by mTOR: or how I learned to stop worrying and love translation.

The process and regulation of cellular metabolism are extremely complex and accomplished through multiple signalling pathways that operate in parallel, and often experience significant overlap in upstream and downstream a signal transduction. Despite this complexity, single pathway or even single protein activations are commonly used to extrapolate broad characterizations of cellular metabolism. Furthermore, multiple routes for peptide-chain translation initiation exist, some of which may be either exclusive or overlapping depending on the state and environment of the cell. While it may be highly impractical to account for every aspect of metabolic regulation and permutation of mRNA translation, it is important to acknowledge that investigations relating to these pathways are often incomplete and not necessarily indicative of the overall metabolic status. This becomes urgent when considering the role that cellular anabolism plays in both healthy cellular functions and the aetiology of several disease's altered metabolisms. This review describes recent advances in the understanding of cellular metabolic regulation, with specific focus given to the complexity of 'downstream' mRNA translation initiation through both mTOR-dependent and mTOR-independent signallings.

A comparison of 2H2O and phenylalanine flooding dose to investigate muscle protein synthesis with acute exercise in rats.

The primary objective of this investigation was to determine whether (2)H(2)O and phenylalanine (Phe) flooding dose methods yield comparable fractional rates of protein synthesis (FSR) in skeletal muscle following a single bout of high-intensity resistance exercise (RE). Sprague-Dawley rats were assigned by body mass to either 4-h control (CON 4 h; n = 6), 4-h resistance exercise (RE 4 h; n = 6), 24-h control (CON 24 h; n = 6), or 24-h resistance exercise (RE 24 h; n = 6). The RE groups were operantly conditioned to engage in a single bout of high-intensity, "squat-like" RE. All rats were given an intraperitoneal injection of 99.9% (2)H(2)O and provided 4.0% (2)H(2)O drinking water for either 24 (n = 12) or 4 h (n = 12) prior to receiving a flooding dose of l-[2,3,4,5,6-(3)H]Phe 16 h post-RE. Neither method detected an effect of RE on FSR in the mixed gastrocnemius, plantaris, or soleus muscle. Aside from the qualitative similarities between methods, the 4-h (2)H(2)O FSR measurements, when expressed in percent per hour, were quantitatively greater than the 24-h (2)H(2)O and Phe flooding in all muscles (P < 0.001), and the 24-h (2)H(2)O was greater than the Phe flooding dose in the mixed gastrocnemius and plantaris (P < 0.05). In contrast, the actual percentage of newly synthesized protein was significantly higher in the 24- vs. 4-h (2)H(2)O and Phe flooding dose groups (P < 0.001). These results suggest that the methodologies provide "qualitatively" similar results when a perturbation such as RE is studied. However, due to potential quantitative differences between methods, the experimental question should determine what approach should be used.

Strength tracking using the OMNI resistance exercise scale in older men and women.

Strength tracking uses ratings of perceived exertion (RPE) as a reference value to determine changes in strength as a function of a resistance training program. The purpose of this investigation was to determine if the OMNI Resistance Exercise Scale (OMNI-RES) could be used to track training-induced strength changes in older adults. Twenty-two men (64.3 + 3.2 years) and 27 women (63.8 + 2.8 years) volunteered to participate. Subjects underwent a maximal lifting test, during which they estimated perceived exertion before and following 12 weeks of resistance exercise training. Leg press (LP), latissimus dorsi pull-down (LA), chest press (CP), leg extension (LE), leg curl (LC), arm extension (AE), and arm curl (AC) were performed. Paired samples t-tests were used to compare resistance lifted pre- and post-training at each criterion RPE (4, 6, and 8). One repetition maximum increased from pretraining to post-training (p < 0.05) for all exercises. The resistance lifted at each criterion RPE also increased (p < 0.05) during the 12-week training session for every exercise. Older adults lifted more weight at 3 criterion RPEs as their strength increased, providing an RPE-based procedure to track strength training changes using the OMNI-RES. As such, it seems that RPE from the OMNI-RES can be used to track strength in older adults.

RPE at relative intensities after 12 weeks of resistance-exercise training by older adults.

The constant-RPE tracking model monitors progress over the course of exercise training. During aerobic exercise, prior work using this model has demonstrated similar relative intensities pre- and posttraining, while the absolute workload increases posttraining. However, the prediction equation associated with these changes has not been examined during resistance training. 22 men and 27 women (M age 64 yr.) participated in a 12-wk. resistance training. Orientation determined resistances associated with RPEs of 4, 5-6, 7-8, and 9 on the OMNI-Resistance Exercise Scale for each of seven exercises for each participant. Individuals trained 3 days a week for 12 wk. Linear regression was used to calculate percent of 1-repetition maximum (%1-RM) at RPE 4, 6, and 8 for the exercises. Paired sample t tests, comparing pre- and posttraining %1-RMs at each RPE, indicated that posttraining %1-RMs were higher for RPE 4 and 6 for each exercise, while at RPE 8, results were significant for only 3 exercises. Thus for at least the RPE 4 and 6, the constant RPE tracking model is appropriate for resistance exercise; however, the equation of prediction appears to differ from that for aerobic exercise. Development of a new prediction equation may be necessary to track relative strength in older adults.