Sarah K. McKinley-Barnard

l-Leucine Increases Skeletal Muscle IGF-1 but Does Not Differentially Increase Akt/mTORC1 Signaling and Serum IGF-1 Compared to Ursolic Acid in Response to Resistance Exercise in Resistance-Trained Men

Objective: Ursolic acid administration following resistance exercise increases mammalian target of rapamycin complex 1 (mTORC1) activity and skeletal muscle IGF-1 concentration in murines in a manner similar to l-leucine yet remains unexamined in humans. This study examined serum and skeletal muscle insulin-like growth factor-1 (IGF-1) and Akt/mTORC1 signaling activity following ingestion of either ursolic acid or l-leucine immediately after resistance exercise. Methods: Nine resistance-trained men performed 3 lower-body resistance exercise sessions involving 4 sets of 8–10 repetitions at 75%–80% one repetition maximum (1-RM) on the angled leg press and knee extension exercises. Immediately following each session, participants orally ingested 3 g cellulose placebo (PLC), l-leucine (LEU), or ursolic acid (UA). Blood samples were obtained pre-exercise and at 0.5, 2, and 6 hours postexercise. Muscle biopsies were obtained pre-exercise and at 2 and 6 hours postexercise. Results: Plasma leucine increased in LEU at 2 hours postexercise compared to PLC (p = 0.04). Plasma ursolic acid increased in UA at 2 h and 6 hours postexercise compared to PLC and LEU (p < 0.003). No significant differences were observed for serum insulin (p = 0.98) and IGF-1 (p = 0.99) or skeletal muscle IGF-1 receptor (IGF-1R; p = 0.84), Akt (p = 0.55), mTOR (p = 0.09), and p70S6K (p = 0.98). Skeletal muscle IGF-1 was significantly increased in LEU at 2 hours postexercise (p = 0.03) and 6 hours postexercise (p = 0.04) compared to PLC and UA. Conclusion: Three grams of l-leucine and ursolic acid had no effect on Akt/mTORC1 signaling or serum insulin or IGF-1; however, l-leucine increased skeletal muscle IGF-1 concentration in resistance-trained men.

Effect of resistance exercise intensity on the expression of PGC-1α isoforms and the anabolic and catabolic signaling mediators, IGF-1 and myostatin, in human skeletal muscle

The purpose of this study was to investigate the acute messenger (mRNA) expression of the peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) isoforms, insulin-like growth factor-1Ea (IGF-1Ea), and myostatin in response to 2 resistance exercise intensities. In a uniform-balanced, crossover design, 10 participants performed 2 separate testing sessions involving a lower body resistance exercise component consisting of a lower intensity (50% of 1-repetition maximum; 1RM) protocol and a higher intensity (80% of 1RM) protocol of equal volumes. Muscle samples were obtained at before exercise, 45 min, 3 h, 24 h, and 48 h postexercise. Resistance exercise did not alter total PGC-1α mRNA expression; however, distinct responses of each PGC-1α isoform were observed. The response of each isoform was consistent between sessions, suggesting no effect of resistance exercise intensity on the complex transcriptional expression of the PGC-1α gene. IGF-1Ea mRNA expression significantly increased following the higher intensity session compared with pre-exercise and the lower intensity session. Myostatin mRNA expression was significantly reduced compared with pre-exercise values at all time points with no difference between exercise intensity. Further research is needed to determine the effects of the various isoforms of PGC-1α in human skeletal muscle on the translational level as well as their relation to the expression of IGF-1 and myostatin.

Resistance Training–Induced Elevations in Muscular Strength in Trained Men Are Maintained After 2 Weeks of Detraining and Not Differentially Affected by Whey Protein Supplementation

Abstract Hwang, PS, Andre, TL, McKinley-Barnard, SK, Morales Marroquín, FE, Gann, JJ, Song, JJ, and Willoughby, DS. Resistance training–induced elevations in muscular strength in trained men are maintained after 2 weeks of detraining and not differentially affected by whey protein supplementation. J Strength Cond Res 31(4): 869–881, 2017—Resistance training (RT) with nutritional strategies incorporating whey protein intake postexercise can stimulate muscle protein synthesis and elicit hypertrophy. The early phases of training-induced anabolic responses can be attenuated with longer-term training. It is currently unknown if short-term detraining (DT) can restore these blunted anabolic responses during a subsequent retraining (ReT) period. Twenty resistance-trained men (age 20.95 ± 1.23 years; n = 20) were randomized into one of 2 groups (PRO or CHO; 25 g) in a double-blind manner. Participants followed a 4-day per week RT program (4-week RT; 2-week DT; 4-week ReT) while consuming their respective supplement only on workout days during RT and ReT, but every day during DT. At baseline, 4 weeks after RT (post-RT), 2 weeks after DT (post–2-week DT), and after 4 weeks of ReT after DT (post-ReT), leg press strength (LPS) was assessed and rectus femoris cross-sectional area and lean mass changes were assessed by ultrasonography and dual-energy x-ray absorptiometry, respectively. A factorial 2 × 4 (group by time) analyses of variance with repeated measures were used with a probability level at ⩽0.05. LPS was elevated throughout the 10-week training study (p = 0.003) with no decrease in LPS after DT in both groups. Although not statistically significant, both groups retained lean mass after DT. A 2-week period of DT appeared to retain muscular strength in resistance-trained men. Therefore, a short-term period of DT can potentially retain lower-body strength in young resistance-trained men irrespective of supplementing with 25 g of whey protein postexercise.

The effects of creatine monohydrate supplementation on creatine transporter activity and creatine metabolism in resistance trained males

Background Oral creatine supplementation is known to provide numerous benefits, including increases in lean muscle mass, muscular strength, and enhanced performance in various athletic capacities. The creatine transporter is a transmembrane protein that mediates the entry of creatine from the circulation into the muscle cell. Little is understood about the importance of the creatine transporter in controlling the uptake and regulation of creatine within human skeletal muscle. The purpose of this study was to conduct a preliminary examination of the effects of a typical creatine monohydrate supplementation regimen on the activity of the creatine transporter at the transcriptional and translational levels in resistance-trained males.

The effects of a botanical anti-inflammatory nutritional supplement while participating in a resistance training program on indices of body composition and metabolic, cardiovascular, muscular, and hemodynamic function in obese females.

Background Botanical supplements with flavonoids possess the ability to reduce inflammatory markers such as CRP, IL-6, and TNF-a. Also, they could potentially help reduce sugarinduced weight gain and facilitate weight loss. Diafin is a non-stimulant, botanical, weight loss product created from a blend of standardized Free-B-ring flavonoids and flavans from two plant extracts isolated from the Scutellaria genus of plants and the Acacia genus of plants. Flavonoids, specifically from the Scutellaria genus, have been used previously for anti-inflammatory and cardiovascular applications, and have been suggested to inhibit eicosanoid generating enzymes such as phospholipase A2, cyclooxygenases, and lipoxygenases, while concomitantly reducing prostanoids and leukotrienes. However, the exact mechanism in which flavonoids induce an anti-inflammatory effect is unclear.

Effects of a traditionally-dosed creatine supplementation protocol and resistance training on the skeletal muscle uptake and whole-body metabolism and retention of creatine in males

Background A typical oral creatine supplementation regimen involving a 5-7 day “loading phase” of 20-25 grams/day followed by a “maintenance phase” of 5-7 grams/day is typically considered as necessary to adequately saturate skeletal muscle as a lesser dose of creatine is insufficient in doing so. This rationale also assumes that the majority, if not all, of the creatine ingested at this dosage is fully utilized by skeletal muscle as a phosphate reservoir in which to re-synthesize ATP during high-intensity, short-term exercise. The purpose of this study was simply to determine the effects of this “typical” creatine dosing strategy previously mentioned on skeletal muscle creatine uptake as well as the whole-body metabolism and retention of creatine in males while engaged in resistance training.

The potential cytoprotective influence of estradiol and fish oil supplementation on indices of exercise-induced muscle damage in females

Exercise-induced muscle damage (EIMD) occurs following unaccustomed exercise, usually involving eccentric muscle contractions. Eccentric exercise contractions may cause harsh morphological changes in the individual muscle fiber. Various interventions have been proposed to attenuate EIMD and delayed onset muscle soreness (DOMS). An intriguing proposed intervention involves 17-? estradiol (estrogen) as an anti-oxidant. Estrogen has a cyto-protective effect on the sarcolemma, which protects the muscle from oxidative-induced muscle damage known to occur with strenuous exercise. It has been theorized that estrogen has the functional capacity to act as a membrane stabilizer, Due to the supposed cytoprotective effects of estrogen, females are thought to be less predisposed to exercise-induced muscle damage than males. However, females may be more prone to muscle damage during the low estrogen point in their 28-35 day cycle (follicular phase) compared to their high estrogen point (luteal phase). Numerous treatments have been proposed to minimize muscle damage and alleviate the symptoms of DOMS, but a clear beneficial treatment has not yet been identified. Another intriguing idea is that the anti-inflammatory and anti-oxidative properties of omega-3 (n-3) fatty acids may help counteract the inflammatory state associated with muscle damage and DOMS. The omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are of interest as they are common components of fish oil supplements and have been shown to be beneficial in improving some inflammatory conditions. As a result, fish oil supplementation has been suggested to be important for cytoprotection due to its anti-oxidant potential for significantly decreasing markers of muscle damage. Therefore, fish oil supplementation may reduce oxidative stress, thereby augmenting cytoprotection throughout the course of the 28-day menstrual cycle.