LGD-4033 and MK-677 use impacts body composition, circulating biomarkers, and skeletal muscle androgenic hormone and receptor content: A case report.

NEW FINDINGS: What is the main observation in this case? Co-administration of LGD-4033 and MK-677 increased body mass, lean mass and fat mass, while negatively impacting bone, serum lipids, liver enzymes, testosterone (total and free) and, probably, follicle-stimulating hormone. What insights does it reveal? Our cross-sectional data imply that these compounds might alter intramuscular androgenic hormone and receptor concentrations along with promoting muscular strength, when compared with previously published data from trained males. ABSTRACT: LGD-4033, a selective androgen receptor modulator, and MK-677, a growth hormone secretagogue, are being used increasingly amongst recreationally active demographics. However, limited data exist describing their effects on health- and androgen-related biomarkers. The purpose of this case study was to determine changes in body composition and biomarkers during and after continued co-administration of LGD-4033 and MK-677. We also aimed to examine muscular strength and intramuscular androgen-associated biomarkers relative to non-users. A 25-year-old male ingested LGD-4033 (10 mg) and MK-677 (15 mg) daily for 5 weeks. Blood and body composition metrics were obtained pre-, on- and post-cycle. One-repetition maximum leg and bench press, in addition to intramuscular androgens and androgen receptor content, were analysed on-cycle. We observed pre- to on-cycle changes in body composition (body mass, +6.0%; total lean body mass, +3.1%; trunk lean body mass, +6.6%; appendicular lean body mass, +4.3%; total fat mass, +15.4%; trunk fat mass, +2.8%; and appendicular fat mass, +14.8%), bone (bone mineral content, -3.60%; area, -1.1%; and bone mineral density, -2.1%), serum lipid-associated biomarkers (cholesterol, +14.8%; triglycerides, +39.2%; low-density lipoprotein-cholesterol, +40.0%; and high-density lipoprotein-cholesterol, -36.4%), liver-associated biomarkers (aspartate aminotransferase, +95.8%; and alanine aminotransferase, +205.0%) and androgen-associated biomarkers (free testosterone, -85.7%; total testosterone, -62.3%; and sex hormone-binding globulin, -79.6%); however, all variables returned to pre-cycle values post-cycle, apart from total fat mass, appendicular fat mass, bone area, total cholesterol and low-density lipoprotein-cholesterol. Follicle-stimulating hormone was below clinical reference values on- (1.2 IU/L) and post-cycle (1.3 IU/L). Intramuscular androgen receptor (-44.6%), testosterone (+47.8%) and dihydrotestosterone (+34.4%), in addition to one-repetition maximum leg press and bench press (+39.2 and +32.0%, respectively), were different in the case subject compared with non-users. These data demonstrate that LGD-4033 and MK-677 increase several body composition parameters, whilst negatively impacting bone and several serum biomarkers. Given the sparsity of data in recreationally using demographics, further research is warranted to elucidate the acute and chronic physiological effects of these anabolic agents.

The skeletal muscle microbiopsy method in exercise and sports science research: A narrative and methodological review.

BACKGROUND: The skeletal muscle microbiopsy protocol was introduced to the Exercise and Sports Science (ESS) research field in 1999 and has been used as a protocol to directly examine muscular structural and biochemical changes. There is much variation in the reporting of the microbiopsy protocol and its related pre- and post-procedure for participant care and sample collection. The purpose of this narrative and methodological review is to compare the microbiopsy to the traditional Bergström protocol used in the ESS field, identify and summarize all related microbiopsy protocols used in previous ESS studies and determine the most frequently used microbiopsy protocols aspects and associated pre- and post-biopsy procedures. METHODS: A review of literature up to January 2022 was used following the PRISMA and Cochrane Methodological Review Guide to determine frequently used methods that may facilitate optimal and potential recommendations for muscle microbiopsy needle gauge (G), concentration or dose (% or ml) and administration of local anesthetic, co-axial/cannula introducer gauge (G), muscle depth (cm), muscle sample size collected (mg), passes to collect samples, time points of muscle sampling, and promotion of participant compliance and minimization of adverse events. RESULTS: Eighty-five articles were selected based on the inclusionary requirements related to the ESS field or methodological considerations. The most frequently reported aspects in previous research to suggest the location of the vastus lateralis is the midpoint between the patella and the greater trochanter of the femur or 1/3 or 2/3 the distance from the patella to anterior superior iliac spine, 14 G biopsy needle, subcutaneous injected lidocaine administration (2 ml, 1%), 13 G co-axial/cannula, 1-2 cm muscle depth, 10-20 mg of muscle sample, ~3-time points, and 2-3 passes. DISCUSSION: There is much variation in the reporting of the microbiopsy protocol and its related pre- and post-biopsy procedures. Standardization in reporting may promote recommendations to optimize data integrity, participant safety, participant adherence to the study design, and increase reproducibility. Recommendations are made for the microbiopsy procedure based on frequently reported characteristics.

Resistance Exercise-Induced Increases in Muscle Myostatin mRNA and Protein Expression Are Subsequently Decreased in Circulation in the Presence of Increased Levels of the Extracellular Matrix Stabilizing Protein Decorin.

Resistance exercise (RE) activates cell signaling pathways associated with myostatin. Decorin is located in the extracellular matrix (ECM) and can block the inhibitory effect of myostatin. This study sought to determine the impact of low-load (LL) and high-load (HL) RE on myostatin mRNA and protein expression along with changes in muscle decorin and circulating follistatin. Ten resistance-trained men performed a LL (50% 1RM) and HL (80% 1RM) RE session using the angled leg press and leg extension with load and volume equated. Venous blood samples and muscle biopsies were obtained prior to and at 3h and 24h following each RE session. Muscle myostatin mRNA expression was increased at 24h post-exercise (p = 0.032) in LL and at 3h (p = 0.044) and 24h (p = 0.003) post-exercise in HL. Muscle decorin was increased at 24h post-exercise (p < 0.001) in LL and HL; however, muscle myostatin was increased at 24h post-exercise (p < 0.001) only in HL. For muscle Smad 2/3, no significant differences were observed (p > 0.05). Serum follistatin was increased and myostatin decreased at 24h post-exercise (p < 0.001) in LL and HL. Muscle myostatin gene and protein expression increased in response to HL RE. However, serum myostatin was decreased in the presence of increases in decorin in muscle and follistatin in circulation. Therefore, our data suggest a possible mechanism may exist where decorin within the ECM is able to bind to, and decrease, myostatin that might otherwise enter the circulation for activin IIB (ACTIIB) receptor binding and subsequent canonical signaling through Smad 2/3.

Comparison of skeletal muscle ultrastructural changes between normal and blood flow-restricted resistance exercise: A case report.

NEW FINDINGS: What is the main observation in this case? The main observation of this case report is that blood flow-restricted exercise can cause myofibrils to have an aberrant wave-like appearance that is accompanied by irregular pockets of sarcoplasm in the intermyofibrillar space, while traditional forms of damage to the Z-discs and contractile elements are not as apparent. What insights does it reveal? Our findings indicate that blood flow restriction-mediated fluid pooling might cause alterations in skeletal muscle ultrastructure after exercise that might be directly related to myofibre swelling. ABSTRACT: The acute effects of blood flow-restricted (BFR) exercise training on skeletal muscle ultrastructure are poorly understood owing to inconsistent findings and the use of largely imprecise systemic markers for indications of muscle damage. The purpose of this study was to compare myofibrillar ultrastructure before and 30 min after normal and BFR resistance exercise using transmission electron microscopy in a single individual to evaluate the feasibility of this more nuanced approach. One apparently healthy male with 13 years of resistance exercise completed six sets of both BFR [30% of one-repetition maximum (1-RM)] and normal non-occluded (70% of 1-RM) unilateral angled leg press on the contralateral leg, as a control, after assessment of 1-RM 72 h before. Vastus lateralis muscle biopsies were collected before and 30 min after each exercise session. The lengths and widths of 250 sarcomeres and the sarcoplasmic area were assessed via 20 individual transmission electron photomicrographs. Analysis revealed that BFR training (1.769 ± 0.12 µm) increased sarcomere length when compared with normal exercise (1.64 ± 0.17 µm; P < 0.001), without differences in sarcomere width between conditions (BFR, 0.90 ± 0.26 µm; normal, 0.93 ± 0.27 µm; P = 0.172). Furthermore, there were no significant interaction (P = 0.168) or condition effects between BFR (25.98 ± 4.17%) and normal (27.3 ± 6.49%) resistance exercise for sarcoplasmic area (P = 0.229). Exercise also increased sarcoplasmic area within the myofibril (pre-exercise, 24.42 ± 5.13%; postexercise, 28.95 ± 5.92%) for both conditions (P = 0.001). This case study demonstrates a unique BFR training-induced alteration in myofibril ultrastructure that appeared wave like and was accompanied by intracellular abnormalities that appeared to be fluid pockets of sarcoplasm disrupting the surrounding myofibrils.

Efficacy of L-Leucine Supplementation Coupled with a Calorie-Restricted Diet to Promote Weight Loss in Mid-Life Women.

OBJECTIVE: This study evaluated the effect of leucine supplementation coupled with a calorie-restricted diet over a 12-week period in mid-life overweight and obese women on body composition and resting metabolic rate (RMR). METHOD: This study was a randomized, single-blind, placebo-controlled trial in which 34 women were randomly assigned to either 10 g leucine (LEU) or placebo daily, while following a calorie-restricted diet A dual energy x-ray absorptiometry (DXA) analysis, metabolic rate assessment via a BodyGem® and anthropometrics were performed at baseline and after the 12-week study to determine changes in fat mass, lean mass and RMR. Main variables were analyzed using 2 (condition) by 2 (time) mixed design ANOVAs with repeated measures. Odds ratio was calculated by counting the number of individuals gaining or maintaining lean mass (p ≤ .05). RESULTS: Both groups lost a significant amount of weight due to both fat and lean mass loss, but there was no significant difference between groups, with RMR remaining unchanged over the course of the study and not significantly different between groups. The loss in lean mass was noticeably less, though not statistically significant (p = 0.644) for the women in the LEU group, with 38% vs. 6%, gaining or retaining lean mass during the intervention relative to the placebo. CONCLUSIONS: Our findings demonstrate that a greater proportion of mid-life overweight or obese women taking LEU supplements gained or maintained lean mass during intentional weight loss, though it did not reach a level of statistical significance.

Ubiquitin Proteasome System Activity is Suppressed by Curcumin following Exercise-Induced Muscle Damage in Human Skeletal Muscle.

PURPOSE: Curcumin is a polyphenolic compound that is suggested to dysregulate the ubiquitin-proteasome system (UPS). This study investigated the effects of curcumin supplementation on markers of UPS activity in response to muscle damage. METHODS: Twenty-three recreationally active male and females between the ages of 18-30 were randomized into a curcumin (CUR) or placebo (PLA) group. Both groups ingested 2 g of their respective supplement and 20 mg of piperine for 11 consecutive days. Following 8 consecutive days of supplementation, participants performed a 45-minute eccentrically-biased treadmill protocol at 60% VO2max. Muscle biopsies and delayed onset muscle soreness (DOMS) assessments were performed 30 minutes prior and 3, 24, 48, and 72 hours following exercise. Skeletal muscle ubiquitin, MAFbx/Atrogin-1, ubiquitin specific peptidase 19 (USP19), and chymotrypsin-like protease concentrations were measured using ELISA. A 3-way repeated measures ANOVA with pairwise comparisons was conducted with significance set at p ≤ 0.05. RESULTS: Compared to baseline, DOMS for both groups was significantly increased (p < 0.05) at all time points except 72 hours following exercise. No significant differences were found for USP19 between groups. Ubiquitin (p=.016) and MAFbx/Atrogin-1 (p=.006) were significantly lower for CUR compared to PLA. Additionally, MAFbx/Atrogin-1 was significantly greater for females (p=.013) compared to males. In males, curcumin resulted in significant reductions (p = .049) in chymotrypsin-like protease (p = .049). CONCLUSION: While elevations in UPS activity were not observed in response to muscle damage, curcumin supplementation in humans does appear to dysregulate basal UPS activity in the presence of exercise-induced muscle damage.

Effects of Hypohydration on Muscular Strength, Endurance, and Power in Women.

ABSTRACT: Gann, JJ, Andre, TL, Gallucci, AR, and Willoughby, DS. Effects of hypohydration on muscular strength, endurance, and power in women. J Strength Cond Res 35(2S): S102-S106, 2021-The purpose of this study was to determine the effects of dehydration on muscular strength, endurance, power, and perceptual measures in resistance-trained women. Ten resistance-trained women completed 2 bouts of exercise (1 repetition maximum [1RM] for bench press and angled leg press followed by 5 sets to failure of 75% of 1RM and vertical jump), either dehydrated (∼3% body mass) (DT) or heat-exposed with fluid replacement (HT). Paired t-tests revealed bench press 1RM was significantly lower for DT (42.7 ± 14.5 kg) compared with HT (44.1 ± 13.9 kg). No significant difference was found for leg press 1RM (DT = 216.1 ± 55.0 kg; HT = 223.4 ± 55.7 kg). There was also no difference in total reps completed for bench press (DT = 33.5 ± 5.0; HT = 33.0 ± 5.5) or leg press (DT = 42.6 ± 20.3; HT = 45.8 ± 19.7). There was no significant difference for vertical jump height (DT: 45.8 ± 5.2 cm, HT: 46.9 ± 6.0 cm). Ratings of perceived exertion (RPE) and session RPE were not significantly different between trials. Significant differences for perceived recovery status (DT: 5.1 ± 2.2, HT: 7.2 ± 1.1) and perceived readiness (DT: 4.2 ± 1.0, HT: 2.5 ± 0.5) indicate subjects expected impaired performance during DT. The current results suggest that previous night dehydration may have a negative impact on both bench press 1RM performance and perceptual feelings of recovery in resistance-trained women.

Neoprene Knee Sleeves of Varying Tightness Augment Barbell Squat One Repetition Maximum Performance Without Improving Other Indices of Muscular Strength, Power, or Endurance.

ABSTRACT: Machek, SB, Cardaci, TD, Wilburn, DT, Cholewinski, MC, Latt, SL, Harris, DR, and Willoughby, DS. Neoprene knee sleeves of varying tightness augment barbell squat one repetition maximum performance without improving other indices of muscular strength, power, or endurance. J Strength Cond Res 35(2S): S6-S15, 2021-Neoprene knee sleeves are commonly used by powerlifters and recreational users but are heavily under-researched. Furthermore, no data exist on whether knee sleeves of varying compressive tightness impact muscular performance similar to commonly used knee wraps, which are both generally effective and more so when increasingly constrictive. Fifteen resistance trained, knee sleeve naive, recreational weight lifting men (22.1 ± 4.1 years; 177.5 ± 5.9 cm; 87.8 ± 7.8 kg) visited the laboratory on 3 separate occasions one week apart, assigned in a randomized, crossover, and counterbalanced fashion to either a minimally supportive control sleeve (CS) condition, a manufacturer-recommended sizing neoprene knee sleeve ("normal" sleeve; NS), or a one size smaller (than NS) neoprene knee sleeve (tighter sleeve [TS]). On each visit, subjects sequentially completed vertical jump (countermovement and squat jumps for both peak and mean power), one repetition maximum (1RM) barbell squat, and GymAware assessments (peak power, peak velocity, and dip) at 90% (reported) and 100% (tested) 1RM as well as one-leg extension (1RM, repetitions to failure, and total volume load at 75% 1RM) tests. All data were analyzed using one-way repeated measures analysis of variance at p < 0.05. Analysis revealed a significant condition effect on barbell squat 1RM (p = 0.003; η2 = 0.339), whereby both NS (p = 0.044; 166 ± 24 kg) and TS (p = 0.019; 166 ± 21 kg) outperformed CS (161 ± 22 kg), with no difference between neoprene sleeves. Conversely, no other tested parameters differed between knee sleeve conditions (p ≥ 0.05). The present results demonstrate that neoprene knee sleeves may function independent of tightness, relative to recommended sizing and ultimately unlike knee wraps. Furthermore, the singular benefits observed on barbell squat maximal strength potentially suggests an exercise-specific benefit yet to be fully elucidated.

Efficacy of L-leucine Supplementation Coupled With Resistance Training in Untrained Midlife Women.

Objective: This study investigated the effects of leucine supplementation with resistance training (RT) in untrained peri- and postmenopausal women on fat free mass, strength, and select anabolic-related hormones.Method: This was a randomized, double-blind, placebo-controlled trial, in which 36 untrained women were randomly assigned to either a leucine or placebo supplement group coupled with 10 weeks of RT, performed thrice weekly, while ingesting either 5 g of placebo or leucine. Before and after RT, body composition and muscle strength were assessed and venous blood samples obtained to determine the levels of estradiol, testosterone, insulin-like growth factor-1, growth hormone, and cortisol. Data were analyzed by utilizing separate 2 × 2 [group × time (pretest and posttest)] factorial analyses of variance with repeated measures (p ≤ .05).Results: There were no significant changes or differences between groups in fat free mass or with any of the serum hormones assessed in response to supplementation. However, there were significant increases in strength in both groups in response to RT, but not supplementation.Conclusions: Peri- and postmenopausal women had significant increases in strength following 10 weeks of RT, with no additional effects from supplementing with leucine. There were no significant changes in either group regarding fat free mass or serum hormones.

Effects of Pyrroloquinoline Quinone (PQQ) Supplementation on Aerobic Exercise Performance and Indices of Mitochondrial Biogenesis in Untrained Men.

Objective: Pyrroloquinoline quinone (PQQ) is a novel supplement involved in processes such as mitochondrial biogenesis and cellular energy metabolism. Since endurance exercise and PQQ exhibit similar mechanisms for mitochondrial biogenesis, it is plausible that PQQ may have ergogenic value. Therefore, the purpose of this study was to examine the effects of a six-week endurance exercise training program on mitochondrial biogenesis and aerobic performance in non-endurance-trained males.Methods: Twenty-three males were randomized to consume 20 mg/day of PQQ or placebo (PLC). Both groups followed a supervised six-week endurance exercise training program. Body composition was assessed by dual-energy-x-ray-absorptiometry (DEXA). Aerobic exercise performance and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a biochemical marker for mitochondrial biogenesis, were assessed before and after the six-week endurance training/supplementation program.Results: There were no significant differences between groups in aerobic performance after endurance-training (p > 0.05). However, there were significant improvements in peak oxygen consumption (VO2peak) and total exercise test duration after endurance-training, irrespective of group (p < 0.05). The PQQ group had a significant increase in PGC-1α protein levels from baseline to post endurance training compared to PLC (p < 0.05). Furthermore, the PQQ group had higher PGC-1α protein levels after 6 weeks of endurance training compared to PLC (p < 0.05).Conclusions: Supplementation of PQQ does not appear to elicit any ergogenic effects regarding aerobic performance or body composition but appears to impact mitochondrial biogenesis by way of significant elevations in PGC-1α protein content.

Decreased Serum Levels of C-Terminal Agrin in Postmenopausal Women Following Resistance Training.

Elevated circulating C-terminal agrin fragment (CAF) is a marker of neuromuscular junction degradation and sarcopenia. This study sought to determine if resistance training (RT) impacted the serum levels of CAF in perimenopausal (PERI-M) and postmenopausal (POST-M) women. A total of 35 women, either PERI-M or POST-M, participated in 10 weeks of RT. Body composition, muscle strength, and serum estradiol and CAF were determined before and after the RT. The data were analyzed with two-way analysis of variance (p ≤ .05). Upper body and lower body strength was significantly increased, by 81% and 73% and 86% and 79% for the PERI-M and POST-M participants, respectively; however, there were no significant changes in body composition. Estradiol was significantly less for the POST-M participants at pretraining compared with the PERI-M participants. CAF moderately increased by 22% for the PERI-M participants in response to RT, whereas it significantly decreased by 49% for the POST-M participants. Ten weeks of RT reduced the circulating CAF in the POST-M women and might play a role in attenuating degenerative neuromuscular junction changes.

Myosin Heavy Chain Composition, Creatine Analogues, and the Relationship of Muscle Creatine Content and Fast-Twitch Proportion to Wilks Coefficient in Powerlifters.

Machek, SB, Hwang, PS, Cardaci, TD, Wilburn, DT, Bagley, JR, Blake, DT, Galpin, AJ, and Willoughby, DS. Myosin heavy chain composition, creatine analogues, and the relationship of muscle creatine content and fast-twitch proportion to Wilks coefficient in powerlifters. J Strength Cond Res 34(11): 3022-3030, 2020-Little data exist on powerlifting-specific skeletal muscle adaptations, and none elucidate sex differences in powerlifters. Powerlifters tend to display higher fast-twitch fiber content and phosphagen system dependence. Nevertheless, it is unknown whether fast-twitch fiber or muscle creatine content are predictive of competitive powerlifting performance (via Wilks coefficient). Twelve actively competing powerlifters (PL; n = 6M/6F; age = 21.3 ± 1.0; 3.0 ± 1.8 year competing; 7.3 ± 6.6 meets attended) and 10 sedentary controls (CON; n = 5M/5F; age = 19.4 ± 2.0 year) underwent vastus lateralis muscle biopsies and venipuncture to compare the myosin heavy chain (MHC) fiber type and creatine analogue profiles between groups of both sexes, and determine whether MHC IIa and muscle total creatine (MTC) composition predict powerlifting performance. Samples were analyzed for specific MHC isoform (I, IIa, and IIx) content via mixed homogenate SDS-PAGE, and creatine analogues (MTC, muscle creatine transporter [SLC6A8], serum total creatine [STC], and serum creatinine [CRT]). Furthermore, MHC IIa and MTC content were compared with Wilks coefficient using Pearson correlation coefficients. Male PL MHC content was 50 ± 6% I, 45 ± 6% IIa, and 5 ± 11% IIx, versus 46 ± 6% I, 53 ± 6 IIa, and 0% IIx in female PL. Conversely, male CON MHC content was 33 ± 5% I, 38 ± 7% IIa, and 30 ± 8% IIx, vs. 35 ± 9% I, 44 ± 8% IIa, and 21 ± 17% IIx in female CON. Muscle total creatine, SLC6A8, STC, and CRT did not significantly differ between groups nor sexes. Finally, neither MHC IIa content (r = -0.288; p = 0.364) nor MTC (r = 0.488; p = 0.108) significantly predicted Wilks coefficient, suggesting these characteristics alone do not determine powerlifting skill variation.

Acute Maltodextrin Supplementation During Resistance Exercise.

Most of the research investigating the ergogenic enhancing mechanisms of carbohydrate have been conducted using aerobic based exercise. Therefore, the purpose of this study was to investigate the effects of pre-exercise maltodextrin ingestion on resistance exercise performance, serum insulin, epinephrine, glucose, and muscle glycogen concentrations. In a double blind, cross over, repeated measures design, participants completed four sets to failure at 70% of 1-RM with 45s rest on the angled leg press with or without pre-exercise maltodextrin (2g/kg) after a 3hr fast. Serum glucose, epinephrine, and insulin were assessed at baseline, 30 min post-ingestion, immediately after, and 1hr post-exercise with or without carbohydrate supplementation. Muscle glycogen was assessed from biopsy specimens sampled from the vastus lateralis before supplementation, immediately after exercise, and 1hr post exercise under both conditions. There was no main effect of supplement on resistance exercise performance (p = 0.18). Muscle glycogen concentration decreased across time for both groups (p < 0.001). There was an interaction in serum glucose decreasing more during exercise in the carbohydrate condition (p = 0.026). An interaction occurred showing insulin decreased during exercise in the carbohydrate condition (p = 0.003). Also, there was a main effect of insulin being elevated with carbohydrate consumption (p = 0.027). Epinephrine was decreased across all time points after carbohydrate ingestion (p = 0.023). Carbohydrate supplementation before resistance exercise did not improve leg press performance to fatigue despite increased metabolic substrate availability. These results indicate that pre-exercise dietary carbohydrate will be utilized preferentially during exercise due to decreased epinephrine, decreased serum glucose, and increased insulin concentrations. However, the increases in glycolytic substrate availability will not increase exercise performance or glycogen content following 1hr of recovery.

Mechanisms Behind Blood Flow-Restricted Training and its Effect Toward Muscle Growth.

Hwang, P and Willoughby, DS. Mechanisms behind blood flow-restricted training and its effect toward muscle growth. J Strength Cond Res 33(7S): S167-S179, 2019-It is widely established throughout the literature that skeletal muscle can induce hypertrophic adaptations after progressive overload of moderate-to-high-intensity resistance training. However, there has recently been a growing body of research that shows that the combination of blood flow-restricted (BFR) training with low-intensity resistance exercise can induce similar gains in muscular strength and hypertrophic adaptations. The implementation of external pressure cuffs over the most proximal position of the limb extremities with the occlusion of venous outflow of blood distal to the occlusion site defines the BFR training protocol. There are various mechanisms through which BFR training may cause the stimulations for skeletal muscle hypertrophy and increases in strength. These may include increases in hormonal concentrations, increases within the components of the intracellular signaling pathways for muscle protein synthesis such as the mTOR pathway, increases within biomarkers denoting satellite cell activity and apparent patterns in fiber type recruitment. There have also been scientific findings demonstrating hypertrophic effects within both BFR limbs and non-BFR muscles during BFR training programs. The purpose behind this critical review will be to provide a comprehensive discussion on relevant literature that can help elucidate the potential underlying mechanisms leading to hypertrophic adaptations after BFR training programs. This review will also explicate the various findings within the literature that focalizes on both BFR limb and non-BFR muscle hypertrophy after bouts of BFR training. Furthermore, this critical review will also address the various needs for future research in the many components underlying the novel modality of BFR training.

The Effect of 2 Weeks of Inactivated Probiotic Bacillus coagulans on Endocrine, Inflammatory, and Performance Responses During Self-Defense Training in Soldiers.

Hoffman, JR, Hoffman, MW, Zelicha, H, Gepner, Y, Willoughby, DS, Feinstein, U, and Ostfeld, I. The Effect of 2-Weeks of Inactivated Probiotic Bacillus coagulans on Endocrine, Inflammatory and Performance Responses During Self-Defense Training in Soldiers. J Strength Cond Res 33(9): 2330-2337, 2019-The effect of 2 weeks of inactivated Bacillus coagulans (iBC) ingestion on performance and inflammatory cytokines was examined during a self-defense course in soldiers. Sixteen male soldiers were randomly assigned to either iBC (n = 8) or placebo (PL; n = 8) in this double-blind study. Participants were garrisoned on base and participated in the same training tasks. Assessments were conducted in a single day before (PRE) and after the supplementation period (POST). During each testing session, participants were assessed for vertical jump power (VJP), muscle endurance, simulated casualty drag, and 2 100-m shuttle runs. Resting blood measures for testosterone, cortisol, creatine kinase, and inflammatory cytokines were also assessed. Mann-Whitney analysis of change (Δ) scores indicated no significant change (p's > 0.05) in any of the performance or blood variables. However, a trend (p = 0.089) was noted in the Δ score for VJP in iBC compared with PL. In addition, trends were observed in the change in IL-10 (p = 0.057) and IFNγ (p = 0.057). Magnitude based inferential analysis indicated that changes in VJP and simulated casualty drag were likely beneficial (90.7 and 80.4% likelihood effect, respectively) for iBC. In addition, iBC supplementation very likely augmented IL-10 concentrations, but was possibly negative for changes in IL-6, and likely negative for changes in TNFα and IFNγ. Changes in all other performance and blood markers were unclear. Results indicated that 2 weeks of iBC supplementation appeared to be beneficial for maintaining power and short-term speed performance, while attenuating the inflammatory response during intense training in a military self-defense course.

Mechanisms Behind Pyrroloquinoline Quinone Supplementation on Skeletal Muscle Mitochondrial Biogenesis: Possible Synergistic Effects with Exercise.

KEY TEACHING POINTS: • Endurance exercise training enables skeletal muscle adaptations that can induce increases in mitochondrial biogenesis, improve oxidative capacity, mitochondrial density, and mitochondrial function.• Pyrroloquinoline quinone (PQQ) has been identified as a novel supplement that is involved in physiological processes including redox modulation, cellular energy metabolism, mitochondrial biogenesis, and antioxidant potential.• There is emerging evidence to support that PQQ supplementation can upregulate the molecular signaling responses indicative of mitochondrial biogenesis within skeletal muscle.• If both endurance exercise and PQQ supplementation can elicit increases in the molecular responses indicative of mitochondrial biogenesis, it is possible that both PQQ and exercise may instigate a synergistic ergogenic response.• There is a scarcity of research exploring the possible role of PQQ supplementation with concomitant endurance exercise. Therefore, future research is necessary to investigate the ergogenic potential behind PQQ supplementation in conjunction with endurance exercise.

A Comparison of the Nutrient Intakes of Macronutrient-Based Dieting and Strict Dieting Bodybuilders.

The purpose of this study was to provide a descriptive assessment of the nutritional habits of competitive bodybuilders and compare the nutrient intakes of macronutrient-based dieting and strict dieting individuals. Data from 41 subjects (30 males and 11 females) were used in analyses. Participants completed a comprehensive food frequency questionnaire, and diets were analyzed using a computer system. Males consumed an average of 2,577.2 kcal (SD = 955.1), with an average fat intake of 83.6 g (SD = 41.3), an average carbohydrate intake of 323.3 g (SD = 105.2), and an average protein intake of 163.4 g (SD = 70.4). There were no significant differences between male macronutrient-based dieting and strict dieting bodybuilders when mean intakes were compared for all nutrients, including the macronutrients, selected vitamins and minerals, dietary fiber, added sugars, and saturated fat. Females in this study consumed an average of 1,794 kcal (SD = 453.1), with an average fat intake of 58.3 g (SD = 23.1), a mean carbohydrate intake of 217.8 g (SD = 85.9), and an average protein intake of 103.8 g (SD = 35.7). For females, macronutrient-based dieters consumed significantly greater amounts of several nutrients, including protein, vitamin E, vitamin K, and vitamin C. Over half of individuals from all groups consumed less than the recommended amounts of several of the micronutrients. Based on this information, it is recommended that competitive bodybuilders should be advised to take their micronutrition into greater consideration.

Partial Compared with Full Range of Motion Resistance Training for Muscle Hypertrophy: A Brief Review and an Identification of Potential Mechanisms.

Newmire, DE and Willoughby, DS. Partial compared to full range of motion resistance training for muscle hypertrophy: A brief review and an identification of potential mechanisms. J Strength Cond Res 32(9): 2661-2673, 2018-Resistance training promotes skeletal muscle hypertrophy; there are specific recommendations of intensity, volume, and duration that appear to facilitate hypertrophy the greatest. However, currently, there is not a definitive consensus on optimal range of motion. It appears that the partial range of motion (pROM) mode of exercise may have some similar benefit on muscle hypertrophy as the conventional full range of motion (fROM). Because of the dynamic and multiplanar movement pattern of a multijoint resistance exercise, there may be variation in human force-length and strength-curve theories, which may influence optimal muscle force production at differing portions of a fROM. This suggests specific muscle groups may potentially be optimally recruited during a specific portion of the exercise. The majority of previous research has primarily focused on strength outcomes opposed to muscle hypertrophy. The purpose of this brief review is to highlight the limited and relative pROM literature on muscle hypertrophy and some potential pROM mechanisms that require investigation to assess any plausible relationships. Some potential mechanisms and outcomes of interest are muscle time under tension, muscle activation, and nonuniform hypertrophy. This mode of resistance exercise requires further evaluation on hypertrophic responses; if proven efficacious, it may be employed to those in rehabilitative environments and those that seek more specific regional, local hypertrophic responses such as physique competitors.

Effectiveness of Fish Oil Supplementation in Attenuating Exercise-Induced Muscle Damage in Women During Midfollicular and Midluteal Menstrual Phases.

McKinley-Barnard, SK, Andre, TL, Gann, JJ, Hwang, PS, and Willoughby, DS. Effectiveness of fish oil supplementation in attenuating exercise-induced muscle damage in females during midfollicular and midluteal menstrual phases. J Strength Cond Res 32(6): 1601-1612, 2018-The purpose of this study was to determine whether the differences in estrogen levels during the female menstrual cycle and fish oil supplementation would attenuate eccentric exercise-induced muscle damage and delayed-onset muscle soreness (DOMS). In a double-blind fashion, 22 physically active females (20.9 ± 1.4 years, 63.5 ± 9.0 kg, 165.2 ± 7.5 cm) were randomly assigned to ingest either 6 g of fish oil (n = 11) or placebo (n = 11) daily for 21 days. Participants underwent an eccentric exercise bout of the knee extensors on 2 occasions during the midfollicular (MF) and midluteal (ML) phases of the 28-day menstrual cycle. Before (PRE), at 6 (6HRPOST), and at 24 hours postexercise (24HRPOST) for each session, participants underwent assessments of DOMS, muscle strength, and had venous blood samples and muscle biopsies obtained. Data were analyzed using a 2 × 2 × 3 repeated-measures multivariate analysis of variance for each criterion variable (p ≤ 0.05). Further analysis of the main effects for the test was performed using separate 1-way analyses of variance. Delayed-onset muscle soreness was significantly greater at the 6HRPOST and 24HRPOST timepoints compared with PRE (p < 0.001). Superoxide dismutase and tumor necrosis factor-alpha (TNF-α) concentrations were significantly higher at the MF phase compared with the ML phase (p < 0.001 and p = 0.05, respectively). There were no statistically significant differences observed for muscle strength, myoglobin, NF-Kß p50, or NF-Kß p65. This study demonstrates that higher levels of estrogen may exert a cytoprotective effect on the sarcolemma.

Restrictive Breathing Mask Reduces Repetitions to Failure During a Session of Lower-Body Resistance Exercise.

Andre, TL, Gann, JJ, Hwang, PS, Ziperman, E, Magnussen, MJ, and Willoughby, DS. Restrictive breathing mask reduces repetitions to failure during a session of lower-body resistance exercise. J Strength Cond Res 32(8): 2103-2108, 2018-The purpose of this study was to determine the effect of restrictive breathing mask (RBM) on muscle performance, hemodynamic, and perceived stress variables during a session of lower-body resistance exercise. In a crossover design, 10 participants performed 2 separate testing sessions, RBM and no mask, consisting of squat, leg press, and leg extension. The paired-samples t-test was used for session rating of perceived exertion (S-RPE), perceived stress before and after, heart rate (HR), pulse oximetry, and a 2 × 4 (session [mask, no mask] × time [squat exercise, leg press exercise, leg extension exercise, total resistance exercise session]) factorial analysis of variance with repeated measures (p ≤ 0.05). A significant decrease was found in total repetitions during the RBM condition (p < 0.01). A majority of the decrease in repetitions to failure occurred in the squat (p < 0.05) and in the leg press (p < 0.01), whereas no difference was observed in leg extension (p = 0.214). A significant increase was observed in S-RPE during the RBM session (p < 0.01). A significant increase was found in prestress (p < 0.01) and poststress (p = 0.01) in the RBM session. No significant difference existed for HR between exercise sessions (p = 0.08). A significant decrease existed in pulse oximetry during the RBM session (p < 0.01). The use of an RBM had a negative effect on the number of repetitions completed during an acute session of lower-body resistance training.