Resistance exercise stress: theoretical mechanisms for growth hormone processing and release from the anterior pituitary somatotroph.

Heavy resistance exercise (HRE) is the most effective method for inducing muscular hypertrophy and stimulating anabolic hormones, including growth hormone, into the blood. In this review, we explore possible mechanisms within the GH secretory pathway of the pituitary somatotroph, which are likely to modulate the flow of hormone synthesis and packaging as it is processed prior to exocytosis. Special emphasis is placed on the secretory granule and its possible role as a signaling hub. We also review data that summarize how HRE affects the quality and quantity of the secreted hormone. Finally, these pathway mechanisms are considered in the context of heterogeneity of the somatotroph population in the anterior pituitary.

Insulin-like growth factor-I biocompartmentalization across blood, interstitial fluid and muscle, before and after 3 months of chronic resistance exercise.

This investigation examined the influence of 12-week ballistic resistance training programs on the IGF-I system in circulation, interstitial fluid, and skeletal muscle, at rest and in response to acute exercise. Seventeen college-aged subjects (11 women/6 men; 21.7 ± 3.7 yr) completed an acute ballistic exercise bout before and after the training program. Blood samples were collected pre-, mid-, and postexercise and analyzed for serum total IGF-I, free IGF-I, and IGF binding proteins (IGFBPs) 1-4. Dialysate and interstitial free IGF-I were analyzed in vastus lateralis (VL) interstitial fluid collected pre- and postexercise via microdialysis. Pre- and postexercise VL muscle biopsies were analyzed for IGF-I protein expression, IGF-I receptor phosphorylation (p-IGF-IR), and AKT phosphorylation (p-AKT). Following training, basal serum IGF-I, free IGF-I, IGFBP-2, and IGFBP-3 decreased whereas IGFBP-1 and IGFBP-4 increased. Training reduced basal dialysate and interstitial free IGF-I but had no effect on basal skeletal muscle IGF-I, p-IGF-IR, or p-AKT. Acute exercise elicited transient changes in IGF-I system concentrations and downstream anabolic signaling both pre- and posttraining; training did not affect this acute exercise response. Posttraining, acute exercise-induced changes in dialysate/interstitial free IGF-I were strongly correlated with the changes in intramuscular IGF-I expression, p-IGF-IR, and p-AKT. The divergent influence of resistance training on circulating/interstitial and skeletal muscle IGF-I demonstrates the importance of concurrent, multiple biocompartment analysis when examining the IGF-I system. As training elicited muscle hypertrophy, these findings indicate that IGF-I's anabolic effects on skeletal muscle are mediated by local, rather than systemic mechanisms.NEW & NOTEWORTHY In the first investigation to assess resistance training's effects on the IGF-I system in serum, interstitial fluid, and skeletal muscle, training decreased basal circulating and interstitial IGF-I but did not alter basal intramuscular IGF-I protein activity. Posttraining, acute exercise-induced interstitial IGF-I increases were strongly correlated with intramuscular IGF-I expression and signaling. These findings highlight the importance of multibiocompartment measurement when analyzing IGF-I and suggest that IGF-I's role in hypertrophic adaptations is locally mediated.

Exercise medicine for cancer cachexia: targeted exercise to counteract mechanisms and treatment side effects.

PURPOSE: Cancer-induced muscle wasting (i.e., cancer cachexia, CC) is a common and devastating syndrome that results in the death of more than 1 in 5 patients. Although primarily a result of elevated inflammation, there are multiple mechanisms that complement and amplify one another. Research on the use of exercise to manage CC is still limited, while exercise for CC management has been recently discouraged. Moreover, there is a lack of understanding that exercise is not a single medicine, but mode, type, dosage, and timing (exercise prescription) have distinct health outcomes. The purpose of this review was to examine the effects of these modes and subtypes to identify the most optimal form and dosage of exercise therapy specific to each underlying mechanism of CC. METHODS: The relevant literatures from MEDLINE and Scopus databases were examined. RESULTS: Exercise can counteract the most prominent mechanisms and signs of CC including muscle wasting, increased protein turnover, systemic inflammation, reduced appetite and anorexia, increased energy expenditure and fat wasting, insulin resistance, metabolic dysregulation, gut dysbiosis, hypogonadism, impaired oxidative capacity, mitochondrial dysfunction, and cancer treatments side-effects. There are different modes of exercise, and each mode has different sub-types that induce vastly diverse changes when performed over multiple sessions. Choosing suboptimal exercise modes, types, or dosages can be counterproductive and could further contribute to the mechanisms of CC without impacting muscle growth. CONCLUSION: Available evidence shows that patients with CC can safely undertake higher-intensity resistance exercise programs, and benefit from increases in body mass and muscle mass.

The Associations between Asymmetric Handgrip Strength and Chronic Disease Status in American Adults: Results from the National Health and Nutrition Examination Survey.

This study examined the associations between asymmetric handgrip strength (HGS) and multimorbidity in American adults. Secondary analyses of data from persons aged at least 40 years from the 2011-2012 and 2013-2014 waves of the National Health and Nutrition Examination Survey were conducted. A handheld dynamometer collected HGS on each hand and persons with a strength imbalance >10% between hands were classified as having asymmetric HGS. Adults with the presence of ≥2 of the following conditions had multimorbidity: cardiovascular disease, chronic obstructive pulmonary disease, chronic kidney disease, asthma, arthritis, cancer, obesity, stroke, hypertension, high cholesterol, and diabetes. Of the n = 3483 participants included, n = 2700 (77.5%) had multimorbidity. A greater proportion of adults with multimorbidity had HGS asymmetry (n = 1234 (45.7%)), compared to persons living without multimorbidity (n = 314 (40.1%); p < 0.05). Relative to individuals without asymmetry, adults with asymmetric HGS had 1.31 (95% confidence interval (CI): 1.03-1.67) greater odds for multimorbidity. Moreover, persons with HGS asymmetry had 1.22 (CI: 1.04-1.44) greater odds for accumulating morbidities. Asymmetric strength, as another indicator of diminished muscle function, is linked to chronic morbidity status. Healthcare providers should recommend healthy behaviors for reducing asymmetries to improve muscle function and mitigate morbidity risk after completing asymmetry screenings.

Dudrick Research Symposium: Expanding the boundaries of cancer care through nutrition support.

The 2020 Dudrick Research Symposium, entitled "Expanding the Boundaries of Cancer Care Through Nutritional Support," was held on March 30, at the American Society for Parenteral and Enteral Nutrition (ASPEN), Nutrition Science & Practice Conference. It was scheduled to take place in Tampa, Florida, but had to be held virtually. The Dudrick Symposium honors the many pivotal and innovative contributions made by the late Dr Stanley J. Dudrick, physician scientist, academic leader, and a founding member of ASPEN. This year, in addition to honoring his legacy, we honored his life. As the 2019 recipient of the Dudrick Research Scholar Award, Dr Pimiento chaired the symposium. The presentations focused on discussing the history, the present and future frontiers in the overlapping fields of nutrition support and cancer care. The late Dr John Daly opened the presentation with a moving tribute to Dr Dudrick's life and then spoke about the impact of nutrition support on surgical care and outcomes for cancer patients. Dr Pimiento discussed the role of nutraceuticals for cancer chemoprevention, and the level 1 clinical evidence surrounding this topic. Dr Kraemer explored the role of exercise physiology for optimal nutrient utilization and the overlap between targeted physical activity and nutrition support to obtain better outcomes on the cancer population. The symposium was closed by Dr Stephen Hursting, who discussed the impact of obesity in the soaring cancer rates and its relationship with clinical outcomes. In this article, we cover the presentations by Drs Pimiento and Kraemer.

Radiotherapy before or during androgen-deprivation therapy does not blunt the exercise-induced body composition protective effects in prostate cancer patients: A secondary analysis of two randomized controlled trials.

BACKGROUND: Androgen deprivation therapy (ADT) contributes to lean mass loss and adiposity increases in prostate cancer patients. Radiotherapy during ADT might act synergistically and further worsen body composition. Previous investigations have shown that resistance training is an effective method of preserving body composition during ADT, however, most have not accounted for direct or indirect effects of other therapies, such as radiotherapy. Therefore, the purpose of this study was to examine training adaptations of the tissue composition in patients receiving radiation therapy (RT) prior or during ADT. METHODS: Analyses were performed by combining data from two previous trials for a total of 131 prostate cancer patients who underwent a combination of resistance and aerobic exercise training (N = 70, age: 68.9 ± 6.6y, RT-before: 13%, RT-during: 14%) or usual care (N = 61, age: 67.5 ± 7.9y, RT-before: 16%, RT-during: 20%) for 3 months upon ADT onset. Whole-body lean mass (LM), fat percentage and appendicular LM were determined by dual energy x-ray absorptiometry, and lower-leg muscle area and density by peripheral computed tomography at baseline (onset of ADT) and at 3 months post-intervention. Covariates included RT prior and during the intervention, demographic characteristics, physical symptoms, and chronic conditions. RESULTS: Radiotherapy before or during the intervention did not affect body composition. Only the usual care group experienced a significant decrease in whole-body LM (-994 ± 150 g, P < 0.001) and appendicular LM (-126 ± 19 g, P < 0.001), and an increase in whole-body fat percentage (1% ± 0.1%, P < 0.001). There was no change in lower-leg muscle area or density in either group. CONCLUSION: We suggest that radiation prior to and during ADT does not interfere with the beneficial effects of exercise training on body composition in men with prostate cancer.

Resistance Training and Milk-Substitution Enhance Body Composition and Bone Health in Adolescent Girls.

Background: Increased soft-drink consumption has contributed to poor calcium intake with 90% of adolescent girls consuming less than the RDA for calcium.Purpose/objectives: The purpose of this investigation was to determine the independent and additive effects of two interventions (milk and resistance training) on nutrient adequacy, body composition, and bone health in adolescent girls.Methods: The experimental design consisted of four experimental groups of adolescent girls 14-17 years of age: (1) Milk + resistance training [MRT]; n = 15; (2) Resistance training only [RT]; n = 15; (3) Milk only [M] n = 20; (4) Control [C] n = 16. A few significant differences were observed at baseline between the groups for subject characteristics. Testing was performed pre and post-12 week training period for all groups. Milk was provided (3, 8 oz servings) for both the MRT and the M groups. The MRT group and the RT groups performed a supervised periodized resistance training program consisting of supervised one-hour exercise sessions 3 d/wk (M, W, F) for 12 wk. Baseline dietary data was collected utilizing the NUT-P-FFQ and/or a 120 item FFQ developed by the Fred Hutchinson Cancer Research Center (Seattle, Washington). Body composition was measured in the morning after an overnight fast using dual-energy X-ray absorptiometry (DXA) with a total body scanner (ProdigyTM, Lunar Corporation, Madison, WI). A whole body scan for bone density and lumbar spine scans were performed on all subjects. Maximal strength of the upper and lower body was assessed via a one-repetition maximum (1-RM) squat and bench press exercise protocols. Significance was set at P ≤ 0.05.Results: Significant differences in nutrient intakes between groups generally reflected the nutrient composition of milk with greater intakes of protein and improved nutrient adequacy for several B vitamins, vitamin A, vitamin D, calcium, magnesium, phosphorus, potassium, and zinc. Mean calcium intake was 758 and 1581 mg/d, in the non-milk and milk groups, respectively, with 100% of girls in the milk groups consuming > RDA of 1300 mg/d. There were no effects of milk on body composition or muscle performance, but resistance training had a main effect and significantly increased body mass, lean body mass, muscle strength, and muscle endurance. There was a main effect of milk and resistance training on several measures of bone mineral density (BMD). Changes in whole body BMD in the M, RT, MRT, and CON were 0.45, 0.52, 1.32, and -0.19%, respectively (P < 0.01).Conclusions: Over the course of 12 weeks the effects of 1300 mg/d of calcium in the form of fluid milk combined with a heavy resistance training program resulted in the additive effects of greater nutrient adequacy and BMD in adolescent girls. While further studies are needed, combining increased milk consumption with resistance training appears to optimize bone health in adolescent girls.

Bioactive growth hormone in humans: Controversies, complexities and concepts.

OBJECTIVE: To revisit a finding, first described in 1978, which documented existence of a pituitary growth factor that escaped detection by immunoassay, but which was active in the established rat tibia GH bioassay. METHODS: We present a narrative review of the evolution of growth hormone complexity, and its bio-detectability, from a historical perspective. RESULTS: In humans under the age of 60, physical training (i.e. aerobic endurance and resistance training) are stressors which preferentially stimulate release of bioactive GH (bGH) into the blood. Neuroanatomical studies indicate a) that nerve fibers directly innervate the human anterior pituitary and b) that hind limb muscle afferents, in both humans and rats, also modulate plasma bGH. In the pituitary gland itself, molecular variants of GH, somatotroph heterogeneity and cell plasticity all appear to play a role in regulation of this growth factor. CONCLUSION: This review considers more recent findings on this often forgotten/neglected subject. Comparison testing of a) human plasma samples, b) sub-populations of separated rat pituitary somatotrophs or c) purified human pituitary peptides by GH bioassay vs immunoassay consistently yield conflicting results.

Trunk Muscle Strength After Lumbar Spine Fusion: A 12-Month Follow-up.

OBJECTIVE: The aim of this study was to investigate changes in trunk muscle strength 12 months after lumbar spine fusion (LSF) compared to preoperative strength. METHODS: A total of 194 patients (mean±standard deviation [SD] age, 61±21 years) who underwent LSF participated in this prospective longitudinal study. Physical measurements of the participants were made before surgery and 12 months postoperatively. Isometric trunk extension and flexion strength was measured using a strain-gauge dynamometer in the standing position. Strength changes were calculated. Regression analysis was performed to explore which factors predicted strength levels at 12 months postoperatively. RESULTS: The preoperative mean±SD extension strength was 205±144 N, which increased to 258±142 N (p<0.001) at the 12-month follow-up. Flexion strength increased from 295±172 N to 364±164 N (p<0.001). The preoperative extension/flexion strength ratio was 0.75±0.38 and remained similar (0.73±0.26) at 12 months postoperatively (p=0.39). CONCLUSION: Although trunk muscle strength increased by 26% for extension and 23% for flexion at the 12-month postoperative follow-up, both values remained objectively low. In addition, flexion strength remained higher than extension strength, which indicates an imbalance between those muscle groups. Age, severe back pain, and low trunk muscle strength before surgery predicted low trunk muscle strength at 1 year after spinal fusion.

The Effects of a Korean Ginseng, GINST15, on Hypo-Pituitary-Adrenal and Oxidative Activity Induced by Intense Work Stress.

The effect of GINST15, an enzyme fermented ginseng supplement, on hormonal and inflammatory responses to physical stress in humans is unknown. The purpose of this investigation was to examine the constitutive and stress-induced effects of GINST15 supplement on hypo-pituitary-adrenal (HPA) and antioxidant activity in addition to muscle damage. Ten women (age: 38.7 ± 7.8 years; height: 163.81 ± 4.4 cm; body mass 76.0 ± 11.6 kg) and nine men (age: 41.2. ± 9.7 years; height: 177.4 ± 5.3 cm; body mass: 88.5 ± 5.0 kg) participated in a double-blinded, placebo-controlled, counterbalanced within-group study. Participants completed three 14-day treatment cycles with different doses (high: 960 mg; low: 160 mg; placebo: 0 mg) separated by a 1-week washout period. At the end of treatment, physical stress was imposed with intense resistance exercise work stress. Participants provided blood at rest and various time points after exercise (immediately [IP], 30 min [30], 60 min [60], 24 h [+24HR]). Cortisol (CORT), superoxide dismutase (SOD), total glutathione, nonspecific antioxidant activity, total antioxidant power (TAP), and creatine kinase were measured. GINST15 supplementation produced stress-inducible dose-dependent reductions in circulating cortisol and increased enzymatic and nonspecific antioxidant activity. Twenty-four hours after intense exercise, a high dose GINST15, a bioactive ginsenoside metabolite, significantly reduces muscle damage and HPA responses to physical stress in humans; these effects may result from increased antioxidant expression.

Two types of rat pituitary somatotrophs secrete growth hormone with different biological and immunological profiles.

OBJECTIVE: Two stable subpopulations of somatotrophs reside in the rat pituitary gland. We tested the hypothesis that one produced growth hormone (GH) with greater activity when tested in the tibial line bioassay (BGH) than the other, while differences in the activities between the two groups would be less dramatic when measured by immunoassay (IGH). DESIGN: A series of studies using hypophysectomized rats, hollow fibers, treatments and culture models were used to differentiate differences in Type I and Type II anterior pituitary somatotrophs in both function and production of immunoactive and bioactive growth hormone. RESULTS: We found that dense, Type II somatotrophs (>1.070g·cm-3) differed markedly in their secretion patterns of IGH vs BGH in different In vitro and in vivo tests. In culture, Type II cells secreted five times as much BGH, and three fourths as much IGH as the less dense Type I cells. Production (storage and secretion) of BGH was 7-fold greater by Type II cells whereas IGH production was identical for the two cell types. Implantation of Type II cells into hypophysectomized rats significantly increased body weight, epiphyseal cartilage thickness, and muscle weight of the recipients; in contrast, Type I cells elicited only a small increase in body weight. Type I somatotrophs isolated from rats which had been previously fasted or insulin-treated subsequently showed only small, inconsistent changes in release relative to that from cells in the unfractionated cell population. However, release of BGH from the Type II cells was markedly decreased. CONCLUSION: Both IGH and BGH should be considered in the elucidation of GH physiology.

Effects of resistance training on expression of IGF-I splice variants in younger and older men.

Insulin-like growth factor-I (IGF-I) and its splice variants Insulin-like growth factor-I isoform Ea (IGF-IEa) and mechano growth factor (MGF) may play an important role in muscular adaptations to resistance training (RT) that may be modulated by ageing. It has been suggested that IGF-I induces cellular responses via AKT8 virus oncogene cellular homolog (Akt) and Extracellular signal-regulated kinase (Erk) signalling pathways. Therefore, resistance exercise-induced changes in skeletal muscle IGF-IEa and MGF messenger ribonucleic acid (mRNA), and MGF, Erk1/2, Akt and p70S6K protein expression were investigated before and after 21 weeks of RT in younger (YM, 20-34 yrs., n = 7) and older men (OM, 51-71 yrs., n = 10). Experimental resistance exercises (RE) of 5 × 10 repetition maximum leg presses were performed pre- and post-RT. Muscle biopsies were obtained before and 48 h after REs, to study the late response to muscle loading. The muscle proteins or mRNAs of interest were not systematically influenced by the REs or RT, except for MGF mRNA expression which was increased (p < .01) following RE before RT in OM. No differences were observed between YM and OM in any variables. This study demonstrated that basal levels or RE-induced responses in skeletal muscle MGF, Erk1/2, Akt and p70S6K protein levels or IGF-IEa and MGF mRNA expression did not differ between YM and OM, nor change systematically due to RT. Thus, ageing appears not to effect expression of the present signalling molecules involved in skeletal muscle hypertrophy.

The addition of beta-hydroxy-beta-methylbutyrate and isomaltulose to whey protein improves recovery from highly demanding resistance exercise.

OBJECTIVE: This study evaluated whether a combination of whey protein (WP), calcium beta-hydroxy-beta-methylbutyrate (HMB), and carbohydrate exert additive effects on recovery from highly demanding resistance exercise. METHODS: Thirteen resistance-trained men (age: 22.6 ± 3.9 years; height: 175.3 ± 12.2 cm; weight: 86.2 ± 9.8 kg) completed a double-blinded, counterbalanced, within-group study. Subjects ingested EAS Recovery Protein (RP; EAS Sports Nutrition/Abbott Laboratories, Columbus, OH) or WP twice daily for 2 weeks prior to, during, and for 2 days following 3 consecutive days of intense resistance exercise. The workout sequence included heavy resistance exercise (day 1) and metabolic resistance exercise (days 2 and 3). The subjects performed no physical activity during day 4 (+24 hours) and day 5 (+48 hours), where recovery testing was performed. Before, during, and following the 3 workouts, treatment outcomes were evaluated using blood-based muscle damage markers and hormones, perceptual measures of muscle soreness, and countermovement jump performance. RESULTS: Creatine kinase was lower for the RP treatment on day 2 (RP: 166.9 ± 56.4 vs WP: 307.1 ± 125.2 IU · L(-1), p ≤ 0.05), day 4 (RP: 232.5 ± 67.4 vs WP: 432.6 ± 223.3 IU · L(-1), p ≤ 0.05), and day 5 (RP: 176.1 ± 38.7 vs 264.5 ± 120.9 IU · L(-1), p ≤ 0.05). Interleukin-6 was lower for the RP treatment on day 4 (RP: 1.2 ± 0.2 vs WP: 1.6 ± 0.6 pg · ml(-1), p ≤ 0.05) and day 5 (RP: 1.1 ± 0.2 vs WP: 1.6 ± 0.4 pg · ml(-1), p ≤ 0.05). Muscle soreness was lower for RP treatment on day 4 (RP: 2.0 ± 0.7 vs WP: 2.8 ± 1.1 cm, p ≤ 0.05). Vertical jump power was higher for the RP treatment on day 4 (RP: 5983.2 ± 624 vs WP 5303.9 ± 641.7 W, p ≤ 0.05) and day 5 (RP: 5792.5 ± 595.4 vs WP: 5200.4 ± 501 W, p ≤ 0.05). CONCLUSIONS: Our findings suggest that during times of intense conditioning, the recovery benefits of WP are enhanced with the addition of HMB and a slow-release carbohydrate. We observed reductions in markers of muscle damage and improved athletic performance.

Influence of HMB supplementation and resistance training on cytokine responses to resistance exercise.

PURPOSE: The purpose of this study was to determine the effects of a multinutritional supplement including amino acids, ß-hydroxy-ß-methylbutyrate (HMB), and carbohydrates on cytokine responses to resistance exercise and training. METHODS: Seventeen healthy, college-aged men were randomly assigned to a Muscle Armor™ (MA; Abbott Nutrition, Columbus, OH) or placebo supplement group and 12 weeks of resistance training. An acute resistance exercise protocol was administered at 0, 6, and 12 weeks of training. Venous blood samples at pre-, immediately post-, and 30-minutes postexercise were analyzed via bead multiplex immunoassay for 17 cytokines. RESULTS: After 12 weeks of training, the MA group exhibited decreased interferon-gamma (IFN-γ) and interleukin (IL)-10. IL-1ß differed by group at various times. Granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-6, IL-7, IL-8, IL-12p70, IL-13, IL-17, monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein-1 beta (MIP-1ß) changed over the 12-week training period but did not differ by group. CONCLUSIONS: Twelve weeks of resistance training alters the cytokine response to acute resistance exercise, and supplementation with HMB and amino acids appears to further augment this result.

The impact of an ultramarathon on hormonal and biochemical parameters in men.

OBJECTIVE: To examine circulating hormonal responses in men competing in the Western States Endurance Run (WSER, June 23 to 24, 2012): a 161-km trail run that starts in Squaw Valley, CA, and concludes in Auburn, CA. METHODS: We examined 12 men who completed the WSER. Blood samples were obtained the morning before the race, immediately postrace (IP), and 1 (D1) and 2 (D2) days after the conclusion of the WSER. The hypothalamic-pituitary-testicular (HPT) axis was assessed by measuring testosterone and luteinizing hormone (LH). We also examined sex hormone-binding globulin (SHBG) and cortisol. Biochemical and muscle damage markers were also measured. RESULTS: Relative to prerace, there were significant (P ≤ .05) decreases in testosterone, LH, and SHBG, whereas cortisol showed a significantly marked elevation at IP. Testosterone, LH, SHBG, and cortisol remained significantly different from prerace at D1. Additionally, the testosterone to cortisol (T:C) ratio, a marker of anabolism, was decreased at IP and D1. Serum total protein, albumin, and globulin significantly decreased at IP, and remained decreased at D1 and D2. Bilirubin increased significantly IP and D1, whereas alkaline phosphatase decreased at D1 and D2. Creatine kinase, myoglobin, aspartate aminotransferase, and alanine aminotransferase increased at IP, and continued to be significantly elevated at D1 and D2. CONCLUSIONS: Training for and completing the WSER produced a significant suppression in the HPT axis as seen by decreased levels of testosterone and LH. Additionally, running the WSER continued to influence endocrine function until 2 days after the race. Furthermore, the stress caused by the WSER produced severe muscle damage.

The effects of high intensity short rest resistance exercise on muscle damage markers in men and women.

Within and between sexes, universal load prescription (as assigned in extreme conditioning programs) creates extreme ranges in individual training intensities. Exercise intensity has been proposed to be the main factor determining the degree of muscle damage. Thus, the purpose of this study was to examine markers of muscle damage in resistance-trained men (n = 9) and women (n = 9) from a high intensity (HI) short rest (SR) (HI/SR) resistance exercise protocol. The HI/SR consisted of a descending pyramid scheme starting at 10 repetitions, decreasing 1 repetition per set for the back squat, bench press, and deadlift, as fast as possible. Blood was drawn pre-exercise (pre), immediately postexercise (IP), 15 minutes postexercise (+15), 60 minutes postexercise (+60), and 24 hours postexercise (+24). Women demonstrated significant increases in interleukin 6 (IL-6; IP), creatine kinase (CK; +24), myoglobin (IP, +15, +60), and a greater relative increase when compared with men (+15, +60). Men demonstrated significant increases in myoglobin (IP, +15, +60, +24), IL-6 (IP, +15), CK (IP, +60, +24), and testosterone (IP, +15). There were significant sex interactions observed in CK (IP, +60, +24) and testosterone (IP, +15, +60, +24). Women completed the protocol faster (women: 34:04 ± 9:40 minutes, men: 39:22 ± 14:43 minutes), and at a slightly higher intensity (women: 70.1 ± 3.5%, men 68.8 ± 3.1%); however, men performed significantly more work (men: 14384.6 ± 1854.5 kg, women: 8774.7 ± 1612.7 kg). Overall, women demonstrated a faster inflammatory response with increased acute damage, whereas men demonstrated a greater prolonged damage response. Therefore, strength and conditioning professionals need to be aware of the level of stress imposed on individuals when creating such volitional high intensity metabolic type workouts and allow for adequate progression and recovery from such workouts.

Effects of resistance exercise on the HPA axis response to psychological stress during short-term smoking abstinence in men.

PURPOSE: The purpose of this study was to examine the effects of resistance exercise on the hypothalamic-pituitary-adrenal axis (HPA) response to mental challenge, withdrawal symptoms, urge to smoke, and cognitive stress during 24-hour smoking abstinence. METHODS: 8 sedentary smokers (mean±SD age: 20.1±1.7y; height: 171.6±10.8cm; body mass: 70.4±12.0kg; smoking history: 2.9±0.8y) completed a 24-hour ad libitum smoking trial (SMO) followed by two 24-hour smoking abstinence trials. During abstinence trials, participants performed six whole body resistance exercises (EX) or a control condition (CON) in the morning, followed by mental challenge tasks in the afternoon. Plasma adrenocorticotropin hormone (ACTH), and salivary and serum cortisol were measured during each visit at rest (REST), and then before (PRE-EX), immediately after (IP-EX), and 30min after exercise (30-EX); and before (PRE-MC), immediately after (IP-MC), and 30min after mental challenge (30-MC). RESULTS: Resistance exercise significantly (p≤0.05) elevated plasma ACTH and serum cortisol at IP-EX during EX compared with SMO and CON trials. Resting ACTH, salivary and serum cortisol concentrations at Pre-MC did not differ between EX and CON trials. The HPA axis response to mental challenge was similar after EX and CON trials. Finally, resistance exercise did not reduce withdrawal symptoms, urge to smoke, or stress. CONCLUSION: Resistance exercise did not substantially alter resting HPA hormones or the HPA response to mental challenge tasks during 24h of smoking abstinence.

Reproducibility of ambulatory blood pressure changes from the initial values on two different days

OBJECTIVE: We tested the reproducibility of changes in the ambulatory blood pressure (BP) from the initial values, an indicator of BP reactivity and cardiovascular health outcomes, in young, healthy adults. METHOD: The subjects wore an ambulatory BP monitor attached by the same investigator at the same time of day until the next morning on two different days (day 1 and day 2) separated by a week. We compared the ambulatory BP change from the initial values at hourly intervals over 24 waking and sleeping hours on days 1 and 2 using linear regression and repeated measures analysis of covariance. RESULTS: The subjects comprised 88 men and 57 women (mean age±SE 22.4±0.3 years) with normal BP (118.3±0.9/69.7±0.6 mmHg). For the total sample, the correlation between the ambulatory BP change on day 1 vs. day 2 over 24, waking, and sleeping hours ranged from 0.37-0.61; among women, the correlation was 0.38-0.71, and among men, it was 0.24-0.52. Among women, the ambulatory systolic/diastolic BP change was greater by 3.1±1.0/2.4±0.8 mmHg over 24 hours and by 3.0±1.1/2.4±0.8 mmHg over waking hours on day 1 than on day 2. The diastolic ambulatory BP change during sleeping hours was greater by 2.2±0.9 mmHg on day 1 than on day 2, but the systolic ambulatory BP change during sleeping hours on days 1 and 2 did not differ. Among men, the ambulatory BP change on days 1 and 2 did not differ. CONCLUSION: Our primary findings were that the ambulatory BP change from the initial values was moderately reproducible; however, it was more reproducible in men than in women. These results suggest that women, but not men, may experience an alerting reaction to initially wearing the ambulatory BP monitor. .

Dietary carbohydrate restriction improves insulin sensitivity, blood pressure, microvascular function, and cellular adhesion markers in individuals taking statins.

Statins positively impact plasma low-density lipoprotein cholesterol, inflammation and vascular endothelial function (VEF). Carbohydrate restricted diets (CRD) improve atherogenic dyslipidemia, and similar to statins, have been shown to favorably affect markers of inflammation and VEF. No studies have examined whether a CRD provides additional benefit beyond that achieved by habitual statin use. We hypothesized that a CRD (<50 g carbohydrate/d) for 6 weeks would improve lipid profiles and insulin sensitivity, reduce blood pressure, decrease cellular adhesion and inflammatory biomarkers, and augment VEF (flow-mediated dilation and forearm blood flow) in statin users. Participants (n = 21; 59.3 ± 9.3 y, 29.5 ± 3.0 kg/m(2)) decreased total caloric intake by approximately 415 kcal at 6 weeks (P < .001). Daily nutrient intakes at baseline (46/36/17% carb/fat/pro) and averaged across the intervention (11/58/28% carb/fat/pro) demonstrated dietary compliance, with carbohydrate intake at baseline nearly 5-fold greater than during the intervention (P < .001). Compared to baseline, both systolic and diastolic blood pressure decreased after 3 and 6 weeks (P < .01). Peak forearm blood flow, but not flow-mediated dilation, increased at week 6 compared to baseline and week 3 (P ≤ .03). Serum triglyceride, insulin, soluble E-Selectin and intracellular adhesion molecule-1 decreased (P < .01) from baseline at week 3, and this effect was maintained at week 6. In conclusion, these findings demonstrate that individuals undergoing statin therapy experience additional improvements in metabolic and vascular health from a 6 weeks CRD as evidenced by increased insulin sensitivity and resistance vessel endothelial function, and decreased blood pressure, triglycerides, and adhesion molecules.

Resistance exercise induces region-specific adaptations in anterior pituitary gland structure and function in rats.

The anterior pituitary gland (AP) increases growth hormone (GH) secretion in response to resistance exercise (RE), but the nature of AP adaptations to RE is unknown. To that end, we examined the effects of RE on regional AP somatotroph GH release, structure, and relative quantity. Thirty-six Sprague-Dawley rats were assigned to one of four groups: 1) no training or acute exercise (NT-NEX); 2) no training with acute exercise (NT-EX); 3) resistance training without acute exercise (RT-NEX); 4) resistance training with acute exercise (RT-EX). RE incorporated 10, 1 m-weighted ladder climbs at an 85° angle. RT groups trained 3 days/wk for 7 wk, progressively. After death, trunk blood was collected, and each AP was divided into quadrants (ventral-dorsal and left-right). We measured: 1) trunk plasma GH; 2) somatotroph GH release; 3) somatotroph size; 4) somatotroph secretory content; and 5) percent of AP cells identified as somatotrophs. Trunk GH differed by group (NT-NEX, 8.9 ± 2.4 µg/l; RT-NEX, 9.2 ± 3.5 µg/l; NT-EX, 15.6 ± 3.4 µg/l; RT-EX, 23.4 ± 4.6 µg/l). RT-EX demonstrated greater somatotroph GH release than all other groups, predominantly in ventral regions (P < 0.05-0.10). Ventral somatotrophs were larger in NT-EX and RT-NEX compared with RT-EX (P < 0.05-0.10). RT-NEX exhibited significantly greater secretory granule content than all other groups but in the ventral-right region only (P < 0.05-0.10). Our findings indicate reproducible patterns of spatially distinct, functionally different somatotroph subpopulations in the rat pituitary gland. RE training appears to induce dynamic adaptations in somatotroph structure and function.